perform a dedicated narrow range of functions as part of large - PowerPoint PPT Presentation

 Necessity is the mother of invention and embedded systems are inventions that were fuelled by the idea of making pre-programs to perform a dedicated narrow range of functions as part of large systems.  An embedded system is a device controlled by instructions stored on a chip. These devices are usually controlled by a microprocessor that executes the instructions stored on a ROM chip  Almost every car that rolls off the production line these days makes use of embedded technology in one form or the other

 They are in a sense ubiquitous, that is, almost invisible to the user and almost omnipresent  Processors and their peripherals have squeezed into the side- and rear-view mirrors, wheel rims, headliner, gas tank, seat cushions, headrests, bumpers, and every other crevice of a modern car.  Dashboard electronics such as the radio, air conditioning, and satellite navigation system are just the obvious ones.

 Cars make a great vehicle for deploying embedded processors in huge numbers “Thanks to the magic of microprocessors and embedded systems, our cars are becoming safer, more efficient, and entertaining.”

 The first car to use a microprocessor was the 1978 Cadillac Seville.  The chip, a modified 6802, drove the car's "Trip Computer," a flashy dashboard bauble that displayed mileage and other trivia.  Today that kind of microprocessor muscle could barely adjust your mirrors .  Now cars have 100s of microprocessor.

 The current 7-Series BMW and S-class Mercedes boast about 100 processors apiece.  A relatively low-profile Volvo still has 50 to 60 baby processors on board.  Even a boring low-cost econobox has a few dozen different microprocessors in it.

 Antilock brakes have been microprocessor-controlled for years; now the brakes themselves can be computer controlled.  Mercedes-Benz offers Brake Assist, a system that decides when the driver isn't pressing hard enough on the pedal and creates its own panic stop.  The system is said to shorten emergency stops by a significant amount, but also makes the car difficult to drive smoothly in slow traffic.  Processors tell us when our tires need air. Henceforth, cars have sensors mounted to the metal wheel rims and a "light" on the dashboard saying it's time to top up the O2.

 New lane-departure warnings may supplement the venerable Botts dots.  An image-sensor system from Iteris looks for painted stripes and other lane markings. If it feels the driver is about to wander across the lane (and possibly into oncoming traffic), it sounds a warning.  Detecting lane markings is hard enough, but the real problem is distinguishing deliberate lane changes from unintentional ones.  Intersections and corners are treated as deliberate changes of direction. A turn signal also disables the warning.

 Networks have also come to automobiles.  Interprocessor networks are designed to cut down the long, tangled, complicated, expensive, and heavy wiring harnesses that permeate cars today.  Networks, of course, also enable processors to communicate amongst themselves.  The results are intended to be smarter, safer, lighter cars with simpler and more reliable wiring.

 The radio on many cars talks to the automatic transmission over an in-car network. Why? So the radio can automatically adjust its volume in  relation to road noise (which is a function of speed).  The airbag accelerometer, parking lights, GPS navigation, cell phone, and door locks also network so that in a serious accident, the car calls for emergency aid, sends the GPS coordinates of the accident, unlocks the doors, and flashes the car's lights.

 Among the popular standards are J1850 and CAN, with the latter gradually replacing the former.  Both buses provide low-latency, predictable performance, but neither is well suited to the high- bandwidth needs of toddlers in the backseat.  Minivans with DVD players and video games are adopting a separate "fun bus" for video and audio transport within the vehicle. FireWire and Media- Oriented Systems Transport (MOST) are two contenders.

 Side mirrors get a cue from the transmission so that when the driver shifts into reverse, the mirrors bend down and inward, the better to provide a view of what you're backing into.  This last feature was removed from a number of cars after thieves discovered that breaking off a mirror provided convenient access to the car's control network, including commands to unlock the car. (They could have just as easily reprogrammed the radio presets or reclined the passenger seat, but that's much less profitable to car thieves.)

 Longevity  While PC product cycles are measured in weeks or months, embedded processors for cars need to be around for five to ten years, minimum.  Extended temperature ranges.  Motorola rates its automotive-grade PowerPC 5200 from "40C to +85C. And that's just for dashboard and interior use.  For under-hood applications, the chips run reliably at 105C, even though at reduced clock frequency. You could literally fry an egg on top of the chip.

 Power  It would seem to be no problem in an automotive environment — even the wimpiest 80- horsepower engine generates almost 60,000 watts.  But no. While electrical current itself is no problem, the excess heat it generates is.  All microcontrollers generate some heat; a 32- bit RISC chip can easily draw five to six watts. (AMD's Athlon 3200+ consumes 76W.)  That kind of thermal energy is hard to dissipate from a cramped dashboard, engine bay.

 Pretty much anything you can think of.  In-car cameras to judge the presence, weight, and position of occupants for best airbag deployment. (Combined with wireless or cellular access this could create a strange webcam privacy issue — or a mixed blessing for parents with teenagers.)  Microprocessor-controlled solenoids may soon replace cams and valve lifters.  An Italian company is developing rearview mirrors with image-recognition that sense impending rear- end collisions

 Cars that talk with each other and drive on their own.  With this, cars can then receive their precise location in real time, monitor their stability control systems as well as their velocity and direction.  This information can then be passed to cars around them including those in ones projected path.  The challenge is to effectively calculate the probability of an accident, compare data between cars on the road and transmit detected threats to all involved cars.

 Last year, the Federal Communications Commission cleared the 5.9 gigahertz band for dedicated short range communication (DSRC) between cars and road side transceivers.  Cars may soon come with exterior airbags to protect pedestrians.

 Cars a few years from now will have the ability to self diagnose and pinpoint malfunctions or defective auto parts.  In the future, cars can also send a message to the driver via email when it detects any trouble in its engine.  Morphing Tire: wheels that can change shape according to its use. Those can be made using electro-active polymers that has the ability to change shapes with an electrical charge.

 It’s been twenty years since the first electronic systems began replacing critical mechanical components.  The easy stuff is done. It’s hard to argue against modern safety features — antilock brakes, for instance.  Many things still to be done. The journey has just begun !!!

Refrences  http://www.ercim.org/publication/Ercim_News/enw52/simonot -lion.html  http://www.acm.org/ubiquity/views/pf/v6i28_embedded.pdf  http://www.autopartsplace.com/car-technologies.htm  http://www.edn.com/article/CA46067.html  http://www.acm.org/ubiquity/views/pf/v6i28_embedded.pdf