Bilateral Control and Stabilization of Asymmetric Teleoperators With Bounded Time-Varying Delays

A novel control scheme for asymmetric bilateral teleoperation systems is developed based on linear models of the hardware, with considerations in the existence of communication time delays. The master and slave manipulators were modeled as linear single degree of freedom systems. The human user force was modeled based on the band limited availability of human motion, and the environmental force was modeled as a spring and damper combination based on the slave position. The configuration of the whole system represents a relatively general framework for the teleoperation systems. The main contribution of the work can be concluded as follows. First to deal with asymmetric systems in teleoperation, an impedance matching approach was applied to the master side dynamics, while a static error feedback gain was used to stabilize the slave side dynamics. Second, in the existence of bounded random time-varying delays, approaches and techniques based on the Lyapunov method proposed for network controlled systems are now proposed for bilateral teleoperation systems. Specifically, a Lyapunov functional is proposed with consideration for the upper and lower bound of random delays. Linear matrix inequality (LMI) techniques are used with rigorous stability proof to design the slave side controller control gains. Furthermore, the cone complementarity algorithm is used to deal with nonlinear terms within the LMI under the new formulation. Finally, the applications of the proposed algorithm to haptic devices are described thoroughly, and experimental results with comparisons to simulation results are demonstrated to show the effectiveness of the proposed approach.