In the long-term production and life, in order to reduce their own labor, ancient humans gradually developed the desire to replace human and animal power with natural forces and some complex mental activities with automation devices. After years of exploration, they independently made some primitive automation devices. About the middle of the third century BC, Stacy Beus of Alexandria first used the float in the pot. According to the samples recovered by Diels at the beginning of this century, the injected water is controlled by a conical float. And this kind of abstemious way already contains the idea of negative feedback (although it was not clear at that time). In 500 BC, China's army had used the clepsydra as a timing device. About AD 120, the famous scientist Zhang Heng (78- 139, Eastern Han Dynasty) put forward an ingenious method to solve the problem of inaccurate timing with the decrease of water head with a compensation pot. In his "Water Leaks to the Ammunition", there are not only floats and leaking arrows, but also siphons and at least one compensation pot. The most famous water clock in China, "Copper Pot Dripping Water", was built in 13 16 (the third year of Yuan Dynasty) by Du Zisheng, a coppersmith, and has been in use until 1900. In addition, in 350 BC, China had used a mortar with a structure similar to a waterwheel to grind rice; In 50 BC, waterwheels were used to divert water for irrigation; In 3 1 year BC, the forging factory began to use hydraulic bellows. It greatly lightens people's labor. Although these automatic devices are not as advanced as some automatic control devices now, and there is no systematic theoretical support, their inventions have played a leading role in the formation of automatic control. With the continuous improvement and development of these automatic control devices, automatic control technology has gradually formed. We set the formation period of automatic control technology at the end of 18 as the 1930s. People use automatic control instead of manual control of various mechanical equipment, which is a great pioneering work in human history. There are many representative inventions in this period. 1750, Andrew Mikel introduced the "fan tail" transmission device for the windmill, which made the windmill automatically face the wind. Subsequently, William Cupid improved the automatic shutter wing, so that it can automatically adjust the transmission speed of the windmill. This adjustable regulator has been patented by 1807. 1788 British mechanic J. Watt invented the centrifugal governor, and Watt connected it with the valve of the steam engine to form a closed-loop automatic control system for the speed of the steam engine. Watt's invention initiated a new era in the application of modern automatic regulating devices, which had an important impact on the first industrial revolution and the subsequent development of control theory.