Electronics control presentation
23
Introduction Many of the devices used in the home or in industry require an electronic control system so that they can operate correctly. A control system is interconnection of components forming a system configuration that will provide a desired response. Practically every aspects of our day-to-day life is affected less or more by some control system. A bathroom toilet tank, a refrigerator, an air conditioner, a geezer, an automatic iron, an automobile all are control system.
-
Upload
xavierpaulino -
Category
Engineering
-
view
130 -
download
3
Transcript of Electronics control presentation
IntroductionMany of the devices used in the home or in
industry require an electronic control system so that they can operate correctly.
A control system is interconnection of components forming a system configuration that will provide a desired response.
Practically every aspects of our day-to-day life is affected less or more by some control system. A bathroom toilet tank, a refrigerator, an air conditioner, a geezer, an automatic iron, an automobile all are control system.
Requirement Of Good Control System
Accuracy: error detector should be present in control system to increase accuracy
Sensitivity : It should be sensitive to input signal onlyNoise : control system should be able tor reduce
noise effect for better performanceStability: system must be able to remove offsetBandwidth: bandwidth should be large as possible
for frequency responseSpeed :This is the time taken by control system to
achieve its stable output
Types Of Control Systems
There are two main types of control system.
They are as follow:
Open loop control system
Closed loop control system
Open loop control system
Open-loop control systems are the systems in which the output has no effect on the control action.
In other word an open loop system is a system without feedback.
Block diagram of Open loop control
Examples of open loop control system1.Open-loop Drying System
An operator would set a timer (controller) to say 30 minutes and at the end of the 30 minutes the drier will automatically stop and turn-off even if the clothes are still wet .
In this case, the control action is the manual operator assessing the wetness of the clothes and setting the process accordingly
So in this example, the clothes dryer would be an open-loop system as it does not monitor or measure the condition of the output signal, which is the dryness of the clothes. Then the accuracy of the drying process, or success of drying the clothes will depend on the experience of the user (operator).
Examples of open loop control system…
2. Open loop alarm system
The function of the sensor is to collect data regarding the concerned house.
When the electronic sensor is triggered off (for example, by the entry of an unauthorized person), it will send a signal to the receiver.
The receiver will then activate the alarm, which will in turn generate an alarm signal. The alarm signal will not cease until the alarm is stopped manually.
Block diagram of an open loop control system (burglar alarm)
Examples of open loop control system
3.A simple electric fire is used to heat a room
When the supply is turned on, the room temperature increases. However, without any further intervention the room will probably become too warm. The only way to correct this would be to turn off the supply.
Examples of open loop control system
4. TV Remote control
Examples of open loop control system
5. Microwave Oven
Advantages of open loop system
Simple in construction and design.
Economical.
Easy to maintain.
Generally stable.
Convenient to use as output is difficult to measure.
Disadvantages of open loop system
They are inaccurate.
They are unreliable.
Any change in output cannot be corrected automatically.
Closed loop control system Control system in which the output has an effect on the input
quantity in such a manner that the input quantity will adjust itself based on the output generated
In other word a closed loop system is called a feedback control system.
Examples of closed loop control system
1.Closed -loop Drying System
This sensor would monitor the actual dryness of the clothes andcompare it with (or subtract it from) the input reference.The error signal (error = required dryness – actual dryness) isamplified by the controller, and the controller output makes thenecessary correction to the heating system to reduce any error.For example if the clothes are too wet the controller may increasethe temperature or drying time. Likewise, if the clothes are nearlydry it may reduce the temperature or stop the process so as not tooverheat or burn the clothes
Examples of closed loop control system…
2.Closed -loop heating system control
The temperature sensor is installed in the room to be controlled and sends a signal back along the feedback path to the comparison device incorporated in the controller.The comparison device compares the value of temperature at the sensor to that of the desired value or set point on the controller.
Examples of closed loop control system…
3.human-operated liquid-level control system.
In the human-operated system, the eyes, brain, and muscles correspond to the sensor, controller, and pneumatic valve respectively.
Examples of closed loop control system…
4. Elevator control system.
Examples of closed loop control system…
5. Traffic collision avoidance system TCAS
Advantages of closed loop control system
Closed loop control systems are more accurate even in the presence of non-linearity.
Highly accurate as any error arising is corrected due to presence of feedback signal.
Bandwidth range is large.
Facilitates automation.
The sensitivity of system may be made small to make system more stable.
This system is less affected by noise
Disadvantages of closed loop control system
They are complicated to design.
Required more maintenance.
Feedback leads to oscillatory response.
Overall gain is reduced due to presence of feedback.
Stability is the major problem and more care is needed to design a stable closed loop system.
Difference between closed loop and open loop system
TRACKING SYSTEM
A tracking system is the one which determines the location or direction of a target on a near-continuous basis.
An ideal tracking system would maintain contact and constantly update the target's bearing, range and elevation.
The difference between Tracking and Control System is that, the desired input in control system now comes from the tracker.
Example Of Control System
Radar Servo Control System
Example Of Tracking System
Radar Servo Tracking System
