ADRC Combined with IMC for Non-Minimum Phase Systems

The integrated control method, active disturbance rejection control (ADRC) combined with internal model control (IMC), is proposed for non-minimum phase systems. The ADRC combined with IMC is to reduce the influence of zeros on right half plant (RHP), system uncertainty and outer disturbance. An improved IMC is put in the inner loop and ADRC is adopted in the outer loop. In order to enhance the system's stability, an approximate zero phase error model of controlled plant (ZPEM) is used as the internal model in the IMC control loop where the feedback of the inner loop is the dynamic weighted filter sum of the real output and the ZPEM output. The theoretical analysis and simulations verify effectiveness of the proposed method for non-minimum phase systems.