Design And Analysis Of A New Type Of Wheel-legged Quadruped Bionic Robot

At present,with the rapid development of science and technology and world industrialization,especially the continuous improvement of modern automation control level,there are more and more researches on the wheel legged hybrid quadruped robot and the quadruped robot with lumbar joint.The wheel legged hybrid quadruped robot has the advantages of both wheel type and leg type robots It is more flexible in turning and other situations.Therefore,a quadruped robot with more abundant structure is proposed in this paper.The robot not only has a wheel leg mechanism and a waist joint mechanism,but also has a trunk structure which can change the width.It is mainly composed of a waist joint,a trunk and a mechanical leg.The waist joint is a 1U + 2ups parallel mechanism;The trunk part is a frame and a lead screw slider mechanism;The mechanical leg is a series parallel hybrid mechanism,and a walking wheel is installed at the knee joint to realize the wheel foot conversion.The main contents are as follows:The skeleton structure of quadruped mammal is analyzed,and the minimum degree of freedom of quadruped robot is obtained;According to the movement form and characteristics of quadruped mammal,a lumbar joint mechanism is designed based on 1U + 2ups parallel mechanism.A series parallel hybrid wheel leg mechanism is designed based on five bar parallel mechanism,and the degrees of freedom of lumbar joint mechanism and leg mechanism are calculated;In order to improve the adaptability of the quadruped robot in the complex environment,the body structure which can change the width is designed by using the lead screw slider mechanism.Finally,the three-dimensional model of the quadruped robot is established.The kinematics of the lumbar joint mechanism and the leg mechanism are analyzed respectively,the forward and inverse solutions of the leg mechanism and the lumbar mechanism are derived.The velocity Jacobian matrix of the leg parallel mechanism is solved,and the singularity of the leg parallel mechanism is analyzed according to the velocity Jacobian matrix.Based on the analysis of the constraint conditions of the foot end workspace,the Monte Carlo method is used to solve the foot end workspace.The influence of the leg structure size parameters on the foot end workspace is analyzed,and the main parameters affecting the workspace are summarized.Using genetic algorithm,taking the workspace as the optimization index,the main structure size parameters are solved,and the maximum workspace of the foot end is drawn.The static stability of the quadruped robot is analyzed,and the stability margin is used to judge the walking stability of the robot,so as to ensure that it can walk stably;The related definitions of gait planning process is introduced,and a more flexible climbing gait and turning gait combined with the driving of the lumbar joint mechanism of quadruped robot are proposed;The body width adjustment gait and the foot trajectory are planned.The kinematics simulation and analysis of climbing gait,turning gait and body width adjustment gait are carried out by ADAMS software,and the feasibility of gait planning is verified.