Self-sensing investigation of a dielectric elastomer actuator array

Dielectric elastomer (DE) transducers are promising candidates for the development soft cooperative actuator systems, due to their high compliance, stretchability, lightweight, and intrinsic self-sensing capabilities. By combining several DE micro-actuators and arranging them as an array, cooperative devices such as distributed loudspeakers, soft robots, and wearable devices can be created. To achieve an effective interaction among the individual actuators and accomplish a shared task, feedback control strategies are required. In the case of cooperative DE devices, a way to fulfil the demanding requirements of lightness, compactness, and flexibility is to exploit the intrinsic material self-sensing capability. Cooperative self-sensing paradigms allow several interconnected actuators to estimate their own displacement as well as the one of their neighbors based on electrical measurement only, and use this information as a feedback for implementing a cooperative control task. In this paper, we investigate for the first time a self-sensing approach for cooperative DE actuator systems. A soft array of 1-by-3 DE elements is used as case of study. Since a single soft membrane is shared across the different actuating DEs, the capacitance of each element in the array changes by a different amount depending on which DE is actuated and/or deformed. Building upon established self-sensing algorithms for single-degree-of-freedom DE actuators, we experimentally investigate the relationship between the DEs capacitive state and the array deformation state, with the goal of reconstructing the latter based on the former for different actuation patterns (corresponding to different combinations of DEs being actuated). These results will pave the way for the future development of cooperative control algorithms for interconnected DE array systems.