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design and construction of a robot for polar

1. Figure 7 23 SAR Greenland SAR movement using a 100x1 meter with waypoints in a line 155 Ideal SAR Movement MARVIN despite the ability to correctly navigate the waypoints could not move on parallel or straight lines well enough to get ideal SAR data So to get the data a human operator was used during which control data would be recorded for future use The human operator could also cheat in the driving by utilizing the fact that the rover is 2m wide so driving over the track would produce the correct spacing The ideal driving pattern can be seen in Figure carnal Figure 7 24 SAR movement with a human driving 156 7 4 2 3 Overall Accuracy Overall MARVIN achieved waypoint accuracy to 2 83m with 1 54 meter standard deviation and was off of the line and average of 13 78 meters with a standard deviation of 19 56 7 4 2 4 2004 Assessment MARVIN did quite well on the ice however it got stuck in snow a few times The weather proofing kept the cold and exhaust out while letting airflow into the vehicle Waypoint navigation worked reasonably well but will need to be enhanced to provide improved SAR movement 157 Waypoint Analysis Kansas File topeon_2004_4 25 4 28 26 log topcon_2004_4 26 0 55 16 log topcon_2004_4 26 1 topcon_2004 4 26 topcon_2004 4 26 topcon_2004_4 26 topcon_2004_4 26 9 46 28 log topcon_2004_4 26 8 59 _33 log topcon_2004 4 29 3 12 26 log topcon_2
2. 95 6 2 Motor mount design front view 96 6 3 Replacement seat design 97 6 4 Installed actuators 98 6 5 Power required to control MARVIN Samples every millimeter of A IS ee 99 63M covered in ice after being dropped on the mow 100 6 7 Topcon GPS rack mount box lt 444 e 22 eV eee dK SH 101 6 8 Dimension drawing of the MotionPak IL 102 6 9 TCM multi sensor ex oir a A A 103 6 10 SICK LMS221 outdoor laser range finder 104 dra dora de 106 a a a OG 107 Cees a a Gk 108 6 14 Frame side view measurements in inches 109 FAA 110 erre 111 A A ee Re ee eG 112 6 18 Frame rack back measurements in inches 112 re ee RA 113 620 MARVIN Tully assembled for the Greenland 2001 feld season 114 6 21 Information display window for a human to track vehicles and oe a e ea 119 xiii 7 1 Bob doing waypoint navigation in the lab 121 7 2 Waypoint navigation in Kansas first test run error threshold was set at 9 meters 2 a aa 133 7 3 Waypoint navigation in Kansas driving out about 80 meters nee Ree eee Sane oro an 134 7 4 Waypoint navigation in Kansas 180 degree turn then driving across AP 135 7 5 Waypoint navigation in Kansas moving to the 20 yard line 136 7 6 Waypoint navigation in Kansas moving to a base location 137 7 7 Waypoint navi
3. motor is defined as an actuator that physically moves A switch changes the world by setting values There may be more types of actuators but these two where what was necessary at the time Actuator hierarchy is shown in Figure gt Actuator es amp 4 Switch Sony EYI 30 Sony EYI 30 Pelco Pelco Pelco Sony EVI 30 Tilt Motor Pan Motor Pan Motor Tilt Motor Zoom Control Zoom Control Figure 5 8 Actuator class hierarchy 68 5 2 4 1 Motor A motor causes an object to move in the real world Motors move legs cause wheels to spin and move in a line Motors are categorized into three basic types each with its own movement style 1 Wheel motors rotate at a given rate in rotations per minute allowing continuous movement As an example a Nomadic Scout has two wheel motors a left and right motor which are used in a differential drive system Each wheel can be turned at different rates causing the robot to move about A wheel motor does not have to be attached to a wheel it can be used to open a valve at a certain rate move a worm gear or anything that involves a rate of rotation 27 2 Servo motors are used to move to a specific angle As such the servo motor class takes an angle to move to as its value Servo motors are used in walking legs pan tilt cameras and many other places where a motor needs to go to a specific angle Some servos can be used as wheels the distinction being that a servo moves to speci
4. 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Belkin Components USB Video Video Bus II 2000 Online Available http web belkin com support download de E 391 K Betk The nmea 0183 protocol 2000 Online Available ttp nmeatool nmea2000 de download 0183 pdf Danaher Motion Actuator catalog 2004 Online Available http www danaherlinear com PDFs Catalogs_and_Brochures Actuator_Catalog pdf Gorilla Vehicles Gorilla electic vehicles specifications 2003 Online Available http www gorilla com GorillaSpecifications htm R W Gunderson M W Torrie N S Flann C M U Neale and D J Baker The collective Gis and the computer controlled farm Geospacial Solutions pp 2 6 Jul 2000 D PINROB A Portable API for Industrial Robots International Conference on Reliable Software Technologies Jun 1998 Itronix Gobook max 2004 Online Available http www itronix com products notebooks gobookmax asp KU PRISM Team Prism home Polar radar for ice sheet measurements Lawrence Kansas 2004 Online Available http www ku prism org Linmot Inc Linmot 3d image 2004 Online Available http www linmot com images p01 23x80_3d jpg Linmot data book 2003 2004 2004 Online Available http www linmot com datasheets LinMotDataBook2003 2004 pdf Mattracks Inc L
5. 325 8519094 0 113652 0 074424 0 037015 0 123104 0 229059 0 125465 0 095802 0 498348 0 097242 0 064945 0 158667 0 059333 0 108294 0 129551 0 136422 0 0745 0 2165 0 1025 0 11 0 087 0 132091 0 098367 0 096129 0 259094 0 1556 0 6216 0 718687 0 516372 1 918367 0 1138 0 564 0 13 0 056146 0 017924 0 0666 0 0576 0 033416 0 099301 27 98092 0 300833 0 0674 0 311818 0 097 0 3725 0 0556 0 378182 0 0832 0 346667 0 503 1 060909 0 1174 0 265 0 2236 1 030909 0 0404 0 286 3 746032 0 432328 0 170465 0 086909 1 73183 0 076383 0 261623 0 18324 0 275689 0 11648 2 233364 0 186748 4 404344 0 133721 1 216044 0 217221 0 913952 0 064755 0 175023 0 082197 0 160401 0 082197 0 483136 0 244286 0 069401 0 960911 3 671118 8 Conclusion 8 1 Summary Overall everything worked as expected Waypoint navigation was successful in multiple environments and on multiple platforms MARVIN performed well in Kansas and in two field experiments The overall accuracy of waypoint navigation depended mostly on the kinematics of the system how the mechanics of Marvin acted in the different environments The software system on Bob provided an excellent way to test code with minimal risk before releasing to the code to MARVIN 8 2 Contributions The major contribution of this thesis is the cross platform automation code which can now be used on future autonomous rovers The field data will also help improve t
6. 1 5 132 meters with a range of 0 21 to 7 24 not much different from Kansas However the ability to stay near the line decreased to 16 78 meters from the line with a standard deviation of 21 69 and a range of 1 87 to 146 62 The largest deviation from the line being when the vehicle was navigating a two kilometer path Figure 7 2 Waypoint navigation in Kansas first test run error threshold was set at 5 meters 133 Figure 7 3 Waypoint navigation in Kansas driving out about 80 meters returning and driving back 134 3 q__ a oo A ooo o e Zoomin Zoom Out Figure 7 4 Y 4313897 227047793 DA S os Phe y Tes TA y GF A an y A K lt lt aJe Leli u JETA Waypoint navigation in Kansas driving across assvault and grass terrain 135 180 degree turn then Figure 7 5 Waypoint navigation in Kansas moving to the 20 yard line 136 Figure 7 6 Waypoint navigation in Kansas moving to a base location 137 Figure 7 7 Waypoint navigation in Kansas moving to location 138 a known Figure 7 8 Waypoint navigation in Kansas full 180 degree turn test then followed by a driving to a base location 139 Figure 7 9 Waypoint navigation in Kansa
7. 4 Height cm 117 99 122 Length cm 201 178 244 Width cm 111 88 118 Power HP 5 5 Top Speed km h 40 3 Turning Radius cm 518 16 Control Type Handle Bar Handle Bar Handle Bar Weather Proof Electric N Y N Table 2 3 Information on ATVs 30 Amphibious Name Max IV Buffalo BigFoot Manufacturer R I R I Argo Cost 8 030 00 12 030 00 8 000 00 Wieght kg 351 408 414 Towing kg 454 454 654 Max Load kg 363 408 327 Tires 6 6 6 Height cm 107 132 Length cm 244 251 Width cm 147 147 Power HP 16 20 18 Top Speed km h 32 3 32 3 39 0 Turning Radius cm In Place In Place In Place Control Type Two Sticks Two Sticks Two Sticks Weather Proof Y Y Y Electric N N N Table 2 4 Information on amphibious ATVs 31 Tanks Robots Name AAVP7A 1 4 Nomad Dante Manufacturer Interdacom CMU CMU Cost 10 000 00 1 600 000 00 Expensive Wieght kg 208 Towing kg Max Load kg Tires Track 4 8 Legs Height cm 76 Length cm 198 240 Width cm 82 240 Power HP Top Speed km h Turning Radius cm In Place In Place In Place Control Type Radio Remote Auto Remote Auto Weather Proof Y Y Electric Y Y Table 2 5 Information on tanks and robots 32 Figure 2 21 The original Buffalo prior to modifications The MaxATV Buffalo an amphibious ATV was sele
8. A CHF Paneam Vast Antenna High Gain Assembly PMA Antenna HGA Capture Filter Magnets LA AS Arrays Hazcam pair Warm Instrument Electronics Deployment Box WEB Rocker Bogie Device IDD Mobility System Z ta Site Instruments APXS MB MI RAT Figure 2 20 NASA s Spirit rover 27 2 3 Base Selection Final choice of the mobile base platform was made after looking at all of the details of the vehicles reading user reviews viewing records of each vehicle in use and finally examining and test driving vehicles Tables 2 2 to show a description of all of the mobile base vehicle types considered for automation as part of this thesis 28 Snowmobiles Name VK 540 Ill Pantera 800 EFI Manufacturer Yamaha Arctic Cat Cost 7 699 00 7 999 00 Wieght kg 292 211 Towing kg Max Load kg Tires Track Ski Track Ski Height cm 135 Length cm 312 338 Width cm 135 122 Power HP 140 Top Speed km h Turning Radius cm Control Type Handle Bar Handle Bar Weather Proof Y Y Electric N N Table 2 2 Information on snowmobiles 29 ATV Name Big Bear 4x4 Gorilla 500 4x4 TBX Manufacturer Yamaha Gorilla Vehicles Arctic Cat Cost 5 199 00 5 500 00 6 100 00 Wieght kg 253 250 335 Towing kg 411 1800 ATT Max Load kg 120 270 181 Tires 4 4
9. F gt J ep encoder CA X Pu rear brake cro S ah 3 pinion gear mi yi throttle Y EE potentiometer shaft wheel hub gt r gear attached gearshitt shalt i to wheel rim Figure 2 11 Gryphon I internals 2 2 3 Amphibious ATVs Amphibious ATVs design allows them to not only go over dirt and climb steep hills but also float Floating while not a requirement provides a waterproof and thus snow proof bottom Protecting the gears engine and other equipment from snow and ice is required Most of the amphibious ATVs drive by a method 17 Figure 2 12 Gryphon III with field arm of skid steering Skid steering involves two brakes and a throttle and allows for a tight turning radius not quite in place but very close to it 2 2 3 1 Vehicles Recreatives Industries makes a line of amphibious ATVs that use six wheels and drive using skid steering The MaxATV line comes in three different versions a small two seater a four person model and finally a truck like model Any of these models can be fitted with tracks to help them travel across the snow Recreational Vehicles also makes a weatherproofing kit 33 Figure 2 13 Recreatives Industriess MaxATV Argo provides a range of amphibious vehicles that use from six to eight wheels All these vehicles use a skid steering drive Argo provides a track kit for 19 their vehicles However they do not provide directly weather proofing k
10. Java to have nanosecond resolution I Java also provides extensions for remote access and control known as remote method invocation or RMI RMI will allow remote operation of the rover as well as the ability to view the sensor data from afar Of course there will be times where Java alone is not enough In these instances C functions can be called from Java using the Java Native Interface JNI Java can also utilize higher level logic languages KAWA is a scheme interpreter for Java and JESS is a ruled based system similar to CLIPS There are also various Prolog implementations in Java All of these features are in addition to the robust and object orientated nature of Java 5 2 Design The best design would have the software mimic the function of the hardware using a hardware abstraction layer to allow for the independence of the code With hardware abstraction portability and simulation become attainable goals However this still requires writing wrapper code or device drivers for any used equipment The overall design is that robots are composed of devices that contain sensors actuators various parameters and a way of communicating to them The sensors and actuators are then combined to form system Systems combine with other sensors and systems to form more complex behaviors This API design is shown in Figure 5 2 1 Device Every piece of equipment can be seen as a Device A Device is an upper level class that represents a r
11. Ost en 3 in i el HH Is lt lt lt 1 Il 0 1 gt gt gt gt Figure 7 13 Waypoint navigation in Greenland MARVIN moves to the bottom point then to the top and back to the bottom x E 517571 24932666734 y 8053920 973262481 Zoom In zl 3 5 Zoi om Out nr ot E nr me nr mr nj jaana ii ZI tt LE it Tt Is lt lt lt 1 a Il ii 1 gt gt gt gt Figure 7 14 Waypoint navigation in Greenland MARVIN performing a full 180 to get the target 145 y JE E Lp 517568 7423311318 8053920 343504357 Zoom In 18 0531939 22 NW N NE ensalora22 12 059190922 w E 805388922 emosalazaz2 ensalasa22 sw sS SE ensalasaz2 E g of a a N fo Toog oom Ou ES A A Is lt lt lt 1 gt a Il it 1 gt gt gt gt Figure 7 15 Waypoint navigation in Greenland MARVIN performing a full 180 to get the target 146 S Jee x ve 517676 30498905637 ne Lou fi F
12. SAR will be used to gather as detailed information about the bottom of the ice sheet and determine if ice is frozen to the bedrock or if there is water at the bedrock A bistatic SAR utilizes two set of radar equipment one to send and the other to receive During the process one antenna aims at a fixed location while the other moves around The second antenna system moves in a pattern to collect a wide area of signals about target thus creating many data points for a single target acting like increasing the antenna size This allows for an antenna as big as needed The tradeoff is that it takes longer to achieve detailed data about a single point Polar regions like Antarctica and Greenland are quite cold with tempera tures below zero during the summer Measuring the ice especially using a SAR is tedious process Difficulties with such situations it becomes apparent that having a robot that will not care about the weather and is willing to work so long as it is fueled becomes quite useful This was the motivation for constructing a robot that can survive the cold and snow Henceforth the robot shall be known as MARVIN or Mobile Arctic Robotic Vehicle with Intelligent Navigation 1 3 Approach Design and construction of the UGV is divided into four phases platform assessment actuation winterization and testing local and polar Possible base platforms range from RC cars to custom built robots In the first phase a number of factors
13. The navigator controls the Movement2D and uses the heading and position sensors from either robot The navigator moves by turning at a minimum speed until the desired heading is found and then moves forward in the proper direction 6 5 5 Obstacle Avoidance The navigator can optionally have obstacle avoidance passed to it Obstacle avoidance uses the distance sensor sonar for Bob laser range finder for MARVIN to navigate safely Obstacle avoidance works by modifying the desired heading to a safe heading that is devoid of obstacles When the obstacle is passed or there are no obstacles the avoider just lets the desired heading be the correct heading 6 5 6 Mobile Radar Mobile Radar uses the navigator to provide a way of testing the SAR movements indoors The mobile radar interface takes input from either the local GUI a remote GUI or eventually an intelligent system that analyzes the data from the SAR The interface requires that the points be in the same format as the position sensor So for Bob the distance from start is used and MARVIN uses the GPS UTM coordinates 116 6 5 7 Remote Control All of the sensors Movement2D and Mobile Radar are exposed to RMI The GUIs are tested as is the joystick control which now uses the remote movement2D instead of normal movement2D Remote control shows that the network response is a little slow from the joystick to either vehicle for the actual control 6 6 SAR Tracked Vehicle Sin
14. a two dimensional plane Control of movement on the 2D plane is done by declaring forward and right target velocities The vehicle should make a safe effort to achieve these goals All motion can be extrapolated from trying to move forward backward by a minus or right left by minus By combining forward motion and side motion the vehicle should turn By using forward motion the vehicle moves forward Strafing uses side motion though just side motion for most vehicles types is turning Not all vehicles can achieve perfect movements but they should be able to come close to the request on a two dimensional plane The Movement2D is borrowed from JAUS movement controls but is simplified to only controlling two dimensions and removes the braking controls Breaking should be an attempt to get to proper velocity or since the actuator can be accessed directly a safety control system could control the brakes By using this high level of control many types of vehicles can be controlled as seen in the Joystick Control and Navigator classes How the Movement2D classes fit together can be seen in Figure 5 12 Differential Drive A differential drive system drives two wheels independently in different directions This class controls two similar wheel motors in an attempt to move at proper velocities The wheel motors are driven in the same direction for forward and reverse the side velocity adds to left motor and subtracts motion from the right motor
15. and strong and can be molded into the exact form needed It is still a plastic so it becomes brittle at extremely cold temperatures The design of the mold must incorporate any future additions such as doors and holes for wires Without knowing exactly what equipment will be installed for automation SAR or other test applications this is problematic A model mock up shell is shown in Figure 47 4 1 3 Metal A metal shell welded to the base vehicle will make a strong structure Metal can be drilled into and extra pieces can be welded on later if necessary However the weight and density of iron will cause the vehicle to be too heavy and welding lighter metals such as aluminum and titanium require extensive expertise and could be very costly 4 1 4 T slotted Extrusions T slotted extrusions made of aluminum provide a lightweight modular solution that allows components to be added later The extrusions are connected by bolts which can rattle loose over time In addition a frame will need to be reinforced with cross beams to minimize flex T slotted extrusions only create a frame holes in the frame will need to be filled in with other materials 4 2 Sealing No matter what type of shell is used there will always be gaps in the structure Gaps come from drilling through the shell for doors vents and wires These holes need to be filled in to insure that no blowing snow gets into the vehicle However not all of the holes nee
16. any class that needs raw data using an http request video audio documents etc What this provides in the end is a way to grab the images and display them to the screen or analyze the data By decomposing both cameras down Pan Servo Motor Tilt Servo Motor Zoom Linear Switch and Image a more generalized class the PanTiltZoomCon troller can control both cameras This is done without worrying about what features or parameters need to be sent to both It only knows about and only concerns itself with the pan tilt zoom and image of the Figure 5 10 shows how all of these pieces break apart and then are reformed to create a pan tilt zoom system Then by combining the controlling GUI s for the actuators and an image display both cameras can be controlled from the same GUI without modification to the GUI code See Figure 5 11 to see the two cameras being controlled by the same interface The approach applied to PTZC can be extended to other automated systems 75 Sensors HTTP YO elco Axis gl Pan Motor Controller Tilt Motor Zoom E ay Control Pan Tilt zoom Camera Wind Sheild Whiper ALLELE Sensors Serial I O Pan Motor Actuators Tilt Motor Zoom Control eje ela Figure 5 10 Schematic of a pan and tilt zoom camera 76 Figure 5 11 Pan and tilt zoom from the Pelco camera 77 5 2 5 2 Movement2D The Movement2D class creates a way to control any robot that moves in
17. done by the client In the API remote sensing and control is done as peer to peer The APT also achieves a seamless view of the remote sensors systems and actuators Seamless means that an application cannot tell if the sensor is attached to the local machine or is in fact located several hundred kilometers away To achieve the seamlessness wrapper interfaces and classes are built for both the class and the class listener The interfaces mimic the same functions as the interface or class that is to be used 89 remotely The implementing class of the interface then takes the class that it is to wrap as a parameter Whenever the remote class gets called it passes the call to the local version and then sends the result back to the remote caller This is done for everything except the event listeners Event listeners require too much bandwidth and resources to be passed to the server to be effective and that puts more strain on the server A light weight listener listens to the local events and then passes those to the client object designed for receiving the events The client object then propagates the event to it listeners The API requires four classes to be created for this to effectively wrap an object and a listener two classes for the server and two for the client An example will demonstrate how this works on the sensor class Head ingSensor and HeadingSensorListener Class HeadingSensor gives the heading of a sensor it also provides a
18. how this works mathematically a few things need to be defined A set of actions can be defined as a function of a set of senses equation This describes an entire automaton when the set of senses is the set of all senses and the set of actions applies to all actuators A set of senses can also be defined as a function of a set of senses equation This type of function represents processes or filters on the senses manipulating the information to a new form Converting the position data into heading data represents this type of function Through substitution a set of actions can be constructed from a function that filters senses equation 5 3 Also a set of actions can be constructed from a union of filters equation 5 4 A system is then defined as either a f S or a g S binding the sensors to the actuators through control algorithms Systems can be used by other systems or systems can be combined to create another system A system does not need to know the entire problem only its own part of the problem This allows for smaller less complex code which can perform more complex tasks such as waypoint navigation Let the actuator driver code be the function f the sensor driver code be the function h then there exists a function g such that A f g h world that is independent of driver code Functions f and h represent a hardware abstraction layer and g represents the logic needed to control a system This is the idea behind how the code wor
19. in combination with the position and heading to detect obstacles and then calculates the safest angle to move toward This is a very simple solution but works at least sometimes Obstacle avoidance still needs work but this allows for a simple avoider This has been tested on a Desired Position Nomadic Scout trying to move around a trash can Distance Sensor Position Heading Sensor Sensor a Desired Vector e a Navigation Obsticle a Avoidance Vector Detection 4c ontrols Movement 20 Figure 5 13 Navigation working with obstacle avoidance Aware Navigator An aware navigator acts similar to a navigator it represents any navigator that knows its position heading and target It will use this information to calculate the distance to the target and how far off the heading is This can be useful to a human driver by displaying the adjustments to be made 82 5 2 5 5 Mobile Radar Navigator A mobile radar plans out what point A and point B are for a Navigator The mobile radar rises from the need for the rover to perform SAR movement patterns The mobile radar has four simple commands to control the navigator with Stop Moveto Monostatic and Bistatic The Stop command tells the navigator to stop The Moveto command tells the navigator to move to a Point2D location and then stop Monostatic mode takes two points the first point is where the rover should
20. laptop Optionally the scout can carry a Garmin handheld GPS and a gyro for outdoor testing and calibration A picture of Bob can be seen in Figure 431 127 121 7 2 1 Nomadic Scout A nomadic scout breaks down into the following sensors and actuators two wheel motors one on the left and one on the right a dead reckoning system provides position and heading a sonar array that creates a distance sensor and is surrounded by a series of bump sensors 28 7 2 2 Sony Vaio Picturebook A Sony Vaio Picturebook laptop was used as both the laptop to control the vehicle and as a camera for remote viewing The laptop had a small enough footprint to sit on top of the Nomadic Scout without interfering with its operation The code took a little while to start running but once started would run without any problems The camera on the Vaio was used as an image sensor using JMF The data from the camera was not processed but instead used for remote viewing through the use of the Remote Transfer Protocol RTP built into JMF 43 45 7 2 3 Optional Equipment Bob was also used to devices that would be place on MARVIN These were not essential to bob s operation but provided a way to check the software involved with the operation of MARVIN 7 2 3 1 Garmin GPS Bob was equipped with a Garmin handheld GPS for outdoor testing By using the GPS as a position and heading sensor code could be easily tested Also the accuracy of the GPS with
21. oil upon returning In either location synthetic oil should be used as it has a longer lifetime 4 3 4 Engine Weather Kit The Kohler engine in the Buffalo has a winter weather kit The kit takes the heat from the exhaust and transfers it to the incoming air The heat transfer melts the snow and keeps the engine warm and oil flowing The air filter is also enlarged to filter out any stray snow particles Unfortunately the kit does not fit on the engine while in the Buffalo 51 5 Software In addition to hardware design the rover requires software co design The software design should be portable and robust and should allow for remote sensing and control In terms of portability the code should run on any operating system and be flexible enough to control and understand a variety of sensors and actuators It is also important in field robotics to test in a controlled environment If a system design allows for porting to an indoor robot and actuator control through simulated sensors many faults can ve detected and fixed 5 1 Background A number of research efforts have worked on software designs for controlling robots JAUS Joint Architecture for Unmanned Systems spearheaded by the Department of Defense seeks to cover all possible control systems needed for vehicles This includes Uninhabited Air Vehicles UAVs Uninhabited Ground Vehicles UGVs Uninhabited Underwater Vehicles UUVs and the like JAUS uses a hierarchy inv
22. platform selection considers the requirements needed to survive arctic conditions as well as space needs among other constraints During selection possible vehicles are compared to the requirements The thesis includes a brief look at simulation of some of the platform designs The actuation of the platform covers all the steps of bringing the selected platform under computer control Tasks include motor selection and installation and choice of hardware to use for computer controls Winterization focuses on the need to control the environment inside the rover This process covers building a shell and protecting all the gaps which snow can get in The software control system examines how to design a hardware abstraction layer for automated systems The software is used to perform waypoint navigation on multiple platforms The UGV in this thesis is being used as part of the PRISM project and it will help to move and position radar equipment The current stage of the UGV is as teleoperation but will be extended by the end of project to a fully autonomous vehicle That is it will perform waypoint navigation obstacle avoidance on the way to the point and finally understand how to move based on the tasks assigned to it 1 2 PRISM What is PRISM PRISM stands for Polar Radar for Ice Sheet Measurements 20 The goal of the prism project is to measure the thickness and other characteristics of ice sheets using radar A synthetic aperture radar
23. safe control 43 123 7 2 7 Waypoint Navigation In the lab a 3x3 meter grid of tape was built Bob would be placed at the center and told to move to one of the points such as 1 1 Bob was given an error tolerance of 15 degrees and 0 3 m distance accuracy Bob managed to navigate to the desired locations At first the turning speed was set too high and bob would oscillate turning sharply to the left and then right and back to the left trying to get within the threshold Eventually a very small turn speed was used and worked well 7 2 8 Mobile Radar Navigation The next test was to start Bob at one of the corners and give the command to do a 3m by 1m SAR movement This would test to make sure that the code produced the correct values for bob to move to Bob moved perfectly to with 3m of the target before heading off to the next target So well in fact that Bob needed to be carefully watch so as not to run out of the grid and into a wall 7 2 9 Obstacle Avoidance Obstacle avoidance was tested using a trash can as an obstacle The sonar sensor proved rather unreliable and the large distance between them made it difficult for Bob to properly navigate around the trash can instead of hitting it on the side Eventually the safe heading was raised to a point that Bob would avoid the trash can and remain on the waypoint path 7 3 MARVIN 2003 Results In summer 2003 filed season MARVIN was tested to make sure that the vehicle a
24. sensor is mounted at an extremity of the vehicle Likewise a gyro drift over time the gyro eventually is off from what the true value should be By combining these two sensors into one heading sensor both problems can be 85 Figure 5 15 Spiral movement pattern State Calculation Next State Initial P Po Py Py P Pe 1 n 2 Po P gt Pe Pe w m 2 Ps Pz Pe Pe 1 n 1 Py P4 Pe Pe w m 1 P Pe Current waypoint l Po Py length wW P Po width r Turning radius n 2 r l Used ifl jr m 2 r w Used if w jr Table 5 2 Spiral state transition calculations 86 eliminated The heading of the gyro can be corrected when moving forward by the position sensor and then the gyro can be used as the heading while turning to eliminate the position problem Combining these two sensors can provide highly accurate heading information This was done to provide the rover with a much better heading sensor 5 2 5 7 Systems In general the systems designed and implemented as part of this project provide a way to control an autonomous system from the motors up including reaction level reasoning to full planning All of this is done without the need to compensate for hardware specific problems as there are parameters to the systems as a whole and can be measured learned or adjusted by humans The systems need not be limited to just what is presented Things li
25. velocity can be controlled by using the brake and throttle and side velocity by using the steering wheel This class is not implemented as there is no vehicle of this type available to test Other There is also a null controller that controls no motors but is useful for testing systems that use sensor data to check if they are sending the proper left right velocities to drive properly Other types like walking robots could be controlled by controlling how the legs move this would also allow for strafing motion which is not possible in wheeled vehicles 5 2 5 3 Joystick Control Now that any ground vehicle s motion can be seen as just forward and side velocity the vehicle can be controlled through a joystick The Y axis is used for forward velocity and X axis for side velocity control The Movement2D class can be queried for min and max values which are then interpolation on the joystick s min and max values Very simple and a very small piece of code that works for controlling both the Nomadic Scout and MARVIN depending only on which type of Movement2D 80 is passed to it A human operator needs only decide which vehicle to control and then move it using a joystick 5 2 5 4 Navigator A navigator calculates how to get from point A to point B and then uses a Movement2D to get there Upon arrival a navigator will send an event to all of its peers letting them know it has arrived A navigator requires that any sort of contr
26. which navigator to watch the track button forces the center of the map to follow the selected navigator The current position is display just below if gps is available it is displayed otherwise just x y is display Waypoints can be opened from a file and are placed in a list the arrows move through the list updated on the map the target heading Waypoints can be added removed and saved to file for future use Below the waypoints is the actual distance to the target in a direct line The current heading and target heading are displayed side by side Aligning the two lines provides a straight path to the target And finally the distance to any other navigator can be selected 118 amp Navigtor Display Test m a E T Watching e z Track Current Position x Y 1 0 41 0 Way Points X Y oan 1 0 Open Save SaveAs Add Remove Distance To Target less to Target 6 325 Current Heading Target Heading S SE Zoom Out Figure 6 21 Information display window for a human to track vehicles and distances between them 119 7 Evaluation Testing MARVIN took place in Kansas and in Greenland For individual testing all of the equipment was placed into a temperature chamber at 30C for 24 hours while running Then the equipment w
27. 004_4_31_0_19 54 log Greenland topcon_2004_6_14_6_58_13 log topcon_2004 6_15 3 30_16 log topcon_2004_6_15_3 49 47 log topcon_2004 6 15 3 54 49 log topcon_2004_6_17_8 48 28 log topcon_2004 6 _17_9 58 29 log topcon_2004_6_18_3 9 49 log topcon_2004_6_19 3_49_10 log topcon_2004_6_21_1_10_49 log topcon_2004 6 21_11_6 8 log Table 7 1 Raw waypoint data Waypoint X Waypoint Y 303547 6 4314105 303496 91 4314038 33 303547 6 4314105 303496 91 4314038 33 303547 6 4314105 303496 91 4314038 33 303547 6 4314105 303547 6 4314105 303567 6 4314125 303547 6 4314105 303577 6 4314105 303577 6 4314095 303520 434105 303507 6 4314105 303547 6 4314105 303547 6 4314085 303527 6 4314085 303527 6 4314105 303507 6 4314105 303507 6 4314085 Average Standard Deviation 517690 44 8054050 12 517690 44 8054050 12 517690 44 8054100 12 517690 44 8054050 12 517690 44 8054050 12 517690 44 8054050 12 517690 44 8054050 12 517690 44 8054080 12 517710 44 8054080 12 517710 44 8054050 12 517690 44 8054050 12 517690 44 8055100 12 517790 44 8054600 12 517790 44 8054100 12 517740 8054990 517690 44 8054550 517690 8054050 517690 8054100 517702 8054100 517702 8054050 517691 8054050 517691 8054100 517703 8054100 517703 8054050 517692 8054050 517692 8054100 517704 8054100 517704 8054050 517693 8054050 517693 8054100 517705 8054100 517705 8054050 517694 8054050 521101 8057534 521174 8057602 521182 76 8057610 16 521109 76 805754
28. 2 16 521101 73 8057534 68 521174 73 8057602 68 521183 49 8057610 84 521110 49 8057542 84 521102 46 8057535 36 521175 46 8057603 36 521184 22 8057611 52 521111 22 8057543 52 521103 19 8057536 04 521176 19 8057604 04 521184 95 8057612 2 521111 95 8057544 2 521103 92 8057536 72 521176 92 8057604 72 521185 68 8057612 88 521112 68 8057544 88 521104 65 8057537 4 521177 65 8057605 4 521186 41 8057613 56 521113 41 8057545 56 521105 38 8057538 08 521100 8057490 Average Standard Deviation Overall Average Standard Deviation Distance from Target Distance from Line Distance Traveled 3 62 0 43 0 33 2 99 1 63 0 92 1 56 0 47 2 64 2 03 1 09 2 56 2 11 0 729613 1 25 1 37 1 076 2 77 1 45 171 1 63678065 0 918476806 2 1 1 06 2 35 2 25 0 21 1 04 1 14 2 53 1 79 0 36 6 27 1 079 0 98 3 67 3 92 3 63 3 35 2 82 3 78 3 42 3 78 2 73 3 49 3 89 3 62 3 82 3 99 37 375 3 44 3 93 263 3 66 3 98 2 66 3 31 3 68 5 37 3 37 2 83 3 47 5 36 376 3 39 3 73 5 49 2 476 3 23 3 63 7 24 3 65 7 24 3 66 5 93 38 2 54 3 246186441 1 504184158 2 838741937 1 543997 149 158 4 87 4 9165 16 78347458 21 69742576 13 77917722 19 55614746 42 85 93 25 83 75 83 75 89 06 38 549 2723240541 50 110 11 97 99 76 10 97 99 76 11 97 99 76 10 97 99 76 11 97 99 76 10 97 99 76 11 97 99 76 10 97 99 76 11 97 99 76 10 97 99 76 11 97 99 76 10 97 99 76 2112 65 134 3680847
29. 4 Figure 2 18 CMU s Nomad 24 2 2 5 2 Dante Dante I and II built by CMU are legged robots designed to climb into a volcano A walking robot has the distinct advantage of being able to maneuver over more types of terrain than a robot based on wheeled locomotion This advantage however is not much of an advantage when the terrain is endless snow and ice A legged robot would need to have snow shoes That is the pressure from a leg would need to be distributed across fresh snow to prevent the robot from sinking beneath the surface of the snow A walking robot would provide an easy way to stop and position the radar since the mobility would not be as limiting as wheeled power vehicles They are also typically slower than wheels but speed is not as great of a factor as getting the alignment of the radar Dante used a laser range finder and array of cameras to help it navigate and map out the inside of volcanoes 2 2 5 3 Mars Rover NASA s Spirit rover is another example of a custom robot designed for a specific task In this case the rover explores Mars The rover uses a six wheeled drive system The drive system allows for great flexibility for going over rocks and bumps keeping the robot stable Figure shows a picture of the Mars Pathfinder 25 25 Figure 2 19 CMU s Dante II 26 y Pancameapair Rover Pancam Equipment Low Gain Calibr Deck RED Antenna alibration Target E A Naveam
30. 6 2 1 Topcon GPS IN 97 dde a e de dra 97 PER A 103 a 104 6 2 5 Pelco Camera Axis 2400 Video Server 104 E EEEE E E E ae Me ee 105 PAE lt e oca pra aap dede ee eh 105 6 3 Weather Proofing 2 44 44 Lis Da cra 6s es 105 AA AA 105 AE EEE 108 6 4 Finished Product psss tra 6 ay A sure 113 EEE en 115 6 5 1 Position2Heading Sensor 115 5h ha D ee 115 6 5 3 Joystick Control ocres Kee ERK MERE ESS 115 ee a ee Se pe Se 116 6 5 5 Obstacle Avoidancel 116 65 6 Mobile Radar rs sun pisos dass oS 116 6 5 7 Remote Control 117 6 6 SAR Tracked Vehicle ena dera a e 117 6 6 1 Topcon GPS aaa A o 20 117 bi be et rina a de ed 117 vii T Evaluationl 4 4 4 120 eB On 2 D ee ee ee rey G 120 7 2 Testing Platform Bob 4 cascada laca dates de 121 7 2 1 Nomadic Scout 444 4 sait sait rues 122 7 2 2 Sony Vaio Picturebook Less odo ee dado sets 122 7 2 3 Optional Equipment 122 7 2 3 1 Garmin Listes hi un era 122 7 2 3 2 MotionPak Il 44 4 4444 Un 123 7 2 4 Local Joystick Control o soccer mes 123 1 2 5 Remote Joystick Control o 4 5 64 6864 be 464 123 7 2 6 Remote Sensing 123 aoa dd no wee aa A 124 IES A 124 7 2 9 Obstacle Avoidancel 124 7 3 MARVIN 2003 Results oeste ey EEG eR EE SH 124 7 3 1 Vehic
31. Available http www maxatvs com buffalo interior htm E Rollins J Luntz B Shamah and W Whittaker Nomad A demonstraion of the transoforming chassis 1997 Rybinsk Motors The taiga snowmobile 1999 Onlinej Available http www rybinskmotors ru old English tayga htm D Selvarajan Implementation of real time java using kurt Master s thesis University of Kansas 2003 Sheffield Plastics Inc Hyzod product data 2004 Online Available http www lehighvalleyplastics com pdf hyzod pdf Shindaiwa org Shindaiwa egr6000 and egr6000e generator 2004 Online Available http www shindaiwa org shindaiwa generator htm SICK Laser management systems Technical description Germany 1998 Sno Conversion Inc Sno traxx 1995 Online Available http www snowtraxx com 163 41 Sony Color video camera Operating instructions Evi d30 evi d31 1999 Online Available http bssc sel sony com Professional docs manuals evi d30instructionmanuall 1 pdf Evi d30 d31 command list 1999 Online Available http bssc sel sony com Professional docs manuals evid30commandlist1 21 pdf 43 Using your sony viao picturebook computer 2004 Online Available http www docs sony com release PCGCIMV PDF 44 R S Stansbury Integration and evaluation of sensor modalities for polar robots Master s thesis Univ
32. Book Max laptop was chosen shown in Figure 6 6 The GoBook exceeds the military specifications Using a Pentium III 700 Mhz with 256MB of memory proved sufficient to run both the control software and the feedback interfaces 19 95 Figure 6 2 Motor mount design front view 96 Throttle Motor Figure 6 3 Replacement seat design 6 2 Sensors 6 2 1 Topcon GPS MARVIN relies on a Topcon GPS which when in Real Time Kinematic RTK mode provides centimeter accuracy The GPS is also used as a heading sensor when MARVIN is moving forward Figure shows the rack mount box that holds the Topcon GPS receiver The GPS is represented in software as a GPS Sensor Heading information is gained by utilizing the Position2Heading Sensor class 47 6 2 2 MotionPak II Gyroscope As discussed before the GPS alone does make a good heading sensor so a MotionPak II Gyroscope provides heading information when MARVIN is turning 97 Figure 6 4 Installed actuators 98 Steering Motor 0 2 0 2 0 4 1 2 1 4 1 6 1 8 Dista nce m Throttle Motor 0 3 0 2 0 1 0 g 0 1 5 3 0 2 0 3 0 4 0 5 0 6 0 000 0 001 0 002 0 003 0 004 0 005 0 006 0 007 0 008 0 009 0 010 Distance m Figure 6 5 Power required to control MARVIN Samples every millimeter of movement Figure 6 6 Gobook Max covered in ice after being dropped on the snow 100 Figure 6 7 Topcon GPS rack m
33. DESIGN AND CONSTRUCTION OF A ROBOT FOR POLAR REGION NAVIGATION By Hans P Harmon B S Computer Science University of Kansas 2001 Submitted to the Department of Electrical Engineering and Computer Science and the Faculty of the Graduate School of the University of Kansas in partial fulfillment of the requirements for the degree of Master of Science Arvin Agah Committee Chair Costas Tsatsoulis Committee Member Chris Allen Committee Member Date of Acceptance ABSTRACT This thesis presents how to build weather proof and control a robot to perform waypoint navigation in polar regions Several platforms are analyzed for the ability to survive polar environmental conditions the ease of automation payload capacity and space available for extra equipment A base platform is selected and then analyzed to determine what is required to actuate the driving of the vehicle The selected vehicle then undergoes winterization determining what modifications allow the vehicle to perform in polar regions A weather proof enclosure is built to protect instruments on board the platform Control software then performs waypoint navigation on a test platform and the main robot in both Kansas and Greenland ACKNOWLEDGEMENTS I would like to acknowledge the contributions support and encouragement of others who have helped me to complete my thesis I would like to recognize my thesis chair and adviser Dr Arvin Agah for giving me
34. DO aai da OR a e ES 57 d a a e eS 58 5 2 2 3 Heading A DR AU Das eus de 59 I Ne de en a a E 61 5 2 2 5 Temperature use ha rt a Niue ia 61 PRA A 62 Def DUMP A 65 3 2 2 8 IMABE 4 yt den ba das dada ads 65 5 2 2 9 Other Sensors 22s see ee ee 4e 2 65 5 2 3 Extension to Sensor 4e eedie aan 406 66 5 2 3 1 Simple Sensor 4 lt lt a eee sa eee sua 66 5 2 3 2 Logging and Logs as Sensors 66 5 2 3 3 Remote Sensing 67 524 ACTA MON suce Sue Ra ne eee E OR ne HRS 68 5 2 4 1 Non ia ein un side een es 69 5 2 4 2 Switehes 84 6 aa se sain ses rs 6 70 5 2 4 3 Null Actuators een e sure eS 70 PE IET 71 0 2 0 1 Pan and Tilt Zoom Camera 72 5 2 5 2 MOVE MEA on o a ee wk A at 78 5 2 5 3 Joystick Controll 4 4 amp 4 4 44 ke we 44 80 ee ra AR A a ee 81 5 2 5 5 Mobile Radar Navigator 83 5 2 5 6 Sensor Fusions i 6 6 5 60 9 dia 4 ae ne we 85 oA ot be ee te dadas beto 87 5 2 6 Health Monitoring 4 n en we era ares eS 87 5 2 7 Event Handling ss eo ad a Pe eae DS e de eo 88 vi 5 2 8 Remote Sensing and Controll 89 CIO AAA AA 91 AE E e 93 SD VUE e e add 93 ENS a aa NAAA oui no te 93 61 2 PONT econ Di a ua die le ride cure 94 6 1 3 Actuators Linmot Motors 94 6 1 4 Computer GoBook Max Laptop 95 PE Made dan he ie Gi e Leu 97
35. I s ese oe ns dieu loin dre 26 ac o e D A sd a a dd ce ek 27 2 21 The original Buffalo prior to modifications 33 xi 3 1 Lever controls for skid steering driving for a MaxATV 35 3 2 Force Five force measuring tool 36 3 3 Posible motor points ere rs mask Pia a da da 37 4 1 Scale carbon fiber shell 47 42 Automotive weather stripping 49 5 1 API design A oe a oe wh Se RR ARES ERAS ER 55 5 2 Position display amp 4 44 Leu Lu Ree oe den ads adeeb D8 5 3 Aerial photo adjusted for use in a GIS system 60 5 4 Heading sensor display y usas ars AUS rr ee area 61 5 5 Tilt sensor display 4 4 4 444444444 0 ha rieron 62 5 6 Temperature sensor display 63 5 7 Distance sensor is the outline a small line from the center shows Ta 61 5 8 Actuator class hierarchy 68 5 9 The PTZ Cameras 4 ee a we a da RE eS 74 5 10 Schematic of a pan and tilt zoom camera 76 nse th Gu ao a HBR ed wed 77 mo Ge he oa we ee eh an ee Ae e 79 5 13 Navigation working with obstacle avoidance 82 5 14 S curve movement patterm 2 4 44 4 4 sua dun du dure 84 5 15 Spiral movement pattern 86 xii 5 16 Remote wrapping of a sensorl 92 6 1 Motor mount design side view
36. a variety of filters are available Using air filters requires a way of attaching them to the vehicle Tape or bolting slide rails could be necessary 4 3 Engine Adjustments Both the vehicle engine and the onboard generator will need to be modified to handle the cold weather and reduced availability of oxygen at higher altitudes In addition the generator must be able to vent exhaust especially if there is a human occupant 4 3 1 Generator Exhaust The generator exhaust needs to be vented to the outside If the generator is in a different compartment from the main engine it would require building a dedicated exhaust pipe 4 3 2 Re Jetting Both engines will need to be re jetted Re jetting the carburetor allows more oxygen flow in with the gas and causes the proper mixture With too much oxygen 90 the gas will burn rich causing soot to appear on the spark plug eventually causing them to not work With too little oxygen the gas will not explode and the engine will flood In either case the vehicle would not function Since the vehicle must run at both sea level and 3000 meters above sea level different jets will be needed for each location 4 3 3 Oil Oil prevents the wear and tear on the pistons of the engine It must be able to flow properly in the cold or the piston will get sticky and have to work harder For both engines the oil should be changed to low temperature oil before leaving and replaced with warm weather
37. about the motor but maybe that information is not needed Three types of switch are defined 1 A binary switch has only two states on and off This can represent a light switch or a transistor Either something is running or it is not Power switches or things like X10 appliance modules fit well into this category 2 A momentary switch has an off state but will automatically change back to an on state Things like reset can represent using momentary switches 3 A linear switch controls anything that has a single range of values To get more than one dimension of control a linear switch is used for each dimension A linear switch can be used to control a dimmable X10 controller or the voltage to a device or other applications where there is a needed range of values 5 2 4 3 Null Actuators Sometimes it is useful to have nothing happen this is what null actuators are for Null actuators allow higher level logic to think that it has acted when in fact 70 nothing has happened This is useful with simulated data or testing higher level logic without endangering a field robot by putting it in the field Using this with sensor logs allows for a powerful logic simulation environment There will still need to be adjustments for the real world but with the logic worked out this will take less time 5 2 5 System Sensors and actuators combine to make systems Systems use other systems to create higher level systems To describe
38. acks the amount of information that can be gathered from a GPS Device The GPS Sensor in this hierarchy extends the PositionSensor by adding the notion of height and time The Point2D becomes insufficient so GeodeticDatum is used instead GeodeticDatum utilizes information like that in a GIS Geographic Infor mation System GeodeticDatum stores not only the x and y of the geological coordinate system but also the reference ellipsoid used to gather that information The datum can store latitude and longitude and this can be transformed into the more useful Universal Transverse Mercator UTM format UTM coordinates divide the world into pieces that are on a cylinder instead of a sphere This looks more like what a flat map of the Earth looks like instead of a globe The advantage of using UTM coordinates is that they are in meters This makes it easier to track distances and compute the next position if all that is known is to for instance move north 100m GeodeticDatum is an abstract class that extends Point2D by adding height and time GeodeticDatumUTM and GoedeticDatumLatitudeLongitude are instantances of the GeodeticDatum and each can be transformed to the other 58 or even transformed onto the needed ellipsoid The extension from Point2D means that anything that listens to just the position can get the geodetic data without needing to do any conversions If an application relies only on the position it can look at the GPS as a Positio
39. an the 16 sonar sensors of Bob 39 6 2 5 Pelco Camera Axis 2400 Video Server A Pelco Espirit camera shown in Figure 6 11 was mounted to the top of MARVIN along with an AXIS 2400 camera controller The controller provides a Web interface to viewing and controlling the camera The camera captures image video and through software panoramic at various angles The camera is there for 104 remote viewing and it is not very useful for detecting obstacles especially snow obstacles like sastrugis and crevasses 29 9 6 2 6 WS2000 Weather Station The Rainwise WS2000 weather station provides information about the outside weather of MARVIN It includes a temperature sensor and a weather sensor The weather station is entirely for monitoring and logging weather and possibly could be used to determine bad weather conditions as a health system Figure 6 12 shows a picture of the weather station 32 6 2 7 Fuel Sensors Fuel sensors though obtained have been coded but were not installed on MARVIN and therefore not used 6 3 Weather Proofing 6 3 1 Shell The protective shell was designed out of t slotted extrusions with Alucobond and Hyzod to fill in the holes in the frame The t slotted extrusions allow for adjustment of design as the placement of some antennas is not yet known Alucobond is a light composite material consisting of two aluminum cover sheets and a core made of plastic The Alucobond provides a light weight
40. and strong material that will also help to reduce electromagnetic noise leaking from or into the vehicle Hyzod an upgrade from Lexan provides protection to any human passenger while allowing them to see out 371 3 The shell of the vehicle creates a 2mx2mx3m box that rests on top of the base The frame screws into the bottom half and cross members rest along the bed to hold the frame in place The cross 105 Figure 6 11 Pelco Espirit pan and tilt and zoom camera 106 Figure 6 12 Rainwise WS2000 weather station members also provide the framework for a rack mount area that can hold 40U of rack mount equipment Two other cross bars support the generator and allow it to be bolted into place The height of the box allows a human to get in and out through the front doors The generator and equipment can be accessed from sliding doors on the sides and back Figures through show how the frame fits together all values are in inches Figure 6 13 Frame front view measurements in inches 6 3 2 Sealing The Hyzod and Alucobond fill in the large holes in the frame but leave small gaps around where placed especially around the doors To fill in the gaps a combination of using a rubber seals to lock the sheets in place and then using silicone gel on the other side to make the seal water tight was used The silicone gel also served to fill in around bolts and screws The doors of MARVIN are sealed with automotive weather proo
41. as powered off and let sit for another 24 hours and then powered on This tested for weather specifications After individual testing and calibration with software the actuators and sensors were installed in the ATV and field tested Field testing took place at a terrain park and an open field in Kansas Finally MARVIN was tested in Greenland During the field season of 2003 joystick control and individual sensors were tested for workability in the polar region During 2004 waypoint navigation requiring that everything work together was tested along with SAR pattern movement While not in the field code was tested on Bob and simulations were performed to help understand the environment and possible obstacles 7 1 Simulation Simulations of various types of vehicles with proper weight distribution were performed The simulations provided access to the visualization of possible problems that could occur on the ice The simulations helped in determining the turning radius that would prevent MARVIN from driving over an antenna as well as at what size does an obstacle become too large for MARVIN to simply go over 2 120 Figure 7 1 Bob doing waypoint navigation in the lab 7 2 Testing Platform Bob Bob a Nomadic Scout robot provides a platform for testing the reactionary and planning parts of the code without needing to take MARVIN into the field The entire system consists of a Nomadic Scout robot being controlled by a Sony Vaio
42. ase Selection This chapter explores the different possible base platforms for creating a UGV for polar environments The first step to selecting the proper vehicle is to start by looking at the requirements need to perform the given task Then individual vehicles types and robotic platforms are analyzed The analysis includes the satisfaction of the requirements and what will be required to fix any failings in requirements Finally other projects related to converting vehicles into UGVs will be examined 2 1 Requirements The first requirement of the mobile platform is the ability to drive on snow and ice without slipping or getting stuck while carrying maximum load of 300kg It must operate in a temperature range of 30C to 40C and altitudes from Om to 3000m above sea level Not only should the vehicle drive on snow and ice but it should also handle dirt and grass as much of the testing is performed in Kansas Minor modifications between running in each environment such as changing the engine s carburetor s jets are acceptable but major changes like changing ski to tires or vice versa are less desirable In addition to working in a wide range of temperatures and altitudes the base platform must be able to carry the maximum load of equipment measured by both weight 300 kg and volume 40U s of rack mount space The equipment onboard includes the radar system automation controls power system communication equipment and a weather cov
43. ce JMF provides a way to get images from any capture device audio or video on Windows Linux and Solaris operating systems JMF also provides a way to stream to images save to disk and a number of other functions The images from JMF can be displayed to GUI much like any other image this will allow for a GUI that works on both the EVI D30 and the Axis2400 45 42 13 73 Linear e ad Controller Zoom Pan Tilt Zoom Control System Tracking System Figure 5 9 The PTZ camera 74 The Axis 2400 provides controls to the camera through a web interface like wise the images are queried from the server This gives a blank response so that a web page does not change the page Like the EVI D30 the actuators communicate through a controlling class The controlling class forces synchronization with the server so as to not overload or send confusing messages The image is retrieved through an HTTP request as well The image is returned in Jpeg format Java provides a Toolkit class to load Web images but this does not provide a method of actually saving the image at Jpegs so instead of using the Toolkit a custom WebDataLoader class is used This differs from the toolkit by propagating an event as to when an image is loaded and ready for anyone to use The event provides the actual bytes of the image so that any listener can write the data to disk or display to the screen as an Image class This also means the loader can be used by
44. ce the current system relies on humans to do part of the driving there is a need to give the human an idea of where both components transmitter and receiver of the SAR are and what targets they are aiming for A human fits in right with being the navigator and the movement2D of the system In the case of a human predefined waypoints are given and plotting on a map along with using GPS for position and heading sensing 6 6 1 Topcon GPS The same GPS with centimeter resolution is also given to the human and provides both heading and position 6 6 2 Heads Up Display A human has difficulty interpreting the raw data from the sensors and from the rover Instead a heads up display is used to show any number of vehicles The vehicles are plotted using UTM values with a line showing current heading Any vehicle can be selected from a list and this GUI will show the waypoints for that vehicle along with its current position heading and target heading A second list allows the user to get the distance from another vehicle The Interface allows the human to collaborate its efforts with any number of rovers This also doubles 117 as a way to track progress of MARVIN when on its own Figure shows the display to be used by the collaborating human s The left side of the GUI shows an overhead view with coordinates on the side The zoom level and center position of the map are controlled by the buttons in the lower right The top combobox sets
45. cted for the project This choice resulted from a number of factors The specifications showed that the Buffalo would perform the tasks needed A vender provided the opportunity to test drive and examine the internals After inspecting the vehicle it became quite clear that its simple yet durable design would prove easy to automate as well as easy to maintain The Buffalo was also ordered with the full weather kit and tracks Figure shows the vehicle as obtained with no modifications 33 3 Actuation After selecting MaxATV s Buffalo amphibious ATV it was time to further analyze the vehicle and choose a method of converting it to a UGV The Buffalo a skid steering vehicle is controlled by two brakes and a throttle The throttle controls overall speed while each brake causes half of the vehicle to stop allowing it to make tight turns Actuating this type of control system involves placing motors on the throttle and each of the brakes However there is the questions of what motors to use and how to mount them 3 1 Requirements The question of actuation is not just a question of motors but how to control those motors and the ability of all components to satisfy the given constraints of the system as a whole The system as a whole comprises of motors motor controllers power supplies and software to run the system Figure 3 1 shows the drive system for the vehicle The first requirement of the motors is the amount of force that
46. d be air tight as the engine and on board equipment will need to vent out generated heat 4 2 1 Rubber Rubber strips can be used to cover larger gaps of two to three inches Larger gaps occur mostly where doors come together or where the edge of the shell does not exactly fit the vehicle The seals must be bolted on and will still leave behind some small gaps that require a different solution 48 Figure 4 2 Automotive weather stripping 4 2 2 Automotive Weather Stripping Automotive weather stripping as seen in Figure 4 2 requires pressure to maintain to form and maintain a seal The stripping is applied by removing the backing and pressing into place It is useful for areas that lock and seal like doors or equipment holes 4 2 3 Silicone Silicone gel comes in a tube and can be applied anywhere on the vehicle It fills in holes and hard to reach areas Upon application the gel should be smoothed down to prevent lumps that can snag and eventually remove the seal 49 4 2 4 Quick Weld Quick weld like J B Weld or metal epoxy bonds to metal It does not hold as well as a true weld but is quicker to apply easier to transport and can get into the cracks of the metal Quick weld does not bond well to smooth surfaces 4 2 5 Air Filters Air filters block dust particles and snow The air filters will let oxygen into the vehicle and removing heat while keeping out the snow Most air filters are prepackaged and
47. e Currently a few heading devices exist in code each unique in providing heading A TCM sensor provides heading in the form of a magnetic compass reading A Nomadic Scout robot provides heading through the use of a dead 99 Figure 5 3 Aerial photo adjusted for use in a GIS system 60 reckoning system The MotionPak II gyro provides heading through use of accelerometers Finally a position sensor can provide heading through the Position2HeadingSensor class A simple GUI now be used to display heading from any of the sources and it would look the same Figure 27 Heading 60 8 Figure 5 4 Heading sensor display 5 2 2 4 Tilt The tilt sensor covers pitch and yaw This is a two dimensional sensor with one value in each dimension If combined with a GPS and Heading sensor all 6 degrees of movement are covered Pitch and roll are given in degrees The TCM and MotionPak II provide tilt the TCM uses a fluid and measures current where the MotionPak II again uses accelerometers See Figure shows a screen shot of pitch and roll 5 2 2 5 Temperature Many devices provide temperature as a source of information as well as for internal health reasons Temperature can also be used for weather data as well Temperature has only one dimension and one value which by default is given in Celsius but can be converted to Fahrenheit 61 amp Tilt Sensor GU ES Figure 5 5 Tilt sensor display Again the TCM and Mot
48. e but are driven by the exact same code save the drivers The other computers are used to test remote functionality on both rovers 91 Application Sensor Interface Remote Sensor Interface Remote Sensor Sensor Bridge Remote RMI Local RMI Physical Device Figure 5 16 Remote wrapping of a sensor 92 6 Implementation This chapter describes the detailed approach to build MARVIN the autonomous rover This includes what was done where and how sensors actuators and weather proofing were installed All parts involved must be able to survive in temperature ranges from 40C to 100C This is to insure that MARVIN will work properly in the arctic environments Most equipment should also be able to withstand a little bit of water from melting snow 6 1 Actuation To build MARVIN the tasks include obtaining a mobile platform bringing the vehicle under computer control and powering all of equipment within the vehicle 6 1 1 MAXATV The base vehicle chosen was a Buffalo MAXATV from Recreative Industries 33 The vehicle with its amphibious nature lent itself better to winterization This in addition to the fact that the controls were very straight forward with two brakes a throttle and only forward neutral and reverse gears During a test drive of the vehicle everything seemed intuitive to controlling and mechanics of the vehicle were fairly simple Price wise the Buffalo was a bit more expensive bu
49. e ee a Aa eS pes Vw oo Ree ee OE Be nl CI si ce a aidr e s sea Bok awe wd 2 2 3 2 UGV Amphibious ATVS 2 2 4 Remote Controlled Tanks 2 2 5 Customized Vehicles 22 NOM 24 as peores BV we eV KERR eH 2 25 2 Dante AAA 2 2 5 3 Mars Rover oa amp o a DRG rba tes a dos as dad lv e W N e he O N N NOA A 3 Actuation As eo D a Ge ee are Se ae eS 3 2 A ATENTEN A AI ON 3 3 1 Mechanical vs Electromagnetic co o e a A a ees ee eee ee eee 3 4 Motor A 3 4 1 Microcontroller 2 sch a a renrerraneas ses a pe a es a ee a a ee ee E a AA 4 1 Protective Shell es L se La mes samir els 4 1 1 Standard Additions sue A a 4 1 2 Carbon Fiber crias dedans desde d 4 1 3 Metall AA Bk BE NES RAT Ets 4 1 4 T slotted Extrusions sisas dis ss LT DEA sem be ee oA ba pad As LPO see yede elk Be EAE rd ces 4 2 2 Automotive Weather Stripping 4 2 3 Silicone A ph ERS eee Se EE eo 4 24 Quick Weld assess ada ao as a 4259 Air ARE A a a ie a ce 4 3 1 Generator Exhaust E e e s ea ack eee E Aoa Oil ra A A OS eT 134 Engine Weather Kit 54 sus 24 du ae die ms 5 Software 52 AR ia ee eee oe ee ee eh ee ee Be ee BES 52 ie ash ge o a al E dir Dre 54 Dll D vicefs mss da a moc AR AA A de 54 5 2 2 Abstract Sensor YS a is A 56 5 2 2 1 P
50. e from the line connecting the starting location to the target waypoint Since the GPS has a relative accuracy of 1cm the measurements are only measured down to the centimeter level 7 4 2 1 Kansas Tests In Kansas the waypoint navigation was tested using a 3 meter and 10 degree threshold to get a target There were a series of tests of MARVIN moving to a waypoint and then tests of MARVIN performing SAR S movement in a 20m by 20m pattern through one full S The S paths were used in the overall accuracy of the vehicle movement as the S is just a series of waypoints to reach A band 130 practice field on campus provided a nice open area to test waypoint without running into anyone Waypoints Waypoint navigation in Kansas was accurate to an average of 1 64 meters with a standard deviation of 0 92 meters with peaks of 3 62 meters and 0 33 meters Overall the distance from the lines connecting the waypoints was 4 92 meters with a standard deviation of 4 71 meters with peaks of 20 4 and 0 89 The 20 4 meter off the line measurement came from setting MARVIN facing 180 degrees from the target causing the widest possible turn Table 7 1 shows the raw data and Figures 7 2 through show the movements of MARVIN on the band practice field The black lines indicate the path traveled the waypoints are shown as the black squares and the stopping point of the vehicle is shown as a grey dot SAR In Kansas a 20m by 20m SAR movement was tested Unfort
51. e throttle Eventually the throttle would be replaced with a larger motor as the cold made things a little tougher to move 22 The actuators were mounted in the middle of the seat using t slotted extrusions to hold them in place Figures and show the design of the structure used to hold the motors in place The seat was replaced with a sheet of Alucobond The original seat after being cut in half was put back in place for a driver The new seat also had a location to place the motor controllers and a laptop Figure shows the seat replacement The actuators themselves attached to the brake lever using shaft collars and pivoting eyehole bolts The bolts combine with the motors only being bolted in the back allowed for enough 94 Figure 6 1 Motor mount design side view slack on the rotation for the motors to work properly The throttle control hooked to a secondary throttle cable to allow for both human and automated control of the throttle Figure shows the motors mounted inside the vehicle 3 In software LinearMotors represent the Linmot motors and the three motors combined to form a Skid Steering Movement2D for control of the vehicle The motors in this configuration had a maximum current draw was 1 8 A Q 72V for the brakes and 0 5 A 48V for the throttle Figure 6 5 shows the current draw versus distance as installed in the vehicle 6 1 4 Computer GoBook Max Laptop To control the vehicle and provide human feedback and Go
52. e to working on grass and dirt These kits still use the track drive as the main source of power for the snowmobile changing the front skis to wheels This has the effect of going from skis to roller skates 49 Sno Pro model shown here in black Figure 2 1 Arctic Cat F5 performance snowmobile Figure 2 2 Arctic Cat Bearcat Widetrack touring snowmobile Figure 2 3 Ski to wheel conversion kit for snowmobiles 2 2 1 3 UGV Snowmobiles Very few projects have been done to automate a snowmobile In 1997 NASA had plans to search for meteorites in Antarctica using multiple robots The plan included the possible use of snowmobiles as the platform as well as a previously deployed robot named Nomad A vision of the system can be seen in Figure 24 In 1999 the Universita degli Studi di Siena in Italy built an UGV from a snowmobile The snowmobile s track drive was replaced with a differential drive system The changes to the drive were made to simplify the control giving the possibility of changing direction with ease and of steering in a very limited space and for a larger surface footprint The goal of the robot was to find meteorites beneath the ice in Antarctica 53 Figure 2 4 Vision of robotic snowmobile system 10 2 2 2 ATVs All Terrain Vehicles ATVs provide enough of horsepower for most applications and work in most terrains Most 4 wheeled ATVs are fairly inexpensive The possibility of an electr
53. eal piece of equipment that can be computer controlled 54 Devices i E 6 Ag yal Ya pa E Combine Combine e Intellegence Human Input Algorithms Systems More E 2 Sensors Control Automaton System Figure 5 1 API design structure 59 or programmed A Device has a way of communicating to the physical device a set of parameters a set of sensors and a set of actuators It is not necessary for a device to have both sensors and actuators An example of a device would be the Nomadic Scout robot which can be communicated to via serial port has a variety of sensors and a motor control system Likewise a simple compass can be considered a device since it has a communication serial port and provides heading sensor information 28 Communication is any way of getting input to or output from a device This can be serial RS232 USB RS422 etc Ethernet radio or any other way of sending and receiving data from a device For example a microcontroller can be programmed using an RS232 connection and a Web camera s image can be obtained from the Internet using the HTTP protocol Communication is not limited to the physical but can also tie into operations of the host machine Files can be considered a form of communication since they can be written to and read from Parameters of a device include any feature that rarely changes over the operation of the device The serial port to which the device is connec
54. ented the back tracking behavior The reason for the wider turn is because of the needing to move forward to get out of the snow banks the downside being that the turning radius had increased Figure shows navigation moving between two points first moving to a start point up to the top point and then back down The turning radius effect is quite visible but the vehicle still managed to get near both waypoints despite having to turn 180 degrees to get back to the first MARVIN s turning was further tested in Figures and These show that MARVIN is able to make sharp turns in the snow to get to the desired locations Next MARVIN s long distance abilities were tested by driving far away Figure shows MARVIN driving to a start location and then 1 kilometer to the north and then taking a side path back 100 meters over and with two waypoints 500 meters apart Again in Figure 7 17 MARVIN goes out about one kilometer The path in Figure 7 18 shows the vehicle driving about 400 meters to target at this point the SAR antenna was orientated the wrong direction and the vehicle was driven the rest of the path Figure shows MARVIN driving over two kilometers to the point where SAR data would be collected And finally in Figure a full test involves the vehicle navigating a kilometer and then starting SAR movement the SAR pattern can be seen in Figure Overall the navigation was on average able to get to the waypoints with 3 25 meters with a standard deviation of
55. er the multiple and comes back a distance that is one width away from the starting point Let r be the turning radius w be the width 83 Width Figure 5 14 S curve movement pattern 84 State Calculation Next State Initial Pe Po Py Py P P 1 P P P P w P Ps P Peal Py Pa Pe P ww Py P Current waypoint l Po Py length wW P Pe width Table 5 1 S curve state transition calculations vector between defining point two and defining point three m is the multiple m 2r w 1 be the length vector between defining point one and defining point two P be the starting point then P P 1 P3 w m 2 Py Ps 1 Ps P w m 1 which through substitution P P w which is what is needed Doing this causes the pattern to double back on itself without causing the return to not be possible Figure shows a visual of the spiral pattern Table 5 2 shows the state transition calculation for spiral pattern movement 5 2 5 6 Sensor Fusion Sensor fusion occurs when two or more sensors provide similar data but possibly in different ways Sensor fusion is used to reduce error or to determine which value to use It is known that a position sensor can provide heading by calculating the angle between the points However when a vehicle using this as heading it could provide bad results as the vehicle heading can be shifted especially when the position
56. ering At times the vehicle may need to carry a human operator as well The platform must also be capable of towing a large 2m by 4m antenna array that weighs up to 150kg The radar antenna Requirement Value Towing Capacity 150kg Payload Capacity 200kg Rack Mount Space AO Turning Radius om Altitude 0 3000m Temperature 30 40C Range 60km day Table 2 1 Vehicle requirements brings into play the turning radius of the vehicle With too large a radius it becomes harder to position the antenna or to avoid some obstacles Too small a radius introduces the possibility of running over the antenna but could possibly be corrected through software The last set of factors comes from time and budgetary constraints The cost of the base platform involves more than just the sticker price of the vehicle but additional costs to making the platform working in the range of temperatures A more complex base platform will cost more to maintain fix and actuate than a relatively simple base Time is also a factor given that the rover had to be on the ice in less than a year from the time received Time constraints make the ease of platform conversion into a rover a higher factor A list of formal parameters can be found in Table 2 2 Platform Types There are many potential types of mobile platforms to consider This thesis examines snowmobiles ATVs Amphibious ATVs and RC Tanks as well as cus
57. ersity of Kansas Aug 2004 45 Sun Microsystems Java media framework api jmf 2004 Online Available http java sun com products java media mf 46 Tokyo Institude of Technology Buggy robots for operation on unstructured terrain gryphon 2003 Online Available http www robot mes titech ac jp robot wheeled gryphon gryphon e html 47 Topcon Legacy e gps receiver 2004 Online Available http www topcongps com hardware legacy e html 48 A Trebi Ollennu and J M Dolan An autonomous ground vehicle for distributed surveillance Cyberscout The Robotics Institute Tech Rep Apr 1999 49 Truck and Sport Outfitters Sportech mighty mini rear suspension wheel kit for 120cc snowmobiles 2003 Online Available http www truckandsport com content pages SPORTECH INC MIGHTY MINI REAR SUSPENSION product html 50 United States Department of Defence Unmanned ground vehicle master plan Oct 1996 51 Joint Architecture for Unmanned Systems Spt 2002 52 U S Census Bureau The geographic information systems faq 2001 Online Available http www census gov geo www faq index html 53 A Vicino and et al Development of an autonomous rover for exploration and scientific investigation in antarctica 1999 see project webpage Online Available http www dii ing unisi it control research Antartide Antartide99 htm
58. f data can be difficult to parse but information can be gained by creating a hierarchy of sensors that all stem from Sensor This gives more information as to the nature of the sensor and a quicker access to just what is needed rather than asking for all of information only part need be asked for In code a sensor is an interface it provides a way of accessing all of the data but is not the actual method of getting and storing the data There are simple versions of the sensor that provide an easy way to implement a sensor as well as provide a way to simulate sensor data 5 2 2 1 Position For a robot knowing the position is key to being able to navigate properly and give decent feedback about the relation of the other sensors to the world The Position Sensor covers this aspect by providing data in the form of a Point2D object The Point2D object is part of the Java standard and provides two dimensions x and y It can be used to represent any type of two dimensional position whether it is a dead reckoning system or latitude and longitude of a GPS Global Positioning System As a sensor the number of dimensions is two and the values are the x and y coordinates of where the position sensor thinks that it is It can be useful 97 indoors or where GPS is not available Figure shows a screen shot of the display used to show position data Figure 5 2 Position display 5 2 2 2 GPS Position is useful for ground vehicles but l
59. f when a switch is activated It is similar to a distance sensor except that it takes measurements in terms of a boolean registering true when the sensor is activated An array of these is placed around a robot like a skirt to alert it if it has run into an object Bump sensors are reliable because of their simplicity but by the time a bump sensor activates it may already be too late to do anything other than stop 5 2 2 8 Image Images while not part of the class hierarchy are an integral part of Java Java has an extensive library for dealing with images and video The Image class in Java allows for loading an image from a file or from the web The Java Advanced Imaging JAI adds and array image processing functions and expands the types of images that can be used Finally the Java Media Foundations JMF allows for loading of video from files streaming video of various types and the ability to grab data from a video capture card in a computer After getting the images and video image processing and vision systems can be build on top of the stream of images Images can also be used in displays to show more information 45 5 2 2 9 Other Sensors Other types of sensors can be represented using just the data field in the Sensor class In the API there exists a Weather Sensor which gets humidity barometric pressure wind speed and wind direction There is also a Level Sensor that measure volumes of liquids useful for keeping track of
60. fic angle where a wheel moves at a specific rate 3 Linear motors provide the ability to move in a line also called prismatic motors This motion can be achieved by a wheel motor through mechanical means worm gears pulleys etc The distinction is that a linear motor is moving to a specific point on a line A linear motor could be an elevator a throttle control motor or a hydraulic motor A motor limiter controls the possible values to a motor Limiters are a pure software motor that pass values onto the real motor but have bounds checks to control certain aspects of motors keeping them within safe limits For instance the throttle motor of the rover has much greater range than the throttle cable itself to hedge against mechanical problems the motor is limited to only move 69 to the values that make sense for throttling the engine All others are changed to either the high or low values This can be useful to prevent learning algorithms from being too aggressive on the equipment 5 2 4 2 Switches A switch controls values that are not controlled by a motor like a light switch or voltage level A switch still has an affect on the world but is not the motion that a motor has Switches are most useful for controlling circuits and aspects that are not physically moved However they could be used to indirectly control motors like setting the current to a motor causes it to move This would cause a loss of information
61. fing material The automotive material squishes 108 Figure 6 14 Frame side view measurements in inches 109 Figure 6 15 Frame top view 110 54 43 Figure 6 16 Frame bottom view measurements in inches 111 25 1 2 B S 8 Figure 6 17 Frame rack front measurements in inches 25 1 2 Figure 6 18 Frame rack back measurements in inches 112 OF Figure 6 19 Frame back view measurements in inches when the door closes to cover all of the gaps Around the door themselves a 10 cm strip of rubber is placed to help keep out even more water and to help seal when doors close Around the exhaust J B weld compound was used to seal off the metal parts Unfortunately not everything can be sealed air tight as the engine and the generator still need to get oxygen Air filters on the air in takes do the job of blocking the snow but letting air in Air filtering slides into groves made from angle iron attached near the existing engine vents 6 4 Finished Product Figure shows all of the components assembled to on and in MARVIN 113 Figure 6 20 MARVIN fully assembled for the Greenland 2004 field season 114 6 5 Software Control Systems A Nomadic Scout robot named Bob was used to help test the software control system Despite having almost completely different hardware Bob and MARVIN share almost identical control software The software from the sensors up controls how Bob and MARVIN com
62. gas in a fuel tank of a robot A Force Sensor to measure the pressure applied to an object a Current Sensor and an Inertia Sensor are ready as interfaces to be used 65 5 2 3 Extension to Sensor The sensor interfaces alone are quite useful but a few other pieces of code make them easier to use 5 2 3 1 Simple Sensor For each of the sensors including the base Sensor interface there exists an implemented version called a Simple Sensor Simple Sensor sets up much of the information needed by the sensor it represents It creates common internal variables event managers and sets up the data matrix and names Also provided is function that sets values of the sensor which propagate events to the listeners Using the setting functions of a Simple Sensor makes it possible to perform simulations on how a system will react to control values The set function also make a great way to play back data collected in a log file Simple Sensor internals can all be overwritten or ignored altogether Some sensors extend the Simple Sensor to remove most of the overhead whereas some sensors must use the specific interface 5 2 3 2 Logging and Logs as Sensors Logging is an important aspect of sensors There is a need to collect data process it and learn from it The logging system has the ability to log the event or to log periodically Both types of logging write to a stream which allows for multiple sensors to log to the same file if necessar
63. gation in Kansas moving to a known location 138 7 8 Waypoint navigation in Kansas full 180 degree turn test then followed by a driving to a base location 139 7 9 Waypoint navigation in Kansas first SAR test using 30m by 15m grid Unfortunately orientation aimed the S curve into the trees ending the test prematurely 140 7 10 Waypoint navigation in Kansas driving to a known location 141 7 11 Waypoint navigation in Kansas 20m by 20m SAR S curve navigation 142 7 12 Waypoint navigation in Greenland loop occurred because of a too high of a threshold MARVIN circled the target to try to get close 143 71 13 Waypoint navigation in Greenland MARVIN moves to the bottom point then to the top and back to the bottom 144 Waypoint navigation in Greenland MARVIN performing a full 180 to get the AR 145 7 15 Waypoint navigation in Greenland MARVIN performing a full 180 to get the target 146 7 16 Waypoint navigation in Greenland 1km drive out and two 500m Sci ee a a gee ae Bae goal Ge Wee ae 147 7 17 Waypoint navigation in Greenland 884 6 meter drive to a waypoint 148 XIV 7 18 Waypoint navigation in Greenland driving to a waypoint and then human drive to a slightly different location 149 7 19 Waypoint Navigation Greenland waypoint drives to perform SAR AE a EAN A 150 7 20 Wayp
64. guidance and a place to work Next I say thanks to Dr Chris Allen and Dr Costas Tsatsoulas for serving on my committee I also would like to recognize all of the faculty staff and students on the PRISM project for without them I would not have had the resources necessary for completing this thesis Particularly Dr Prasad Gogineni who headed the project my lab mates Rich Stansbury and Eric Akers who helped to build MARVIN and develop the API I thank my wife Jenifer whose support is greatly appreciated And finally I thank my family and friends This work was supported by the National Science Foundation grant OPP 0122520 the National Aeronautics and Space Administration grants NAG5 12659 and NAG5 12980 the Kansas Technology Enterprise Corporation and the University of Kansas ill CONTENTS Sd OF TABLES 2 263422 ses eee ei ee oe LIST OF FIGURES o iia die Raw dod debian Rap Lee ee a gee ee ee ee ee ee ee E ee abe wo ees ee See eee NN a eS A Sk ee AR a ee A Be ee ee we Lo APPS e SL bbw eave eos eee amp eres be BR DSRS ES A BSE wes pig ek eo ke Bee Gren eet ere eee ica ee ee ee ee ee be ue ee or eee pane ow Bee Oe eek ee A a ir a oe ii 2 2 1 1 Vebicles 2 5 ey is A OS ER 2 2 1 2 Conversion KI res Ja a sure de 2 2 1 3 UGV Snowmobiles RA peed oe eee ee wee S BR Se ee 2 2 2 1 Vehicle 25 4 4 eee sea EE 2 2 2 2 NETO x ea Od HH ROG OS 2273 UGV AVS Lee e
65. he ability of future rovers in arctic environments 8 3 Limitations Soft slushy snow proved to be an unpredictable bane to the rover requiring a higher turning radius and a causing few minor issues MARVIN lacked a true multiagent backend to determine what waypoints were important The line accuracy and the distance to waypoint targets while high can be improved 159 8 4 Future Work In the future the vehicle needs to work better on various types of snow The weight can be reduced and increasing the ground clearance will help with bad snow conditions The control system allows anyone or any program control to any level An access control system if set in place could help to control the different types of access and possibly recognize when a human needs control of the vehicle instead of a controlling program The access control could be seen as adding a security system The system could in the future learn to self calibrate instead of requiring a human to calibrate some of the parameters In addition to calibrating parameters the rover could learn how to drive better and compensate for the drifts in control that result from mechanics and snow Also to improve the accurate placement of the antenna The design to expand to controlling an arm that keeps the antenna on the line regardless of how the rover moves 160 10 11 12 REFERENCES E Akers H Harmon and R Stansbury Real time java for kur
66. he field Whereas a rack mount system would have a more stable mount within the vehicle 45 4 Winterization Since the rover must operate in arctic environments steps must be taken to ensure the safety of the onboard equipment The body of the vehicle must be able to protect the equipment that is not designed for use in cold temperatures Additionally the engine must be modified to handle the cold weather and the altitude 4 1 Protective Shell A protective shell is needed to protect the SAR radar and any other equipment inside the vehicle The shell should be able to withstand winds of at least 60kph with blowing snow In addition to keeping out the snow and cold the shell should also be able to vent heat generated from the engine and computer equipment It must also be able to house a human operator comfortly without being so heavy that the vehicle would sink into the snow 4 1 1 Standard Additions The Buffalo MaxATV comes with a wind shield a roll bar and a protective cover The default covering does not cover the back area where the equipment will go nor does it provide much protection from severe weather especially if stored outdoors The manufacture s winter package does not lend itself well to modification either so other options must be considered 46 Figure 4 1 Scale carbon fiber shell 4 1 2 Carbon Fiber Carbon fiber is a plastic used in airplanes models and various other applications It is lightweight
67. hes multiple items and because of this it will periodically do rounds and check all of them and calls reset on those that are not working any more This requires only one thread to watch multiple items and does not wait for the devices to reset This proves useful for restarting virtual devices or resetting parts of the code to get them back to a known state 5 2 7 Event Handling Since the architecture allows for both polling and events handling the events is very important The first event handling calls all listeners waits until they all finish and then returns control to the device sending the event This idea worked until slower components like GUls were added that required more time than a device needed to update its values Instead events were changed to propagate to the event listeners in a separate thread If the thread gets behind it starts tossing out the new events While losing the events may be bad at least there is less corruption of the events from not dealing with device quickly enough In the future it might be a good idea to have listener with different scheduling needs register themselves as to how quickly they need the data instead of dropping events The GUIs slowness in handling the events became less problematic when they ran remotely as the remote client would drop events and the only thing listening remotely was the GUI 88 5 2 8 Remote Sensing and Control A perfect remote sensing and control system wou
68. ibility but should not hurt performance Throttle on the other hand requires a much finer resolution of control requiring a more accurate position feedback In either case it is clear that a microcontroller is needed to control the motors as well as feedback sensors The microcontroller will also need to communicate to an on board computer 3 4 1 Microcontroller Some motor manufacturers also make controllers for their motors This makes the task of wiring and writing software for the microcontroller a done task In either case of buying a controller motor set or a microcontroller software to control the system is still needed Likewise since this goal of the project is to expand to being fully autonomous the control hardware will need to take this into account 3 4 2 Computer To be fully autonomous the system requires much more computing power than a standard microcontroller can provide To handle the needed processing power a ruggedized computer will be used to control the motor controller as well as the sensors computer also provides all the necessary capabilities to complete the remote control requirement through 802 11bwireless connection Using a computer instead of an embedded system also provides the ability to switch out the computer in the field or make software correction directly to the machine The computer could be either a rack mount system or a laptop A laptop provides easy access and has uses other than those in t
69. ic ATV is also examined Typically ATVs have a top speed over 40 km h and a turning radius of about five meters 161 16 2 2 2 1 Vehicles The Yamaha Big Bear Figure is a good example of a utility ATV Utility ATVs are designed as workhorses They are meant to tow equipment and handle rough terrain Unlike sports models they use their horsepower for towing and traction instead of speed The Arctic Cat 500 BTX is another example of a utility ATV Figure 2 6 6 Figure 2 5 Yamaha Big Bear 11 Figure 2 6 Arctic Cat 500 BTX 12 The Gorilla an electric ATV reduces the need for fuel and oil and greatly reduces cost of maintenance Electric power allows for use of alternative power sources like solar and wind However conventional rechargeable batteries do not do well in cold temperatures the vehicle itself may have problems with the cold weather The Gorilla is shown in Figure T6 Figure 2 7 Gorilla Electric ATV 2 2 2 2 Winterization ATVS perform well in dusty and dessert terrain but unless modified they have problems dealing with the cold and ice The undercarriage of an ATV is exposed to blowing snow and ice Ice will eventually cause damage to gears wheels and other exposed parts The surface area from the tires can push the ATV into soft snow causing it to get stuck more often The undercarriage can be covered to protect the ATV and a snow conversion kit can convert the rear tires to treads 13 a
70. igure 7 16 Waypoint navigation in Greenland 1km drive out and two 500m drives back 147 X Le 517619 7825710857 8054860 351199784 Zoom In 8054 2856 84 NW N NE 80541665 84 a ns4ls6s 4 wW E 205436584 18 054 265 84 8 054065 84 Sw sS SE 4 m m e Zoom Out 4 a 4 a ot K lt lt lt 1 gt Il fl 1 gt gt gt gt Figure 7 17 Waypoint navigation in Greenland 884 6 meter drive to a waypoint 148 E CEE cM K Y 517677 01471461396 8054433 777303174 Zoom In NW NE 8 054 429 23 8 054 379 23 2 054 9 Ww E 205427923 18 054 229 23 8054179 sw Ss SE 79 23 Zoom Out 79 237 3 elha Ps Figure 7 18 Waypoint navigation in Greenland driving to a waypoint and then human drive to a slightly different location A 17 547 06 y 17 597 06 dar Op Y auzzer0 0 v 17 897 05 12 947 06 3 K Y 517570 25903091003 8053930 294914189 Zoom In 8 0541943 87 NW N NE 8 054 743 87 8 054643 87 wW E 205444387 8 0541343 87 8 054 143 87 sw Ss SE 8 054043 87 Si i r rn Zoom Out at a 4 4 z K lt
71. important when selecting motors for actuation of the vehicle To measure the forces required to move the throttle and brake levers a digital force meter Figure 3 2 is used to find the exact measurements The force meter has 0 445 N 0 1 lbf resolution and can be mounted to a secured location eliminating human error of pulling on the force meter In all cases distance was only measured by the furthest point back needed to engage a full brake 54 Figure 3 2 Force Five force measuring tool The measurements on the levers were done at three different locations The 36 first location the low point would hide any show of actuation at the base of the lever where the levers meet the skid steering transmission The point eliminates any rotational forces caused by lever motion The force needed at this location is greater than 448 N and therefore not used The middle point even with the seat in the rover is easy to attach motors by simply extending from the existing seat to the levers The force at this point is a reasonable 155 7 N The final point of measurement just below the throttle control is as high as possible without interfering with a human driver The high point while not much higher then the medium point reduces the force required to 111 2 N This location requires a platform to be built to hold the motors The higher the motors are mounted the more rotational forces come into play and must be adjusted for Figure show
72. ionPak II provide temperature reading but now the WS2000 weather station is added and provides the outside air temperature All of these can be uniformly displayed Figure B 6 5 2 2 6 Distance A distance sensor measures the distance in meters from itself to a nearby object Sonar would be an example of a distance sensor A distance sensor has two dimensions the distance and the angle to a target These sensors provide a way for a robot to find and avoid obstacles in front of it or to map a room Distance sensors are an array of distance values There are two implemented sensors A 16 sonar sensor array around a Nomadic Scout and a laser range finder which provides 360 values over a 180 degree field of vision Figure shows a sample of what position heading and the distance sensor look like in GUI form 27 62 Figure 5 6 Temperature sensor display 63 Y SE WI A jeje TOR S f SS MLZ AZZ UNA ANU N Wf be SS a aeaii 100 7 SW S SE Y _ B PERE V Figure 5 7 Distance sensor is the outline a small line from the center shows heading and the position is indicated by the coordinates 64 5 2 2 7 Bump A bump sensor goes of
73. is no need to rewrite code to control different cameras just their motors This also allows for using different pan and tilt mounts with different cameras and still having the same ability as a fully packaged PTZC Figure 5 9 shows how the motors and image come together to make a pan and tilt zoom camera To demonstrate how this works there are two different cameras a Sony EVI D30 and a Pelco Espirit connected to an Axis 2400 web camera box but both use the same pan and tilt zoom interface In fact they share many of the same types of functions such as relative pan tilt and absolute pan tilt as well as a simple move up move left type of functions 41 29 The Sony EVI D30 provides controls through a serial port and a Belkin USB VideoBus video capture device is used to get the video The EVI D30 uses a set of byte code to control the camera into performing actions Within the API there is a driver that wraps the different necessary byte codes into the servo motor and linear actuator class This is implemented by having the actuator wrappers communicate what they want to have happened through a serial port controller class The controlling class tacks on important things like message headers and checksums as well as checking the checksum dealing with bad packets and synchronizing the communications to and from the actuators To get the images from the camera Java Media Foundations JMF is used to grab the frames from the video capture devi
74. itefoot rubber track conversion systems 2003 Online Available http www litefootatv com html product_information htm NASA Rover technology antarctic meteorite robots 1997 Online Available http ranier hq nasa gov telerobotics_page FY97Plan Chap2e html 2003 Online Available http www mars pictures net roverdetail jpg Nation Marine Electronics Association Online Available http www nmea org 162 27 Nomadic Technologies Inc Nomadic scout user s manual 1999 Online 29 32 33 39 37 38 39 40 28 30 31 34 36 Available ttp nomadic sourceforge net production scout scout_user 1 3 pdf gt Nomadic scout user s manual 1999 Online Available ttp nomadic sourceforge net production scout scout_langman 1 3 pdf Pelco Pelco esprit product specification sheet 2004 Online Available tp www pelco com ProductSpecs 2307 PDF EB Precise Navigation Inc Image of tem2 50 orientation sensor 2004 Online Available http www pnicorp com images products 18_large TCM2 Electronic Sensor Module User s Guide Santa Rosa CA PNI Corporation 2004 no 1000281 Rainwise Inc Ws 2000 sensor assembly 2004 Online Available http www rainwise com ws2000 2000spec html Recreative Industries Inc Buffalo all terrain truck 2003 Online
75. its but vendors provide weatherproof shells 7 Figure 2 14 Agro Bigfoot 2 2 3 2 UGV Amphibious ATVs Funded by the Department of Defense the Gecko is an automated Argo Bigfoot designed for reconnaissance and surveillance The amphibious nature of the vehicle allows the Gecko to scout across creeks and rivers without the need to place human soldiers in harms way 50 The Predator converted from a Predator ATV performs semi autonomous farming Some of its goals are given to it by a human but for the most part the vehicle drives and navigates on its own through the fields spraying chemicals and 20 GECKO UGV Figure 2 15 21 planting seed The semi autonomous nature of the vehicle fits well with the plans for the PRISM project as scientists will want to tell the rover to go to certain positions and to get there safely Predator uses a system of cameras gyros and differential GPS to navigate and model airplane servo motors to steer 17 Figure 2 16 Autonomous Solutions s Predator 2 2 4 Remote Controlled Tanks A remote controlled tank provides a simple electric platform already complete with a way to control it The AAVP7A model is an amphibious model which will make weatherproofing easy The RC tanks are usually made to 1 8 scale which is a little too small for the kind of equipment and power needed for the PRISM project However a custom 1 4 or 1 2 scale model can be made to order The downside
76. ke end effectors arms or legs can be created by combining actuators and sensors and building up to full control What is lacking is a way of controlling who has access and to which level they have access to a given system This can be added later by using a security control system similar to what Java has built in already The overall idea is to have a hardware abstraction layer and then build upon that to create the higher level logic and to make each part as small as possible allowing the higher level to put the pieces back together This differs from other systems like JAUS and PINROB which try to do control above the hardware layer 5 2 6 Health Monitoring In addition to being able to control and get information from hardware an autonomous system needs a way to catch errors correct if possible and continue operation This is done through watch dogs and an interface to be able to monitored For a device to be monitorable it must be able to state whether 87 it is functioning properly and have the ability to reset while running The idea is that if a device is not running then it can be reset There are two types of watch dogs designed for different cases The simplest health monitor periodically checks on a device and if it is not alive it sends a reset and then will wait until it is running Waiting for the device to reset helps with certain devices that take a certain amount of time to reboot like a laptop Another watch dog watc
77. ks It allows the test platform code to work on the rover platform by only needing to 71 redefine the hardware layers For purposes of this thesis g is an application The next section is devoted to examples of systems and applications ranging from the simple position to heading to pan and tilt zoom cameras to waypoint navigation Actions as a function of the senses Let S be a set of input senses s through s and A be a set of actions then S ls S2 Sn A a dg dn 5 1 A f S Function that processes sense values Let S and S be a set of senses then S2 g 51 5 2 Actions after processing senses Let S be a set of sense and A be a set of actions then A f g S 5 3 Multiple sense processing functions as a set of senses Let A be a set of actions g through gn a set of sense processing functions S through S be sets of senses then A f g S1 U g2 S2 U U gn Sn 5 4 5 2 5 1 Pan and Tilt Zoom Camera There are many pan and tilt zoom cameras PTZC but they all have different proprietary software to control them Yet They all have the same function 72 pan tilt zoom and take images The PanTiltZoomCamera class threats all the cameras the same A PTZC is define as being a combination of a servo motor as pan a servo motor for tilt a linear switch for zoom and an image sensor for the actual camera part Since the motors themselves contain the stop information there
78. l 164 54 Wagner Instruments Force five multi capcity force gauge Operation manual 2004 Online Available http www wagnerinstruments com manuals fdvmanual pdf 55 Yamaha Motor Corporation 2004 big bear 400 4x4 specifiations 2003 56 2004 vk540 III specifications 2003 165
79. ld allow the user program to access every feature as though they were at the console To achieve this goal Java provides Remote Method Invocation RMI that serves as a way for Java objects to communicate with each other RMI is designed to be a client server model That is a service runs and provides access to Java Objects to the client program RMI requires that there be a name registry RMl registry for which a server program opens access to remote classes The clients then attach by looking up the proper name for the service The client server model works if there are no call back methods i e event listeners With call backs there needs to be an object to get the events from the object generating the event like a sensor For this to work the remote listener must also be exposed as remote objects This will require a peer to peer system In peer to peer systems both programs act as a server and client exposing certain pieces while accessing remote methods of the other peer RMI does not just allow any class to become a remote class it requires special interfaces that extends the Remote interface These interfaces are then used to create Stub and Skel classes that can be passed on to a remote client The stub and skel classes perform all the hidden work such as making the method calls and threading the action so not to freeze an application Furthermore the remote interface must have a class which actually does all of the work that needs to be
80. le Performance 244424604446 do wee 125 Lal Automation 24 224 44e dede se Las ma 125 MA Motor renr E ee ee So 125 LAA ntr l ro RS A e ie 125 7 3 2 3 GoBook Max Laptop o 222220204 126 7 3 3 WeatherProofing Luce LL a a 127 A Skelli oe go daue III 127 7 3 3 2 COME aa a 127 7 3 3 3 Weather Stripping 4 se 4e gs eee bu 127 7 3 3 4 Rubber Seals 4 4 4 dis sa pau fees 128 7 3 3 5 Quick Weld 5 oa sus es aaa durs 128 7 3 3 6 Engine Weather Kit 128 CERES AA AA 128 7 3 3 8 High Altitude Jets 129 7 3 3 9 Aer IRE 129 7 3 4 2003 Assessment 44 64 ame de 4 dirt as 129 viii 74 MARVIN 2004 Results o 129 7 4 1 Weather Proofing oo e e a Se EE SG 130 A ee IM 130 7 4 2 1 AnS Tests AAA A 130 T422 rend sse s eta a YR oe BA eS aa 131 7 4 2 3 Overall Accuracy us a ssh a 157 424 2004 Assessment ce ee a a 157 E cane E eee E E E E 159 AM 2 ek moer ana poea ee a gad m gi oit 159 8 2 _Contributi ns lt s e ss r e s sa res Bee eee ae od 159 8 3 L mitations 4 1 x ake ba aa a a AA 159 8 4 Future Work es ass pass pra a A eed 160 1x LIST OF TABLES 2 1 Vehicle requirements vs veranos stats e 6 2 2 Information on snowmobiles 29 2 3 Information on ATVs s ses sr creuser Ge ES 30 2 4 Information on amphibious ATVS 44 4 31 2 5 Information
81. lt lt 1 gt a Il 0 1 gt gt gt gt Figure 7 19 Waypoint Navigation Greenland waypoint drives to perform SAR movement 150 Jes x Y 520989 75501753204 8057375 730863547 Zoom In 1 058 175 89 NW N NE 0571675 89 8 057 425 89 Ww a E 805092589 8 056 675 89 8 056 175 89 sw Ss SE 8 055 925 89 E a 3 3 mf Zoom Out q a z Is lt lt lt 1 Il 0 1 gt gt gt gt Figure 7 20 Waypoint Navigation Greenland Waypoint drives 2km to SAR data collection point 151 SAR Movement The main goal of MARVIN is to be able to perform SAR movements on ice The SAR movement tests involved moving an antenna in either the S curve pattern or the spiral path depending on the spacing of the SAR lines On the ice the goal was to perform a 100m by 1m Grid pattern This would test how well the spiral version of SAR The first test of SAR on the ice was to do a 20m x 20m repeating the test from Kansas At the end of this test the GPS sputtered out and stopped giving values giving only 4 of the points as seen in Figure 7 21 The spiral grid was tested after coming back from a test point Figure 7 22 There is a spot where the vehicle has trouble turning as indicated by the bump in the pattern The pattern was give
82. m can be analyzed This proves useful when doing obstacle avoidance simply collect sensor data showing obstacles and play that back to a stopped vehicle and then check actuator movement for the proper behavior Knowing that the data came from the real world it reduces field work to calibrating the actuators properly Playback as a sensor also works to test communication issues without the need for a field robot to be active The playback logs need not be generated by a sensor but can be hand fed data 5 2 3 3 Remote Sensing By using a combination of Java s remote method invocation RMI and the interfaces above remote sensing becomes transparent It is possible to make a remote sensor look and act like a sensor directly on the machine but with transmission delays This includes both polling and event driven data Event driven being slightly more challenging because of the event callbacks 67 5 2 4 Actuation Now that the world can be sensed it needs to be acted on This is done through the actuator hierarchy Whereas sensors had a getData method all actuators have a setValue method which tells the actuator what to do One can also get the current value of an actuator This value depends on the actuator Some actuators are self sensing and can return the real world value like a sensor However many actuators have no idea of their real world value and merely return the target value Actuators have been divided into motors and switches
83. method for adding HeadingSensorListeners and a method for removing them The RemoteHeadingSensor interface extends the Remote and has a method for getting the heading value However instead of adding and removing heading sensors it adds and removes RemoteHeadingSensorListeners The RemoteHeadingSensorListener passes the same HeadingEvent as the Head ingSensorListener but also extends Remote The BasicRemoteHeadingSensor implements the RemoteHeadingSensor and HeadingSensorListener interfaces but requires a HeadingSensor for its constructor and adds itself as a listener to the HeadingSensor The BasicRemoteHeadingSensor requires a name to connect to the local RMI name server This is the server side On the client side a RemoteHeadingSensorBridge class implements HeadingSensor and RemoteHeadingSensorListener The RemoteHeadingSensorBridge requires two RMI names the name of the RemoteHeadingSensorBridge and a unique name of its own so that the BasicRemoteHeadingSensor can communicate to it Since the BasicRemoteHeadingSensor implements the HeadingSensor interface can then be used in any application that uses a HeadingSensor When the application 90 requests the heading from the BasicRemoteHeadingSensor the RemoteBridge calls the BasicRemoteHeadingSensor for the heading which in turn finally asks the real HeadingSensor the value Likewise in reverse when a HeadingSensor produces an event the event is sent to the BasicRemote which then passes i
84. ms including robotics can be expressed as a function of the sensors giving an output of what the actuator values should be To differentiate from the JAUS the software for this project is designed in a object oriented hierarchical fashion Like JAUS each component of the software is independent but can combine to create synergetic effects A navigation system could be developed by combining position heading and a way of moving The way of moving should be independent of the navigation system how the heading is gotten or how the position is obtained The position could come from using GPS Global Positioning System dead reckoning or some method combining the two for higher resolution Robotics also requires some level of real time operation Certain operations need to perform in a given amount of time called real time constraints These constraints exist for safety and are used in situations such as aircraft stability and operation of nuclear submarines For the rover the real time constraints can be relaxed given the operating environment flat polar ice regions with little to no human population However it is still critical to avoid obstacles and ensure the health of the rover while in these regions 93 The combination of real time constraints plus the object oriented nature of the software led to the development of the control software for the rover in Java Utilizing KURT Linux and using the RTJ Real Time Java it is possible for
85. n a turning radius of 10 meters With the spacing and thresholds the values are good enough to show the pattern but not quite good enough to drive on the snow in a straight line The final test shows what happens when the waypoints are collinear this gives the maximal error for being off the line as every turn is 180 degrees MARVIN was allowed to drive for an hour giving Figure as the result 152 nee lp ay Figure 7 21 SAR Greenland SAR movement using a 20x20 meter id 153 E AS i q 4 Zoom Out H Ik lt 1 gt Il fil 1 gt gt gt gt 617 597 95 917 602 95 917 612 95 7517 96 917 622 95 Figure 7 22 SAR Greenland SAR movement using a 50x1 meter grid 154 x Y 521040 73812493315 8057465 662642842 Zoom In 8 057 504 21057 4949 8057 474 181057 464 P 181057 454 4 18057 424 p lalns7 414 h 181057 394 B 181057 394 p 18057374 8 18057 364 P 18057 354 P MESE ES ele fan 521 048 93 521 078 93 521 048 93 521 098 93 52111893 521 128 93 52119893 52109893
86. nSensor and a separate application can look at the GPS as GPS no need to translate for the different applications 52 Currently there are only a couple of GPS sensor drivers coded for the system One parses the National Marine Electronics Association NMEA strings and another provides access to Topcon GPS receivers which provide higher accuracy than NMEA NMEA can be output by most GPS receivers so almost any receiver can be integrated into an application One such application is to display GPS position on top of a satellite map see Figure for a sample satellite map 261 14 5 2 2 3 Heading In addition to position it is useful to know which direction a robot is moving This helps with navigation and obstacle avoidance The heading sensor is one dimensional and provides one value in radians from North going clockwise This covers compasses and other devices that provide a direction like wind direction This only covers the yaw only It is separate because many applications only need information in the xy plane Likewise many devices only provide a heading Heading can be obtained in a variety of ways magnetic compass or a dead reckoning system can provide heading information Another method is using a PositionSensor by taking two points and calculating the angle of vector created by the two points Already the benefits of the hierarchy can be seen where direction can be gathered from a GPS device or another position sensing devic
87. nd equipment would stand up to the arctic weather without failing or getting 124 stuck Testing of remote joystick control was also done Waypoint was tested but more sensors and slightly better control was needed to make it work 7 3 1 Vehicle Performance The vehicle proved itself to be a worthy snow rover Turning was possible on both icy snow and powdery snow The low vehicle ground clearance proved only to cause problems when ice was hidden underneath powder The hidden ice occurs after a larger vehicle like a snowcat had made a deep track during the warmer part of the day These tracks could be seen and avoided in the future The battery proved to work after a jump start The engine faired well but took some time to warm up much like any engine in cold weather In the future the engine could be heated at night At the end of the trip MARVIN took a drop out of a C130 aircraft to lighten the load No significant damage was sustained from the drop of a few feet save a door popping off and being repaired consequently 7 3 2 Automation 7 3 2 1 Motor The Linmot motors worked significantly better in the cold than in the heat When the motors were left in the brake position they would overheat after about 2 hours at least at 100 F temperatures In the cold the brakes would hold indefinitely 7 3 2 2 Control A human could easily drive by turning off the Linmot actuators and using the controls as normal Initially this method p
88. nd the front tires to skis more or less converting an ATV into a snowmobile as seen in Figure Another possible conversion includes changing all four tires to treads Figure 201 23 Figure 2 8 SnoTraxx ATV conversion kit 2 2 2 3 UGV ATVs CyberScout is a project by Carnige Mellon University to convert a four wheeled ATV into a surveillance rover The designers created two vehicles Lewis and Clark to navigate around the campus Servomotors and hydraulics were used to control the throttle and steering Sensors included a total of five cameras and a Differential GPS Lewis can be seen in Figure 48 The Gryphon series of robots were built to do search and rescue by the Tokyo Institute of Technology Gryphon I shown in Figure 2 11 uses a 6 1 14 Figure 2 9 LiteFoot ATV track conversion 15 Figure 2 10 CMU s Lewis from the CyberScout project 16 KW generator and a 500 W alternator for power and was remote controlled not autonomous Gryphon II expands to allow for a human pilot requiring a special Hybrid Actuation System Finally a heavy version Gryphon III Figure P 12 was constructed to handle winching capabilities as well as more sensors and a field arm 46 new alternator Se timing belt R steer lefi ale f steering shaft N E crankshaft ne g entiomete gt pote tior etery PE RS z Aort steer right encoder front left brake front right brake
89. o water could get in In the field the silicone only came loose in areas of high stress around the doors Everywhere else the silicone held the water seal The silicone still holds in many areas of the vehicle 7 3 3 3 Weather Stripping The automotive weather stripping varied in effectiveness Some the stripping fell off while in other places it bonded exceedingly well as it would tear in half 127 before coming off The weather stripping worked well in the compressed areas where pressure had given a nice hold long enough for the back glue to bond 7 3 3 4 Rubber Seals Rubber with silicone in the gaps held up and prevented snow from getting in The rubber was only used on the metal sheet between the equipment and the engine The sheet slid in from the back and locked in place through a couple of bolts The rubber covered a two centimeter gap between the sheet and the vehicle chassis pushing against the chassis to form the seal The gap existed in the original vehicle 7 3 3 5 Quick Weld The quick weld was used to seal off the exhaust pipes of the generator and the engine tail pipe The quick weld did not bond to smooth metal Engine and generator vibrations eventually caused the quick weld to shatter and fall off In places with less vibration the quick weld held In place of the quick weld aluminum tape proved to hold better 7 3 3 6 Engine Weather Kit The engine weather kit caused more problems than it solved Ultima
90. oint Navigation Greenland Waypoint drives 2km to SAR data collection AI 151 o 153 7 22 SAR Greenland SAR movement using a 50x1 meter grid 154 aaa aa a 155 dE A te 156 1 Introduction This thesis presents the details for construction of an uninhabited ground vehicle UGV for arctic environments It answers the question of what platforms work in polar environments and what needs to be done to actuate and control such platform In order to perform waypoint navigation using sensor and actuators added to the platform 1 1 Motivation What is an uninhabited ground vehicle UGV UGV is any ground vehicle where a human driver is not in the vehicle UGVs cover all forms of control from teleoperation to fully autonomous vehicles UGVs have been used by industry and government for some time and have proven useful in tasks dangerous to humans such as land mine detection and space exploration The UGV for this thesis is constructed to handle arctic environments Not only are arctic environments difficult for humans to live in they are difficult to navigate in Constructing a roving vehicle will eliminate tasks that are currently done by sending people out into the arctic environment Such a vehicle will need to survive the weather in the arctic regions as well as protect the equipment that it carries This thesis will cover selection of a base platform actuation weather proofing and software control systems of the platform Base
91. oller give it a location to head to via the Point2D class and a speed at which to get there Beyond that the navigator is on its own The navigator is a very reactionary base system Human Navigator The human navigator class relies on a human to get to point B and to let listeners know it has arrived This class is useful for when humans and robots must work together as an integrated system Obstacle Free Navigator The obstacle free navigator is an autonomous navigator that takes the simplest approach to get to point B and does not have obstacle avoidance The navigator requires position information and heading information It gets to the target by turning until its heading is within a threshold angle and then moves forward It will continue to move forward until the heading exits the threshold range or it gets to within a threshold distance of the target location If the heading is not acceptable the navigator turns until the heading is back in the threshold range As soon as the navigator gets to within the target distance threshold it stops and sends an arrived event Obstacle Avoidance An obstacle avoidance navigator builds directly from the obstacle free navigator In fact it controls the obstacle free navigator by changing the target heading so that the navigator will point to move around the obstacles 81 see Figure 5 13 The obstacle avoider requires that it be able to detect obstacles at currently a Distance Sensor is used
92. olving four levels system subsystem node and component The levels represent the distance from the hardware with the component level sitting just above the actual hardware The node level covers redundancies and hides all of the hardware level details Subsystems represent an individual part that controls nodes Examples include any single uninhabited system or any operator system The system level can be seen as the planner that controls the subsystems to achieve a higher goal 51 The University of Florida created a system that could be moved from one platform to another without modification The architecture consists of a Mobility Control Unit MCU Path Planner PLN Position System POS Detection and 92 Mapping System DMS and a Primitive Driver PD The system formed the beginnings of the ideas behind JAUS Autonomous Solutions has a software system called Mobius Mobius is used to control a wide variety of vehicles It allows for viewing through cameras a waypoint mode and a joystick controlled mode This software has been used to control military surveillance vehicles agriculture equipment and even an RC car Mobius is also compatible with JAUS 17 In industrial robotics an API call PINROB Portable api for INdustrial ROBots also seeks to unify robotics but on a much more focused level PINROB has fewer levels and is concentrated on robot manipulators like those used in a factory Ultimately all control syste
93. on tanks and robots lt a 4 4 uns sh au eu ae 32 3 1 Linmot inear actuators 42 3 2 Linmot inear actuators 24 DR D AU Ladder oe we eR es 43 3 3 Danaher linear actuators Los rousse wo te a Re ee SS 44 5 1 S curve state transition calculations 85 5 2 Spiral state transition calculations 86 7 1 Raw waypoint data eed ga ee ee a eek ke eo REE oe BS 158 LIST OF FIGURES 2 1 Arctic Cat F5 performance snowmobile 8 2 2 Arctic Cat Bearcat Widetrack touring snowmobile 8 2 3 Ski to wheel conversion kit for snowmobiles 9 2 4 Vision of robotic snowmobile systeM 10 25 Yamaha Big Beal ota a aaa a ee a 11 26 Arche Cat 500 BUM 4 ac 44440 444 Lu 44 Lau ERE EERO YS 12 2 7 Gorilla Electric ATV os ee ak be DANS e ee we Ra es Era 13 28 Sno Iraxx ATV conversi n Mb 24 sas a diia a wd ee dee d 14 2 9 LiteFoot ATV track conversion 15 2 10 CMU s Lewis from the CyberScout project 16 2 11 Gryphon I internals lt p rd A A e A 17 2 12 Gryphon II with field arm cesos da da 4e 18 Leu be Tae mi T oe eri 19 2 14 Agro Bigfoot 2 2 cb eke ke a RS Be eee A A a 20 a dos Va Ye Be e o E e da e 21 2 16 Autonomous Solutions s Predator 22 2 17 AAVP7A Amphibious RC Tank 23 2 ie Wh od RS Tr ei hee rie pe 24 NA
94. ount box 101 Figure 6 8 Dimension drawing of the MotionPak II The gyro also provides temperature tilt and inertia sensors as well The temperature sensor maintains the health of the gyro The tilt sensor is not used as it had a large drift rate of 60 degrees per second for both roll and pitch at least while the engine and generator were running but the heading had a much smaller drift rate of 0 007 degrees per second The inertial values are also not used The Gyro when combined with the GPS and feedback from the whether MARVIN is turning or going forward provides much more accurate heading information than either alone Figure 6 8 shows a diagram of the MotionPak II IT 12 44 102 Figure 6 9 TCM2 multi sensor 6 2 3 TCM 2 A TCM2 provides a heading sensor in the form of a magnetic compass a tilt sensor from two level sensors and a temperature sensor The magnetic compass while 1t worked in Kansas proved not to provide a decent signal once in was embedded into MARVIN The temperature sensor gave an accurate reading of MARVIN s internal temperature 31 30 103 Figure 6 10 SICK LMS221 outdoor laser range finder 6 2 4 Sick Laser Range Finder A SICK laser range finder the LMS221 shown in Figure 6 10 provides centimeter data up to 80 meters away over 180 degrees with half degree resolution The Laser Range Finder provides a very accurate Distance Sensor providing 360 samples much better th
95. out power makes switching to a human driver just a flip of a switch The use of large power is a concern The largest available from Linmot requires a peak of 2A at 72V 150W which is a lot of power when multiplied by three motors A cutaway of the linear motor is shown in Figure pIj 38 Figure 3 4 Top left medium DC motor top right car window motor bottom AC washing machine motor 39 Microelectronics i Stator windings 2phases i Load fixing Position sensors A Slider with neodymium magnets Figure 3 5 Linmot eletromagnetic motor 40 3 3 2 Linear versus Angular The direction in which a motor puts its force is also important to consider Angular force motors provide the force in a circular or angular motion This motion is useful for the conversion because levers when pulled back move in an arc from the attachment point Angular motion can also be converted to linear motion by using a cable that pulls on a line similar to a winch Angular force would be better placed at the attachment point of the lever but this would also require a strong motor The best method in this application is to use a winch cable attachment to connect to the levers Linear motors apply forces in a linear motion This is typically done with a worm gearing system or with a cable and pulley system This motion provides a direct method of moving the lever The downside is that the lever s motion causes rotational forces which act agains
96. plete goals With the exception of a few parameters the control software works identically on both 6 5 1 Position2Heading Sensor The Position2Heading Sensor is a smart heading sensor that utilizes data from the GPS and the Gyro to gives better results for heading than GPS or Gyro Gyro Drifts and GPS is unreliable when turning 6 5 2 Movement2D A DifferentialDriveMovement2D is utilized to control the left and right motors of Bob MARVIN combines the three Linmot motor attached to left brake right brake and the throttle respectively Despite the fact that both vehicles have different methods of controlling their movement the movement controls in software are the same through Movement2D 22 6 5 3 Joystick Control Joystick control uses the Movement 2D and directly translates the joystick movements to the motors The joystick control differs in how each movement works mostly since skid steering cannot go into reverse The joystick control for skid steering MARVIN treats all y values less than zero as braking as well This is because the skid steering changes the minus values not the joystick Bob moves almost in the direction that the joystick points y controls velocity and x controls 115 turning Joystick control for MARVIN was tested indoor with the engine motor off before adjusting throttle and brake positions these were done in the field In both cases joystick control works quite well 6 5 4 Simple Navigator
97. respect to the Nomadic Scout s own dead reckoning could be tested 122 7 2 3 2 MotionPak II The MotionPak II was also tested to help find the thresholds between when moving forward to use the position as heading or when turning to use the gyro This could also be compared to the Nomadic Scout s own heading 7 2 4 Local Joystick Control Joystick control worked as intended with Bob Pressing forward resulted in Bob moving forward turning to the right and bob does likewise This test was done to ensure that Movement2D was working properly 7 2 5 Remote Joystick Control This test involved having a second laptop control Bob across the network It relied on remote code working properly for Movement2D Control across the network was slightly sluggish this sluggishness was never measured but was fairly insignificant since ideally the full system will be autonomous 7 2 6 Remote Sensing Bob s remote sensors including seeing the sonar values and location of the Nomadic Scout as it moved around the laboratory Also tested was using the Vaio s built in camera to get Bob s point of view These worked quite well without fail and when combined with the remote joystick code provided a way to move around and scout areas without the need for the human to move The camera images where not affected much by the network but likewise suffered from a small delay During periods of high traffic it was best to watch Bob instead of the video for
98. roved easiest to drive until the hand throttle cable broke from not being heated up properly Afterwards the joystick became a very convenient way to drive 125 Local Joystick Local joystick had been tested with the vehicle off in the drive bay to get it to what would look like human control That is moving forward would release the brakes and pull on the throttle turning left would pull on the left brake turning right on the right brake and stop pushed the throttle to idle and both brakes back for a complete stop When activated in the field this worked just a well as in the lab The full throttle was a bit weak and the brakes needed to be adjusted for maximum turning capability The Buffalo turns better with more throttle and hard braking Remote Joystick This test was already Bone on bob it worked just as smoothly The joystick controls were passed seamlessly across the wireless network without any problems The network had the same delay as on the Nomadic Scout The vehicle could stop safely in an emergency even with a small delay Waypoint Navigation On the first field test waypoint navigation was not fully tested The vehicle could not get proper heading at least not just using the GPS As the GPS turned the heading would move too far in either direction Likewise turning speed was still set a bit high Note waypoint was not planned to work in this field season 7 3 2 3 GoBook Max Laptop The laptop proved to not only su
99. rvive in the snow but had an outstanding battery life of three or more hours Other laptops lasted about 30 minutes without power The GoBook also did not break under the strain of running all of the sensors control code and GUIs With all systems online the max CPU was around 20 Without the GUIs the CPU usage drops to 5 10 126 7 3 3 WeatherProofing MARVIN arrived on the ice about two months before being activated During that time no snow had gotten inside The air filters had frozen but had prevented snow from getting into the vehicle After warming up snow only entered from the doors being opened 7 3 3 1 Shell During the winter in Kansas the vehicle was tested in snow The rough driving caused the frame to shake and caused parts of the frame to shake loose The shell underwent reinforcement through the use of triangle brackets in the corners After another shakedown the triangles held the shell together The sliding doors on the side proved to be more of a nuisance in the field limiting the ability to get into the vehicle to do even simple things like starting the generator One of the front doors would brake loose from the silicon and rubber seals The doors were redesigned before the next field season 7 3 3 2 Silicone The silicone effectively kept water and snow out Before leaving for the field the roof seal were tested with water to check for any holes that may have been missed Eventually all holes were sealed and n
100. s first SAR test using 30m by 15m grid Unfortunately orientation aimed the S curve into the trees ending the test prematurely 140 AS Z mero kb exer st ay Figure 7 10 Waypoint navigation in Kansas driving to a known location 141 Y 303524 16970198567 OS e lion miettes polea Figure 7 11 Waypoint navigation in Kansas 20m by 20m SAR S curve navigation 142 e BOF ia E Y 517571 9918390384 8053913 949556373 1H Un 44h 49 Zoom In 8 053986 34 8 0 6 34 NW NE 8 053966 34 8 053956 34 8 052 946 34 Fa Ww E 8053493634 9 0534926 34 i 8 053 916 34 EC 80531906 34 sw S SE 4 8 05 cs cs cs c o al ja ca a 3 3 q q a n e 4 m m Zoom Out 2 043876 34 4 a at a at a a at Is lt lt lt 1 gt Il O 1 gt gt gt gt Figure 7 12 Waypoint navigation in Greenland loop occurred because of a too high of a threshold MARVIN circled the target to try to get close 143 E CEE x Ve 517572 2358962283 8053917 0065231705 Zoom In 18 053 992 73 8 0 NW NE 2052197273 L 1 0531962 73 f 8 0 9 w E 05394273 18 053193273 8 0 9 ae to 2052191273 sw sS SE 73 foom
101. s the possible points of actuator attachment High Point Medium Point Seat Transmission Figure 3 3 Posible motor points The throttle cable required a force of 15N for full throttle and 10N for half throttle The maximum speed of the vehicle will most likely not be used 37 3 3 Motors Different types of motors require different methods of attaching the motors to the control system of the vehicle In this project the differences of mechanical versus electromagnetic and linear versus angular were studied 3 3 1 Mechanical vs Electromagnetic Mechanical motors by definition use electricity to drive gearing systems Figure 3 4 shows the various sizes and gearing that are available with mechanical motors This type of motor has been around for some time and provides a good amount of force The mechanical motors can be adjusted to give more force using gears pulleys or other methods Mechanical gears do have a downside given enough moisture and cold they will freeze lock up and break the gears or burn out The term electromagnetic motor refers to motors that do not use gears to achieve their motion They are prismatic motors using electromagnets to move an object with very little friction The biggest drawback to these motors is that they require significant power to work and hold their position Power failure causes the motors to no longer hold and the vehicle will come to a stop The lack of resistance with
102. start moving from and the second defines the direction it should move in Upon receiving a arrived event from the navigation the next point is calculated by adding the vector to the last point given Mathmatically Pn P 1 Po Pi Bistatic mode is more complicated as turning radius becomes a factor Ideally bistatic mode causes the rover to move in a S pattern However sometimes the distance between points is too small to have the rover successfully turn so a spiral pattern is used instead Bistaic motion requires three points the first being the starting location and the next two defining the length and width vectors of movement Figurel5 14 To calculate the waypoints for either the spiral or S movement patterns the Mobile Radar Navigator keeps track of the current state The states are to move from position one to position two position two to position three position three to position four then position four to position one In the last state transition position one is really the fifth position but for calculating the next point it starts the states over again Table 5 1 shows the state transition and math Spiral pattern movement is performed when the turn radius of a vehicle is larger than the length or width of the bistatic movement pattern The spiral pattern forces the next point to move to a multiple of the width or length that is greater than the turning radius The spiral first goes to a distance that two widths or lengths long
103. t linux Spt 2004 class final project E L Akers Modelling and simulation of a mobile robot for polar environments Master s thesis University of Kansas Oct 2003 Alcan Composites Generic facade cladding specifications utilizing alucobond material 2003 Online Available ttp www alucobondusa com docs aluspec pdf S Alexei Radio control tanks 2002 Online Available ttp www interdacom ru tanks aa e E Arcitic Cat Pantera 800 efi specifications 2003 Online Available ttp arctic cat com snowmobiles Arctic Cat 2004 btx 400 model specifications 2003 Argo Argo 2003 Online Available http www argoatv com A Modular Scalable Architecture For Unmanned Vehicles Association for Unmanned Vehicle Systems Iternational Jul 2000 gt aC DA Axis Communications Inc Axis 2400 video server datasheet 2004 Online Available ttp www axis com documentation datasheet 2400 ds2400_2401 pdf E J E Bares and D S Wettergreen Dante IT Technical description results and lessons learned International Journal of Robotics Research vol 18 pp 621 649 Jul 1999 BEI Systron Donner Bei motionpak II Multi axis inertial sensing system Concord 2001 Bei motionpak II Multi axis inertial sensing system outline drawing 2001 Online Available https secure12 appliedi net systron images mp2 out gif 161
104. t no too expensive at 17 000 dollars The turning radius of zero meters would also help in moving the radar into place The flat bed would serve as place to put all of the equipment needed to power and run the SAR and control systems Also purchased with the vehicle were the roll bar wench track kit windshield and weather cover The roll bar windshield and weather cover would not be utilized 93 as they did not provide necessary weather proofing 6 1 2 Power For power a 5000 watt Shindaiwa generator was used 38 This would provide enough power to cover any unknowns as well as having a life of 6 7 hours on a full tank which would keep the vehicle alive long enough for a good day s work The generator exhaust was vented out the top of the vehicle with a cap on the top to prevent snow from falling down the pipe Further a firewall made of insulating sheet was placed between the generator and equipment compartment as the generator produced too much heat 6 1 3 Actuators Linmot Motors As described before the buffalo requires 112 N of force on the steering lever in order to move into the full back position and 15N of force to move to the throttle to full open position The requirements dictated designs in terms of power failures and other fail safes needed for control of the vehicle For these reasons Linmot linear actuators were used Two high power motors where installed for the brakes and a weaker motor was used for th
105. t the linear motors producing extra stress and reducing their mean time to failure This can be overcome by adding a rotational joint to the motors so that they move with the rotational force instead of having it act against them 3 3 3 Comparison Tables 3 113 3 shows a list of motors evaluated by their ability to fulfill the discussed requirements 15 3 4 Motor Control In addition to having the proper strength of motor for the job controlling the motors is also important Eventually to achieve remote control the motor controls will have to be through communication to a networked computer They will also need position feedback For the brake levers the position sensors do not need to 41 Linmot www linmot com Part Name P01 23x80 P01 23x160 Part 30x90 24V 48V 70x210 24V 48V 72V Reseller URL Cost Min Units Unit Cost Power W 48 144 24 96 201 6 Weight kg 0 383 0 383 0 562 0 562 0 562 Speed cm s 190 340 130 300 400 Peak Force N 21 79 32 91 21 79 44 03 60 05 Limit Force N 13 78 20 90 12 89 24 90 35 14 Min Stroke mm 30 30 70 70 70 Max Stroke mm 90 90 210 210 210 Accuracy mm 0 1 0 1 0 1 0 1 0 1 Length cm 17 7 17 7 25 7 25 7 25 7 Width cm 4 4 4 4 4 Height cm 3 5 3 5 3 5 3 5 3 5 Duty Cycle 50 50 50 50 50 Table 3 1 Linmot inear actuators 42 Linmot
106. t to the RemoteBridge that it turn passes it to the application When passing the event its source is changed from the actual sensor to the one who is passing the event this prevents outside access across the network which tends to adversely affect RMI Figure 5 16 depicts how this looks to the application This can all be done as a client server model that is until there are more than one client with the same name all trying to get the name on the server RMl registry At that point only one client can get events from the server and this breaks down Instead each client runs its own RMI registry to which the RemoteBridge classes register themselves This would work quite well as future projects could involve robot co ordination in which case robots can be servers of their location to the other robots without the need for a central server single point of failure 5 3 Application With all of the component defined and ready to go it is time to actually put all of it to the test on real equipment and real robots The major focus for application is waypoint navigation and proper SAR movement It is assumed that if an autonomous rover can successfully get to a waypoint then SAR movement being just a set of waypoints is achievable For testing the software two robots and many computers are used The first robot is a Nomadic Scout named Bob The second robot is the field robot named MARVIN Both robots use almost entirely different hardwar
107. ted to is a parameter Likewise an IP address updates rates and filenames can be considered parameters of a device A sensor gathers data from the real world An actuator causes changes to the real world A device can have any number of sensors or actuators As sensors and actuators change the most they will be the focus of development 5 2 2 Abstract Sensor As previously stated a sensor gathers data from the real world This could be a sonar sensor a camera or even a push button All sensors gather data and therefore in code should represent that data In the highest level any sensor has a certain number of dimensions and each dimension of sensor has a number of 56 values For example an image would have two dimensions x and y and number of values per each dimension like the pixel values of the image Similarly a weather station would have many dimensions temperature wind speed direction etc each dimension having only one value All sensor data can be stored as a large array stored by dimension and value Each sensor also has a name identifier likewise each dimension is identified by its measurement The data can be updated by either time or events The data can be retrieved at anytime or an event can be sent using event listeners The event listeners interface using the SensorEventListener class and have a callback function to get the events from Doing both allows for either type of development Having a large array o
108. tely it simply did not fit in the Buffalo very well The kit s exhaust would also split into the vehicle and there was not room to make an exhaust hole for it The kit was removed and not used in the field The engine worked fine without it 7 3 3 7 Oil During the first field season non synthetic oil was used It was changed to synthetic for the next trip 128 7 3 3 8 High Altitude Jets The engine carburetor jets helped make the engine run properly The vehicle started up easily and ran without stalling The jets ran a little too rich and caused some buildup on the spark plugs The plugs were cleaned and reused 7 3 3 9 Air Filters The air filters were attached by simply taping them to the outside of the engine air intake holes The tape eventually just fell off taking the filters with it A new holding solution would need to be created Otherwise the air filters keep snow out by freezing up instead of letting the snow pass After warming up the filters would drain the water out and allow full air flow 7 3 4 2003 Assessment Overall everything ran smoothly For the most part tape and other quick fixes did not do well in the cold weather The doors got in the way of getting to equipment Between seasons the doors would be redone the air filters fixed the shell reinforced and most importantly the code would be integrated for full waypoint navigation 7 4 MARVIN 2004 Results Between seasons a number of improvemen
109. to create turning motion Combinations of forward velocities and side velocities cause the vehicle to move in different patterns No forward velocity with side velocity leads to sharp turns where forward velocity with some side velocity causes wider turns The Nomadic Scout uses this method to drive 78 Movement 2D Left Wheel AA Motor ff E Differential Nomad l TENE Scout res Right Wheel Motor Left Brake kid Max ATV Right Brake Steerin Throtite Steering Wheel EZ Steering j Automobile Brake h Drive Throttle Figure 5 12 Movement2D Differential drive skid steering Akerman control systems 79 and Skid Steering Skid steering is accomplished by applying a brake to either the left or right side of the vehicle throttle controls how quickly the vehicle turns and how fast the vehicle moves To control this type of system three linear motors are used one motor controls the left brake one controls the right brake and one controls the throttle The motion is done by applying forward motion to the throttle and then subtracting the side velocity from the right brake and adding to the left brake This causes the vehicle to turn in place or compensate for turning errors in the vehicle itself The Buffallo MAX ATV uses skid steering to move and has three Linmot linear actuators to control the movement Ackerman Using servo motor and two linear actuators Ackerman vehicles can be driven The forward
110. to ordering a custom model is that it will take significant time 22 before it arrives Since an RC tank at the scale needed has never been built the specifications are not known Without specifications is cannot be determined whether the RC tank will meet all of the given requirements 4 Figure 2 17 AAVP7A Amphibious RC Tank 2 2 5 Customized Vehicles Customized vehicle refers to starting from scratch and designing the UGV from the ground up A custom built vehicle provides the flexibility to build any vehicle necessary to complete the job However custom jobs require much more expertise and time to build and arguably are more expertise Custom jobs tend to provide the greatest successes as well as the greatest failures In building a UGV from scratch all of the design constraints must be taken into consideration and accommodated 23 2 2 5 1 Nomad Nomad is a robot built by CMU to find meteorites in Antarctica Nomad has a unique collapsible chassis that allows it to fold up to be shipped Nomad has already proven itself useful for the exploration of arctic environments Nomad was also tested in a desert environment demonstrating that robots can be built to handle a wide variety of weather Nomad being a tested and proven vehicle gives valuable information on what works and what does not work for robotics in arctic environments Nomad included a variety of sensors including GPS laser range finders and video cameras 3
111. tom platforms Specifications from the manufacturer of each base will be compared to the requirements Sometimes the standard model of the base platform does not meet all the basic needs but add ons or optional modifications to increase their capabilities are available These add ons usually change the type of environment the vehicle can operate in like changing the skis on a snowmobile to wheels 2 2 1 Snowmobiles Snowmobiles design specifically tailors them to handle ice and snow They cruise through snow and ice and are one of the main types of vehicles used at polar base camps The drawback to snowmobile it that they do not work well on dirt and grass Replacing the skis with wheels will correct this problem and allow snowmobiles to drive in the not so snow friendly Kansas In addition snowmobiles generate noise which can interfere with radar operations 2 2 1 1 Vehicles Snowmobiles are typically divided into two categories those designed for racing Figure and those that perform work Figure The racing snowmobiles have higher top speeds and better turning radius However the work snowmobiles have more room for equipment and supplies For building the UGV speed is not as great of a factor as having space for automation equipment but the turning radius about six meters is important for control and obstacle avoidance 351151156 2 2 1 2 Conversion Kit A conversion kit shown in Figure 2 3 can be used to convert a snowmobil
112. ts were made to the vehicle The throttle motor was replaced with a larger motor The brake motors were adjusted to push on the brakes when not braking to increase the power to the not braked track The doors were redesigned from sliding doors to hinged doors Parts of the frame began to slip out of place specially the rack mounts This slipping was caused from the sliding nature of the t slotted extrusions To remedy this problem long bolts were 129 driven through the main sections of the frame to solidify the construction The bolts were also lock tighted and counter sunk into the extrusions Rails were also added to hold in the air filters And the front doors were reinforced with small sheet metal pieces and bolts During field tests the structure stood up to some rough treatment The 20 HP engine was replaced with a 27 HP engine to increase the power of the vehicle 7 4 1 Weather Proofing The change in doors did not compromise the weather proofing and the rails held the air filters in place for the duration of the experiment New automotive tape was placed better and clamped on for 24 hours before being released This caused it to hold for the duration of the experiment 7 4 2 Waypoint Navigation Waypoint navigation was performed in Kansas and in Greenland The tests were done using a 10 degree heading threshold and a 3 meter distance threshold The measurements included the actual distance to the target and the maximum distanc
113. unately this test was done only once as the ship date to Greenland was moved up The idea was that if MARVIN could do waypoints than this was merely a test of the SAR Movement Planner to giving the Navigator the correct points to move to Like the waypoint test error is measure by distance to the waypoint and the distance from the line connecting the waypoints Table 7 1 shows the raw data and Figure show the S curve movement pattern The black lines indicate the path traveled the waypoints are shown as the black squares and the stopping point of the vehicle is shown as a grey dot 7 4 2 2 Greenland On the ice the vehicle software had to be modified slightly to prevent the vehicle from building snow banks and getting stuck The software was changed to move forward every so often while trying to turn Turning would cause the vehicle to push loose snow into piles eventually leading to the inability to turn and at worst 131 not being able to move at all After performing the software updates MARVIN ceased to get stuck in the snow and went on to do waypoint navigation and some SAR tests Waypoints Waypoint navigation included the SAR navigation points For testing MARVIN was given various sets of points outside the base camp to navigate to Figure shows MARVIN barely missing the target and then performing a circle around the target For this reason the waypoint threshold was increased from three meters to four meters The increase prev
114. will be required by the motors to perform their task This is the most important factor as too little force in the motors will lead to control issues that cannot be solved by software The motors must also be able to survive the cold weather and be water resistant As a safety requirement if there is to be failure in the system the vehicle should come to a sudden stop Also in the event of failure of a motor the vehicle should come to a stop This means the motors must be monitored and in the case of the throttle motor must disengage on failure This means that it the state of the motors should be known that is whether they are on and what position they are in From a control point of view some degree of position 34 Figure 3 1 Lever controls for skid steering driving for a MaxATV 35 resolution is necessary However current design requires only two positions for the lever motors braking and free The throttle motor on the other hand requires a higher level of resolution as speed control is more important Added to this requirement is the ability for a human override on the vehicle A human override provides the ability to complete the task in case of failure of the control system In arctic environments it may not be possible to replace parts but it is possible to assign a human the task of driving the vehicle 3 2 Measurements The first factor to selecting a motor is the amount of force needed Force measurements are highly
115. will be weighed to determine the viability of the vehicle to perform the job of being a mobile SAR Several platforms are judged on past experiences and ability to handle the harsh conditions The second phase involves converting the vehicle into a computer controlled UGV The tests done in this phase determine what needs to be done to automate and winterize the vehicle Winterization is tested by applying water to the seals placing equipment into an environmental chamber and finally in real arctic weather The control software is tested on how accurately the vehicle can approach a waypoint in the snow The final phase involves field testing the rover in a variety of conditions The vehicle is tested in Kansas to see how well everything stands up to warm weather and punishment at an ATV park The final test is to see how the UGV stands up to the environmental conditions on Greenland s ice sheet 1 4 Thesis Organization This thesis is organized into eight chapters Chapter 1 is the introduction Vehicle selection follows as chapter 2 Chapter 3 pertains to the steps taken to actuate the driving of the vehicle Chapter 4 examines the various methods of weather proofing vehicles Chapter 5 discusses the control software Chapter 6 presents the steps chosen and an overview of the construction of MARVIN The results and analysis of field tests are presented in chapter 7 And finally chapter 8 ends with the conclusions and future results 2 Mobile B
116. www linmot com Part Name 37x120 37x240 Part 20x100 24V 48V 72V 60x260 48V 72V Reseller URL Cost 1 300 Min Units 1 Unit Cost 1 300 Power W 72 144 432 144 360 Weight kg 1 200 1 200 1 200 2 214 2 214 Speed cm s 140 260 400 130 220 Peak Force N 60 93 60 93 121 87 120 09 204 16 Limit Force N 40 92 40 92 81 84 72 05 119 21 Min Stroke mm 20 20 20 60 60 Max Stroke mm 120 120 120 260 260 Accuracy mm 0 1 0 1 0 1 0 1 0 1 Length cm 22 7 22 7 22 1 34 7 34 7 Width cm 5 5 5 5 5 Height cm 5 5 5 5 5 Duty Cycle 50 50 50 50 50 Table 3 2 Linmot inear actuators 43 Danaher www danahermcg com Part Name Electrak 1 Electrak 2 E050 E150 Part SP1 D12 DE12 DF12 Reseller URL Cost Min Units Unit Cost Power W 67 2 240 45 6 156 Weight kg 0 659 4 873 2 477 Speed cm s 1 778 2 54 1 8288 5 08 Peak Force N 333 6 1112 266 88 2001 6 Limit Force N 333 6 1112 266 88 2001 6 Min Stroke mm 0 0 0 0 Max Stroke mm 152 4 203 2 152 4 152 4 Accuracy mm Length cm 16 36 27 3 31 8 Width cm 4 7 6 5 3 9 8 Height cm 7 3 14 7 10 3 19 4 Duty Cycle 25 25 25 25 Table 3 3 Danaher linear actuators 44 be more than a couple of switches to determine if the lever is in or out This may limit flex
117. y or to a distance server or anything else that can be connected by streams By default the stream is a time stamped file name and each item in the log file has a timestamp Time stamping the log file makes it easy to group runs of sensors together time stamping events allows for playback at the same speed in which the events occured All logging is done through two logging classes TimedDataLogger and 66 EventDataLogger The TimedDataLogger requires a time period and a method to call to get the data most likely the toString function built into every Java object the source does not have to be a sensor or a more formatted function to supply information The EventDataLogger works by turning itself into an event listener from the source and writes out the events as they are generated to a log file It can convert itself into the proper listener by knowing which listener interface to implement and what function receives the events to be logged After logging the data from the sensors events can then be played back as the type of sensor from which they originated For example if GPS data is logged from any source NMEA Topcon etc then the log file will look exactly like the GPS it logged This means that the GUIs for the sensor and the logs are the same and can be used to analyze the data Doing this also allows for isolating sensors and actuator behavior Logs can be used in place of other sensors and the behaviors of the rest of the syste

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