IEEE Trans Med Robot Bionics, 2020 · DOI: 10.1109/TMRB.2020.2977416 · Published: May 1, 2020
This paper introduces a new way to control hybrid exoskeletons, which combine functional electrical stimulation (FES) and powered assistance to help people with spinal cord injuries (SCI) stand up. The control system is designed to optimally distribute the workload between FES and the exoskeleton's motors, taking into account muscle fatigue. The control system uses a hierarchical approach. A high-level controller ensures the user follows the desired standing-up motion, while a low-level controller optimally allocates the knee torque between FES and the electric motor, considering muscle fatigue dynamics. Experiments were conducted on participants with and without disabilities to validate the control system. The results showed the hierarchical control design is a promising method to effect shared control in a hybrid exoskeleton.
The hybrid exoskeleton system can potentially improve rehabilitation outcomes for individuals with SCI by providing personalized and dynamically adjusted assistance during standing-up movements.
By optimally allocating control between FES and electric motors based on muscle fatigue dynamics, the system can help delay the onset of muscle fatigue and maximize active muscle exercise.
The hybrid system has the potential to reduce power consumption compared to purely powered exoskeletons, which could extend battery life and improve the practicality of these devices.