Nonlinear Characterization of a Compact Series Visco-Elastic Element for Tendon-Driven Actuation

The design of a new series-viscous-elastic (SVE) linear joint using a silicone spring is presented. The use of silicone introduces an internal damping, which enhances system performance allowing a simpler and more stable control. Moreover, it introduces compliance between the motor and the environment, enhancing safety for robotic devices interacting with humans. In this paper, the system is modeled using the Neo-Hookean material model and then characterized through experiments. A nonlinear identification model is used to build a state-dependent force estimator. The proposed solution is compact and cheap, thus being suitable for future integration in wearable assistive exoskeletons and exosuits.