Accelerometry-enabled measurement of walking performance with a robotic exoskeleton: a pilot study

Journal of NeuroEngineering and Rehabilitation, 2016 · DOI: 10.1186/s12984-016-0142-9 · Published: March 22, 2016

Spinal Cord Injury Assistive Technology Rehabilitation

Simple Explanation

Clinical scores for evaluating walking skills with lower limb exoskeletons are often based on a single variable, such as distance walked or speed, even in cases where a host of features are measured. We investigated how to combine multiple features such that the resulting score has high discriminatory power, in particular with few patients. A new score is introduced that allows quantifying the walking ability of patients with spinal cord injury when using a powered exoskeleton.

Study Duration

6 to 12 weeks

Participants

4 spinal cord injury patients and 7 expert users

Evidence Level

Not specified

Key Findings

1
All 4 patients improved over the course of training, as their scores trended towards the expert users’ scores.
2
The combined score (Gaussian naïve surprise) was considerably more discriminative than the one using only walked distance (steps).
3
At the end of training, 3 out of 4 patients were significantly different from the experts, according to the combined score

Research Summary

We investigated how to combine multiple features such that the resulting score has high discriminatory power, in particular with few patients. A new score is introduced that allows quantifying the walking ability of patients with spinal cord injury when using a powered exoskeleton. Integrating multiple features could provide a more robust metric to measure patients’ skills while they learn to walk with a robotic exoskeleton.

Practical Implications

Improved Clinical Decision-Making

A discriminatory score with increased sensitivity can better support clinicians’ decisions on whether a participant needs more training or is ready to use the robotic exoskeleton at home.

Enhanced Training Programs

Insights into patients’ learning curves could guide the design of future exoskeletons and the planning of training sessions.

Objective Assessment of Exoskeleton Performance

The proposed approach of constructing an index of walking performance could be applied to any other situation where expert performance is measured along with existing performance.

Study Limitations

1
Study with a larger pool of subjects is crucial to validate the results and remains as future work.
2
Only 4 features from the trunk accelerations to evaluate walking quality were computed; incorporating other features could capture additional factors that affect walking skills with the exoskeleton.
3
Ideally the features should be independent, which is not true in our case, as the standard deviation of the trunk tilt and the acceleration counts are expected to be strongly correlated.

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