Fractional order and BICO disturbance observers for a run-of-mine ore milling circuit

Grinding mill circuits are hard to control due to poor plant models, large external disturbances, uncertainties from internal couplings, and process variables that are difficult to measure. 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. Another disturbance observer is introduced in which a Bode ideal cut-off (BICO) filter is used for the Q-filter. A full non-linear plant model is used for evaluation of the performance gained over the ubiquitous PI controller. The simulation results show that the FO-DOB and BICO-DOB schemes are useful additional tools for ROM ore milling circuit control implementations.

► A novel fractional order disturbance observer for a run-of-mine (ROM) ore milling circuit is presented.
► We also present a novel disturbance observer that uses a Bode ideal cut-off filter.
► We use a full non-linear plant model for the ROM circuit to evaluate the performance gained over the ubiquitous PI controller.
► Disturbance observers provide an additional degree of freedom in tuning for set-point tracking and disturbance rejection.
► Novel disturbance observer schemes are useful additional tools for ROM ore milling circuit control implementations.