Clutchable Soft Actuators Produce Rapid, High-Power Movements in Robotic Artificial Musculoskeletal Systems

Abstract

Soft robotic actuators present tradeoffs between mechanical compliance and practical capabilities, motivating new actuation strategies that harness the storage and rapid release of elastic energy for high-performance movements. We present a servo-driven, soft linear actuator that integrates compact mechanical clutches with architected elastomers based on handed shearing auxetics (HSAs). The actuator stores elastic strain energy during servo-driven HSA extension that can be released upon clutch disengagement to drive rapid contraction. Altogether, the actuator achieves a max pulling force of 184 N, actuation strain of 23%, and contraction speed of 1.55 m s-1. A comparative characterization of performance with and without clutching reveals a nearly ten times increase in peak power with clutch-enabled actuation, while maintaining intrinsic compliance and back-drivability. When integrated into an artificial musculoskeletal system like a human-scale robot leg, the actuators enable dynamic tasks through clutch disengagement, such as ball kicking and ground push-off. Rapid clutch re-engagement can also stabilize motion by suppressing rebound oscillations. We evaluate the leg’s performance in these tasks, including transferred mechanical work, energy efficiency, and force ouput. The results demonstrate the actuator’s ability to generate fast, powerful motions and potential to advance artificial musculoskeletal systems for bioinspired robots.