Operational Space Control Under Actuator Bandwidth Limitation

The actuator bandwidth limitation deteriorates the stability and performance of torque-based robot controllers. Operational space control is especially prone to this problem, since the limited bandwidth of a single actuator can reduce the performance of all related tasks simultaneously. In this article, an intuitive way to penalize low performance actuators is proposed to improve the performance of the operational space controller. The basic concept is to add joint torques only to high performance actuators, when the control bandwidth cannot reach the target level using all actuators. If that is not enough, additional torques are commanded to even higher performance actuators. This procedure can be executed recursively, meaning the controller can achieve almost maximum performance under the actuator bandwidth limitation. The proposed method was experimentally verified using the robot manipulator Franka Emika Panda.