Research On Gait Planning For A Hydraulic Quadruped Robot

More than half the Earth’s landmass is rugged mountainous, hilly, forest and othercomplex terrain, where is inaccessible to the wheeled and tracked robot. But quadrupedbionic robot, which has the characteristics of four-legged mammals’ kinematic flexibility,can be able to adapt to the complex terrain, and quadruped bionic robot can completemilitary material transport, disaster rescue, field exploration tasks in complex terrain. Gaitplanning is one of the important research fields of robot and the basis of quadruped bionicrobot walking stably on complex terrain, and it is significance for robot to adapt to complexterrain, to improve stability, to reduce energy consumption and improve dynamicperformance.Based on the hydraulic quadruped robot platform designed by our laboratory, this paperfocuses on the research of gait planning based on robot model.Firstly, the kinematic model of robot is established by the D-H parameter method. Forthe solution of inverse kinematics of redundant robot, an extended Jacobian matrix methodbased on performance optimization function is proposed, which can get the analyticsolution of redundant robot. This method is verified by comparing with the gradientprojection method through simulation. In order to reduce the impact force of the robot footduring landing, an algorithm of planning of foot trajectory based on composite cycloid isstudied, and this method can avoid the jerking movement and reduce the impact force. Forthe robot to achieve the uniform motion, a uniform speed of foot trajectory method basedon polynomial and linear combination is proposed. Finally the effectiveness of the twomethods is verified by simulation.In the study of static gait planning, this paper presents a straight walk gait planningmethod, with low energy consumption, and it is suitable for planar motion. For improvingthe stability margin, a Zigzag walk gait planning method based on the incentre ofsuboptimal triangle which in the stability region is studied. The robot can move its body bythis method to obtain larger stability, and with this method the robot can move stability incomplex terrains like slope. Finally the effectiveness of the two methods is verified by thejoint simulation of MATLAB and ADAMS.In the research of dynamic gait planning, it is realized that the quadruped robot can movestability on flat terrain in trot gait with the foot trajectory planning method, firstly. And anew algorithm based on the adjusting angle of the robot foot end is proposed for thestability of quadruped robot walking on a slope, which can improve the stability of the robot. Then the lateral diagonal gait of the robot is studied, the lateral stability of robot isanalyzed and then it is verified by simulation. In order to solve the problem of gait planningwhen the quadruped robot is subjected to lateral impact, a lateral gait adjustment methodbased on the foot end position correction is proposed. Finally, the validity of the algorithmproposed in this paper is verified by joint simulation of MATLAB and ADAMS.Finally both the static walk gait and the dynamic trot gait are experimented by actualhydraulic quadruped robot, and the effectiveness and practicability of the proposed gaitplanning methods are verified by the experimental results.