| The elastic torsion system is widely used in the industrial production area. Nowadays, people havehighly requirement for the performance of the equipment and auto control course. And the length oftransmission in the equipment is increased. Due to the elastic characteristic, it exists oscillation whenthe system is operating so that it can reduce the life and the control accuracy of the machine. Evenworse, it may cause accidents in production. According to this, how to minimize the oscillation to keepthe closed-loop system have the satisfied control quality, is the key point for the research of the elastictorsion system.The paper selected the The multi mass elastic torsion system device which designed by B&Rcompany as the research object. After analysis the structural characteristics and operating characteristicsof the research object, some control schemes to control the system should be given in order to make thetarget that the load wheel reach the set speed with the least time and minimum error.The paper built the mathematical model by two methods: mechanism modeling and experimentalmodeling. The method of mechanism modeling is based on the elastic system and combined with motortheory, analysis physics and mathematics, and finally obtain a state space equation model. The builtmodel was simulated with Simulink toolbox in the professional mathematical software MATLAB.Experimental modeling first needs collecting the step response data from the device. The sampling datawas fitted and curves were produced by the Curve fitting tool toolbox in MATLAB in order to get timedomain expressions and work out the transfer function of the system.The paper selected PID control as the control algorithm. Firstly, the principle of PID controlalgorithm was presented. However, though the analysis data, we found the fact that in the real industrialcontrol course, the changes of system parameters can be caused by the change of the load or under theeffect of the environmental factors. On this condition, the controller need change its parameters toregain the satisfied control effect. Therefore, the paper put forward the expert PID algorithm whichcan choose the different control strategies in the different control period though several rules set by theexpert experience. Besides, the paper made the other control method, partial differential PID controller,according to the weakness of the differential item in classic PID control when the system is under the effect of the external interference. By adding a filter in the differential part, the controller can reduce theamplitude by some rules after the beginning of the differential output so that it can be advance control.After the paper introduced these two control schemes, algorithms were edited by Matlab according tothe established system model, and the paper made the simulation control. And the paper made theresearch of the frequency domain of the algorithm by observing the Bode and Nyquist chart in order toanalys is the closed-system s phase margin, amplitude margin and the stability margin to determine thesystem s degree of stability under control.Then the paper applied the two PID controllers to the multiple quality elastic torsion system. Onewas automatically transferred the simulation model in Simulink to C language code in AutomationStudio and downloaded it to the PLC of B&R. The other was by editing C language code in AutomationStudio to realize the closed-loop control.Finally, the paper analyzed the response curve of the two closed-loop systems, calculated the keyelements of the control system stability, overshoot, settling time, steady-state error. Then compared thetwo control algorithm and summarized the advantages and the disadvantages. At last, the paper madesome research on the system robustness to further analyzes the superiority of the control scheme. Theresults showed that the control schemes designed have satisfactory control effect and have the greatpractical application value. |
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