Two robot arms in assembly

When two robot arms execute coordinated motions in assembly, collision between the two end-effectors cannot be avoided. The collision effects on the robot motions are studied in this paper. Firstly, the joint velocities of the two coordinating arms have abrubt changes at the instant of collision. Secondly, an impulsive force exerted on the end-effector is generated. The magnitude and the direction of the impulsive force depend on the relative position and orientation between two collideing end-effectors. Therefore the impulsive force can be used to detect the position and orientation errors between two coordinating arms. A wrist force sensor is suggested to be installed at the wrist of each robot arm. The information produced by the wrist force sensors can then be used to adjust the relative position and orientation of the two robot arms in assembly.