Study Of Gait Planning Of Quadruped Robot Under Different Ground

Quadruped robot is widely used in irregular terrain for rescue and field operations.As a ground vehicle,it is of great significance to to study the gait planning of quadruped robot on different ground,namely,hard ground and soft ground.This thesis focuses on the problem of the gait planning of the quadruped robot under different grounds,and carries out research on the design of leg mechanisms,kinematics,dynamics,foot ground mechanics,stability analysis,foot drop calculation,and gait planning.(1)The kinematics of leg structure is studied.Based on the existing leg mechanism with switchable degrees of freedom(between single dof and two dof),the forward kinematics and inverse kinematics model of the leg mechanism establishesd by using complex vector method method,aiming at the leg structure with two degrees of freedom and five link mechanism.(2)The problem of the ground mechanics of the legs is studied.Flores model is used as the collision force model of foot end-hard ground,and the mechanical model of foot end hard ground in normal direction is established.The tangent mechanical model of foot end-hard ground is established by using Coulomb friction model of classical friction theory.For soft ground,Bekker bearing model is used to establish normal mechanical model of foot end-soft ground,and Janosi shear model is used to establish tangential mechanical model of foot end-soft ground.According to the different mechanical models of two kinds of ground,the mechanical models of spherical foot end-ground are established respectively.Based on the single leg dynamic model of quadruped robot,the ground mechanical model of quadruped robot leg is established by introducing the foot end ground mechanical model.(3)The gait of quadruped robot is studied and analyzed.The stability of the commonly used walking gait and diagonal trot gait of quadruped robot is analyzed,and the stability margin is solved,and the corresponding stability criteria established in this thesis.Based on the stability criteria of quadruped robot,the feasible regions of landing points of walking gait and diagonal trot gait on hard ground and soft ground are solved respectively.The corresponding foot end trajectory is planned by using the modified cycloid and Bezier curve,and the corresponding gait planning is made.(4)ADAMS and MATLAB are used to simulate and analyze the quadruped robot.The simulation model of the quadruped robot is established to verify the correctness of the calculation of the landing point,the rationality of the foot end trajectory planning and gait planning,and the good stability of the quadruped robot in the process of motion,which can move smoothly on the hard ground and soft ground.(5)The ground walking experiment of quadruped robot prototype is carried out.By collecting the roll angle,pitch angle and yaw angle of the fuselage from the attitude angle sensor,and analyzing the angle change,it is verified that the quadruped robot prototype has good stability and the correctness of gait planning in hard ground and soft ground.