Improving the Multivariable Control of the OreGrinding System using Disturbance Observer Mechanism and the PI Controller

Ore grinding system is a multivariable mechanism which is used in mining industry, metallurgy, cement production, chemicals, pharmaceuticals, ceramics and various research laboratories. Previous control methods of this system include open multi-loop PID controller, Model Predictive Control (MPC), adaptive control and robust control. The mentioned techniques do not show proper performance, when exposed to intense disturbances. In this research, an iron ore grinding system with intensive internal and external disturbances has been considered. Here, we have used a multivariable control method based on disturbance observer with two inputs and two outputs in the leading loop, and a PI controller for tracking the reference input in the closed loop. This method includes a controller for the product size loopand a controller for circulating load loop. In contrast to traditional disturbance observer systems which are more suitable for minimum phase systems, here the disturbance observer is improved to be used to estimatethe disturbance in a non-minimum phase system as well. To show the efficiency of the proposed control method, the iron ore grinding system circuit has been simulated in the Simulink environment and the designed controller has also been applied to it. The simulation results prove the proper performance of the suggested technique in the presence of various external disturbances in different practical situations.