Velocity/Force Capacities of a Six-Legged Walking Machine

Six-legged robots are reliable locomotive machines with actuation redundancy. This paper analyzes the force and velocity capacities of a six-legged high-payload robot geometrically and numerically. The full-body Jacobian between the body platform and the actuation is first of all computed. A geometric computation approach is then proposed to obtain the robot velocity/force polytopes in the platform operational space. System physical constraints of joint torques and velocities are taken into account so that the task space capacities could be quantitatively given. Besides, several capacity indices are also investigated, including the maximum velocity/force magnitude, the maximum velocity/force along a given direction and the maximum isotropic velocity/force. At last, the robot capacities are numerically analyzed with different supporting legs. The results verify high payload capacity of the robot and clarify the influence of different gait parameters on the task space performance. Our method is proposed in a general and convenient framework, and therefore it is beneficial for the quantitative performance evaluation of any multi-legged walking machine with actuation redundancy.