What is difference between modern control and conventional control theory?

Answer 1

Classical control typically deals with single-input single-output (SISO) systems using frequency domain tools. This means taking the Laplace transform of the equations of motion for the system (typically ordinary differential equations) and designing controllers based on performance specifications at low and high forcing frequencies.

Modern control is largely a result of the microprocessor, which allows large amounts of computation to be done cheaply. Modern control often deals with multiple-input multiple-output (MIMO) systems, and deals directly with the ordinary differential equations in the time domain. In modern control, we develop controllers that have good stability characteristics without using too much control (or actuation). There are a number of powerful tools from dynamical systems theory which allow us to find "optimal controllers", which are optimal with respect to some quadratic cost function.

Answer 2

Modern control theory often involves the use of state-space models, optimal control techniques, and robust control methods, while conventional control theory typically focuses on classical control techniques like PID controllers and frequency domain analysis. Modern control theory emphasizes a more systematic and mathematical approach to designing controllers, taking into account system dynamics and uncertainties. Conventional control theory is more empirical and based on heuristics developed through practical experience.