A Simple Tripod Mobile Robot Using Soft Membrane Vibration Actuators

Recent research on mobile robots has focused on increasing their adaptability to unpredictable and unstructured environments using soft materials and structures, and pneumatic actuators have been widely used in soft mobile robots. In spite of their advantages, existing pneumatic actuators have limitations with regard to control and speed. We propose soft membrane vibration actuators for a simple tripod robot. The proposed actuators are composed of a rigid housing and a soft membrane that creates vibration based on the input air pressure. The mobile robot proposed here has three vibration actuators arranged in an equilateral triangle configuration. Based on the pressure on each actuator, the robot can easily realize both translational and rotational motions. We constructed an analytical model of the proposed actuator and characterized the behavior of the robot experimentally. We also implemented model-free control based on a Gaussian process. The robot demonstrated the ability to follow the trajectories of various polygons. It could also carry a payload five times heavier than its own weight.