Balance Control of Quadruped Robot under External Disturbance using Quadratic Programming and Impedance Control

Abstract

Legged robots are widely used in complex environments because of their strong motion flexibility and environmental adaptability. However, uncertain external disturbances in complex environments will bring adverse effects on the stability and motion state of robots in the actual working process. For quadruped robot operating under external disturbance in complex environment, a dynamic balance control framework based on QP (quadratic programming) method and impedance control is proposed in this paper. The whole robot control system adopts dynamic control scheme. We use the single rigid body model to simplify the dynamics model of the quadruped robot, and use QP with friction cone constraint to optimize the desired foot contact forces, and achieve the optimal distribution of foot contact force. Impedance control is used to smoothly control the swing leg of a quadruped robot, which greatly reduces the impact of the swing leg and the ground on the robot body. In this paper, the A1 quadruped robot of Unitree Technology was simulated by Webots. The experiments showed that A1 quadruped robot could resist 60N lateral impact force and continuous external drag force, which verified the effectiveness and robustness of the proposed control algorithm.