Robust control of flexible joint manipulator based on singular perturbation

Aiming at the problem that in the flexible joint manipulator it is difficult to achieve high-precision trajectory tracking under the condition of large disturbance, a robust control scheme based on singular perturbation was proposed. This method does not need to calculate the angular acceleration of the connecting rod and its higher-order derivative, so it is not affected by the inaccurate estimation of the higher-order derivative. First, the singular perturbation method was used to decouple the original system, and two second-order subsystems with different time scales were obtained. Then, a multiple compensation control law was designed for the slow subsystem. After the disturbance was observed by the disturbance observer, the first compensation was performed; A robust controller based on Hamilton-Jacobi-Issacs inequality theory was designed for secondary compensation. And it is proved that when the disturbance is bounded, the system tracking error will quickly converge to zero. Finally, the damping term was added to the fast subsystem, and the stability of the system was proved by Lyapunov stability theorem and Lasalle invariance theorem. Comparing the proposed control scheme with the feedback linearization scheme and the singular perturbation PD control scheme, the results show that the system designed by the proposed control scheme has strong anti-interference ability and better dynamic and steady-state performance. © 2024 Editorial Department of Electric Machines and Control. All rights reserved.