Biarticular Rigid Powered Lower Extremity Exoskeleton Robot
Tianchi Chen, Zhi Liu, Chaoyang Li, Xiaoan Chen, Jianjun Hu, Jiaxun Wu, Ye He
AI summary
Problem
Conventional monoarticular lower limb exoskeletons suffer from joint misalignment, actuator redundancy, and added distal mass, which disrupt natural gait and limit efficiency.
Approach
The researchers designed a rigid biarticular exoskeleton that uses one actuator and a linkage to simultaneously assist the knee and ankle, guided by a hierarchical controller that recognizes gait phases and generates phase-specific torque with gravity and friction compensation.
Key results
- Up to 63.4% reduction in gastrocnemius activation during stair ascent
- Up to 11.6% decrease in metabolic cost during stair climbing and 8.2% during level walking
- 96.8% accuracy in real-time gait phase recognition using a neural network
- Effective gravity and friction compensation enabling stable, phase-specific assistance
Why it matters
Provides a compact, biomechanically aligned alternative to traditional exoskeletons, advancing practical wearable robotics for rehabilitation and mobility augmentation.
Abstract
Lower extremity exoskeletons designed for multi-joint assistance are increasingly explored for rehabilitation and human augmentation. However, conventional monoarticular designs often suffer from joint misalignment and actuator redundancy, limiting their efficiency and user comfort. This study presents a biarticular rigid powered lower extremity exoskeleton that simultaneously assists the knee and ankle joints through a single actuator, enabling coordinated torque generation across adjacent joints. A hierarchical control framework combining gait segmentation, impedance-based torque generation, and gravity/friction compensation is implemented to provide phase-specific assistance. Experimental results show that the proposed exoskeleton reduces gastrocnemius activation by up to 63.4% and metabolic cost by up to 11.6% during stair ascent, with corresponding reductions of 28.3% and 8.2% during level walking. These findings demonstrate the effectiveness of the biarticular and underactuated structure in enhancing locomotor efficiency, highlighting its potential as a compact and practical solution for dynamic and diverse mobility scenarios.