Hu Huaizhong,Sun Lianming,Liu Wenjiang
(School of Electronics and Information Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract:A new identification method for a linear discrete-time noisy closed-loop system was proposed based on the output over-sampling technique.According to the relat-onship between the selection of over-sampling rate and the estimation accuracy,the calculation method of optimal over-sampling rate was obtained.When the system output was over-sampled,the original system model will be changed to a new over-sampled model.For the output with white noise and colored noise,a general least squares method and prediction error method are applied respectively to identify the overª²sampled model.By the connection of the over-sampled model and the original model,the original close-loop model can be recognized.The distribution of the estimation accuracy under different over-sampling rate was studied and the calculation method of the optimal over-sampling rate was proposed.Compared with conventional algorithms,the method is easy to be realized,with less operating load and high estimation accuracy.Numerical simulation shows that the estimation accuracy is 98£¥ when the signal-to-noise ratio is bigger than 15 dB and the optimal estimation accuracy is obtained while the over-sampling rate is between 15 and 20£®
Keywords:system identification;close-loop;over-sampling;estimation accuracy; over-sampling rate