Towards Online Model Predictive Control on a Programmable Logic Controller: Practical Considerations

Given the growing computational power of embedded controllers, the use of model predictive control (MPC) strategies on this type of devices becomes more and more attractive. This paper investigates the use of online MPC, in which at each step, an optimization problem is solved, on both a programmable automation controller (PAC) and a programmable logic controller (PLC). Three different optimization routines to solve the quadratic program were investigated with respect to their applicability on these devices. To this end, an air heating setup was built and selected as a small-scale multi-input single-output system. It turns out that the code generator (CVXGEN) is not suited for the PLC as the required programming language is not available and the programming concept with preallocated memory consumes too much memory. The Hildreth and qpOASES algorithms successfully controlled the setup running on the PLC hardware. Both algorithms perform similarly, although it takes more time to calculate a solution for qpOASES. However, if the problem size increases, it is expected that the high number of required iterations when the constraints are hit will cause the Hildreth algorithm to exceed the necessary time to present a solution. For this small heating problem under test, the Hildreth algorithm is selected as most useful on a PLC

Robust Complexity Criteria for Nonlinear Regression in Narx Models

Many different methods have been proposed to construct a smooth regression function, including local polynomial estimators, kernel estimators, smoothing splines and LS-SVM estimators. Each of these estimators use hyperparameters. In this paper a robust version for general cost functions based on the Akaike information criterion is proposed

Using code generated by MATLAB for the Mold Level Control System of a Continuous Slab Caster in ArcelorMittal Gent

The stability of the mold level in continuous slab casting machines is an important factor determining the final quality of flat carbon steel. The existing performant feedback control system of Slab Caster 2 in the Steel Shop of ArcelorMittal Gent will be extended with a feedforward signal using the predicted mold level. A prediction algorithm, an early warning detection system and detailed FFT analysis of the mold level variations have been designed in MATLAB-Simulink. PLC code is generated directly from the MATLAB design, and will be implemented in a PLC serving as PROFINET I-Device in the base automation of slab caster KG2.status: publishe