Modular Two-Degree-of-Freedom Transformable Wheels Capable of Overcoming Obstacle

This study presents modular transformable wheels capable of overcoming obstacles. They can be used for indoor service robots or service platforms such as wheelchairs and baby carriages, which often move up and down on thresholds or on sidewalks. The structure of the wheel and transformation mechanism are introduced. The wheel has two built-in brushless DC (BLDC) motors. The BLDC motor is remodeled to add the gear box inside. These motors create a two-degree-of-freedom (2-DOF) transformation of the wheel. The 2-DOF mechanism is achieved by a 7-bar linkage with six rotational joints and one prismatic joint. A platform using the presented modular transformable wheels was used to experimentally verify the ability to climb up and down a staircase.