Realizing an ideal impedance control system in lower extremity rehabilitation systems is challenged by mechanical impedance of robot hardware. Although many researchers in Robotics and
Control Systems have studied to reduce the mechanical impedance of actuators, they have not been able to eliminate the inertia of robot hardware. This paper introduces an alternative design using mechanical links. The mechanical links are driven by one actuator without any complicated servo systems. The design parameters were optimized by simulation studies for the link system to generate the normal walking motion. The device is connected to a human using elastic components, and therefore, the inertia of the link system is not directly imposed on the user. The human legs are guided to follow the motion of the link system by an assistive force generated by the elastic components.