Robotic-Assisted Leg Stretching Techniques Facilitated by a Powered Exercise Machine and Functional Electrical...

Area of Science:

• Rehabilitation Engineering
• Biomechanics
• Robotics

Background:

• Stretching exercises are crucial for enhancing range of motion (ROM) and preventing injuries.
• Current manual stretching methods are labor-intensive and lack personalization.
• Spinal cord injury patients can benefit from stretching for spasticity management and improved ROM.

Purpose of the Study:

• To develop and assess a powered device for implementing static, active isolated (AIS), and proprioceptive neuromuscular facilitation (PNF) stretching techniques.
• To create a robust closed-loop controller for precise ROM control during stretching.
• To evaluate the feasibility of using Functional Electrical Stimulation (FES) with stretching protocols.

Main Methods:

• A powered device with a rigid pivot arm and Bowden cable was designed to control leg rotation for hamstring stretching.
• A robust kinematic closed-loop controller was developed using Lyapunov stability analysis for precise ROM tracking.
• The device integrated Functional Electrical Stimulation (FES) for AIS and PNF stretching at target ROM endpoints.

Main Results:

• The powered device successfully emulated static, AIS, and PNF stretching techniques on the hamstring complex.
• Experiments with two able-bodied individuals demonstrated the feasibility of the device's protocols.
• The controller ensured exponential tracking of the desired range of motion.

Conclusions:

• A powered device with a closed-loop controller can effectively and repeatably deliver personalized stretching protocols.
• This technology offers a promising solution for consistent and automated flexibility training.
• The system demonstrates potential for rehabilitation and performance enhancement applications.