Input load disturbance rejection of non-minimum phase processes using Disturbance Observer Control Scheme

This article proposes a systematic disturbance observer (DOB) control scheme for open-loop non-minimum phase (NMP) plants with time delay. A novel optimal analytical result of the input disturbance rejection criterion is derived and optimal analytical solutions of both the set-point tracking controller and the DOB are provided in terms of H2 norm performance specification. Both the set-point tracking performance specification and input load disturbance specification can be quantitatively achieved by conveniently tuning the adjustable parameters. The typical first order NMP process with time delay is analyzed based on the proposed control structure, and a simulation example is given. The simulation results verify that the proposed scheme can eliminate the influence of input load disturbance and the ISE specification can be quantitatively tuned.