Real-time collision avoidance for redundant manipulators

The paper presents a joints trajectories planning strategy for a redundant manipulator. The control system modifies, in real-time, the robot manipulator joints references positions, during a transition, when an unexpected moving obstacle is getting closer to one of the robot components (links and joints). The position of the moving objects is determined using a digital image processing system. The control system determines if the moving obstacle and the arm robot are in collision using an interference detection method based on oriented bounding boxes. When the arm robot control system detects a collision, it modifies the arm robot joints trajectories in order to increase the distance between the robot and the obstacle and, in the same time, maintain the initial trajectory of the end-effecter. Computer simulation and experimental results are given for a 7 DOF redundant arm and demonstrate the collision avoidance capability.