| Through the loading system,the research of mechanical equipment or system about coupling relationship between various information characteristics and faults and load identification methods under different types of loads can been studied.And,by simulating the actual load in the case,the test data is used for performance analysis and product development of mechanical equipment.Magnetic powder brake loading is a kind of loading test systems,because of its constant torque characteristic,linear relationship between output torque and excitation current and higher controllability,magnetic powder brake loading has been widely used in all walk of life.With the improvement of loading precision and loading quality,it is very important to analyze and control the magnetic powder brake.Based on the analysis of working principle of magnetic powder brake,the mathematical model is established by using the method of mechanism analysis.And the influence of structural parameters and magnetic parameters on the loading performance is analyzed in detail.The analysis shows that the effects of various parameters can not be used to express a certain relationship,and there are interaction constraints between the parameters.In order to improve the loading performance of the magnetic powder brake,can be studied from the perspective of the corresponding control algorithm design.In view of magnetic powder brake control object,the conventional PID control,Smith predictor control,fuzzy Smith predictor control and fuzzy integral Smith predictor control are designed.From the two aspects of the rapidity and stability of the control system response of the designed control algorithm are compared,show that:Smith predictor control is superior to conventional PID control.The system overshoot is reduced by 9.9%.The rise time is shortened by 0.5s.But the precision of mathematical model required highly to these two kinds of control algorithms.The applicability is reduced for magnetic powder brake.That the precise mathematical model can not get solved by the fuzzy control,but the control residual formed by fuzzy Smith predictor control,the control system can not up to the steady-state value.The rise time of integral parallel fuzzy Smith predictor control system is 0.9s,improve the rapid response,but also cause the overshoot is 13.45%.The overshoot of integral series fuzzy Smith predictor control is 0.9%,and the speed is also ideal,rise time of 1.9s,is an ideal control mode.Based on the working principle of PLC and Smith predictor controller,fuzzy controller and integral controller operation mode,this paper presents the realization method of each controller.The program design flow chart of PLC is given for fuzzy integral Smith predictor control.The fuzzy control query table by off-line computation,online assignment method.Smith predictor control is realized by updating the output data of memory unit,and the realization of integral controller similar Smith predictor controller.The relationship between output torque and excitation current and magnetic powder brake's stable slip torque characteristic are verified by magnetic powder brake loading test.At the same time,two polynomial fitting equation of input and output are given to guide loading from the angle of test.That magnetic powder brake is a typical inertial system with pure delay is proved by its response to step input.The correctness and effectiveness of the control algorithm are verified by the comparison between the response curve of the triangular wave signal and the sine wave signal and the simulation results of the control algorithm. |
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