Analysis For Electric Load Torque Simulator System

As a ground simulation device of loading the moment of force,electric loadsimulator is widely popular with people, because of the advantages,such as smallmoment of force load, low-inertia, high speed and so on. After several years of research,the control strategies and thesuppression methods of surplus torque and other aspectsfor electric load simulator is mature. However, an important issue of electric loadsimulator is not well solved, and this issue is the universality of electric load simulator.Since the design of a electric load simulator is aim at a model of the steering, for thequite different of steering characteristics situation, the designed electric loadsimulatorcan’t perfectly complete the load task, and there is a big problem in accuracyan stability. Therefore, the research of the cause of the universality of load simulator hasgreat practical significance. In this paper, takingthe electric load torque simulationtechnology as background, detailedly analyze the sensitivity of torque loading systemfrom the controlled object of loading side, while give a solution to suppress the positivepeak of sensitivity.Firstly, analyze the background and significance of this subject. Then, from surplustorque, the rotational inertia of the load-side and the steering-side, torsional stiffness,and the control strategies and so on, analyze the research status of electric loadsimulator.Secondly, taking thepermanentmagnetsynchronousmotor(PMSM) as the drivemotor of electric load simulator, according the working mechanism of electric loadsimulator and tested steering, respectively establish the linear mathematical models ofelectric load simulator and the steering. Gives a comprehensive mathematical model,which is taking the torque sensor as a connectinglink.And for the subsequent analysis,appropriately simplify the closed-loop system model.Thirdly, on the basis of precise mathematical model, choose two methods toanalyze the sensitivity, which is about the close-loop system and load-side controlledobject: First,because the system of load simulator is a multivariable system, withconsidering the characteristics of steering, define the sensitivity functionalmatrix, andexamine the gain of the sensitivity functionalmatrix taking advantage of singular valuesof a matrix. Next, on the basis of the sensitivity of a single variable, aiming at the outputresponse of closed-loop system, deduce the sensitivity of double entry system, and then analyze the frequency characteristics of the sensitivity of output response, which isabout load-side controlled object. Based on the two methods, analyze the influence toclosed-loop sensitivity, that is of parameterschange of the rotational inertia of theload-side and the steering-side, andtorsional stiffness.Finally, in order to suppress the positive peak value of sensitivity in the middle andhigh frequency, we compensate the sensitivity function accordingly. And then take thecompensation link to be equivalent to the series link of the controller of the torqueclosed-loop system. At last, the sensitivity function is proved, which is added thecompensation link, through the way of simulation.