A structure of two-degree-of-freedom Internal Model Control from feedback/feedforward scheme

Internal Model Control (IMC) yields very good performance for set point tracking, but gives sluggish response for disturbance rejection problem. Feedback/feedforward controller has been widely used to overcome the disturbance rejection. However, feedback/feedforward IMC is suffering with the difficulty of measuring disturbance and/or making disturbance model in real plant due to the possibility of more than one disturbance. The present study has developed a controller for disturbance rejection based on feedback/feedforward IMC structure. The controller could give a good performance without model disturbance. The results show that the proposed method is better to the existing two-degree-of-freedom IMC (2DOF IMC) controller in the presence of model mismatch.