Generalized discussion on design of force-sensor-less Power Assist Control

This paper generalizes the structure of force-sensor-less power assist control (FSPAC) which is a essential technology to design a feedback controller in a human-friendly way. Based on the analysis of the control structure, this paper clarifies the functions of the generalized force-sensor-less power assist control; particularly the functions of two force observers in FSPAC are made clear. Since the FSPAC consists of a positive feedback control, the robustness of the FSPAC is much weaker than the other power assist control with force sensors. This paper clarifies the trade-off between assistance performance and weak robustness in the FSPAC. Comparing power assist control derived from model following design and the disturbance observer based design, the limitation of assistance performance and methods to adjust the gain are revealed. Finally methodology of design the feedback gain in the FSPAC is discussed.

[1]  Yoichi Hori,et al.  Robust speed control of DC servomotors using modern two degrees-of-freedom controller design , 1991 .

[2]  Kouhei Ohnishi,et al.  Human cooperative wheelchair for haptic interaction based on dual compliance control , 2004, IEEE Transactions on Industrial Electronics.

[3]  Toshiyuki Murakami,et al.  Torque sensorless control in multidegree-of-freedom manipulator , 1993, IEEE Trans. Ind. Electron..

[4]  Sehoon Oh,et al.  Sensor Free Power Assisting Control Based on Velocity Control and Disturbance Observer , 2005, Proceedings of the IEEE International Symposium on Industrial Electronics, 2005. ISIE 2005..

[5]  Weng Khuen Ho,et al.  Performance and gain and phase margins of well-known PID tuning formulas , 1995, IEEE Trans. Control. Syst. Technol..

[6]  Il Hong Suh,et al.  Disturbance observer based force control of robot manipulator without force sensor , 1998, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146).

[7]  S. Katsura,et al.  Sensor-less Force Control for Machine Tool Using Reaction Torque Observer , 2006, 2006 IEEE International Conference on Industrial Technology.

[8]  H. Goldstein,et al.  The rise of the body bots [robotic exoskeletons] , 2005, IEEE Spectrum.

[9]  Takamasa Hori,et al.  Robust force control based on compensation for parameter variations of dynamic environment , 1993, IEEE Trans. Ind. Electron..

[10]  A. Sabanovic,et al.  Sliding mode control based disturbance compensation and external force estimation for a piezoelectric actuator , 2004, The 8th IEEE International Workshop on Advanced Motion Control, 2004. AMC '04..

[11]  Craig R. Carignan,et al.  Force Estimation Based Compliance Control of Harmonically Driven Manipulators , 2007, Proceedings 2007 IEEE International Conference on Robotics and Automation.

[12]  K. Hashtrudi-Zaad,et al.  A model-independent force observer for teleoperation systems , 2005, IEEE International Conference Mechatronics and Automation, 2005.