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A Modified Lean and Release Technique to Emphasize Response Inhibition and Action Selection in Reactive Balance
Published on: March 19, 2020
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Exoskeletons need to react faster than physiological responses to improve standing balance
Owen N Beck1,2, Max K Shepherd3,4, Rish Rastogi2
1Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, USA.
Science Robotics
|February 15, 2023
Summary
Wearable exoskeletons improve balance when reacting faster than human physiological responses. Exoskeleton torque delivered before natural muscle activity enhances stability, unlike delayed reactions.
Area of Science:
- Biomechanics
- Robotics
- Human-Computer Interaction
Background:
- Maintaining balance is crucial for daily activities but challenging due to human physiological reaction time limitations.
- Wearable exoskeletons offer potential to enhance balance by reacting faster than humanly possible.
- However, the timing of exoskeleton assistance can interfere with natural user responses, potentially hindering balance recovery.
Purpose of the Study:
- To investigate the optimal timing of exoskeleton assistance for improving reactive balance control after postural disturbances.
- To determine if artificially fast exoskeleton responses are necessary to enhance standing balance.
- To understand how exoskeleton torque timing affects physiological responses and sensory feedback.
Main Methods:
- Participants performed balance tasks while wearing an ankle exoskeleton capable of delivering controlled torque.
- Exoskeleton torque was applied at different time points relative to physiological responses during postural perturbations.
- Measurements included joint moments, muscle activity (soleus), and center of mass (CoM) kinematics.
Main Results:
- Ankle exoskeleton torque applied before physiological joint moments improved standing balance by 9%.
- Delayed torque application, coinciding with physiological responses, did not improve balance.
- Artificially fast torque minimally reduced soleus muscle activity but disrupted local ankle mechanics; whole-body mechanics (CoM velocity) better predicted muscle activity.
Conclusions:
- Exoskeletons must react faster than physiological responses to effectively improve standing balance.
- Optimal human-exoskeleton balance control may require device torque informed by global sensory feedback (e.g., CoM kinematics) that precedes physiological reactions.
