Design of Quadruped Robot for Overcoming High Step

(Executed with Leg-Mecanum hybrid configuration)

Abstract

Quadruped robots are expected to use on a terrain with high undulation, especially a high step. This paper describes a design concept and practical method to decide a leg parameter to overcome relatively higher steps to the robot size. The situations of front and rear leg are different in the case of stepping from lower ground to the higher step, avoiding a collision of leg and the step. Front shin should be almost vertical when it is on the lower ground, but can be up to almost horizontal to reach its foot to the step. Contrary, rear shin should be kept vertical during a swing from lower ground to the higher step. Thus, the required vertical movable range of thigh is different. The front thigh can be designed with additional shin length, but rear thigh should have its own movable range of overcoming step height. Introducing a new concept of cross leg configuration, where front leg roots the rear end of body and rear leg roots the front end of body, the whole robot can be designed small relative to the length of leg linkage. Equipping mecanum wheels on each foot, the machine can move omnidirectionally without sideways motion of leg linkage, and become stiffer and lighter. All these concepts are verified by a manufactured robot with the size of overcoming 700mm steps.