Design Method And Analysis Of A Guiding Mechanism For Determining Trajectory

A new design method of guiding mechanism is proposed to precisely realize the expected trajectory.The mechanism is an asymmetrical parallel mechanism with two branch chain.One side of the chain is a serial mechanism,which provides force support for the mechanism;The other side of the chain is a five-bar mechanism with the moving pair,and the displacement compensation is realized through the reciprocating motion of the moving pair,so as to achieve the precise trajectory.The whole mechanism is a redundant parallel mechanism,and the guide chain can carry out the motion with the support chain at the same time.Through the coordinated movement of two branches,the force and speed of the terminal operator in the process of motion are always consistent.This design not only overcomes the shortcoming of the precision limitation of the series mechanism,but also can realize the precise guidance of the trajectory through the five-bar mechanism.In order to achieve the expected purpose of the mechanism,firstly,the design criteria of the mechanism are determined.Based on the design criteria,a series of guiding mechanisms are synthesized based on the spiral theory and the corresponding 3D diagrams are drawn,and one of the mechanisms is selected for analysis according to the application.Secondly,according to the type of selected guiding mechanism,the kinematics and performance analysis were carried out.The forward and inverse kinematics of the mechanism was calculated,the working space was solved and the speed Jacobian matrix was calculated.Based on the jacobian matrix,the static stiffness and dexterity of the mechanism are analyzed and compared with that of the series mechanism to verify the superiority of the mechanism performance.The error analysis of the mechanism is carried out.The simulation and trajectory planning of the virtual prototyping mechanism are studied.The 3D model of the mechanism is imported into ADAMS to carry on the motion simulation analysis.The simulation results are compared with the theoretical calculation results to verify the correctness of the mechanism motion.Then the influence of the length error,drive and assembly error on the output position of the mechanism is considered respectively.Finally,the dimension of the mechanism is optimized according to the specific task of the organization to realize the high-speed bogie U-shaped groove,and the regulation of the compensation displacement in the guide module is calculated,and the regulation of the speed and acceleration of each driving joint of the mechanism are obtained.The results of the optimization using Simulink/SimMechanics for simulation experiments,adding interference factors,through the PID control,making the end of the agency operator output error to a minimum.