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Stable rendering methods for Haptic interaction
- 1. A STUDY ON STABLE HAPTIC RENDERING METHODS USING FPGA Student: Trung Hieu Do Advisor: Jee-Hwan Ryu BioRobotics Lab. School of ME - Korea University of Technology and Education
- 2. Contents Haptic Interfaces and Stability Analysis Review of the Time Domain Passivity Approach Proposed Methods Memory-based Method Multi-rate TDPA Method Experimental Setup Conclusions & Future works References
- 3. Haptic Interfaces & Stability Analysis
- 4. Overview of Haptic Interfaces Assumption: Virtual Objects are Static & Passive Master Device Human Operator Computer-based VE Slow update rate N. Diolaiti, G. Niemeyer, F. Barbagli, J. Kenneth Salisbury, Jr, ”Stability of Haptic Rendering: Discreatization, Quantization, Time-Delay and Coulomb Effects,” IEEE Transactions on Robotics , 22(2): pp. 256-268, April 2006. Human Operator Computer-based VE Slow update rate Embedded Haptic Controller Fast update rate 10-100 Hz 1-10kHz Master Device
- 5. Zero Order Hold & The Effect of Discretization Analog
- 6. Unstable Behavior of Haptic Interface
- 7. Review of the Time Domain Passivity Approach
- 8. Time Domain Passivity Approach Passivity Observer (PO): Passivity Controller (PC): TDPA Human Operator Master Device Computer-based VE PC PO 10-100 Hz
- 9. Ideal Behavior of TPDA Method
- 10. Block Diagram Conventional TDPA method PO Update PO PC Clock signal Reset PO Conv. TDPA Stability Controller Update PC
- 11. Noisy Behavior of Conventional TDPA J-H. Ryu, B. Hannaford, D-S. Kwon, and J-H. Kim, “A Simulation/Experimental Study of the Noisy Behavior of the Time Domain Passivity Controller,” IEEE Trans. on Robotics , Vol. 21, No. 4, pp. 733-741.
- 12. Noisy Behavior of Conv. TDPA
- 13. Block Diagram FPGA-based TDPA PO Update PO PC Reset PO FPGA-based TDPA Stability Controller Motion Detector Update PC Reset PO Irregular activating method Increase activating speed of PC Reduce generated energy B. Han, J-H. Ryu “An Injecting Method of Physical Damping to Haptic Interfaces Based on FPGA,” Proceedings of the International Conference on Control, Automation and Systems (ICCAS 2008) , Seoul, Korea, pp. 1835-1840.
- 14. Stable Behavior FPGA-based TDPA
- 15. Noisy Behavior in Stiffer VE
- 16. Memory-based method Proposed methods
- 17. Idea of Memory-based Method Memorize the pressing forces Use pressing forces as boundaries for releasing forces VE characteristics changes when releasing. However Pressing period is more important for human feeling. Pressing Releasing Position
- 18. Block Diagram Memory-based Method Select Switch Data Address R/W Memory Direction Detector Memory-based method Stability Controller
- 19. Stable Behavior Memory-based Method
- 20. Slow Interaction Behavior Memory-based method
- 21. Proposed Methods Multi-rate TDPA method
- 22. Multi-rate Haptic Computer-based VE 0.1kHz Multi-rate Haptic Controller 10kHz 10kHz sample rate Master device FPGA Human Operator Analog 0.1kHz sample rate
- 23. Multi-rate Haptic Interpolation Method M. C. Cavusoglu and F. Tendick, "Multirate Simulation for High Fidelity Haptic Interaction with Deformable Objects in Virtual Environments," in Proceedings of the IEEE International Conference on Robotics and Automation , 2000, pp. 2458-2465. F(t)
- 24. Behavior of Multi-rate Haptic Fm[N]
- 25. Activity of Multi-rate Haptic Interface Active period Passive period
- 26. Activity of Multi-rate Haptic Multi-rate haptic can’t guarantee Stability TDPA method Generated energy:
- 27. Multi-rate TDPA Computer-based VE 0.1kHz Multi-rate Force estimator 10kHz Time Domain Passivity Controller 10kHz Human Operator FPGA Master device
- 28. Block Diagram of Multi-rate TDPA FPGA-based Haptic Controller Force interpolator PC-based VE Down sample Encoder reader Multi-rate TDPA Stability Controller Conv.TDPA or event-based TDPA
- 29. Dissipitation of Generated Energy PC activated
- 30. Stability of Multi-rate TDPA
- 31. Slow Interaction of Multi-rate TDPA
- 33. Haptic System Human operator Motor driver Mechanical interface Master Device FPGA-Based Haptic Controller PC-based VE Physical interaction Virtual Interaction
- 34. Software Architecture Parrallel, complicated, flexible, high-speed and simultaneous tasks The necessity of FPGA technology. A DSP/MCU-based system is possible but difficult to realize. Stability Controller PC-based VE 0.1kHz PI Current Controller 50kHz Position counter Elapsed timer Direction detector Encoder reader A phase B phase Position PWM output Measured force (current) FPGA-based haptic controller PWM generator FIFO data acquisition 5 kHz TCP/IP
- 35. Conclusions & Future Works
- 36. Maximum VE Stiffness VE
- 37. Conclusions Methods Features FPGA-based TDPA Memory-based Multi-rate TDPA Performance Worst performance Better performance Best performance Range of impedance Lowest max. stiffness Higher max.stiffness Highest max.stiffness Noise behavior Noise behavior Less noise behavior Least noise behavior Distortion (VE) When activity detected When releasing force higher than pressing force Interpolation& When activity detected Conservativeness No No Assumption of slowly change VE Update method Irregular update fast interupt Irregular update fast interupt Regular update Algorithm comlexity Simple Simplest Complicated Others Need high-speed RAM (Random access memory)
- 38. Future Works Apply proposed methods to moving and time varying VE. Improve performance of methods: less noise, wider range of impedace, more general cases. Implement to Teleoperation. Implement methods in lower cost devices: MCUs or DSPs.
- 39. References M. C. Cavusoglu and F. Tendick, "Multirate Simulation for High Fidelity Haptic Interaction with Deformable Objects in Virtual Environments," in Proceedings of the IEEE International Conference on Robotics and Automation , 2000, pp. 2458-2465. B. Han, J-H. Ryu “An Injecting Method of Physical Damping to Haptic Interfaces Based on FPGA,” Proceedings of the International Conference on Control, Automation and Systems (ICCAS 2008) , Seoul, Korea, pp. 1835-1840. J-H. Ryu, B. Hannaford, D-S. Kwon, and J-H. Kim, “A Simulation/Experimental Study of the Noisy Behavior of the Time Domain Passivity Controller,” IEEE Trans. on Robotics , Vol. 21, No. 4, pp. 733-741. N. Diolaiti, G. Niemeyer, F. Barbagli, J. Kenneth Salisbury, Jr, ”Stability of Haptic Rendering: Discreatization, Quantization, Time-Delay and Coulomb Effects,” IEEE Transactions on Robotics , 22(2): pp. 256-268, April 2006. J-H. Ryu, B. Hannaford, D-S. Kwon, and J-H. Kim, “A Simulation/Experimental Study of the Noisy Behavior of the Time Domain Passivity Controller,” IEEE Trans. on Robotics , Vol. 21, No. 4, pp. 733-741.
- 40. Implementation on High-Stiffness Moving Objects Master 1 Master 2 Passivate Object Virtual object
- 41. THANK YOU
Editor's Notes
- #5: First of all, we have a review ... What is haptic interfaces and how is it constructed? includes of 3 main parts: PC-based VE, Human operator and Master device. Usually, VE is implemented inside a computer, using GPOS or RTOS (much more expensive) and with slow update rate. Master device is the physical interface with human operator, including the mechanical part and Electrical part
- #37: Before coming to the Conclusions, we have a look at the Max. VE Stiffness graph What is Max. Stiffness? It indicates the Range of Impedance that haptic system can passively render. According to the graph,we can see the multi-rate TDPA has the widest range of Impedance, whille Conv. TDPA has the smallest. Beside, the higher VE frequency the higher stiffness allowed.