| Servo-loading system,as one of the most important devices in the semi-physical test,can greatly save resources,shorten the cycle time of the project and improve the efficiency during the researching process,which would promote the development engineering research enormously.According to its difference of the actuator,it can be divided into mechanical loading mode,electro-hydraulic loading mode and electric loading mode.The electric loading mode,as the latest loading mode for the research,has its own obvious advantages compared with traditional loading mode.Therefore,taken the linear motion mechanism as the research object,this paper tries to design an electric servo loading system and analyze its loading performance.At the same time,the electric servo loading system will be also used to simulate the load of the rectilinear motion mechanism under the working condition.Apart from the actuation of the measured linear motion mechanism,it will also be completed while driving the measured linear motion mechanism,which is designed to testify its working performance and its reliability.First of all,based on the technical requirements of servo loading system,the overall scheme will be designed in the thesis.In order to achieve linear motion,the method of rotating motor in coordination with motion conversion mechanism is also discussed in the paper.Hence,the passage will have a detailed description to it's composition and principle of the system.Based on this,the specific structure of the system loading part and the driving part will be designed and drawn.Taking the diversity of research into account,this paper will select the ball screw and steel belt drive mechanism as the motion conversion mechanism,the main mechanism and components in the system.Secondly,the servo loading system is modeled as the loading unit,the load unit and thedriving unit in the paper.In the first place,according to the principle of coordinate transformation and vector control of permanent magnet synchronous motor,the mathematical model will be established,trying to analyze the composition and mechanical model of the loading unit and the drive unit.At the same time,combined with the mathematical model of permanent magnet synchronous motor(PMSM),the mathematical models of the two would be set up respectively and their mathematical models will be built with the application of MATLAB/Simulink software.Furthermore,the Solidworks software will be used to draw the3 D model of the load cell.Then we will give a detailed explanation to its preprocess,add constraints and loads respectively by the importion of ADAMS/View software.Then,after the input and output state variables are determined by the dynamic model,the control parameters will be exported to the MATLAB/Simulink software through the ADAMS/Controls interface,so that the co simulation model of the servo loading system will be completed.Finally,after the simulation parameters of the servo loading system is determined and the joint simulation model is replaced,and the undisturbed characteristics of the loading part and the driving part will be analyzed respectively.The analysis is proposed through the PID feedback control,and the parameter tuning of the PID control model is carried out to analyze the non-disturbance characteristics.The results show that the loading force of the loading part is relatively stable,and due to the lag time of the belt drive,the driving line speed fluctuates during the start-up phase of the drive section.The problem that caused the this kind of fluctuation can be sloved by the designed by the application of the appropriate starting curve.This problem needs to be further studied.In my thesis,the paper puts its emphasis on its steady state after 0.2s.According to the technical requirements of the servo loading system,it points that if the loading part and the driving part run together,and the interference will be generated during the process.Therefore,a feed forward compensation control based on structural in-variance principle will be introduced to suppress the interference.Through the simulation analysis of the system with feed-forward compensation control,the interference suppression rate could be reached to more than 90%.The simulation analysis will be carried out to verify that the method is effective to improve the loading performance.Make the servoloading system meet the technical requirements and this design scheme is feasible. |
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