Study of the contraction characteristics of a large-scale stacked-type electrostatic actuator

Electrostatic actuators have some advantages such as the light weight and the high energy efficiency, and these characteristics are suitable for use as artificial muscles. Traditional electrostatic actuators, however, cannot have long strokes and large force at the same time because the electrode intervals widen beyond necessity. This paper presents a large-scale stacked-type electrostatic actuator (LSEA) which was developed for use as artificial muscles of robots and power assist suits. LSEA is a multiply-stacked electrostatic actuator, and can contract linearly by the application of a voltage. It has a unique structure which can prevent the electrode intervals from overextending. It is therefore possible to have long stroke and large force at the same time. In experiments, the contraction characteristics as a function of applied voltage, load weight and elapsed time was measured. The measurements revealed LSEA achieved the contraction ratio equivalent to that of a muscle and also can have a high actuation energy density.