# Optimal Cascade Controller Tuning Method Applied to the Density Control Loop of a Regrinding Process

**Autor(es):**Torga, Diego; Reis, Lucas; Euzébio,Thiago

**Resumo:**(EN) The objective of this paper is to develop an optimal tuning method to calculate the parameters of the two proportional, integral and derivative controllers (PID) of the cascade system, in a single procedure. This method is formulated as an optimization problem involving a cost function and three constraints. The cost function aims to minimize the integral absolute error (IAE) of system output when a disturbance is applied. The robustness and stability of the closed-loop system are ensured by the restrictions applied to the maximum of the sensitivity function. Therefore, in the presence of disturbances, a fast response is guaranteed. This method is applied in an iron ore pulp density control problem in a simulated regrinding process. The secondary loop acts on the sump box water rate control in the mill discharge through a valve, and the primary loop acts on the sump box discharge density control. A good performance of this loop results in a better classification of the particles in the cyclones after the regrinding, which in turn directly affects the subsequent concentration steps. Moreover, this control impacts in the mill performance, because the circulating load solids percentage is an important variable in this process. In the simulation are inserted some disturbances that can occur in practice, such as variation in particle size and solids percent in the circuit feed and in the water flow that feeds the sump box for pulp dilution. The results obtained show the effectiveness of the proposed method in the ability to minimize the disturbance effect on the system output.

**Periódico:**International Congress on Automation in Mining - Automining 2018

**Ano:**2018

**Volume:**6

**Páginas:**p. 1-10

**Disponível em:**https://www.researchgate.net/publication/337403071_Optimal_Cascade_Controller_Tuning_Method_Applied_to_the_Density_Control_Loop_of_a_Regrinding_Process