Research On Vibration And Control Of Stewart Platform For Engineering Vehicle Driving

Aiming at the research and development needs of cabs for large-tonnage loaders and double-wheel roller,this paper takes 6-UPU Stewart platform as the research object.By simulating the driving conditions of engineering vehicles under different typical road conditions and working conditions,in order to verify the comfort of human-machine operation in the product development and trial-manufacture stage and shorten the research and development cycle of cabs,it provides a research platform for the research and development of main engineering vehicle cabs.Based on this background,this paper studies the vibration analysis,kinematics control and related experiments of the platform.The main research contents are as follows:Firstly,kinematics verification of the motion simulation Stewart platform is carried out,and the inverse solution,velocity and acceleration model of the platform is established.On this basis,the workspace,velocity and acceleration of the platform can meet the requirements of the motion simulation driving design.Through the branching stiffness model,the stiffness matrix of the platform is obtained,which lays the foundation for the subsequent vibration research.Secondly,the vibration model of the motion simulation Stewart platform is established.Firstly,the dynamic model of the motion simulation Stewart platform is established based on the virtual work principle,considering the stiffness of each joint,the influence of the bar and the load of the moving platform.Considering the actual working conditions,the dynamic model is simplified and the vibration model of the platform is obtained.Then,the vibration model of the platform is solved by the aid of MATLAB software.Motion simulation of Stewart platform in the workspace of different natural frequencies and platform free vibration response and forced vibration response.Thirdly,because of the limited motion range of the motion simulation Stewart platform,it can not completely simulate the motion state of the engineering vehicle,so we need to rely on the washout filter algorithm to convert its real motion into the analog signal that makes the operator feel similar.This paper chooses the classical washout filtering algorithm as the main algorithm for platform control,designs and determines the parameters of the proportional link,coordinate change link,high-pass acceleration channel,high-pass angular velocity channel and low-pass acceleration channel of the washout filtering algorithm,and verifies the accuracy of the algorithm by comparing the simulation with the actual data collected.The platform motion has real-time,accuracy,rapidity and stability.An AC synchronous servo system is built and verified by the joint simulation of Adams and Simulink.Finally,the motion control system of the platform is built based on the Beifu controller and the Beifu servo system.The control model with the washout filter algorithm is converted into ST language and written into the Beifu controller.The kinematics information of the engineering vehicle in the virtual scene is collected,and the motion attitude of the motion simulation Stewart platform and the attitude measured by the sensor are solved by Simulink software.Through comparative analysis,the control system is validated.In order to verify the correctness of the dynamic model and vibration model of the platform,the natural frequency experiment is carried out by using the knock method.