A High Performance Muscle-like Actuator using Multi-layer Electrostatic Film Motors

Artificial muscles have been researched for decades; however, most of them have difficulty in control with high accuracy due to nonlinearity, such as hysteresis and creep phenomenon. On the other hand, electrostatic film motors have fine controllability, as well as high performance, flexibility and high accuracy, and are excepted to be used in robotics. The rigid prototype developed in a previous work had low force-to-weight ratio due to its bulky structure, while another flexible prototype only provided 4.5 N due to its small size and few layers. This paper reported a new muscle-like actuator with high force-to-weight ratio using multi-layer electrostatic film motors, in which 11 pairs of double-sided drive films were assembled together. Experiments were carried out under two conditions, static and dynamic, in which the force performance was evaluated using a load cell, or by lifting a weight, respectively. The prototype weighing 235 g recorded a force of 163 N under voltage of 1.8 kV and lifted around 4 kg weight under voltage of 1.3 kV. Compared with the existing structure with similar sizes, the prototype in this work has 4.7 times larger force-to-weight ratio.