SIMULTANEOUS CONTROL OF AN ANKLE-FOOT PROSTHESIS MODEL USING A VIRTUAL CONSTRAINT.

Area of Science:

• Robotics
• Biomechanics
• Prosthetics Control

Background:

• Current robotic prostheses for amputee locomotion face control system design challenges.
• Existing methods discretize the gait cycle, requiring real-time phase identification and parameter tuning, which limits practical implementation.
• Robotic approaches using phase variables and virtual constraints offer whole-gait cycle characterization but are difficult to apply to prosthetics due to measurement and parameter variability.

Purpose of the Study:

• To design a robust and simplified controller for robotic ankle prostheses.
• To overcome limitations of existing control methods by avoiding reliance on hard-to-measure quantities and variable prosthesis parameters.
• To enforce a virtual constraint for stable amputee locomotion using a novel control approach.

Main Methods:

• Utilized the simultaneous stabilization approach to design a controller.
• Developed a low-order, linear time-invariant controller for ankle prostheses.
• Enforced a virtual constraint independent of user-prosthesis interaction forces and prosthesis parameters.

Main Results:

• The designed controller demonstrated suitable walking gaits in simulations for a simplified amputee model.
• The controller's independence from specific interaction forces and prosthesis parameters simplifies its application.
• The simultaneous stabilization approach proved effective for prosthetic ankle control.

Conclusions:

• A novel controller based on simultaneous stabilization can effectively manage robotic ankle prostheses for amputee locomotion.
• This approach offers a more practical solution compared to existing methods by eliminating the need for complex real-time measurements.
• The controller's design shows promise for improving the stability and usability of prosthetic devices.