Design and Modeling of a Reconfigurable Robot: Decoupled STAR (DSTAR)

Abstract

This paper presents Decoupled STAR (DSTAR), a novel reconfigurable robot fitted with a sprawling mechanism that allows the wheel rotation axes to vary relative to the body, and two independently activated four-bar extension mechanisms (FBEM). These mechanisms enable the robot to move its center of mass (COM) in any direction, and increase its maneuvering capabilities by selecting a variety of locomotion gaits. A kinematic model of the robot and a quasi-static force analysis are used to optimize the design and evaluate its motor requirements. Experiments demonstrate that combining the sprawling mechanism with FBEM enables the DSTAR to both crawl and drive, overcome a wide range of challenging obstacles, and improve its climbing capability by 66% compared to symmetric FBEM designs (such as RSTAR). The robot can crawl and maneuver over rough terrain using its unique turtle-gait method, roll sideways to surmount wall obstacles up to 20 cm high, travel horizontally across uneven ground, and switch between wheels and whegs to adapt to different terrain types, including dirt, stones, and grass.