Delay-Robust Nonlinear Control of Bounded-Input Telerobotic Systems with Synchronization Enhancement

This letter puts forward a novel controller for joint position tracking of bilateral teleoperation systems subjected simultaneously to time-varying communication delays and bounded actuation. Enhancing such systems' robustness to the larger time delays comes prevalently at the cost of increased settling time for position synchronization. To this end, we propose a general and refined form of nP+D controller that not only mitigates the trade-off between settling time of synchronization and magnitude of time-delay but also exhibits better transient error in position convergence. These advantages are brought along through using capped joint-velocity in the controller, which offers a blessing in disguise in our presented Lyapunov-based stability analysis and allows disposing of the limitation that was originally considered on the nonlinear function's amplitude in previous nP+D controllers. We have shown that by setting conditions on the controller parameters obtained from the analytical study, the closed-loop dynamics' asymptotic stability is ensured. The proposed controller's efficacy and outperformance are validated through numerical simulations and experimental evaluations on a bilateral teleoperation system with multi-DOF robots as the leader and follower.