The field of process control is concerned with the analysis of dynamic behavior of chemical processes, process simulation, design of automatic controllers, and associated instrumentations. Process control as practiced in the process industries has undergone significant changes since it was first introduced in the 1940's. Perhaps the most significant influence on the changes in process control technology has been the introduction of inexpensive digital computers and instruments with greater capabilities than their analog predecessors. During the past 20 years automatic control has assumed increased importance in the process industries, which has led to the application of more sophisticated techniques.
Encyclopedia of Physical Science and Technology, 3rd edition, Vol. 13, Academic Press, San Diego, California, pp. 111-126 (2001)