Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Design of RST digital controller and PLC implementation on a Water Level Bench
Submission Author:
Marco Antonio dos Santos Caballero , AM
Co-Authors:
Marco Antonio dos Santos Caballero, Paulo Roberto Oliveira Martins, Gustavo Cunha da Silva Neto, Florindo Anronio Ayres Júnior
Presenter: Marco Antonio dos Santos Caballero
doi://10.26678/ABCM.COBEM2023.COB2023-2176
Abstract
Digital controllers have gained popularity in recent years because of their ability to perform complex computations with high precision and speed. Moreover, they are highly versatile and efficient in managing non-linear control systems. This work describes the stages of plant modeling, simulation, control design of RST digital controllers and their implementation based on a programmable logic controller (PLC) for an industrial tank's water level control bench. The system presents slow first-order dynamics with time delay, centrifugal pump power saturation, and dead zone until reaching the operating range. The digital controller design was carried out through the pole placement technique for the tuning process requiring settling time reduction, zero steady-state error, and robustness. For implementation, the R, S, and T coefficients were calculated through the Diophantine equation, and the programming was developed using Ladder logic on the software CCW (Connected Components Workbench). Five digital controller strategies using the RST structure were designed, namely: a classical PID, a two degree-of-freedom PID, two types of RST with additional poles and an RST with Model Reference Control. All the controllers were simulated and experimentally tested on the bench. For tracking tests sequential multiple steps, either up and down, were performed in different operating regions and for regulation and robustness evaluation single step tests with plant input and output disturbances were also carried out to proceed with a comparative performance analysis of the different strategies. The integral of time absolute error (ITAE) criterion, settling time, peak overshoot and peak time were evaluated. It was observed that the five RST strategies developed in this work met the design requirements satisfactorily, enabling a shorter settling time, zero steady-state error and good robustness performances. It was found that the designed digital controllers achieved better result performances in the step-up stages. The high-order RST controllers and MRC RST presented better results than the PID ones.
Keywords
Digital Control, Feedback Level Control, Pole Placement, RST, PLC
