Robot force control

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机器人力控制

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Robot force control

  1. 1. Introduction Lorenzo Sciavicco Motion control Bruno Siciliano Indirect force control Luigi Villani Direct force control Stefano Chiaverini Experiments Bruno Siciliano Hybrid force control and contact estimation in the task frame formalism Herman Bruyninckx
  2. 2. Research @ PRISMA Lab <ul><li>Dual-robot system </li></ul><ul><ul><li>Redundancy resolution </li></ul></ul><ul><ul><li>Singularity robustness </li></ul></ul><ul><ul><li>Cooperative tasks </li></ul></ul><ul><ul><li>Fault tolerance </li></ul></ul><ul><ul><li>Model identification </li></ul></ul><ul><ul><li>Inverse dynamics control </li></ul></ul><ul><ul><li>Force control </li></ul></ul><ul><ul><li>Visual tracking </li></ul></ul><ul><ul><ul><ul><li>Interaction control </li></ul></ul></ul></ul>
  3. 3. Robot Force Control Introduction Lorenzo SCIAVICCO Dipartimento di Informatica e Automazione Università degli Studi di Roma Tre [email_address]
  4. 4. Outline <ul><li>Force control </li></ul><ul><ul><li>Motion control vs. interaction control </li></ul></ul><ul><ul><li>Indirect vs. direct force control </li></ul></ul><ul><li>Modelling </li></ul><ul><ul><li>Kinematics </li></ul></ul><ul><ul><li>Dynamics </li></ul></ul><ul><li>Control Strategy </li></ul><ul><ul><li>Joint space control vs. task space control </li></ul></ul>
  5. 5. Force control <ul><li>Motion control vs. interaction control </li></ul><ul><ul><li>Object manipulation or surface operation requires control of interaction between robot manipulator and environment </li></ul></ul><ul><ul><li>Use of purely motion control strategy is candidate to fail (task planning accuracy) </li></ul></ul><ul><ul><li>Control of contact force (compliant behaviour) </li></ul></ul><ul><ul><li>Use of force/torque sensor (interfaced with robot control unit) </li></ul></ul><ul><li>Indirect vs. direct force control </li></ul><ul><ul><li>Indirect force control: force control via motion control (w/out explicit closure of force feedback loop) </li></ul></ul><ul><ul><li>Direct force control: force controlled to desired value (w/ closure of force feedback loop) </li></ul></ul>
  6. 6. Modelling <ul><li>Kinematics </li></ul><ul><ul><li>Kinematic model </li></ul></ul>
  7. 7. Modelling (cont’d) <ul><ul><li>Differential kinematics </li></ul></ul><ul><ul><li>task variables </li></ul></ul><ul><ul><li>: kinematic redundancy </li></ul></ul>: matrix geometric Jacobian kinematic singularities (!)
  8. 8. Modelling (cont’d) <ul><li>Dynamics </li></ul><ul><ul><li>Lagrange formulation </li></ul></ul><ul><ul><li>Dynamic model </li></ul></ul>
  9. 9. Modelling (cont’d) <ul><ul><li>Skew-symmetry of </li></ul></ul><ul><ul><li>Hamilton principle </li></ul></ul><ul><ul><li>Linearity in the dynamic parameters </li></ul></ul>
  10. 10. Control strategy <ul><li>Joint space control </li></ul><ul><ul><li>Task references transformed into joint references </li></ul></ul><ul><ul><li>Redundancy resolution at kinematic level </li></ul></ul>
  11. 11. Control strategy (cont’d) <ul><li>Task space control </li></ul><ul><ul><li>Control directly in task (operational) space </li></ul></ul><ul><ul><li>Redundancy resolution at dynamic level </li></ul></ul>
  12. 12. Robot Force Control Motion control Bruno SICILIANO Dipartimento di Ingegneria dell’Informazione e Ingegneria Elettrica Università degli Studi di Salerno [email_address]
  13. 13. Outline <ul><li>Tracking control </li></ul><ul><ul><li>Dynamic model-based compensation </li></ul></ul><ul><ul><li>Euler angles error </li></ul></ul><ul><ul><li>Angle/axis error </li></ul></ul><ul><ul><li>Quaternion error </li></ul></ul><ul><ul><li>Computational issues </li></ul></ul><ul><ul><li>Redundancy resolution </li></ul></ul><ul><li>Regulation </li></ul><ul><ul><li>Static model-based compensation </li></ul></ul><ul><ul><li>Orientation errors </li></ul></ul>
  14. 14. Tracking Control <ul><li>Dynamic model-based compensation </li></ul><ul><ul><li>Position control </li></ul></ul><ul><ul><li>Orientation control </li></ul></ul>Euler angles Angle/axis Quaternion
  15. 15. Tracking Control (cont’d) <ul><li>Euler angles error: </li></ul><ul><ul><li>Resolved angular acceleration </li></ul></ul><ul><ul><li>Error dynamics </li></ul></ul>representation singularities (!)
  16. 16. Tracking Control (cont’d) <ul><li>Alternative Euler angles error: </li></ul><ul><ul><li>Resolved angular acceleration </li></ul></ul><ul><ul><li>Error dynamics </li></ul></ul>choose so that is nonsingular (!)
  17. 17. Tracking Control (cont’d) <ul><li>Angle/axis error: </li></ul>Simple rotation Rodrigues parameters Quaternion Classical angle/axis Representation
  18. 18. Tracking Control (cont’d) <ul><li>Angle/axis error: </li></ul><ul><ul><li>Resolved angular acceleration </li></ul></ul><ul><ul><li>Error dynamics </li></ul></ul>
  19. 19. Tracking Control (cont’d) <ul><ul><li>Simpler choice: </li></ul></ul><ul><ul><li>Error dynamics </li></ul></ul>… stability via Lyapunov argument ( )
  20. 20. Tracking Control (cont’d) <ul><li>Quaternion error: </li></ul><ul><ul><li>Resolved angular acceleration </li></ul></ul><ul><ul><li>Error dynamics </li></ul></ul>… stability via Lyapunov argument
  21. 21. Tracking Control (cont’d) <ul><li>Computational issues </li></ul>1 0 8 8 Funcs 60 55 136 68 Flops Resolved acceleration 1 0 0 8 Funcs 21 0 0 52 Flops Trajectory generation Quaternion Angle/axis Alternative Euler angles Classical Euler angles Orientation error
  22. 22. Tracking Control (cont’d) <ul><ul><li>Comparison </li></ul></ul>Large errors Computational load Repres. singularities Similar to position Pros Nonlinear error dyn. Sing.-free trajectory Computational load Large errors Computational load Repres. singularities Cons Quaternion Angle/axis Alternative Euler angles Classical Euler angles Orientation error
  23. 23. Tracking Control (cont’d) <ul><li>Redundancy resolution </li></ul>dynamically consistent pseudo-inverse … stability via Lyapunov argument
  24. 24. Tracking Control (cont’d) <ul><ul><li>Inverse dynamics control with redundancy resolution </li></ul></ul>
  25. 25. Regulation <ul><li>Static model-based compensation </li></ul><ul><ul><li>Position control </li></ul></ul><ul><ul><li>Orientation control </li></ul></ul><ul><ul><li> </li></ul></ul>Euler angles Angle/axis Quaternion
  26. 26. Regulation (cont’d) <ul><li>Orientation errors </li></ul><ul><ul><li>Euler angles </li></ul></ul><ul><ul><li>Alternative Euler angles </li></ul></ul><ul><ul><li>Angle/axis </li></ul></ul><ul><ul><li>Quaternion </li></ul></ul>for all … stability via Lyapunov argument
  27. 27. Robot Force Control A.D. MCCXXIV Indirect force control Luigi VILLANI Dipartimento di Informatica e Sistemistica Università degli Studi di Napoli Federico II [email_address]
  28. 28. Outline <ul><li>Compliance control </li></ul><ul><ul><li>Active compliance </li></ul></ul><ul><li>Impedance control </li></ul><ul><ul><li>Active impedance </li></ul></ul><ul><ul><li>Inner motion control </li></ul></ul><ul><ul><li>Three-DOF impedance control </li></ul></ul><ul><ul><li>Six-DOF impedance control </li></ul></ul>A.D. MCCXXIV
  29. 29. Compliance control <ul><li>Active compliance </li></ul><ul><ul><ul><li>… at steady state (position/force) </li></ul></ul></ul>A.D. MCCXXIV
  30. 30. Impedance control <ul><li>Active impedance </li></ul>force/torque sensor A.D. MCCXXIV
  31. 31. Impedance control (cont’d) <ul><ul><li>Impedance control (w/ force/torque measurements) </li></ul></ul>A.D. MCCXXIV
  32. 32. Impedance control (cont’d) <ul><li>Inner motion control </li></ul><ul><ul><li>Enhanced disturbance rejection </li></ul></ul>compliant frame A.D. MCCXXIV
  33. 33. Impedance control (cont’d) <ul><li>Three-DOF impedance control </li></ul><ul><ul><li>Translational impedance </li></ul></ul><ul><ul><li>Linear acceleration (inner motion loop) </li></ul></ul>A.D. MCCXXIV
  34. 34. Impedance control (cont’d) <ul><li>Six-DOF impedance control </li></ul><ul><ul><li>Rotational impedance (Euler angles) </li></ul></ul><ul><ul><li>Infinitesimal orientation displacement </li></ul></ul><ul><ul><li>Angular acceleration (inner motion loop) </li></ul></ul>task geometric inconsistency A.D. MCCXXIV
  35. 35. Impedance control (cont’d) <ul><ul><li>Rotational impedance (alternative Euler angles) </li></ul></ul><ul><ul><li>Infinitesimal orientation displacement </li></ul></ul><ul><ul><li>Angular acceleration (inner motion loop) </li></ul></ul>task geometric consistency (XYZ Euler angles + diagonal stiffness) A.D. MCCXXIV
  36. 36. Impedance control (cont’d) <ul><ul><li>Rotational impedance (angle/axis) </li></ul></ul><ul><ul><li>Infinitesimal orientation displacement </li></ul></ul><ul><ul><li>Angular acceleration (inner motion loop) </li></ul></ul>task geometric consistency A.D. MCCXXIV
  37. 37. Impedance control (cont’d) <ul><ul><li>Rotational impedance (quaternion) </li></ul></ul><ul><ul><li>Infinitesimal orientation displacement </li></ul></ul><ul><ul><li>Angular acceleration (inner motion loop) </li></ul></ul>task geometric consistency A.D. MCCXXIV
  38. 38. Robot Force Control Direct force control Stefano CHIAVERINI Dipartimento di Automazione, Elettromagnetismo, Ingegneria dell’Informazione e Matematica Industriale Università degli Studi di Cassino [email_address]
  39. 39. Outline <ul><li>Force regulation </li></ul><ul><ul><li>Static model-based compensation </li></ul></ul><ul><ul><li>Dynamic model-based compensation </li></ul></ul><ul><li>Force/motion control </li></ul><ul><ul><li>Force and position regulation </li></ul></ul><ul><ul><li>Force and position control </li></ul></ul><ul><ul><li>Moment and orientation control </li></ul></ul><ul><ul><li>Force tracking </li></ul></ul>
  40. 40. Force regulation <ul><li>Static model-based compensation </li></ul><ul><ul><li>PI control </li></ul></ul><ul><ul><li>… at steady state </li></ul></ul>
  41. 41. Force regulation (cont’d) <ul><li>Dynamic model-based compensation </li></ul><ul><ul><li>Force and moment control with inner motion control loop </li></ul></ul>
  42. 42. Force/motion control <ul><li>Force and motion control </li></ul><ul><ul><li>Regulation of force but loss of motion control </li></ul></ul><ul><ul><li>Recover motion control along unconstrained directions while ensuring force control along constrained directions </li></ul></ul>parallel control strategy
  43. 43. Force/motion control (cont’d) <ul><li>Force and position regulation </li></ul><ul><ul><li>At steady state </li></ul></ul>
  44. 44. Force/motion control (cont’d) <ul><li>Force and position control </li></ul>
  45. 45. Force/motion control (cont’d) <ul><ul><li>Force and position control with full parallel composition </li></ul></ul>
  46. 46. Force/motion control (cont’d) <ul><li>Moment and orientation control </li></ul>
  47. 47. Force/motion control (cont’d) <ul><li>Force tracking </li></ul><ul><ul><li>Full parallel composition </li></ul></ul><ul><ul><li>Time-varying force </li></ul></ul><ul><ul><li> </li></ul></ul><ul><ul><li>tracking if exactly known </li></ul></ul>
  48. 48. Force/motion control (cont’d) <ul><ul><li>Contact stiffness adaptation ( ) </li></ul></ul><ul><ul><li> </li></ul></ul>
  49. 49. Experiments <ul><li>Set-up </li></ul><ul><ul><li>COMAU Smart 3-S robot </li></ul></ul><ul><ul><li>Open control architecture </li></ul></ul><ul><ul><li>ATI force/torque sensor </li></ul></ul><ul><li>Force-motion control </li></ul><ul><ul><li>Compliance control </li></ul></ul><ul><ul><li>Impedance control </li></ul></ul><ul><ul><li>Force control </li></ul></ul><ul><ul><li>Parallel control </li></ul></ul><ul><ul><li>Hybrid control </li></ul></ul>
  50. 50. Experiments (cont’d) <ul><li>Impedance control </li></ul><ul><ul><li>Contact with unknown surface </li></ul></ul><ul><ul><li>Accommodation of both force and moment </li></ul></ul><ul><ul><li>Geometric consistency </li></ul></ul>
  51. 51. Experiments (cont’d) <ul><li>Extension to dual-robot system </li></ul><ul><ul><li>typical peg-in-hole assembly task </li></ul></ul><ul><ul><li>robot holding the hole controlled as 6-DOF impedance </li></ul></ul><ul><ul><li>robot holding the peg programmed in PDL-2 </li></ul></ul><ul><ul><li>accommodation of misalignment and overshoot </li></ul></ul>
  52. 52. Further experiments <ul><li>Set-up @ ARTS Lab, SSSA Pisa </li></ul><ul><ul><li>DEXTER cable-actuated robot arm </li></ul></ul><ul><li>Compliance control </li></ul><ul><ul><li>tasks of assisting disabled people </li></ul></ul>
  53. 53. Further experiments (cont’d) <ul><li>Set-up @ DLR, Germany </li></ul><ul><ul><li>KUKA robot with force sensor and camera embedded in the gripper </li></ul></ul><ul><li>Integration of vision and force </li></ul><ul><ul><li>visual feedback in gross motion </li></ul></ul><ul><ul><li>force feedback in fine motion </li></ul></ul>
  54. 54. References <ul><li>F. Caccavale, C. Natale, B. Siciliano, L. Villani, &quot;Resolved-acceleration control of robot manipulators: A critical review with experiments&quot;, Robotica , 16, 565–573, 1998 </li></ul><ul><li>F. Caccavale, C. Natale, B. Siciliano, L. Villani, &quot;Six-DOF impedance control based on angle/axis representations&quot;, IEEE Transactions on Robotics and Automation , 15, 289–300, 1999 </li></ul><ul><li>F. Caccavale, C. Natale, B. Siciliano, L. Villani, &quot;Achieving a cooperative behaviour in a dual-arm robot system via a modular control structure&quot;, Journal of Robotic Systems , 18, 691–700, 2001 </li></ul><ul><li>F. Caccavale, B. Siciliano, L. Villani, &quot;Robot impedance control with nondiagonal stiffness&quot;, IEEE Transactions on Automatic Control , 44, 1943–1946, 1999 </li></ul>
  55. 55. References (cont’d) <ul><li>S. Chiaverini, L. Sciavicco, &quot;The parallel approach to force/position control of robotic manipulators&quot;, IEEE Transactions on Robotics and Automation , 9, 361–373, 1993 </li></ul><ul><li>S. Chiaverini, B. Siciliano, L. Villani, &quot;Force/position regulation of compliant robot manipulators&quot;, IEEE Transactions on Automatic Control , 39, 647–652, 1994 </li></ul><ul><li>S. Chiaverini, B. Siciliano, L. Villani, &quot;A survey of robot interaction control schemes with experimental comparison&quot;, IEEE/ASME Transactions on Mechatronics , 4, 273–285, 1999 </li></ul><ul><li>C. Natale, Interaction Control of Robot Manipulators: Six-degrees-of-freedom Tasks , Springer, Heidelberg, Germany, 2003 </li></ul><ul><li>B. Siciliano, L. Villani, Robot Force Control , Kluwer, Boston, MA, 1999 </li></ul>

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