Deformable soft wheel robot using hybrid actuation

The mobility of a wheeled robot in various terrains is basically limited by the size of the wheel. If the size of the wheel is fixed, the robot can only pass through a hole bigger than the wheel size. Furthermore, the robot cannot climb stairs much higher than the wheel size. Therefore, for a wheeled robot that has fixed dimensions, it is hard to improve the mobility depending on unexpected situations such as passing through a hole smaller than the original robot size and climbing stairs much higher than the original wheel size. To deal with the scale problem, we propose a deformable wheeled robot that can change the shape of the wheel depending on the obstacles. It improves the mobility the wheeled robot. In order to make the simple and robust robot, we employ smart structures and actuators such as composite flexure linkages, deformable polymers and shape memory alloy actuators. The robot shows three kinds of motion with combination of the motor and the SMA coil actuator. The motor is used for driving the wheel and the SMA coil actuators deform the wheel to produce a caterpillar-like motion. Using both actuators, the legged wheel motion can be produced. The light weight and the multimodal locomotion of the robot enhance the mobility for the search and rescue robot application.