Automatic Control of Prosthetic Socket Size for People WithTranstibial Amputation: Implementation and Evaluation

Area of Science:

• Biomedical Engineering
• Rehabilitation Engineering
• Prosthetics and Orthotics

Background:

• Maintaining optimal prosthetic socket fit is crucial for comfort and function in individuals with transtibial amputation.
• Current prosthetic sockets often require manual adjustments to accommodate changes in limb volume, which can be inconvenient for users.

Purpose of the Study:

• To design, implement, and test an automated control system for a motor-actuated, cable-panel prosthetic socket.
• To continuously adjust socket size and maintain optimal prosthetic fit.

Main Methods:

• Fabricated motor-driven adjustable sockets for participants with transtibial amputation.
• Implemented a proportional-integral control system using Socket Fit Metric (SFM) data from an embedded inductive sensor.
• Tested system performance during treadmill walking to assess set point maintenance and response to changes.

Main Results:

• The control system demonstrated high accuracy in maintaining a set point, with a median Integral of Absolute Error (IAE) of 0.003 mm.
• Response to set point changes also showed minimal error, with a median IAE of 0.003 mm.
• A median error of 0.003 mm corresponded to a clinically acceptable 0.08% socket volume error.

Conclusions:

• The developed control system is capable of maintaining and responding to changes in prosthetic socket fit.
• The system's performance indicates readiness for further evaluation outside laboratory settings.
• This technology has the potential to significantly improve the quality of life for prosthesis users by eliminating the need for manual socket adjustments.