A Tendon-Driven Wrist Abduction-Adduction Joint Improves Performance of a 5 DoF Upper Limb Exoskeleton -- Implementation and Experimental Evaluation
A tendon-driven wrist module reduced spillage from 56% to just 3% in trials.
Researchers from Aalborg University and collaborators have developed a compact, tendon-driven wrist abduction-adduction (Ab-Ad) joint module for the EXOTIC2 exoskeleton, a 5-degree-of-freedom upper limb rehabilitation device. The module uses a lightweight tendon-driven mechanism for abduction and spring-driven adduction, enabling active wrist support for individuals with severe motor impairments. In a study with eight non-disabled adults, the team compared wrist-enabled versus wrist-locked conditions during drinking and scratching tasks.
The results were dramatic: implementing the active wrist Ab-Ad joint cut spill incidence during drinking from 56% to 3%—a 94% reduction—and boosted leveling success for scratching from 28% to 75%, all without increasing task completion time. A preliminary feasibility test with one ALS patient also showed positive outcomes, suggesting the approach could significantly improve real-world daily living activities for those with severe motor disabilities. The paper is under review for IEEE Transactions on Biomedical Engineering.
- Spill rate dropped from 56% to 3% during drinking tasks with the active wrist joint enabled.
- Scratching task leveling success improved from 28% to 75% with wrist Ab-Ad assistance.
- Task completion time did not increase despite the added joint movement, indicating efficient integration.
Why It Matters
Active wrist support in exoskeletons could dramatically improve quality of life for individuals with severe motor impairments during daily tasks.