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Helically Wrapped Supercoiled Polymer (HW-SCP) Artificial Muscles: Design, Characterization, and Modeling

Supercoiled polymer (SCP) artificial muscles exhibit many desirable properties such as large contractions and high power density. However, their full potential as robotic muscles is challenged by insufficient strain or force generation – non-mandrel-coiled SCP actuators produce up to 10-20% strain; mandrel-coiled SCP actuators often lift up to 10-30g of weight. It is strongly desired but difficult to obtain SCP actuators that produce large strain and large force. In this paper, the design, characterization, and modeling of helically wrapped SCP (HW-SCP) actuators are presented, which can produce up to 40-60% strain and lift more than 90g of weight. By adjusting their configuration parameters, their strain and force performance can be changed. Experiments are conducted to characterize the force production, strain, and speed of HW-SCP actuators. A Preisach hysteresis model and a polynomial model are adopted to accurately capture the actuator behaviors. This work contributes to high-performance artificial muscles.