Development and testing of novel soft sleeve actuators

Abstract

Aging populations and the rising prevalence of neurological and musculoskeletal disorders increase the demand for wearable mobility assistive devices that are effective, comfortable, and anatomically compatible. Many existing systems use rigid mechanisms and bulky interfaces that impede force transmission and reduce wearability. This study introduces a soft sleeve actuation architecture that conforms to the limb while transmitting forces and moments efficiently. We develop three soft sleeve actuators that produce linear, bending, and twisting motion, and an omnidirectional design that combines these motions in one device. Actuators are fabricated from thermoplastic elastomers using a customized fused filament fabrication process that produces airtight and compliant structures and resolves leakage observed with conventional methods. A dedicated experimental platform quantifies kinematic outputs such as displacement, angle, and twist, and kinetic outputs such as force and torque under low pneumatic pressures. A parametric study varies geometric features and material properties to determine their influence on performance. Results show reproducible multi axis motion with improved transfer of force to the limb and reduced need for complex attachment hardware. The work establishes a unified and manufacturable framework for soft sleeve actuation that enables compact and user centered assistive technologies with enhanced kinematic and kinetic performance.