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XIAOYUN DENG ROBOT WORKCELL MODELLING AND

1. esses 38 Figure 23 Trajectory of robot and coordinate range of obstacle s bounding box plot LIST OF TABLES Table 1 A list of different collision detection software VI VII LIST OF ALGORITHMS Algorithm 1 Create 3D objects in MATLAB ceres ea Ee EE ERR 14 Algorithm 2 Create sphere in MATLAB essere o severe entree Y eor S rin UR G 15 Algorithm 3 Create robot in MATLAB ssssssesssreereeresresesssssssssesseeeee 16 Algorithm 4 Model of collision detection interface eceee eee e eee neces 18 Algorithm 5 Real time collision detection ce sees eee ene eeneeeeneeeaenees 19 Algorithm 6 Collision detection interface cesses 21 Algorithm 7 Collision detection by comparing coordinates for cube shape ODJECIS sous eek ended 23 Algorithm 8 Collision detection by calculating distance for cube shape objects 24 Algorithm 9 Collision detection by comparing distance for sphere shape vi En 25 Algorithm 10 Trajectory planning for collision detection suus 27 LIST OF CODE Code 1 Define and model the robot sss 30 Code 2 Voxel function for making the robot workcell c cece eee eee ence eee eees 31 Code 3 Collision detection for rough model of workcell ssussuss 3D Code 4 General function for collision detection ccc cece ence ence ee eee eee eneees 34 Code 5 Collision detection
2. A Fast Produce for Computing the Distance Between Complex Objects in Three Dimensional Space IEEE Journal of Robotics and Automation April 1988 Gilbert E G Hong S M A new algorithm for detecting the collision of moving objects Proceedings of the IEEE Interna tional Conference on Robotics and Automation Scottsdale May 1989 Hollars M G Rosenthal D E Sherman M A SD FAST User s Manual Symbolic Dynamics Inc USA 1994 Jimenez P Thomas F Torras C 3D Collision Detection A Survey Institut de Rob tica i Inform tica industrial Barce lona Spain 2000 Joel S Voxel function MATLAB Central file exchange Kazi 2002 Lin 1993 Lin 1996 Liu 2010 Luca 2006 MATHWORKS MERL 1997 Microsoft 2012 Moore 1988 PRODEMO Reichenbach 2003 45 2003 Kazi A Merk G Technical Report Experience with Re alSim for Robot Applications KUKA Roboter GmbH Augs burg Germany 2002 Lin M C Efficient Collision Detection for Animation and Robotics University of California Berkeley 1993 Lin M C Manocha D Cohen J Collision Detection Algo rithms and Applications University of North Carolina Chap el Hill USA 1996 Liu H Ding H Xiong Z Zhu X Intelligent Robotics and Applications Third International Conference ICIRA 2010 Shanghai China 2010 Luca A Albu Sch ffer A Haddadin S Hirzinger G Colli sio
3. plot rob qInput a 700 sf i 3 0 standarg ly etendard l standard 0 standard r 0 1885 0 75398 14 compute the robot end effector s coordinates 1 T 1 4 2 T 2 4 3 T 3 4 conveyor green voxel 700 700 900 voxel 700 700 830 Sconveyor black voxel 700 470 900 voxel 700 470 830 sconveyor hold part voxel 500 700 900 voxel 400 700 900 voxel 300 700 900 voxel 400 700 900 frame voxel 700 700 900 Stop voxel 700 700 1500 Supper part buttom lay voxel 700 700 930 Smiddle layer voxel 700 700 900 voxel 700 700 450 sbase voxel 500 400 1650 Slines line 15 15 700 line 15 15 700 70 line 700 700 15 line 700 700 15 line 700 700 15 1 line 700 700 15 15 line 15 15 700 70 line 15 15 700 700 cube voxel 700 700 930 rl 15 fkine rob qInput 1400 70 70 0 5 0 5 0 5 1 0 1400 70 30 0 0 0 6 0 2 1 0 1400 70 70 0 5 04 5 0 5 0 9 3 1400 70 30 0 0 0 0 0 0 1 0 100 300 100 0 5 0 5 0 5 0 9 100 300 100 0 5 0 5 0 5 0 9 100 300 100 0 5 0 5 0 5 0 9 100 300 100 0 0 5 0 5 0 9 5 1400 1400 2450 0 7 0 7 0 7 0 2 1400 1400 30 0 9 0 9 0 9 0 0 er 1400 1400 30 0 7 0 7 0 7 0 2 1400 1400 450
4. 0 7 0 7 0 7 0 0 1400 1400 30 0 7 0 7 0 7 0 0 1000 1050 720 0 9 0 9 0 9 1 0 700 420 1500 tooclor PM uL Oj 420 1500 color PY 15 420 1500 dais p 420 1500 color ys 534 2420 1500 golber de Ja 42 0715001 Elor RT 0 r 420 1500 y ee Eo see 7420 1500 color XEk 200 200 200 0 0 0 6 0 2 1 0 drive this graphical robot by means of a slider panel drivebot rob 53 APPENDIX 3 MATLAB CODE FOR TRJECTORY PLANNING AP PROACH FOR COLLISION DETECTION 350 0 50 0 ll x 2500 0 0 ll e x La H gt wN qinput 1 rob TO trans1 373 528 T1 trans1 86 826 eS ho r j TC ctraj TO T1 r Figure 3 plot t 00 720 1 0 0 300 0 robot 11 12 13 14 466 237 558 839 0 0 2053 10 traj 0 1 t transl TC ld on standard standard standard standard 350 188 347 130 L 885 0 062832 0 1885 0 75398 50 50 50 50 50 50 q t plot 0123456789 10 t q eolor nm hold on q t plot ho q t plot 150 150 150 150 150 150 012345678 9 10 ty molor m ld on 500 500 500 500 500 500 01234567 8 9 10 GC dq seller y hold on q t plot ho 700 700 700 700 700 700 01234567 8 9 10 t gq eolor y ld on 50 50 50 150 150 150 500 500 500 700 700 7
5. Australian Robot Association Melbourne Australia July 1995 Corke P L A Robotics Toolbox for MATLAB IEEE Ro botics and Automation Magazine Volume 3 March 1996 pp 24 32 Corke P I Robotics Toolbox for MATLAB Instructions 2008 Corke P L Robotics Vision amp Control Springer 2011 ISBN 978 3 642 20143 1 Craig 2004 Ehmann 2000 Ericson 2004 Ericson 2005 Fawaz 2009 Fischer 2009 Gilbert 1988 Gilbert 1989 Hollars 1994 Jimenez 2000 Joel 2003 44 Craig J J Introduction to Robotics Mechanics and Control Third Edition Prentice Hall 2004 ISBN 0201543613 Ehmann S SWIFT Speedy Walking via Improved Feature Testing http gamma cs unc edu SWIFT Accessed May 2012 Ericson C The Gilbert Johnson Keerthi GJK Algorithm The 31st International Conference on Computer Graphics and Interactive Techniques Los Angeles California USA 2004 Ericson C Real time Collision Detection Elsevier 2005 ISBN 978 1558607323 Fawaz K Merzouki R Ould Bouamama B Model Based Real Time Monitoring for Collision Detection of an Industrial Robot Ecole Polytechnique de Lille France 2009 Fischer M Henrich D 3D Collision Detection for Industrial Robots and Unknown Obstacles Using Multiple Depth Imag es Lehrstuhl f r Angewandte Informatik III Universitat Bayreuth Germany 2009 Gilbert E G Johnson D W Keerthi S S
6. Services DSS it allows the orchestration of numerous services to make complicate behaviours The features are a visual programming tool Microsoft Visual Programming Language for making and fixing robot applications interfaces which based on web and windows 3D simulation including hardware acceleration easy ac cess to a sensors and actuators of the robot The main programming language is Mi crosoft Visual C Sharp Microsoft 2012 One of the approaches to detect collision in the Microsoft Robotics Developer Studio for a mobile robot is to install a laser device which can measure the distance From the hardware which Microsoft provided the robot has two contact sensors in front and back and a 180 degree SICK Laser Range Finder LRF device SICK 2008 The colli sion detection performed like the robot first scan the whole environment find the big gest open space and then choose one direction within this range to move In the situa tion if robot hit obstacle accidentally the robot will stop and move back Microsoft 2012 Figure 5 Robot scan with laser range finder LRF Microsoft 2012 2 2 3 Collision detection in CIROS Studio CIROS Studio is a professional tool for building and simulating complicated workcell models It s a software package that can easily be used for factory workflow and im proves the communication between all involved sections and operators CIROS Studio is modular software which can be adjusted for the cu
7. and the command line is the main function used The workcell contains conveyors cube shape objects sphere shape ob jects the conveyors can be formed by several cuboids An example of a basic model conveyor is shown in the picture below 1000 1000 1000 Figure 18 A basic conveyor model After creating the conveyor next task is to build the entire workcell for robot The en tire workcell is made by the same approach as creating the conveyors constructed by lines and cube shape objects the picture of the workcell is shown in the figure 20 4 IMPLEMENTATION 37 500 S 1000 1500 A Figure 19 Model of workcell 4 9 The graphical user interface for collision detection In the process of developing the graphical user interface several versions of user inter faces have been made All of them are presented in this section from the initial simple ones to the final version one the complete MATLAB code for this part can be found in the appendix of this thesis In the beginning of user interface development a simple interface is made with the very basic collision detection function It is for more convenient to show the result of colli sion between robot and workcell The process of making this GUI mainly followed the guide of MATHWORKS company website product help pages First give the joint posi tions values into the input text box push the button in the middle and then can get the result from the output edit box The ini
8. approaches are spa tio temporal intersection swept volume interference multiple interference detection trajectory parameterization Gilbert Johnson Keerthi GJK algorithm From a survey of previous research work one of the most used algorithms is the GJK algorithm GJK algorithm is an original test for collision between two objects After the five collision detection approaches are introduced an overview of the collision detection methods used in current industrial robots is presented Several commercial simulation tools which contain collision detection function are introduced for example the collision detection function in ABB robots Microsoft Robotics Developer Studio CIROS Studio And then another two approaches developed for current industry robots are described The purpose of introducing different modelling tools is for comparing them so that people will have a general view about these tools 2 1 Robot collision detection It is a long history of collision detection and determining the minimum distance related problems Many collision detection algorithms have been developed in the fields of computational geometry robotics and computer graphics in recent years Collision de tection includes the static and dynamic situation of objects and robot in the environ ment The common problem often stated as for a set of objects and with the details of their motions in a certain time period to see if there is two of them will come into
9. code for robot and sphere shape objects 34 Code 6 Detect collision in real time VIII LIST OF ABBREVIATIONS 3D 4D ARR CCR CIROS CSG DH DSS FDI GUI GJK LRF MRDS PLC OBB RAPID SOLID SWIFT Three dimensional Space Four dimensional Space Analytical Redundancy Relation Concurrency and Coordination Runtime Computer Integrated Robot Simulation Constructive Solid Geometry Modelling Denavit Hartenberg Decentralized Software Services Fault Detection and Isolation Graphical User Interface Gilbert Johnson Keerthi Laser Range Finder Microsoft Robotics Developer Studio Programmable Logic Controller Oriented Bounding Boxes Robust and Accurate Polygon Interference Detection Software Library for Interference Detection Speedy Walking via Improved Feature Testing 1 INTRODUCTION With the manufacturing industry development more and more industry robots are used in the factories By the aid of computer systems it allows user to analyse simulate and verify the working process of robot machines and the entire production line For get ting the precise result of analysing the manufacturing system it requires suitable algo rithms This thesis work focus on the robot workcell modelling and robot collision de tection problems The working envelope of robot is restricted by its kinematic character istics and links geometry Beside this the environment of the robot wor
10. detection for cube and sphere shape objects in the workcell is for the robot work safety to reduce the possibility of robot harm human in the operation and envi ronment damage 5 CONCLUSION 42 About the collision detection algorithm developed in this thesis work it contains two approaches one is by comparing the boundary coordinates of the objects in the workcell and the coordinates of the robot end effector if the robot end effector s coordinates within the boundary of the object then collision occurred Another approach is to calcu late the distance between robot end effector and any point of the object if there is dis tance between one point in the object and the robot end effector that is less than a threshold value this value can be set by the system operator then collision occurred Finding an approach for modelling robot and workcell components making a tool for collision detection are the two main goals of this thesis both of them are reached This thesis provided a way to detect collision in robotics workcell in the MATLAB environ ment and also the modelling work can be used for further development For the future work there is some things can be improved for example it can increase the robot s re action performance might be using knowledge of artificial intelligence to the robot and workcell so that robot can predict the collision before it actually happens then it can avoid collision situation The cell also can be u
11. eventdata handles 51 after setting all properties after setting all properties Executes during object creation after setting all properties function Result edit CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end Executes on button press in pushbutton9 function pushbutton9_Callback hObject eventdata handles if str2double get handles StartX_edit String lt 200 2122 amp amp 200 2122 lt str2double get handles StartX_edit String str2double get handles SizeX_edit String amp amp str2double get handles StartY_edit String lt 565 3050 amp amp 565 3050 lt str2double get handles StartY_edit String str2double get handles SizeY_edit String amp amp str2double get handles StartZ_edit String lt 350 1885 amp amp 350 1885 lt str2double get handles StartY_edit String str2double get handles SizeY_edit String result Collision else result No Collision end set handles Result_edit string result guidata hObject handles 52 APPENDIX 2 MATLAB CODE FOR MODELLING WORKCELL Sbuild the robot 1 link 0 350 0 50 12 link 0 250 0 0 0 13 link 0 0 0 720 14 link 0 0 0 300 gInput 1 885 0 062832 rob robot 11 12 13 figure 1
12. for controlling the robot links and then the user can see if the robot has collision with other object There are difficulties for capturing the real time output values of the robot end effectors coordinates in the end it solved by place the collision detection code in the place before the else statement in the m file of the drivebot function In the picture below q is the value of joint coordinates For the initial value of q user can give this set of value or this value can be obtained from the joint coordinates of the graphical robot By running drivebot m file it contains the function of detecting collision in real time This function realized by modifying the drivebot m file in MATLAB The usage of the drivebot m file is for driving a graphical robot by means of slider panel Corke 2008 This modify ing made it is possible when user moves the links of the graphical robot the collision 4 IMPLEMENTATION 36 result of robot and the objects around robot will be shown in the GUI The red circle of the picture below is the collision detection function has been added to the original GUI this is the place where user can see the result of collision by moving the sliders Ee Cees ef 0 062832 e 0 1285 Figure 17 A real time collision detection user interface 4 8 Model the robot workcell After getting familiar with the 3D drawing in MATLAB the real robot workcell for Sony SRX 611 robot is modelled The function voxel
13. measured about X4 a is the distance from Z4 to Z measured along X4 theta is the angle between Xy and X4 measured about Z d is the distance from Xy to X4 measured along Z4 The parameter selected here is based on the size of real Sony SRX 611 robot The fifth line in the code is a set of values for the initial position for each links The sixth line of the code is using robot command to build graphical robot The 4 IMPLEMENTATION 31 seventh and eighth lines in the code are for making a picture and plotting the robot in a separate window The last line of this code is for manipulating the links of this robot The robot is built in MATLAB after executing the code above a picture of this graph ical robot is shown in the figure 14 Figure 14 A Sony SRX 611 robot model in MATLAB 4 3 Rough model of the robot workcell At the beginning of modelling the entire robot workcell it started from building a sim ple cube which robot is located in it There are different ways to build a 3D cube in MATLAB environment in this thesis a MATLAB function named voxel is used Voxel is a simple function to draw a voxel cube cuboids in a specific position of specific dimensions in a 3 D plot Transparency of the voxel can also be defined Many voxels can be arranged to construct new shapes The voxel command and the dimension and the location of the cube is defined here the command for building the workcell is Code 2 Voxel function for making the
14. object the result is shown in the same interface The main algorithm for this approach is presented below Algorithm 5 Real time collision detection Name Real time collision detection Description This algorithm is made for detecting collision in real time when user moves the slider in the interface at the same time in the right upper part of the interface it will show if there is collision occurred Steps 1 function name is drivebot 2 give value for the back ground colour 3 if input a is character array 4 set a name of robot 5 set b joint index 6 set q as initial position of robot 7 for robot and initial position q 8 if the input array q is empty 9 then q zeros 10 end 11 then get value from slider 12 or get value from text box 13 plot robot with the initial position q 14 end 15 get forward kinematics for each joint space t6 16 compute the coordinates of the cube which located near the 3 APPROACH 20 robot 17 compute the minimum and maximum values for the cube coordinates in x axis Xmin and Xmax in y axis Ymin and Ymax in z axis Zmin and Zmax 18 if the end effector s coordinates t6 within the cubes coor dinates Xmin Xmax Ymin Ymax Zmin Zmax 19 display collision 20 else 21 display no collision 22 end 23 else 24 create th
15. presented Chapter 2 is a survey of the most advanced techniques which are developed in the field of robotics collision detection In this chap ter the most common approaches and collision detection tools are presented Chapter 3 is a detailed description of the approaches and algorithms In this chapter the approaches are introduced in the sequence of build 3D objects build the workcell frame for the robot build the robot make graphical user interface for controlling the robot in MATLAB develop the user interface so that it can detect collision between robot and objects in the surrounding environment in the end of this chapter the collision detection algorithms is specified Chapter 4 is the implementation based on the approaches ex pounded in the chapter 3 In chapter 4 the result of creating of 3D objects working cell robot and graphical user interfaces is showed Chapter 5 is a conclusion of this thesis it s a summary of the approaches which has been developed for avoiding collision in the robot working cell 2 STATE OF ART In this section the state of art of robot collision detection and robotics modelling by MATLAB is discussed For getting to know the most advanced technique in the robot ics modelling robotics collision detection field many research publications have been reviewed the most significant ones are presented At the beginning of this chapter is an introduction of five main approaches of collision detection These
16. q the constraints are qi to qo 4 qi t di 5 Where t is the starting time tris the ending time qg and q are the specified initial position and velocity q and q are the specified initial position and velocity The cubic polynomial for joint position and its derivative for joint velocity are shown below qi t ag a t a t a t 6 d t a 2azt 3a3t 7 Where the position value q is the degree of the joint in this thesis the collision point will be focused so using the joint space method is not very suitable for catch the colli sion points Here Cartesian space method will be used to find the collision point be cause it can track the coordinates of points in the trajectory Once these points are known to the robot it can avoid collision Craig 2004 For current used collision free trajectory planning approaches most of them have mod els of manipulator the work area and all the obstacles in the area When the user de fines the desired goal point of the manipulator motion and let the system determine which route to go so that the goal is reached without the manipulator hitting any obsta cles The approach used in this thesis is to build both models of the robot and the obstacles the obstacles can be different shapes but here a cube shape model is made for them all even if the obstacle is a sphere we assume it is in a cube shape bounding box By using the robotics toolbox in MATLAB the Cartesian tr
17. robot workcell Voxel 700 700 1750 1400 1400 2450 0 2 0 0 0 8 0 2 In this line of code the first set of three values are the starting point of the cube shape frame these three values represent the start point value in x y z axes in millimetre The second set of value means the size of this cube shape frame in x y z axes The third set of value means the colour of this cube the last value of this code is the value of trans parency the value range is from 0 to 1 0 means transparent while 1 represents opaque The picture of robot and its working cell rough model is 4 IMPLEMENTATION 32 X Figure 15 A rough model of robot and workcell 4 4 Collision detection for rough model of robot workcell After the workcell model is built the next step is to detect collision between this cell and the robot The approach used for detecting collision between robot and the working cell is by comparing the coordinates of the robot end effector and the coordinates of the workcell cube if the x axis coordinate of robot end effector is greater than the maxi mum x axis coordinate of the cube or less than the minimum x axis coordinate of the cube and apply this rule also to the y axis and z axis then the robot and cell have colli sion Otherwise the robot and workcell cube do not have collision The implementation of this approach wrote in MATLAB m file is Code 3 Collision detection for rough model of workcell l 700
18. robot workcell 223 0200 niawiiniendduadnnhuiiendsad 36 4 9 The graphical user interface for collision detection esse 37 4 10 Trajectory planning for collision detection eeeseee 38 5 GIU OIM PO 4 References III Appendix 1 MATLAB code for collision detection GUI ss Appendix 2 MATlab code for modelling workcell sess Appendix 3 MATlab code for trjectory planning approach for collision detection IV LIST OF FIGURES Figure 1 Extruded and swept volumes In the extruded volumes situation collision Is detected Jimenez 2000 ete oidaeaccsSetcheSbats Cacotesdetesdtbatacesies chestanse 4 Figure 2 Extruded and swept volumes The extruded volumes do not interfere but the swept volumes in x y plane are the same as in figure 1 Jimenez 2000 5 Figure 3 Adjustable sampling The start position is shown in a the closest points and the line connecting them are computed The projections of the objects on this line meet at instant b at this moment the new closest points are calculated at c At d the polygons collision occurred the collision points is computed in the same way Gilbert 1989 sseseeeeneree 5 Figure 4 Speed and torque diagram ABB Robotics 2007 esses 8 Figure 5 Robot scan with
19. speed assembly robot is installed in it Some features of this cell are it capable of processing 5 kg parts six tool change heads for loading different tools and very flexibility Sony conveyor system made it easy for connecting with feeders pallets for handling materials and components mounted with Omron PLC high accuracy frame and the mounting board The picture of the workcell is shown in figure 13 4 IMPLEMENTATION 30 1543 Figure 13 Sony SRX 611 robot workcell SSONY SRX 4 2 Define and model the robot For modelling the Sony SRX 611 robot MATLAB and robotics toolbox are used In this toolbox the link and robot commands are the main commands for constructing graphical robot in MATLAB The main part of MATLAB code to construct robot is discussed below Code 1 Define and model the robot 11 link 0 350 0 50 0 standard 12 link 0 2500 0 0 standard 13 link 00 0 720 1 standard 14 link 0 0 0 300 0 standard qiInput 1 885 0 062832 0 1885 0 75398 rob robot 11 12 13 14 figure plot rob qInput For plotting the robot drivebot rob First four lines in the code are used to create a separate link of the manipulator For in stance the first link is created with the four parameters according to the standard De navit Hartenberg notations The first parameter is alpha which is the angle between Z and Z
20. the virtual environment it takes a lot of time for the collision detection algorithm to check the possible crash happens So it s important to have a fast and effective algorithm After survey from the web various collision detection tools are found they are not only to be used in robotics and they are used in more wide area A list of the tools Table 1 A list of different collision detection software Name Description Link SOLID Software library for interference http www win tue nl gino solid i detection ndex 1 html Bergen 1997 RAPID A robust and accurate polygon http gamma cs unc edu OBB interference detection library RAPID 1997 Enhanced A package for incrementally http www cs ox ac uk stephen ca GJK computing the distance between meron distances Cameron 1998 convex polyhedron V Clip An improved implementation of http www merl com projects vcli the Lin Canny closest feature p MERL 1997 tracking algorithm as used in I COLLIDE V COLLIDE A collision detection library for http gamma cs unc edu V large environments COLLIDE Cohen 1998 SWIFT A library for collision detection http gamma cs unc edu SWIFT distance computation and con Ehmann 2000 tact determination of three dimensional polygonal objects undergoing rigid motion rota tion and translation 2 2 Collision detection in current industrial robots 2 2 1 Collision detection function in ABB ro
21. user interface in MATLAB there are several things to con sider Before starting to create it the requirements and the goals of the GUI should be considered this consists of defining the input output display and the behaviours of the GUI During the design of GUI each of its components should be programmed for functionally correctly The process of designing GUI is presented in the picture below Designing a Graphical User Interface Understand Specify GUI s Requirements Inputs Purpose Controls Add Use cases Displays another Interactivity Behavior window or Functionality Outputs dialog mock up or prototype Design GUI s Sequencing Grouping Labeling Styling Program GUI s Test GUI s Generate GUI s Initialization Unusual inputs ia GUIDE via i Actions Default actions via programming Coordination Error handling Data management Wrong results Shutdown Ease of use Figure 10 Process of designing GUI MATHWORKS 3 APPROACH 18 3 3 1 Basic model of collision detection user interface At the early stage of the user interface for collision detection development a basic user interface is made for the requirement of detection collision between a robot and work cell The workcell here refers to a cuboid where the robot is located inside it The GUI contains two edit boxes and one push button one of the edit boxes is for inputting the robot position after pu
22. x2 700 x yl 700 y2 700 z1 1260 z2 1260 T fkine rob qInput T 1 4 2 T 2 4 3 3 4 If T1 x1 T1 x2 T2 yl T2 gt y2 T3 z1 T3 z2 display Collision Else display No Collision End The first three lines of code are the minimum and maximum value in x y z axes for the cube shape object In the fourth line of code the command fkine is used for determine robot forward kinematics for serial link manipulator From the calculation of robot for ward kinematics the coordinates of the robot end effector for x y z axis coordinate can be obtained and they are T1 T2 and T3 respectively which are written in fifth to sev enth lines In the eighth line of the code is the condition for detecting collision if any of the coordinates of the robot is out of the cell s coordinate range and then the collision occurred In the ninth line to the last line of the code is for displaying the collision re sult When this m file get joint variables as input as the result of m file execution user 4 IMPLEMENTATION 33 can get information about whether the collision of robot manipulator and the cube has occurred This is a very basic and simple way to detect collision which is used at the beginning of collision detection development in the thesis 4 5 3D objects in the workcell As trails for drawing the entire robot workcell work at this st
23. 00 50 50 150 150 500 500 700 700 500 500 500 500 500 q t plot 012 t 34567 8 9 10 q color k hold on 500 500 500 500 500 500 q t plot 300 0 1 2 t 300 300 300 300 3456789 10 q eolor k 300 300 300 300 300 300
24. 102 103 104 400 The distance is computed by equation Distance J x y z 8 4 IMPLEMENTATION 34 The code for this part is Code 4 General function for collision detection m 700 200 200 n 100 400 400 x1 m 1 yl m 2 zl m 3 r x2 x1 n 1 y2 yltn z2 zltn 3 xaxis x1 x2 yaxis yl y2 zaxis z1 z2 For xaxis x1 x2 For yaxis yl y2 For zaxis z1 22 If sqrt Tl xaxis Tl xaxis T2 yaxis T2 yaxis T3 zaxis T3 zaxis lt 1 Display Collision End For End For End For End If In the first line of this code is the start point of the cube shape object The second line of code is the size of this object in x y z axes The following six lines of code is for getting the starting point and ending point value for the cube in x y z axes The ninth to eleventh lines of code are for putting the coordinates of the cube into three variables they are xaxis yaxis and zaxis From the twelfth to fifteenth lines are using for loop to search all the coordinates values of the cube in three dimensions The sixteenth line of code is a calculation of the distance between robot and the cube in x y z axes to see if the distance is less than 1mm This threshold value also can be modified by user In the seventeenth line of the code is a displaying of collision result The second approach used for
25. 420 1500 color k line 700 700 15 15 420 1500 color k line 15 15 700 700 420 1500 color k line 15 15 700 700 420 1500 color k axis 1500 1500 1500 1500 1500 1500 guidata hObject handles Executes on button press in cube pushbutton function cube pushbutton Callback hObject eventdata handles hObject handle to cube pushbutton see GCBO figure 1 a get handles StartX edit String b get handles StartY edit String c get handles StartZ_edit String d get handles SizeX_edit String e get handles SizeY_edit String f get handles SizeZ_edit String voxel str2double a str2double b str2double c str2double d str2double e str2double f 0 0 0 6 0 2 1 0 voxel 700 700 930 200 200 200 1 0 0 0 6 0 2 1 0 guidata hObject handles o Executes on button press in productline pushbutton function productline pushbutton Callback hObject eventdata handles hObject handle to productline pushbutton see GCBO figure 1 conveyor green voxel 700 700 900 1400 70 70 0 5 0 5 0 5 1 0 voxel 700 700 830 1400 70 30 0 0 0 6 0 2 1 0 sconveyor black voxel 700 470 900 1400 70 70 0 5 0 5 0 5 0 9 voxel 700 470 830 1400 70 30 0 0 0 0 0 0 1 0 sconveyor hold par
26. 8 create a conveyor line by voxel function 19 create the holding part of the conveyor by voxel function 20 store the variable data in this section as GUI data 21 function name is addRobot_pushbutton_callback this is for loading graphical robot 22 create link object 11 to n 23 get the value of initial joint variable q 24 construct a robot object from a cell array of link objects 25 hold the current graph 26 store the variable data in this section as GUI data 27 function which name is RemoveFrame pushbutton Callback 28 remove all the figures 29 store the variable data in this section as GUI data 30 make a function which is for creating the text box for inputting x axis value for constructing cube 31 get the input value and convert it to the double data form 32 store the variable data in this section as GUI data 33 repeat this same action for y axis input text box and z axis input text box and also for the text box for inputting the size of cube in X y Z axis 34 make a function for creating sphere object in the workcell 35 create a sphere and get the coordinates of the sphere x y z 36 get the size value of the sphere from the input box 37 get x y z coordinates of the centre of the sphere from input boxes 38 create a shaded surface for the sphere by command surf 39 store the variable data in this section as GUI data 40 make a function which is for creating the text box fo
27. In this thesis MATLAB is the main modelling software used MATLAB program is very good at numerical computing visualization and analysis MATLAB is used for model ling the robot with the aid of robotics toolbox for MATLAB In this thesis the objects in the robot workcell is also modelled it contains the conveyors cube and sphere shape objects in the workcell MATLAB is also used for collision detection this include the creation of graphical user interfaces for controlling robot and workcell and develop ment of the collision detection algorithm Practical simulation system and analyse tools are very important for modelling and solving collision problems In such system it re quires the tools can make geometric modelling and physical sampling Lin 1996 In this section the approach of building 3D objects and workcell in MATLAB is intro duced For building the 3D objects in MATLAB there are several ways to do this The purpose of making 3D objects is for building the robotics working cell and components within the working cell The most basic elements for constructing the workcell is the line ele ment multiple lines can construct different size of cubes The command Line creates a line objects with default values x 0 1 and y 0 1 MATHWORKS The syntax of line is line x y Z property name property value 3 Beside the line command another command voxel is used Voxel made by Joel 2003 is a simple function to draw a cube
28. RKS compamy SimMechanics User s Guide 2005 Sony SRX 611 robot specifications in the webpage http isbergsprodemo se page9 files sony srx pdf Accessed September 2011 Zlajpah L Simulation in Robotics The Jozef Stefan Insti tute Ljubljana Slovenia 2008 47 APPENDIX 1 MATLAB CODE FOR COLLISION DETECTION GUI function varargout MyAdderShapeGUI varargin MYADDERSHAPEGUI MATLAB code for MyAdderShapeGUI fig Begin initialization code gui Singleton 1 gui State struct gui Name mfilename gui Singleton gui Singleton gui OpeningFcn MyAdderShapeGUI_OpeningFcn gui OutputFcn GMyAdderShapeGUI OutputFocn gui LayoutFocn Es gui Callback if nargin amp amp ischar varargin 1 gui_State gui_Callback str2func varargin 1 end if nargout varargout l nargout gui_mainfcn gui_State varargin else gui mainfcn gui State varargin end End initialization code DO NOT EDIT oo Executes just before MyAdderShapeGUI is made visible function MyAdderShapeGUI_OpeningFcn hObject eventdata handles varargin hObject handle to figure eventdata reserved to be defined in a future version of MATLAB handles structure with handles and user data see GUIDATA oo varargin command line arguments to MyAdderShapeGUI see VARARGIN Choose default command line output for MyAdderShapeGUI handles output hObject Update handles
29. a link object 11 to n 2 get the value of initial joint variable q 3 construct a robot object from a cell array of link objects and the initial joint q 4 compute the forward kinematics for each joint space point de fined by q and robot object and set this result to T 5 get the end effector coordinate in x y z axis from T 6 if the end effector s coordinates within the cube s coordinates in X Y Z 7 display collision message 8 else 9 display no collision message 10 end if For the second situation it needs to determine if the robot has collision with the cube objects around it The coordinates of the cubes are defined so all the coordinates within the cubes is searched by a for loop in MATLAB if the distance between any of those coordinates and the coordinates of the robot less than 1mm then they have collision The algorithm for this part is Algorithm 8 Collision detection by calculating distance for cube shape objects Name Collision detection by calculating distance for cube shape objects Description This algorithm shows another approach to solve collision detec tion problem between robot and cube shape objects which is to calculate the distance between robot and objects if they are equal to zero then collision occurred Steps 1 for each coordinates between the start and the end coordinates for x axis of cubel 2 for each coordinates between the start and the end coord
30. age more cube shape ob jects has been tried to add to the cell Here the voxel function is used again to create new cubes and shapes constructed by cubes The voxel function is easy to use need to define the start point coordinates and the size of the cube and then define the colour of it By repeating this way of making cubes the result of this process is shown in the fig ure 16 1000 1000 Figure 16 Robot workcell with many cube shape objects The sphere shape object is also made in MATLAB for adding sphere into the workcell The approach of creating sphere is presented in the chapter 3 algorithm 2 4 6 General function for collision detection For detecting collision between robot and the cube and sphere shape objects inside the robot workcell several approaches have been found All of them are three approaches two approaches are used for detecting collision between robot and cube shape objects one approach is used for detecting collision between robot and sphere shape objects The first approach for the cube shape object and robot is by calculating the distance between robot end point and a point which within a cube in the air if the distance is less than Imm then it will give output collision To get the inside coordinates of a cube here is to get the entire sets of coordinates along x axis y axis z axis they have Imm interval between each other in each axis for example in x axis the x axis coordinates are 100 101
31. ajectory can be plotted by command ctraj When the figure of trajectory of the robot tooltip is obtained then plot the range of X y Z coordinates of the bounding box in the same picture After getting both trajectory of the robot and bounding box in the same plot the figure can be analysed at the place where the first time robot s x y z coordinates are all within the bounding box s coordi nates that is the first point the collision start by graphical analyse tool the points caus ing collision can be found The algorithm for this method is presented below 3 APPROACH 27 Algorithm 10 Trajectory planning for collision detection Name Trajectory planning for collision detection Description This algorithm first build trajectory of the robot then plot the co ordinate range of the bounding box of obstacle in the same figure after these steps graphical analyse tool is used for analyse the collision points Steps 1 create link objects 11 to n 2 define the initial position for robot 3 plot robot 4 build a bounding box model for obstacle by voxel function 5 define the start point for robot trajectory 6 define the end point for robot trajectory 7 define the time length for this motion 8 create the path vector r with continuous derivatives by jtraj function 9 create the Cartesian path with smooth acceleration r 10 plot this trajectory 11 hold on the cu
32. and sphere shape objects and other components inside the working cell From the study of MATLAB programming there are different ways to create 3D ob jects in MATLAB One of the common approaches is visualizing the 3D object by mesh and surface plot commands In this thesis the basic lines and planes plot is used to make the frame and layers of the working cell An approach of making the robot workcell by MATLAB is developed For creating objects which appears inside the working cell here it refers to only two shapes one is cube shape object and another is sphere objects Certain command for certain shapes of objects is used From the study of theories of collision detection algorithms different algorithms have been developed in different computer languages in the areas of computer graphics But from the surveys which have done through internet among all the journals books articles there are very few colli sion detection research about robotics has been made by MATLAB while MATLAB is utilized in very wide range of applications in industry and academia So it is needed to develop approaches for robotics modelling and collision detection by MATLAB The structure of this thesis is organized in the following order Chapter 1 is the intro duction of the entire thesis work introduce the background of robot working cell model ling and the detection collision of robot And a description of the objectives which is going to be solved in this thesis is
33. bots ABB robots are one type of the most widely used robots in the industry production sys tem and other service the collision detection already designed as part of its functions This advance operation only can be found in some of the robots for example it s availa ble in the ABB robot KUKA robot and Fanuc robot Luca 2006 In the ABB robot controller RobotWare and the simulation and ABB robot offline programming software RobotStudio they both have the collision detection option but their methods are differ 2 STATE OF ART 8 ent In the RobotWare the high sensitivity model based supervision is used to detect collision The sensitivity option can be turned on and off depends on how much force applied to the robot In the system parameters setting in the motion supervision it in clude path collision detection jog collision detection supervision levels for path and jog and collision detection memory to define how much robot moves after collision When robot detected collision it will stop and move to the opposite way of the force which is left The robot will continue to work only after a collision message has been received The picture below shows the order of events during and after the collision first when the collision is detected then the motor torques are changed into opposite direction and the robot will stop because of the mechanical brakes After the robot stopped the robot will move in the opposite direction a small le
34. ce which also can load graphical robot workcell and other objects This inter face can detect the collision between robot and environment Steps 1 initialization of the code 2 function name as frame_pushbutton_callback 3 figure 1 4 create a frame by voxel function by defining coordinates and size 5 create the top part of the frame by voxel function defining coord nates and size 6 create the bottom layer of the upper part of frame by voxel function defining coordinates and size 7 create the middle layer of the frame by voxel function 8 create another middle layer of the frame by voxel function 9 create the base for the frame by voxel function 10 create the outer layer lines 11 store the variable data in this section as GUI data 12 make a function which name is cube_pushbutton_callback for the cube which is going to be inserted in the working cell 13 get the string value of the x y z axis coordinate of the start point of the cube from the edit box 14 get the string value of the size of cube in x y z axis from edit box 15 use the six values got from above six steps build a cube by voxel function the cube will be inserted in the same figure with the 3 APPROACH 22 graphical robot 16 store the variable data in this section as GUI data 17 function which name is productionline_pushbutton_callback 1
35. collision in real time After being able to get the result of collision from the input position manually at this part it is improved to be able to see the result in real time whenever user moves the slider in the drivebot interface to manipulate the robot By modify the original drivebot m file made it possible to catch and use the real time coordinate of the robot end effec tors and then give the result which will be displayed in the GUI The code for this is Code 6 Detect collision in real time If xl str2double 35print 3f t6 1 4 amp amp str2double sprintf 3f t6 1 4 x2 amp amp yl str2double sprintf 3f t6 2 4 amp amp str2double sprintf 3f t6 2 4 lt y2 amp amp zl str2double sprintf 3f t6 3 4 amp amp str2double sprintf 3f t6 3 4 z2 Scompute collision Assign collision message to result lse Assign no collision message to result End If The first line of the code is used for comparing the coordinates of the robot with the coordinates of the coordinate range of object The long representation due to the need of converting data type and to get the real time values of robot This code only shows the main part for collision detection in the entire real time collision detection code The second to the fifth lines of code are used for giving collision situation messages This makes whenever user moves the slider in the interface this is
36. con tact More complex versions might ask to obtain information of the time and features that related to the collision Usually for solving these problems is to give constraints to the input this helps simplify problems In the given parameter space the objects often presumed to be polyhedral and convex the motions are bounded to be translational or linear Lin 1993 Many of the approaches which are used for solving collision problem have tried to reduce the complex of computing Generally the approaches can be classi fied to geometric type and algebraic type The geometric type of solutions involves ana lyse the extruded volume in a lower dimensional subspace and path sampling The al gebraic type involves the path parameterize 2 STATE OF ART 4 2 1 1 Approaches to collision detection Spatio temporal intersection Extrusion action is one of most common representation in the collision detection study The spatiotemporal series of points stand for the occupied space of the object with its trajectory is the extruded volume Only in the situation when the volumes of two objects cross each other then a collision between these objects happens Cameron 1990 The extrusion action is distributive with regard to the coupling overlap part and set dif ferent operations This stimulated the improvement of the extrusion approach in the background of constructive solid geometry CSG modelling CSG means a kind of sol id modelling technique that al
37. d for creating manipulator link the command for constructing robot is robot in robotics toolbox in MATLAB 3 APPROACH 17 3 3 Graphical user interface for collision detection The graphical user interface GUI is a graphical display in one or several windows that contain controls and make it possible for the user to do tasks interact with the MATLAB program The user only needs to click some buttons in the GUI they do not need to write the script or commands in the MATLAB command window to do the work And the users do not need to know the working principle behind the GUI interface The most usual objects displayed in GUI are menus toolbars push buttons radio buttons sliders edit boxes list boxes The working principle of GUI is when the user operates a control the GUI will give response to each control One main part of GUI algorithm is the call back functions The call back functions for call back to MATLAB ask it to do certain action The call back action usually generate by user pushing a button in the GUI or by user selecting an item from the menu or by the user input a type of value The GUI has reaction to these events The task for the GUI maker is to define the callbacks and the components the events There are two ways of writing call back code in MATLAB one is that write callbacks as MATLAB functions which save as m files the other way is write callbacks as part of MATLAB strings MATHWORKS When designing graphical
38. detecting collision between robot and cube shape objects is by comparing the coordinates of the robot end effectors and the maximum and mini mum value of coordinate of the cube in each axis The approach used for detecting collision between robot and sphere shape objects is by comparing distance between the centre of the sphere and the coordinates of the robot If the absolute value of the distance difference is greater than the radius of the sphere then no collision occurred otherwise the collision happened The main part of the collision detection code is presented below Code 5 Collision detection code for robot and sphere shape objects r 50 set a value for the radius of the sphere xs 700 coordinates for the sphere centr ys 200 zs 200 If abs Tl xs r amp amp abs I2 ys r amp amp abs T3 zs gt r display No Collision else display Collision 4 IMPLEMENTATION 35 End The first line of this code is used to set a value for the radius of the sphere The second to the fourth line of this code are used for giving the sphere centre values to variables The fifth line of the code is the condition for determining collision between sphere and robot if the absolute value of the distance between robot and sphere is greater than the radius of the sphere then they do not have collision The last four lines of the code are used for displaying results 4 7 Detect the
39. detection algorithms the geometry data does not need to be kept in any special format in this GJK algorithm but instead only depend on a support function to iteratively generate closer simplexes to the right answer by using the Minkowski addition method for convex pairs Gilbert 1988 The GJK method solves nearness queries for the given two convex polyhedra it can compute shortest distance between them it also can find the closest pair of points This can be applied for any convex objects if they can be defined by a support mapping function Ericson 2004 2 1 6 Tools for collision detection Collision detection has been a basic problem in computer animation 3D modelling and geometric modelling and robotics Usually the collision between two moving objects is modelled by dynamic restraints and the analysis of the intersection in these applications Also the movements of the objects are restrained by several interactions contains the collision Several collision detection tools have been developed by researchers around the world most of them created in a virtual environment The virtual environment is a world gen erated by computer contain virtual objects in it This type of environment should give 2 STATE OF ART 7 people the existence feeling which means make the objects in the environment looks solid For example the objects should not go through each other the movement of ob jects should be as planned When the object moves in
40. e GUI for this drivebot function by defining the width and height 25 if the number of function arguments less than two 26 set q zeros 27 else 28 if the input b is character array 29 setq b 30 end 31 end 32 compute the forward kinematics for each joint 33 check if there are any graphical robots of this name if so then use them otherwise create a robot plot 34 get the current joint configuration of graphical robot 35 make the sliders for each robot link 36 create three text boxes for x y z axis value of the robot end effector 37 end In this algorithm it can be seen as it is divided into two parts by the else in the step 25 before else it mainly making the connecting with the part after else like getting data and the calculation of collision between robot and the cube objects in the workcell The part after else mostly for making components for this graphical user interface like build the siders input boxes display result box etc Within this chapter of code the commands from robotics toolbox are fkine for computing the forward kinematics and the end ef fector s coordinates can be getting from it robot for building robot object The im provement of this interface is it can detect the collision in real time when user moves the slider this algorithm computes the collision at the same time After this real time collision detection interface is made there are more requirements found shou
41. ect 11 ton 11 create robot by 11 ton 12 calculate the forward robot kinematics 13 get robot end effector coordinate Tx Ty Tz 14 if the robot s end effector coordinate is not within the workcell 15 display collision 16 else if robot s end effector coordinate is within the workcell 17 display no collision 18 end 3 APPROACH 19 19 set this result to edit box 2 This algorithm contains two parts step 1 6 is for making the outward appearance of the GUI step 7 19 is the call back part of the push button the push button is made within the step 1 6 3 3 2 Collision detection interface At the beginning of making the GUI for collision detection the requirements considered are the detection of collision and it need to be able detect collision in real time Based on these two requirements the original drivebot file is modified There is collision dis play part has been added to the original interface Drivebot is a function for driving a graphical robot it s a pop up window contains sliders for moving each joint When user moves the sliders by mouse it will move the corresponding robot link in the screen This interface is very good for the view of robot joints links and workspace Corke 2008 By using this modified drivebot function it makes whenever user moved the slid er in interface for controlling the robot links then the user can see if the robot collision with other
42. ection will be easier to the user several graphical user interfaces GUI are made And also the making of GUI for real time collision detection is problematic But after a period of time to practice with the programming commands and the creating GUI skills and read several very helpful research articles these problems are overcome By the end of this thesis all the goals are achieved a robot working cell is modelled in MATLAB the working cell in cludes a conveyor cube or sphere shape objects inserted by the user GUIs that can con trol the graphical robot movement and to add the working cell conveyor and objects to the same figure as the robot located The GUI can detect if there is collision between robot and the environment And the collision detection algorithm also made during the process of making the controlling GUI Several graphical user interfaces for collision detection are created during this thesis work The purpose of making different interface is for user easier to control robot and the objects in the workcell and get feedback about the collision situation In the final version of interface it realized the function of inserting cube shape objects sphere ob jects conveyors to the workcell The user can define size of the object and the location of the object In the designed scenarios when the robot detects there is collision be tween robot and other objects in the workcell the robot will have an emergency stop The collision
43. effector coordinate in x y z axis from T name them as T1 T2 T3 6 assign a value for the radius of the sphere 7 get the coordinates of the sphere centre point name them as xs ys ZS 8 if absolute value of the distance difference of the centre point of sphere and the robot manipulator is greater than the radius of the sphere 9 display no collision message 10 else 11 display collision message 12 end if After introduced these three approach of collision detection with the collision detection user interface described earlier in this chapter the usage of this entire collision detection tool is The objects appear in the workcell include conveyors cubes spheres 3 APPROACH 26 3 5 Trajectory planning for collision detection There are two ways to generate trajectory one is joint space schemes and another is Cartesian space scheme Joint space method is the path shapes in space and in time are described in terms of functions of joint angles In Cartesian space schemes it consider methods of path generation in which the path shapes are described in terms of functions which compute Cartesian position and orientation as function of time Craig 2004 When trajectory is planned in the joint space its mathematical representation is cubic polynomials A cubic polynomial has 4 coefficients may be used to satisfy both posi tion and velocity constraints at the initial and final positions For joint variable
44. en all points of the robot contains the points in the surface can be controlled and the path of robot motion can be planned The collision detection method used here is part of multiple interference detection method Reichenbach 2003 Figure 7 Kinematic chain is created from the point where collision occurred Reichenbach 2003 2 2 6 Other robot modelling methods There are also many other tools have been used in robotics modelling and collision re search one of them is SimMechanics toolbox SimMechanics extends Simulink with the tools for modelling and simulating mechanical systems With SimMechanics you can model and simulate mechanical systems with a suite of tools to specify bodies and their mass properties their possible motions kinematic constraints and coordinate systems and to initiate and measure body motions SimMechanics Similar as in MATLAB the robot system can be simulated in Dymola and Modelica or 20 sim Here the library provides three dimensional mechanical components to model rigid multi body systems such as robots The robot system is built by connecting blocks representing parts of the robot like link bodies joints actuators etc Figure 8 shows the block scheme of a complete model of the KUKA robot including actuators gears and the controller Kazi 2002 2 STATE OF ART 12 axis6 mechanics Figure 8 Simulation of a robot with Modelica Kazi 2002 Another tool is planar manipula
45. environment for the later collision detection study After the models are built then the collision detection user interface is made From this implementation it shows that this approach is applicable to the existing workcell 41 5 CONCLUSION This thesis solved the robotics modelling environment modelling and collision detec tion problems all the main objectives of this thesis work are achieved In the literature review part several modelling approaches and collision detection methods are present ed those are the most related research has done in the robotics modelling and collision by MATLAB For resolve the robotics modelling and environment modelling problem MATLAB software is used The robot is modelled by robotics toolbox for MATLAB Robotics toolbox is a very useful tool for modelling robot in MATLAB program About modelling of the surroundings of the robot the surroundings include workcell convey ors cube shape objects sphere shape objects Those objects are built from the basic MATLAB graphical components like lines planes While the actualization of the two goals of this thesis work there has been came across several problematic situations For example at the time when search for the research documents about collision detection in robotics by MATLAB it does not have much documents about using MATLAB for robotics collision problems it is challenge to find the solution for these two objectives For making the collision det
46. es situation collision is detected Jimenez 2000 2 STATE OF ART 5 Figure 2 Extruded and swept volumes The extruded volumes do not interfere but the swept volumes in x y plane are the same as in figure 1 Jimenez 2000 2 1 3 Multiple interference detection Sample the object route and frequently make a static interference test to it is one of the easiest way to deal with collision problems The way of how sampling is done matters the final result of this method If the sampling is too rough it will cause some collision result missing Also a too fine sampling will make the computation too huge The rec ommended solution is to use adjustable sampling More experienced solution not only computes distance but also get information about direction One solution in this way described in Gilbert 1989 need to compute the closest points of two convex polyhedrons at the instant time sample and also determine the line connect them At the moment when the projections of the objects meet on the line is used as the next time sample In the figure 3 Therefore this method can be con sidered as a mix of sampling and projecting onto subspaces which is in lower dimen sion Figure 3 Adjustable sampling The start position is shown in a the closest points and the line connecting them are computed The projections of the objects on this line meet at instant b at this moment the new closest points are calculated at c At d the polygons c
47. evaluate product Most common approach for collision detection is based on detection of interface and distance calculation In this section the main collision detection approach is presented There have been three approaches developed for collision detection between robot and cube sphere shape objects The first collision detection algorithm is made for detecting collision be tween graphical robot and cube shape objects around it The second collision detection algorithm is also for detecting collision between robot and cube shape object but using another way to do it the distance between robot and objects has been calculated The third collision detection algorithm is made for detecting collision between robot and sphere shape objects For the first situation only concern the collision between robot and the cuboid workcell and cube shape objects the algorithm is presented below Algorithm 7 Collision detection by comparing coordinates for cube shape objects Name Collision detection by comparing coordinates for cube shape ob jects Description This algorithm is for detecting the collision between robot and cube shape objects around it the approach used for detecting col lision is by comparing the coordinates of the robot and the objects if the coordinates of the robot is within the coordinates of the ob 3 APPROACH 24 jects then collision occurred Steps 1 create
48. i nates for y axis of cube 1 3 for each coordinates between the start and the end coor dinates for z axis of cube 1 4 repeat the 3 steps above for all the cubes 5 if the distance between the robot s end point and one point within the cube is equal to zero 6 display collision message 3 APPROACH 25 7 end for 8 end for 9 end for 10 end if In the third situation is to detect the collision between graphical robot and the sphere shape object in the workcell The algorithm of this part is Algorithm 9 Collision detection by comparing distance for sphere shape objects Name Collision detection by comparing distance for sphere shape ob jects Description This algorithm is for detecting the collision between robot and sphere shape objects in the workcell the approach used for detect ing collision is by comparing distance between the centre of the sphere and the coordinates of the robot If the absolute value of the distance difference is greater than the radius of the sphere then no collision occurred otherwise then the collision happened Steps 1 create a link object 11 to n 2 get the value of initial joint variable q 3 construct a robot object from a cell array of link objects and the initial joint q 4 compute the forward kinematics for each joint space point de fined by q and robot object and set this result to T 5 get the end
49. ibed in Chapter 3 for modelling robot workcells and making the collision detection tool is detailed The robot model selected to demonstrate the usage of the approach is Sony SRX 611 Final results of robot and workcell modelling collision detection user interfaces implementation are presented in this chapter 4 1 The robot and workcell In Chapter 3 the approach of modelling robot and workcell is discussed In this chapter the Sony SRX 611 robot and the corresponding workcell is chosen as an example to demonstrate the usage of the modelling approach The real SRX 611 robot and workcell are located in the Factory Automation System and Technologies laboratory in Tampere University of Technology 4 1 1 Sony SRX 611 High Speed Assembly Robot The Sony SRX 611 robot is built with brushless AC servo motors and absolute encod ers PLC is one way of control of the robot The robot weights 35 kg and the suggested payload is from 2 kg to 5 kg it can operate with maximum 5 kg components it mainly do parts assembly and material handling tasks The technical advantage of Sony SRX 611 are time and cost savings reusable which means when apply some change to the installation the equipment can be used as a standard unit high quantity of production for parts handling task high accuracy in the production to ensure the quality low floor space requirement this made easy to reach the device and space saving The appearance of the robot is shown in figu
50. ify exist ence of the motionless obstacles on the manipulator robot a model based fault detection and isolation FDI algorithm is made By using the FDI algorithms created directly from the related graph model a list of analytical redundancy relation ARR together with the corresponding fault signature matrix can be computed The principal of this approach is the usage of ARR theory not to detect a faulty actuator but to detect an external joint obstacle which stops the normal operating of the faulty actuator Fawaz 2009 External Collision Trajectory e Generation E f F 72 Residuals u Figure 6 Residuals generation from virtual real time simulator Fawaz 2009 2 2 5 Derivation of kinematic parameters method In this method real time collision detection algorithm based on the application of ori ented bounding boxes OBB and the triangle is used for finding the precise collision 2 STATE OF ART 11 point The triangle means the models in this method are non convex hierarchical poly gons constructed by triangles The point which collision occurred is used as a new end of a kinematic chain new kinematic parameters determined from collision triangles are calculated First generate a kinematics model from the virtual 3D model by using these acquired kinematic data from the collision point as one end of the chain a new kinemat ic chain is generated Th
51. in MATLAB the location and size of the cubes and spheres are defined by user The figure below shows the final version of collision detection inter face Bl MyAdderShapeGut o a Add Shapes to Robot Cell Adding Load Robot Add Cube Start from Add Frame x 700 Y 700 Z 700 Size X 200 MN z Add Conveyor is an Center Generate Sphere X 100 Y 700 Z 700 _ Se Radius 100 Clear All r Collision Detection Get Result No Collision Figure 22 Final version of collision detection GUI 4 10 Trajectory planning for collision detection The trajectory planning approach for collision detection is done with the aid of robotics toolbox and analysing of the plot The parameters of robot used for trajectory plot is list in the appendix 3 First plot both the trajectory of the robot and the obstacle in the figure 24 then start analyse the point where the collision starts this is shown in figure 25 Af ter executing the commands in algorithm 9 from Chapter 3 the result is shown in the figure 24 4 IMPLEMENTATION 800 600 Bounding box s x axis value range ee NNNM 400 200 length mm Bounding box s y axis value range 200 400 Bounding box s z axis value range 600 0 1 2 3 4 5 6 7 8 9 10 time s Figure 23 Trajectory of robot and coordinate range of obstacle s bounding box plot t
52. is TAMPERE UNIVERSITY OF TECHNOLOGY XIAOYUN DENG ROBOT WORKCELL MODELLING AND COLLISION DETECTION WITH MATLAB ROBOTICS TOOLBOX Master of Science Thesis Examiner Professor Jose L Mar tinez Lastra Examiner and topic approved in the Automation Mechanical and Materi als Engineering Faculty Council Meeting on 9 May 2012 ABSTRACT TAMPERE UNIVERSITY OF TECHNOLOGY Degree Programme in Machine Automation DENG XIAOYUN Robot Workcell Modelling and Collision Detection with MATLAB Robotics Toolbox Master of Science Thesis 53 pages 3 Appendix pages May 2012 Major subject Factory Automation Examiner Professor Jose L Martinez Lastra Keywords Robot Modelling Workcell Collision Detection MATLAB Robotics Toolbox Graphical User Interface The modelling of robotic systems and collision detection are important tasks for the manufacturing industry targeting the reduction of possible damages to the robot work ing environment and human operators The MATLAB software and its Robotics Toolbox are powerful tools for robotics modelling and collision analysis This thesis work was carried out at the Factory Automation System and Technologies Laboratory of Tampere University of Technology It provides approaches for the 3D modelling of robot workcell and its components by MATLAB These components include conveyors cube shape and sphere shape objects The thesis also provides an approach for collision detection between the robot and i
53. kcell also affects the working process of the robot The environment might contain elements of transpor tation system products robot and other structural elements An approach to model and analyse the robot and its workcell and an efficient algorithm for collision detection be tween robot and work environment is presented in this thesis To solve the problem of robot and workcell collision detection problem the first step of this thesis work is making models for robot and workcell There are several software can be used to model robot system in this thesis work MATLAB is used MATLAB is high level language and interactive environment that allows user to do intensive com putation tasks it is widely used in academic studies and research For applying MATLAB to robotics area robotics toolbox for MATLAB is available to use This toolbox is developed by P I Corke from Queensland University of Technology Many functions in this toolbox are helpful for studying and simulating the classical type of robot manipulator The kinematics dynamics parameters and trajectory of robot can be analysed by it Corke 2011 During this thesis work some functions are modified and developed for the use of collision detection this modification is based on the original robotics toolbox Made it possible to detect the collision between robot and workcell objects and modelled the entire working environment for the graphical serial link ma nipulator In the field
54. laser range finder LRF Microsoft 2012 9 Figure 6 Residuals generation from virtual real time simulator Fawaz 2009 10 Figure 7 Kinematic chain is created from the point where collision occurred Reichenbach 2003 cates 5 2 teens tid itedbtotesetetetetets less 11 Figure 8 Simulation of a robot with Modelica Kazi 2002 12 Figure 9 Dynamic model made by planar manipulators toolbox Hollars 1994 12 Figure 10 Process of designing GUI MATHWORKS eene 17 Figure 11 Sony SRX 611 robot PRODEMO eene 29 Figure 12 Specification of Sony SRX 611 robot SONY SRX 29 Figure 13 Sony SRX 611 robot workcell SONY SRX eese 30 Figure 14 A Sony SRX 611 robot model in MATLAB eene 31 Figure 15 A rough model of robot and workcell sess 32 Figure 16 Robot workcell with many cube shape objects sessssss 33 Figure 17 A real time collision detection user interface sseessss 36 Figure 18 A basic conveyor model 4e oet rentia tedio Derbi ducet isa 36 Ligure 19 Model of wotkeell eo eger oce ite tieni timete quisa 37 Figure 20 Initial GUI for detecting collision eeeee 37 Figure 21 Third stage of GUI development oot neta neas 38 Figure 22 Final version of collision detection GUI
55. ld be considered One function should be considered in this interface is that it should be able to load graphical robot and its workcell When user click buttons in this 3 APPROACH 21 interface it will automatically insert one kind of shape into the MATLAB robot model picture this interface will provide different shape choices like outside frame cubes conveyors etc At the same time after certain button is pushed it is able to see if the collision happened from another drivebot interface Next requirement to be considered is this interface should allow user input the cube or sphere shape of objects in the position where the user want it be And also the user can define the size of the objects Based on this concern the approach for making a collision detection tool is made There are six edit boxes below the add cube button this allows people input the coordinate and size of the cube it can just insert to the robot cell And there is generate sphere button in the choice also four input boxes allow people input the coordinate and radius of the sphere When the developments above are done next task is to integrate the real time collision detection function to this interface The algo rithm for this approach is Algorithm 6 Collision detection interface Name Collision detection interface Description This algorithm is for making a collision detection interfa
56. lows user to model the object by using Boolean operators Rossignac 1986 Because the extrusion action has the property of distributive it as sures that an object and its extruded volume can be represented by the same Boolean combination The drawback of this method is it will generate 4D extruded volumes the calculation in 4D for the extruded volumes is difficult Jimenez 2000 2 1 2 Swept volume interference The definition for swept volume is the points that moving object contains over certain period of time If the swept volumes for all the objects in a scene do not cross each oth er then there is no collision between them during the certain period of time But also need to consider another situation it might happen that the swept volumes crossed but no collision occurred This state demonstrated in the figure 1 and 2 In both conditions same swept volume in the x y plane can be seen but the collision occurred just in figure 1 not occurred in figure 2 Jimenez 2000 In order to avoid the incorrect estimation which happens in the figure 1 and 2 for each two objects the sweep operation need to be done by the correlative movement of one object with regard to the other object In this condition one of the objects is viewed as fixed the swept volume of the other object within this movement is calculated The drawback of this method still is the big amount of calculation work Figure 1 Extruded and swept volumes In the extruded volum
57. many arguments for voxel 16 end A assign a three columns and eight rows matrix value for x x is con structed by the start coordinates I 1 I 2 I 3 and the size in three dimensions d 1 d 2 d 3 and zeros in the corresponding place 18 for n from 1 to 3 19 ifn 3 20 then sort the rows of x first in ascending order for 3 APPROACH 15 the third column and then sort the rows of x in ascending order for the first column iy else 22 soprtthe rows of x first in ascending order for the number n column 23 and then sort the rows of x in ascending order for the n 1 column 24 end 25 get the first 4 rows of values of the three columns of x 26 construct a cube shape polygon by the value above by function patch 27 get the 5 to 8 rows of values of the three columns of x 28 construct a cube shape polygon by the value above by function patch 29 end Other 3D objects made in MATLAB is the sphere the sphere is made by the command sphere in MATLAB The sphere function generates a sphere in the x y z coordinates The script written as Algorithm 2 Create sphere in MATLAB Name Create sphere in MATLAB Description For draw a sphere in MATLAB command surf and mesh are used for construct the sphere Steps 1 figure 1 2 Set x y z as parameters of the function sphere 3 set radius valuer 4 set the cent
58. mental to robotics like homogeneous transformations trajectories In this toolbox functions are provided for arbitrary serial link manipulators include forward and inverse kinematics Jacobians dynamics Corke 1995 This toolbox is suitable for simulation it is also very helpful for analysing the results of experiments from real robots and it is a powerful tool for education and research The principle of the toolbox is according to a general approach by using description matrices to denote the kinematics and dynamics of serial link manipulators The inverse dynam ics is computed by using the recursive Newton Euler formulation In the beginning it is designed to be used with MATLAB but now it also can be used with Simulink Corke 1995 For creating robot in MATLAB the algorithm for this usage is presented below Algorithm 3 Create robot in MATLAB Name Create robot in MATLAB Description For making graphical robot in MATLAB robotics toolbox is used Data structures a Rotation angle Rotation angle 0 a Translations in Denavit Hartenberg link parameters d Translations in Denavit Hartenberg link parameters Steps 1 create the link from a a 0 d for link 1 to n 2 set initial position value q 3 create the robot from link 1 to n 4 figure 1 5 plot the robot with robot and q Here parameter a a 0 d are determined by Denavit Hartenberg DH method link is the comman
59. n detection and safe reaction with the DLR III lightweight manipulator arm IEEE RSJ International Conference on In telligent Robots and Systems Beijing China 2006 MATHWORKS MATLAB Product Help Documentation Homepage _http www mathworks se help techdoc Ac cessed March 2012 MERL A Mitsubishi Electric Research Lab V Clip Collision Detection Library http www merl com projects vclip Ac cessed May 2012 Microsoft Robotics Robotics Tutorials 2012 Moore M Wilhelms J Collision detection and response for computer animation ACM Computer Graphics 1988 SRX 611 Robot in PRODEMO Company http isbergsprodemo se page9 page9 html Accessed Sep tember 2011 Homepage Reichenbach T Kova i Z Derivation of Kinematic Param eters from a 3D Robot Model Used for Collision Free Path Planning University of Zagreb Faculty of Electrical Engi RAPID 1997 Rossignac 1986 SICK 2008 SimMechanics SONY SRX Zlajpah 2008 46 neering and Computing Croatia 2003 RAPID A robust and accurate polygon interference detection library for large environments composed of unstructured mod els http gamma cs unc edu OBB Accessed May 2012 Rossignac J R Requicha A A G Depth Buffering Display Techniques for Constructive Solid Geometry IEEE Comput er Graphics and Applications 1986 SICK AG Sick LMS200 series laser range finder LRF 2008 The MATHWO
60. ngth for removing remaining forces When the remaining forces are removed the robot stops again and stays in the state which is motors on ABB Robotics 2007 collision robot detected stopped residual forces time ot E N removed collis N i y Y K motor i l speed N time VL speed reversed motor torque torque reversed _ M wW Figure 4 Speed and torque diagram ABB Robotics 2007 In the ABB offline simulation and programming software RobotStudio it detect the collision between objects in the station it classify all the objects into two groups ob jects A and objects B if one object in objects A collides with one object in object B set the collision will be displayed in graphical view and logged in the output window 2 2 2 Collision detection in Microsoft Robotics Developer Studio Microsoft Robotics Developer Studio MRDS is an environment for robotics control and simulation built according to windows system It can be used in academic research people who interested in robotics and for commercial use in the robot industries It has the capacity of dealing with a wide range of robot hardware MRDS is based on Concur 2 STATE OF ART 9 rency and Coordination Runtime CCR a concurrent code library deal with asynchro nous parallel operations based on NET This technique includes utilizing message passing and a small amount of services oriented runtime It is a type of Decentralized Software
61. of robot collision detection study it is very important for robot to be able to find and avoid the collision occur the robot should be able to the detect objects and human operator which around it The problem of collision detection is typically defined as detecting the intersection of two or more objects Ericson 2005 In many robotics and computer graphics problems collision detection is used as a tool to achieve effi ciency for solving these problems For example in the movement planning collision avoidance virtual reality 3D animation computer modelling molecular modelling articulated rigid body dynamic simulation and in general all those areas related to the solids which could not access each another in the simulated motion In these applied areas collision detection appears as a functional unit or process which exchanges mes 1 INTRODUCTION sages with other parts of the system regarding movement kinematic and dynamic be haviour etc There are two distinct goals for this thesis work The first objective is to develop an approach to model the robot workcell and objects within the workcell in MATLAB This approach can be used by robot workcell designers to validate performance of the cells This approach also prepares the needed components for the collision detection analyse in the later part of this thesis The second objective is to develop a tool of colli sion detection for the robot and the working cell includes conveyors cube
62. ollision occurred the collision points is computed in the same way Gilbert 1989 2 STATE OF ART 6 2 1 4 Trajectory parameterization In this method the collision occurred time and related parameters can be found and ana lysed if the object trajectories are presented as functions of time For instance in the simple situation a point movement is a linear motion there is a triangle in the space which is not moving when the point moves if there is collision between them need to consider The parametric vector equation for the motion of the point and the triangle can be expressed as p p p t pot P1 Po ut P2 Po V 1 Where p is the initial position and p is the final position of the point Parameter p de scribe the triangle u v t are the variables u and v are parametric variables for the tri angle plane and t is a time variable which is 0 at the beginning of this process and 1 at the end In the condition if 0 lt t lt 1 AND u20 AND vz0 AND u vx1 2 Then the point intersects the triangle in the given time period this conclusion got from a research done by Moore 1988 In this parametric vector equation it can be viewed as three scalar equations in three unknowns this can be simplified into one polynomial which t is the variable 2 1 5 Gilbert Johnson Keerthi algorithm The Gilbert Johnson Keerthi GJK distance algorithm is a way of determining the distance between two objects Different from other collision
63. on StartY_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles Executes during object creation after setting all properties function StartY edit CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end function StartZ_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles Executes during object creation after setting all properties function StartZ edit CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end function SizeX_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles Executes during object creation after setting all properties function SizeX_edit_CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end 50 function SizeY_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles o Executes during object creation after setting all prope
64. or cuboid in a specific position of defined dimen sions in MATLAB The transparency of voxel also can be defined in this function For making complex shape many voxel can be used to form it This algorithm is presented here 3 APPROACH 14 Algorithm 1 Create 3D objects in MATLAB Name Create 3D objects in MATLAB Description For drawing a 3D cube shape object in a MATLAB plot the func tion voxel is used The approach used in this function is by finding a series of coordinates along x y z axes and then use patch func tion to make the cube Joel 2003 Data structures i The start point coordinates of the cube d Size of the cube in three dimensions c The colour of cube X Both the start coordinates I 1 I 2 I 3 and the size of the cube in three dimensions d 1 d 2 d 3 alpha The transparency of the cube nargin The number of function arguments Steps DO function voxel which contains variables I d c alpha 2 switch among number of function arguments 3 case the number of function arguments is 0 4 display Too few arguments for voxel 5 return 6 case nargin 1 7 the default length of side of voxel is 1 the default colour of voxel is blue 8 case nargin 2 9 then the colour of voxel is blue 10 case nargin 3 11 then the value of alpha is 1 12 case nargin 4 13 do nothing 14 otherwise 15 display Too
65. ory of my life Thank you my love Mikko for your love and care during these years thank your en couragement and support at the time when I need Last but not least thanks to my family especially thank my mother Xialing Yao who cared for me my whole life your unconditional love and support is the motive force keeps me going forward In Tampere 21 2 2012 Xiaoyun Deng II CONTENTS ABSEIBAG T 2 osi pp NI etui patto a ttu p a I IAGO AUG EM oss beo odes Spec Dn epa Dono aieo Gel oio Doo fecti Eau ide he Gean 1 2 State Of art M 3 2d BRoboteolhsiomdeteclOlis cuins ehe te pen abitanti 3 2 1 1 Approaches to collision detection Spatio temporal intersection 4 2 1 2 Swept volume IDEerferenge a eoe cete eor aSte Heras a oer ARE UN 4 2 1 3 Multiple interference detection 4 2 4 neces eae Paes 3 2 14 Trajectory parameterization erae RR 6 2 1 5 Gilbert Johnson Keerthi algorithm eeeeeeee 6 2 1 6 Tools for collision detecBOli saeecrete tete teg oreste ata 6 2 2 Collision detection in current industrial robots esses 7 2 2 1 Collision detection function in ABB robots sssss 7 2 2 2 Collision detection in Microsoft Robotics Developer Studio 8 2 2 3 Collision detection in CIROS Studio ees 9 2 2 4 Model based real time monitoring method 10 2 2 5 Deriva
66. pc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end function CenterY_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles oe Executes during object creation after setting all properties function CenterY_edit_CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end function CenterZ_edit_Callback hObject eventdata handles input guidata hObject str2double get hObject String handles o KJ Executes during object creation function CenterZ edit CreateFcn hObject eventdata if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white handles end handles function Radius_edit_Callback hObject eventdata input str2double get hObject String guidata hObject handles o KJ Executes during object creation function Radius edit CreateFcn hObject eventdata if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white handles end function Result_edit_Callback hObject guidata hObject handles
67. r inputting x axis value of sphere centre 41 get the input value and convert it to the double form 42 store the variable data in this section as GUI data 43 repeat this same action for y axis input text box and z axis input text box and also for the text box for inputting the radius of sphere 3 APPROACH 23 44 create a function for making the collision detection button 45 if the coordinates of the robot end effector in x y z axis within the cube or the sphere inserted to the robot workcell 46 display collision 47 else 48 display no collision 49 set the result to the handle object of result 50 store the variable data in this section as GUI data 3 4 Collision detection algorithm Collision detection is an important issue in robotics and computer graphical theory area appear in motion planning graphical programming control dynamic simulation virtual reality Whether a rigid body moving along a given route in touch with any of objects at any point of the route that is the collision detection problem In a wider definition of the problem should determine all the contacts In all situations it is very important that the calculation result of collision detection is accurate The result of collision detection of the objects influences the action of robot and affects the output of the simulation of ro bots like some of the result of collision will be used when design and
68. rajectory x trajectory y trajectory z bounding box x1 bounding box x2 bounding box y1 bounding box y2 bounding box z1 bounding box z2 39 From the picture above the x y z coordinates of obstacle have overlap with the trajec tories of the robot at some points at the place where robot s x y z coordinates are all within the bounding box s coordinates then the collision occurred In the figure below is a way to determine the collision point in the trajectory plot 800 T T T T T T T T trajectory x trajectory y trajectory z bounding box x1 bounding box x2 P bounding box y1 bounding box y2 bounding box z1 X 6 6 bounding box z2 c Y 149 9 B ccce RUE X BP ES 0 200 X 6 6 Y 347 8 400 Pe l 1 L l I l I 1 I 0 1 2 3 4 5 6 7 3 i time s Figure 24 Find the points which cause the collision in the trajectory plot 4 IMPLEMENTATION 40 So the collision starts at time 6 6 second the points causing collision is at coordinates x 149 9mm yz 538 5mm z 347 8mm The only drawback of this method is the accuracy it only can be accurate at 0 1mm so when the calculation once is done in the system should add some tolerance to the final result then control the robot to avoid these points in advance In this chapter an approach defined and outlined at the end of Chapter 3 is implemented and validated In the same order in the beginning is to build the models This prepares the
69. re 11 Because the features of the robot are high velocity precision and easy operation this type of robot has a wide range of usage in many fields For instance they can be used in electronic production manufacturing consumer goods and more information about Sony SRX 611 robot got from homepage of PRODEMO company In the figure 12 is a list of the specifications of this robot 4 IMPLEMENTATION 29 SRX 611 specifications Arm length Overall length 600mm No 1 arm 350mm No 2 arm 250mm Operating range No 1 arm 220 No 2 arm 150 Z axis 150mm R axis 360 Payload 2kg 3kg 5kg Cycle time with 2kg payload in the order of 0 6 sec Maximum speed with 2kg payload 1 amp 2 axes combined 5200mm sec 2 axis 770mm sec R axis 1150 Position repeatability XY plane 0 01mm Z axis 0 02mm R axis 0 03 Body Weight 35kq Tool items Signal wires 15 Air pipes 3 with outer width diameter of Figure 12 Specification of Sony SRX 611 robot SONY SRX 4 1 2 Sony SMART Cell The Sony SMART Cell is made under the standard of electronic production industry It contains operator interface conveyors safety control systems frames and can be ad justed to perform most handling or assembly task The entire cell weights 450 kg suita ble for working at 5 to 40 degree of room temperature with the maximum 90 humidi ty The right power supply for it is AC 220V 16A This robot working cell is also called Sony smart cell the Sony SRX 611 high
70. re coordinates x y z 5 create a shaded surface of sphere by the centre coordinates and the radius In step 2 it wrote as x y z sphere n this returns the coordinates of a sphere in three matrices that size are n 1 by n 1 then in step 5 draw the sphere by commanding surf or mesh The conveyor and workcell frame are created by repeating use the commands voxel and line user can define the place where is the start point of the workcell then specifying the size of the workcell And by using several cube objects the conveyor and even more complex shapes can be made in MATLAB 3 APPROACH 16 3 2 Modelling the robot by robotics toolbox in MATLAB MATLAB is widely used in the area of computer graphics linear algebra and simula tion It is usable on a very broad range of computer platforms and it is highly used in universities for studying teaching and research The fundamental functions of MATLAB can be extended by different toolboxes many of the toolboxes can be ob tained from companies or under various open source licenses The basic data types of MATLAB are vector and matrix which are very suitable for the problems in both robot ics and computer vision Corke 1996 In this thesis work the open source extension robotics toolbox for MATLAB is used for modelling robot and computing robotics pa rameters The robotics toolbox is a software package allows user to create and manipulate data types which is funda
71. rrent figure 12 get the start and end point value of the obstacle bounding box in x y z axes totally 6 values 13 plot the six values got from step 12 as 6 lines in the figure In this chapter the approach of modelling the robot workcell for collision detection is presented In the beginning the approach for modelling robot is described this is done with the robotics toolbox for MATLAB Then to build the workcell basic functions in MATLAB for constructing line cube elements are used a special function voxel is used for making cube shape objects more convenient For more complex objects like a con veyor it can be made by a combination of several cubes and lines with the basic ele ments like line and voxel they can make most objects in the robot work environment When the models of robot and workcell are built next is to make the function for colli sion detection In this approach first step is to build graphical user interface to gather all the modelling functions into the same panel then to make the real time collision detec tion function after combining modelling and collision detection functions into the same interface the collision detection tool can be realized For the next chapter the imple mentation of all the mentioned steps of this paragraph is detailed in the same order in the following chapter to derive overall implementation 28 4 IMPLEMENTATION In this chapter the implementation of the approach descr
72. rties function SizeY_edit_CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end function SizeZ_edit_Callback hObject eventdata handles input str2double get hObject String guidata hObject handles o Executes during object creation after setting all properties function SizeZ_edit_CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end Executes on button press in pushbutton7 function pushbutton7_Callback hObject eventdata handles figure 1 x y z sphere g get handles Radius_edit String size of the sphere xc get handles CenterX edit String yc get handles CenterY edit Strin zc get handles CenterZ edit Strin surf str2double xc x str2double g Str2double zc z str2double 9g guidata hObject handles r 1 lg Y 9 H coordinates of the center str2double yc y str2double 9g Qa Ou function CenterX edit Callback hObject eventdata handles input str2double get hObject String guidata hObject handles o Executes during object creation after setting all properties function CenterX edit CreateFcn hObject eventdata handles if is
73. sed for detecting the collision from out side to prevent the outside objects come to the cell A model based approach where the model can be connected to the actual workcell can be considered to be a future devel opment REFERENCES ABB Robotics 2007 Bergen 1997 Cameron 1990 Cameron 1998 CIROS 2012 Cohen 1998 Corke 1995 Corke 1996 Corke 2008 Corke 2011 43 ABB Robotics Application Manual Motion Coordination and Supervision Robot Controller RobotWare 5 0 V ster s Sweden 2007 Bergen G V D SOLID 1 0 a library for interference detec tion of three dimensional polygonal objects undergoing rigid motion http www win tue nl gino solid index1 html Ac cessed May 2012 Cameron S A Collision Detection by Four Dimensional Intersection Testing IEEE Transactions on Robotics Auto mation 1990 Cameron S Enhanced GJK algorithm University of Ox ford http www cs ox ac uk stephen cameron distances Ac cessed May 2012 CIROS Studio Company Homepage http www ciros engineering com en home Accessed May 2012 Cohen J D Gottschalk S Hudson T Pattekar A Lin M C Manocha D V COLLIDE Collision Detection for Arbitrary Polygonal Objects http gamma cs unc edu V COLLIDE Accessed May 2012 Corke P L A computer tool for simulation and analysis the Robotics Toolbox for MATLAB Proceedings of the 1995 National Conference of the
74. shing the button and the other edit box will display the result of the robot collision situation The algorithm for this is presented in algorithm 4 Algorithm 4 Model of collision detection interface Name Model of collision detection interface Description This algorithm is for making a basic model of collision detection graphical user interface it defines the properties and behaviours of all components of the GUI window when user executes the file it creates a figure window with one input box one output box and one push button Steps 1 function name is GULM 2 make a figure for the frame of this GUI define position size and name 3 create user interface control object for first edit box this in cludes define position and number of lines in this edit box value type font weight horizontal align font size 4 create user interface control object for the second edit box this includes define position and number of lines in this edit box value type font weight horizontal align font size 5 create user interface control for push button this include define the units position horizontal align type of word to dis play font size callback it calls the function pb_call 6 give the first edit box controllability 7 function pb_call varargin 8 get the string from edit box and give it to variable w 9 set initial position value ql w 10 create link obj
75. stomer s special requirement The basic modules contain mechanics electronics and geometry modelling module a 3D tool for making models in real time controller simulation module and the standard ro bot programming language a tool for managing programs and position lists for robot a library of basic models a support system includes tutorials and a few other features make CIROS Studio easier to use CIROS 2012 2 STATE OF ART 10 In CIROS Studio the collision problems can be checked during the simulation process The collision detection function is included in the simulation module once the simula tion menu in the user interface is selected user can active the sensor and collision detec tion function When the collision detection user interface opened in the index card which name is selection all the objects name will be shown there user can choose many of them to see if they have collision by selecting the selected object against each other option CIROS 2012 2 2 4 Model based real time monitoring method For detecting final external collision this method uses a model based real time virtual simulator of industrial robot The applied method involves model based error detection and separation used to find information about lock of movement from an activated ro bot joint after contact with still obstacles also online implementation of this method has been tested from a research work of Fawaz 2009 In order to detect and ident
76. structure guidata hObject handles oo Outputs from this function are returned to the command line function varargout MyAdderShapeGUI OutputFcn hObject eventdata handles varargout cell array for returning output args see VARARGOUT hObject handle to figure eventdata reserved to be defined in a future version of MATLAB handles structure with handles and user data see GUIDATA Get default command line output from handles structure varargout 1 handles output Executes on button press in frame pushbutton function frame pushbutton Callback hObject eventdata handles hObject handle to frame pushbutton see GCBO figure 1 frame voxel 700 700 900 1400 1400 2450 0 7 0 7 0 7 0 2 Stop voxel 700 700 1500 1400 1400 30 0 9 0 9 0 9 0 0 Supper part buttom layer voxel 700 700 930 1400 1400 30 0 7 0 7 0 7 0 2 Smiddle layer voxel 700 700 900 1400 1400 450 0 7 0 7 0 7 0 0 48 voxel 700 700 450 1400 1400 30 0 7 0 7 0 7 0 0 Sbase voxel 500 400 1650 1000 1050 720 0 9 0 9 0 9 1 0 Slines line 15 15 700 700 420 1500 color k line 15 15 700 700 420 1500 color k line T700 700 15 215 420 1500 1 eodor tE lznec T00 700 15 19 gt 1 420 1500 eelor kY line 700 700 15 15
77. t voxel 500 700 900 100 300 100 0 5 0 5 0 5 0 9 voxel 400 700 900 100 300 100 0 5 0 5 0 5 0 9 voxel 300 700 900 100 300 100 0 5 0 5 0 5 0 9 voxel 400 700 900 100 300 100 0 5 0 5 0 5 0 9 guidata hObject handles Executes on button press in addRobot pushbutton function addRobot pushbutton Callback hObject eventdata handles hObject handle to addRobot pushbutton see GCBO 11 link 0 350 0 50 0 standard 12 link 0 250 0 0 0 standard 13 link 00 0 720 1 standard 14 link 000 300 0 standard gqinput 1 885 0 062832 0 1885 0 75398 rob robot 11 12 13 14 49 figure 1 plot rob qInput hold on Saxisi 1500 1500 1500 1500 1500 1500 Sdrivebot rob guidata hObject handles oo Executes on button press in RemoveFrame pushbutton function RemoveFrame pushbutton Callback hObject eventdata handles delete figure 1 figure 2 guidata hObject handles function StartX edit Callback hObject eventdata handles input str2double get hObject String guidata hObject handles oo Executes during object creation after setting all properties function StartX edit CreateFcn hObject eventdata handles if ispc amp amp isequal get hObject BackgroundColor get 0 defaultUicontrolBackgroundColor set hObject BackgroundColor white end functi
78. tial interface is shown in the picture below f GULM ems 1 885 0 062832 0 1885 0 7 No Collision Input Position Figure 20 Initial GUI for detecting collision After the interface above is made more requirements are considered One requirement is this interface should be able to load robot and workcell components And when insert some object to the workcell user can define the location and the size of the objects The appearance of this interface is shown in the picture below all the push buttons in this interface is for generating components beside the clear all button is for removing all the created objects The input boxes are made for user to define the coordinates and size of the cube and sphere objects 4 IMPLEMENTATION 38 Bl MyAdderShapeGUI ere Tess Add Shapes to Robot Cell Load Robot Add Cube Start from Add Frame x ve z Size Add Production Line os M z f Center Generate Sphere x A zj Radius Clear All sid Figure 21 Third stage of GUI development When the interface above is made one more requirement is considered this interface should be able to detect collision so the collision detection function area is created in it When user clicks the get result button it will determine collision situation and give out put message in the edit box next to the get result button The user start to run the My AdderShapeGUI m file
79. tion of kinematic parameters method 10 2 2 6 Other robot modelling methods eene 11 Dy Approach ee BeBe E 13 3 1 Creating 3D objects and workcell in MATLAB een 13 3 2 Modelling the robot by robotics toolbox in MATLAB 16 3 3 Graphical user interface for collision detection sess 17 3 3 1 Basic model of collision detection user interface 18 3 3 2 Collision detection interface oco esie oed st ated rode diens 19 3 4 Collision detection algorithm sees enne 23 3 5 Trajectory planning for collision detection see 26 4 Implementation onore or eeu tur Sonde a toe ie aai qui MUS 28 4T Dherobotand workcell se etesddteses trono e o toa dude o Nube quer 28 4 1 1 Sony SRX 611 High Speed Assembly Robot 28 41 2 Sony SMART COM s a E des tt ah 20 4 2 Define and model the FONG uoc o tottatep ui tte et teehee 30 4 3 Rough model of the robot workcell eene 31 4 4 Collision detection for rough model of robot workcell 32 4 5 SD objects in the WOrkCell sc austesstoscsmetts Gestazie oce tsastota Sedis ies 33 4 6 General function for collision detection 33 4 7 Detect the collision in real Desi oes tasti ebat iden dust Pec opea e deed 35 4 9 Model the
80. tors toolbox with symbolic dynamics Symbolic dynam ics can be used to execute analysis and design studies on any mechanical system which can be modelled as a set of rigid bodies connected by joints affected by forces driven by defined motions and limited by constraints Hollars 1994 The dynamic model is shown in figure 9 Int_qdd Dyn Mod F grae Figure 9 Dynamic model made by planar manipulators toolbox Hollars 1994 After reviewing many of the modelling approaches and collision detection tools in this chapter it shows that each approach has their own advantages and disadvantages and some of them are complex An approach can be suggested to simplify robot workcell modelling for collision detection this approach is presented in the Chapter 3 13 3 APPROACH In this chapter the approach of modelling robot and workcell developing the collision detection tool is presented This chapter is arranged in the order First is the approach for modelling 3D objects robot and workcell in MATLAB After these sections is the creating of collision detection tool this includes the development of collision detection algorithm In the end of this chapter is the trajectory planning approach for collision detection 3 1 Creating 3D objects and workcell in MATLAB 3D modelling in the computer graphics field is defined as a technique of building math ematical representation for 3D physical objects by particular software Liu 2010
81. ts working environment Two main collision detection approaches are presented one is based on the distance calcula tion between the robot and the obstacle the second one consists on analysing the trajec tory of both the robot and the obstacle For controlling purposes several graphical user interfaces have been developed in order to make the controlling process and the reading of the collision results clear for the user PREFACE This Master s thesis is done in FAST laboratory of production engineering department at Tampere University of Technology In the thesis the robot workcell modelling ap proach and the collision detection tool have been explored During the process of mak ing this thesis I have received help and support from many people I would express my gratitude to them all I would like to thank Associate Professor Andrei Lobov for giving me the opportunity to work on this subject and for the guidance during the entire thesis work Especially when some problem occurred he gave me very helpful suggestions Thanks Professor Martinez Lastra for giving me the chance to join the FAST laboratory working environment provide me the equipment for doing my experiments his super vision and cares also gave me much motivation Thanks to Xiaochen and Dazhuang your sincere friendship gave me much support dur ing my studies thanks to all other friends in Tampere University of Technology you made my days at TUT an unforgettable mem

XIAOYUN DENG ROBOT WORKCELL MODELLING AND

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