Robust stability of teleoperation schemes subject to constant and time-varying communication delays

This paper addresses the robust stability of some bilateral teleoperation control scheme subject to various constant and/or time-varying delays in the communication channel. The stability conditions are derived using frequency-domain techniques. More specifically, in the case of constant delays, the stability regions of the systems´ parameters are completely characterized. Next, the analysis is extended to the case of time-varying uncertain delay, and we derive sufficient (closed-loop) stability conditions.