摘要
Key to any control system is a mechanism that regulates cer-tain attributes of a dynamic system,engineered or natural.In this field of profound impacts to all branches of engineer-ing,know-how is distinguished from know-why,practice from understanding,and experience from knowledge.The practice of automatic control in the modern era began with the eighteenth century flyball governor,the predecessor of today's industry-dominant PID technology,and its theory with the 1868 paper of James Clerk Maxwell,titled simply"On Governors".
