Development of VariLeg, an exoskeleton with variable stiffness actuation: first results and user evaluation from the CYBATHLON 2016

Journal of NeuroEngineering and Rehabilitation, 2018 · DOI: https://doi.org/10.1186/s12984-018-0360-4 · Published: March 1, 2018

Spinal Cord Injury Assistive Technology

Simple Explanation

The VariLeg exoskeleton is a powered lower limb device designed to help people with spinal cord injuries walk. It uses a variable stiffness actuation (VSA) unit in the knee joint. The exoskeleton was tested with two users who trained for four months to participate in the CYBATHLON 2016 competition. The CYBATHLON served as a real-world test of the exoskeleton's usability, where the user was able to complete 3 out of 6 obstacles.

Study Duration

4 Months

Participants

2 paraplegic users with motor complete thoracic lesions at Th4 and Th12

Evidence Level

Not specified

Key Findings

1
The variable stiffness actuation system in the knee joint could be rendered with an error lower than 30 Nm/rad.
2
Users acquired proficient skills in basic balancing, walking, and slalom walking during training.
3
One user was able to perform 3 out of 6 obstacles of the CYBATHLON track after 4 months of training.

Research Summary

The VariLeg exoskeleton is a powered lower limb exoskeleton with a variable stiffness actuator (VSA) in the knee joint, designed to assist individuals with motor complete spinal cord injuries (SCI) in performing daily mobility tasks. Two users with thoracic motor complete SCI participated in a four-month training program to evaluate the feasibility and usability of the exoskeleton, culminating in participation in the CYBATHLON 2016 competition. The study demonstrated the applicability of the VariLeg exoskeleton to restore ambulation for people with motor complete SCI, highlighting the importance of training and experience in piloting such devices.

Practical Implications

Assistive Device Development

The VariLeg exoskeleton demonstrates potential as an assistive device for individuals with spinal cord injuries, particularly in restoring ambulation and performing daily tasks.

Training Protocols

The study emphasizes the importance of comprehensive training programs for users of powered exoskeletons, including balance training, gait adjustments, and task-specific practice.

VSA Technology

The variable stiffness actuation system shows promise for improving the robustness and adaptability of exoskeletons, potentially leading to more efficient and stable walking on uneven terrain.

Study Limitations

1
Limited sample size of two participants.
2
The variable stiffness actuation was used in a fixed stiffness mode during the training and competition due to time constraints.
3
The assessment of skill level was subjective to some degree, as it was not based on clinical assessments and no fixed protocol was followed to assess the skill.

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