Patent ID: 8690801

Claim:
A leg assist device that assists standing up motion of a user, the leg assist device comprising: an upper leg link to be attached to an upper leg of the user; a lower leg link to be attached to a lower leg of the user; a rotary joint that connects the lower leg link to the upper leg link, the rotary joint having an actuator that rotates the lower leg link; and a controller having a feed-back control module that computes a command torque for the actuator based on a difference between a lower leg link angle and a target angle, the controller controls the actuator so that the lower leg link angle matches the target angle; wherein: the controller has a torque limiter that limits magnitude of the command torque computed by the feed-back control module; the controller sets the target angle to a standing position angle corresponding to a user's standing position; and the controller raises an upper limit of the torque limiter as a user's hip height rises.