Control Method of a Load-Carrying Quadruped Walking Vehicle with Trotting GaitBased on the Centroidal Dynamics and the Virtual Model

A control method combining the centroidal dynamics and the virtual model is proposed, in order to improve the walking stability of a load-carrying quadruped walking vehicle with trotting gait and to reduce the influence of large leg mass and eccentric mass on stable walking. The accelerations of the vehicle body and the swing-legs are solved by using the virtual model control method. Combined with the centroidal dynamics model, the external forces on the vehicle are obtained. Then, the quadratic programming is applied to distributing the resultant external forces to the supporting legs. The joint moments of the walking vehicle are obtained by using the inverse dynamics and the PD (proportional-differential) control in the joint space. Adams and Simulink are used to simulate the trotting gait of the load-carrying quadruped walking vehicle, and comparisons are made between the proposed algorithm and the virtual model control algorithm. Results show that the centroidal dynamics and virtual model control method can stabilize the attitudes of the vehicle around the target values. And the roll and pitch angles of the vehicle are reduced by 42% and 21.8% respectively under a lateral impact, and reduced by 50% and 89% respectively during omni-directional walking with a vehicle eccentric weight. Therefore, the proposed control method can effectively deal with the influence of large leg mass and eccentric mass, and improve the walking stability and robustness of the load-carrying quadruped walking vehicle with trotting gait.