MECHATRONICS UPDATED EXAM
STUDY GUIDE QUESTIONS AND
SOLUTIONS RATED A.pdf
What are the advantages of level 3 systems integration? - answer-• Reduced load on
ECU•
Reduction in noise (interference) because signals are digital.
• Bus-compatible interface
• Multi-sensor design
• Corrections of sensor deviations at the measuring point, and storage in memory chips
• 3rd level allows DSP is digital signal processing. This important stage can be used to
pre-process the data for the information sought
• The sensor and signal processing can be combined in an ASIC, an application specific
integrated circuit.
What does 4th level systems integration have in addition to 3rd level. - answer-Ai at the
sensor (edge intelligence)
What does the transducer do? - answer-Converts measured energy into electrical
energy i.e a strain gauge which converts strain to resistance change which can be
detected as a voltage change.
What does the primary sensing element do? - answer-Receives energy from the
measured medium and produces an output which depends in some way on the
measurement.
What is a Passive Sensor? - answer-Passive Sensors are based on the passive circuit
components of R,C,L. Theses sensors all require a power supply, and are normally
used as part of an active bridge circuit to provide a voltage out (normally mV). They are
normally connected to an op amp to boost the mV to V, for input to an ADC.
What is an Active Sensor? - answer-Active Sensors, do not require a power supply.
Examples include thermocouples, electromagnetic effect and piezo electric effect
sensors.
What is an Optical Sensor? - answer-Optical sensors require a power supply for the
source and detector but not to the measured object.
What is the key output of the Signal Conditioning (SC) stage - answer-The key outcome
is that the voltage input to the A/D stage should be 10-12V, depending on the A/D at full
scale.
, Why is it advantageous to distribute automotive symbols in the digital format? - answer-
Analogue to Digital (A/D) the output of the ADC stage is digital and thus immune to
noise interference.
How do you calculate the resolution of a measurement? - answer-Divide the full scale
voltage by 2 to the power of the number of bits used to store the measurement.
e.g. for a 16 bit A to D conversions when the full scale voltage is 16 bits the resolution is
10/2^16 = 0.15mV
What is the difference between 1st, 2nd and 3rd level integration? - answer-1st level
integration is not Bus compatible and is resistant to interference (analogue)
2nd and 3rd level integration are both digital (immune to interference) and bus
compatible but 3rd level uses microcontrollers whereas 2nd uses bus interfaces.
What is the downside to using a displacement potentiometer to measure the movement
of a wiper. - answer-As the wiper moves the track will wear out over time causing the
sensor to eventually fail.
How does a displacement potentiometer work? - answer-By moving a wire along a
conductive track the varies the resistance which can be measured as a varying voltage.
(Voltage divider circuit)
How does a 3 plate capacitive displacement sensor work? and what are its
advantages? - answer-Change of capacitance between the plates is measured.
Capacitance can be changed by the area of plate overlap, distance between plates or
amount of dielectric between plates. Is advantageous as it does not require additional
devices for linearisation.
What is the equation for a voltage change of a 3 plate capacitive displacement sensor?
- answer-ΔV = Vs*x/d
where Vs is the voltage between the top and bottom plates, x is the distance moved by
the place and d is the initial distance between plates.
How does an electromagnetic tachometer work? (wheel sensor) - answer-A coil is
wrapped around a magnet with one end of the magnet placed in close proximity to a
wheel with teeth on it. When the wheel spins the teeth cause a variation in flux which
produces an EMF in the coil. This output is fairly sinusioidal with the peak to peak
values being proportional to the shaft speed. As shaft speed increases the frequency
and amplitude of the sensor signal also increase.
What are the advantages and disadvantages of an electromagnetic tachometer -
answer-Advantages:
Low cost
STUDY GUIDE QUESTIONS AND
SOLUTIONS RATED A.pdf
What are the advantages of level 3 systems integration? - answer-• Reduced load on
ECU•
Reduction in noise (interference) because signals are digital.
• Bus-compatible interface
• Multi-sensor design
• Corrections of sensor deviations at the measuring point, and storage in memory chips
• 3rd level allows DSP is digital signal processing. This important stage can be used to
pre-process the data for the information sought
• The sensor and signal processing can be combined in an ASIC, an application specific
integrated circuit.
What does 4th level systems integration have in addition to 3rd level. - answer-Ai at the
sensor (edge intelligence)
What does the transducer do? - answer-Converts measured energy into electrical
energy i.e a strain gauge which converts strain to resistance change which can be
detected as a voltage change.
What does the primary sensing element do? - answer-Receives energy from the
measured medium and produces an output which depends in some way on the
measurement.
What is a Passive Sensor? - answer-Passive Sensors are based on the passive circuit
components of R,C,L. Theses sensors all require a power supply, and are normally
used as part of an active bridge circuit to provide a voltage out (normally mV). They are
normally connected to an op amp to boost the mV to V, for input to an ADC.
What is an Active Sensor? - answer-Active Sensors, do not require a power supply.
Examples include thermocouples, electromagnetic effect and piezo electric effect
sensors.
What is an Optical Sensor? - answer-Optical sensors require a power supply for the
source and detector but not to the measured object.
What is the key output of the Signal Conditioning (SC) stage - answer-The key outcome
is that the voltage input to the A/D stage should be 10-12V, depending on the A/D at full
scale.
, Why is it advantageous to distribute automotive symbols in the digital format? - answer-
Analogue to Digital (A/D) the output of the ADC stage is digital and thus immune to
noise interference.
How do you calculate the resolution of a measurement? - answer-Divide the full scale
voltage by 2 to the power of the number of bits used to store the measurement.
e.g. for a 16 bit A to D conversions when the full scale voltage is 16 bits the resolution is
10/2^16 = 0.15mV
What is the difference between 1st, 2nd and 3rd level integration? - answer-1st level
integration is not Bus compatible and is resistant to interference (analogue)
2nd and 3rd level integration are both digital (immune to interference) and bus
compatible but 3rd level uses microcontrollers whereas 2nd uses bus interfaces.
What is the downside to using a displacement potentiometer to measure the movement
of a wiper. - answer-As the wiper moves the track will wear out over time causing the
sensor to eventually fail.
How does a displacement potentiometer work? - answer-By moving a wire along a
conductive track the varies the resistance which can be measured as a varying voltage.
(Voltage divider circuit)
How does a 3 plate capacitive displacement sensor work? and what are its
advantages? - answer-Change of capacitance between the plates is measured.
Capacitance can be changed by the area of plate overlap, distance between plates or
amount of dielectric between plates. Is advantageous as it does not require additional
devices for linearisation.
What is the equation for a voltage change of a 3 plate capacitive displacement sensor?
- answer-ΔV = Vs*x/d
where Vs is the voltage between the top and bottom plates, x is the distance moved by
the place and d is the initial distance between plates.
How does an electromagnetic tachometer work? (wheel sensor) - answer-A coil is
wrapped around a magnet with one end of the magnet placed in close proximity to a
wheel with teeth on it. When the wheel spins the teeth cause a variation in flux which
produces an EMF in the coil. This output is fairly sinusioidal with the peak to peak
values being proportional to the shaft speed. As shaft speed increases the frequency
and amplitude of the sensor signal also increase.
What are the advantages and disadvantages of an electromagnetic tachometer -
answer-Advantages:
Low cost
