Stable Impedance Reflecting Teleoperation with Online Collision Prediction

In the presence of communication delays, master- slave teleoperation systems suffer from poor contact stability and sluggish performance. In this paper, a new impedance reflecting force-position (F-P) control architecture is proposed in which the master is in interaction with a local model of environment, thus bypassing the delayed contact force received at the master in a typical F-P controller. The local environment model is updated by the environment model parameters that are identified online at the slave and are transmitted to the master. However, due to the delay in model parameter transmission and the slow transition of the identified parameters at contact, the controller experiences contact oscillations in practice. As a remedy, a laser proximity sensor is employed to predict the collision time between the slave and the environment "a delay ahead of time". The incorporation of predicted contact time not only synchronizes the required sudden change in the environment local model dynamics with the remote environment contact event, but also allows for an increase in parameter identification convergence rate. The prediction method is introduced for slave unrestricted motion; however, it is verified on a single degree-of-freedom experimental setup. The performance of the proposed novel impedance reflecting F-P controller with collision prediction is compared to that of a typical F-P controller.