Human arm weight compensation in rehabilitation robotics: efficacy of three distinct methods

Journal of NeuroEngineering and Rehabilitation, 2020 · DOI: https://doi.org/10.1186/s12984-020-0644-3 · Published: January 19, 2020

Assistive Technology

Simple Explanation

The study introduces criteria for ideal arm weight compensation in rehabilitation robotics. Three distinct arm weight compensation methods (Average, Full, Equilibrium) are proposed and analyzed within the ARMin exoskeleton. The study validates the effect of the best-performing method in chronic stroke subjects to increase the active range of motion.

Study Duration

Not specified

Participants

31 healthy subjects, 3 chronic stroke patients

Evidence Level

Not specified

Key Findings

1
All three arm weight compensation methods reduced the mean EMG activity of healthy subjects compared with the no compensation reference.
2
The Equilibrium method outperformed the Average and the Full methods with a highly significant reduction in mean EMG activity.
3
Horizontal workspace assessment in poststroke patients with the Equilibrium method revealed potential workspace size-dependence of arm height.

Research Summary

Different arm weight compensation methods were developed according to initially defined criteria and analyzed with respect to sensitivity and required technology. Weight compensation performance improved with the level of technology, but increased cost and calibration efforts. The feasibility of the best method, Equilibrium, was shown by testing with three stroke patients, highlighting the importance of patient-specific weight compensation.

Practical Implications

Systematic Analysis Method

The study reports a systematic way to analyze the efficacy of different weight compensation methods using EMG, providing a valuable tool for future research and development.

Height Dependence Consideration

The height dependence of workspace size suggests the importance of patient-specific weight compensation, particularly for training at different arm heights, which should be considered in rehabilitation programs.

Method Selection Considerations

Each method has its own individual advantages such as in set-up time, cost, or required technology. Therefore, the advantages can be weighted against the performance for specific applications.

Study Limitations

1
The study's workspace analysis with stroke patients involved only three subjects, limiting the generalizability of the findings regarding height-dependent effects.
2
Passive joint torques and misalignment effects between the arm and the robot are identified as potential confounding factors, suggesting the need for further research to minimize their influence.
3
The Full method's estimation process is sensitive to forces/torques caused by passive joint torques and misalignment, potentially limiting its practical application.

Your Feedback

Was this summary helpful?

Back to Assistive Technology