17-09-2016, 02:56 PM
1455166625-EMBEDDEDSYSTEMSAUTOMATIONOFCARS.doc (Size: 237 KB / Downloads: 4)
Abstract:
As you go about the affair of living, you put your life safe and luxurious with
all the available resources .Now days we all are entrenched with computers and
almost all depended on them. Devices with intelligence rule the world. Imbibing
intelligence to these devices is through a system called _EMBEDDED SYSTEM_.
Its applications provide marvelous opportunities for ingenious use of computer
technology. Almost all every system introduced into the market is an example of
Embedded System. An embedded device finds applications in all segments of
industrial and commercial marketplace. Home appliances, mobile phones, Personal
Digital Assistants (PDA), cars, tiny microchips and avionics are all using embedded
technology.
The current topic _Automation of car_ that we are going to present is one of
the fine examples of Embedded System.
There are many paradigm shifts taking place due to information explosion and
the concept of autonomous vehicle is one shift. The car, which is embedded, can
simulate the human driver completely and direct the vehicle on the road. Autonomous
vehicle has been the dream of scientists for long. Now their dream has come true as
with drastic changes in technical brilliance and developments in different fields with
EMBEDDED SYSTEM as pioneer.
Introduction
term embedded system is quite a complex one. Simply it is a
combination of hardware and software that forms the component of a larger system;
this in turn is programmed to perform a range of dedicated functions usually with a
minimal operator intervention. In embedded systems the hardware is normally unique
to a given application; computer chips are embedded into the control electronics to
manage the products functionality.
Embedded systems are rapidly becoming a catalyst for change in
computing data communications, telecommunications, industrial control and
entertainment sectors. New innovative applications in these as well as other areas
such as home networking and car infotainment will roll out in the near feature.
In present Arena every thing is going compact and adaptable. More over
continuing trends in Microelectronic Technology and its integration begins to alter
the ground rules in the design of high performance systems, such as Embedded
Systems. Those Embedded Systems and Real Time Operating Systems (RTOS) are
part-achieving, ubiquity, blurring the lines between science fiction and hard reality
The main idea behind these Embedded Systems is _why to use a hammer
when a gentle touch would do_.
Embedded Systems exists in wide variety of fields from automated vending
machine to complex embedded systems that controls aircraft functions. This paper
mainly contains the design concepts; development process of Embedded Systems and
the Hardware architecture containing processor, Memory and other Hardware devices
has been discussed briefly. Recent trends, applications and the explanation developing
this embedded system technology. This Embedded System technology may one day
result in such a comfort for human, so that he could live in an intelligent home and
make his health undisturbed
Embedded Systems are combinations of hardware and software that are
mounted on compact electronic circuit boards integrated into the devices. They are
engineered or intended to perform one specific function in a specific environment. An
embedded system is a special-purpose computer system built into a larger device,
typically required to meet very different requirements than a general-purpose personal
computers.
Programs on an embedded system often must run with real-time constraints.
Real-time computing is that type of computing in which correctness of the system not
only depends on logical result of computation but also on the time at which the results
are produced. Usually there is no disk drive, operating system, keyboard or screen in
an embedded system.
Most embedded systems are small enough to sit on the end of a thumb and are
usually hidden within much larger and more complex mobile computing or electronic
devices, so they often go unnoticed. But embedded systems actually represent the vast
majority of semiconductor sales. According to an estimate, there are 5 billion
embedded microprocessors in use today.
Embedded Systems
An embedded system employs a combination of hardware &
software (a _computational engine_) to perform a specific function; is part of a larger
system that may not be a _computer_; works in a reactive and time-constrained
environment.
Software is used for providing features and flexibility
Design of embedded systems:
One important decision in the design of an embedded system is the selection
of the processor(s) around which the rest of the system is to be built. The electronics
usually uses either a microprocessor or a micro controller. Some large or old systems
use general-purpose mainframe computers or minicomputers
Embedded Processor:
An Embedded Processors is simply a microprocessor that has been
_Embedded_ into a device. It is software programmable but interacts with different
pieces of hardware and performs both control and computation. It gives more
performance than a micro controller but not as much performance as a general-
purpose processor. They are used in cars, phones, media devices, wireless, and
printers
Technology:
There are many new technologies being implemented for the designing of the
embedded systems.
Processor technology:
It is the architecture of the computation engine used to
implement a system_s desired technology. Processors vary in their customization.
They need not have to be programmable.
It_s the manner in which a digital (gate-level) implementation is
mapped onto an IC. IC technologies differ in their customization to a design and with
respect to who builds each layer IC_s consist of numerous layers (perhaps 10 or more)
Types are: Full-custom/VLSI, Semi-custom ASIC (gate array and standard cell), PLD
(Programmable Logic Device).
Design Technology
The manner in which we convert our concept of desired system functionality into an
implementation
Design Criteria of embedded processors:
The three most important design criteria are performance, power, and cost.
Performance:
Performance is a function of the parallelism, instruction encoding
efficiency, and cycle time.
Power:
Power is approximately a function of the voltage, area, and switching
frequency. It_s also a function execution time for leakage.
Cost:
Cost is a function of both area (how many fit on a die) and
The complexity of use (in terms of engineering cost)
The fine art of automation:
Just imagine. We load the code of our destination in the dashboard
computer and turn the car on, while we remain seated carefree on the rear seats. Then
its all the job of the _unknown_ to drive it on the roads, bridges, thought the bazaars,
past the crossings to the destination, without getting challenged even once for traffic
rule violations.
A fully computerized car capable of doing almost every thing a car lover
would want to. Seems like fantasy but a day is not far when almost all automobiles
will interact with computer on dashboards. From ordering pizza to booking tickets at
the nearest theatre, things would be as easy as giving orders to your servant. As a
matter of fact, vehicles all over the world are now fitted with intelligent devices that
make the vehicles to respond to various factors _be it climate control, sudden
accelerations or braking or even self-repair of modules.
There are trends where the finger print technologies are also have been
introduced which gives the following reliabilities You could one day be able to enter
and start your car with the touch of a finger. And that same touch, with your
fingerprint acting as a key, would trigger a check of the mirrors, steering wheel, radio
and temperature to ensure that they're the way you like them. The convenience of
fingerprint recognition technology comes with heightened security. Unlike personal
identification numbers, passwords and keys, each person's unique fingerprints can't be
duplicated, lost or forgotten.
Description:
As stated above that a vehicle can run by itself with out the intervention
of human beings by the embedded intelligence in it. For this purpose Global
Positioning System (G.P.S) using satellites can provide positioning information and
proves to be a versatile all-time. For still higher accuracy wide area differential GPS
is used, which offers a robust system that readily deals with selective availability
errors and satellite clock errors.
An error level of decimeter/centimeter is guaranteed by WADGPS. This
satisfies the ground vehicle control algorithm. Human intervention is completely
eliminated by using of reliable sensors and actuators. Making the overall performance
of transporting system both congestion-free and collision incorporate the concept of
WADGPS they_re _free, besides making it cost effective.
The models for GPS also include aiding sensors, e.g. dead reckoning,
radar and camera. A computer is simply required to feed destination into a dashboard
computer. Highly sensitive actuators simulate a human driver completely and direct
the vehicle on the road. The vehicle transmitter broadcasts its position and velocity to
other immediate participants for collision-avoidance and lane changing manoeuvres.
Forward and reverse motions and u-turns are precisely achieved as per route guidance
requirements. Furthermore, an accurate steering control is obtained using Pulse Code
Modulation technique and acceleration/braking control is successfully implemented
using learning adaptive system.
The simplest form of vehicle navigation employs a heading sensor,
velocity sensor and a processor. Typically a navigation system requires an input of
initial position and it self-initializes the heading sensor with respect to north. The
processor then integrates the velocity sensor output to determine distance traveled and
resolves the heading sensor data to calculate a new position. This reckoning
navigation requires additional vision sensors, route guidance and map-matching
algorithms for making the driving tasks fully automatic.
The remarkable advances in microelectronics and data processing technology have
made possible the miniaturization of sensors the integration and combination of data
from a number of sensors. Television cameras, charge coupled device (CCD) type
sensors, laser radar and infrared sensors ma be used.
The reliability, efficiency and cost effectiveness of an autonomous
vehicle depend mainly on how judiciously its navigation sensors, perception unit and
computer control is incorporated and how well their performance meets today_s
transportation needs. Quite of ten a human driver is forced to maintain attention for
long periods of time and commit to unpredictable contingencies on the free ways
together with traffic jams. All this leads to fatigue and hypo vigilance at the wheel and
consequently to more frequent collisions and congestion.
The driver_s activity
is influenced by several factors
that depend on driver itself and
is environment such as traffic
density, traffic status, time of
travel and weather. Thus the
driving activity deals with a
combined driver vehicle-
environment system shown in
figure
The vehicle is
required to blend its environmental
perception capabilities with its
intelligent controls in order to
affect optimal path-planning strategies that not only avoid obstacles but also minimize
criteria such as time of travel, fuel consumption, exposure to pollution/danger, etc.
however basic driving functions consists of lane-keeping, safe distance maintenance,
The vehicle transmitting system continuously provides information about
its position and velocity to its participants. A safe distance with respect to its
immediate surroundings is maintained by acceleration/brakes and steering controls.
The internal platform and rate gyro and accelerometer package keeps the vehicles
central processing unit (CPU) well informed about the incremental changes in the
vehicles parameters. The wheel odometers provide the vehicle traveling distances by
multiplying the number of electronically generated pulses by a constant, depending
upon wheels perimeter
As the actual tyre size is influenced by vehicles speed, tire pressure play load and
atmospheric conditions, appropriate corrections are maid by the CPU. The
atmospheric data system keeps continuous record of outside atmospheric temperature,
pressure and differential pressure.
The information concerning deviation from the road center is obtained
by magnetic as well as optical sensors, and fed to the CPU. The GPS receiver updates
the vehicles position and velocity to centimeter/decimeter levels as required for the
lateral or longitudinal control actions. The autonomous vehicle embedded software
mission finally yields the estimates for throttle and
Heading angle increments for a safe and accident free Maneuvers. The following
figure gives an indication of all the technologies used in a car