Bilateral Teleoperation under Communication Time Delay Using an LQG Controller

The communication channel delay can adversely affect performance and stability of bilateral teleoperation systems. This paper proposes a discrete-time Linear Quadratic Gaussian (LQG) controller that delivers a transparent stable response in the presence of constant communication latency. Different controllers are designed for each phase of operation, i.e. free motion and contact with rigid environments. Switching between the controllers occurs according to the identified contact phase. The treatment of the problem in the discrete-time domain allows for the development of a finite dimension state-space model that explicitly includes the time delay. Performance objectives such as position tracking and tool impedance shaping for free motion, as well as position and force tracking for contact with rigid environments are incorporated into the LQG control design framework. Experimental studies demonstrate that the proposed control technique is highly effective in providing a stable transparent interface for teleoperation under time delay.