FPAA-based control of bilateral teleoperation systems

Discretizing the continuous-time controller of a master-slave teleoperation system can simplify control implementation. However, in teleoperation systems, discrete-time control can cause a performance degradation compared to continuous-time control. In digitally controlled bilateral teleoperation systems, there exist stability-imposed bounds on the gains of the discrete-time controller and the sampling period, and a trade-off between the two. This means that given a sampling period, it is impossible for the discretized controller to have gains above a threshold, which may well be necessary for successful performance of teleoperated tasks requiring highly accurate master-slave position tracking. In a teleoperation system with analog controller, however, stability does not impose any upper bound on the control gains, thus facilitating the performance of tasks that do require highly accurate master-slave position tracking. Inspired by this advantage of analog control, in this paper we develop a Field Programmable Analog Arrays (FPAA) based controller for bilateral teleoperation, which can achieve higher control gain than its discrete-time counterpart. We present the results of a user study measuring the human performance for a task involving flipping a stiff switch through a teleoperation system. We experimentally show that large sampling periods, necessitating low control gains for maintaining stability, lead to unacceptable task performance. We then show that humans can successfully perform the same task with the FPAA-based controller for the teleoperation system.