 Hello friends, I am Milka Jagle working as an assistant professor in Department of Mechanical Engineering, Vulture Institute of Technology, Solapur. Today we are going to study of automatic control systems, what are automatic control systems and classification regarding that. So let's start. At the end of the session, students will be acquainted with basics of control system and identify different control systems. What is automatic control engineering? Automatic control engineering has played an important role in advancement and improvement of engineering skills. Control systems are integral part of the modern industrialization, industrial process and home appliances. Every activity in our day to day life is influenced by some sort of control system. This presentation includes concept of system and control systems. What is system? System is a combination or arrangement of different physical components which act together as an entire unit to achieve certain objective. Let's take an example of classroom. A classroom is a good example of physical system. A room along with the combination of benches, blackboard, fans, lightning arrangement can be called a control classroom which acts as an elementary system. A lamp made up of glass filament is a physical system. A kite made up of paper and sticks is an example of physical system. What is control system? To control means to regulate, to direct or to command. Hence, a control system is an arrangement of different physical elements connected in such a manner so as to regulate, direct or command itself or the other system. If in a classroom, professor is delivering his lecture, the combination becomes a control system as he tries to regulate, direct or command the students in order to achieve the objective which is to impart a good knowledge to the students. If a lamp is switched on or off using a switch, the entire system can be called a control system. I just want to pause the video for few seconds and think about different control system that you come across in your day to day life. So, this is a classification of control system. Control systems are broadly classified as follows, natural control system, manmade control system, combinational control system, time variant and time invariant control system, linear and non-linear control system, continuous time and discrete time control system, deterministic and stochastic control system, lamp parameter and distributed parameter control system, CSO, single input, single output and MIMO, multiple input, multiple output and the last open loop and closed loop control system. Let's see each control system in detail. First one, natural control system. The biological systems inside human being are of natural type. Human body is one of the good example of natural control system, regulation of temperature of human body. Second, manmade control system. The various control systems we are using in a day to day life which are designed and manufactured by human beings such as accelerator and braking system. And here comes the next combinational control system. As the name indicates combinational control system is a combination of natural and manmade together. Example will take here driver driving the vehicle. For successful operation of the system it is necessary that natural control system of driver along with the system in the vehicle must be active. Time variant control system. In this all the parameters vary with respect to time. Example will take here of space vehicle. As the space vehicle leaves the earth surface the mass of that goes on decreases, decreasing and here mass is the parameter. The next come time invariant control system. All the parameters in the system if it does not vary with respect to time the system is known to be time invariant control system. In case of rocket aerodynamic damping it goes on changing as the air density goes on changing. Here the next come linear system. A system is called to be linear system if the principle of superposition is valid that is it has to follow the two rules. First additive property, second homogeneity. If the system does not follow the principle of superposition then the system is said to be non-linear system. Here the output is directly proportional to the input in linear and in non-linear the output is not proportional to the input. Here a continuous time control system. All the system variables are function of a continuous time variable t. Example analog system, speed control of DC motor using tacho generator feedback. Next discrete time control system. In this one or more system variables are known at discrete time interval. Example digital system, microprocessors or computer-based systems. Next deterministic control system. The system in which output can be predicted due to changes in the input entering into the system. Stochastic control system. System in which output cannot be predicted due to changes in the input entering into the system or external disturbances. Lamped parameter control system. In this it is a system in which whose equation of operation is ordinary differential equation. Example electrical networks with different parameters like resistance and inductance. Distributed parameter control system. These are the systems in which equation of operation is partial differential equation. Example transmission line having its parameters, resistance and inductance totally distributed along it. Here comes the CISO that is name itself indicates a system having only single input and single output is called as CISO control system. Multiple input and multiple output are nothing but a system having multiple input and multiple outputs is called as MIMO. Here comes open loop control and closed loop control system. Open loop control system. A system in which input signal is independent on output signal. Here the input is given to the process and we get the output. The next come closed loop feedback system. Here a system in which input signal is dependent on the output signal. Here the output is given back to the input so that the output is controlled by the input. Here a feedback element is introduced. So let's see what is feedback. Feedback is a key tool that can be used to modify the behavior of a system. Feedback compares output signal with input signal in order to generate error signal to achieve or generate desired output. Feedback is present in closed loop control system. So these are the references book by UA Bakshi and the other book automatic control engineering by Francis Raven. Thank you.