Control Performance Evaluation Based On Subspace Identification And Frequency Domain Characteristics

Industrial production is rapidly transitioning from electronic to digital and intelligent.During this period,the amount of obtained operation data and storage greatly increased,people can quickly calculate and analyze the circuit performance of the device based on historical data.As a result,the new focus has shifted to how to use the data reasonably,how to calculate and analyze the relevant performance of the loop to confirm whether the system is operating as expected,and whether the controller performance is stable and how to improve and re-target the poor performance loop.The subspace identification method has the characteristics that the system state space model can be obtained directly from the input and output data without identifying the complete object model.It can be used for industrial production process control performance evaluation by simplified calculation steps and reduce complex calculation errors.Based on subspace identification,this paper studies the problem of loop performance evaluation from the perspective of frequency domain.The content mainly includes the following points:1.Review the subspace identification method,briefly describe the mathematical tools of orthogonal projection and skew projection used,and the process of calculating the orthogonal projection using QR decomposition,and introduce the basic process of subspace identification.2.In actual production,the data collected from the field inevitably contains noise,and the data is often lost due to equipment or communication reasons,affecting the use of subsequent analysis.The method of wavelet threshold denoising is used to process the noise in the data collected in the industrial field and weaken its influence in the process of subspace identification.Comparing the experimental results before and after the preprocessing of the collected field data,it is proved that the wavelet threshold denoising method combined with the data preprocessing can improve the identification accuracy.3.On the basis of subspace and data processing,combining with frequency-domain characteristic analysis and synthesizing frequency-domain related indexes,specific heuristic rules are proposed,and the performance evaluation results of mature software are compared to prove the feasibility of the proposed heuristic rules.The proposed method provides a new reference direction for system performance evaluation.