Xomino: A One-Way Self-Locking Clutched Actuator for Soft Textile-Based Materials

• Published in: IEEE/ASME transactions on mechatronics Vol. 30; no. 4; pp. 3019 - 3027
• Main Authors: Pitzalis, Roberto F., Bozano, Giacomo, Lambranzi, Chiara, Caldwell, Darwin G., Berselli, Giovanni, Ortiz, Jesus
• Format: Journal Article
• Language: English
• Published: IEEE 01.08.2025
• Subjects: Actuators; Clutched actuators (CAs); Exoskeletons; Force; Friction; Kinematics; Motors; Pins; Robots; self-locking mechanisms; soft clutch; Vectors; Wearable devices; webbing clutch
• ISSN: 1083-4435; 1941-014X
• DOI: 10.1109/TMECH.2025.3570015

The presented clutch mechanism works with textile-based materials having a rectangular shape. All mechanical components are 3-D printed in acrylonitrile butadiene styrene, a strong plastic polymer. It consists of a series of pivoted plates with rectangular apertures through which a webbing passes. Due to the push-pull effect of a small linear motor, the plates can move back and forth by gripping and releasing the webbing, respectively. The engagement and disengagement of the clutch is completely controllable. Moreover, once engaged, the clutch can adapt to the external load: its gripping force increases as the load increases due to the movable and adaptable arrangement of the motor fixations. Elastic bands, anchored to the motor base, allow the motor to return to its initial position, guaranteeing clutch disengagement even under loads. Four different tests are performed: a static tensile test up to 250 N, a cyclic tensile test from 0 to 200 N, an unlocking text under load, and a tensile failure test. Xomino shows prominent performance, as it can hold up to 350 N without breaking or slipping. It has been integrated in a hip exoskeleton prototype and validated on a subject to provide assistance while walking.