The availability of a mathematical description of a manufacturing process provides a quantitative basis for process control that is understood as maintaining the desired status of the process in spite of many external and internal disturbance effects. The desired status is defined by the set points, also known as reference signals that represent the desired numerical values of controlled variables of the process. The control task implies that the difference between the actual and desired process variables (error) is determined, and on the basis of this difference and according to the control law, the control efforts are defined and applied to the process. The manner in which the control effort drives the system from its actual state to the desired state, and the allowable discrepancy between the actual and the desired states are quite important. They are dependent on the control law and are explicitly defined by the design specifications along with the discrete time step (or clock frequency). Modern computer systems facilitate every function of the control task; process monitoring, specification of the set points, extraction of the errors, implementation of the control law, and the application of control efforts.
Discrete-time control Classical and state-variable control Decoupling control Adaptive control
This is a preview of subscription content, log in to check access.