Gait Optimization Method for a Large Heavy Load Biped Robot Based on Particle Swarm Optimizer Algorithm

Abstract

In this paper, we present the innovative design of a highly robust bipedal robot featuring parallel legs and delve into its intricate gait planning strategy. This novel leg mechanism, meticulously crafted to achieve six degrees of freedom through the parallel integration of six precise linear motion mechanisms, exemplifies exceptional load-bearing capacities and unparalleled stability. Leveraging the robot’s intricate structure and geometric parameters, we have developed a comprehensive kinematic model for a single leg, revealing the intricate mapping between joint movements and end-effector dynamics. By precisely controlling these joint movements through servo motors, we are able to orchestrate the robot’s locomotion with remarkable precision. To guarantee seamless and smooth motion of the swing leg during the robot’s cyclical walking pattern, we have initially adopted a quintic polynomial for gait planning. This strategic approach ensures that both velocity and acceleration smoothly transition to zero at the onset and cessation of the robot’s movement, thereby eliminating impact during raising and landing phases. Recognizing the significance of high loads and the intricate interplay of component centers of gravity on dynamic stability, we have further refined our design by utilizing a Particle Swarm Optimization (PSO) algorithm to optimize the motion of the upper platform. This optimization is grounded in the principles of the Zero Moment Point (ZMP), with the ultimate aim of maximizing the stability margin. Experimental validation has robustly confirmed the viability of our robot’s design and the soundness of our basic gait planning strategy. Furthermore, simulation studies have demonstrated that the optimized gait, which meticulously accounts for the influence of self-weight and varying loads, empowers the robot to operate seamlessly at the uppermost boundaries of stability. This optimized gait showcases continuous joint and spatial motions, marking a significant enhancement in the robot’s overall motion performance and capabilities.

Keywords

• Biped robot
• dynamic stability
• ZMP
• PSO