Conception, command and experimental validation of a hip flexion assistive device

Due to the projected demographic shift toward an older population, and given that stroke is considered as one of the leading causes of long-terms disability, an increase in age-correlated conditions associated with pathological gait is highly expected for the coming decade. Indeed, one frequent outcome of this kind of accident is hemiplegia and even if the majority of survivors is expected to regain walking ability, gait abnormality, muscle spasms and footdrop are persistent conditions. Research on wearable robotics has already demonstrated that it can bring an exciting and innovative solution for rehabilitation of patients with locomotive impairments and it can help re-enable them to partake in activities of daily living. This work is based on a dual 4-bar mechanisms created by 3D-printing which had already been validated on testbench but not tested on patients yet. Owing to the close interaction between the exoskeleton and the patient, human-robot interface should be carefully developed with a particular consideration for safety and ergonomics. Such an interface design is described in the context of this project and its robustness is evaluated. Moreover, assuming that one of the biggest challenges related to lower extremity orthotics is to develop strategies to control them in concert with the intentions of the user and his remaining sensory-motor system and knowing that control strategies can significantly affect one exoskeleton's performance, this work is dedicated to analyze the parameters that optimize the controller. The first experiments on a healthy subject have demonstrated the importance of the different parameters on a simple proportional controller, namely the execution time, the angular velocity limitation of the motor and the current limitation. This proof of concept showed that the developed exoskeleton can be used on a subject during walking and as some areas of improvement were identified, zero force control and little assistance are expected to be easily achieved.