Hybrid virtual-proxy based control framework for passive bilateral teleoperation over the internet

Abstract

Let us consider the control problem of bilateral teleoperation over the Internet. One of its important, yet, often overlooked, aspects is its hybrid nature, that is, the (nonlinear) master and slave robots are continuous-time systems with sampled-data controls, while the Internet between them is a discrete-time packet-switching communication channel with the communication unreliability (e.g., varying-delay, packet-loss, data duplication/swapping, etc.). To tackle this problem, a hybrid proportional-derivative (PD) type control framework has recently been proposed in [1], which, by utilizing the hybrid nature, can enforce closed-loop passivity and asymptotic position/force coordination, by compensating for the Internet's communication unreliability solely via device viscous damping. This scheme of [1], yet, requires large device damping when the communication delay/loss is large, thus, would not be so suitable if the device's un-tunable damping is low, but, the communication unreliability is severe. In this paper, extending the results of [1], [2], [3], we propose a novel virtual-proxy based hybrid teleoperation control framework, which can passify the Internet's communication unreliability through the virtual proxy's tunable discrete damping, thus, removing the requirement of large device damping of [1] and rendering a more flexible framework than [1], while providing explicit position feedback via the PD-action. Simulation is also performed to verify the theory.