A Two-stage Piezo-hydraulic Linear Actuator as Artificial Muscle in Robotic Applications

Abstract:
In line with Moravec's paradox, dexterous manipulation capabilities of a human are still extremely challenging to achieve with technical means, e.g. a robotic arm. One major reason is the discrepancy between a human muscle and the typical actuators used. Extending the piezo-hydraulic actuation principle, a novel linear motor with a two-stage capability is proposed here. It can move with high speeds at no load and, similar to a human muscle, it can apply high forces while moving with lower speed. Without the use of any gearbox, but with micro-hydraulic components, a seamless two-stage transmission is achieved. Due to its high force density and high robustness, the actuator is well-suited for robotic tasks in industrial or other harsh environments. A model of the actuator is presented together with simulation results based on a first prototype outline.