1. Discuss the Need for Sensors and highlight some of the characteristics of
Sensors.
NEED:-
• Sensors are omnipresent. They embedded in our bodies, automobiles, airplanes, cellular
telephones, radios, chemical plants, industrial plants and countless other applications.
• Sensors in industrial applications being used for process control, monitoring, and safety, and in
medicine being used for diagnostics, monitoring, critical care, and public health.
• sensors for exploring space and improved environmental monitoring.
• Without the use of sensors, there would be no automation!
CHARACTERISTICS:-
Range : the difference between the maximum and minimum value of the sensed parameter
Resolution: The smallest change the sensor can differentiate.
Sensitivity: It is the ratio of change in output to a unit change of the input.
Error: Error is the difference between the result of the measurement and the true value of the
quantity being measured
Accuracy: It is the difference between measured value and true value
Precision: Precision is the ability to reproduce repeatedly with a given accuracy.
Repeatability: The ability of a sensor to give same output for repeated applications of same input
value.
Repeatability = (maximum – minimum values given) X 100 ⁄ full range.
Impedance: It is the ratio of voltage and current flow for sensor. For a resistive sensor, the
impedance Z is same as the
resistance R& its unit is ohms.
Response time: Response time is the amount of time required for a sensor to respond completely
to a change in input.
2. Explain the physical or chemical sensing principles of transduction.
,3. Explain with a neat diagram the components of measurement system.
4.What is a Sensor? Briefly explain the classification of sensors.
SENSOR- A device that detects the changes in electrical or physical or other quantities and
thereby produces an output as an acknowledgement of change in the quantity is called as a
Sensor. Generally, this sensor output will be in the form of electrical or optical signal.
Classification of Sensors
Sensors can be ranked into various classification systems, but for the sake of
simplification, we have divided them into 5 core classifications.
1. Active and Passive Sensors
◦ Active Sensors (also known as parametric sensors) are sensors that
require an external power source to operate. Examples of active
sensors include GPS sensors and radar sensors.
◦ Passive Sensors (also called self-generated sensors) generate their
own electric signal and do not require any external power source.
Examples of passive sensors include thermal sensors, electric field
sensing, and metal detecting.
2. Contact and Non-Contact Sensors
◦ Contact Sensors are those that require physical contact with their
stimulus. Familiar examples of contact sensors are temperature and
strain gauge sensors.
◦ Non-Contact Sensors, on the other hand, require no physical contact.
These types of sensors include optical and magnetic sensors, as well
as infrared thermometers.
3. Absolute and Relative Sensors
◦ Absolute Sensors mimic its name by providing an absolute reading of
its stimulus. For example, a thermistor always measures the exact, or
absolute, temperature reading.
◦ Relative Sensors provide measurement to a fixed or variable
measurement. An example of a relative sensor would be a
thermocouple, where the temperature difference is measured, not the
actual temperature.
4. Analog and Digital Sensors
◦ Analog Sensors produce continuous analog output signals,
proportional to its measurement. A few examples of analog sensors
are: accelerometers, pressure sensors, light, and sound sensors.
, ◦ Digital Sensors (also known as electronic or electrochemical sensors)
convert the data transmission, digitally. Examples include digital
accelerometers, pressure, and temperature sensors.
5. Miscellaneous Sensors
◦ Of course, there are plenty of other types of sensors in the field and
they would fall under the ‘other’ or miscellaneous category. These
include electric, biological, chemical, radioactive and more.
5.Explain the static characteristics of sensor.
Static Characteristics of Sensors
Static characteristics of sensors describe the performance of a transducer with
very slow changes in the measurand. Static characteristics include accuracy,
linearity, precision, sensitivity…etc
Error
Accuracy of a sensor is usually specified by error. it tells you how closely the
measured value matches the true value.
Error is given by
Where t stands for true value, m for measured value and x stands for the
measurand.
For multi error systems, the overall error can be assessed either through finding
the linear sum of all errors (E1 + E2 +…+En) or through the root mean square
approach where total performance error can be assessed as,
Sensors.
NEED:-
• Sensors are omnipresent. They embedded in our bodies, automobiles, airplanes, cellular
telephones, radios, chemical plants, industrial plants and countless other applications.
• Sensors in industrial applications being used for process control, monitoring, and safety, and in
medicine being used for diagnostics, monitoring, critical care, and public health.
• sensors for exploring space and improved environmental monitoring.
• Without the use of sensors, there would be no automation!
CHARACTERISTICS:-
Range : the difference between the maximum and minimum value of the sensed parameter
Resolution: The smallest change the sensor can differentiate.
Sensitivity: It is the ratio of change in output to a unit change of the input.
Error: Error is the difference between the result of the measurement and the true value of the
quantity being measured
Accuracy: It is the difference between measured value and true value
Precision: Precision is the ability to reproduce repeatedly with a given accuracy.
Repeatability: The ability of a sensor to give same output for repeated applications of same input
value.
Repeatability = (maximum – minimum values given) X 100 ⁄ full range.
Impedance: It is the ratio of voltage and current flow for sensor. For a resistive sensor, the
impedance Z is same as the
resistance R& its unit is ohms.
Response time: Response time is the amount of time required for a sensor to respond completely
to a change in input.
2. Explain the physical or chemical sensing principles of transduction.
,3. Explain with a neat diagram the components of measurement system.
4.What is a Sensor? Briefly explain the classification of sensors.
SENSOR- A device that detects the changes in electrical or physical or other quantities and
thereby produces an output as an acknowledgement of change in the quantity is called as a
Sensor. Generally, this sensor output will be in the form of electrical or optical signal.
Classification of Sensors
Sensors can be ranked into various classification systems, but for the sake of
simplification, we have divided them into 5 core classifications.
1. Active and Passive Sensors
◦ Active Sensors (also known as parametric sensors) are sensors that
require an external power source to operate. Examples of active
sensors include GPS sensors and radar sensors.
◦ Passive Sensors (also called self-generated sensors) generate their
own electric signal and do not require any external power source.
Examples of passive sensors include thermal sensors, electric field
sensing, and metal detecting.
2. Contact and Non-Contact Sensors
◦ Contact Sensors are those that require physical contact with their
stimulus. Familiar examples of contact sensors are temperature and
strain gauge sensors.
◦ Non-Contact Sensors, on the other hand, require no physical contact.
These types of sensors include optical and magnetic sensors, as well
as infrared thermometers.
3. Absolute and Relative Sensors
◦ Absolute Sensors mimic its name by providing an absolute reading of
its stimulus. For example, a thermistor always measures the exact, or
absolute, temperature reading.
◦ Relative Sensors provide measurement to a fixed or variable
measurement. An example of a relative sensor would be a
thermocouple, where the temperature difference is measured, not the
actual temperature.
4. Analog and Digital Sensors
◦ Analog Sensors produce continuous analog output signals,
proportional to its measurement. A few examples of analog sensors
are: accelerometers, pressure sensors, light, and sound sensors.
, ◦ Digital Sensors (also known as electronic or electrochemical sensors)
convert the data transmission, digitally. Examples include digital
accelerometers, pressure, and temperature sensors.
5. Miscellaneous Sensors
◦ Of course, there are plenty of other types of sensors in the field and
they would fall under the ‘other’ or miscellaneous category. These
include electric, biological, chemical, radioactive and more.
5.Explain the static characteristics of sensor.
Static Characteristics of Sensors
Static characteristics of sensors describe the performance of a transducer with
very slow changes in the measurand. Static characteristics include accuracy,
linearity, precision, sensitivity…etc
Error
Accuracy of a sensor is usually specified by error. it tells you how closely the
measured value matches the true value.
Error is given by
Where t stands for true value, m for measured value and x stands for the
measurand.
For multi error systems, the overall error can be assessed either through finding
the linear sum of all errors (E1 + E2 +…+En) or through the root mean square
approach where total performance error can be assessed as,
