Monitoring and control

Question 1

Monitoring system

Answer 1

A system that observes and often records the activities in a process

Question 2

Control System

Answer 2

A system that manages or regulates a process by physically changing aspects of the system depending on collected data.

Question 3

Sensors

Answer 3

An input device that collects data from the surrounding physical environment

Examples of sensors including:
light/UV, temperature, pressure, humidity, sound, infrared, touch sensors, electromagnetic field sensors and proximity sensors

Uses:
-Weather stations use temperature sensors to measure ambient temperature
-Pressure sensors to measure atmospheric pressure
-Humidity sensors to measure absolute and relative humidity
-Light sensors to measure sunlight, monitoring water pollution
-Weather stations
-Environmental monitoring

Question 4

Advantages of sensors

Answer 4

-Data can be repeatedly collected 24hrs a day, thus humans does not need to be present all the time and can rest

-Data can be collected in harmful and dangerous environments, without the presence of humans. Therefore, lives of humans are not at risk to collect the data.

-A Sensor may be more consistent in collecting data, as its a mechanical device, thus is more accurate. Humans may be inconsistent, thus could lead to errors in data samples.

Question 5

Disadvantages:

Answer 5

-Can wear and tear, thus become faulty. which will lead to incorrect readings being recorded, could be detrimental to the whole system.

-Thus sensors can be put through calibration to make sure it takes accurate readings

Question 6

Calibration

Answer 6

The process of testing and modifying a device to make sure that it is taking the correct readings.

Question 7

Importance of calibration:

Answer 7

-The accuracy of all sensors reduces after a period of time, due to constant use in/exposure to the atmosphere

-Regular calibration helps to maintain the accuracy of the sensors/helps to make sure sensors produce accurate/correct/reliable readings

-Other devices within a monitoring system may deteriorate over time resulting in a need for recalibration

Question 8

Types of calibration:

Answer 8

• One point: Simplest form, Used to correct an offset calibration curve
• Two point: Correct data set suffering both offset and sensitivity
• Multipoint: Similar to other calibration methods, uses many different readings (at least 3)

Question 9

Method of performing one point calibration:

Answer 9

-Take a reading with the sensor

-Compare the reading with a device measuring at the ideal standard

-Subtract the reading from the reference to get the offset

-Add the offset to every reading to get the calibrated value.

Question 10

Method of performing Two point calibration:

Answer 10

-Take two different readings with your sensor, Lower end of scale and higher end

-Compare the readings to readings from a device measuring at ideal standard

-Calculate the range value for sensor readings by subtracting low reading from the high reading

-Calculate the range value for the ideal standard by subtracting low reading from the high reading

-Use formula to calculate the correct value for each reading:

CorrectValue = (((SensorCurrentValue - SensorLowValue) * IdealRangeValue) / SensorRangeValue) + IdealLowValue.

Question 11

Differences between one point calibration and two point calibration:

Answer 11

-Only one measurement point/reading with one point calibration whereas with two point calibration at least two readings are taken
-One point calibration is appropriate for sensors used to measure a value that
is constant, whereas two-point calibration is used with sensors that measure a
constantly changing variable
-With one point calibration the offset only is calculated, the offset is then added to every subsequent reading
-With two point calibration sensitivity needs to be included not just an offset
-Two point calibration is used where there is a linear relationship between the two readings

Question 12

Microprocessor:

Answer 12

An integrated circuit that is used in monitoring and control systems

Question 13

Actuator:

Answer 13

A type of motor that is used to move and operate another mechanism or device

Question 14

Examples of control technology systems include:
Microprocessor controlled:

Answer 14

glass/greenhouses
central heating systems
air conditioning systems
burglar alarms
control of traffic/pedestrian flow
car park barriers
traffic lights
Wireless Sensor and Actuator Networks
smart homes

Question 15

Advantages of Microprocessors:

Answer 15

-They can be programmed to execute several different tasks

-They are small in size so can be easily built into different technologies

-They are relatively fast at moving data between different memory locations

Question 16

Disadvantages of Microprocessors:

Answer 16

-There is a limit on the size of the data they are able to handle

-They are only small in size and can overheat if too much demand is placed on them

Question 17

Advantages of Actuators:

Answer 17

-Hydraulic and electric actuators are fairly quiet

-The cost of pneumatic actuators is relatively low

-Most actuators have moderate to high speed abilities to perform an action

Question 18

Disadvantages of Actuators:

Answer 18

-Pneumatic actuators can be quiet noisy

-The cost of hydraulic and electric actuators is relatively high

-Fluid leaks can be a problem in hydraulic actuators

Question 19

Example of a control system: Air conditioning

Answer 19

1. User sets the temperature to 22 degrees celcius
2. The value is stored
3. A temperature snesor collects data about the ambient temperature
4. The data collected by the sensor is sent to the microprocessor, data is converted from analogue to digital
5. The microprocessor analyses each data sample sent to see if it is equal to the stored value (22)
6. if the data sample is greater than 22 degrees, microporcessor sends a signal to an actuator, triggering the system to increase the cooling function
7. If data sample is less than 22 degrees, the microprocessor sends signal to the actuator to trigger the system to increase the heating function
8. If the data sample is equal to 22 degrees, no action is taken
9. The whole process is then repeated at a set time interval, Ex: once every minute

Question 20

Algorithm:

Answer 20

A set of instructions or steps to be followed to achieve a certain outcome.