Abstract: Aiming at the problem of less research on wheellegged quadruped robot with variable body width and with waist joint, a new type of wheel legged quadruped robot was proposed, and the structural parameters of its leg mechanism were optimized. The whole machine model and leg structure model of quadruped robot were established by Solidworks. The kinematics analysis of the robot leg mechanism was carried out, and the forward and inverse solution formula of the leg mechanism was derived, and the forward and inverse solution formula of the position was verified by MATLAB. Monte Carlo method was used to solve the foot end workspace, the influence law of leg structure size parameters on the foot end workspace was analyzed, and the main parameters affecting the workspace were summarized. Taking the workspace as the optimization index, genetic algorithm was used to optimize the main structure size parameters. The results show that the positive and negative kinematics formulas derived are correct. The working space shape of the leg mechanism meets the walking requirements of the robot. The main structural parameters affecting the space of leg mechanism are r0、r2、r4、l1. The volume of the working space increased by 68% after the optimization of the structural parameters.

Key words:  wheel legged quadruped robot; leg mechanism; parameter optimization; genetic algorithm; workspace