Control and Omni-directional Locomotion of a Crawling Quadruped

robot to mass (with friction) Force in, velocity out causality Ewoud Vos 6 Mass Impedance Legged robot controller Fig. 1: Abstraction of a legged robot to an omni-directional moving mass that can then, for instance, be controlled by an impedance controller. Fig. 1. This scheme requires a gait controller that ensures that the legs move to support the motion of the robot. The gait generator as proposed by Estremera and de Santos [2] is capable of generating a gait based on the omni-directional velocity of the robot body and is, for this reason, particularly suitable to be used in the proposed control scheme. In addition, we present theory to determine the theoretically maximum achievable velocity of a quadruped and compare the speed performance of the selected gait generator with this optimum to validate its performance. This paper is structured as follows: in Sec. 2, the use case for supporting the theory and evaluating the performance of the gait generator is described. In Sec. 3, the proposed controller structure is presented and explained, including a summary of the gait generator. In Sec. 4, we present theory on the maximum velocity of a quadruped and treat how this applies to the use case. In Sec. 5, the speed performance of the simulated gait generator is presented. In Sec. 6, the simulation results are compared with the theoretical optima and in Sec. 7, conclusions are drawn.