ultrasonic car parking

ULTRASONIC CAR PARKING ASSISTANCE

INTRODUCTION: In highly populated areas it can be difficult to find available parking spots. In addition to traffic rushing by and multiple drivers competing for the same space, another challenge is that parking spaces are tight and difficult to manoeuvre into. This paper presents design and implementation of a system called “Parking Assistance” The Parking Assistance can be used as a tool to help people with disability, beginner drivers, and even just for the fun of it. When a driver wants to park, he or she switches the system ON to start the parking process. Ultrasonic sensors are used to calculate the distance from the back bumper of the car. After that the driver is informed through LCD screen and buzzer to stop the car and follow the steps which lead him or her to park the car in the parking space safely and with minimum effort. In addition, the device gives the driver a warning message when the vehicle gets too close to other objects in the parking space. Presently, the detection technique of laser, radar, infrared ray and ultrasonic have been widely applied at the aspects of safety technique of car collision avoidance and distance measurement. At the aspect of collision avoidance laser, radar and infrared ray are commonly applied to measure the control range between two cars and the range which should be measured behind the car. At the aspect of distance measurement the technique of ultrasonic is applied to measure the detection range when a car change the driveway and to detect the obstruction behind the car when backing up or parking. Because of the expensive price, the distance measurement system of backing up with the technique of laser and radar is only set on the minority of slap-up cars, so the research of the distance measurement system of backing up with high ratio of capability and price for the medium cars and the low-end cars is an important task of auto-electron industry.

SOFTWARE AND HARDWARE TOOLS USED: Software tools: 1) ISIS Proteus Simulator 2) ISIS Proteus PCB Designer 3) MPLAB v8.80 Hardware Components: 1) 2) 3) 4)

PIC16F877A ECHO “SEN1156” Ultra Sound Sensor. Buzzer LCD

BLOCK DIAGRAM:

BLOCK DESCRIPTION: 1. Ultrasonic Sensor: This "ECHO" Ultrasonic Distance Sensor provides very short (2 cm) to long-range (4 m) detection and ranging. The sensor provides precise, stable noncontact distance measurements from 2cm to 4 m with very high accuracy. Its compact size, higher range and easy usability make it a handy sensor for distance measurement and mapping. The board can easily be interfaced to microcontrollers where the triggering and measurement can be done using one I/O pin. The sensor transmits an ultrasonic wave and produces an output pulse that corresponds to the time required for the burst echo to return to the sensor. By measuring the echo pulse width, the distance to target can easily be calculated. 2. PIC16F877A – ULTRASONIC Interface: As per the figure, the signal I/O pin of the ECHO sensor is to be connected to RB2 (Pin) of the HOST controller. Pin RB2 of the host controller has to be configured to both input and output accordingly to the function. It is thehost controller that has to trigger the functioning of an ECHO senor. At this time the pin RB2 of the host controller has to be configured as output so that it can give (o/p) a trigger signal to the sensor. The trigger pulse should be of range 10μsec - 100μsec, typical value is 10μsec. After triggering the sensor, pin RB2 has to be configured as input so that the host controller switches to the receiving mode. Any pin configured as input should be provided with either pull-up or pull-down voltages so that it isn’t affected by small static field variations. But here no external pull-ups or pull-downs are required since, the signal I/O pin of the ECHO sensor which is to be connected to pin RB2 has been provided with pull-down onboard. In the receiving mode, the host controller has to wait for the Low to High transition in the signal pin. When a transition is detected, the host controller should start counting the time. The host controller can use a timer or any other programming logic to calculate the time. The counting should terminate when the next high to low transition is detected. The time gap between transitions will vary (PWM)with respect to the distance to the target. The obtained value (pulse-width) in micro seconds represents the echo time and further calibrations of this data gives the obstacle distance, that is, the echo time in micro-seconds divided by 58 (at 30° C) gives you the obstacle distance in centimetres and the same divided by 148 (at 30° C) gives

the distance in inches, that is (echo time in μsec) /58 = distance in cm.The calculated distance can be used for further computations.

Speed of ultrasonic wave = 0.0347cm/us Time=(2*Distance)/velocity =(2*Distance)/0.0347cm/us Time=Distance/58 3. PIC16F877A - BUZZER Interface: The microcontroller computes the distance to the obstacle and uses the buzzer to indicate the relative distance the obstacle. The microcontroller actually generates sound with different intensities based on the distance using a software generated PWM. The intensity is maximum when the distance to the obstacle is less than 20cm. The intensity is decremented for every further 20 cm and is minimum when the obstacle is at a distance equal to and more than 100cm (1 meter). The buzzer remains inactive if the obstacle is at a distance more than 1 meter.

4. PIC16F877A- LCD Interface: The LCD is used to give an indication to the driver how much distance is remaining. Based on the change in distance the LCD screen will provide an indication. Modern car LCD screens can be built small enough to fit almost anywhere in the vehicle. LCD screens are the industry standard when it comes to in-vehicle entertainment. They are used in car DVD players, navigation devices and vehicle display systems. Recent developments in LCD technology have allowed for screens to be incredibly small and still provide a sharp, clear picture. LCD data port is connected to the PORTD of PIC16F877A. The VCC pin of LCD is given to microcontroller power supply. The RS pin is given to RB4 pin of host controller. The EN pin of LCD given to RB5 of host controller. VSS, R/W pin connected to ground. The VEE pin connected to potentiometer and is used to control the brightness os LCD.

CIRCUIT EXPLANATION The circuit have 4 sections 1. Power Supply Section 2. Micro controller Section 3. Sensor Section 4. Output Section

A DC regulated supply of 0-30V power supply is used as the main power source. A voltage regulator circuit based on a 7805 IC is user to make a regulated 5V supply. The micro controller used is PIC16F877A. The ultra sound sensor produces output corresponding to the distance to the obstacle. This output is fed to the micro controller through RB2. The output section has a buzzer, which is programed in such a way that it produces different tones depending on the distance to the obstacle.

CIRCUIT DIAGRAM

CIRCUIT LAYOUT

CONCLUSION: The objective of this project was to design an economical and reliable parking helper using ultrasound technology which could easily be incorporated either during car manufacturing phase or installed by the automobile owner using simple tools. We have been successful in achieving not only this objective but have also been able to add an extra feature into the circuit design, i.e., buzzer, which can be very helpful to those who cannot read from the LCD screen for any reason. The designed parking helper works best when the vehicle to be parked is travelling at speed between the range 5-10 Km/h which is a logical speed at which the vehicle must be moving if it requires to be parked. To increase this speed range will require extra number of high-speed sensors which will increase the cost and complexity of the design.