The document discusses various computer controlled automotive systems. It describes the electronic control unit (ECU) as the "brain" that controls engine functions like fuel injection and ignition timing based on inputs from sensors. These sensors measure things like crankshaft position, throttle position, intake pressure, air temperature and more. The ECU uses algorithms to determine spark timing and fuel levels needed. Other computer controlled systems discussed include anti-lock braking systems, airbags, speedometers, odometers, tachometers and traction control.

1. Dept of IT, RVCE 1
AUTOMOTIVE COMPUTER
CONTROLLED SYSTEMS
FAISAL AMEEN ZAMAN(1RV09IT017)
SIDDHARTH D.C.(1RV09IT043)
SIVA SUBRAMANIAN(1RV09IT045)

2. WHY AUTOMOTIVE CONTROL
SYSTEMS?
2
 We see and use automobiles everyday, but
most of us are not aware of the logic hidden
underneath these systems.
 While purchasing a vehicle, it is important you
know the systems underneath to properly
evaluate a vehicle and know whether you‟re
being cheated or not.
 Over 50% of whoever is employed end up in the
automotive sector in someway or the other.
Dept of IT, RVCE

3. 2nd SEM BASIC MECHANICAL ENGINEERING- A
RECAP
3
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4. ECU
THE “BRAIN” BEHIND THE “HEART”
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 What is an ECU?
Any embedded system that controls one or more
electrical systems in a vehicle.
An ECU basically does 2 functions, „HOW MUCH
OF FUEL TO BURN‟ and „WHEN TO BURN IT‟.
 Besides these functions it also does other auxiliary
functions such as controlling the radiator fan, instrument
cluster and various safety systems (think ABS, Traction
Control, Airbags etc.).
Dept of IT, RVCE

5. THE ECU DEMYSTIFIED
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 How does the ECU does what it does?
The ECU determines the amount of fuel and ignition
timing by collecting information from various sensors which
convey the current operating status of the engine and
other auxiliary systems on the car.
 The sensors used as inputs for the ECU can be
classified into:-
• Position Sensors
• Physical Condition Sensors(Temperature, Pressure)
Dept of IT, RVCE

6. Sensors which tell when to burn the fuel
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• Crank Angle Sensor
Used to provide the position of the
Crankshaft.
By this, the sensor will indirectly tell the
ECU that the piston has almost reached
the top position and it is time for the
spark plug to provide the “spark”.
• Camshaft Position Sensor
Used to provide the position of the
camshaft
This sensor will tell the ECU that it the
intake valve will now open and it is now
time to spray the fuel and let the air-fuel
mixture inside the cylinder
Dept of IT, RVCE

7. Sensors which tell the Engine how
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much fuel to burn
 Throttle Position
Sensor
Nothing but a Rotary Potentiometer
(4th sem ITDC)
Depending upon how much the
accelerator is actuated, the throttle
plate is turned by a certain angle.
More the actuation, more the air
which enters, which means more
fuel to burn, hence more power
produced
Dept of IT, RVCE

8. ALTERNATIVE SENSORS WHICH TELL HOW
MUCH FUEL TO BURN
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 Intake Pressure Sensor
Is generally a piezoelectric sensor
Tells the suction pressure caused due to the suction
created by the combustion chamber
More the suction pressure means more air is sucked and
hence more fuel is needed, hence more power
 Air Mass Sensor
Provides an output proportional to the mass of air flowing
into the cylinder
More air means more fuel sprayed, hence, yet again,
greater power Dept of IT, RVCE

9. OTHER IMPORTANT SENSORS NEEDED FOR
THE RUNNING OF THE ENGINE
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 Engine Temperature Sensor
Is generally a thermocouple
Used to input the engine temperature to the ECU
High temperature indicate engine overheating, which the
ECU interprets and hence tells the radiator to start remove
the heat from the engine via the coolant.
 Air Temperature Sensor
Provides the temperature of the ambient air.
This is essential since the temperature of the air lets us
know about the density of the air which in turns lets us
know about the pressure of atmospheric air. Used along
with an Intake Pressure Sensor of IT, RVCE
Dept

10. SO WHAT DOES THE ECU DO
WITH ALL THESE INPUTS?
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 All the analog inputs are converted into digital
inputs via ADC‟s
 The ECU has prewritten algorithms into it‟s ROM
 This algorithm generates a value of spark timing,
amount and timing of fuel injection, and activates
the cooling system based on inputs from the
sensors.
 This value is converted to analog form via DAC‟s
and provided to the respective output lines in the
form of an analog voltage. of IT, RVCE
Dept

11. OTHER COMPUTER
CONTROLLED SYSTEMS
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 ABS
 Airbags
 Speedometer
 Odometer
 Tachometer
 Traction Control
 Battery Management in Hybrid Vehicles
Dept of IT, RVCE

12. SPEEDOMETER &
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ODOMETER
 A speedometer is an instrument cluster
which shows the driver how fast the
vehicle is moving.
 Inside the speedometer, the cable turns
shaft with a small magnet on it.
 The odometer records the total distance
the vehicle has traveled.
 The odometer operates by a pair of gears
from the speedometer.
Dept of IT, RVCE

13. Conti..
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 Some vehicles have an electronically-driven
speedometer and odometer.
 A vehicle speed sensor sends vehicle speed
signal through wiring to the speedometer. This
eliminates speedometer cable.
 The odometer reading is not lost when battery
is disconnected.
Dept of IT, RVCE

14. SPEED CONTROL
14 SYSTEM
 This helps the vehicle to automatically
maintain a speed selected by the driver.
 An actuator motor or vacuum servo opens and
closes the throttle, as and when needed, to
maintain the speed.
Dept of IT, RVCE

15. TACHOMETERS
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 They are used to indicate the RPM of the
engine. This is useful when the driver wants to
shift gears. An ideal RPM shift ensures the
engine is working in the optimal condition.(No
over-revving).
 Traditionally, tachometers are dials with a
needle pointing to the current speed in RPMs
(revolutions per minute). However, with the
onset of new reading systems, the use of digital
tachometers has risen sharply
Dept of IT, RVCE

16. Major parts of tachometer
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 Dial :
 The dial tells the driver the tachometer's
reading. In a car, it is located on the dashboard.
 The device is necessary in order to regulate
how hard the engine is being worked.
 Generators :
 Engines with ignition systems usually utilize a
small generator attached to the engine drive
shaft. In this case, the tachometer is actually a
voltage meter, meaning that it counts the
pulsations of voltage in the ignition system.
 The output voltage is proportional to the shaft's
speed so measuring voltage is converted into
an accurate measurement in RPMs.
Dept of IT, RVCE

17. ABS-ANTI-LOCK BRAKE
CONTROLLER
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 Most ABS works on PASCAL‟s law
 A typical ABS includes a central electronic
control unit (ECU), wheel speed sensors,
and at least one hydraulic actuator.
 There is one speed sensor mounted on
each wheel.
 This sensors supply the speed of each
wheel to the microcontroller, and this MC
calculates the braking force to be applied on
each wheel.
 This ensures that Dept of tires do not skid due
the IT, RVCE

18. ABS >>
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 Some anti-lock system can apply or release
braking pressure 16 times per second
 The ABS equipment may also be used to
implement a traction control system(TCS) on
acceleration of the vehicle
Dept of IT, RVCE

19. Air bag
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 There are two types - frontal and the
various types of side-impact airbags.
 There are four crash sensors deployed for
its working
 The system is powered by the battery of
car
 Propellant used in airbag is sodium azide
 The deployment time from impact to
inflation is about 50Dept of IT, RVCE
ms

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23. Traction control
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 Designed to prevent loss of traction(Grip) of driven
road wheels
 Reduces or suppress spark sequence to one or more
cylinders(shuts of some cylinders temporarily)
 Reduce fuel supply to one or more cylinders
 Brake force applied at one or more wheels
 Electronic throttle control system serves as a
mechanical link between the accelerator pedal and
the throttle In turbo-charged vehicles,
 A boost control solenoid can be actuated to reduce
boost and therefore engine power.
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28. HYBRID CARS
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 A car which combines a internal
combustion engine propulsion system with
an electric propulsion system.
Dept of IT, RVCE

29. Components
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 Conventional car engine – It can be a petrol or diesel
engine. They will be smaller with greater efficiency and
lesser emissions.
 Fuel Tank – For storing the fuel needed to run the car‟s
IC engine.
 Batteries – Batteries are needed to store and release
energy as required by the car. The energy from the
battery is taken by the motor.
 Electric Motor and generator – Though motors can act
as generators, both of them are needed for this car. A
motor will be needed to take energy from the batteries
and accelerate the car. Generators, on the other hand,
are needed to produce theDept of IT, RVCE power.
electrical

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Advantages
 Better mileage.
 More reliable and comfortable.
 Very clean cars due to less emissions.
 Batteries need not be charged by an external source
Disadvantages
 The initial cost will be very high – higher than other cars.
 Spare parts will be very costly and rare.
 The Hybrid car battery also has a limited life span
 As there is electrical components there is a risk of shock
during an accident
Dept of IT, RVCE

32. Famous Hybrid Cars
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Ford Escape Hybrid Toyota Prius
Dept of IT, RVCE