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  1. 33rd Annual Simulationsymposium ANSS2000, April 16-20, 2000. Washington, D.CSamir OtmaneE-mail : otmane@cemif.univ-evry.fr CEMIF, Laboratoire Systèmes ComplexesHttp : http://lsc.cemif.univ-evry.fr:8080/~otmane 40 Rue du Pelvoux 91020 Evry, France Tél : 01/69/47/75/04 Fax : 01/69/47/75/99 Active Virtual Guides as an Apparatus for Augmented Reality Based Telemanipulation System on the Internet

  2. Contents • Introduction • ARITI System • Virtual guides/fixtures • Unified Formalism • Simple and Complex Virtual fixtures • Virtual guides representation • Manipulation on the screen • Deforming guides to generate an appropriate guides • Experiments and Results • Conclusion and perspectives

  3. Introduction- Tele-work - Master site Communication support Slave site • The slave site is distant from the master site. • Information feedback is corrupted by a bandwidth limitation of communication support . • Time delay is not constant when using any communication network. • No portable and user-friendly Tele-work systems. • Human performances are decreased during direct control of remote Tele-manipulation task. Information feedback Sending orders

  4. ARITI system • Virtual reality and Augmented Reality technologies are used to : • Overcome the instability of time delay, • Complete or compensate the information feedback (video feedback for instance) • JAVA programming Language is used to implement the Man Machine Interface of ARITI system to : • Give a portable system and • User-friendly Tele-work system

  5. Interaction between Human and remote Task Environment • During interaction control of a remote robotic terminal tool, the user must • Perform a physical action to initiate motion from the robot, • Wait for the system to respond, • Perceive the physical effect onto the robot and task environment, • Decide what to do next, • Repeat the cycle until the task is completed. • Motor activity is initiated through interaction with a software interface via Keyboard and mouse, joystick, master arm, etc... N E T W SOFT HARD Human Operator Robotic Interface Remote Robotic Environment

  6. Interactions withA R I T I • Three kinds of visual assistance are given to human operator for friendly human computer interaction using the ARITI interface. These visual helps are devoted to : • Environment perception • Robot control • Robot supervision Perception N E T W HARD Remote Environment Human Operator Control Supervision Robotic Interface

  7. Assistance for EnvironmentPerception Several Virtual view points + Human Operator Video image feedback Perception module In Control module

  8. Assistance for RobotSupervision Textual information of the current task + Human Operator Overlaid Model / Image Supervision module

  9. Assistance for Robot Control Human Operator(HO) Virtual robot Control module In Supervision module

  10. System descriptionHardware • ARITI system is implemented on a PC Pentium 233 Mhz with a 128 Mo RAM. • The PC is equipped with a Matrox Meteor video acquisition card connected to a black and white camera. • The orders are sent via the RS232 serial link. Video acquisition Orders RS232 serial link

  11. System descriptionSoftware • ARITI system is implemented under LINUX operating system. • ARITI interface is written based on JAVA object programming language • Video server is written using the C standard language. • Control server is written using the C and ASM (Microprocessor Assembly Language ) S O K E T Video Client Video server -ARITI- INTERFACE Control Client Control server Applet JAVA C and ASM L I N U X - O S -

  12. To use the ARITI system WWW CLIENTS + Internet Browser A R I T I System Camera Robot

  13. The ARITI Displayhttp://lsc.cemif.univ-evry.fr:8080/Projets/ARITI

  14. Question !! How to increase Human Operator performances to do Telemanipulation task very easier ?

  15. Increase Assistance for Robot Control Virtual robot + Human Operator Virtual Fixtures Control module In Supervision module

  16. Virtual Fixtures Structure

  17. Simple Virtual Fixtures • Human operator can create and use virtual fixtures to control the robot very easier. • Some examples of simple Virtual Fixtures (VF) : Disc Sphere Plan Super-ellipsoid Cone Cube or Square Cylinder Pipe

  18. Complex Virtual Fixtures Delimiting the workspace between two robots in cooperation Following an arbitrary trajectory by the robot Reaching a dangerous target with the robot end tool

  19. Method of construction • taking some significant points on the surface of the guide • joining these points in order to get a wire frame representation • Example : • If a parametric equation of the guide is : with • Then the vertexs are : • And the segments are :

  20. Manipulation onthe screen • Use of the graphic camera model • Is the matrix M which transform point coordinates (Xo, Yo, Zo ) In the referential Ro, onto the screen point coordinates (U, V) .

  21. Selection of the 3D Fixtures on the screen • The designation on the screen = 2D point (U, V) • Determining what object 3D wanted to designate • The designated point belongs to a D segment, witch equation is :

  22. Selection of the 3D Fixtures on the screen • Determining what vertex on the 3D objects having the smallest distance from the line segment D. Selected fixture Screen Selected point

  23. DeformingVirtual Fixtures • Each virtual fixtureis associated to a graph where X is a set of vertexs, and U a set of lines . • We define an application V which associates any vertex x in X a set of his neighbors : • We call a distance between the vertex x and y.

  24. DeformingVirtual Fixtures • If x0is a start point of deformation and • 0 the value of this deformation, • Then the value of deformation of the fixture is given by : • Where p is called initial propagation factor • and f is called the dissipation of propagation factor

  25. DeformingVirtual Fixtures P = 0.99, f = 0.99 P = 0.99, f = 0.9 P = 0.99, f = 0.9

  26. Experiments • Pick and place task • Tele-operation mode • Control the real robot via the virtual robot • 10 human operators (HO) • 3 kinds of test • Without Virtual Fixtures • With passiveVirtual Fixtures • With active (attractive) Virtual Fixtures • Each HO makes 10 tests for each kind

  27. Experiments Task Board • The robot is assumed to assemble (place) and disassemble (pick) objects hanging on a metal stand Target Objects Head of the robot peg Metal stand

  28. Fixture to reacha target • A simple geometric primitive : • Cone .

  29. Fixture to pick theobject and unhook it • A complex Virtual guide • Combining a 3 simple guides (cylinders)

  30. Fixture to place the object onto the stand • A complex Virtual guide • Combining 4 simple guides ( 1 cone + 3 cylinders)

  31. ResultsReach a cylinder N° 1 • Reach a 3D target point on the peripheral of the cylinder N°1 • Without virtual fixtures there is 1.49 collision for each test

  32. ResultsReach a cylinder N° 1 Average time 7,7 sec with active VFs Imprecision errors on X, Y, Z axis Err < 0,25 mm with active VFs

  33. Results Pick and place a cylinder N° 1 • - Blue - with passive VFs. • - Red - with active (attractive potential fields) VFs. Unhook a cylinder N° 1 Passive VFs - 12,78 sec Active VFs - 9,5 sec Place a cylinder into the stand, Passive VFs - 37,96 sec Active VFs - 7,86 sec

  34. Conclusion • Thanks to Virtual Fixtures the human operator performances are increased : • best accuracy < 0,25 mm • best completion time • best safety • JAVA programming Language is used to implement these Virtual Fixtures into the ARITI system to : • Give a portable and interactive fixtures.

  35. Perspectives • Use the Virtual Fixtures for mobile robot application, such as • Navigation, obstacles avoidance, to assist disable person.

  36. Perspectives • Add Tactile functions to activate fixtures • Extend the use of virtual fixtures to do a cooperative Tele-Work User 1 Robot 1 User 2 N E T Robot 2 . . . Extended A R I T I System . . . User n Robot m

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