Gergo Szakmany Automotive Sensors

7/31/2019 Gergo Szakmany Automotive Sensors

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Gergo Szakmany

EE87022


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Oilsensor

Oxygen

sensor

Fuel level

ccelerometer

Seat belt tension

Passenger Occupancy

Wheel speed

Tire pressure monitor

Anti thief sensors

Radar sensor

Rain sensor

Parking sensor

Indoor/outdoortemperaturesensors

GPS

Watercoolanttemper

ature

Tachometer

SpeedometerOdometer


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Oxygen sensor

Oil sensors

Fuel gauge Dip - stick


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Miniature voltage generatorCompare the exhaust O2 level and

outside air O2 level


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=

.

2

2ln

4exh

air

s

pO

pO

F

RTV


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High voltage: fuel mixture rich, little unburned oxigen

Low voltage: fuel mixture lean, excess oxygen


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On-board oil sensorsand oil analyzersinstalled Oil pressure:

Hydrostatic force per

unit area Age of the oil in theengine: dielectricconstant of the oil.Parallel platecapacitor separatedby oil. An oildielectric testercorrelates to theacidity of the oil andindicates the level ofoil degradation


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Inaccurate due to its mechanism, shape offuel tank

Gauge: resistance , current , bimetallic cools, straighten out, pull needle form fullto empty.

Newer car: resistor output into amicroprocessor compensate shape of tank

Damping needle movment up hill , down hill, turnFloat


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Speed

Wheel speed

Engine ignition

timingTahometer

Odometer


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Transmission and driveshaftrotate mandrel too permanent magnet rotate rotating magnetic field forceact on speed cup electricalcurretn flows (Eddy current) drag torque needle rotate

same direction as magnetic field

Transmission output rotatewith a toothed metal disk atthe end

Stationary detector covers amagnetic coil

Teeth move past the coilinterrupt the magnetic field

series of pulses sent tocomputer


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Percent error = 100x("standarddiameter"/"new diameter" - 1

For example, a standard tire is

"185/70R14" with diameter = 185x70/1270+ 14 = 24.196850 in. Another is"195/50R15" with 195x50/1270 + 15 =

22.677165 in. Replacing the first tire (andwheels) with the second (on 15" wheels), aspeedometer reads24.19../22.67..=1.0670139 times the

correct speed or 6.7% too high.


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For ABS one need to know the speed of eachwheel


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Modernaccelerometersbased on simplest

MEMS design Mass-damper-spring

Air bag deploymentsystem rapidnegativeacceleration

Electronic stability

control

Si

tether


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Two capacitatorconfiguration

Measure difference

between twocapacitance


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Based on total internal reflection LED or Infrared light source Photodiode Amplifier CPU wipers on, windows up


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Offset amplification raise thesensitivity of the sensor: nightdriving, high speed


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RF communication with on board computer


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Simplest form, it is nothing but one or more sensorsconnected to some sort ofsiren

Most modern car alarm systems: An array ofsensors that can include switches,

pressure sensors and motion detectors A siren, often able to create a variety of sounds sothat you can pick a distinct sound for your car

A radio receiver to allow wireless control from akey fob

An auxiliary battery so that the alarm canoperate even if the main battery getsdisconnected

A computer control unit that monitorseverything and sounds the alarm -- the "brain" of

the system


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In a closed-circuit system, the electric circuit is closed when the door isshut. This means that as long as the door is closed, electricity can flow fromone end of the circuit to the other. But if somebody opens the door, the circuitis opened, and electricity can't flow. This triggers an alarm.

In an open-circuit system, opening the door closes the circuit, so electricitybegins to flow. In this system, the alarm is triggered when the circuit iscompleted


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Breaking glass hasits own soundfrequency

Air pressure briefchange as dooropen, windowsbreak, even if the

inside outsidepressure is thesame


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Detects radar/lasersignals

Try to disturb the

reflected waves Emits jamming

signals

Warn the driver

Gergo Szakmany Automotive Sensors

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