Twisted and coiled polymer (TCP) muscles embedded in silicone elastomer for use in soft robot

Abstract

Researchers are seeking to create robots that could conform to non-uniform objects during handling and manipulation. High performance artificial muscles are the key factors that determine the capabilities of a robot. Twisted and coiled polymeric (TCP) muscle embedded in soft silicone skin solves some of the problems of soft robots in attaining morphed structure using low voltages, contrary to other technologies such as dielectric elastomer and piezoelectric. Furthermore, the TCP actuation system does not generate noise like pneumatic systems. The TCP embedded skin shows great promise for robotics to mimic the flexible appendages of certain animals. In this paper, we present experimental results on the effect of muscle placement and the thickness of the artificial skin on the actuation behavior, which can be used as a benchmark for modeling. We demonstrate the effect of three different skin thicknesses and three different muscle locations within the skin, by taking experimental deformation data from stereo camera. In general, two modes of actuations (undulatory and bending) were observed depending on the muscle placement, skin thickness, applied voltage, and actuation time. The thinner skin showed two-wave undulatory actuation in most cases, whereas the 4 mm skins showed mixed actuation and the 5 mm skins exhibited one-wave undulatory actuation. In all cases, the increase in voltage resulted in higher magnitudes of actuation. In addition, we showed consistent strain of the TCP muscles from 18 samples from two batches that produced an average strain of 22% (batch 1) to 20% (batch 2) with standard deviation of 2.5–1.8% respectively.