Research On Control For A Humanoid Walking Aid Device Under Different Ground Conditions

The walking aid, as a branch of the humanoid robot technology, involving ergonomics, robotics, mechatronics, computing science and so on, is a worldwide hotspot nowadays. A powered walking aid is a kind of man-machine integrated machinery that provides walking power for the patients who suffer from lower limb paralysis. And due to the specificity of patients, higher requirements are demanded for the control system's performance, comparing with control systems of general machineries.After the analyze of the control theory of the lower limb walking aid, the corresponding lower limb humanoid robot is studied in this essay in order to get related conclusions and apply the conclusions back to the study of the lower limb walking aid. The background of the essay is firstly introduced and the progress of the research on humanoid robots home and abroad is discussed. Some basic concept is introduced in terms of the structure of humanoid robots as well as several criteria for analyzing humanoid robots' stability at present, among which the ZMP(zero moment point) is most commonly used.A 7-linkage and 7-mass model of the lower limb humanoid robot is built. By the way of building a coordinate for each joint and derivation of the coordinate-conversion formulas, linkages and joints are connected as a whole so that research and analyze can be easily done. On this basis, the dynamic and kinematic analyze is conducted and the model is built.A 3D-model of the lower limb humanoid robot is also built using Solidworks, and gait planning of the robot under different ground conditions is conducted with the 3D-model containing plane ground and up/downstairs. Walking on plane ground is quite easy for the robot while walking up/downstairs is complex which is one of the difficulties of this essay. By analyzing the angle track of each joint and calculating the motion track of each joint using the inverse kinematics, constraint equations are derived. Then the walking of the lower limb humanoid robot can be constrained, performing both stably and in the posture of a real human, by applying the constraint equations to the model of the robot.