Implementation of Pneumatic Air Muscle for Actuating Knee Exoskeleton Using Four-Bar Linkage

Abstract

The knee exoskeleton is a device that assists users with weak knees to walk. It consists of a mechanical construction put around the human knee which is equipped with an actuator for movement. One mechanism that can be used to mimic movement of the real knee is the four-bar linkage. This research explores the possibility of using pneumatic air muscles as actuators for a knee exoskeleton with four-bar linkage implementation. A pneumatic air muscle is a single-acting linear actuator that contracts when filled with pressurized air, mimicking muscle contraction. It is much lighter than electrical motors, but—according to characterization done in this research—is difficult to control due to its inconsistent torque output. Nevertheless, this research shows that simple gait movements can be simulated using a knee exoskeleton actuated by pneumatic air muscles with an on-off control scheme.