一种基于继电反馈的预测模型闭环辨识方法

针对模型预测控制中过程模型的辨识问题，提出了一种基于继电反馈的预测模型闭环辨识方法.采用非对称继电器与包含PID控制器和被控过程组成的广义过程构成闭环反馈系统，继电器的输出作为PID控制器的设定值.利用非对称继电器激励下产生稳定的不对称振荡响应，直接获取Nyquist曲线上的两个频点，基于快速离散傅里叶变换的辨识算法可辨识该广义过程的一阶加纯滞后（FOPDT）模型.与开环阶跃测试方法相比，可降低测试对被控过程的扰动幅度，仅需要进行一次继电器激励测试即可获得广义过程的模型.

Relay feedback based closed-loop predictive model identification method

A relay feedback based closed-loop identification method was proposed for identifying the general process model in model predictive control.In the relay feedback system,the asymmetric relay is used as the feedback controller for the general process which includes the proportional derivative controller(PID) controller and the controlled process,and its output is the set point of PID controller.Two frequencies in the Nyquist curve can be calculated directly from the system's asymmetrical oscillation response due to the bias relay.The first order plus dead time(FOPDT) transfer function model of the general process can be obtained through the proposed identification method based on fast discrete Fourier transform(FDFT) algorithm.Comparing to the traditional step test,the presented closed-loop test method decreased the disturbance to the controlled process and identified the general process model identified by only one relay test.