Kinematics Study Of Quadruped Robot Based On Double Closed-chain Walking Leg Mechanism

The performance of the legged robot is mainly determined by its leg mechanism.The leg mechanism of the existing multi-legged robot is mostly open-chain joint structure,and the advantages of the closed-chain leg mechanism have not been deeply explored.A new type of double-closed chain walking leg mechanism is proposed: the crank-rocking mechanism is used as the main closed-chain to provide the swinging characteristics of the leg mechanism in accordance with the animal walking;the crank slider mechanism is used as the auxiliary closed-chain.It plays a role in adjusting the length of the leg and increases the flexibility of the mechanism.Based on the leg mechanism,a four-legged robot is constructed,and the foot trajectory of the robot movement is planned.The geometrical analysis method and D-H method are used to model the kinematics of the leg mechanism.By comparing the advantages and disadvantages of the two methods,the precautions of the D-H method in the modeling process of the closed-chain mechanism are listed.The velocity and acceleration equations of the robot leg mechanism are derived by using the established kinematics model.The inverse kinematics equation is derived by the model.For the established mathematical model and the planned foot trajectory,the optimization tool is used to optimize the size of the leg mechanism,and the virtual prototype model of the leg mechanism is established by using the optimization result,and the kinematic formula is carried out verification.The robot must be able to maintain stability and have the athletic ability.The stability of the quadruped robot is analyzed,and the conditions for the robot to maintain static and dynamic stability are given.In the static and steady state,the robot is planned for crawling gait,and the timing of the robot's crawling legs is given.Under the dynamic steady state,the robot is planned for the trot state,and the diagonal trotting pendulum is given.Gait planning lays the foundation for virtual prototype simulation of robots.After the virtual prototype modeling and related parameters are set for the robot,the simulated crawling gait and diagonal gait state are simulated respectively.Data analysis is performed on the obtained simulation results,and the analysis results of the two parts of the body and the foot are given.In the crawling gait,the robot can walk slowly and keep the body stable;in the diagonal gait,the robot can walk at medium speed and keep the body stable.