Real time collision free motion control in telerobotic systems

摘要

On-line collision free motion control is one of the most important functions in telerobotic systems. Autonomous collision free motion controller can dramatically reduce the human operator's workload especially in the presence of complex environment with unknown obstacles. In this paper, a novel simple approach is presented to provide on-line collision avoidance (CA) function to the telerobot controller by adding a collision detection module and a joint velocity adjustment module to the commonly used RMRC (resolved motion rate control) control scheme. When the robot arm encounters obstacles while tracking the commanded motion, a virtual repulsive force is generated based on the nearest distance and the relative approaching velocities between the robot arm and obstacles. This Cartesian space virtual force then is used to repel the robot arm away from obstacles by adjusting the joint velocities. The relation between the joint velocity adjustment and the Cartesian space collision is studied. As a joint velocity based strategy, the approach can be implemented easily based on any on controller with joint velocity servo loop. The algorithm is computationally efficient to be adopted in real time. Simulation studies show that the approach can produce smooth stable CA actions while tracking the predefined trajectory.