Subspace identification of countercurrent rare earth extraction process based on nonlinear state-space models

The subspace identification problem of rare earth extraction process, which is based on nonlinear state-space models, is considered in this paper. The nonlinear part of the system model is approximated by the radial basis functions. The parameters are estimated in two steps. Firstly, The system matrices are determined by subspace identification method. Secondly, the parameters of the radial basis functions are computed by optimization of output error cost function. Real industrial experiment of rare earth extraction process is implemented and the results show the efficiency of the proposed method.