Design and control of the MINDWALKER exoskeleton

Area of Science:

• Robotics
• Biomechanics
• Rehabilitation Engineering

Background:

• Paraplegics require assistive devices for ambulation.
• Existing powered exoskeletons often lack sufficient control for dynamic balance, particularly in the frontal plane.
• Active hip ab/adduction (HAA) is crucial for weight shifting and lateral stability during walking.

Purpose of the Study:

• To design, control, and evaluate a novel powered exoskeleton, MINDWALKER, with active HAA.
• To assess the efficacy of a finite-state machine controller and a step-width adaptation algorithm for gait assistance and balance control.
• To test the exoskeleton's performance in both healthy individuals and individuals with spinal cord injury (SCI).

Main Methods:

• Development of the MINDWALKER exoskeleton with powered hip and knee joints, including powered HAA, utilizing series elastic actuators.
• Implementation of a finite-state machine controller triggered by Center of Mass (CoM) displacement for state transitions.
• Introduction of a novel step-width adaptation algorithm for dynamic lateral balance stabilization.
• Testing the system on healthy subjects and paraplegics, including applying external disturbances.

Main Results:

• All users successfully initiated steps via CoM displacement.
• The step-width adaptation algorithm effectively counteracted external disturbances.
• Healthy subjects achieved stable walking without crutches.
• Paraplegics did not yet achieve stable walking without crutches, indicating a need for further improvement.

Conclusions:

• The MINDWALKER exoskeleton demonstrates potential for assisting paraplegics in walking, with effective balance control mechanisms.
• The CoM-triggered control and step-width adaptation show promise for dynamic stability.
• Further research and development are necessary to achieve stable, unassisted walking for individuals with SCI using this exoskeleton.