Enhancement of Path Tracking Accuracy for Physically Coupled Industrial Robots by Hybrid Position-Torque Compensation

In robot-driven manufacturing, physically coupled industrial robots exhibit a higher stiffness to resist process forces than a single robot. However, the internal stress between the coupled robots leads to deformation in the joints, which results in the deviation of the tool from the manufacturing path. As the state-of-the-art accuracy enhancement techniques are not extended to physically coupled industrial robots, this paper proposes a hybrid position-torque compensation method that improves the path tracking accuracy. The method is based on the dynamics of coupled robots where the error propagation towards tool deviation is handled explicitly. In the implementation, the compensation is solved by the quadratic programming and a reduction of tool deviation by 61.6% is achieved w.r.t. the case without compensation.