Simple diagnostic tool for improving control of manufacturing systems

The paper attempts to distil the principles of control theory into a form which is useful to managers and information-system designers. It develops a simple model, applicable to most companies, based on the four essential elements (aim, plan, action and feedback) and three levels (strategic, tactical and operational) of control. Applications of the model as an analytical tool are illustrated with actual cases from the steel industry. One shows how, with a complete system, control is achieved. The other, with weaknesses and omissions which the model identifies, shows a lack of control and the ensuing difficulties.