The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: A Case Series

Area of Science:

• Biomechanics
• Robotics
• Human-computer interaction

Background:

• Exoskeletons require effective terrain adaptability for real-world use, particularly on inclines.
• Previous studies focused on single-joint assistance; whole-leg assistance shows promise for greater improvements.

Purpose of the Study:

• To determine optimal whole-leg exoskeleton assistance strategies for minimizing metabolic cost during incline walking.
• To investigate how exoskeleton assistance should adapt to varying inclines.

Main Methods:

• Human-in-the-loop optimization was employed to identify assistance torques.
• Three participants walked on 5°, 10°, and 15° inclines using a hip-knee-ankle exoskeleton emulator.
• Metabolic cost was measured to evaluate assistance effectiveness.

Main Results:

• Assisted incline walking reduced the cost of transport by at least 50% compared to unassisted walking.
• Optimized torque and power demands increased with steeper inclines.
• Applied exoskeleton power on steep inclines was double that of level-ground walking.

Conclusions:

• Whole-leg exoskeleton assistance can substantially improve incline walking efficiency.
• Future exoskeletons need sufficient torque and power capabilities to maximize benefits across diverse inclines.
• Optimized assistance strategies are crucial for enhancing exoskeleton performance in varied environments.