Improved Force Control for Conventional Arms Using Wrist-Based Torque Feedback

Torque control is an effective technique for improving robot performance. However, most conventional robots are not equipped with torque sensors, and they are difficult to add without modifying the robot's mechanical structure. To address this problem, we have developed a new method that allows torque feedback to be implemented in the absence of joint-torque sensors. This technique estimates the torque components acting in the force-control subspace, using a conventional wrist force sensor. We have implemented and experimentally validated this approach using a PUMA 560 manipulator. Our results confirm the effectiveness of this method in dealing with the limitations of conventional actuation/transmission systems.