Chapter 1 PPT Flashcards
It helps in attaining optimal performance of dynamic systems, improving productivity, relieving the drudgery of many routing repetitive manual operations
Automatic Control
It is a pre-set closed-loop control system that requires no operator (human) action.
Automatic Control System
It uses application of mechanisms to the operation and regulation of processes without continuous direct human intervention
Automatic Control
An automatic control system has two process variables associated with it
Controlled variable and manipulated variable
It is a process variable that is maintained at a specified value or within a specified range
Controlled variable
It is a process variable that is acted on by the control system to maintain the controlled variable at the specified value or within the specified range.
Manipulated variable
In any automatic control system, the four basic functions that occur are:
Measurement, Comparison, Computation, Correction
It is a combination or an arrangement of different physical components which act together as an entire unit to achieve certain objective.
System
The portion of a system which is to be controlled or regulated
Plant
Any operation to be controlled
Process
It is an applied signal or an excitation signal applied to control system from an external energy source in order to produce a specified output
Input
It is the particular signal of interest or the actual response obtained from a control system when input is applied to it
Output
The element of the system itself or external tot the system which controls the plant or the process
Controller
It is a signal which tends to adversely affect the value of the output of a system.
Disturbances
Undesirable and unavoidable effects beyond our control, generated from outside process-environment and from within
If such disturbance is generated within the system itself, it is called as
Internal Disturbance
The disturbance generated outside the system acting as an extra input to the system in addition to its normal input, affecting the output adversely is called as an
External Disturbance
Classification of Control Systems
Natural Control System, Manmade Control System, Manual Control System, Manual Control System, Automatic Control System, Open-Loop Control System, Closed-Loop Control System, Linear vs Nonlinear Control System, Time invariant vs Time Variant, Continuous Data vs Discrete Data System, Deterministic vs Stochastic Control System
A control system in which output varies linearly with the input
Linear Control System
When the characteristics of the system do not depend upon time itself
Time invariant control system
It is a system in which one or more parameters vary with time
Time varying control system
All system variables are function of a continuous time t
Continuous data control system
It involves one or more variables that are known only at discrete time intervals
Discrete time control system
A control system is ____ if the response to input is predictable and repeatable
Deterministic Control System
Any physical system which does not automatically correct for variation in its output
Open-loop control system
In this system, output is dependent on input but controlling action or input is totally independent of the output or changes in output of the system.
Open-loop control system
A system that maintains a prescribed relationship between the output and the reference input by comparing them and using the difference as a means of control is called a
Feedback control system
The part of output, which is to be decided by feedback element is fed back to the reference input. The signal which is output of feedback element is called ___
feedback signal
The deviation of the actual output from its desired value is called an ____
error
It is an element which accepts the error in some form and decides the proper corrective action
Controller
It is the heart of the control system. The accuracy of the entire system depends on how sensitive it is to the error detected and how it is manipulating such an error.
Controller
Classification of Industrial Controllers
Two-position or on-off controllers, Proportional Controllers, Integral Controllers, Proportional-plus-integral controllers, proportional-plus-derivative controllers, proportional-plus-integral-plus-derivative controllers
The most elementary controller mode
Two-position or on-off controller mode
In this control mode, the output of the controller is simple proportional to the error
Proportional controller
A control mode used in control systems which is based on the history of the errors
Integral controllers
The controller produces a control action that is proportional to the rate at which the error is changing
Derivative controller
This is a composit control mode obtained by combining the proportional mode and the integral mode
Proportional + Integral controller
The series combination of proportional and derivative control mode
Proportional + Derivative Controllers
The composite controllers including the combination of the proportional, integral and derivative control
PID control mode
It will always result in an offset between measured value and desired value and for every load there will be a different steady state water level
Proportional Control
As the gain increases, the ___ decreases
offset
As the gain increases, the stability ___ until the system becomes unstable
decreases
It speeds up the removal of the offset
Derivative action
