Design of sliding mode control for underwater robot based on fixed-time disturbance observer

Abstract

The estimated time in the motion control of underwater robots is highly susceptible to initial disturbance values when estimating model parameter errors and external unknown dynamic disturbances. Firstly, utilizing the characteristics of a fixed-time observer, we estimate the parameter errors and external disturbances of the underwater robot and compensate for disturbance estimation. Secondly, considering the characteristics of sliding mode control accompanied by buffeting, we design an approach law with improved adaptive parameters to suppress buffeting. Finally, simulation results validate that the adaptive synovial control design based on a fixed-time disturbance observer accurately obtains disturbance estimates within a fixed time frame, effectively mitigates system buffering, and enhances steady-state precision in underwater robot motion control.