Design of A Novel Wheel-legged Robot with Rim Shape Changeable Wheels

Abstract

Abstract The wheel-legged hybrid structure has been utilized by ground mobile platforms in recent years to achieve good mobility on both flat surface and rough terrain. However, most of the wheel-legged robots only have one-directional obstacle-crossing ability. And during the motion, most of the wheel-legged robots’ centroid fluctuates violently, which damages the stability of the load. What’s more, many designs of the obstacle-crossing part and transformation driving part of this structure is highly coupled, which limits its optimal performance in both aspects. This paper presents a novel wheel-legged robot with rim shape changeable wheel, which has the bi-directional and smooth obstacle-crossing ability. Based on the kinematic model, the geometric parameters of the wheel structure and the design variables of the driving four-bar mechanism are optimized separately. The kinetostatics model of the mobile platform when climbing stairs is established to determine the body length and angular velocity of the driving wheels. A prototype is made according to the optimal parameters. Experiments show that the prototype installed with the novel transformable wheels can overcome steps with the height of 1.52 times of its wheel radius with less fluctuation of its centroid and performs good locomotion capabilities in different environments.