Design on Articular Motion & Servo Driving with Experimental Analysis for Lower Limb Exoskeleton Robot

Abstract

According to the characteristics of human lower limb and requirements of joint motion for level walking, the mechanical structures were designed on exoskeleton robot. The simulation on power of joints during requirements of level walking were analyzed and simulated with ADAMS software, and electro-hydraulic driving was designed on exoskeleton joints for locomotion. A PID control method based on joint error estimation was proposed to meet the requirements of joints assistance and flexibility for human lower limb. The locomotion parameters of joints structure are introduced in detail, for which motion range and driving stroke of the exoskeleton robot are optimized. The kinematics of the robot was analyzed and verified by typical actions of the exoskeleton. The mapping of gait and joint driving in the process of exoskeleton walking is divided, and the PID control with error estimation and compensation are given. From the perspective of joint tracking and power, index parameters of two control methods based on joint error estimation and conventional PID are analyzed and compared quantitatively. Finally, experimental results show that the designed joints and driving system of exoskeleton could have a great affection on power assistant for wearer. Compared with common PID control, the discontinuity of joint driving control output interval is suppressed, the joint tracking error is improved and power walking is much more compliant.