A Rigid-Flexible Coupling Oscillator for Pneumatic Autonomous Robots

The traditional oscillators are limited by their material characteristics and structural configuration, exhibiting a low oscillation frequency and low output power under pressure input. This results in a slow locomotion speed for the robot. To address these limitations, this work presents a compact, lightweight, and rigid-flexible coupling pneumatic oscillator that is driven by a single, constant input pressure. The oscillator exhibits a specific power of 70 W/kg and is capable of achieving a motion with a high linear reciprocating frequency (94 Hz) based on the hysteresis characteristic of the soft membrane. The hysteresis characteristic was modelled, and the validity of the model was verified through experimentation. The integration of the oscillator enabled the creation of a transmission-free and electronics-free flapping micro-air-vehicle capable of travelling at speeds up to 0.94 m/s. Furthermore, an amphibious robot driven by the two oscillators is able to achieve both straight motion and turning motion in both aquatic and terrestrial environments. The proposed oscillator provides a new solution for robots to move quickly without the need for complicated control systems and electronic elements, marking a significant step towards the automation of pneumatic robots.