Optical Fiber Technology in Automotive Industry

5/21/2018 Optical Fiber Technology in Automotive Industry

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FIBER OPTIC

TECHNOLOGY IN

AUTOMOTIVE INDUSTRY

BySAAHIL SINGHPES MODERN COLLEGE OF ENGINEERING


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FIBER OPTIC TECHNOLOGY IN

AUTOMOTIVE INDUSTRY

Fiber optic technology is becoming the medium of choice for a

variety of automotive applications. With its unique characteristics,

fiber optics are a naturally ideal choice for lighting, communications,

and sensing requirements.

Automobile manufacturers are using fiber for lighting applications for

several reasons:

First and foremost, fiber transmits cold light, making it a safe

alternative to traditional sealed beam or halogen lighting.

The light source is easily accessible and offers much more increative freedom of design.

Fiber also allows for light source and output location separation,


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AUTOMOTIVE INDUSTRY

Fiber creates high performance lighting options with reducedphysical space requirements for difficult and restricted access

locations.

Communications and sensing in automobiles is of utmost

importance with the continual increase in onboard safety devices

and systems. With each subsequent model year, more and more airbags, traction

control devices, and safety systems are integrated into automobiles

for passenger safety.

With most of these systems focused on emergency or pre-

emergency response, rapid communication to and from themonitoring system to the sensor or active module is critical to

successful operation.

With the large bandwidth, EMI and RFI immunity, and relatively low

cost, more and more manufacturers are utilizing fiber as the

communication method of choice for these mission criticalapplications.


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AUTOMOTIVE INDUSTRY

There are three basic fields of application of

optical fiber technology in automotive field:

FIBER OPTIC LIGHT SOURCES

IN-VEHICLE NETWORKS

OPTICAL SENSORS


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Fiber Optic Light Sources


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What is an Optic Source?

The heart of a fiber optical data system

A Hybrid Device

Converts electrical signals into optical signals

Launches these optical signals into an optical

fiber for data transmission.

Device consists of an interface circuit, drive

circuit, and components for optical source.(LEDs, ELEDs, SLEDs, LDs, etc)


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Why Use Fiber Optics For Lighting?

Heat-Free Lighting: Since the light source is remote, the fiber

transmits the light but isolates the heat from the light source from the

illumination point, an important consideration for lighting delicate

objects, that could be damaged by heat or intense light.

Electrical Safety: Illumination in hazardous atmospheres can be

done safely with fiber optic lighting, since the fiber is nonconductive

and the power for the light source can be placed in a safe location.

Even many lights are low voltage.

Precise Spotlighting: Optical fiber can be combined with lenses to

provide carefully focused light on extremely small spots,or simply

light a specified area precisely.


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Durability: Using optical fiber for lighting makes for much more

durable lighting. Optical fiber, either plastic or glass, is both strong

and flexible, much more durable than fragile light bulbs.

The Look of Neon: Fiber that emits light along its length, generallycalled edge-emitting fiber, has the look of neon tubes for decorative

lighting and signs. Fiber is easier to fabricate, and, since it is made of

plastic, is less fragile.

Vary the Color: By using colored filters with white light sources, fiber

optic lighting can have many different colors and by automating the

filters, vary colors in any preprogrammed sequence.

Simpler Installation: Fiber optic lighting does not require installing

electrical cables, instead a fiber is installed to the location and fixed in

place, perhaps with a small focusing lens fixture, a much simpler

process. Often several fibers can use a single light source, simplifying

installation even more.

Easy Maintenance: With fiber, the source can be in an easily

accessible location and the fiber in any remote place. Changing the

source is no longer a problem.


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DIRECTING LIGHT INTO FIBER


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How Fiber Optic Lighting Works

Fiber optic lighting uses optical fiber as a light pipe, transmitting

light from a source through the fiber to a remote location. The light

may be emitted from the end of the fiber creating a small spotlight

effect (also called end glow) or emitted from the outside of the fiber

along its length, looking like a neon or fluorescent tube (also called

side glow).

The light source is usually called a fiber optic illuminator and

consists of a bright light source and often some optics to efficiently

focus light into the fiber. Sources must be bright, so quartz halogen

or xenon metal halide lights are commonly used. Smaller fibers may

also use LEDs which very efficiently couple light into fibers but do

not achieve the light levels of the other lamps.


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How Fiber Optic Lighting Works

Optical fibers used for lighting are similar to fibers used in

communications, but optimized for transmitting light not high speed

signals. Unlike communications fibers that use small cores to

maximize bandwidth, lighting fibers use large cores with thin

claddings to maximize coupling of the light from the illuminator into

the fiber.

Lighting fibers can be made of glass, just like communications

fibers, or plastic. Larger diameter plastic fibers are also used,

perhaps more commonly, because they are inexpensive and easier

to install, but they have higher light loss and cannot withstand as hot

a temperature, sometimes limiting the light input from a source.


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End Emitting Fiber

End-emitting fiber is generally a step-index multimodefiber with a large transparent core that transmits the lightand thin transparent cladding that traps the light in thecore due to total internal reflection. The core is large incomparison to the thin cladding as that makes it more

efficient in coupling light from the illuminator. The claddingdoes not transmit light, so any light coupled into thecladding will not be transmitted by the fiber.

End-emitting fibers are generally made from plastic as it

can be made in larger sizes than glass and is lessexpensive and easier to install.


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Edge Emitting Fiber

Edge-emitting fiber is basically similar to end-emittingfiber except the core/cladding boundary is designed tobe slightly inefficient.

Instead of trapping all the light in the core, the boundary

is rough and some light is scattered into the claddingwhere it becomes visible.

Since much of the light is lost by the edge-emissionalong the fiber, edge-emitting fiber has high attenuation.

This may limit the lengths of edge-emitting fiber that canbe used.

This can be alleviated by illuminating the fiber from bothends by using two illuminators


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In-Vehicle Networks


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In-Vehicle Networks

Most innovations in the car industry today are made in

the electronics area. This is especially true in relation to

the systems for communicating information around the

car, As a result, both the number of nodes in a car's

network, as well as the complexity of these nodes, isincreasing, and so the total bit rate carried over digital

communication channels is growing exponentially.

Traditionally, the physical medium used to carry data in acar has been shielded copper lines for both the power

supply and communication. Copper cables are heavy,

and their weight impairs fuel efficiency.


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In-Vehicle Networks

Fibre optic cabling would appear to be the answer to the

car designer's wish: it is light and compact, and it also

offers the benefits of supporting very high data rates and

of immunity from Electro-Magnetic Interference (EMI).

In regard to the cable, Polymer Optical Fibre (POF) is

preferred in automotive applications. Although it suffers

from much higher losses than glass fibre, it is cheaper

and can withstand a tighter bend radius than glass. Inhigh-bandwidth applications, where POF cannot provide

an adequate data rate, plastic-clad silica fibres and multi-

mode glass fibre bundles are now used.


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Why POF?

The number of electronic devices in a car

increases year by year, primarily due to an

increase in the entertainment equipment desired

for modern passenger carsfrom simple radiosin the 1970s to radios, DVD players, TVs, and

even GPS consoles. To realize ubiquitous

access to multiple digital equipment sites in a

car, each equipment site or node must beconnected, leading to an exponential increase in

the number of communication cables within the

vehicle.


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Why POF?


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WHY POF?

Automotive manufactures are keen to exploit POF

technology for connecting car infotainments systems and

even some safety-critical applications such as airbags.

Todays high-end cars are processor intensive,

supporting devices such as radio, CD, DVD, navigation

systems, Bluetooth, telephones, TV tuners, gaming and

even internet, etc.

POF will connect up the ever-increasing number of in-car

electrical devices such as TV, computer, fax machinealso into a car.


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WHY POF?

BENEFITS OF POF:

High Operation Bandwidth.

Increased Transmission Security.

Increased Reliability.

Immunity to EMI and anti-shock.

Ease of Handling, Connection and Installation. Flexibility of Design.

Long Shelf Life.

Crucially, its also a Low-cost Option.


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STRUCTURE OF POF

Common POFs in use today typically have a 980-m-

diameter polymethylmethacrylate (PMMA) core and a

1000-m-diameter fluorinated polymer cladding. The

fiber is jacketed with polyamide (PA) material to enhance

its robustness in vehicle use.

The high numerical aperture (typically 0.50 to 0.58), easy

connection ability, and mechanical strength and flexibility

of POF have cemented its use in automotiveinfotainment (information and entertainment) networking

systems in passenger cars since the late 1990s.


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STRUCTURE OF POF


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END TERMINATION OF POF

The POF cable and

connectors in the MOST

standard have a simple

structure, making them as

easy to produce and connect

as copper cables. In anautomated production line, end

termination is completed in two

seconds using a laser welding

method. An inline POF coupler

is used for fiber-to-fiberconnection between

equipment nodes.


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Roadmap of in-vehicle networks


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Overview of In-Vehicle

Networks

D2B (Domestic Data Bus ): DaimlerChrysler (formerly Daimler-Benz) first introduced

POF into its S-series Mercedes-Benz back in 1998,

using a simple optical data bus system called D2B. D2B was designed for audio-video communications,

computer peripherals, and automotive media

applications.

The D2B enables complex and distributed functions,minimizes electromagnetic-interference problems,

decreases weight and cost, and achieves a high data

rate of up to several megabits per second.


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Networks

Media-Oriented Systems Transport

(MOST): MOST, a bus protocol, promoted and organized by the

MOST Cooperation (Karlsruhe, Germany) and led by

Daimler Chrysler, BMW and Audi, was devised in the

late 1990s to meet the rapidly increasing in-car data

bandwidth for vehicle entertainment systems.

MOST25 initially offered 25Mbps and more recently.MOST50 offers up to 50Mbps data bandwidth using POF

as the physical media.


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Networks

The interconnection of telematics and infotainment such

as video displays, GPS navigation systems, active

speaker and digital radio. Over 22 models of car are equipped with MOST

systems, with the Mercedes E-Class, BMW 7 Series,

Porsche Cayenne, Saab 9.3, Audi A8, and Volvo XC-90

among the first to deploy the technology commercially.

With MOST, the automobile industry developed a unified

standard that everybody abides to, with the intention of

driving cost down.


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Networks

Byteflight:

Developed from 1996 by BMW. A flexible time-division multiple access (TDMA)

protocol using a star topology for safety-related

applications.

ByteFlight is used to support the rapidly growingnumber of sensors, actuators and electronic

control units within cars.


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Networks

The physical medium used is plastic optical

fiber.

BMW is the only car maker currently deployingthe Byteflight technology.

Safety-critical systems need deterministic

protocols with fault-tolerant behaviour. ByteFlight

guarantees high data integrity at a data rate of

10 Mbit/s and an information update rate of 250

s.


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Future Needs for Networking


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OPTICAL SENSORS


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AUTOMOTIVE APLLICATIONS

FOR OPTICAL SENSORS

Automotive sensors must operate in harsh

environmental conditions viz:

High Temperature

Vibration

Corrosive fluids, etc.

Achieving the required performance at the right (low!)cost is always paramount.


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AUTOMOTIVE APLLICATIONS

FOR OPTICAL SENSORS

Fibre-optic sensors (still) cost too much for mass-market

automotive use: data links for infotainment are the only

current automotive market for fibre-optics.

But there are some optical sensors in volume production,

and fibre-optic sensors are very useful for

instrumentation.


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Optical Torque and Angle Sensor for Electric

Power Steering

A power steering system is a torque servo system. The system

determines how much torque is being applied to the steering wheel

by the driver, and adds an appropriate amount of torque assistance

to keep the applied torque to the required value.


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Optical Torque and Angle Sensor for Electric

Power Steering

An optical torque and rotation angle sensor, which

detects the drivers applied torque and transmits torque

data to the system Electronic Control Unit (ECU).


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Automatic Headlight / Windscreen

Wiper System

Rain / light sensors are attached to the front windscreen

and automatically the windscreen wipers and headlights

turn on and off depending on pre-determined external

conditions.

The rain sensor technology is based on an IR systemthat measures differences due to refraction in the optical

path.

The light sensor consists of independent forward and

horizontal looking receivers to determine tunnels,bridges and specific ambient conditions (eg dawn) for

automated headlight control.


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Automatic Headlight / Windscreen

Wiper System

To detect the presence of

rain on the windscreen, an

IR beam is reflected from

the outer windscreen

surface back to a IRsensor array.

When a rain drop strikes

the windscreen, some IR

energy is transmitted out

through the droplet: thesystem detects the change

in reflected IR energy.


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Lane Guidance Systems

Video camera technology

enables a range of safety

systems which are supported

by a forward-looking

monocular camera mounted at

the windscreen in the rear-view mirror mount.

Lane Departure Warning

(LDW): detects lane markings

in front of the vehicle and

provides a warning if the driverunintentionally leaves the

driving lane.

Lane Departure Warning


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Lane Guidance Systems

Lane Keeping Assistance

(LKAS): combines lane

detection with an electric

steering system to provide a

torque overlay on steering,

automatically directing thevehicle back into the correct

lane.

Other possible functions: Auto

Lane Guidance.

Obstacle / pedestriandetection, traffic sign

recognition, forward collision

warning.


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CONCLUSION

Photonic technologies are superior to electronicsolutions in terms of data rates, bandwidth, reliability,

and robustness.

But they still need to prove they are capable of replacing

their electronic counterparts.

It may take time for fiber to spread beyond high-end

luxury cars.

Fiber costs remain higher than those for copper cable,

but fiber costs will come down as production increases.

Mass production of plastic fibers could help the

technology spread.


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FOR YOUR TIME AND PATIENCE

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Optical Fiber Technology in Automotive Industry