Altering gait variability with an ankle exoskeleton.

Area of Science:

• Biomechanics
• Robotics
• Human-Computer Interaction

Background:

• Human gait exhibits inherent variability, crucial for stability.
• Unhealthy gaits often show increased variability.
• Exoskeleton influence on gait variability remains under-investigated.

Purpose of the Study:

• To investigate how exoskeleton timing and power affect gait variability.
• To identify specific parameters that reduce or increase gait variability.
• To explore the potential of exoskeletons in gait rehabilitation.

Main Methods:

• Ten healthy participants walked on a treadmill with bilateral ankle-foot exoskeletons.
• Ten conditions with varied timing (36%-54% stride) and power (0.2-0.5 W·kg⁻¹) were tested.
• Gait variability was quantified using the largest Lyapunov exponent (LyE) and maximum Floquet multiplier (FM).

Main Results:

• Lowest LyE at the ankle was achieved with 0.45 W·kg⁻¹ power and 48% stride timing.
• Exoskeleton power and timing interactions significantly affected LyE at the knee and hip.
• Ankle FM increased with higher power and later timing; knee FM was influenced by power and timing interactions.

Conclusions:

• Exoskeleton assistance can reduce gait variability, particularly at the ankle joint.
• Specific parameter combinations offer potential for gait modulation.
• Findings suggest exoskeletons could be valuable rehabilitation tools for gait disorders.