Conceptual design of a lower limb motion assist robot with bodyweight support

In this paper, the concept of a new walking assist robot is proposed for helping elderlies and overweight people, as well as healthy users. Walking assistance in this robot is realized through weight support and reduction of user's Foot Reaction Force (FRF). The proposed robot has six degrees of freedom per leg that imposes no limits on human's natural gait. It has only two active joints that are prismatic and all other joints are passive. This results in reduction of power consumption for the robot. Consequently, this robot will require smaller power supplies. The special architecture of the designed robot permits its accommodation to users with different sizes and heights. Reduction of user's FRF is accomplished by applying a support force to the groin via the seat. The mechanism of robot is designed in the way that the applied support force is in the same direction of user's FRF. The validity of this matter is also discussed through the force analysis and simulation of the mechanism.