Position-error-based force-reflecting teleoperation

The feedback of contact force to human operator can greatly enhance the performance of a teleoperation system. Most previous research on force-reflecting teleoperation assumes the use of force/torque sensors, which are expensive and noise prone. This thesis is an attempt to achieve stable and transparent force-reflecting teleoperation by using position only, instead of force/torque measurements.; A preliminary study on performance shows that the traditional position-position architecture with fixed-gain controllers provides poor transparency, especially when the slave is either in free motion or in hard contact. Gain-switching is desired to improve the transparency. When the slave manipulator is establishing contact with a stiff environment, severe chattering instability may result from inappropriate controller design. Contact stability is studied in this work. A rigorous proof of contact stability is shown for a teleoperation system with constant controller gains. Based on this, a switching strategy is proposed to guarantee the contact stability for a gain-switching teleoperation system. A gain-switching control scheme with on-line detection of contact versus free motion is then developed. The advantages of this method are multi-fold and validated experimentally.; The interaction of a teleoperation system with environments having different impedances between free motion and hard contact is also investigated. The position-force architecture with force/torque estimation is attempted to improve performance. Theoretical and experimental results show that it is superior to the position-position architecture in performance, while stability is sacrificed. A new application of bilateral teleoperation, human-to-human interaction with force feedback, is also discussed in this thesis. Fuzzy logic; tuning is employed to achieve telepresence without using force/torque sensors.