Unit 1

Automotive systems, design cycle

and automotive industry overview
Text book:
“Understanding Automotive Electronics”
by William B. Ribbens

https://drive.google.com/file/d/1O-LxVXOYL1I40AeFqWtMzmNb86ph-uLF/view?usp=sharing
 Automotive industry(AI) overview

 Automotive sector in India is valued at $93billion currently and is growing

at a steady pace.
 The AI contributes a great 49% of India’s manufacturing GDP.
 It consists of manufacturing companies whose primary activity is

 Development

 Manufacturing

 Distribution

 Service of transportation vehicles

and vehicle components for business and consumer
markets
 Evolution of Automotive Electronics
 The dawn of automotive electronics came in the early 1970s,when the only electronics in a car
were the radio, the alternator(diodes) and the voltage regulator that controlled the alternator.
The last 30 years have seen rapid technological innovations in automotive electronics, driven
primarily by advancement in semiconductors and related software that controls the systems

 Two major events brought the trend towards the use of modern electronics in the automobile
 The introduction of govt. regulations for exhaust emissions and fuel economy, which required better control of
the engine than was possible with the methods being used
 The development of relatively relatively low cost per function solid state digital that could be used for engine
control and other applications

 Some of the present and potential applications in automobile industry are

 Electronic engine control for minimizing exhaust emissions and maximizing fuel economy
 Instrumentation for measuring vehicle performance parameters and for diagnosis of on board system
malfunctions
 Vehicle motion control
 Safety and convenience
 Entertainment/communication/navigation
 How a Car Engine Works - YouTube

How Do Electric Vehicles Work? - YouTube

Here's Why Toyota's New Hydrogen Car is the

Future (Goodbye Tesla) - YouTube
 Systems of the automobile
 The important automotive systems includes the following
 Engine
 drivetrain
 Suspension
 Steering
 Brakes
 Instrumentation
 Electrical/electronics
 Motion control
 Safety
 Comfort/convenience
 Entertainment/communication/navigation

 The frame or chassis on which the body is mounted is supported by the suspension system
 The brakes are connected to the opposite end of the suspension components
 The steering and other major mechanical systems are mounted on one of these components
 Engines
 The engine is an automobile provides all the power of moving the automobile, for the hydraulic
and pneumatic systems, and for the electrical systems.
 The most used engine types are:
 4 stroke/cycle
 Gasoline fueled
 Spark ignited
The major components of the engine include the following
 Engine block
 Cylinder
 Crankshaft
 Pistons
 Connecting rods
 Camshaft
 Cylinder head
 Valves
 Fuel control system
 Exhaust system
 Cooling system
 Electrical system
 Engines
 Electronics play a direct role in all aspects of controlling engine operation, including the
fuel and air flow control, ignition, exhaust and evaporative emission system, and
diagnostic and maintenance operations
 Mechanical rotary power is produced in an engine

through the combustion of gasoline inside cylinders

in the engine block and a mechanism consisting
of pistons and a linkage coupled to the crankshaft.
 The cylinders are cast in the engine block

And pistons fit tightly into the cylinder and

have rings that provide a tight siding seal
against the cylinder wall.
 The pistons are connected to the crankshaft by

connecting rods. The crankshaft converts the up

and down motion of the pistons to the rotary
Motion and the torque needed to drive the wheels
 Cylinder head
 The cylinder head contains an intake and exhaust valve for each cylinder.
When both valves are closed the head seals the top of the cylinder while the
piston rings seal the bottom of the cylinder.
 During the combustion, high pressure is developed in the cylinder which in
turn, produces a force on the piston that creates the torque on the crankshaft
 Engines
 The valves are operated by off-center cams on
the camshaft, which is driven by the crankshaft as shown in pic.
 The camshaft rotates at exactly half the crankshaft
speed because a complete cycle of any cylinder involves
two complete crankshaft rotation and only one sequence
of opening and closing of the associated intake
and exhaust valves
 The valves are normally held closed by powerful springs. When the time comes
for a valve to open the lobe on the cam forces the
pushrod upward against one end of the rocker arm
the other end of the rocker arm moves downward
and forces the valve open
 Four stroke cycle
 one complete cycle in the 4-stroke engine
requires two complete rotations of the
crankshaft
 As the crankshaft rotates, the piston moves
up and down in the cylinder
 Two complete revolutions of the crankshaft
make up one cycle, includes 4 strokes, they
are:
 Intake
 Compression
 Power
 Exhaust

 Intake: the piston is moving from top to bottom and intake valve is open, creating a
partial vacuum, which draws a mixture of air and vaporized gasoline into the cylinder.
The intake valve Is closed after the piston reaches the bottom. This position is called as
bottom dead center(BDC)
 Four stroke cycle
 Compression:
 Both valves are closed, the piston moves upward and
compress the fuel and air mixture against the cylinder head.
 When the piston reaches the top of this stroke the ignition
system produces an electrical spark at the tip of the spark
plug(top of the center-TDC)
 The spark ignites the air-fuel mixture, causing rapid rise in
the pressure in the cylinder

 Power:
 The high pressure created by the burning the burning
mixture forces the piston downward, which in turn
creates a force on the piston resulting in the torque
on the crankshaft
 The actual usable power is generated in this stroke

 Exhaust:
 Piston moves upward, exhaust valve is open and the piston forces the
burned gases from the cylinder through the exhaust port into the exhaust
system and out the tailpipe into the atmosphere
 Four stroke cycle
 The cycle repeats continuously .
 In a single cylinder engine power is produced only during
the power stroke which is only one quarter of the cycle,
thus modern engines have multiple cylinders, each of
which contributes power during its associated power
stroke
https://youtu.be/7rI2H8D0s1I
 Ignition system
 To produce power an electric spark is produced across the gap between a
pair of electrodes of a park plug which produces sufficient energy to cause
combustion of fuel and air mixture called as ignition
 The spark must persist for for a period of about a ms.
 This short period makes ignition possible using highly efficient pulse
transformer circuits in which a circuit having a relatively low average
current can deliver a very high voltage pulse to the spark plug
 The ignition system consists of several components
 spark plug
 Pulse transformers
 Timing control circuitry
 Distribution apparatus
 Spark plug
 The spark is produced by applying a high-voltage pulse of from 20kV to 40kV
between the center electrode and ground.
 The actual voltage required to start the arc varies with the size of the gap, the
compression ratio, air-fuel ratio
 Spark plug configuration is shown in fig, which

consists a pair of electrodes, called Center and

ground electrodes, separated by a gap.
 It can be 0.6mm or 1mm Specified for each

engine.

 The center electrode is insulated from the

ground electrode and the metallic shell assembly.
 The ground electrode is at electrical ground

Potential because one terminal of the battery that supplies the current to generate high
voltage pulse is connected to the engine block and frame
 High voltage circuit and distribution
 The ignition system provides the high voltage pulse to initiate the arc.
 The high voltage pulse is generated by inductive discharge of special high
voltage transformer called an ignition coil, which is then delivered to the
appropriate spark plug at the correct time by a distribution circuit
 Spark pulse generation
 Generation of the high-voltage pulse accomplished by switching the current through
the primary circuit .
 Achieved by opening and closing the
breaker points by a rotary cam in the
distributor.
 During the intervals between the
ignition pulses, the breaker points are closed
(known as dwell).
 Current flows through the primary of the coil
 and a magnetic field is created that links the
primary and secondary of the coil
 Spark pulse generation
 Whenever the spark pulse is required, the breaker points are opened, which interrupts the flow of current in
the primary of the coil resulting in the collapsing of magnetic field.
 Which induces the high voltage pulse in the secondary of the coil. this pulse is routed through the
distributor rotor, the terminal in the distributor cap, and the spark plug wire to the appropriate spark plug.
 the waveform of the primary current is shown in fig
 The primary current increases with time after the points are closed(a)
 At the instant the points open, this current begins to fall rapidly
 It is during this rapid drop in primary current that the secondary high-voltage pulse occurs (point b). The
primary current oscillates (the “wavy’’ portion; point c) because of the resonant circuit formed between the
coil and capacitor
 Spark pulse generation
 The mechanism for opening and closing the breaker points of a conventional distributor is illustrated in fig
 A cam having a number of lobes equal to the number of cylinders is mounted on the distributor shaft. As
this cam rotates, it alternately opens and closes the breaker points.
 When the rubbing block is aligned with a flat surface on the cam, the points are closed (i.e., dwell period),
as shown in Figure 1.12a. As the cam rotates, the rubbing block is moved by the lobe (high point) on the
cam as shown in Figure 1.12b. At this time, the breaker points open (corresponding to point b of Figure
1.11) and spark occurs.
 The rotary switch is connected to the same shaft as the cam, thereby synchronizing the actions of spark
creation with the switching of the high-voltage pulse to each spark plug. The distributor shaft is coupled to
the camshaft and rotates at the same speed and is positioned relative to the camshaft so that the spark occurs
at the correct time during each engine cycle to produce optimum combustion is known as “ignition timing.”
 Ignition Timing
 Ignition occurs some time before top dead center (BTDC)
during the compression stroke of the piston. This time is
measured in degrees of crankshaft rotation BTDC. For a modern
SI engine, this timing is typically 8 to 10 degrees for the basic
mechanical setting with the engine running at low speed (low
rpm). This basic timing is set by the design of the mechanical
coupling between the crankshaft and the distributor
 As the engine speed increases, the angle through which the
crankshaft rotates in the time required to burn the fuel and air
mixture increases. For this reason, the spark must occur at a
larger angle BTDC for higher engine speeds. This change in
ignition timing is called spark advance. In a conventional
ignition system, the mechanism for this is called a centrifugal
spark advance
 .As engine speed increases, the distributor shaft rotates faster,
and the weights are thrown outward by centrifugal force. The
weights operate through a mechanical lever, so their movement
causes a change in the relative angular position between the
rubbing block on the breaker points and the distributor cam, and
advances the time when the lobe opens the points
 Ignition Timing
 In addition, the ignition timing needs to be adjusted as a
function of intake manifold pressure. Whenever the throttle is
nearly closed, the manifold pressure is low (i.e., nearly a
vacuum). The combustion time for the air–fuel mixture is longer
for low manifold pressure conditions than for high manifold
pressure conditions (i.e., near atmospheric pressure). As a result,
the spark timing must be advanced for low pressure

 Breaker Point Operation conditions to maintain maximum

power and fuel economy, done by vacuum advance mechanism
that has a flexible diaphragm connected through a rod to the
plate on which the breaker points are mounted. One side of the
diaphragm is open to atmospheric pressure; the other side is
connected through a hose to manifold vacuum. As manifold
vacuum increases, the diaphragm is deflected (atmospheric
pressure pushes it) and moves the breaker point plate to advance
the timing.

 Ignition timing significantly affects engine performance and

exhaust emissions; therefore, it is one of the major factors that is
electronically controlled in the modern SI engine.
 Automotive transmissions
 The engine drivetrain system of the automobile consists of the engine,
transmission, drive shaft, differential, and driven wheels
 Transmission:
 Comprises of a gear system that adjusts the ratio of engine speed to wheel
speed.
 transmission enables the engine to operate within its optimal performance
range regardless of the vehicle load or speed.
 provides a gear ratio between the engine speed and vehicle speed such that
the engine provides adequate power to drive the vehicle at any speed.
 To accomplish this with a manual transmission, the driver selects the
correct gear ratio from a set of possible gear ratios (usually three to five for
passenger cars). An automatic transmission selects this gear ratio by means
of an automatic control system
 Transmission
 The configuration for an automatic transmission
consists of a fluid coupling mechanism(torque
converter)and a system of planetary gear sets. The
torque converter is formed from a pair of structures of
a semitoroidal shape
 There are two semitoroids, one of the toroids is driven
by the engine by the input shaft. The other semitoroid
is connected to the planetary gear system.
 These are fixed to the frame called as reactor. The
entire structure is mounted in a fluid tight chamber
and is filled with a hydraulic fluid. As the pump is
rotated by the engine, the hydraulic fluid circulates
 The fluid impinges on the turbine blades, imparting a
torque to it. The torque converter transmit engine
torque and power to the turbine from the engine.
 Transmission
 Gear System:
The planetary gear system consists of a set of three types of gears connected
together
 The inner gear is known as the sun gear. There are three gears meshed with the
sun gear at equal angles, which are known as planetary gears.
 These three gears are tied together with a cage that supports their axles. The third
gear, known as a ring gear, is a section of a cylinder with the gear teeth on the
inside. The ring gear meshes with the three planetary gears.
 In operation, one or more of these gear systems are held fixed to the transmission
housing via a set of hydraulically actuated clutches.
 For example, if the ring gear is held fixed and input power (torque) is applied to
the sun gear, the planetary gears rotate in the same direction as the sun gear but at
a reduced rate and at an increased torque.
 If the planetary gear cage is fixed, then the sun gear drives the ring gear in the
opposite direction as is done when the transmission is in reverse.
 If all three sets of gears are held fixed to each other rather than the transmission
housing, then direct drive (gear ratio = 1) is achieved.
 A typical automatic transmission has a cascade connection of a number of
planetary gear systems, each with its own set of hydraulically actuated clutches.

https://youtu.be/Y1zbE21Pzl0
 Transmission
 Earlier automatic transmissions have been controlled by a hydraulic and pneumatic
system, but the industry is moving toward electronic controls .
 The control system must determine the correct gear ratio by sensing the driver-
selected command, accelerator pedal position, and engine load.
 The proper gear ratio is actually computed in the electronic transmission control
system.
https://youtu.be/93okpZJMQYw
 Transmission
 DriveShaft:
The drive shaft is used on front-engine, rear wheel drive vehicles to couple
the transmission output shaft to the differential input shaft.
 Flexible couplings, called universal joints, allow the rear axle housing and
wheels to move up and down while the transmission remains stationary.
 In front wheel drive automobiles, a pair of drive shafts couples the
transmission to the drive wheels through flexible joints known as constant
velocity (CV) joints
 Transmission
 Differential:
 The differential serves three purposes :
 Transfer of the rotary motion of the drive shaft to
the wheels.
 The second purpose is to allow each driven
wheel to turn at a different speed. This is
necessary because the “outside” wheel must turn
faster than the “inside’’ wheel when the vehicle is
turning a corner.
 The third purpose is the torque increase provided
by the gear ratio.
 The gear ratio also affects fuel economy. In front
wheel drive cars, the transmission differential
and drive shafts are known collectively as the
transaxle assembly
 Vehicle breaking fundamentals
 Brakes are as basic to the automobile as the engine drivetrain system
and are responsible for slowing and stopping the vehicle. Most of the
kinetic energy of the car is dissipated by the brakes during deceleration
and stopping.
https://youtu.be/viUb-7eZZ0Y
 There are two major types of automotive brakes: drum and disk brakes.
Drum brakes are an extension of the types of brakes used on early cars.
Increasingly, automobile manufacturers are using disk brakes.
 Disk brakes are illustrated. A flat disk is attached to each wheel and
rotates with it as the car moves. A wheel cylinder assembly is connected
to the axle assembly. A pair of pistons having brake pad material are
mounted in the caliper assembly and are close to the disk.
 Under normal driving conditions, the pads are not in contact with the
disk, and the disk is free to rotate. When the brake pedal is depressed
hydraulic pressure is applied through the brake fluid to force the brake
pads against the disk.
 The braking force that decelerates the car results from friction between
the disk and the pads.
https://youtu.be/EQDapzl0N2Y
 Steering System
 A steering system is one of the major automotive subsystems
required for operation of the car. It provides the driver control of
the path of the car over the ground.
 Steering functions by rotating the plane of the front wheels in the
desired direction of the turn. The angle between the front wheel
plane and the longitudinal axis of the car is known as the steering
angle. This angle is proportional to the rotation angle of the
steering wheel.
 Traditionally, automotive steering systems have consisted solely
of mechanical means for rotating the wheels about a nominally
vertical axis in response to rotation of the steering wheel.
 The inclination of this axis gives rise to a restoring torque that
tends to return the wheels to planes that are parallel to the
vehicle’s longitudinal axis so that the car will tend to travel
straight ahead.
 This restoring torque provides a steering stability for the car.
When steering the car, the driver must provide sufficient torque to
overcome the restoring torque. Because the restoring torque is
proportional to the vehicle weight for any given steering angle, https://youtu.be/uTqU35K_8AU
considerable driver effort is required for large cars, particularly at low
speeds and when parking.
 Steering System
 Rack and pinion steering is fast becoming the most common type
of steering in cars, small trucks. The rack and pinion set is
enclosed in a metals tube, with each end of the racks protruding
from the tube.
 A tie rod is attached to each end of the rack. Rack & pinion is a
type of steering with a pair of gears that convert rotary motion
into linear motion. These systems consist of a circular gear called
a pinion with teeth attached to a linear gear shaft called a rack.
 The rotary motions applied to the pinions cause it to turn while
moving the rack sideways. The mechanisms consist of pinions at
the end of the steering columns that coincide with the rack. The
pinion is attached to the steering column at its end.
 In this steering mechanism, the rack serves as the center section
of the three-piece rod. The rack has balls joints at each end that
allow for up and down movement of the wheels. Plus, there’s a
spring-loaded pad under the rack that minimizes backlash
between gears.
 In addition, ball joints further connect to the stub axle via ‘tie
rods.’ rotary motion of the steering wheel directly conveys the
wheels through the sideways motion of the rack. 
 Steering System
 In order to overcome this effort in relatively large cars, a power steering system is added. This
system consists of an engine-driven hydraulic pump, a hydraulic actuator, and control valve.
 Whenever the steering wheel is turned, a proportioning valve opens, allowing hydraulic
pressure to activate the actuator. The high-pressure hydraulic fluid pushes on one side of the
piston.
 The piston, in turn, is connected to the steering linkage and provides mechanical torque to
assist the driver in turning. This hydraulic force is often called steering boost. The desired
boost varies with vehicle speed.

 This graph shows that the available boost from the pump
increases with engine speed (or vehicle speed), whereas the
desired boost decreases with increasing speed
 Power steering system
 The hydraulic power steering system is a closed loop system that uses pressurized hydraulic
fluids for changing the wheel angle of front wheels based on steering angle. It contains a
hydraulic pump driven by a belt, valves, cylinder, reservoir and a driver control
mechanism(rack & pinion/steering gearboxes).
 When the driver rotates the steering wheel, the belt and pulley arrangement of the engine will
pull fluid from the reservoir to pump. The hydraulic pump will pressurize this fluid and will
release it through hydraulic fluid lines towards the rack. The rack has a piston and cylinder
arrangement. The cylinder has two openings on either side of the piston and the openings are
connected with the hydraulic fluid lines. When the high-pressure fluid is fed to any of the
openings, the piston will move towards the opposite direction along with the rack. This will
generate a smooth and precise linear motion of the front wheels.
https://youtu.be/eudfJPHf7DE
 Power steering system
 EPS eliminates many HPS components such as the pump,
hoses, fluid, drive belt, and pulley. For this reason, electric
steering systems tend to be smaller and lighter than hydraulic
systems.

 EPS systems have variable power assist, which provides

more assistance at lower vehicle speeds and less assistance at
higher speeds. They do not require any significant power to
operate when no steering assistance is required. For this
reason, they are more energy efficient than hydraulic systems.

 The EPS electronic control unit (ECU) calculates the

assisting power needed based on the torque being applied to
the steering wheel by the driver, the steering wheel position
and the vehicle’s speed.

 The EPS motor rotates a steering gear with an applied force

that reduces the torque required from the driver.
 Power steering system
 Unlike a hydraulic power steering system that continuously
drives a hydraulic pump, the efficiency advantage of an EPS
system is that it powers the EPS motor only when necessary.

 This results in reduced vehicle fuel consumption compared to

the same vehicle with an HPS system. These systems can be
tuned by simply modifying the software controlling the ECU

 An additional advantage of EPS is its ability to compensate for

one-sided forces such as a flat tire. It is also capable of steering in
emergency maneuvers in conjunction with the electronic stability
control.

 In current-day systems, there is always a mechanical connection

between the steering wheel and the steering gear. For safety
reasons, it is important that a failure in the electronics never
result in a situation where the motor prevents the driver from
steering the vehicle. EPS systems incorporate fail-safe
https://youtu.be/JePWZ9NxCrk
mechanisms that disconnect power from the motor in the event
that a problem with the ECU is detected.
 Overview of hybrid vehicles
 A hybrid combines at least one electric motor with a gasoline engine to move the car, and its system recaptures energy via regenerative
braking. Sometimes the electric motor does all the work, sometimes it's the gas engine, and sometimes they work together. The result is
less gasoline burned and, therefore, better fuel economy. Adding electric power can even boost performance in certain instances.
 In the early years following the introduction of cars with 42-volt electrical systems, there will be two separate electrical buses, one at 14
volts and the other at 42 volts. The 14-volt bus will be tied to a single 12-volt (nominal) battery. The 42-volt electrical bus will be tied
to three 12-volt batteries connected in series. The 14-volt bus will supply power to those components and subsystems that are found in
present-day vehicles including, for example, all lighting systems and electronic control systems. The 42-volt bus will be associated with
the electric drive system of the hybrid car where it can provide more efficient propulsion than would be possible with a 14-volt system.
 With all of them, electricity comes from a high-voltage battery pack (separate from the car's conventional 12-volt battery) that's
replenished by capturing energy from deceleration that's typically lost to heat generated by the brakes in conventional cars. (This
happens through the regenerative braking system.)
 The hybrid vehicle is capable of operation in three modes in which power comes from: (a) the engine only; (b) the electric motor only;
and (c) the combined engine and electric motor. In achieving these modes of operation, the engine and electric motor must be coupled
to the drivetrain. The two major types of coupling methods are known as a series or parallel hybrid electric car.
 Parallel Mode:
 In this most common design, the electric motor(s) and gasoline engine are connected in a common transmission that blends the two
power sources. That transmission can be an automatic, a manual, or a continuously variable transmission (CVT)
 Series Mode:
 In this design, the electric motor(s) provides all the thrust, and there is never a physical mechanical connection between the engine and
the wheels. The gasoline engine is just there to recharge the battery. This results in a driving experience that's more indicative of an
electric car, with smoother, powerful acceleration.
 Overview of hybrid vehicles
 Under mode (a), the motor rotates freely and neither produces nor absorbs any power.
 In modes (b) and (c), the motor receives electric power from an electronic control system and delivers the
required power to the drivetrain.
 The power to move the vehicle can come from the engine alone, from the battery via electric power to the
motor/generator or by both acting together. The motor generator/rotor is connected on the shaft between the
crankshaft and the transaxle assembly. The engine is connected to the transaxle by a mechanism that permits
the modes of operation.
 This mechanism is denoted C and can be one of many possible devices. In some configurations, it is an
electrically activated clutch that disconnects the engine from the transaxle when it is switched off for
electric propulsion but connects the engine to the transaxle for engine-only power or for combined engine
electric motor operation.
 In other vehicles, the engine and motor are coupled to the drivetrain via a power-splitting device capable of
controlling the power split between IC engine and electric motor. In a typical hybrid vehicle, the relative
power from the IC engine and the electric motor is adjusted to give optimum performance during normal
driving. In those exhaust emission-sensitive geographic areas, the vehicle can be powered solely by the
electric propulsion. The distribution of power as well as the generation of power for both systems are
electronically controlled.
 ECU Design Cycle
 In the Automotive industry, the term ECU often refers to an Engine Control Unit (ECU), or an Engine
Control Module (ECM). If this unit controls both an engine and a transmission, it is often described as a 
Powertrain Control Module (PCM).
 Fundamentally, the engine ECU controls the injection of the fuel and, in petrol engines, the timing of the
spark to ignite it. It determines the position of the engine’s internals using a Crankshaft Position Sensor so
that the injectors and ignition system are activated at precisely the correct time.  
 An internal combustion engine is essentially a big air pump that powers itself using fuel. As the air is
sucked in, enough fuel has to be provided to create power to sustain the engine’s operation while having a
useful amount left over to propel the car when required. This combination of air and fuel is called a
‘mixture’. Too much mixture and the engine will be full throttle, too little and the engine will not be able to
power itself or the car.
 Not only is the amount of mixture important, but the ratio of that mixture has to be correct. Too much fuel -
too little oxygen, and the combustion is dirty and wasteful. Too little fuel - too much oxygen makes the
combustion slow and weak.
 Engines used to have this mixture quantity and ratio controlled by an entirely mechanical metering device
called a carburetor, which was little more than a collection of fixed diameter holes (jets) through which the
engine ‘sucked’ the fuel. With the demands of modern vehicles focusing on fuel efficiency and lower
emissions, the mixture must be more tightly controlled.
 The only way to meet these strict requirements is to hand over control of the engine to an ECU, the Engine
Control Unit. The ECU has the job of controlling the fuel injection, ignition and ancillaries of the engine
using digitally stored equations and numeric tables, rather than by analogue means
Main Features of ECUs in a Vehicle

 Systematic transfer of data

 Dependability and Security
 Efficient data network
 Diagnostics
 Assistance in real-time decision making
 Improved quality of service
V- model development cycle
 ECU
 At the beginning of a new project, the overall system specifications are collected. These requirements are
analyzed and the core functions and features of each subsystem are specified. Control algorithms are
primarily designed in response to the pre-defined specifications, and they are also made robust with respect
to extreme and abnormal operating conditions. A modeling work of both the physical plant and the control
system occurs in this stage.
 Core Process for Electronic Systems and Software Development:
 The referenced development process model may be visualized in the form of the letter “V”.
 An adapted V-Model provides for the representation of the project phases and interfaces between system and
software development.
 The logical system architecture is the basis for the specification of the actual technical system architecture
 The analysis of technical implementation alternatives is based on a unified logical system architecture and is
supported by a variety of methods of the participating engineering disciplines
 The technical system architecture also includes a definition of all functions or sub functions that will be
implemented by means of software, also called software requirements.
 The software requirements thus defined are analyzed in the next step
 the software architecture is specified , that is, the software system boundaries and interfaces are defined, with
software components, software layers, and operating modes
 This step is followed by the specification of software components
 The procedure initially assumes an “ideal-world” environment. This means that this step ignores any
implementation details, such as the implementation in integer arithmetic
 ECU
 Design, Implementation, and Tests of Software Components:
 In the design phase, the previously ignored real-world aspects are subject to
scrutiny. At this point, all details affecting the implementation must be
defined.
 The resulting design decisions govern the implementation of software
components. At the end of this step, software components are tested
 Integration of Software Components and Software Integration Tests:
 When the development of the software components is completed—
frequently done by applying the principle of division of labor—and
components have passed the subsequent tests, integration can begin
 After integration of the components into a software system, a software
integration test concludes this step
 ECU
 Calibration:
 The calibration of the ECU software functions comprises
their parameterization
 Parameter settings may be supplied by the software in the
form of characteristic values, characteristic curves, and
characteristic maps
 System Test and Acceptance Test:
 A system test focusing on the logical system architecture
can be performed, with an acceptance test that
concentrates on user requirements
 Different Types of ECU
 ECM – Engine Control module

 EBCM – Electronic Brake control module

 PCM – Powertrain control module

 VCM – Vehicle control module

 BCM – Body control module Electronic/engine control module

 TCM-Transmission control module

 CCM- Central control module

 SCM- Suspension control module

 ACU- Airbag Control Unit

 TPM-Tire Pressure Monitoring System

Components of ECU
Assignment of ECUs to vehicle Sub
Systems
Example of ECU