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Design, Implementation and Evaluation of a Self

1. Figure 2 8 MIB510CA interface board contain both MICA2 and MICA2DOT motes as they are compatible with each other 2 5 4 MIB510CA The MIB510CA 36 interface board allows for the aggregation of sensor network data on a com puter and provides an RS 232 serial programming interface As shown in figure 2 8 on page 17 it has connectors for MICAz MICA2 and MICA2DOT motes To program the motes an installa tion of TinyOS 30 is required instructions can be found in the getting started guide 35 The Windows operating systems also requires an installation of Cygwin 5 2 5 5 MULLE The MULLE is a small Embedded Internet System EIS platform which was developed at Lulea University of Technology It is based on a Mitsubishi M16C microprocessor and uses Bluetooth for wireless communication With low power consumption and a small physical size the MULLE is excellent for mobile applications Its small size 25 x 23 x 5 mm is visualised in figure 2 9 on page 18 The model used throughout this project utilizes a LM61 temperature sensor 24 to receive temperature information Other available sensors include accelerometers and light sensors The MULLE software platform consists of the following parts 2 Background 18 9V Battery MULLE Figure 2 9 The MULLE wireless sensor networking platform e lwIP 21 a small open source implementation of the TCP IP protocol suite focusing on reducing resource usage This makes lwIP suitable for
2. Appendix I Server The first step in creating the server is to set up a ServerSocket that clients can connect to the accept method blocks until a connection is made ServerSocket serverSocket new ServerSocket 8189 Socket incoming serverSocket accept After a client connects two object streams are associated with the socket allowing object to be sent between the client and the server ObjectOutputStream outStream new ObjectOutputStreanm incoming getOutputStream ObjectInputStream inStream new ObjectInputStream new BufferedInputStream incoming getInputStream Sending and receiving objects are accomplished via the read and write methods of their respec tive stream class outStream writeObject packet object inStream readObject The newly received object is then passed along to a handler which uses the Java operator instanceof to determine the type of the object Depending on the packet type different action are taken handler parse object If the object is a SteerPanelPacket the user wants to move the robot and has activated the steering panel in the GUL The relative X and Y movement can be found by calling its respective get method SteerPanelPacket packet SteerPanelPacket object int x packet getX int y packet getY If the object is an ImagePanelPacket the user uploaded specific locations that the robot should visit They are represented as three
3. Device Resource type representing a single physical device like an IR sensor a motor or a camera Device group Multiple devices handled as a single resource such as a drive system composed of several motors The HAL has a resource manager to handle allocation instantiation and activation of resources It is also responsible for deallocation and to free memory when the resource is not needed any more There are configuration files needed for the resource manager to be able to load resources correctly The resource description files are usually done in XML Evolution Robotics supplies predefined configuration files for both the Scorpion and the ER1 robot Behavior Execution Layer Short BEL is a framework for building autonomous robotic systems 14 The main part of the BEL is the behavior It is defined as a computational unit that maps a set of inputs to a set of out puts The inputs and outputs are conveniently named ports Ports are characterized by their data type data size and semantic type Output ports can have connections to an arbitrary number of input ports Behavior networks can be formed by chains of connection behaviors They are executed se quentially and at the same rate in a FIFO first in first out manner 2 Background 11 The implementation of behaviors and behavior networks can be done using either C objects and files or using XML Since it is easier and more standardized to use XML the ERSP provides an in
4. e int getConnectedPairs e void addLandMark int x int y void go The main method in this class is getConnectedPairs This method should be called when all waypoints and goals are added First thing that happens is that the current goal is added to the end of the waypointList int way new int 2 way 0 goal_x way l goal_y waypointList add WPCount way WPCount A loop will go through the whole waypointList and use the static Exploration class in stance eg and its method gotPath to examine if a path between the waypoints is possible If that is the case the size length between the waypoints is stored in the sizer integer array int sizer new int waypointList size for int count 0 count lt waypointList size count way waypointList get count boolean test ex gotPath start_x start_y way 0 way 1 if test true sizer count ex getSize else if way 0 goal_x amp amp way 1 goal_y System err println Can not get path from start to goal System err println Waypoint way 0 way 1 not possible Next the order of the waypoints needs to be set The waypoint that is closest to the start position should be moved to first The one closest to the second waypoint should be moved to next and so on until the goal is reached To achieve this a method named getMinIndex is used to get the index of which waypoint has the short
5. The MPR410 MICA2 motes have two separate tasks At first when connected to an interface board they function as a base station Secondly equipped with a sensor board they act as sensors transmitting data to the base station The battery powered MICA2 mote is based on the low power Atmel ATmega128L microcon troller which runs TinyOS TOS from its internal flash memory Equipped with two 1 5V AA batteries it has a lifetime that exceeds one year External power can be provided through the stan dard 51 pin expansion connector or the 2 pin Molex connector Indoors the tested range was on average 16 meters in a fairly open space The MPR410 mote is illustrated in figure 2 5 on page 16 2 5 2 MTS310CA The MTS310CA sensor board illustrated in figure 2 6 on page 16 is used to read the tempera ture at desirable locations It is equipped with a surface mounted Panasonic thermistor with a nominal mid scale reading at 25 degrees Celsius This sensor board is also equipped with a light sensor accelerometer magnetometer microphone and a sounder 2 5 3 MICA2DOT If physical size and low weight is important the robotic device can also communicate with the small quarter sized MICA2DOT 36 motes see figure 2 7 on page 17 However small size im plies deteriorated battery capacity and reduced functionality A wireless network installation can 2 Background 17 MICA2DOT MTS510 9V Battery Radio Module Sensor Board Figure 2 7 MICA2DOT motes
6. the MULLE would not have functioned 4 6 Enhancements for Mica 4 6 1 A programmable interface Mica has no programmable interface and this has resulted in a prototype that runs the enclosed program via system commands in order to obtain data A better solution would be to provide a library that could be used instead 4 7 Software prototype usage areas 4 7 1 Air condition controller As the goal for this project was to create a self controlled robotic device that moves to specific areas in order to read temperature sensors a possible usage area is an air condition controller Once a value is read from the sensor the robot assures that it is within the specified range If contrary to expectation the temperature should deviate from the normality counteractions will be taken to ameliorate the situation A mobile robotic device of this kind might be necessary when the sensors can not directly communicate with the base station This might be the case if the sensors are to far away or if there is distortion in the network The created prototype can move to numerous sensors and store information from them and deliver that information to the base station once it is in range 4 7 2 Surveillance The temperature sensor on the MULLE can be exchanged for a motion sensor an IR sensor or other types of sensors With motion sensors and IR sensors the robotic device could act as an analyst of the data received from these sensors If something suspicio
7. the importances of the improvements uncovered when the technology is combined are in our sense greater These improvements are often major and would result in extensive changes of the technology changes that often could give the advantage of more users and all of its positive side effects Conclusively it is important for a developer or a company to retain a good way of receiving feedback and make sure that the feedback is thoroughly analyzed 4 10 Evaluation 4 10 1 Educed software prototype What has been achieved is that a Scorpion or ER1 robot can move to waypoints and goals con sisting of x and y positions received by a GUI The shortest path to the goal is calculated and waypoints on this path will be used when navigating This means that waypoints that are not along the path will not be taken into consideration when navigating When the robot is at a start position there is no way of knowing the direction the robot is facing except for looking at the video stream that is sent to the GUI There is a possibility to move the robot by a steer panel so that it is facing in the direction of the upcoming waypoint Ekahau is used for getting the current position for the robot However Ekahau supplies no client for the Linux operating system so a PDA with the Ekahau client installed needs to be placed on the robot Due to the inaccuracy of Ekahau a start position must for now be set by hand With Ekahau logical areas can be created a
8. about the client s functionality can be found in Appendix J Chapter 4 Discussion This chapter discusses the problems that occured and investigates the stipulated areas indepen dently revealing weaknesses and possible improvements A couple of considerable usage areas will be stated and the questions asked in the introduction will be answered The software proto type is then evaluated 4 1 Problems These are the major problems that occurred throughout the project Several minor problems that appeared will not be mentioned since a solution surfaced almost instantly 4 1 1 Scorpion robot A major decisive issue with the Scorpion robot was the mechanical problem that occurred with the drive system The robot could not move forward or turn left but move backward and turn right After a week of efforts trying to make it work the Scorpion was discarded and the ER1 robot became the primary robotic device To make the ER1 work with the ERSP different software modules were needed Some of the modules supplied with the ERSP were not working and new modules had to be downloaded The drive system for the ER1 is however not moving the robot accurately If the robot is sup posed to move along a straight line it will almost always make a small turn A longer movement will then result in a more deviant final position Furthermore the ER1 is not fully compatible with the ERSP API Some methods are not working as stated in the API 4 1 2 E
9. an extension to the C programming language primarily designed for embedded systems Both TinyOS and nesC was developed by a consortium led by the University of California Berkeley 2 6 4 Cygwin The free software Cygwin is a porting of GNU is not UNIX GNU for Microsoft Windows Cyg win creates a UNIX like environment with many of its standard utilities including development tools such as GCC and GDB Programs can make use of both Microsoft Windows API and the 2 Background 20 Cygwin API This facilitates porting of other UNIX programs without radical changes to the source code Cygwin is developed by Cygnus Solutions and supports all modern 32 bit versions of Win dows with the exception of Windows CE However Cygwin can not do more than the underly ing operating system supports and will thereby sustain different limitations depending on which version of Windows is used 2 6 5 M 16 Flasher The M16C Flasher is a Graphical User Interface GUI for programming Renesas M16C micro controllers In order to flash the microcontroller it must be connected to a PC via a serial cable However be cautious about the different voltages of the COM port and the microcontroller The standard PC COM port delivers 12VDC while the microcontroller expects 5VDC and 0VDC M16C Flasher supports Microsoft Windows 95 98 ME 2000 XP operating systems and is free for non commercial use 2 7 Hardware and software requirements Besides all previously ment
10. different ArrayLists that contains points and can be re ceived via their get functions Scanning through the ArrayLists in this case just to display the coordinates on the standard output is easily done by the new for loops introduced in Java 1 5 ImagePanelPacket packet ImagePanelPacket object ArrayList lt Point gt waypoints packet getWaypoints ArrayList lt Point gt landmarks packet getLandmarks ArrayList lt Point gt goals packet getGoals j for Point p waypoints System out println p getX p getY In case an EkahauPacket is received the logical area visited by the robot has to be determined before taking appropriate actions EkahauPacket packet EkahauPacket object String logicalArea packet getLogicalArea If the robot is near one of the mica motes that is inside the logical area surrounding either the printer or the corridor their respective temperature are updated by calling the appropriate getTemperature method provided by the moteHandler class if logicalArea equalsIgnoreCase printer temperature PRINTER moteHandler getPrinterTemp if logicalArea equalsIgnoreCase corridor temperature CORRIDOR moteHandler getCorridorTemp Should the robot be in the vicinity of the Bluetooth MULLE which is located in the meeting area some additional rows of codes are required This is due to that it is impossible to dire
11. e To integrate areas and educe a software prototype to obtain depicted goal e To enhance experience and understanding of the Java programming language e To improve software documentation skills e To reveal independent weaknesses and improvements for the stipulated areas e To appraise the educed software prototype e To ruminate the results and ascertain improvements Furthermore two important questions will be answered e Is there a need for current software applications and its developers to think more about compatibility e Will the method of combining technologies uncover improvement information more con cisely than looking at a single technology independently 1 Introduction 7 1 3 Delimitations The disposable hardware and software will limit the thesis from becoming too comprehensive However the educed software prototype will as far as possible be designed to allow extensions of other areas or technologies As a combination of this kind has never been conducted the support is limited and will influence the extent The focus of the thesis will be in combining technologies and for that reason there will be no harder attempt in making the code for the prototype either neat efficient or secure 1 4 Outline The thesis is outlined in the following manner Chapter 2 gives background details about the Scorpion robot ER1 robot Evolution Robotics Software Platform Ekahau Mica sensors and the Bluetooth MULLE It also brief
12. embedded systems with scarce mem ory and processor resources e lwBT 19 implements the upper layers of the Bluetooth protocol suite designed to trans port data from lwIP over Bluetooth Similar to lwIP lwBT was developed for small embed ded systems with scarce resources e Network Address Translation NAT 29 A small open source implementation of NAT for lwIP enabled devices NAT is used to create an ad hoc network which shares a single connection to an external network e Web and sensor server The MULLE is capable of sending data via external networks since it uses standardized Bluetooth and TCP IP protocols This requires either a Bluetooth LAN access point or other Bluetooth enabled devices with appropriate software installed 2 6 Languages and software 2 6 1 Java Native Interface The Java Native Interface JNI provides a way for Java applications to incorporate native code written in programming languages C or C This can be done in two ways using either native libraries or native applications With native libraries native methods are written within the Java application and for native applications a Java Virtual Machine will be embedded into a native application Since Java will be the programming language used throughout this project native libraries will be utilised See Appendix A for details on how to write native libraries 2 6 2 Eclipse Eclipse 8 is an open source framework for delivering rich client ap
13. empty For RGB values of 0 the grid square will be set as full Other RGB values will set the grid square as unknown AnExplorationGrid object will be created based on the OccupancyGrid object 3 Method 25 The Java implementation of the path planning consists of two classes Exploration java and FindPath java In Exploration java there is a native method doExplore that takes start and goal position as arguments and is used to find the shortest path In this native method another method from the ExplorationGrid class is used to get the shortest path be tween the points An integer array of the path is returned by the doExplore method Since the method for finding the shortest path gives coordinates as close as possible to sta tionary objects like walls in order to reduce the path length it is necessary to ensure that the robot moves via specific waypoints in order to reach a goal If not an excessive amount of obstacle avoidance is needed and will result in gratuitous program execution The FindPath class contains methods to retrieve waypoints in any order connect them together and use the Exploration to find the path to go A more detailed description of how the most important parts of the Exploration and FindPath classes works can be found in Appendix C For the robot to move around and avoid moveable objects that can occur some form of ob stacle avoidance is needed 3 1 8 Obstacle avoid
14. goal_y amp path shortest path is found the success variable will be true and the path will be in the path list Since JNI does not have any good way of returning specific objects the path list will be converted to an integer array by looping through the list obtaining the positions and setting them The start position will be set in static variables in the Exploration class i f success ine otic EN Wall jclass intArrayClass env gt FindClass 1 if intArrayClass NULL return NULL jArray env gt NewIntArray path size x 2 if jArray NULL return NULL for GridPointList iterator i path begin i path end i if first true env gt SetIntField jobJ startxID i gt x env gt SetIntField jobj startyID i gt y first false else buf 0 i gt x env gt SetiIntArrayRegion jArray y 1 buf tty buf 0 i gt y env gt SetIntArrayRegion jArray y 1 buf y else cerr lt lt Could not generate a path from start to goal lt return NULL return jArray When the integer array is returned it is used by the nextMove method in the 1 lt endl Exploration class This method will make the robot move and the process in doing so starts out with turning the integer array into separated arrays for the x and y coordinates In order for the robot to move as long as possible without turning a while loop is used to find out
15. how many pixels the robot will move in the same direction This is done for the whole integer array The x and y variables will be multiplied with the number of pixels the robot can move in the same direction for i 0 j 0 i lt intArray length 2 1 i j Xcords i intArray j Ycords i intArray j i 0 x Xcords i startX y Ycords i startY 1 5 count 1 xfirst x yfirst y while i lt size 2 1 while i lt size 2 amp amp Xcords i Xcords i 1 xfirst Ycords i Ycords i 1 yfirst f count 1 itt x xfirst x count yfirst count K ll amp Then the coordinates needs to be switched since x coordinates on the map represents y coordi nates for the robot and vice versa There is also a check to see if we need to turn before we move The x and y variables are multiplied by the length of a pixel in this case 8 5 centimetres These values should be set from the GUI or somewhere else When this is done the static Move instance is used and the method setNextWP x y is called tmp y y Xx if tmp lt 0 x tmp else x tmp x gt 0 amp amp ylast lt 0 move setAngle 90 i else if x lt 0 amp amp ylast lt 0 move setAngle 90 x x 8 5 y 8 5 move setNextWP x y ylast y The movement must be finished before new coordinates can be set otherwise they will be skipped
16. invalu able 37 Bibliography 1 Advanced packing tool description http en wikipedia org wiki Advanced_Packaging_Tool Address valid as of April 26 2006 2 Frank M Carrano and Janet J Prichard Data Abstraction and Problem Solving in Java Addison Wesley 1 edition 2001 3 Gary Cornell Cay S Horstmann Core Java 2 volume Volume 1 Fundamentals Sun Mi crosystems Press 7 edition 2005 4 Gary Cornell Cay S Horstmann Core Java 2 volume Volume 2 Advanced Features Sun Microsystems Press 7 edition 2005 5 Cygwin homepage http www cygwin com Address valid as of April 4 2006 6 Bruce Eckel Thinking in C Prentice Hall 1995 7 Bruce Eckel Thinking in Java Prentice Hall 3 edition 2003 8 Eclipse homepage http www eclipse org Address valid as of April 17 2006 9 Ekahau homepage http www ekahau com Address valid as of April 4 2006 10 Ekahau developer guide Not available for public access 11 Ekahau user guide Not available for public access 12 Evolution robotics software platform api Not available for public access 13 Ersp scorpion manual Not available for public access 14 Ersp user s guide Not available for public access 15 Evolution robotics homepage http www evolution com Address valid as of April 15 2006 16 Elliote Rusty Harold Java Network Programming O Reilly 3 edition 2004 17 Java sun homepage http java sun com Address valid as of Ap
17. is done via the Java Socket class Socket socket new Socket IP PORT Communication with the MULLE is handled by two data streams The output stream lets the application write data across the network whereas the input stream reads information sent from the MULLE DataOutputStream outStream new DataOutputStream socket getOutputStream DataInputStream inStream new DataInputStream new BufferedInputStream socket getInputStream Before the Bluetooth MULLE start transmitting readings from its temperature sensor it must receive a start command over the network connection outStream writeByte START Thereafter the data packets containing the 16 bit number from the ADC are received by reading two subsequent bytes from the input stream low inStream readByte high inStream readByte Changing the endianness necessitates some byte arithmetic s Firstly shift the bits of high 8 steps to the left the right hand side is then filled with 0 bits Secondly merge the high and low bytes together with the bitwise OR function Finally the recently merged bytes are passed through the bitwise AND function together with the hexadecimal number 0x00000FFF reading low high lt lt 8 amp 0x00000FFF Table X and X explains the result of using bitwise OR and bitwise AND functions respectively whereas table X illustrates how the decimal numbers 0 to 15 is represented in hexadecimal and binary form FIXME Tables
18. make sure that an optimum temperature is maintained in all areas of for example an office the robotic device moves to predefined locations and receives the current temperature from a wireless sensor If the temperature should deviate from the normality various counteractions will be taken Under optimal circumstances the office has a computer controlled air conditioning and ERSP can immediately amend the situation Two different wireless sensors are used to read surrounding temperatures e MPR410 MICA2 motes 36 with attached MTS310CA sensor boards 37 operating at 433 MHz e MULLE 23 a wireless sensor communicating over Bluetooth 2 Background Positioning Model from Engine Ekahau Manager File Edt View Positioning Help am 42 la E E Logical Areas ie base 8 printer 4 corridor Access Points Value Type Average Y all CH 11 00 13 C4 F4 4B 50 cc wireless Combine Function Best v H o None AE oo y visible Contours Rough Fine G Devices tw accuracy Analysis 4 Coverage 2 Sianal Strengths jap Coordinates X Y Positioning Engine Status Open Figure 2 3 Ekahau Manger displaying network coverage for selected access points Figure 2 4 Ekahau Wi Fi Tag T201 15 2 Background 16 bL 90 0 0918 r o par o E o gt Figure 2 6 MTS310CA sensor board 2 5 1 MPR410
19. methods for handling moving and turning A thread is used for setting up a continuously running native method that at a specified interval reads static variables from the Move Java class The static variables consist of the position to move to and the angle to turn to There is also a possibility to change the linear velocity of the movement A complete description of the Move class can be found in Appendix B But how does the robot know when to turn and in what direction Before that can be an swered the robot needs some form of instructions on how to get to a position from its current position It needs to find a path and more explicitly find a path in the surrounding environment 3 1 7 Path finding The ERSP supplies three ways of finding a path but removing the ways that rely on the BEL only one way is available as stated in the ERSP API 12 e PathPlanner This method builds a graph of waypoints attempts to connect them and returns shortest length paths between given waypoints 3 Method 24 a x LI ami Szi Pia la E at Fo HF oF y Es ay ae 117 A we ii sities lle k f ES a l e a r meo rr ff PP y a HA 24 arai a am oS oe m wih Figure 3 1 Map of the surroundings used during this project This method will give an already complete way of generating a path between a start position and a goal But due to extent amount of waypoints needed to render a real world representation o
20. part c A computation of visual measurement is done in part b The computation makes a mea surement of where the robot is now and where it was located when the landmark was created The information gathered from the measurement are used to improve the localiza tion of the robot and of the location of the landmark In part c where the landmark could not be found a new landmark with its own unique number added to the features is being created The landmark is then initialized Step four returns the algorithm to the first step Path planning By using the vSLAM generated map path planning is done by computing a safe path between a start and a goal position Waypoints are then placed between the landmarks in the map Dynamic environment changes are not taken into account and are relied on the obstacle avoidance routines Obstacle and Hazard Avoidance Using the sensors the robot detects obstacles and generates the correct movement to avoid them Exploration A slowly increasing imaginary circle where the robot travels back and forth is used in the initial phase of the exploration The robot goes in a straight line towards the boundary of the circle and when it reaches the boundary it goes back to the interior in a random way This procedure continues until the preset radius of the circle or the preset time has been reached The next step for the robot is to improve the landmarks That is achieved by returning to previous landmarks
21. s location is read from the file written by the Main Settings menu BufferedReader reader new BufferedReader new FileReader settings txt ip reader readLine reader close In much the same way as the server the client associates two object streams with the socket allowing objects to be sent between the client and the server Socket socket new Socket ip 8189 ObjectOutputStream outStream new ObjectOutputStreanm socket getOutputStream ObjectInputStream inStream new ObjectInputStream new BufferedInputStream socket getInputStream The client consists principally of two things a loop that parses messages from the server and a send method that consigns messages to the server Firstly the loop determines the type of the received object then parses it accordingly and finally waits for a new object to arrive The send function simply tries to send the object passed along as an argument to the server it uses a ReentrantLock to prevent race conditions while true Object object inStream readObject if object instanceof String ConsolePanel addLine String object else if object instanceof DisconnectPacket jpgReceiver close ConsolePanel addLine Disconnected from the robot server break else if object instanceof PictureSizePacket PictureSizePacket packet PictureSizePacket object long pictureSize packet getPictureSize jpgReceiver setPict
22. the pre compiled program into the mote and does not recompile the application thus being significantly faster The syntax is accordingly make lt platform gt re install Moreover there are several programming boards available Hence the one in use must be spec ified either at the command line or in a Makefile Since a MIB510 serial interface board is used connected to the COM1 port lt programmer gt and lt port gt should be mib510 and coml respec tively Instructions on how to use a Makefile can be found in 3 The definitive syntax is make lt platform gt re install lt n gt lt programmer gt lt port gt Here lt n gt is a unique node address which allows multiple motes to share the same radio channel Each TinyOS message contains a group ID in the header which allows the system to filter out messages and separate motes Setting the node address ID during program load is not manda tory The following line illustrates how to install an application into a mote with group ID set to 10 using a MIB510 programming board connected to the COM1 port make mica2 install 10 mib510 coml Appendix G Establishing a PPP connection to the MULLE Dynamically setting up PPP connections to the Bluetooth MULLE necessitates interaction with the environment in which the Java application is running This is accomplished by obtaining a unique instance of the class Runtime from the getRuntime method Runtime rt Runtime getRuntime
23. to 9 a voltage offset 600mv must be subtracted before determining the temperature The complete course of action can be viewed in Appendix H For information about how the temperature is sent to the client see next section 3 5 Client Server The Java application created for this project is divided into a common client server model In the vicinity of the base station should a computer running Microsoft Windows have the client installed and running The server resides on the mobile robotic device that moves around and collects sensors readings 3 5 1 Server The server is principally a continuous loop that reads and parses objects sent over the network How the server is set up and sends and receives messages can be viewed in Appendix I The received messages can be of the types SteerPanelPacket A packet that contains information about how the user wants the robot to move generated from the steering panel in the GUI EkahauPacket This packet is sent when EPE update the location information about a wireless device It contains information about current location map scale and which logical area the device is currently visiting ImagePanelPacket Generated from the ImagePanel in the GUI that displays the floor map it contains all waypoints landmarks and goals that were added to the map DisconnectPacket Sent when the client desires to disconnect from the server The server handles all communication with the wireless sensors and ho
24. written to support this but due to the inaccuracy of the positioning system user generated events had to replace the initial idea In the best case scenario the average error from the positioning engine is one meter this is not good enough for a closed office space Without an impeccable object avoidance algorithm the robot would frequently collide with the office furniture The positioning engine can provide a rough estimate but are not something that the robot can solely rely on It is in our Opinion that this is the most important factor that should be ameliorated for an evident success If EPE could solely be used for pinpoint and navigate objects even in narrow passages it would be insurmountable 4 3 3 Combine software based with hardware based One thing that ought to attain a better accuracy is if the software based location system could collaborate with a hardware based system This would be more expensive and lay claim to a careful hardware setup still if high accuracy is invaluable this might be the solution How the different approaches should cooperate is not clear but might be something to bear in mind 4 4 Enhancements for MICA motes 4 4 1 Reduce energy consumption Due to the lack of time the application used to transmit temperature measurements from the MICA motes wastes energy It periodically sends data readings in spite of absence from a re ceiver The optimum solution would be to make the MICA motes transmit sensor data mer
25. 2006 283 CIV MASTER S THESIS Design Implementation and Evaluation of a Self controlled Sensor reading Scorpion Robot using Ekahau Positioning System Wireless MICA2 Motes and a Bluetooth Mulle Daniel Larsson Sebastian Sj din Lulea University of Technology MSc Programmes in Engineering Computer Science and Engineering Department of Computer Science and Electrical Engineering Division of Computer Science 2006 283 CIV ISSN 1402 1617 ISRN LTU EX 06 283 SE DESIGN IMPLEMENTATION AND EVALUATION OF A SELF CONTROLLED SENSOR READING SCORPION ROBOT USING EKAHAU POSITIONING SYSTEM WIRELESS MICA2 MOTES AND A BLUETOOTH MULLE DANIEL LARSSON SEBASTIAN SJODIN SEPTEMBER 13 2006 Abstract New state of the art technologies that revolutionize their areas emerges unceasingly To sustain usability and continue evolving these technologies should be subject to new ideas This can be achieved in different ways but one efficacious way is to synthesize technologies to reveal independent information about weaknesses and possible improvements As an outcome the need for compatibility can be analyzed and new usage areas can be ascertained In accordance this thesis is an attempt to combine a robotic device with a positioning system for office spaces various wireless sensors and a small embedded system which communicates using Bluetooth These technologies have their own interfaces and runs on different platforms The aim for
26. 4 5 3 Documentation se e sea aad ee ee 4 6 Enhancements for Mica 4 6 1 Aprogrammable interface lt s 2 0 0 00 00 natania etsas 4 7 Software prototype usage areas a 4 7 1 Aircondition controller e ea a e E O e an E 472 Surveillance csi epee ibaa aiia Oa a ai ee ee a Be Aa 4 8 Is there a need for extensive analysis of compatibility 4 9 Combining technologies a concise method for uncovering improvements 410 Evaluation ect da a Oe i AA ERR RE ack a ee ea ia 4 10 1 Educed software prototype lt o s s c s pia siia doe ee 4 10 2 Is the robot self controlled oaaae 4 10 3 Alternatives to Java nanana aaa ee 5 Conclusion Chapter 1 Introduction 1 1 Problem area This project is an attempt to combine a Scorpion 15 robot with the Ekahau positioning system 9 wireless MICA2 motes 34 and a Bluetooth MULLE 23 embedded system with sensors in order to create a self controlled robotic device that will read data from the sensors The sensors will be located at appointed positions From Ekahau a position for the robots location and logical areas for where to read sensors can be retrieved The sensors will give the current temperature at its location within the logical area To allow some form of platform independence the programming language used throughout the project will be Java 1 2 Purpose The main objectives of the project are e To attain knowledge in the stipulated areas
27. 80 p a PEG eG G Wireless Senggot iou o aoe a m bee bok we Bete ewig a ale hae ee awed 2 5 1 2 5 2 2 5 3 2 5 4 2 5 5 MIPRATO dci a ads Hw A we See Ha ad oe Sagres MTS310CA A eoi m eee Be ek eee OR ae AM eae goed Gea MICA2DOT ei 3 a 6 ete PES aaa De wee ee eee eo MIBSIOCA as seaside o Rica a AE Say GB pena a om a Se eae MULLE soraa e ba dot Song kee PAGS PRES ERNE dd ai Languages and software kas ionia dea a a eia a a E Eaa ETE OE E e SE 2 6 1 2 6 2 2 6 3 2 6 4 2 6 5 Java Native Interface o A ae augus mot Se fay a aane tee aap ae ak as Bg ari We a hoe Soke ae ONO Sa fe Ss ha REARS RE MoS ORG de A a hA a CY SWIM bbc S ee Haye Hed Bon os BREE at ee MEITE Flasher yaa ad hee atk ee a gee Set hoe gas ete 2 7 Hardware and software requirements o o o 3 Implementation 3 1 Scorpion s sesa A A Ra 3 2 3 1 1 3 1 2 3 1 3 3 1 4 3 1 5 3 1 6 3 1 7 3 1 8 3 1 9 Installing and configuring the ERSP o o o o o ooo o Testing the Scorpion TObOt e sacs a g hee ae Bee ae we a Gee a Analyzing necessities sc e nesei DER e A The HAL the BELorthe TEL 3 s isa ri e lr DOSISM isc pts ii y ae A a wae ees Navigation eco cabs ada aaa Pa e Se ae Pe See Bao Path finding vo ee hae eos ee al a Obstacle avoidance o sedi ticd o Et dae eae ae Sea Ek hati aa o A ee Bey ao ee Se Pt GS erates eS ce 3 2 1 A O ete th 3 0 MICA sensors 3 224664854646 h8 40h se Pes Rb Se RSS G
28. AN Access Point NAT Network Address Translation PDA Personal Digital Assistant PPP Point to Point Protocol Python An interpreted programming language RGB Red green and blue A color model RSSI Received Signal Strength Intensity RTLS Real Time Location System Scorpion A robotic device maintained by Evolution Robotics SDK Software Development Kit TCP Transmission Control Protocol TEL Task Execution Layer USB Universal Serial Bus ViPR Visual Pattern Recognition vSLAM Visual Simultaneous Localization and Mapping Wi Fi Wireless Fidelity WLAN Wireless Local Area Network XML Extended Markup Language Appendix A JNI and native libraries Writing native libraries can be done step by step 1 A Java class for declaring the native methods is needed In the thesis a class Move is present and this will be the Java class named Move java In this class a native method named startUpMove is present and declared as follows public native void startUpMove int updateFreqMicroSec In the Mova java file there needs to be a line that tells Java to load the native library that will be created static System loadLibrary Move Under Linux this will load the shared library 1ibMove so and under Windows Move d11 2 The Move java file needs to be compiled and javac can be used for this 3 To generate the needed header file javah jni can be used This header file will contain the function prototype for the native
29. MTS310 sensor board an approximation from 37 is used to convert it into degrees Kelvin This approximation is only valid if the tem perature is within the interval 0 50 degrees Celsius a a b ln Rinr c In Repr 3 1 where R1 ADC_FS ADC ADC a 0 00130705 b 0 000214381 c 0 000000093 R1 10kQ ADC_FS 1023 Rinr ADC output value from mote s ADC measurement T K temperature in degrees Kelvin Once T K has been calculated it is a straightforward task to calculate degrees Celsius Temperature Celsius T C T K 273 15 Furthermore the received TinyOS message includes the unique group ID that is used to deter mine which sensor made the transmission The corresponding local variable is updated and can later be retrieved through its get method Detailed information about how the temperatures received from the mica sensors are sent to the client can be found in section 3 5 on page 29 3 Method 28 Figure 3 3 RS232C Level Converter 3 4 MULLE 3 4 1 Hardware setup The first step is to furnish the MULLE with a suitable power supply Since the current varies vigorously the MULLE should be powered either by a battery that delivers 3 7VDC or through a voltage regulator using a resistor to reduce the voltage is indecorous Unfortunately neither a suitable battery nor a voltage regulator where available at Caulfield campus consequently a voltage regulator kit was bought an
30. OR DES EER Boil SOW ALC ma da Se Ge aid a acer a A S we Awe Qe ks We A de Silo MULLE aa ae Bah dich Sete A vhs Bap A de La ade IG ed 34 1 HordWareSetup os sou a de Bow or WR p Re AR A 3 4 2 Connect and receive temperature from the MULLE 3 5 Client Server sa cs dee ea kG aa na IDA GEVE acia e ER eR Ewa PEAS NA oe B02 Cenie siti ooh 2 E aoe ae ee ee oh we Sl 4 Discussion AA Problems iii ws We BS oe eis Bee Se ae DA Roh BY St Soe Bd 411 SCOrpiOn TOOL 4 4 4 4444 eee a ORR EE OE Ee ER AWD ARIANA fs aras lia a GY Ae ees ei he as e Gee rg ae Sica ae Ge ee AI OMULLE a te cee Ae Gh aw oes ws Se SS Sa eg Oe ee a ee A 4 2 Enhancements for Scorpion ER1 and ERSP 2 2 022 ee o 4 2 1 Physical limitation soi usa e ee 42 2 Environment carros 2 a 2 be aR ORG RR EPS SR ee a 4 2 3 Deficiencies in the ERSP API 4 2 4 Obstacle avoidance for moving objects aooaa aa 4 2 5 Builtinapplication o 4 3 Enhancements for Ekahau ee 4 3 1 Operating system independency ss sssaaa areata rae dia ami 43 2 Better accuracy s 4 444 penea A A a A 4 3 3 Combine software based with hardware based 4 4 Enhancements for MICA motes 4 4 1 Reduce energy consumption s kaaa ei s eee pa a ee 4 5 Enhancements for MULLE ee ee AD Battery eens vice cide al e a o Be cea hot aah a eh Bees 4 5 2 Update firmware via Bluetooth 2 2 2 eee
31. SP is quick and easy An install shell script is supplied and will use the Advanced Packaging Tool 1 APT to retrieve and install the required packages The installation will place everything related to the ERSP under the location opt evolution robotics For the purpose of making the ERSP working correctly with the Scorpion robot some mod ules needs to be loaded into the Linux kernel and configuration files must be changed There is a module named ftdi_sio o that is used to communicate with the Scorpion s Robot Control Module Loading this module will attach the device to the dev ttyUSBO file descriptor The IR sensors that are connected using USB depend on a module named legousbtower o One must make sure that this module is loaded before the usbhid o kernel module otherwise the sensors will not be found A file descriptor named dev usb evodev0 is used for communcat ing with the sensors To make the camera a Logitech Quickcam in the case of the Scorpion robot work the ov511 0 module needs to be loaded The file descriptor dev video0 will be used for getting data from the camera 3 1 2 Testing the Scorpion robot To get an overview of how the robot works the test programs that comes with the ERSP is useful The Client GUI application provides means to navigate the Scorpion and to get a video stream from the camera Some important results from the testing e The time between action for movement and the actual robot movement is notab
32. The exec method executes the command given as argument in a separate process and returns a Process object for managing the subprocess Here hcitool is used to search for Bluetooth devices and their respective addresses Process p rt exec hcitool scan This will however return all reachable Bluetooth devices not just the desired MULLE That is where the subprocess p comes to assistance getInputStream obtains data from the standard output stream of this process BufferedReader in new BufferedReader new InputStreamReader p getInputStream The MULLE s Bluetooth address can be found by searching through the character stream and check whether the current line contains the name of the Bluetooth device Calling the trim func tion assures that the string object contains no leading or trailing whitespaces Finally the Blue tooth address is extracted via the substring method which creates a new string object beginning at START and extends to the character at index END 1 while line in readLine null f if line contains SEQUENCE line line trim address line substring START END break Once the Bluetooth address is know it is used in conjunction with dund to create the PPP connec tion to the MULLE rt exec dund c address Appendix H Connect and receive temperature from the MULLE Creating a TCP client socket that is connected to the MULLE
33. There are tasks available for navigation networking resource speech utility and vision Obviously navigation and vision are important parts of the architecture and they will be described later on 2 3 1 ERSP architecture For simplicity the ERSP consists of three layers the Hardware Abstraction Layer the Behavior Execution Layer and the Task Execution Layer Hardware Abstraction Layer Abbreviated HAL is the interface between the applications and the hardware Using physical devices like a camera and range sensors the HAL receives information about the surrounding environment The interaction between the physical world and the low level operating system dependencies are done by the HAL drivers Using resource drivers which are software modules that allow access to a resource one can interact with the underlying resources like physical devices such as sensors microphones ac tuators network interfaces battery and speech recognition systems This can be done from the operating system or other API function calls The resource functions implemented by the driver are dependent on the operating system and the device specifics A number of well defined interfaces are provided by the HAL These interfaces which are a set of public C abstract classes protect higher level modules from OS dependencies The resources are made up of three subtypes Bus A transport layer to access external devices Examples are USB serial and Ethernet
34. This is achieved by having a Boolean variable in the Move class that is true when moving is in progress and false otherwise Its state is then returned to false after they wait has been done try while move isReady false sleep 200 catch Exception e System out println e move setReady false To know in what direction the robot should move next the x position for the next move is stored in the variable xnext if i size 2 1 break else xnext Xcords i Xcords i 1 Analyzing the differences between the xnext and xfirst variables tells in what direction the robot must turn After this the xfirst variable is updated and the count variable is reset if xnext xfirst if xfirst xnext 1 move setAngle 45 else if xfirst xnext 2 move setAngle 90 else if xfirst xnext 1 move setAngle 45 else if xfirst xnext 2 move setAngle 90 xfirst xnext count 0 So the Exploration class handles the movement between two waypoints but there needs to be something that handles the waypoints This is done by the FindPath class The public methods in the FindPath class are the following e void makeMove int WPs e int getCurrentGoal e int setGoalWP int goalx int goaly e void setCurrentGoal int index e void run e void addWayPoint ArrayList lt int gt array e void addWayPoint int x int y
35. ance There are two more concrete methods to avoid getting too close to stationary and moving obsta cles e Using the camera and object recognition e Using infrared sensors Since the camera is stated to be used for retrieving a video stream necessary when helping out the robot in stuck situations it can not be used for obstacle avoidance simultaneously However the object recognition for the ERSP relies on images and a possibility to make object recognition useful is to ensure that the video stream is made up of a sequence of images But due to the amount of CPU power used by this solution for the camera see section 3 1 9 on page 25 and the limited need of object recognition there is only a need to find objects that are in the way the IR sensors seemed like a more convenient method for this aim The process to obtain the IR sensors and to read data from them is very straightforward Logically the sensors are named after their location on the physical robot An array of the sen sors is created to be used when obtaining the interface to each of the sensors Every sensor will give data on how far away an obstacle is and a maximum distance can be set Defining an explicit distance value for each sensor is necessary and if an obstacle comes within this range countermeasures must be taken In a first simple method any obstacle appearing on the sides of the robot will turn the robot in a small angle in the opposite direction just to avoi
36. and exploring every unexplored space of it Occupancy grid mapping Combining vSLAM with obstacle avoidance will create an occupancy grid map The map is an overhead picture of objects in the robots view In order to keep the map up to date vSLAM provides information about where in the map the robot is and obstacle avoidance detects obstacles and then adds them to the map 2 Background 13 2 4 Ekahau positioning system Ekahau Inc 9 is the sole proprietor of a software based real time location system The approach of Ekahau Positioning Engine EPE is measuring signal strengths from a wireless network This software based approach offers the highest positioning accuracy available and according to the Ekahau homepage 9 outperforms competing technologies such as signal propagation and tri angulation EPE can track various 802 11 enabled devices such as laptops handhelds and the Ekahau T201 Wireless Fidelity Wi Fi tag Ekahau Client must be installed and run on each lap top or handheld that should be found by EPE The network reader component is currently only available for Windows XP Windows 2000 and Pocket PC 2002 2003 EPE software based technology is not just accurate it facilitates a fast implementation with an affordable cost It can make use of existing wireless network infrastructure and is compatible with all standard 802 11a b g Wi Fi access points For EPE to function optimal at least three Wireless LAN WLAN access point sh
37. ardware setup Because of Ekahau Clients limited operating system support as briefly discussed in section 2 4 the EPE can not directly track the robotic device since it is controlled by a laptop running Fedora Core Attaching an Ekahau Wi Fi tag to the robot would be the natural solution to circumvent this However the available tag malfunctioned and another solution had to be used The selected alternative was to place a Wi Fi enabled PDA running Pocket PC 2003 on the robot Both Ekahau Positioning Engine and Ekahau Manager are installed on a laptop running Microsoft Windows XP 3 2 2 Software The location based client establishes a connection to the positioning engine through the Java API and registers listeners that receive location information about the desired wireless device The implementation supports tracking of multiple wireless devices even though this project only tracks the ER1 robot thereby making it more applicable Detailed information about how to connect and communicate with the positioning engine is described in Appendix E Figure 3 2 illustrates the Ekahau concept used throughout this project More information about how the location based GUI communicates with the robot server can be found in section 3 5 on page 29 3 3 MICA sensors The components used in the wireless sensor network setup are e One MIB510 interface board 3 Method 27 e Three MPR410 processor radio modules e Two MTS310 sensor boards 3 3 1 So
38. ctly call the MULLE s get method Firstly a new thread is created this circumvent the application from stalling Secondly the MULLE s start method is called which sets up a PPP connection to the MULLE and creates a TCP connection that is used to update the variable holding the temperature data Finally the get method can be used to receive the new temperature if logicalArea equalsIgnoreCase meeting if busy new Thread new Runnable public void run busy true Mulle mulle mulle start temperature ME busy false new Mulle ETING mulle getTemperature start When the robot approaches the proximity of the base station the array containing all three tem peratures are sent to the client which in turn updates the GUI if ServerThread isConnected ServerThread send new SensorPacket temperature Appendix J Client Before connecting to the server the logger is initialized it outputs its data to the file log txt The data can latter be scrutinized either from the GUI or from a normal file reader Logger logger Logger getLogger src Scorpion Network Client try FileHandler fileHandler new FileHandler log txt true fileHandler setFormatter new SimpleFormatter logger addHandler fileHandler catch IOException e e printStackTrace The IP address that narrates the server
39. cts with three dimensions can also be recognized reliable but the objects should not be deformable in order for the system to manage the recognition correctly Character istics that make the object recognition work properly are variations to 14 Affine transformations and rotation Rotated objects and objects placed at a different angle with respect to the optical axis are recognized Scale changes Objects at different distances from the camera are recognized Lightning changes Recognizes illumination changes from natural to artificial indoor light ning Also insensitive to objects caused by backlights and reflections Occlusions Objects that are partially blocked in an amount between 50 to 90 percent are easily recognized If N is the number of objects in the database the recognition speed is proportional to log N 14 The object recognition algorithm has three main steps Training The number of views needed per object depends on the object type planar or 3 D One or more images are taken for each view 2 Background 12 Recognition For each object the algorithm extracts up to 1 000 local and unique features When recognizing an object a subset of this feature is identified Estimation The correct object name and full pose is provided by the identification Image processing is used for optical flow computation color detection and color tracking One feature with color tracking is skin detection so the robot can
40. d a hit by the side A second recursive method tries to go around an obstacle or break out from a stuck situation It should be noted that these methods does not work correctly due to the unexpected results that the DriveStop and Stop methods does not fully comply with what they are sup posed to achieve and due to time constraints For a more complete description of the IR sensors see Appendix D 3 1 9 Camera One way to implement the camera is by using the HAL which allows configuration of the cam era However using this method resulted in the strange error that an image could not be cap tured The TEL and the available task Get Image worked directly but the configuration pos sibilities are lost In order to reduce image size and by so the size of data that needs to be sent to the GUI the image is downscaled before it is stored This is all done in the native method takePicture that is called from the Camera Java class To create a streaming effect a picture is taken every tenth of a second In the Camera class a JPGSender object is constructed and is used to send the images to the GUI The JPGSender uses the Java NIO to effectively send data via file channels 3 Method 26 Server Manager Laptop PC Client Location Robot Server Based GUI PDA Client Ekahau Positioning Ekahau Client Engine Network Card Ekahau Manager Ekahau Client Network Card Figure 3 2 Ekahau conceptual model 3 2 Ekahau 3 2 1 H
41. d soldered together Once the MULLE receives an appropri ate voltage it starts up and executes its firmware by default this meant searching for a Bluetooth LAN access point and start uploading data to an Embedded Internet System Laboratory EIS LAB server at Lule University of Technology Sending data between Australia and Sweden is unpractical and therefore a new firmware was necessary Re programming the flash memory of the MULLE requires numerous preparations Firstly a programming adapter has to be attached to the MULLE allowing it to receive data from a PC Secondly short circuit pin 5 and 15 to set the MULLE in its programming mode Thereafter should pin 2 RxD 3 GND 4 TxD and 15 VCC be connected with corresponding pins from the computers serial port The voltage difference between the computers serial port and the MULLE is managed by a RS232C level converter 11 This level converter consists of a MAX232 circuit together with four capacitors as illustrated in figure 3 3 Connecting and uploading the new firmware to MULLE is carried out by the M16C Flasher program Finally remove the short circuit between pins 5 and 15 to set the MULLE in its run mode again 3 4 2 Connect and receive temperature from the MULLE With the current firmware the MULLE waits for a Point to Point Protocol PPP connection over the LAN Access Point LAP profile One way to establish such a connection is using the two UNIX commands hcitool and dund Th
42. e C tasks However using TEL the configuration becomes limited Since BEL uses XML and the integration of more languages is not encouraged HAL and TEL will be the layers of use 3 1 5 Design There are four major parts of the ERSP that are needed for this project e Navigation e Path finding e Obstacle avoidance e Camera The navigation will contain all the movement and some functionality to avoid objects since this is hard to implement anywhere else Path finding will consist of classes to find a path between specific waypoints in a map Obstacle avoidance will be done by ina class that uses the IR sensors and the camera will be used in a single class to retrieve images 3 Method 23 3 1 6 Navigation Both HAL and TEL provides ways of navigating the Scorpion Here are the available classes for moving and stopping MoveTo Moves the robot to a set of absolute coordinates Specifications in the form of a timeout x and y coordinates velocity acceleration and a distance from coordinates can be set MoveRelative Moves the robot to a set of relative coordinates Specifications are the same as for MovelTo Stop Stops the robot and will cancel any Move method that is in progress The hardness of the stop can be set DriveMoveDelta Will command the drive system to move a specified distance Velocity and acceleration can also be specified DriveStop Will command the drive system to stop For stopping DriveMoveDelta Accordingly th
43. e for selected access points 15 Ekahau Wi Fi Tag T2010 aia hak Ge ee BE we a we ee 15 MPR410 MICA2 mote 6 2 5 oie a e rs eek Yara de Gee i 16 MTSSIUCA sensor board iia cerros tes a dd Dee haa 4 16 MICA2DOT MOt S sa 505 aoe eG Ba wars Bee oe em ee a ee 17 MIB510CA interface board o o 17 The MULLE wireless sensor networking platform o o ooo 18 The Eclipse framework sac mesae sa sna ti aa aa a AORA a a a ea eS 19 Map of the surroundings used during this project aooaa 24 Ekahau conceptual model cuidara Be a e E as 26 R5232C Level Conv rtel s parias ee ane is ee De Bw e Ged 28 ClentGUL Stine ede WR Seed ROR e PARAS RSE REA a Sa 30 Contents 1 Introduction Problemata renei ia erecta He Gh a Bee HR ween he Blea a e Bo ee We ded aa 4 Purposes hha ad Ge ee Rea PES OAR Gh Ree eee ae SAS De limitatons a csi ce ee Ge ik es cae ke a wa we me n de a OURE 4 a cache eed Be Sock Ba eat Je 8 oh Aya Bebo Re ee Le ie ee a Contrib Won lt 4 4 ara A wih ae Shas a a Ok a es Be eee 2 Background SCOLPION LODGE moi e a a a a ee a eee ER TODOS acaso e ae Sock Ads te oh Ga hy a ne Evolution Robotics Software Platform 2 1 2 2 2 3 2 4 2 5 2 6 2 3 1 ERSP architecture 4 2 25 44 ac64s hoe ahah eee ea AL SSS Ekahau positioning system 6 ee 2 4 1 2 4 2 Ekahat manager a 2G caw eae dee Oe Ae BERR EEO Ow Res Ekahau Wi Fi tag 1201 22 252 2440
44. e latter is used to set up the PPP connection over LAP us ing rfcomm whereas hcitool is used to scan for the Bluetooth address needed by dund Appendix Gillustrates the procedure in Java Once a connection is properly set up it should be possible to send a ping request to the MULLE on the Internet Protocol IP address 192 168 0 1 The best method to receive the raw readings from the LM61 temperature sensor is to create a TCP connection to the MULLE When the MULLE receives a START command over the created TCP connection it will begin trans 3 Method 29 mitting data in packets of two bytes containing the 16 bit number from the Analog to Digital Converter ADC Since the bytes are sent in little endian format while Java Virtual Machine JVM uses big endian format some byte arithmetic is necessary to receive a faultless reading e Little endian the least significant byte of any multi byte data field is stored at the lowest memory address e Big endian the most significant byte of any multi byte data field is stored at the lowest memory address After the byte arithmetic operations the received value should be in the interval 0 1023 Since the temperature sensor has a nominal output voltage ranging from 0 to 2 5 volt a corresponding value can be calculated The LM61 s output voltage is linearly proportional to the temperature which means that an increase with 10 milli Volt mV is analogous with a raise of one degree Celsius According
45. e most useful method for moving the robot forward would be using relative co ordinates since it is under the assumption that Ekahau will provide the robot with its current location However the MoveRelat ive method results in an unexplainable exception when try ing to execute it two times consecutively The same occurs with the MoveTo method Gladly the DriveMoveDelta method is error free The navigation needs to be independent in order to run several methods simultaneously One way is to use the Parallel class that comes with the ERSP This will allow tasks to run asynchronously Consequently a lot of the communication between tasks must be done within the C native methods and not within Java which will complicate the communication process However Java has thread support and threading is a much more convenient solution for this project A possible drawback though is a loss in efficiency DriveMoveDelta does not comprise in any turning of the robot There are however two methods in the ERSP that can manage this TurnRelative Will turn the robot to a relative angle The angle and an optional angular velocity can be specified TurnTo Will turn the robot to an absolute angle with the same specifications as above A relative turn to the robots position fulfils the demands of turning Moving and turning is what is needed for moving around The Java implementation of the navigation is done in the class Move This class consists of native
46. e seen in figure 2 1 on page 9 2 2 ER1 robot The ER1 robot also maintained by Evolution Robotics is equipped with the following features 3 IR range finder sensors A Robot Control Module similar to the Scorpion Rechargeable 12V battery and charger USB interface Cushioned cradle for laptop computer Wide angle calibrated video camera with precision tilt adjustment The use of the ER1 robots was not initially planned It was only thought of as a comparison robot to the more complex Scorpion robot but due to some mechanical errors it became the robot of use half through the project The ER1 robot is shown in figure 2 2 on page 9 2 Background Figure 2 1 Evolution Robotics Scorpion robot Figure 2 2 Evolution Robotics ER1 robot 2 Background 10 2 3 Evolution Robotics Software Platform Evolution Robotics Software Platform ERSP is a trademark of Evolution Robotics and is made up by a number of software modules These modules are components containing a broad range of drivers tasks and behaviors The ERSP Application Programming Interface API is written in C and contains a sub stantial number of libraries behaviors and tasks They are all divided into parts that describe their functionality Some of the more extensive libraries are base behavior GUI math naviga tion resource task and vision while some of the more extensive behaviors are emotion GUI navigation resource speech and vision
47. ely when a receiver is present However this requires an extensive revision of the already modi fied code Furthermore rewriting code for the MICA motes requires comprehensive knowledge of the programming language nesC and the TinyOS model Hence it has been left out as an improvement 4 5 Enhancements for MULLE 4 5 1 Battery The first problem that revealed itself was finding a suitable power supply In our case the MULLE is powered with a voltage regulator However a voltage regulator is lumbering and devastates the otherwise small and mobile MULLE It would be convenient if the MULLE had a small built in battery 4 5 2 Update firmware via Bluetooth Changing the behavior of the MULLE requires an update of its firmware This is an arduous task that should be made more user friendly Firstly a connection has to be established over the serial channel Secondly a level converter has to be used to shun burning the MULLE Finally the MULLE has to be connected according to a special wiring diagram It would spare the user a 4 Discussion 34 great amount of time if the firmware could be uploaded via Bluetooth This would require a few additional circuits but should not be impossible 4 5 3 Documentation The most important improvement for the MULLE is the documentation This is something that has been made clear to the developers and should be arranged at their earliest convenience Without an exhaustive conversation with Jens Eliasson
48. est length from the start position This waypoint is then added to the retArray integer doublearray and the value for this index is set to a maximum so it will not be used again The returned array will by so contain the waypoints in the order the robot should move int 1 retArray new int sizer length 1 2 retArray 0 0 start_x retArray 0 1 start_y for int i 0 i lt sizer length i int index getMinIndex sizer way waypointList get index retArray i l way sizer index 999999999 return retArray Appendix D IR sensors class To obtain the IR sensors are pretty straightforward There is a thread running continuously that sets the readings from the sensors in static variables in the IRSensor java class It looks like this in the case of the ER1 robot while isRunning for int i 0 i lt NUM_SENSORS i double distance Timestamp temp_time result ir_sensors i gt get_distance_reading NO_TICK amp temp_time amp distance E H if result RESULT_SUCCESS cout lt lt Failed to obtain distance reading for sensor lt lt SENSOR_ID i lt lt endl return if SENSOR_ID i IR_tne env gt SetStaticIntField cls ne_sensor_id int distance else if SENSOR_ID i IR_tn env gt SetStaticIntField cls n_sensor_id int distance else if SENSOR_ID i IR_tnw env gt SetStaticI
49. f moving objects like a walking person Since the camera also has a delay real time obstacle avoidance will be hard to achieve with the Scorpion and ER1 Adding laser sensors would im prove the time for detection of obstacles 4 2 5 Built in application Since the Scorpion robot and the ER1 robot needs a laptop mounted in order to run applications a lot of flexibility is lost A possible solution is to upload an application to the robot that stores it for example on a harddrive However this approach will result in a loss of extensibility so some way of adding extensions is necessary By adding USB outlets this could partly be avoided 4 3 Enhancements for Ekahau 4 3 1 Operating system independency One of the major problems in combining different technologies was managing the demands they put on the underlying operating system It has also been noted that operating system such as 4 Discussion 33 Linux and Mac OS X are continuously increasing their number of users Attaining a broader user group and making their products more adaptable ought to be in the companies best interest and hopefully something that will change at their earliest convenience 4 3 2 Better accuracy The original thought was that EPE should continuously send which logical area the robot is visiting Supposing that it was inside the logical area where the Bluetooth MULLE is located the robot server activates and connects to the MULLE All necessary Java code is
50. f the area where the robot can move around and since the vSLAM application can not be used another way of accomplish the path planning is necessary The ERSP has a class named OccupancyGrid that can be used to represent a grid structure containing information about for example the surroundings In order to do that a map of the surroundings is needed Figure 3 1 on page 30 represent the image map used throughout this project for generating the grid A grid based on this image map will be created and this grid can be used by the robot to find out where obstacles are located Obstacles in this case can be walls or other real world stationary objects Since Ekahau also relies on a map of the environment to point out positions the same map will correspondentlyy be of use for the robot See section 3 2 on page 26 for a description of how Ekahau utilizes the map As an extension to the OccupancyGrid a class named ExplorationGrid is present This class can be used to find the shortest path between two x and y positions in the complete grid To load an image map of the surroundings the Imagelo class available in the ERSP is used The width of the map is necessary in order to create an OccupancyGrid object In order for the OccupancyGrid to generate an appropriate complete grid of the map every pixel in the map where the robot can move needs to have RGB 33 values of 255 With RGB values of 255 the corresponding grid square of that pixel will be set as
51. ftware Before the MICA2 motes can read and wirelessly transmit temperature measurements a TinyOS application has to be installed into the mote Appendix F elucidates how to compile and in stall an application using Cygwin The two motes that operate as sensors have a modified ver sion of OscilloscopeRF installed In its standard design OscilloscopeRF periodically takes readings from the photo sensor and sends them over the radio channel The modified version functions much in the same way besides utilizing the temperature sensor It is of the outmost im portance that two different group ID s are assigned when programming the motes as discerning them would be impossible otherwise The third mote which is connected to the MIB510 inter face board is running an application called TOSBase that acts as a bridge between the wireless and the serial channel Once the data is made available for the serial port another program SerialForwarder takes over SerialForwarder is a Java program that reads TinyOS mes sages from the serial port and forwards them over a TCP connection to connected clients This means that other programs even running at another machine can communicate with the sensor network via a sensor network gateway In this project the robot server connects to the SerialForwarder program and registers a MesssageListener object that will be invoked when TinyOS messages arrives The received TinyOS message contains the raw ADC output from the
52. ieved e Source code and libraries is it written so that it is easy to extend Analyzing the technologies used in this project there are some parts that could be improved For the products by Evolution Robotics the main thing that is missing is a complete API in Java This would have removed the use of the Java Native Interface that has caused a lot of time consuming problems Moreover it would have allowed the use of more methods For Ekahau not supplying a client for Linux is limiting Furthermore TinyOS uses nesC and will limit any further extensions How can improved compatibility be achieved Since the common life cycle of software which consists of nine phases as specified in 2 is exercised by many developers an inevitable addition to this life cycle would be compatibility Adding compatibility as a part of the specification and design phases would reveal in a product that is more prepared for extensions Another way of improving the compatibility is by allowing targeted user groups of an up coming product to give reflections about their intended usage More usage areas will result in better specifications and a more concrete design 4 9 Combining technologies a concise method for uncovering improvements Analyzing a specific technology by using it and testing it during a precise period will probably uncover more individual improvements then combining a technology with other technologies for a period of the same length However
53. iki Gaussian_mixture_model Address valid as of April 17 2006 32 Hsv color space description http en wikipedia org wiki HSV_color_space Address valid as of April 17 2006 33 Description of rgb att wikipedia org http en wikipedia org wiki RGB Address valid as of May 3 2006 34 Crossbow technology inc homepage http www xbow com Address valid as of April 4 2006 35 Getting Started Guide http www xbow com Support Support_pdf_files Getting_Started_Guide pdf Address valid as of April 4 2006 36 MPR MIB User s Manual http www xbow com Support Support_pdf_files MPR MIB_Series_Users_Manual paf Address valid as of April 4 2006 37 MTS MDA Sensor and Data Acquisition Board User s Manual http www xbow com Support Support_pdf_files MTS MDA_Series_Users_Manual pdf Address valid as of April 4 2006 Glossary ADC Analog to Digital Converter API Application Programming Interface BEL Behaviour Execution Layer Bluetooth Short range wireless technology EIS Embedded Internet System EISLAB Embedded Internet System Laboratory Ekahau Positioning system for office spaces EPE Ekahau Positioning Engine ER1 A robotic device maintained by Evolution Robotics ERSP Evolution Robotics Software Platform GNU GNU is Not Unix GUI Graphical User Interface HAL Hardware Abstraction Layer IP Internet Protocol IR Infrared JNI Java Native Interface JVM Java Virtual Machine LAN Local Area Network LAP L
54. ioned technologies this project necessitates two laptops The first one located at the base station has the following demands in order to run Ekahau Positioning Engine e At least 1Ghz x86 CPU e 256 MB of RAM e 500 MB of free hard disk space e Wi Fi support e Java 1 5 SDK e Microsoft Windows 2000 2003 or XP The other laptop resides on the Scorpion or ER1 robot and requires 800Mhz Intel Pentium III CPU or higher 256 MB of RAM 2 GB of free hard disk space for installations Wi Fi support to communicate with other laptop Bluetooth support to communicate with MULLE RS232 serial port to communicate with MICA motes Three USB ports to connect robot Java 1 5 SDK Fedora Core 3 for ERSP to work Chapter 3 Implementation This section presents the design and implementation phase of the thesis It is under the assump tion that the reader prepossesses adequate Linux and programming skills in order to fully un derstand what is covered 3 1 Scorpion To be able to use the Scorpion robot the ERSP needs to be installed The installation is available for several operating systems and during this project ERSP was installed and run under Linux more specifically the distribution Fedora Core 3 One can question this choice of operating sys tem and a further discussion can be found under section 4 10 on page 35 3 1 1 Installing and configuring the ERSP After installing Fedora Core 3 the installation of the ER
55. ironment suddenly changes for example on both sides of a door e In large open areas construct a grid of Tracking Rails and record sample points in the corners of each square An immense advantage with EPE is that minor environment changes do not require the user to reiterate to calibration process Ekahau Manager is also used to draw logical areas on the map which can be used to check if a client is inside a specific area Furthermore it provides tools for carrying out positioning accuracy analysis and display the LAN coverage The latter can be viewed from selected access points and is very useful to find areas with poor network coverage Figure 2 3 on page 15 displays the network coverage of the 7th floor in the H building at Monash University Caulfield with four selected access points It also shows the robots possible travel paths together with three logical areas e Base e Printer e Corridor 2 4 2 Ekahau Wi Fi tag T201 The Ekahau Wi Fi tags are the core of the Real Time Location System RTLS They can be at tached to any mobile object allowing EPE to continuously track the target within the coverage of an 802 11 network The typical operating range is approximately 40 60 meters indoors depend ing on the network speed It has an intelligent power consumption that is based upon motion sensors and gives battery life up to several years The Ekahau Wi Fi tag is illustrated in figure 2 4 on page 15 2 5 Wireless sensors To
56. k code and a graphical interface Furthermore the authors were more familiar with Java so the choice of programming language was not soundly discussed Chapter 5 Conclusion Throughout this thesis the following work has been performed A research of areas concerning Evolution Robotics Scorpion robot Evolution Robotics Soft ware Platform Ekahau positioning system wireless MICA sensors and Bluetooth MULLE Scrutinize the possibility of joining existing technology into something new and useful Design and derivation of a software application that utilizes these stipulated areas in order to assemble a self controlled robotic device with sensor reading capabilities Solder electronic components and updating hardware via circuit boards Investigation of the viability of acquiring related weaknesses and improvements Evaluation of the educed software application bringing forth strengths and weaknesses After the project came to an end innumerable things were learned and these are some of the most important findings It is a nuisance having to reflect over system dependencies programming languages and hardware requirements Documentation can never be exhaustive enough It is feasible to combine the described technologies into a functional prototype This way of working is an excellent method for evaluating the modularity of a product or technology The time spent on planning and documentation in an early phase of the project is
57. kahau Due to the inaccuracy of the Ekahau Positioning Engine the robot can not solely rely on this software based tracking system for navigation In the best case scenario the positioning engine has an average error of one meter This is not good enough for navigating a robot in a closed office space since a door opening is approximately of that dimension Two factors contributed to an even higher average error Firstly an old version of EPE was used Secondly the network card used by the PDA was not officially supported by Ekahau Thereby no mitigation technology could be used and this typically causes a positioning inaccuracy of about 1 4 meters 4 13 MULLE The first real problem with the MULLE was the lack of documentation Furthermore not a single person at Monash University had previously even got it to start up The next problem was to find a power supply that delivers 3 7VDC Since a voltage divider circuit could not be used a voltage 31 4 Discussion 32 regulator was bought and soldered together Once the MULLE had an impeccable connection with a suitable power supply the next problem was detected it tries to upload data to an EISLAB server in Sweden This is both unpractical and requires an additional component a Bluetooth LAN access point Consequently a new firmware was needed for the MULLE Loading a new firmware requires communication over the serial channel Since the serial port of a computer operates with 12VDC a level co
58. lds the data until it is sent to the client when visiting the base station 3 5 2 Client The GUI provided by the client illustrated in figure 3 4 is the actor of the system and facilitates moving control over the robotic device It has a steering panel which can make the robot move in all direction and at different velocities Moreover waypoints and goals can be uploaded to the robot server by marking them on the map Once the robot server receives them it calculates the best route towards the goal Unnecessary waypoints are left out The video feed from the robots camera is convenient when steering the robot away from the user s field of sight or getting the robot out of locked situation In the GUI the temperature measurement from all three motes are 3 Method 30 Main View Help Main Camera Temperatures Printer NJA Corridor N A Meeting N A FE aes e di 5 IO SEKA t O Waypoint Upload to robot Add O Landmark ch on y Connected to the robot server Uploading to robot Location Buttons Base J Printer J Corridor J Meeting Figure 3 4 Client GUI also shown Important output and status messages will be shown in the console in the right hand bottom corner Finally the user can read a log of the temperatures that deviated from the normality under the view log menu The log includes which sensor read the erroneous temperature and at what time More detailed information
59. le e Stream delay from the camera is approximately half a second e Robot movement is slightly arrhythmic 21 3 Method 22 e Turning and moving the robot at the same time seems tricky These observations will in some way affect the implementation of the Scorpion robot 3 1 3 Analyzing necessities What is needed from the Scorpion robot From the depicted goal it is obvious that it should be able to 1 Move around Forward backward left and right This includes turning Get information about the surrounding environment for use when navigating Find a path between two points in the surrounding environment Get its current position Avoid stationary objects Avoid moving objects N DD FF Ae Q N Receive a video stream that is of importance when manually helping the robot out in hard situations 8 Be aware of where sensors are located 9 Wait for sensor data to be read 10 Run several methods simultaneously Since the applications supplied with the Scorpion can not be extended and used the ERSP API must be used to its full extent 3 1 4 The HAL the BEL or the TEL What layer is most suitable for this project Since the HAL provides interfaces in form of C abstract classes for interacting with the Scorpion its usefulness is not questionable HAL also allows configuration of resources As a high level task oriented interface to the BEL the TEL gives the advantages of actions made as easy programmabl
60. located which logical area that contains it and possible sta tus messages Finally the set Tracking method is called with the argument true to start tracking the wireless device for Iterator i devices values iterator i hasNext Device device Device i next TrackedDevice t new TrackedDevice device t setTrackingParameter numberOfAreas 2 trackedDevices add t t addLocationEstimateListener handler t addLogicalAreaListener handler t addStatusListener handler t setTracking true When automatic location information updates are no longer required for a device tracking should be stopped by passing the false argument to the set Tracking method for Iterator i trackedDevices iterator i hasNext TrackedDevice t TrackedDevice i next t setTracking false In the location estimate handler much information can be found about the tracked device The essential point is the current X and Y coordinates other important information subsumes speed heading and mapscale There are two approaches for receiving location information getLatestLocation The latest X and Y coordinates for the tracked device getAccurateLocation A more accurate location but with a short delay For this project the latter is chosen since an accurate position is of more importance than a fast and inaccurate one Location accurate locationEstimate getAccurateL
61. look for changes in the x and y variables Bear in mind that the x and y values are from the waypoints set in the client GUI and the MoveTo method is not working when executed sequentially Therefore a distance to move and an angle to turn to is needed When x and y are greater than zero we are in the first quadrant and turning right is according to the ERSP a negative turn The angle is easily calculated using the arctan function The same thing is done for to other three quadrants Then the angle is calculated into degrees and the distance is calculated if x xold amp amp y yold amp amp x 0 double angle 0 if x gt 0 amp amp y gt 0 angle atan y x else if x lt 0 amp amp y gt 0 angle M_P1 2 atan x 1 y else if x lt 0 amp amp y lt 0 angle M_PI 2 atan y 1 x 1 else if x gt 0 amp amp y lt 0 angle atan x y 1 angle 360 2 M_PI double distance sqrt x x y y Now the arguments are set and can be used for the TurnRelative and DriveMoveDelta methods First a turn to the right angle is needed Then a move can be done The total time for moving is needed when the move is interrupted by a detection of an obstacle done by the IR sensors in order to calculate the distance moved and how long is left The boost library is used for this Continuing the static variables from where the x and y variables are
62. ly de scribes all the software and tools used during the project Chapter 3 outlines the design and procedure for each technology The interconnection is struc tured in a Client Server approach Chapter 4 discusses weaknesses and improvements for the independent areas Usage areas are covered and the questions will be answered Chapter 5 summarizes the project constitutes the problems that occurred and gives an evalua tion 1 5 Contribution During the thesis the work load has not been completely divided The main focus for Daniel was the Mica motes the MULLE and Ekahau while Sebastian worked on the robot However the work has overlapped and both of the authors have been involved in each step of the develop ment process Chapter 2 Background This section describes the different technologies in order to give a more in depth view of what they and their capabilities are 2 1 Scorpion robot The Scorpion robot is maintained by Evolution Robotics and is equipped with the following features 13 10 IR range finder sensors Contact sensing bumper mounted in front of the robot A Robot Control Module The module provides motion control auxiliary digital and analog I O capabilities and sensor I O Wide angle calibrated video camera with precision tilt adjustment Servo powered differential drive Rechargeable 12V battery and charger USB interface Cushioned cradle for laptop computer The Scorpion robot can b
63. method and needs to be included in the C source file For the Move example it might look something like this DO NOT EDIT THIS FILE it is machine generated x include lt jni h gt x Header for class src_Scorpion_Navigation_Move x ifndef _Included_src_Scorpion_Navigation_Move define _Included_src_Scorpion_Navigation_Move ifdef __cplusplus extern C endif Class src_Scorpion_Navigation_Move Method startUpMove x Signature I V JNIEXPORT void JNICALL Java_src_Scorpion_Navigation_Move_startUpMove JNIEnv jobject jint ifdef _ cplusplus endif endif 4 The C implementation of the native method must be written Again for the Move exam ple include src_Scorpion_Navigation_Move h p g JNIEXPORT void JNICALL Java_src_Scorpion_Navigation_Move_startUpMove JNIEnv x env jobject jobj jint updateFreqMicroSec C code goes her 5 To create a native library the C implementation needs to be compiled Under Linux this can be done by the following command g c o Move o Wall Move cpp There might be a need to add arguments to g about where to find the java header files and java Linux header files The above command will create an object that needs to be linked as a shared library which can be done with gcc gcc shared levobas levotask o libMove so Move o In this case some ERSP libraries needed to be linked with the shared librar
64. method that is used extensively is the doExplore method Before this method is run the initializeGrid should be run in order to set up the OccupancyGrid which is used by the ExplorationGrid There are some global variables and pointers defined in the Exploration cpp file that needs to be mentioned ExplorationGrid eg NULL OccupancyGrid grid NULL GridPointList path bool isRunning false As for doExplore it takes a start and goal position in form of x and y coordinates and re turns an array of integers The array will contain the pixel positions in the map of where the robot can move First in doExplore some variables are declared Then the eg pointer is instantiated using the global grid pointer The method find_shortest_path is then used on the supplied arguments and the result is stored in the path list JNIEXPORT jintArray JNICALL Java_src_Scorpion_Navigation_Exploration_doExplore JNI Env env jobject jobj jint start_x jint start_y jint goal_x jint goal_y int y 0 jintArray jArray jclass cls nv gt GetObjectClass jobj jfieldID startxID nv gt GetFieldID cls startX I jfieldID startyID nv gt GetFieldID cls startY I bool firs true T h eg new ExplorationGrid grid ss bool succe Ifa eg gt find_shortest_path start_x start_y goal_x
65. nd when the robot is within such an area data will be read from the sensors that have been placed at these areas The stipulated technologies are all working together but more effort could have been made in trying to integrate more of the features of each technology Without time as a constraint a try to achieve the following would have been done 4 Discussion 36 e Obstacle avoidance for the robot working with both IR sensors and object recognition e A more path reducing method for the navigation for example turning and moving at the same time e Some form of streaming methodology for the camera instead of sending pictures e Speech interaction to give commands to the robot e Object recognition to recognize sensors e Making the source code secure fail safe efficient and easy to understand 4 10 2 Is the robot self controlled It is in some sense Getting from start to goal is all done by the code for the robot However the robot does not avoid obstacles at the moment so manual interaction might be needed and Ekahau is not reliable enough to provide a current position for the robot 4 10 3 Alternatives to Java The programming language used for each technology are the following ERSP C TinyOS nesC Mule C Ekahau Java or YAX As with the ERSP it would have been easier to use the C API directly then to use JNI However using C strictly for the whole project would have aggravated the process of creating networ
66. ntField cls nw_sensor_id int distance usleep 500000 The IRSensor class is instantiatied as a static variable in the Move class and in Move the meth ods for avoiding obstacles are implemented as described in Appendix B Appendix E Communicating with Ekahau Firstly ensure that an instance of EPE is running on the computer that the application should connect to Then call the connect method of the PositioningEngine class to establish a connection to the desired positioning engine PositioningEngine connect 127 0 0 1 Once connected to the positioning engine the API is ready for use call the getDevices method to receive all trackable devices Map devices PositioningEngine getDevices Before looping through all devices a LinkedList and a Handler is created to store all tracked devices and handle their input List trackedDevices new LinkedList Handler handler new Handler In the sequel for loop an Iterator is used to go through all the devices in the Map and creates a TrackedDevice instance which represents a physical wireless device for every one The TrackedDevice class is the base class for Ekahau Positioning functionality Firstly it is used to set various tracking options via its set TrackingParameters method in this case the num ber of logical area that should be received Secondly it registers listeners that receive information about where the wireless device is
67. nverter was needed otherwise the MULLE would risk being perished 4 2 Enhancements for Scorpion ER1 and ERSP 4 2 1 A smallar robotic device Since the physical size of both the Scorpion and ER1 robot are designed to fit a laptop this will limit access to small locations and the need for obstacle avoidance will be greater Combining a smaller size of the robot with possibilities to use built in applications would certainly enhance the robots passability 4 2 2 Environment insensitivity Throughout this project the surrounding environment has consisted of an office space This area is neither wet humid heavy trafficked nor very narrow and the probability for the robot to work correctly under such circumstances is small As a result the number of usage areas will be limited 4 2 3 Improve the ERSP API In the ERSP API there are some incomplete classes and methods Some of these classes and methods would have been useful at certain times There was also some problems with the API when using the MoveTo task and when using the HAL to get an image from the camera Tracing the system calls it was shown that the problem lied within thread scheduling in the Linux kernel and the identified cause was the Java Native Interface Furthermore some changes were done to one header file in the API to make it compile cleanly 4 2 4 Add laser sensors The IR sensors are not updated fast and accurate enough hardware based to allow good avoid ance o
68. ocation xPosition int accurate getX yPosition int accurate getY LocationContext lc accurate getLocationContext mapScale lc getMapScale The logical area handler is called with two arguments where one is an array that holds the logical areas area From this variable it is possible to extract useful information such as the logical areas name and with which probability the device is located within that specific area String logicalArea areas i getName LogicalArea area areaslil Double probability area getProbability 100 Ultimately status messages are received in the status handler The handler receives both the tracked device and its belonging status message Here the status message is just printed to the standard output with the IP address of the tracked device String ipAddress String device getAttribute IPADDRESS System out println Status for device ipAddress status Appendix F Installing a TinyOS application The syntax for compiling an application in Cygwin is of the form make lt platform gt Since MICA2 processor radio platforms MPR410 are used the syntax should be make mica2 This will compile the application that is located in your current working directory However this does not install the compiled application into a mote There are two commands for executing the installation install and reinstall The difference is that the latter only downloads
69. oleanField cls readyid readyValue delete context The same thing is then done for a change in the y value But the angle to turn to either 90 or 90 degrees is needed After this the xold and yold variables are set to the x and y variables correspondingly Then a usleep 100000 is used so that a unnecessary use of resources are not done xold x yold y usleep 100000 In Move java there is an instance of the IRSensor class since this is the only place where it can interfere with any movement Furthermore there are two methods breakFree and breakFreeLight implemented in Move java None of them are working fully The method breakFreeLight reads the sensors on the side of the robot and if the values obtained from these sensors are lower than a specified value a small turn in the other direction is done How ever this method is not completed and the robot can get stuck private void breakFreeLight boolean sensorNE sensor_ne lt NE_VAL boolean sensorNw sensor_nw lt NW_VAL r if sensorNE amp amp sensorNW if sensor_ne lt sensor_nw setAngle 10 else setAngle 10 e else if sensorN setAngle 10 yet else if sensorNW setAngle 10 Appendix C Exploration and FindPath classes The the Exploration class contains native methods for accessing the OccupancyGrid class and ExplorationGrid class One native
70. ould be heard at any location and if possible placed in the corners of the intended coverage area The positioning engine works with just one access point but will have inferior accuracy If less than three access points are audible the average error will exceed five meters Increasing the number of overlapping access point signals generates a higher veracity with three or more audible access points an average accuracy of one meter can be achieved The competing tracking systems require additional network hardware overlay which cost time and resources Due to varying hardware and software used by WLAN card manufactures the radio recep tion can differ significantly This can cause positioning inaccuracy if the tracked devices use another WLAN adapter than the positioning model was configured for Without using any mit igation technology the typical positioning inaccuracy caused by different cards is 1 4 meters depending on the network card The Ekahau Manager uses a system called Ekahau Card Models to read information about the network cards and mitigate the Received Signal Strength Intensity RSSI measurement differences EPE is capable of tracking thousands of devices simultaneously even if they are in different buildings Information about the tracked device includes e X and Y coordinates e Building e Floor level e Logical area created by user e Heading e Time e Speed There are two ways to connect to the engine and
71. plications The rich client platform that forms the basis for Eclipse contains the following components e Acore platform to boot Eclipse and load plugins e Framework that follows the Open Services Gateway initiative OSGi 2 Background 19 El 0 oure g IP 192 169 0 1 ORT 5063 E Ce l Figure 2 10 The Eclipse framework e JFace for handling text and file buffers e Eclipse Workbench that contains editors wizards views and more See figure 2 10 for a screenshot of the Eclipse application 2 6 3 TinyOS In a wireless sensor network where the motes have severe memory constraints the necessity of a suitable operating system is high TinyOS 30 is an open source operating system designed for sensors with diminutive hardware Its component based architecture minimizes program size while enabling rapid innovation and implementation TinyOS has an event driven execution model that enables exhaustive power management while providing scheduling flexibility There are two threads of execution Tasks Functions whose execution is postponed until they are scheduled Tasks run to comple tion and do not preempt each other Hardware event handlers Executed as a reaction to a hardware interrupt like a task it runs to completion However it may preempt the execution of a task or other hardware event handler The TinyOS system libraries and applications are written in nesC 25
72. read is set to 0 and a Boolean value that indicates that we are done with the moving is set to true Contexts are deleted to get memory allocation back TaskArg args2 distance linear_velocity TaskArg args3 angle 90 context TaskContext task_args 2 args2 context2 TaskContext task_args 2 args3 turnrelative gt run context2 timer t0 movedelta gt run context double timerTime t0 elapsed env gt SetStaticDoubleField cls xid 0 0 env gt SetStaticDoubleField cls yid 0 0 env gt SetStaticBooleanField cls readyid readyValue delete context delete context2 Next the same procedure is done but now when only the x value has changed However the difference is that here there is a try to use pthreads in order to get the thread id and to kill the thread when an obstacle is found by the IR sensors This is not finished due to time constrains else if x xold 88 y yold amp amp x 0 TaskArg args x linear_velocity context TaskContext task_args 2 args int rey ts void status pthread_t thread pthread_attr_t attr pthread_attr_init amp attr timer t0 movedelta gt run context pthread_create amp thread amp attr ThreadRun void x t pthread_attr_destroy amp attr rc pthread_join thread amp status double timerTime t0 elapsed_min env gt SetStaticDoubleField cls xid 0 0 env gt SetStaticBo
73. recognize the presence of a person and follow that person s movement This can also be done with an ordinary object The motion flow module works by computing the motion between two images on a block by block basis with a customizable block size By computing the cross correlation of pixel bright ness with the first image with all the blocks of the second image the algorithm can estimate the flow for each block with pixel accuracy A Gaussian mixture model 31 is used to represent the color that is to be trained The color is represented in HSV 32 color space since it is more stable to illumination brightness levels than RGB Navigation modules are made up by mapping localization exploration path planning ob stacle avoidance occupancy grid mapping target following and tele operation control 14 Mapping and localization The visual Simultaneous Localization and Mapping vSLAM algo rithm is the core of Navigation It works in four steps In the first step it traverses the area collects odometry and acquires an image Next the image is processed to extract visual features Step three consists of three parts and is dependent on if the number of visual features is large and distinct enough Part a of step three determines if the features correspond to a stored landmark A land mark is a collection of unique features that are extracted from an image 14 If the landmark is stored the algorithm continues to part b otherwise
74. retrieve the information either through a Java API or by making use of the Ekahau Yax protocol The latter is a character based Transmission Control Protocol TCP and can be used from any programming language that supports TCP sockets It is recommended to use the Ekahau Software Development Kit SDK if the develop ment environment supports Java 1 4 1 seeing that it is the easiest way to implement a location aware application 2 4 1 Ekahau manager Ekahau Manager is an application that is used to create manage and store a positioning model in the positioning engine This positioning model requires a map over the building in one of the supported formats BMP JPG or PNG Some functions provided by EPE also needs a correct map scale to calculate impeccable answers 2 Background 14 Audible access points might belong to another company or a private resident therefore it is important to restrict the access points that should be used Otherwise the model might easily become erroneous if an access point is moved or taken down The positioning model requires the user to draw Tracking Rails on the map indicating pos sible travel paths for the tracked object EPE also needs a calibration to pinpoint Wi Fi enabled devices This is done by recording sample points with the manager laptop Sample points should be recorded e Every 3 5 meters e Inall Tracking Rail intersections e Start and End position of Tracking Rail e Where the radio env
75. ril 24 2006 18 Sheng Liang The Java Native Interface Programmer s guide and specification Addison Wesley http java sun com docs books jni download jni pdf 1 edition 1999 Address valid as of April 13 2006 19 lwbt homepage http www sm luth se conny Iwbt Address valid as of April 4 2006 20 Iwbt a lightweight bluetooth stack for lwip Address valid as of April 4 2006 38 21 lwip homepage http savannah nongnu org projects Iwip Address valid as of April 4 2006 22 M16c flasher homepage http m16c cco ev de M16C Flasher 19 0 html Address valid as of April 12 2006 23 MULLE homepage http www ltu se web pub jsp polopoly jsp d 4111 ra 14037 Address valid as of April 4 2006 24 LM61 Temperature Sensor datasheet http www national com ds cgi LM LM61 pdf Address valid as of April 4 2006 25 nesc homepage http nescc sourceforge net Address valid as of April 4 2006 26 Scott Oaks Java threads O Reilly 3 edition 2004 27 J2SE 1 5 0 API http java sun com j2se 1 5 0 docs api Address valid as of April 4 2006 28 The Java Tutorial http java sun com docs books tutorial index html Address valid as of April 4 2006 29 Nat homepage http www sm luth se conny nat Address valid as of April 4 2006 30 Tinyos homepage http www tinyos net Address valid as of April 4 2006 31 Gaussian mixture model description http en wikipedia org w
76. terpreter in form of the behave application which instantiates and runs behavior networks Task Execution Layer The Task Execution Layer TEL is a high level task oriented interface to the Behavior Execu tion Layer A flexible plan to be executed by the robot can be created by combining tasks and sequence them using functional composition TEL is by so a way to express higher level execu tion knowledge and coordinate the actions of multiple behavior Advantages with the TEL is familiarity defining tasks is comparable to writing standard C functions and ease of scripting including languages like Python Due to copyright and restricted access exact details about the classes and types that make up the TEL can not be given What can be mentioned is that they are divided into these resembling parts e Code that runs when a task is executed A registry for keeping track of tasks and indeces them A way of handling arguments to tasks Information about task status Return values from tasks A way of handling asynchronous tasks and supply a solution for how tasks communicate with each other e Running multiple tasks simultaneously Core technologies Navigation and Vision are two technologies that are more significant Vision is divided into two parts object recognition in form of ViPR Visual Pattern Recog nition and image processing The system for object recognition focuses on recognizing planar textured objects Obje
77. the thesis is to obtain a self controlled robotic device that reads information from sensors stores the information moves to the base area and uploads the information to a client Acknowledgments The master thesis was performed at Monash University in Melbourne and began in November 2005 and ended in April 2006 Jointly we would like to thank our prominent supervisor Arkady Zaslavsky at Monash Uni versity Without him this project would not been possible Furthermore we are especially grateful to Kare Synnes our examiner at Lule University of Technology for his exceeding help with organizing everything in Lulea and introducing us to Arkady Many thanks also goes to Shonali Krishnaswamy our cooperative supervisor at Monash Uni versity for her insightful opinions and Paul Hii technical advisor at Monash University for his efforts supplying us with any technical equipment needed One must also appreciate the help from Michelle Ketchen School Manager at the Faculty of Information Technology at Monash University Inger Niska Ekblom and Christina Hamsch at the International Office at Lule University of Technology And finally thanks to Jens Eliasson for his help with the MULLE Melbourne 20 April 2006 Cook Islands 7 May 2006 Dantel Larsson and Sebastian Sj din List of Figures Evolution Robotics Scorpion robot s ss s es ee 9 Evolution Robotics ERL robot 6 ee 9 Ekahau Manger displaying network coverag
78. ureSize pictureSize jpgReceiver read else if object instanceof SensorPacket SensorPacket sensorPacket SensorPacket object double temperature sensorPacket getTemperature TempLabelPanel setTemp temperature for int i 0 i lt temperature length i if temperature i lt 20 amp amp temperature i gt 0 logger warning name i temp low formatter format temperature i degrees Celsius lse if temperature i gt 25 logger warning name i temp high formatter format temperature i degrees Celsius public static void send Object packet sendLock lock if isConnected try outStream reset outStream writeObject packet catch IOException e e printStackTrace sendLock unlock
79. us appears an alarm could be triggered and the robot will try to move to the area where the alarm was set off However since the Bluetooth version currently on the MULLE has a limited range of ten meters only a small area can be covered A newer version of Bluetooth on the MULLE would allow a greater area With the help of the positioning system the robotic device can also superintend the movement and location of all individuals and material that carries a Wi Fi tag The Wi Fi tag is also equipped with a panic button that works as an assault alarm and sends the location to the robot Additionally the MICA motes can gauge the intensity of the light and listen after sounds 4 8 Is there a need for extensive analysis of compatibility In today s information technology society when the seemingly escalating number of software applications takes the software developing market into a highly competetive level the need for a product with well analyzed compatibility is almost indisputable Failing in this aspect results in fewer users and by so testers This adds up to lesser usage areas and lesser improvements Good and useful feedback is important for every product and its developers 4 Discussion 35 What is meant by compatibility Compatibility in this context when combining different technologies means in our sense e Degree of operating system independence e Flexibility of SDK is the programming language of choice limiting what can be ach
80. y It should be noted that the path to 1ibMove so needs to be in the LD_LIBRARY_PATH environment variable in order for Java to find it 6 To run the application use the java runtime interpreter Both the Move class and the libMove so native library will be loaded at runtime Appendix B Move class Since most of the navigation is handled by the native method startUpMove found in the Move java class this appendix will concentrate on describing this method This method will run until it is stopped so a while loop is used The first thing that happens in this loop is that static variables in the Move java class file will be read while isRunning linear_velocity env gt GetStaticDoubleField cls lvid x env gt GetStaticDoubleField cls xid y env gt GetStaticDoubleField cls yid readangle env gt GetStaticIntField cls aid When this is done a check for a value not equal to zero for the readangle is made If that is the case the arguments for the task TurnRelative are set and then the task is run The value of the static variable where readangle got its value is set to 0 to allow new values Sure this can mean that values set in the static variable might be skipped if readangle 0 TaskArg argen readangle 90 context2 TaskContext task_args 2 argen turnrelative gt run context2 env gt SetStaticIntField cls aid 0 delete context2 Next step is to

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