Compensating position drift in Time Domain Passivity Approach based teleoperation

Passivity based approaches to bilateral teleoperation control ensure robust stability against disruptive effects of communication delays. These approaches, while achieving velocity tracking, cannot guarantee position tracking in general. Recently, the Time Domain Passivity Approach (TDPA) has been gaining interest in field of bilateral teleoperation due to its simplicity, ease of implementation, robustness to communication delays, and adaptive control design which promises less conservative performance than frequency domain passivity approaches. Several techniques have been proposed to counter the position drift with conventional passivity based approaches, but not much work has been done to address the problem of position drift with TDPA based control of teleoperation. We propose a novel position drift compensation architecture employing a virtual dependent energy source which leverages the passivity margins allowed by the communication channel to inject energy and recover position tracking without compromising system passivity. A drift compensation scheme is developed within this architecture that ensures synchronization of master and slave robot trajectories. The proposed method is generalizable to all bilateral teleoperation control architectures, and is robust against different communication delay and remote environment conditions. Experiments are conducted to validate the efficacy of the approach, and demonstrate position tracking with up to 1000 ms round-trip delays in free space motion and hard wall contact scenarios.