Experiments in Local Force Feedback for High-Inertia, High-Friction Telerobotic Systems

Abstract

Many telerobotic systems include a slave robot with much larger inertial and frictional properties than the master robot and/or a non-backdrivable slave acting as an admittance device. Passive controllers, which are known for their stability and robustness, display the large dynamic forces to the user and/or become insensitive to contact forces. In effect, the user feels the large inertia and friction of the slave robot but does not feel the force of the environment. Force sensors can isolate the environment forces. In this paper, we experiment with local force feedback for an admittance type slave robot. We use the local controller to convert the slave to an apparent impedance device, restoring its sensitivity to environment forces. This will allow the application of stable passive teleoperation controllers. The control structure is validated on a single axis of a large, non-backdrivable, industrial Adept robot operating as a slave in contact and in free space.