Foot-to-Forearm Tactile Feedback for Lower-Limb Exoskeleton Control: A Pilot Benchmarking Study in Healthy Adults

Area of Science:

• Biomechanics
• Neurorehabilitation
• Human-Computer Interaction

Background:

• Exoskeleton-based neurorehabilitation utilizes tactile feedback, like Foot-to-Forearm Feedback (FFF), particularly for spinal cord injury patients.
• The impact of FFF on healthy individuals navigating diverse terrains with lower-limb exoskeletons is not well-documented.

Purpose of the Study:

• To investigate the effects of FFF on objective biomechanical measures and subjective user experience in healthy individuals controlling a lower-limb exoskeleton across various terrains.
• To assess the feasibility and potential benefits of FFF in non-rehabilitation contexts.

Main Methods:

• A pilot study involved seven healthy participants controlling a lower-limb exoskeleton under two conditions: with and without FFF.
• Participants navigated five scenarios: Flat, M-Shape, A-Shape, V-Shape, and Random.
• Objective data (step count, sacroiliac joint segment length/angle) and subjective feedback (preference, Global Experience Index) were collected.

Main Results:

• No consistent significant differences were found in objective measures (step count, SIJ kinematics) between the control and FFF conditions.
• Despite objective similarities, 71.4% of participants preferred the FFF condition overall.
• Subjective preference for FFF varied by scenario, with higher preference on Flat terrain and lower on Random terrain. FFF partially mitigated Global Experience Index score reductions in the A-Shape scenario.

Conclusions:

• Foot-to-Forearm Feedback (FFF) may enhance the subjective experience of healthy users operating lower-limb exoskeletons, particularly on varied terrains.
• While objective biomechanical effects were not consistently observed in this pilot study, the positive subjective feedback warrants further investigation.
• Larger sample sizes and refined experimental designs are necessary to confirm the influence of FFF on user experience and its potential applications.