A walker-pusher inchworm actuator driven by two piezoelectric stacks

Most of inchworm piezoelectric actuators suffer from complicated structures and control systems due to the utilization of three or more piezoelectric stacks. Various approaches have been further developed to reduce the piezoelectric stacks. However, output characteristics loss remains an inevitable problem. Here, we present an inchworm actuator driven by two piezoelectric stacks with large carrying capacity and no backward motion which inherits advantages of the traditional inchworm piezoelectric actuators. Correspondingly, each clamping foot can be converted into a clamping unit or an extension unit utilizing a distinctive double-diamond flexure hinge. An approach utilizing the parasitic motion to realize the walker-pusher mode was proposed. Experimental results indicate that no-backward linear motion can be realized by walker-pusher mode, which utilizes the parasitic motion. The actuator achieved a maximum speed of 471.01 μm/s, a carrying load of 6.1 kg and an output force of 11.76 N when the frequency and voltage were 19 Hz and 150 V. This work confirms that it is feasible to design inchworm actuator driven by two stacks working in walker-pusher mode with no backward motion.