Model identification for K mirror turntable of 2 m telescope

A model identification method based on the singular value decomposition and eigensystem realization algorithm(ERA) using Hankel matrix, was proposed for K mirror turntable of 2 m telescope to identify the model's order and parameters. Firstly, the plant was excited using the sweep signal and the position feedback signal was recorded, the test data were analyzed through the power spectrum density function to get the frequency response function of the system. Secondly, the singular value decomposition(SVD) was adopted to identify the Hankel matrix of the system to acquire the order model of the K mirror turntable. Finally, the ERA was adopted to identify the Hankel matrix to acquire the model parameters of the system. The experiment results show that the minimum order of the K mirror turntable is 6, the magnitude phase measurement accuracies of transfer function are 0.31 dB and 0.87 in middle frequency range respectively, compared with the hierarchical identification method, the identification accuracies are improved 50.7% and 23% separately. Results indicate that the proposed method can determinate a balanced and minimal order state-space representation equal to the system's dynamic performance, which is practical and effective in model order determination and parameter estimation.