Singular perturbation control for flexible-joint manipulator

The traditional singular perturbation approach can only be used in the robot system with weak joint flexibility. In order to solve this problem, a joint flexibility compensator was designed, which can increase the equivalent joint stiffness. So the limitation for the singular perturbation approach was removed and it can be extended to the robot system with normal joint flexibility. Besides these, an adaptive control law was designed for the slow subsystem, which can guarantee the trajectory error asymptotical tracking. The proposed control strategy can be applied to the engineering systems conveniently without any joint flexibility limitation and does not need the link acceleration or jerk information. Finally, an experimental study on the flexible joint manipulator was executed and the results verify that whatever the PD, computed torque or adaptive control are used in the slow subsystem, the proposed singular perturbation strategy is more valid than the traditional one.