An open loop subspace model identification algorithm for closed loop system

A novel identification algorithm using Q-Markov cover for subspace system operating in closed loop has been proposed. A set of new formulas for reconstruction of the open loop model is derived and the algorithm only needs some linear algebraic knowledge. The unique solution of the open loop subspace model for the general structure of the closed loop is obtained, and the existing conditions for the solution could be used as the identified model criteria index. The algorithm for direct feedback controller and state feedback controller situation is analyzed. Simulation results have shown that the new algorithm is successful.