Adaptive Cooperative Control for Hybrid FES-Robotic Upper Limb Devices: a Simulation Study

Area of Science:

• Biomedical Engineering
• Rehabilitation Robotics
• Neurorehabilitation

Background:

• Robotic systems and Functional Electrical Stimulation (FES) are key in motor rehabilitation but have limitations.
• Hybrid systems combining robots and FES offer synergistic benefits for joint rehabilitation.

Purpose of the Study:

• To develop and evaluate a novel adaptive cooperative controller for upper limb rehabilitation.
• To integrate motor torque allocation based on muscle fatigue estimation with FES and robotic impedance control.

Main Methods:

• A novel adaptive cooperative controller was designed, featuring an allocator for torque distribution, an FES closed-loop controller, and a robotic impedance control loop.
• The controller was simulated for elbow flexion/extension movements, assessing motor torque, trajectory tracking, and fatigue management.

Main Results:

• The hybrid controller reduced motor torque requirements compared to a robot-only approach, with a slight trade-off in trajectory tracking.
• The system demonstrated improved fatigue management compared to an FES-only approach.
• The allocator effectively managed fatigue-related phenomena by adjusting FES and motor contributions.

Conclusions:

• The proposed adaptive cooperative controller offers a balanced solution for upper limb rehabilitation, optimizing motor torque consumption and trajectory tracking.
• The allocation strategy is effective in mitigating both motor torque and FES-induced muscle fatigue.
• This approach presents a promising solution for hybrid FES-robotic rehabilitation systems.