| The quadruped robots have strong adaptability,and their complex terrain passing ability is better than wheeled and tracked robots.Therefore,they are widely used in industrial,military,aerospace and other fields.In order to improve the motion flexibility and environmental adaptability,this thesis designs a quadruped robot with parallel spine based on existing domestic and foreign researches.The waist parallel mechanism adopts3-RPS(R : spherical pair P : moving pair S : rotating pair).According to its structure and motion characteristics,the kinematics and dynamics models are established.The motion stability of rigid spine and parallel spine robot under trot gait is compared,and the common control strategies for parallel spine are proposed.Since the quadruped mammalian body has better flexibility and stability,this thesis constructs the basic structural framework of the quadruped robot from the perspective of bionics,and optimizes the size of the parallel mechanism.According to the influence coefficient method,the kinematics analysis of the 3-RPS parallel mechanism is carried out,and the position,velocity and acceleration of the parallel mechanism are obtained.The numerical calculation is carried out by MATLAB,and the inverse solution of the mechanism position is obtained.The kinematics simulation of the mechanism is carried out by ADAMS.The comparison of the two groups of results shows that the motion law of the waist parallel mechanism is in good agreement with the cat spine.In order to better analyze the dynamic characteristics and optimize the control of the parallel mechanism,the dynamic model of the waist parallel mechanism is established based on the Lagrange method.The driving force of each driving branch and the angle change of the moving platform are obtained by numerical calculation.The dynamic simulation of the parallel mechanism is carried out by ADAMS,and the results obtained are mutually verified with the numerical simulation results.The results show that the design of the dynamic model of the parallel mechanism and the simulation results conform to the theoretical calculation.Reasonable structure and gait determine the stability of robot motion.According to the stability criterion and gait coordination,the optimal gait of the robot is determined.Then the gait simulation of the robot with rigid waist and parallel waist is carried out.The simulation results show that the motion stability,foot force and yaw of the parallel spine robot are better than those of the rigid spine robot,which further verifies that the parallel spine robot has good motion stability.In order to meet the demand of parallel spine for motion control accuracy,a simulation model of parallel spine motion control system is established based on fuzzy PID controller.The simulation results show that compared with the traditional PID controller,the dynamic response characteristics and position tracking accuracy of the parallel mechanism drive control system are greatly improved by the fuzzy PID controller,which can meet the requirements of the parallel mechanism drive part for the rapidity and tracking accuracy of its control system.Through the design of the control system,the yaw error of the robot during walking is further eliminated,and the rationality and superiority of the control scheme are verified. |
