Development of HYDROVER: A Torque-Controlled Hydraulic Rover

This paper presents the development of a four-legged, four-wheel-drive hydraulic-powered rover that can traverse irregular terrains such as agricultural or forest landscapes while carrying manipulators, etc., to do heavy-duty work. The rover is equipped with driving wheels at the tip of its legs and passive wheels at its knees or the bottom of its belly. By controlling the joints’ torque directly using hydraulic actuators, the contact forces at its rolling contact points can be optimally distributed according to the rover’s states. This allows the acceleration of the rover’s center of gravity and posture to be controlled while accommodating the terrain. This paper describes the mechanical design and control system of the rover, as well as the preliminary experiments. Although the torque control for the driving wheels is not yet successfully implemented, the experimental results using two rover prototypes imply the promising technological capacity of torque-controlled rovers with low-cost hydraulic components.