**Control Systems History**

Likewise many systems around us in the environment, automatic control systems are also very related with the nature. Human body can be referred as the most important example of this fact. Pancreas which adjusts the blood sugar, the adrenaline which is increased to carry oxygen to the cells with the help of heart beat when the human body goes up to higher altitudes, are some of the major automatic control systems working in human body.

The idea of automatic control systems has a long history beginning from ancient times. The oldest control system is the flow rate control developed by Ktesibios in Alexandria in the third century(B.C.). This method is used for the control of flow rate in clepsydra. Filyon from Byzantion studied on the control of oil level in the Kerosene lamps. Heron developed a regulator for constant liquid flow in the first century (D.C.). The water flows with a constant speed (v) by the help of a buoy and flush in the regulator.

Cornelis Drebbel invented a control system for the temperature of a brooder in 1620. The temperature sensor used in the system consists of alcohol and mercury inside and a glass carrier filled with water outside of the sensor. When the fire heats the box and water, alcohol expands and the arm moves upright to allow the damper to get closer to the top of the chimney. When the box cools down, the damper is pulled down by the arm and the fire blazes up. The desired value of the temperature is adjusted with the length of the arm.

The first example of velocity control in the history is the rotating pendulum also called "Governors" which was first applied in windmills. James Watt also used this system for the steam engines in 1788.

The first mathematical study about control systems is the stability analysis in the article "On Governors " written by J. C. Maxwell in 1868. Maxwell first obtained the differential equations of the governor and linearized the nonlinear equations around an equilibrium point. Finally, he proved that the stability of a linear system can be guaranteed as long as the poles of the system are negative. E.J. Routh awarded for his development of stability criteria depending on the characteristic equation in 1877. Russian mathematician A. M. Lyapunov studied on the stability of motion systems, and made research about motion by the help of non-linear differential equations. Lyapunov's reearch provided a basis for state-space approach but this approach had not been in the academic literature until 1958.

After the researches in the late 1800s, Nyquist developed stability analysis with the frequency response in 1932 and Callendes developed the first PID control system in 1936.

W. R. Evans who studied on flight control, developed the root locus method which deals with the system response according to parameter change in characteristic equation. The feedback amplifier which was promoted by Bellman and Kabala in 1964, has an important role in feedback control systems.

The researches and developments in automatic control systems also proceed with the help of new technologies nowadays and the control systems have become an important part of our daily life.

**A Brief History of the Deparment**

The department established in 1993 as a “Sub-Department of Control and Command Systems “ with one compulsory and two elective courses within “ Faculty of Electrical-Electronics, Department of Electrical Engineering” was started to education under the name of “ Department of Control and Automation Engineering” thanks to the projects developed, the doctoral students, the industry collaborators as well as the teaching staff joined us.