Towards stable and efficient legged race-walking of an ePaddle-based robot

ePaddle mechanism is a novel hybrid locomotive mechanism designed for accessing terrestrial, aquatic and amphibious terrains with versatile locomotion gaits. Among those gaits, race-walking gait has a promised gait that is potential for achieving highly stable, and highly energetic efficient legged walking. This paper studies the motion planning method of this unique race-walking gait for an ePaddle-based quadruped robot. The standard gait sequence that consists of four phases is firstly presented. The selection of wheel-center trajectory for achieving the gait is then discussed based on kinematic models of the ePaddle module in these phases. Two motion planning methods are presented for an ePaddle-based quadruped robot to track planar path with the proposed race-walking gait. Stability and energetic performances of the proposed race-walking gait are discussed by evaluating duty factor of the ePaddle module, and by measuring stability margin and specific resistance of the robot. A set of simulations on tracking straight and circular paths verifies the idea of the race-walking gait as well as its stability and efficiency.