Adaptive fixed-time control based on super-twisting disturbance observer for manipulators

For the high control performance of the manipulator system, a fixed-time control algorithm based on a super-twisting disturbance observer (STDO) is designed in this paper. Firstly, an STDO is proposed to process the disturbance and then compensate the system with feedforward for the issue that the lumped disturbance is difficult to determine. On this basis, the fixed-time sliding mode (SM) surface and adaptive reaching law are designed. The reaching law gains are changed by the adaptive law to enhance the robustness and anti-interference of the system. Meanwhile, the Lyapunov theory is used to examine the stability of the closed-loop system, and it is shown that the system state can converge to a specific area during the sliding and reaching phases. Finally, the superiority and effectiveness of the control strategy raised in this work are verified by simulation.