Configuration-Based Wheel Control for Step-Climbing Vehicle

Abstract

We propose a derivation of adaptable wheel rotation velocity for negotiating irregular terrain based on vehicle configuration. We developed a holonomic vehicle capable of negotiating steps and running around omnidirectionally on a flat floor using seven special wheels and two passive links. Each wheel has its actuator, requiring that the rotation velocity of individual wheels be coordinated, which is difficult due to changes rotation speed when the passive link negotiates the irregular terrain. Unstable rotation velocity calculated without considering the vehicle configuration causes wheel slippage and rotation error that adversely affect mobility on rough terrain. Because conventional general traction control cannot coordinate wheel velocity, we propose reference derivation that does so based on the vehicle configuration. In the sections that follow, we focus on (1) the derivation of individual wheel velocity during step climbing and (2) adaptation to wheel control reference while balancing rotation velocity among wheels. We confirm the feasibility of our proposal in experiments using our vehicle prototype.