Identification of fast sampled model for multi-rate sampled systems

Multi-rate sampled systems are very common in the chemical process industry. To improve the performance of multi-rate systems, the fast sampled transfer function of the multi-rate system is often required. In this paper, the multi-rate system is converted to a single rate system with multi-inputs and single-output using lifting technique. Then the method to transform the transfer function model of single rate lifted system into diagonal standard realization is introduced. Finally, the transfer function model of the fast sampled system can be easily obtained from the diagonal realization according to the relation between the state space model of lifted system and that of fast sample rate system. The simulation results show that the method proposed in this paper is effective.