Novel method to form adaptive internal impedance profiles in walkers

Area of Science:

• Robotics
• Biomechanics
• Control Systems

Background:

• Traditional prosthetic and robotic walking systems often rely on closed-loop controllers, which can be complex and sensitive to environmental uncertainties.
• Developing open-loop control strategies that adapt in real-time is crucial for robust locomotion in unpredictable terrains.

Purpose of the Study:

• To propose and validate a novel open-loop control approach for improving walking in prosthetics, orthotics, and robotics.
• To demonstrate the effectiveness of real-time impedance profile updates for environmental adaptation without closed-loop systems.

Main Methods:

• Developed an approach using state feedback to update impedance profiles in real-time via a simple policy.
• Investigated transient and steady-state gaits using two update policies (velocity control and peak force minimization) on a passive dynamic walker (rimless wheel).
• Implemented damping profiles in a motor analogous to a knee joint for the rimless wheel.

Main Results:

• Simulation results indicate the velocity update equation effectively handles varying ground conditions within operational limits.
• Experimental results confirm that the average angular velocity reached the target.
• The peak force update equation successfully reduced peak collision forces in real-time experiments.

Conclusions:

• The proposed open-loop approach enables adaptive walking in uncertain environments by dynamically adjusting impedance profiles.
• This method offers a simpler, more robust alternative to closed-loop controllers for robotic locomotion.
• The findings have implications for developing more adaptable and resilient prosthetic and robotic walking systems.