QuadRunner: A Transformable Quasi-Wheel Quadruped

This paper presents QuadRunner, a transformable quasi-wheel legged robot that achieves both quadruped locomotion and wheel locomotion by exploiting a novel semicircular leg-wheel design with a Trotting Wheel gait. We built upon the Stanford Doggo open architecture platform and integrated it with a transformable leg-wheel design to enhance its locomotion capabilities. On its gait control, improvements were made to its trot gait kinematics with end-effector considerations as well as the design of a new trotting wheel gait. Our proposed locomotion strategy found that the robot's legged locomotion improves by an average speed of 10%. In addition, wheel to leg transition takes around 300 ms, and the speed of its wheel locomotion can reach more than five times its body-length/s (2.2 m/s) on flat terrain. Lastly, detailed experiments are conducted to observe the wheel-leg transition performance and gait verification under the absence of foot contact sensors.