Fractional order disturbance observer for a run-of-mine ore milling circuit

Grinding mill circuits are hard to control with high performance due to poor modeling, large external disturbances, and uncertainties from internal couplings. This paper proposes a novel fractional order disturbance observer (FO-DOB) for a run-of-mine (ROM) ore milling circuit. A fractional order low pass filter (Q-filer) is used in the DOB to offer an additional degree of freedom in tuning for set-point tracking performance and disturbance rejection performance. A 3×3 linear time invariant MIMO plant model is used for evaluation of the performance gained over other commonly used controllers such as PID and MPC. The simulation results show that the FO-DOB scheme offers promising potential in real world ROM milling circuit implementations.