The document provides an overview of various vehicle control systems, including antilock braking systems (ABS), traction control systems (TCS), electronic stability programs (ESP), active suspensions, all-wheel drive (AWD), drive-by-wire technologies, active noise and vibration control, cruise control, adaptive cruise control, stop-and-go functions, collision avoidance assists, overtaking warnings, and lane departure warnings. It describes the components and operation of these systems, which use sensors, electronic control units, actuators and other technologies to improve vehicle stability, handling, safety and driver assistance.

1. Vehicle Control SystemsVehicle Control Systems
An Overview of
Behzad Samadi
Department of Electrical Engineering
Amirkabir University of Technology

2. Vehicle Control Systems
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Vehicle Control SystemsVehicle Control Systems
 ABS
 TCS
 ESP
 4WS
 EPS
 Active Suspension
 AWD
 Drive by Wire
 ANC
 AEM
 ACC
 S&G
 ACA
 OW
 LW
 A/F Ratio Control
 Knock Control
 Idle Speed Control
 Variable Compression
Engine
 VVT
 ATC
 CVT

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Antilock Braking System (ABS)Antilock Braking System (ABS)
1. Reduce stopping
distance.
2. Maintain
steerability.
3. Maintain lateral
stability.

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The Operation of ABSThe Operation of ABS
 Minimize stopping distance.
 Maximize tire-road adhesion with wheel slip
control.

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The Operation of ABSThe Operation of ABS

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ABS ComponentsABS Components
 Wheel speed sensors.
 Electronic control unit.
 Hydraulic modulator.

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Wheel Speed SensorWheel Speed Sensor
Construction
 Magnetic core with
surrounding coil.
Operation
 Magnetic field changes
as toothed gear wheel
rotates.
 AC signal frequency
depends on wheel speed.
 ECU senses signal and
converts it to a square
wave.

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ABS in Action!ABS in Action!

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Traction Control System (TCS)Traction Control System (TCS)
 Traction control prevents a vehicle's
wheels from spinning excessively while on
slippery surfaces.
 Traction control is intended as a driver aid
which allows a vehicle to make better use
of available traction on slippery surfaces.
 It shares many of the mechanical and
electronic elements of the ABS.

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How TCS Works?How TCS Works?
Depending on the type of traction control
system fitted to the vehicle, wheel spin is
controlled by one or a combination of the
following:
 Brake application at one or more wheels.
 Closing the throttle.
 Retarding the spark.
 Fuel cutout.
 Leaner air/fuel ratio.

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TCS in Action!TCS in Action!

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Electronic Stability ProgramElectronic Stability Program
 The electronic stability
program helps improve
cornering and control. By
monitoring the slip at the
wheels as well as the driver's
steering and braking inputs,
ESP can sense differences
between the driver's intentions
and the vehicle's direction in
turns.

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ESP PerformanceESP Performance

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ESP OperationESP Operation

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ESP OperationESP Operation

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ESP ComponentsESP Components
A) active wheel speed
sensors
B) steering angle sensor
C) combined yaw rate
sensor/lateral
accelerometer
D) attached electronic
control unit (ECU)
E) motor
F) pressure sensor
G) hydraulic unit

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ESP ComponentsESP Components

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Automakers & Stability ControlAutomakers & Stability Control
 Audi: electronic stability program (ESP).
 BMW: dynamic stability control (DSC).
 DaimlerChrysler: electronic stability program (ESP).
 Ford motor company: advance Trac.
 General motors: active handling system (corvette), precision
control system (Oldsmobile), Stabilitrak (Pontiac, Buick,
Cadillac).
 Jaguar: dynamic stability control (DSC).
 Lexus: vehicle skid control (VSC)
 Porsche: Porsche stability management (PSM).
 Volkswagen: electronic stability program (ESP).
 Volvo: dynamic stability traction control (DSTC).

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ESP in Action!ESP in Action!

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Four Wheel SteerFour Wheel Steer
 Improve low-speed
maneuverability.
 Smallest possible
turn radius.
 Improved handling
at high-speed.
 Increased vehicle
stability.

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Electric Power SteeringElectric Power Steering
 Reduced engine
drain.
 Improved fuel
economy and
acceleration.
 Instant-on power
steering.
 Added dependability
and assist even with
engine off.

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Active SuspensionActive Suspension
 Active suspension systems
move each wheel up and down
to control body motion in
response to road
abnormalities.
 With an active suspension, a
vehicle can simultaneously
provide the smooth ride of a
soft suspension along with
superior handling associated
with a firm suspension.

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Active Body ControlActive Body Control

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Dynamic Body ControlDynamic Body Control

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Active Body ControlActive Body Control

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Suspension Control in Action!Suspension Control in Action!

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Suspension Control in Action!Suspension Control in Action!

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All Wheel DriveAll Wheel Drive
 When accelerating, weight shifts to the rear,
reducing traction in front and AWD direct power to
the rear wheels.
 When braking, weight shifts forward, reducing
traction in back. With AWD, power is instantly
directed to the front wheels for better steering
control and braking performance.

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All Wheel DriveAll Wheel Drive
 Whether icy, oily, wet, or rough, if front
wheels start to slip, AWD system instantly
directs power the rear wheels; If rear
wheels start to slip, power is directed to
the front wheels.
 The power is automatically transferred to
the wheels with the best traction.
Unwanted understeer and oversteer is
virtually eliminated.

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Drive by WireDrive by Wire
 Replacement of traditional mechanical
systems for steering, braking, throttle and
suspension functions, with electronic
controller, actuators and sensors.

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Brake by WireBrake by Wire
 The braking process is triggered
in the conventional manner by
the brake pedal; In the process,
the pedal pressure and pedal
travel are measured by sensors
and converted into electronic
signals for the electronic control
unit (ECU). The unit that is
activated in this way controls the
four actuators at the wheel
brakes. The brake pads are
therefore forced together and
opened electromechanically and
no longer hydraulically.

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Sensotronic Brake ControlSensotronic Brake Control
 Mechanical components are replaced by electronics.
 Sensors pass the master cylinder pressure and the
speed with which the brake pedal is operated, to the
SBC computer.
 To provide the driver with the familiar brake feel, a
special simulator is linked to the tandem master
cylinder.
 Only in the event of a major
fault or power failure does
SBC instantly establishes a
direct hydraulic link between
the brake pedal and the front
wheel brakes.

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Sensotronic Brake ControlSensotronic Brake Control

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Sensotronic Brake ControlSensotronic Brake Control

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Steer by WireSteer by Wire
 Steer-by-wire system
eliminates the mechanical
connection between the
driver and the vehicle’s front
tires. The traditional steering
elements are replaced by
two actuators positioned in
the vehicle’s front corners.
These actuators receive
input from the control module
and turn the front wheels
accordingly. The system also
uses an electric motor to
provide road feedback to the
driver’s hand wheel.

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Electronic Throttle ControlElectronic Throttle Control
 Electronic throttle
control (ETC)
replaces the
throttle cables
that run from the
accelerator pedal
to the engine.

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Active Noise ControlActive Noise Control
 Traditionally noise is
controlled by passive
methods: enclosures,
barriers and silencers.
 Active control is used
when passive noise
control methods don’t
work.
 Secondary sources are
used to cancel noise from
primary source(s) by
introducing “antinoise”.

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Active Vibration ControlActive Vibration Control
 The primary way to cut off paths of noise and vibration
from engine is to use soft mounts. However, engine
mounts must also constrain or control engine excursions
caused by rough roads, firing in cylinders, wheel torque
reactions, etc. To limit engine motions, the engine mounts
should be stiff and heavily damped. These conflicting
requests on engine mounts have prompted automotive
industries to search for a new engine mounting method.

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Cruise ControlCruise Control
 The cruise control system controls the
speed of your car the same way you do by
adjusting the throttle position.

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Adaptive Cruise ControlAdaptive Cruise Control
 Adaptive cruise control (ACC) improves
on traditional cruise control by allowing a
vehicle to automatically adapt to the speed
of highway traffic.

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Stop and GoStop and Go
 The Stop & Go function maintains
longitudinal car control at low speeds,
e.g. when queuing on a motorway or
waiting at a traffic light.

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Anti Collision AssistAnti Collision Assist
 This system helps prevent collisions by sending
the driver an acoustic or visual signal to warn of
the presence of standing or slow-moving
obstacles in the car's path. The system also
acts on the car's brakes when necessary.

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Overtaking WarningOvertaking Warning
 The blind spot coverage sensor warns of the
presence of vehicles about to enter the side
area not covered by the door mirrors. The
sensor turns on a warning light, which can
be used in conjunction with the door mirror.
The warning signal becomes acoustic when
the turn signal is activated.

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Lane WarningLane Warning
 This additional driving support function
automatically detects car position in relation to
lane boundaries. The system issues an advance
warning if the car inadvertently crosses the lane
boundaries. The road in front of the car is filmed
by a micro TV camera and the driver may select
between tactile or acoustic indicators.

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Engine Control SystemsEngine Control Systems

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Engine Control SystemsEngine Control Systems

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Air/fuel Ratio ControlAir/fuel Ratio Control
 A fuel injector is an
electronically controlled
valve. It is supplied with
pressurized fuel by the fuel-
pump in your car.
 Two different injection
systems:
• Manifold injection.
• In-cylinder injection.
 Lambda: 14.7:1

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Effects of Air/fuel RatioEffects of Air/fuel Ratio

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Effects of Air/fuel RatioEffects of Air/fuel Ratio

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Knock ControlKnock Control
 Self inflammation of the air
fuel mixture.
• Increased ambient temperature.
• Increased load pressure.
• Bad fuel quality.
 Usual actuation is a
retardation of the ignition
angle.
 An alternative input: reduce
boost pressure of turbo
charger.

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Idle Speed ControlIdle Speed Control
 If the idle speed is unstable,
unpleasant vibrations or engine
breakdown when started may occur,
or fuel economy may drop.
 As a rule of thumb, fuel consumption
increases proportional to engine
speed at idling.
 The actuation variable at SI engines
is the mass air flow into the engine,
at diesel engines the injected fuel
amount.

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Saab’s Variable CompressionSaab’s Variable Compression
EngineEngine
 Improves fuel efficiency by up to 30
percent, reduces tailpipe emissions,
and doesn't negatively impact
overall performance.
 The SVC engine's cylinders are
located in the upper section.
 By adjusting the "slope" of the upper
part of the engine in relation to the
lower part by the use of hydraulic
actuators, the Saab engine can vary
the volume of the combustion
chambers. This, in turn, changes the
compression ratio.

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Variable Valve TimingVariable Valve Timing
 Valve timing changes with operating
conditions such as engine speed and
throttle position.
 The engine can rev higher, thus raises
peak power. For example, Nissan's 2-
liter neo VVL engine output 25% more
peak power than its non-VVT version.
 Low-speed torque increases, thus
improves drivability. For example, fiat
Barchetta's 1.8 VVT engine provides
90% peak torque between 2,000 and
6,000 rpm.

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Variable Valve TimingVariable Valve Timing

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Adaptive Transmission ControlAdaptive Transmission Control
 ATC adapts transmission shift
parameters according to
individual styles of driving (e.g.
aggressive vs. relaxed)
 Improves shift consistency and
transmission durability and
allows for shifting that is better
suited to specific driver styles or
operating conditions

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Continuous Variable TransmissionContinuous Variable Transmission
 An infinite number of gear ratios to
optimize performance and fuel efficiency.
 There are no more gear shifts as such,
which makes the CVT a highly
sophisticated gearbox for high levels of
driving comfort.
 The metal-link push belt permits high
torques of up to 400 nm to be transferred.
 The CVT's high gear ratio spread permits
the engine to be operated in the low-
consumption speed range.

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