Quattroped: A Leg--Wheel Transformable Robot

This paper reports on the design, integration, and performance evaluation of a novel four-leg/four-wheel transformable mobile robot, Quattroped. In contrast to most hybrid platforms that have separate mechanisms and actuators for wheels and legs, this robot is implemented with a unique transformation mechanism that directly switches the morphology of the driving mechanism between the wheels (i.e., a full circle) and 2 degrees of freedom leg (i.e., combining two half circles as a leg), so that the same system of actuation power can be efficiently utilized in both wheeled and legged modes. The design process, mechatronics, software infrastructure, behavioral development, and leg-wheel dynamic characteristics are described. The performance of the robot is evaluated in various scenarios, including driving and turning in wheeled mode, driving, step and bar crossing, irregular terrain passing, and stair climbing in legged mode. Taking advantage of the leg-wheel combination on a single platform, the comparison of the wheeled and legged locomotion is also discussed.