AUTOMOBILE INSTRUMENTATION

Technical Paper Presentation

Instrufiesta – 2006

By :

- Himanshu Madan

- Siddharth Shashidharan

C.O.E.P - T.Y (E&TC)

ABSTRACT

From the days of Henry Ford’s automated assembly production line, we

have come a long way into an era of intelligent automated cars that provide the

ultimate in security, comfort and functionality to the demanding empowered

customer.

A few years ago, instrumentation for the populace meant a few indicators

that told them the essential statistics of their vehicles, like the temperature, fuel

level, speed, mileage etc.

Things are far different today. People want vehicles that are capable of

driving themselves, that can park themselves and even warn of impending

collisions thereby reducing significantly the number of fatal crashes.

The car ought to be ‘intelligent’ enough to speed up on highways and slow

down in traffic (Adaptive cruise control). It also needs to provide the best drive

possible in terms of comfort, i.e automatically configuring its suspension systems

(Active body control), traction control on the wheels and advance lighting

systems (AHS) that account for curves and oncoming traffic as well as low

illumination.

This is being made possible thanks to recent developments in science and

technology and the seemingly effortless confluence of semiconductor electronics,

precision transducers and modern mechanical instrumentation systems. The

brain of the automobile, the microcontroller chip, is fed a continuous stream of

data via sensors that monitor virtually every aspect of the car’s functioning.

Pressure on accelerator and brake pedals, oxygen content in the fuel-air

mixture, engine temperature and friction etc. are sensed and the engine load is

varied. Electronic stability control (ESC), power steering assistance (EPS),

collapsible steering, auto-deployment airbags, keyless entry using biometrics and

RFIDs provide safety and security.

GPS, Bluetooth and WiFi connectivity is also being used for

communication between two vehicles for essential data-communication. Other

advances also include temperature and climate control, self-cleaning headlights

and windshields, tyre pressure monitors, external noise cancellation, auto-folding

anti-glare mirrors.

The good old car has indeed come a long way and thorough instrumentation of virtually every facet of the automobile has, in no insignificant way, helped to lay the foundations for the future; a future that promises efficiency, safety, functionality, ergodynamics, comfort, reliability, security and luxury.

Contents:

Performance enhancement: Instrumentation in cars used to enhance the performance and overall handling of the car.

Intelligent Light System Active Body Control Traction Control Electronic Stability Control

Engine instrumentation: Monitor and control the parameters and functions of the engine.

Engine Control Unit

Safety: Instrumentation to reduce fatalities and provide the ultimate in safety for the passengers.

Airbags, Seats and Seatbelts Anti-Lock Braking System Tyre Pressure Monitoring

Automation: Assistance and automated features that overcome common hassles.

Active Cruise Control Parking Assistance System Automatic Parking System Automated Highways

Smart features: Modern systems that are designed to make the vehicles more intelligent and further assist the passenger.

Rainfall Sensors Noise Cancellation Systems Global Positioning Satellite System

Other modern automobile instrumentation systems: Bluetooth and WiFi Automatic Headlight Wash Climate Control Keyless entry and RFIDs

Intelligent Light systems

The Intelligent Light System is

a new generation of adaptive

car headlamps which adjust to

suit prevailing driving and

weather conditions.

The optional active headlight

system uses intelligent

technology to enable a pair of

Bi-Xenon headlights to follow

the shape of the road through an arc of 15 degrees, providing drivers with up to

90 percent more visibility. The system is controlled by data provided by steering

angle and yaw rate input sensors as well as vehicle speed and GPS-fed road

data. Combined with bi-xenon headlamps, new lighting functions include country

road and motorway

light modes which

increase the driver’s

range of visibility by up

to 50 metres. The light

system also includes extended fog lamps which

illuminate the road edges and therefore provide even better orientation when

visibility is poor. The country road mode upgrades the low-beam lighting,

illuminating the driver's side edge of the road more widely and brightly, enlarging

the field of view by at least 10 metres. The motorway mode engages in two

stages once the vehicle reaches a speed of 90 km/h. In the first of these stages,

bi-xenon lighting output is increased from 35 to 38 watts. In stage two the range

of the driver's-side headlamp is increased when a speed of 110 km/h is reached,

extending the range of the low-beam lights by around 50 metres. With the

extended fog lamps, the left headlamp swivels outwards eight degrees and, at

the same time, lowers the cone of light. This illuminates the nearside of the road

more efficiently, while the wider beam reduces backglare in fog.

Active light at cornering Active light at high speed

Active body control

The hydraulic ABC chassis offers you supreme ride comfort at all times by

combining active control with passive damping to reconcile the two conflicting

objectives of dynamism and comfort. You are able to choose between a more

comfort-orientated and a sporty ride at the push of a switch. The system even

takes the load your vehicle is carrying into account to restrict vehicle body motion

as required when pulling away, cornering or braking, and to dampen such motion

as effectively as possible. ABC is the first suspension system in the world to be

actively controlled by computer. The super-fast computational unit teams up with

high-pressure hydraulics and a sophisticated system of sensors to automatically

adjust the position of the vehicle body. The ABC control unit is capable of

reacting to all manners of driving situations in an instant by directing a precisely

metered quantity of hydraulic fluid to each individual damper strut as the situation

dictates. This enables ABC Active

Body Control to all but eliminate the

pitching motion that would otherwise

occur at times when pulling away

from standstill or braking, as well as

the body's tendency to roll in

corners, translating into a palpable

improvement in ride comfort. ABC

incorporates load-sensitive self-levelling suspension front and rear, providing you

with the additional convenience of being able to raise the vehicle's ride height

when driving over rough roads or through snow. One can engage one of two

drive modes (+24 millimetres and +49 millimetres). If neither of these modes is

selected, the vehicle's ride height starts to drop automatically above a speed of

60 km/h to reduce drag, until reaching a point 15 mm below the standard ride

height at a speed of 140 km/h. If the speeds fall back below 140 km/h, the

vehicle will start to rise again accordingly. The upshot is a marked enhancement

of ride comfort, handling dynamics, motoring pleasure and safety in any situation

out on the road.

Variable hydraulic suspension

Traction control

Traction control deals specifically with lateral (front-to-back) loss of friction during

acceleration. In other words, when your car accelerates from a dead stop, or

speeds up while passing another vehicle, traction control works to ensure

maximum contact between the road surface and your tires, even under less-than-

ideal road conditions. For example, a wet or icy road surface will significantly

reduce the friction (traction) between your tires and the pavement. And since

your tires are the only part of your car that actually touches the ground, any

resulting loss of friction can have serious consequences. Traction control works

at the opposite end of the scale from ABS — dealing with acceleration rather

than deceleration. Still, since many of the same principles apply to both systems,

it might be best to visualize it as sort of ABS in reverse. ABS works by sensing

slippage at the wheels during braking, and continually adjusting braking pressure

to ensure maximum contact between the tires and the road.

Enter electronic traction control. In modern vehicles, traction-control systems

utilize the same wheel-speed sensors employed by the antilock braking system.

These sensors

measure differences

in rotational speed to

determine if the

wheels that are

receiving power have

lost traction. When

the traction-control system determines that one wheel is

spinning more quickly than the others, it automatically

"pumps" the brake to that wheel to reduce its speed and

lessen wheel slip. In most cases, individual wheel braking is

enough to control wheel slip. However, some traction-control

systems also reduce engine power to the slipping wheels.

Central microprocessor counters individual wheel slipping.

Pulsed braking.

Electronic stability control

ESC compares the driver's intended direction in steering and braking inputs, to

the vehicle's response, via lateral acceleration, rotation (yaw) and individual

wheel speeds. ESC then brakes individual front or rear wheels and/or reduces

excess engine power as needed to help correct understeer (plowing) or oversteer

(fishtailing). ESC combines anti-lock brakes, traction control and yaw control

(yaw is spin around a vertical axis). The system is fully independent of the

driver's actions. Even if the car is free-rolling (no acceleration or braking input

from the driver), the stability control system will kick in and perform its duty. Its

key component is a

yaw velocity sensor.

This sensor

permanently tracks

the movement of

the vehicle around

its vertical axis,

comparing the

actual measured

reading with the

target value derived

from the driver's steering commands and the vehicle's speed. This information is

then fed into a microcomputer that correlates the data with wheel speed, steering

angle and accelerator position, and, if the system senses too much yaw, the

appropriate action to preempt the risk of skidding is taken. Fishtailing is actively

suppressed by applying the brakes at the front left and right wheels individually

and alternately. In the majority of cases, this is sufficient to eliminate the weaving

motion completely, and with it the threat of danger. If the snaking motion is

particularly severe, however, the engine's torque will also be throttled and the

towing vehicle's brakes applied at

all four wheels to bring the speed

below the critical range quickly.

Without ESC With ESC

Components of ESC

Engine Control Unit

Also known as Engine Management System (EMS), it is an electronic system,

fundamentally a computer, that controls an internal combustion engine by

reading several sensors in the engine and using the information to control its

ignition systems.

Because the ECU is dealing with actual measured engine performance from

millisecond to millisecond, it can compensate for many variables that traditional

systems cannot, such as ambient temperature, humidity, altitude (air density),

fuel octane rating, as well as the demands made on it by the driver.

Modern ECUs use a microprocessor which can process the inputs from

the engine sensors in real time. An electronic control unit contains the hardware

and software (firmware). The software is stored in the microcontroller or other

chips, typically in EPROMs or flash memory so the CPU can be re-programmed

by uploading updated code. This is also referred to as an (electronic) Engine

Management System (EMS).

It also communicates with

transmission control units or directly

interfaces electronically-controlled

automatic transmissions, traction control

systems, and the like. The Controller

Area Network or CAN bus automotive

network is often used to achieve communication between these devices.

Parameters that are mapped are:

Ignition: Defines when the spark plug should fire for a cylinder

Rev limit: Defines the max RPM that the engine is allowed to rev to. After this fuel

and/or ignition is cut.

Water temperature correction: Allows for additional fuel to be added when the

engine is cold (choke).

Transient fueling: Tells the ECU to add a specific amount of fuel when throttle is

applied.

Engine control unit

Low fuel pressure modifier: Tells the ECU to increase the injector fire time to

compensate for a loss of fuel pressure.

Closed loop lambda: Lets the ECU monitor a permanently installed lambda probe

and modify the fueling to achieve stoichiometric (ideal) combustion.

Some of the more advanced ECUs include functionality such as launch control,

limiting the power of

the engine in first

gear to avoid

burnouts.

Other examples of

advanced functions

are:

Waste gate control:

Sets up the

behavior of a turbo

waste gate,

controlling boost.

Banked injection:

Sets up the behavior of double injectors per cylinder, used to get a finer fuel

injection control and atomization over a wide RPM range.

Variable cam timing: Tells the CPU how to control variable intake and exhaust

cams.

Gear control: Tells the ECU to cut ignition during (sequential gearbox) upshifts or

blip the throttle during downshifts.

In order to communicate with the driver, an ECU can often be connected to a

"data stack", which is a simple dash board presenting the driver with the current

RPM, speed and other basic engine data. These stacks, which are almost always

digital, talk to the ECU using one of several proprietary protocols running over

RS232, CANbus or ethernet.

ECUs allow greater fuel efficiency, better power and responsiveness, and much

lower pollution levels than earlier generations of engines.

ECU schematic

Airbags, seats and seatbelts

Manufacturers today lay great emphasis on safety and comfort of the

passengers. Airbag deployment is now controlled by a number of factors.

The impact of a collision is sensed and

fed to the computer.

Modern systems like Jaguar’s Adaptive

Restraint Technology System (ARTS)

use ultrasonic sensors to identify not

only size and weight of occupants, but

also when they are out of the typical

seating position. The vehicle's computer then

determines the appropriate size and force of

airbag deployment. Furthermore, when an

impact is sensed, belt tensioners remove slack

and belt force

limiters regulate the restraining force with

flexibility. Airbags and seat belt systems are

increasingly operating "intelligently" in unison

with one another.

In an effort to improve comfort, The Active

Comfort Seat uses a sophisticated system of motors and hydraulic chambers to

move the seat up and down by 15 mm in a programmed fashion every 60

seconds imparting a gentle rocking movement of the pelvis that is almost

imperceptible, thus increasing blood circulation and making long drives more

comfortable. Many of tomorrow’s models will feature additional comfort features

like ergonomic self-adjusting seat

position sytems and user controlled

seating with memory settings that

remember the user’s preferred

seating position.

ANTI-LOCK BRAKING SYSTEM - ABS

ABS systems were introduced to the commercial vehicle market in the early

1970's to improve vehicle braking irrespective of road and weather conditions.

The four-wheel ABS or Anti-lock Braking System is designed to help the driver

maintain steering control during hard braking, especially in slippery conditions. It

prevents the wheels from locking up, helping you maintain steering control during

braking. In a similar situation, driving a car equipped with four-wheel ABS, it

would be easier for you to steer your vehicle while braking.

The four-wheel ABS system can help to slightly reduce the braking distance in

some situations. However, under certain conditions (e.g. on loose snow or

gravel), the braking distance may be longer.

How the actual ABS system works

Major components of the typical ABS

system include four speed sensors

(one at each wheel), an electronic

control unit (ABS computer) and a

hydraulic control unit (see the picture).

The ABS computer constantly monitors

the signal from each wheel speed

sensor. When it senses that any of the

wheels are approaching lock up during braking, the ABS computer sends the

signal to the hydraulic control unit, which modulates the braking pressure for a

corresponding wheel(s) preventing it from locking up. In modern systems, two

more sensors are added to help the system work: a wheel angle sensor, and a

gyroscopic sensor. When the gyroscopic sensor detects that the direction taken

by the car doesn't agree with what the wheel sensor says, the ABS software will

brake the necessary wheel(s) so that the car goes the way intended.

ABS hydraulic control unit

Braking on the snow without ABS

Tyre Pressure Monitoring

Tyre pressure monitoring detects even small pressure fluctuations, locates the

affected tires and informs the driver with warnings of varying urgency. Function:

A co-rotating wheel module with an integrated valve measures tire pressure and

temperature and transmits these data as an HF radio signal. Two functional

variants have been developed to receive and process the data:

TPMS A: 4 wheel modules, 4 antennas with HF coupler

The receiving antennas are located on the

connecting cables for the wheel speed

sensors. They send the data to the EBS-ECU,

which then analyzes them in an intelligent

warning strategy unit. We are the only supplier

that can offer this technology without any

additional cable, receiver and ECU.

TPMS B: 4 wheel modules, 1 central

antenna

This more economical solution with a central

receiver in the EBS control unit is used when

the maximum transmitting power is allowed for

the wheel modules. Through a combination

with DDS and intelligent data processing, this

system is able to assign the 4 received

pressures to the 4 wheels (autolocation

function) even with only one receiving antenna.

In case of failure of sensors, DDS is used as a

fallback solution.

Future generations of systems networked with TPMS, DDS and ESP will make

important contributions to active accident avoidance, such as ESP control

dependent of tire pressure and load-dependent tire pressure recommendation. A

sensor-transponder integrated in the tire without a battery will supply pressure

and temperature data as well as information about the tire itself.

Active cruise control

Much of everyday driving takes place in a

stream of traffic, one car following another.

Given the high incidence of rear end

collisions, Adaptive Cruise Control Systems

(ACCS), which control the vehicle speed in

a manner than will maintain a safe following distance, show great promise.

Radar headway sensors and newer

systems like rotating LASERs

detect other vehicles and obstacles

on the road ahead by their

reflections. The microcomputer in

the car then calculates the actual

distance and decides the optimum

seperation length and speed at

which to follow the car in front. This

option enables the driver to relinquish control partially to the car computer which

continues to follow the car ahead whilst maintaining a safe distance. It thus slows

down and speeds up automatically with the car in

front requiring minimal effort on the driver’s

part.

Advancements in

these systems

also include

lane departure warning systems and lateral/side

sensing control systems. A mounted camera

visualises the lane markings on the road and uses DSP to analyse it. The

software is incredibly sophisticated and is able to distinguish different types and

colors of lane markings in different lighting and weather conditions. Radars are

used to monitor blind spots.

Parking assistance systems

Position of front looking RADAR

RADAR Tx / Rx

Overhead camera

Computer monitors lane marking

Parking assistance systems automatically warn the driver of obstacles to the

front and rear of the vehicle when manoeuvring. Based on the echo-sounder

principle, the system has a total of ten sensors – six in the front bumper and four

in the rear bumper. These send out ultrasonic signals which are reflected by

other vehicles or obstacles. A microprocessor calculates the actual distance and

informs the driver by means of visual

displays on the dashboard as well as

by audible warning tones. The

system monitors an area extending

between 15 and 80 cm at the front of

the vehicle and between 20 and 120

cm at the rear. If an obstacle is detected within this area, the visual and audible

warnings are activated – the visual warning is triggered first and is

complemented by the audible warning when the obstacle is about 35 cm away.

Whereas only the front sensors are active when moving forwards, both the rear

and front sensors are active when reversing.

Automatic parking system

Linear or automated garage parking has been

a feature of high end cars for a while now.

Recently though, parallel automatic parking

systems, have been developed, which when

activated, uses ultrasonic sensors to scan for

empty parking spaces. When a spot suitable to

the length of the car is found, the car’s

computer takes over. The steering and acceleration is controlled by the car

computer and the driver simply watches as the car squeezes itself into tight

spots. This facility is already available in some BMW, Mercedes and Honda

variants. Commercially this facility is an eye-catching USP for modern vehicles

and therefore viable.

Automated highways

A vehicle that can “predict” the actions of neighboring vehicles is an important

step for safer highway transportation. This can be accomplished through multi-

sensor systems for adjacent vehicles and possibly inter-vehicle communications

to give an idea of what to expect beyond adjacent vehicles. Alternatively, the

roadside control may have knowledge of the positions of the vehicles relative to

fixed reference points. Roadside monitors will measure traffic flow and speed,

and vehicle paths will be calculated based on this information. Such

measurements are currently made with loop detectors, ultrasonic sensors, AVI

tags or vision systems. Information may be

communicated by infrared beacons, broadcast

and cellular radio, or using emerging ultra

wideband technologies. The vehicles need

longitudinal sensors to measure distance and

relative speed of the preceding vehicle, which

are based on radar, ultrasound, or vision. Microwave radar sensors perform very

well in fog and heavy rain, but they are very expensive. Laser radar systems are

low-cost, but cannot handle low visibility conditions. To facilitate lane changes at

a range of relative speeds, the vehicle must be

equipped with sensors that locate vehicles on the side

with a longitudinal range of about 30m. Infrared and

laser range finding techniques may prove to be useful

in this area. Besides headway and side sensor

information, longitudinal and lateral velocity and acceleration, yaw rate, front

steering angle, and lateral deviation data is needed to obtain a robust combined

lateral and longitudinal control. All of these except the last one can be obtained

using on-board accelerometers and encoders. For vehicle position sensing, there

are two alternatives: magnetic markers, and vision systems. An eight-vehicle

platoon demonstration at the National Automated Highway Systems Consortium

Technical Feasibility Demonstration, held in San Diego from August 7-10, 1997,

successfully demonstrated the technical feasibility of operating standard cars.

Rainfall sensors

Magnetic loops for lane ID

Ceramic magnets

The rain sensor controls the windscreen

wipers autonomously. The electronics control

the wipers to give you an optimum view

through the windscreen whilst ensuring that

the windscreen wipers do not run over a dry

windscreen. The sensors make allowances

for the sensitivity of the human eye at night-

time and the frequency of the intermittent

wipe varies according to the vehicle's speed. Invisible beams of infrared light

transmitted by two light-emitting diodes scan an area of the windscreen on a

level with the rear-view mirror. The light beams are

reflected with varying intensity depending on how heavy

the rainfall is or how wet the windscreen is. A sensor

responds to the reading by adjusting the wiper interval

appropriately. If a few drops suddenly turn into a downpour, the system switches

from intermittent to continuous wipe, smoothly increasing the wiper speed in the

process as required. The reverse applies when the rain eases off again.

Noise cancellation system

Microphones located in the front and rear of the car’s interior on the ceiling listen

to the low-frequency wind and engine (road) noise inside

the car. It processes this and inverts the signal, feeding a

sample of it to the car’s stereo which then

plays an anti-noise signal that is 180 out of

phase with the original noise. This results in

destructive interference which effectively

blanks out the said noise. The noise

cancellation system also ensures that it doesn’t

cancel out the music on stereo output by

effectively matching the digital audio content.

Global Positioning Satellite Systems

Rain sensor

Rainfall monitored wiper system

A GPS unit consists of a space segment, a control segment, and a user

segment. The space segment is a constellation of two dozen satellites orbiting

the earth twice every 24 hours, at approximately 10,900 nautical miles above the

earth's surface, funded and controlled by the U.S. Department of Defense. The

control segment is a series of monitoring stations located at different sites on

earth that update and correct errors in the navigational message of the satellites.

The user segment is a receiver that receives radio waves from the satellites in

orbit and can determine how far away it is from each satellite by keeping track of

the time it takes for a radio wave to travel from the satellite to the receiver.

Four satellites are used

simultaneously to pinpoint the

precise position of the receiver on

the earth. Information from the first

three satellites narrows down the

range of possible locations to two

points; one of these is usually

illogical and indicates a point not on the earth. A fourth satellite is used to confirm

the target location. When installed in a car, a GPS unit can provide useful

information about the car's position and the best travel routes to a given

destination by linking itself to a built-in digital map. A monitor in the car shows the

relevant portion of the map. The driver can enter the target location, and the

computer will calculate the optimal route and display it instantly. It can respond to

user preferences and map a route that avoids highways or avoids local roads. If

the map is detailed enough, it will also provide the locations of the nearest gas

station, supermarket, restaurant, hotel, and ATM machine.

GPS also tracks the distance traveled on a particular trip, vehicle mileage,

and speed. It can keep a record of driving activity, including the address of each

destination, names of streets traveled, and how long the vehicle remained at

each location. GPS can also issue warnings when the car is speeding, aid in

recovery of a stolen car.

Other Modern Automobile Instrumentation Systems

Bluetooth and WiFi connectivity

Modern cars will feature

Bluetooth and WiFi connectivity

for entertainment, internet access

as well as exchange of important

information from one car to the

next viz. speed, traffic conditions,

accident warning and other

practical data.

Self-cleaning Headlights

Sensors in the car sense the

reflection off the protection

glass when the headlights

are turned on. It is thus able

to judge if the glass is dirty,

and automatically shoots a

jet of water to clean it.

Climate Control

Sensors monitor the temperature,

humidity, air quality etc. and

accordingly activate the climate

control system to provide ideal

climate conditions. It also makes

efficient use of re-circulated air and

enhances passenger comfort.

Keyless Entry and RFIDs

It eliminates the need for keys in the car. The car comes equipped with a

unique radio frequency tag which only the corresponding wireless key can

open. Starting the car in these cars is a simple push-button.