A multi-model decentralized controller for teleoperation with time delay

Robust stability constraints can largely limit the performance of bilateral teleoperation systems in the presence of communication time delay. In this paper, a stable decentralized model-based controller is proposed that can enhance the teleoperation transparency in the presence of constant delay. New state/observation transformations produce partially delay-free dynamics/measurement vectors. Using the transformed states/observastions, two local linear quadratic Gaussian (LQG) controllers are implemented at the master and slave stations. The closed-loop stability is analyzed employing the delay-dependent frequency sweeping test. Using the LQG controllers and a simple control switching strategy, a multi- model teleoperation controller is developed that can achieve delay-free position tracking and tool impedance shaping for free motion/soft contact, as well as position and force tracking for contact with rigid environments. Experimental results demonstrate the effectiveness of the proposed approach.