24-11-2012, 12:26 PM
A NOVEL REAR END COLLISION & ACCIDENT AVOIDANCE SYSTEM WITH DYNAMIC SPEED GOVERNOR
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ABSTRACT
Automotive vehicles are increasingly being equipped with collision avoidance and warning systems for predicting the potential collision with an external object, such as another vehicle or a pedestrian. Upon detecting a potential collision, such systems typically initiate an action to avoid the collision and/or provide a warning to the vehicle operator. This system consist of a distance-measuring system based on ultrasonic sound utilizing the PIC 16f877A microcontroller and transmits a burst of ultrasonic sound waves towards the target and then receives the corresponding echo. An ultrasonic sound sensor is used to detect the arrival of the echo to the system. The time taken for the ultrasonic burst to travel the distance from the system to the subject and back to the system is accurately measured by the microcontroller. It also provides a warning signal to the driver if the distance between vehicle and obstacle crosses a particular limit. It also monitors the speed of the vehicle and if the speed limit is exceeded it is informed to the driver. The speed limit for different class of vehicles is set by authorities at different.
INTRODUCTION
This report describes a distance-measuring system based on ultrasonic sound utilizing the PIC 16f877A microcontroller. With the help of the distance measured, the micro-controller will make the vehicle stop suddenly if the vehicle is about to hit any obstacle or any other vehicle. With the help of this technology accidents are avoided. The system transmits a burst of ultrasonic sound waves towards the target and then receives the corresponding echo. An ultrasonic sound sensor is used to detect the arrival of the echo to the system. The time taken for the ultrasonic burst to travel the distance from the system to the subject and back to the system is accurately measured by the microcontroller. Different types of vehicle speed limiters are in current use for regulating traffic especially across roads near populated areas such as hospitals, malls and schools. This project “DYNAMIC SPEED GOVERNER” is a new method by which vehicle speed is controlled externally rather than internally. The speed measurement and control is accomplished via two PIC16F877As with a RF transmitter and a receiver.
SOFTWARE SPECIFICATION MPLAB IDE MPLAB Integrated
Development Environment (IDE) is a free, integrated toolset for the development of embedded applications employing Microchip‟s PIC and dsPIC microcontrollers. MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use and includes a host of free software components for fast application development and supercharged debugging. MPLAB IDE also serves as a single, unified graphical user interface for additional Microchip and third party software and hardware development tools. Moving between tools is a snap, and upgrading from the free software simulator to hardware debug and programming tools is done in a flash because MPLAB IDE has the same user interface for all tools. A development system for embedded controllers is a system of programs running on a desktop PC to help write, edit, debug and program code- the intelligence of embedded systems applications in to a microcontroller. MPLAB IDE, runs on a PC and contains all the components needed to design and deploy embedded systems applications. MPLAB IDE Programmer‟s Editor helps write correct code with the language tools of choice. The editor is aware of the assembler and compiler programming constructs and automatically “color-keys” the source code to help ensure it is syntactically correct. The Project Manager enables you to organize the various files used in your application source files,processor description header files and library files.
How MPLAB IDE Helps
The organization of MPLAB IDE tools by function helps make pull-down menus and customizable quick keys easy to find and use. MPLAB IDE tools allow us to Assemble, compile, and link source code. Debug the executable logic by watching program flow with the simulator, or in real time with the MPLAB-ICE emulator. Make timing measurements, view variables in watch windows, program firmware with PICSTART Plus or PRO MATE II, find quick answers to questions from the MPLAB IDE on-line Help and much more.
CCS C COMPILER
The compiler contains Standard C operators and built in libraries that are specific to the PIC registers. Access to hardware features from C. The compiler includes built-in functions to access the PIC microcontroller hardware such as READ_ADC to read a value from the A/D converter. Discrete I/O is handled by describing the port characteristics in a PRAGMA. Functions such as INPUT and OUTPUT_HIGH will properly maintain the tri-state registers. Variables including structures may be directly mapped to memory such as I/O ports to best represent the hardware structure in C. The microcontroller clock speed may be specified in a PRAGMA to permit built in functions to delay for a given number of microseconds or milliseconds. Serial I/O functions allow standard functions such as GETC and PRINTF to be used for RS-232 like I/O. The compiler runs under Windows 95, 98, ME, NT4, 2000, XP, Vista or Linux. It outputs hex and debug files that are selectable and compatible with popular emulators and programmers including the MPLAB IDE for source level debugging.
LITERATURE REVIEW
The new speed limiting system presented in this project combines several pioneering techniques that integrate wireless technologies in order to implement a reliable speed control system. This proposed system can be easily implemented near different populated areas. The power of the proposed system lies in its flexibility and capability of development with little hardware changes such as changing the speed limits and speed control methods using the software of the base station in negligible amount of time. The proposed system is based on microcontroller technology for collecting data related to speed and transmitting it through a transceiver to a base station that analyzes the transmitted data and takes appropriate decisions related to speed limit and control requirements. Speed Governor regulates the top speed and/or maximum rpm of a vehicle, whether it is electronically or mechanical. The governor is emplaced by the manufacturer to meet laws of the nation is which the vehicle will be sold, protect the drivers from operating at unsafe speed, or to protect the car from being driving beyond its physical or mechanical threshold.
MICROCONTROLLER
PIC 16F877A The microcontroller is a set of digital logic circuits integrated on a single silicon „chip‟ whose connections and behavior can be specified and later alter when required, by the program in its memory. The great advantage of this is that in order to change the circuit‟s structure and operation, all that is needed is a change in the program very little, if any, circuit hardware modifications are necessary. The microcontroller unit used here is a PIC16f877A .The core controller is a mid-range family having a built-in SPI master. 16F877A have enough I/O lines for current need. It is capable of initiating all intersystem communications. The master controller controls each functions of the system with a supporting device. Also responsible for reception of commands from the host and taking necessary actions. PIC16F877A is an 8-bit, fully static, EPROM/EPROM/ROM-based CMOS microcontroller. It employs RISC architecture with only 35 word/single cycle instructions. All these instructions are single cycle (1ms) expect for program branches which takes two cycles. The PIC16f877A products are supported by a full featured macro assembler, a software simulator, „C‟ compiler etc.
DATA MEMORY ORGANIZATION
The data memory is partitioned into multiple banks which contain the General Purpose Registers and the Special Function Registers. Bits RP1 (STATUS<6>) and RP0 (STATUS<5>) are the bank select bits. Each bank extends up to 7Fh (128 bytes). The lower locations of each bank are reserved for the Special Function Registers. Above the Special Function Registers are General Purpose Registers, implemented as static RAM. All implemented banks contain Special Function Registers. Some frequently used Special Function Registers from one bank may be mirrored in another bank for code reduction and quicker access. I/O PORTS Some pins for these I/O ports are multiplexed with analternate function for the peripheral features on the device. In general, when a peripheral is enabled, that pin may not be used as a general purpose I/O pin. Additional information on I/O ports may be found in the PICmicro™ Mid-Range Reference Manual (DS33023). PORTA and the TRISA Register PORTA is a 6-bit wide, bidirectional port. The corresponding data direction register is TRISA. Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., put the contents of the output latch on the selected pin). All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, the value is modified and then written to the port data latch. Pin RA4 is multiplexed with the Timer0 module clock input to become the RA4/T0CKI pin. The RA4/T0CKI pin is a Schmitt Trigger input and an open-drain output. All other PORTA pins have TTL input levels and full CMOS output drivers. Other PORTA pins are multiplexed with analog inputs and the analog VREF input for both the A/D converters and the comparators