A Hybrid Tracked-Wheeled Multi-Directional Mobile Robot

Abstract This paper presents the novel design and integration of a mobile robot with multi-directional mobility capabilities enabled via a hybrid combination of tracks and wheels. Tracked and wheeled locomotion modes are independent from one another, and are cascaded along two orthogonal axes to provide multi-directional mobility. An actuated mechanism toggles between these two modes for optimal mobility under different surface-traction conditions, and further adds an additional translational axis of mobility. That is, the robot can move in the longitudinal direction via the tracks on rugged terrain for high traction, in the lateral direction via the wheels on smooth terrain for high-speed locomotion, and along the vertical axis via the translational joint. Additionally, the robot is capable of yaw axis mobility using differential drives in both tracked and wheeled modes of operation. The paper presents design and analysis of the proposed robot along with a dynamic stabilization algorithm to prevent the robot from tipping over while carrying an external payload on inclined surfaces. Experimental results using an integrated prototype demonstrate multi-directional capabilities of the mobile platform and the dynamic stability algorithm to stabilize the robot while carrying various external payloads on inclined surfaces measuring up to 2.5 kg and 10 deg, respectively.