Robust stability in γ-4C based teleoperation

This paper investigates the possibility of deriving frequency-domain conditions for robust stability in presence of time-varying communication delays and parametric uncertainties in the four-channel control scheme. This teleoperation setup can be modeled as a negative single feedback loop containing a linear time invariant LTI block and an uncertain time-varying delay for applying the analysis tool based on mu-plots. With this model we can also justify the proposed γ-4C scheme, which introduces a tuning factor γ to increase in practical conditions the stable region fixing the desired bounds on time-varying delay, with the particularity of maintaining the tracking properties provided by the 4C transparent control scheme. Simulation results justify the proposed controllers and confirm the stability robustness.