Robust controller design for position control of the metal ball in magnetic field

Abstract

Article is describing a modeling and controller synthesis for the position control of the metal ball in magnetic field. The focus was paid to implementation of modern control theory for the controller design. The position control of the metal ball in magnetic field is known unstable non-linear control problem that was solved with different methods and with variety of the control synthesis tools. Our aim in this article is to point out the use of modern control theory such as H/sub /spl infin// control theory and related difficulties by the implementation of the theory when solving real control problems. Controller design is a process composed with many steps and with even more obstacles and limitations. The article is presenting a systematic approach from problem studying to the final solution with all necessary steps, beside that the translation of performance demands to the H/sub /spl infin// controller synthesis tools is described as a case study. For a use of modern control theory a system robustness was the primarily reason. H/sub /spl infin// control theory is enabling a controller synthesis with assurance of the system robustness but there is also a possibility that the system will perform robust to the object perturbation and external disturbances regardless to the controller synthesis method. In article one such modified approach of the controller synthesis is presented. With the performance measurement results on the real system and comparison of those for two different controllers designed different ways we have cam to two important conclusions. First, that H/sub /spl infin// controller synthesis although mathematically very elegant can be a good deal of a problem when implemented on a real system and second, that is possible to achieve system robustness although using a different method of controller synthesis, important is only that the robustness is vaulted.