Development of an ankle joint assist suit with a velocity-based safety device (Detailed design)

In the design of rehabilitation assist suits, safety consideration for patients is one of the most important issues. We have proposed the basic structure of an ankle joint assist suit with a velocity-based safety device. The velocity-based safety device is intended to stop the assist suit if it detects an unexpected high joint angular velocity. This safety device is designed to work even when the computer breaks down, because it consists of only passive mechanical components without actuators, controllers, and/or batteries. In this paper, we introduce the detailed design of the important parts (motor, gear, torsion spring, encoder, and velocity-based safety device) in the assist suit. First, the design specification of the assist suit is described. Next, the structure of the assist suit is explained. Finally, the detailed design is presented.