Wheel Locomotion of a Biped Robot Using Passive Rollers

This paper proposes the leg-wheel locomotion of a biped robot. The feet of the robot consist of wheels that move forward with the periodic motion of a leg under a double-leg support. There are many types of approach leg-wheel hybrid systems; however, biped system with passive wheels is rarely used. A special axle mechanism is introduced so that the wheels could smoothly track a curved path for propulsive motion. Finally, the robot achieves not only straight and circular motion but also pivoting motion that is significantly faster than walking, while implementing a minimal number of simple components. The concept of locomotion, function of the mechanism, and experimental results are described in this paper.