Experimental Validation of a Motor�SMA Hybrid Actuation for Lightweight Wearable Robot
Jeongae Bak, Kyungjun Choi, Hyunmok Jung, Hyunuk Seo, DAEHYUN KIM
AI summary
Problem
Conventional motor-driven wearable robots are often too heavy and lack sufficient torque for daily assistance, while lightweight artificial muscle alternatives suffer from limited force output and slow response. This creates a critical gap in developing portable, high-performance wearable robotic systems.
Approach
The authors designed a parallel hybrid actuation module that integrates a standard electric motor with a shape memory alloy (SMA) linear actuator, converting the SMA's contraction into rotational assistive torque via a wire-roller mechanism.
Key results
- Hybrid actuation delivers ~3 N·m additional assistive torque across varying load conditions
- SMA torque contribution aligns with theoretical contraction force predictions
- Effective load sharing achieved without requiring larger motors or added system weight
- Experimental testbed successfully validates the feasibility of the hybrid strategy
Why it matters
This hybrid strategy provides a practical pathway for engineers and rehabilitation specialists to build lighter, higher-torque wearable robots for elderly care and mobility assistance.
Abstract
Conventional motor-driven wearable robots often suffer from increased weight and limited torque output. To address this issue, this study proposes a motor–SMA hybrid actuation approach that combines the advantages of electric motors and shape memory alloy (SMA) actuators. A dedicated testbed was developed to evaluate the proposed method under varying load conditions. Experimental results show that the SMA actuator provides additional assistive torque of approximately 3 N·m compared to motor-only operation, without significant increase in system weight. These results demonstrate the feasibility of hybrid actuation for achieving lightweight and high-performance wearable robotic systems.