Lightweight Control Method for Dielectric Elastomer Actuators as Self-Sensing Artificial Muscles

The desire to develop artificial muscles which can mimic biological behaviors and are accessible for medical or industrial applications require a suitable technology. For this purpose dielectric elastomers represent a promising technology, which can transform electrical energy into mechanical energy. They have promising properties which are similar to human muscles like high energy density, good weight-to-power ratio, high efficiency, inherent flexibility and good elastic strains. Dielectric elastomers can not only be used as actuators, but also as flexible sensors. A further key feature is the capability to measure the current actuation state without external sensors while the actuator is driven. Therefore, only one single element is sufficient for actuation and sensing. This paper describes an approach to implement this self-sensing capability in a lightweight control method by superimposing the driving voltage and the signal for measuring the contraction. Additional components like heavy external function generators or measurement equipment are not required which reduces complexity and weight of the setup and therefore enables mobile applications such as future prostheses or soft robots. A series of experiments of different modes with active and passive deformation is used for validating the self-sensed capacitance, which is compared to a camera system based capacitance measurement. The overall performance of the self-sensing system with active and passive deformation of the actuator is discussed.