Implementation of H2 optimal controller for a single link flexible-joint robot

The controller design and implementation of a single-link flexible-joint robot is presented. To improve the performance of current industrial robots, the controller is designed using actuator-based sensory feedback information only, a departure from current research approaches that utilize joint feedback information. The H₂ optimal controller based on a quadratic performance index in the frequency domain is derived. Feedforward compensation schemes that compensate the gravity effect and improve the tracking accuracy are proposed. An experimental system consisting of a single-link robot is established for verifying the control strategy. Experiments show the good performance of the H₂ controller in stiffening the flexible joint and in tracking desired polynomial-type trajectories