Mechanical Design, Control, and Laboratory Test of a Two-Degrees-of-Freedom Elbow Prosthesis.

Area of Science:

• Biomedical Engineering
• Robotics
• Prosthetics Design

Background:

• Human elbow prostheses aim to restore natural movement.
• Existing control methods may not fully replicate native elbow kinematics.
• Advanced control strategies are needed for improved prosthetic function.

Purpose of the Study:

• To design and test a 2-DOF elbow prosthesis prototype.
• To compare the performance of Proportional-Integral-Derivative (PID) control and Sliding Mode Control with Time Base Generator (SMC + TBG) strategies.
• To evaluate the biomimetic capabilities of the prosthesis under different control methods.

Main Methods:

• A 2-DOF elbow prosthesis was mechanically designed using 3D-printed parts and custom joints with worm and pinion gear transmissions.
• Real-time monitoring and control were achieved using voltage and current sensors.
• Laboratory tests compared PID and SMC + TBG control strategies based on angular displacement and velocity metrics.

Main Results:

• The prosthesis achieved a range of motion of 100-120° for flexion-extension, 50° for supination, and 75° for pronation.
• SMC + TBG control demonstrated biomimetic angular displacement and velocity patterns.
• PID control did not replicate the natural movement patterns of the human elbow.

Conclusions:

• The developed 2-DOF elbow prosthesis effectively replicates human elbow movement patterns.
• The SMC + TBG control strategy is superior to PID for achieving biomimetic motion in elbow prostheses.
• This advanced prosthetic control shows promise for individuals with transhumeral amputations.