Static stable gait planning based on center of gravity stability constraint for lower limb exoskeleton walking aid robot
LI Juan, CAI Xiao wei, LI Wei da, ZHANG Xiao, ZHU Qi huan
(School of Mechanical and Electric Engineering, Soochow University, Suzhou 215021, China)

Abstract: In order to solve the problem of large error between the actual and objective COG(center of gravity) trajectory,which caused by using only a few parameters to determine the key positions of the robot and then interpolating the key positions, a gait planning method of the lower limb exoskeleton robot was investigated. The genetic algorithm was used to solve the joints position directly based on the COG in this method.The kinematics model of the robot using D H method was established, and the relationship between the COG and the joints position was obtained. The COG trajectory of the robot was planned based on the maximum stability margin. Under geometric constraint, joints position was obtained using the genetic algorithm and each joint angle was calculated according to the inverse kinematics model. The method made the actual and objective COG trajectories be highly consistent. Finally, the robot walking experiment was carried out to verify the reasonableness of the method. The experimental result shows the feasibility and effectiveness of the proposed method.

Key words: lower limb exoskeleton; gait planning; center of gravity; genetic algorithm