Fig. 2: Concept and working principle of the pneumatic hybrid oscillator (PHO).
From: A non-electrical pneumatic hybrid oscillator for high-frequency multimodal robotic locomotion
a Design principle of PHO. b Demonstration of the oscillation process of PHO. c The relation between the stored potential energy of the elastic beam and the active joint. d The nonlinear relationship between the rotation angle of the active joint and the passive joint, where \({\theta }_{c}\) and \({\theta }_{p}\) are the critical angle of the active joint and passive joint, respectively. e During the oscillation, the active joint rotates continuously, and the passive joint steps. There is a difference in the phase of their rotation. f Construction of the PHO: the actuation chambers, the rotating-based bistable beam, and the switching valve. g High-speed camera images of one oscillation period with a rotation period of 19 ms.
