Fixed-time disturbance observer-based non-singular sliding mode tracking control for quadruped robots

• 1、School of Automation, Guangdong University of Technology, Guangzhou 510006
• 2、Guangdong-Hong Kong Joint Laboratory for Intelligent Decision and Collaborate Control,Guangzhou 510006
• 3、Guangdong Province Key Laboratory of Intelligent Decision and Cooperative Control,Guangzhou 510006

Abstract：Quadruped robots have shown significant potential in challenging and complex applications, such as fire rescue and military reconnaissance. However, during quadrupedal locomotion, various uncertainties, such as unmodeled coupling effects, varying payloads, and parameter mismatches, can substantially degrade system performance. To address the locomotion control problem of quadruped robots under unknown disturbance, this paper presents a fixed-time disturbance observer-based non-singular sliding mode tracking control strategy. A single rigid-body model is initially used to describe the dynamics of the quadruped robot, followed by the design of fixed-time disturbance observers to quickly estimate unknown disturbance in both translation and rotation directions. Considering the friction cone constraints on the foot-end forces for quadruped robots, the optimal foot-end forces are determined using a quadratic programming approach. The effectiveness of the proposed strategy is validated through simulations and real-world experiments on the Unitree quadruped robot GO1. Experimental results demonstrate that, compared with the {${L_1}$} adaptive control and baseline control strategies, the proposed control strategy effectively compensates for unknown disturbance and significantly enhances the accuracy of the robot's position and attitude trajectory tracking.

Keywords： quadruped robot fixed-time disturbance observer non-singular sliding mode control Disturbance trajectory tracking