Real-time collision avoidance of robot manipulators for unstructured environments

A real-time collision avoidance approach for complete posture (all links) of a robot manipulator in an unstructured environment based on a modified impedance control concept is presented. Instead of high-level trajectory planning and an offline collision avoidance approach as used in conventional methods, robot trajectories are generated in operational space. Multiple moving obstacles are avoided in real-time as part of the lower level control task. The concept is very suitable for real-time applications since the defined impedances are linear and can be obtained directly using robot kinematics variables without an inverse kinematics function. Moreover, the impedance between the obstacle and any point on the robot arm utilizes the linearity property of the Jacobian function and can be calculated by using a simple geometric relation. The problem of local singular configurations is eliminated by this technique