This project focuses on the development of the design and control strategy of a novel powered hip exoskeleton that uses a series elastic actuator to provide partial assistance to the user during gait.
The control strategy is based on impedance control and is developed to provide the user with variable assistance based on the user’s interaction with the exoskeleton, empowering the user to have certain degree of control over movement yet complete their gait cycle with reduced muscular effort. The assistance provided by the exoskeleton during gait is determined by the measure of the interaction torque between user and the exoskeleton through the series elastic component.
Different assistance levels or modes are achieved by presetting gains of the control system, ranging from a ‘free mode’ or low impedance mode which does not assist the user to higher impedance modes that assist the user to a greater degree. The controller is tested on healthy subjects with different operational modes and the torque and angle profile evaluated to determine ability of the controller to fulfill criteria such as variable assistance, adaptability, compliance, safety and stability.