Design and Evaluation a New Type of Semi-active Lower Limb with Knee Joint Booster

This article presents a new lower limb orthosis for helping weak knees during human locomotion. The orthosis structure has 10 degrees of freedom. It utilizes a series elastic actuator, equipped with an elastic rope that transfers torque generated by the motor to the orthosis link. The performance of the proposed lower limb orthosis is virtually simulated by using ADAMS-MATLAB Co-simulation software. The orthosis is designed based on the anthropometric data of a normal human body with a mass of 76 kg and a height of 180 cm. The simulation scenario involves walking with an average speed of 1 m/s on a straight path, and the knee orthosis can bear 40% of the torque exerted by the knee joint during the gait cycle. The simulation aims to evaluate the effectiveness and efficiency of the orthosis in assisting the weak knee joint. The simulation results indicate that The orthosis reduced the knee joint torque by more than 13 Nm in a healthy person, which indicates lower forces on the weak knee. Moreover, the orthosis decreases the maximum energy needed per gait cycle, which implies a higher efficiency and reduces the metabolic cost of the body in the gait cycle.