Review Lecture: The control of industrial processes

All sections of Industry are concerned to improve the efficiency of their production methods and, in general, this can only be achieved either by the design of new plant employing more efficient processes or by better control of existing plant. Almost all manufactured goods involve a very large number of processes and more often than not a large number of different components have to be assembled together in order to produce the finished article. The objective in any factory is to produce a specified quantity of goods for the lowest possible cost and if this is to be achieved it is evident that control must be exercised at a number of different levels in the factory. Not only must each machine be producing components in the most efficient manner but, when they have been produced, the different components must be brought together at the assembly line in the right proportions and at the right time for the assembly to continue both smoothly and efficiently. Most, if not all, factories produce closely specified products from closely specified raw materials; the plant is designed, built and maintained to do just this and so it might be expected that there is no control problem. Unfortunately, however, there are very few factories which are required to produce exactly the same product day in day out for the whole of their useful lives. Even in the giant basic industries like Electricity and Oil we find that although in the Oil industry the products remain the same the relative quantities required differ from summer to winter, while in Electricity although there is only one product, which, by act of Parliament, has to be maintained within very close limits, the quantity required is continually changing and so power stations have to be switched in and out sometimes at short notice. In Industry, therefore, the first control problem is to estimate the quantities of the different products which have to be manufactured.