Driving force assistance control for wheelchair operation using an exoskeletal robot

Cervical Cord Injury(CCI) causes a form of upper limb dysfunction. In an individual with C5-level CCI, which is the most frequent of all eight types of CCI, force can be applied in the direction of flexion by the biceps brachii, while extension force cannot be applied by the triceps brachii. Without the ability of the triceps brachii to exert this force, individuals with a C5-level CCI cannot propel a wheelchair along a carpet or sloping road. In this study, we developed a driving force assistance control system for wheelchair operation using an exoskeletal robot. We first analyzed the difference between the wheelchair operations of a healthy person and a C5-level CCI. We then designed a control model that included a user and a wheelchair. The wearer's arm was modeled as a two-link manipulator, and the extension force and hand position were estimated using the equation of motion. The estimated extension force was compared with the driving force required to operate a wheelchair with the target velocity defined at the time of flexion of an arm. We then applied the proposed method via an exoskeletal robot. The effectiveness of the proposed method is demonstrated by experimental of wheelchair operation with C5-level CCI.