Experimentation research on Lower-limb Power Assisted Robot

The Lower-limb Power Assisted Robot is a typical exoskeleton power assistance device, which is worn on the user's lower extremities. It can help the elderly and the infirm walk independently. According to the characteristics of human lower extremity joints, a robot with four-bar knee joint whose pelvis and knee joint are driven by the motor-driven screw-nut body is designed. Employing the Denanit-Hartenberg (D-H) method, the robot kinematics is analyzed, the equation of which was established. Based upon the law of human gait, the robot's trajectory planning is accomplished. According to the dSPACE system, the hardware-in-the-loop experiment system of the single leg is established; the step experiment, sine response and walking test with load are accomplished. Experimental results show that the robot can achieve the gait law and has strong load capacity.

I. Introduction

The Lower Power Assisted Robot is a typical exoskeleton power assistance device, which is worn on the user's lower extremitie s, and by imitating the structural characteristics and the walking behaviours of the human lower limbs, it plays the role of supporting, protecting and assisting in the user's walk. Due to the substantial increase in the number of patients suffering from lower limbs movement disorder for various reasons, their needs for rehabilitation are growing, so the wearable robot has very bright market prospect. The 1980's is the initial stage of studying the wearable power assistance walking legs, and the study entered into a stage of comprehensive development after l990. The Berkeley Robotics and Human Engineering Laboratory in the University of California developed the “Berkeley lower extremity exoskeleton” (Berkeley lower extremity exoskeleton, BLEEX)[1] for the U.S. military, which consists of the backpack- style outside the frame, the metal legs and the corresponding hydraulic drive device. The mechanical system adopts the similar structure to human body, so that soldiers wearing it can increase endurance. Developed at the University of Tsukuba in Japan, HAL (Hbyrid Assistive Limb)2–3, is put to use to help patients suffering from gait disorder. The study on wearable robot in China is still in the laboratory research stage. For example, a robot which can help lower limbs cohering with the human body movement and provide the impetus is designed 4–5 in the Hefei Institute of Intelligent Machines of the Chinese Academy of Sciences. This thesis mainly focuses on the mechanical design, control and simulation, and experimental study of the wearable robot. Through a great number of theoretical research and experimental studies, it provides the theoretical foundation and experimental platform for further study in the future.