第七章基于继电测试的参数辨识.pptVIP

FUNDAMENTALS OF RELAY FEEDBACK Generating Sustained Oscillation For many systems there will then be an oscillation where the control signal is a square wave and the process output is close to a sinusoid. Relay feedback system Process input and output in the relay test Nyquist Plot and Describing Function Approximate Transfer Functions Simple Approach Once the model is selected, we can back-calculate the model parameters from two equations of the ultimate gain and ultimate frequency. Fourier Transform Method Improved Relay Test Asymmetrical Relay Feedback Relay With Hysteresis Realizing Hysteresis by a delay Assymetrical Relay With Hesteresis Unconventional Relay Methods Relay Feedback with a Integrator Two Relay Tests Relay Plus Step * * Chapter 7 Parameter Identification from Relay Test Li Shaoyuan E-mail: syli@sjtu.edu.cn Process Output Relay Output (u) (y) h a Block diagram for the asymmetric relay feedback system Process connected to relay with hysteresis The relay with delay For the first order plus dead-time model The biased relay Oscillatory waveforms Modified relay feedback system Process ? ? + u y - r Process input and output in the modified relay test Output Input Time Time following structure is considered: Making and we have Block Diagram of Two Relay Test Output Input Time Time Process input and output in the two relay test The iteration equation is given by Process input and output in a relay + step test