A Novel Approach to Muscle Control for in vitro Gait Simulators.

Area of Science:

• Biomechanics
• Robotics
• Orthopedics

Background:

• In vitro gait simulators are crucial for replicating in vivo foot and ankle biomechanics.
• The control system significantly impacts the fidelity of these simulations.
• A physiologically accurate six-segment, nine-tendon phantom model was developed.

Purpose of the Study:

• To compare the accuracy and speed of two control systems for an in vitro gait simulator.
• To evaluate controller performance on both range-of-motion and physiological gait tasks.

Main Methods:

• Developed a six-segment, nine-tendon phantom model for in vitro gait simulation.
• Tested a three-stage cascade controller and a force controller.
• Evaluated controllers on sinusoidal and stance-phase gait motion trials.

Main Results:

• The cascade controller exhibited higher accuracy (0.27° ± 0.01° vs. 0.66° ± 0.11° average error) and repeatability.
• The force controller was faster (19.0 ms ± 4.1 ms vs. 57.4 ms ± 12.6 ms loop time).
• Both systems achieved high linear correlation (r > 0.99).

Conclusions:

• Both control systems offer high accuracy and repeatability in gait simulation.
• Controller selection should be based on study-specific requirements for speed versus precision.
• Accurate in vitro simulators aid in understanding and treating foot/ankle pathologies.