Friction Characterization of a Cable-Driven Differential Actuation System for Lower-Limb Exoskeletons

Abstract:Lower-limb exoskeletons require actuation systems that can provide accurate joint torque control while preserving low mass and encumbrance. Conventional architectures often rely on independently actuated joints and joint-level torque sensors, increasing system complexity and weight. This paper presents a novel differential actuation architecture for hip-knee flexion/extension, enabling cooperative torque sharing between two motors via a linear differential mapping between motor and joint. To compensate for transmission losses, a model-based friction estimation strategy is developed and experimentally implemented, allowing accurate joint torque estimation without the need for torque sensors. The proposed solution is validated on a physical prototype, demonstrating the feasibility of sensorless torque estimation in a differentially actuated hip-knee module of a lower-limb exoskeleton.

Robotics (cs.RO); Systems and Control (eess.SY)

arXiv:2606.15997 [cs.RO]

(or arXiv:2606.15997v1 [cs.RO] for this version)

https://doi.org/10.48550/arXiv.2606.15997 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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