MECHATRONICS UPDATED COMPREHENSIVE EXAM
QUESTIONS AND SOLUTIONS RATED A+
✔✔Dead band - ✔✔range within which sensor cannot measured
✔✔Resolution - ✔✔smallest value that can be resolved (detected) by the sensor
✔✔Accuracy - ✔✔measure of how close the output value represent the actual value of
the physical quantity being sensed
✔✔level in n bit? - ✔✔2^n
✔✔Noise - ✔✔random variation of the output independent of the measured value
✔✔hystersis - ✔✔systematic error where the direction of change of measured value
affects the value. The output of a sensor is dependent on the time derivative of the
measured value.
✔✔non-linearity - ✔✔measure of systematic deviation from proportionality across the
range of the sensor.
✔✔(temporal) stability or drift - ✔✔measure of how much output value changes with
time independent of the the input value
✔✔thermal stability or drift - ✔✔measure of the systematic change in output value due
to change in temperature
✔✔Sensitivity - ✔✔relationship between the scale of the measured quantity and the
scale of the electrical output, given in (electrical unit)/(physical unit)
✔✔Temporal response - ✔✔ability of any sensor to measure a quantity that changes in
time is limited by its temporal response
✔✔Time constant
(Temporal response) - ✔✔measure of time taken for the out signal to reach a level
following a step change in inout
✔✔Settling time
(Temporal response) - ✔✔time taken for output value to reach 90% of its final value
✔✔Rise time
(Temporal response) - ✔✔time taken for the output to reach a certain value
✔✔Bandwidth
, (Temporal response) - ✔✔a frequency domain measure of the change in the sensor
amplitude response with frequency variation of the measured quantity.
✔✔Supply voltage/current - ✔✔electrical supply to work
✔✔Rated - ✔✔value use to test the sensor in order to determine the values of
parameters whilst the sensor is operational
✔✔Mechanical Parameters - ✔✔1. Physical Dimension
2. Mass
3. Mounting
4. Packaging style
5. Shock resistance
6. Chemical resistance
7. Water resistance
✔✔Strain Gauge - ✔✔<1mm, contact, cheap, measure strain in material with high
elastic modulus in response to applied load
GF = (deltaR/R)/strain
✔✔Hall effect sensor - ✔✔1-2mm, non-contact, cheap, externally applied magnetic field
create Hall voltage, measure angular speed of wheels, application with very short rise-
time, proximity measurement
✔✔Mechanical switch - ✔✔few mm, contact, cheap, proximity sensing, fail-safe saftey,
safety guards, door position
✔✔Capacitive sensor - ✔✔1-5mm, non contact, expensive, external object alter the
capacitance of internal capacitor, detect non metallic object in human body, fill level for
bottle, user input in smartphone, proximity sensing
✔✔Inductive sensor - ✔✔1-5mm, non contact, expensive, requires metal object, detect
change in inductance, sensing proximity of metal object, measuring speed of spur gear
✔✔Linear resistive sensor - ✔✔<50cm, contact, cheap to expensive, short range linear
position, change resistance with distance
✔✔Ultrasonic sensor - ✔✔1cm-10m, non contact, expensive, tank level sensing,
parking sensor, presence of item of conveyor belt, hand held distance measuring device
✔✔Optical distance sensor (laser diode) - ✔✔few cm - several km, non contact,
expensive, light emitter and receiver, measure time or amount reflected back, automatic
door opening/closing, speed measurement, surveying, mapping
QUESTIONS AND SOLUTIONS RATED A+
✔✔Dead band - ✔✔range within which sensor cannot measured
✔✔Resolution - ✔✔smallest value that can be resolved (detected) by the sensor
✔✔Accuracy - ✔✔measure of how close the output value represent the actual value of
the physical quantity being sensed
✔✔level in n bit? - ✔✔2^n
✔✔Noise - ✔✔random variation of the output independent of the measured value
✔✔hystersis - ✔✔systematic error where the direction of change of measured value
affects the value. The output of a sensor is dependent on the time derivative of the
measured value.
✔✔non-linearity - ✔✔measure of systematic deviation from proportionality across the
range of the sensor.
✔✔(temporal) stability or drift - ✔✔measure of how much output value changes with
time independent of the the input value
✔✔thermal stability or drift - ✔✔measure of the systematic change in output value due
to change in temperature
✔✔Sensitivity - ✔✔relationship between the scale of the measured quantity and the
scale of the electrical output, given in (electrical unit)/(physical unit)
✔✔Temporal response - ✔✔ability of any sensor to measure a quantity that changes in
time is limited by its temporal response
✔✔Time constant
(Temporal response) - ✔✔measure of time taken for the out signal to reach a level
following a step change in inout
✔✔Settling time
(Temporal response) - ✔✔time taken for output value to reach 90% of its final value
✔✔Rise time
(Temporal response) - ✔✔time taken for the output to reach a certain value
✔✔Bandwidth
, (Temporal response) - ✔✔a frequency domain measure of the change in the sensor
amplitude response with frequency variation of the measured quantity.
✔✔Supply voltage/current - ✔✔electrical supply to work
✔✔Rated - ✔✔value use to test the sensor in order to determine the values of
parameters whilst the sensor is operational
✔✔Mechanical Parameters - ✔✔1. Physical Dimension
2. Mass
3. Mounting
4. Packaging style
5. Shock resistance
6. Chemical resistance
7. Water resistance
✔✔Strain Gauge - ✔✔<1mm, contact, cheap, measure strain in material with high
elastic modulus in response to applied load
GF = (deltaR/R)/strain
✔✔Hall effect sensor - ✔✔1-2mm, non-contact, cheap, externally applied magnetic field
create Hall voltage, measure angular speed of wheels, application with very short rise-
time, proximity measurement
✔✔Mechanical switch - ✔✔few mm, contact, cheap, proximity sensing, fail-safe saftey,
safety guards, door position
✔✔Capacitive sensor - ✔✔1-5mm, non contact, expensive, external object alter the
capacitance of internal capacitor, detect non metallic object in human body, fill level for
bottle, user input in smartphone, proximity sensing
✔✔Inductive sensor - ✔✔1-5mm, non contact, expensive, requires metal object, detect
change in inductance, sensing proximity of metal object, measuring speed of spur gear
✔✔Linear resistive sensor - ✔✔<50cm, contact, cheap to expensive, short range linear
position, change resistance with distance
✔✔Ultrasonic sensor - ✔✔1cm-10m, non contact, expensive, tank level sensing,
parking sensor, presence of item of conveyor belt, hand held distance measuring device
✔✔Optical distance sensor (laser diode) - ✔✔few cm - several km, non contact,
expensive, light emitter and receiver, measure time or amount reflected back, automatic
door opening/closing, speed measurement, surveying, mapping
