VU 325.038 Fundamentals of Automatic Control
What ist Automatic Control?
Automatic Control is an important part of automation technology. The automation technology itself is characterized by automatically working machines and devices, which together can form extremely complex industrial processes and systems. A key task of control engineering is to allow such processes and systems to follow specified reference variables or target functions as well as possible. These can be, for example, movement trajectories of robots, pressures, temperatures and concentrations in a chemical process, the speed of a turbine or the speed of a vehicle.
The Automatic Control generally uses one or more actuators that act on the system and thus make it possible to influence it appropriately. Control engineering also means continuous measurement of the variable to be influenced (controlled variable) in the controlled system and comparison with the desired value (command variable or setpoint). From this, a control algorithm determines one or more manipulated variables that influence the system appropriately via the actuators in order to minimize the deviation. If additional disturbances affect the system, then these should affect the variables to be controlled as little as possible. This is also the task of the control algorithm.
The methods of Automatic Control are essentially based on the description and analysis of the systems to be controlled, the so-called system theory. Today, systems theory has a highly interdisciplinary character, as a wide variety of disciplines such as mathematics, physics and chemistry interact. The systems theory includes a consistent mathematical description of processes and systems according to the cause and effect principle. This means that systems theory is able to represent the causal relationship of complex technical processes and systems independently of technological details. The mathematical methods of systems theory and control engineering have also established themselves in completely non-technical disciplines such as biology or economics in recent years.
Content of the Lecture
The lecture covers the basics of classical control engineering using design and description methods in the time and frequency domain. In the most varied of control tasks, similar structures and problems are found again and again that are common to all applications. Therefore, the use of control engineering methods is largely independent of the respective application.
It is essential for a uniform treatment that the present technical problem is described in a very abstract way. The focus of the LVA is the input/output behavior of linear dynamic systems. First, however, it is explained how non-linear systems can be approximately described by linear differential equations. The dynamic behavior of individual control circuit elements is also analyzed and characterized in the image area with the help of the Laplace transformation. The analysis of more complex dynamic systems is made possible using block diagram algebra.
This is followed by an analysis and representation of linear systems in the frequency domain (e.g. using the Bode diagram). The concept of feedback is discussed in detail as an essential part of a closed control loop. After that, the investigation of the stability in the time domain and in the frequency domain as well as the discussion of the requirements for the dynamic behavior of the closed control loop lead to different design methods for practically relevant controllers (P, PD, PID). The behavior in the event of faults is also taken into account. At the end of the course, basic tools and methods are available to specifically influence the behavior of a given dynamic linear system through analysis and subsequent controller synthesis.