A self-switching bistable artificial muscle actuator

We present a self-motivating and self-switching bistable structure using bending actuators or artificial muscles. By exploiting the inherent bi-stability in buckled beam and buckled plate structures we have designed a bistable actuator that requires no energy to maintain either of the two stable states. In addition to bistable characteristics we show how such a structure, if constructed from a bending actuator (artificial muscle) such as ionic polymer metal composites (IPMC), may actively switch itself between stable states. Thus the self-switching bistable actuator is an extremely simple and elegant design that requires none of the external actuating mechanics traditionally used. In the analysis we consider the nature of bistable buckled beams and their internal stresses and we propose actuating schema for the movement from one stable state to another. We show how segmentation of a strip actuator can be matched to the desired bistable structure and the intended switching motion. We consider the characteristic buckling modes of axially compressed beams and show how these can suggest efficient control and switching mechanisms. We also present some example applications from the micro-scale upwards, including a tactile display device.