Development of a MIMO fuzzy inference system—PI controller for a closed-circuit grinding ball mill circuit

Abstract

This article aims to study the implementation of classical proportional-integrative (PI) controllers and their coupling with the fuzzy inference systems (FISs) in the act of closed-circuit grinding (CCG) ball mill system. The system was formed for a multiple-input multiple-output (MIMO) system, with two inputs, the feed rate (W_F) and speed classifier rotor (V_R), and two outputs, a sieve fraction 45 μm (P₄₅) and the amount of material by a weight inside the drum (hold up [HU]). The model was simulated based on experimental processes and control strategies. The fuzzy-PI controllers were developed on the software, and the data from this process were used to build the database and the necessary knowledge to construct the FIS controllers (with fuzzy rules base 3 × 3 and 5 × 5). Their implementation decreases the error criteria integral of time multiplied by the absolute error (ITAE) and integral of the absolute magnitude of the error (IAE) by 35% and 65%, respectively. Although, applying fuzzy-PI systems with a smaller rule-based outcome gives the benefits of implementing the fuzzy logic (FL) but with a smaller oscillatory performance and a minor negative effect on HU control.