Wave variable controllers maintain passive communication across time delays in telerobotics. As passive elements, wave variable controllers interact well with other passive elements, such as P.D. controllers and masses, and use a combination of force and velocity signals to apply force feedback. Currently we are exploring the use of wave variable controllers with large non-backdrivable industrial-type slave devices where dynamics are dominated by inertial and frictional forces. The objective is to integrate force sensor measurements into wave variable controllers to provide low frequency force feedback and hide the slave’s friction and inertia from the user in the presence of a communication time delay. This paper presents and uses a wave variable based approach to design force control. The resulting wave variable based force controller is converted to power variables and shown to be similar to traditional force controllers. A 1-DOF telerobotic system is used to experimentally show the wave variable based force control combines with the enhanced stability properties of the wave communication channel to produce robust slave side force control. The resulting system is better able to maintain force control with rigid environments then a traditional controller both with and without communication time delay.
Contact Task by Force Feedback Teleoperation Under Communication Time Delay
