introduction to control system
DESCRIPTION
Control systemsTRANSCRIPT
Topics to be covered….
IntroductionOpen-loop control Systems (OL)Closed-loop Control Systems (CL)Difference between OL and CL systemsLaplace TransformTransfer Function
Unit - 1 Introduction to control system
A control system Mechanism that alters the future of a system
consists of subsystems and processes assembled for the purpose of obtaining a desired output, e.g. a radio controlled car is an example of a basic control system. Other examples include…
Traffic Lights
Lifts
Microwave
Air Conditioning Systems
Theme Park Rides
Automatic Doors
Burglar Alarm
Train Networks Robots
What is a Control System?What is a Control System?
Security Lights
A control theory is a strategy to select appropriate inputs
Important Terminologies
Plant : physical object to be controlledSystem: It is a combination of components that act together and perform a certain objectiveInput: objective, stimulus, independent variable, desired response
Output: result, response, dependent variable, actual response
Introduction to control systemUnit - 1
Open loop Systems
- the output has no effect on the control action
- the output is not measured - the output is not compared back with the
reference input - It can not compensate for the effect of the
disturbance
Introduction to control systemUnit - 1
Closed loop Systems
- Also referred to as feedback control system
- Measures the output and compares the results from the reference or input. The difference between the two, is called error causes the actuating signal to drives the controller and correct correct the difference
- Compensates the effect of disturbances
Introduction to control systemUnit - 1
Introduction to control systemUnit - 1
Comparison of Systems
System Type Advantages Disadvantages
Open-loop control systems
1. Simple to construct and ease of maintenance
2. Less expensive than a closed-loop system
3. There is no stability problem
4. Convenient when output is hard to measure or measuring the output precisely is economically not feasible
1. The system response is very sensitive to external disturbance and internal variations in system parameters.
2. Recalibration is necessary from time to time in order to maintain the required quality of the output
Comparison of Systems
Unit - 1 Introduction to control system
System Type Advantages Disadvantages
Closed-loop control systems
1. Makes the system response relatively insensitive to external disturbances and internal variations in the systems parameters
2. Possible to use relatively inexpensive components.
3. Better control of the transient and steady-state response.
4. Increase accuracy5. Increased ability to
reproduce output with varied inputs
1. Risk of instability
2. Complex analysis.
3. Expensive implementation
Example of Laplace Transform
1. Given the differential equation, using Laplace, solve for y(t) if all initial conditions are zero (relaxed system). u(t) is a unity step function
𝒅𝟐𝒚 (𝒕)𝒅𝒕𝟐
+𝟏𝟐𝒅𝒚 (𝒕)𝒅𝒕
+𝟑𝟐𝒚=𝟑𝟐𝒖(𝒕)
Transfer Function
The transfer function is the ratio of the output Laplace Transform to the input Laplace Transform assuming zero initial conditions.