Perception of Powered Ankle Exoskeleton Actuation Timing During Walking: A Pilot Study

Area of Science:

• Biomechanics
• Human-Computer Interaction
• Robotics

Background:

• Actuation timing is critical for powered ankle exoskeleton performance and user experience.
• Previous research focused on optimizing timing for metabolic cost, neglecting human perception.
• Understanding user perception of actuation timing is crucial for effective exoskeleton design.

Purpose of the Study:

• To quantify human sensitivity to variations in powered ankle exoskeleton actuation timing.
• To determine the just-noticeable difference (JND) threshold for actuation timing perception.
• To explore individual differences in perceiving exoskeleton control parameters.

Main Methods:

• A pilot study involving two subjects walking with a powered ankle exoskeleton.
• Utilized psychometric functions to determine the JND threshold for actuation timing discrimination.
• Measured subjects' ability to detect small changes in actuation timing relative to stride period.

Main Results:

• Subjects demonstrated sensitivity to actuation timing variations.
• JND thresholds were found to be 3.6% and 6.8% of the stride period for the two subjects.
• Significant individual differences in perceptual sensitivity were observed.

Conclusions:

• This study provides initial insights into human perception of exoskeleton actuation timing.
• Findings suggest that exoskeleton control parameters should consider individual user differences.
• Results inform precision requirements for exoskeletons to enhance human-system interaction and user acceptance.