Car speed Detector Project
In this project I am going to show you how to measure the speed of running car (or man) from outside. Police department uses this type of system to prevent over speed of vehicles. Our project is a little different from the system used by police but the overall car speed detector concept is same.
In this project, two IR sensors are placed apart on one side of road. When any vehicle crosses the sensors, the internal timer of Arduino counts the time between activation of sensor. Now speed is measured by using simple distance time relationship.
Both IR sensors are connected to the interrupt pin of Arduino, and they detect the falling wave. The purpose of using interrupt is that, it improves the efficiency of system.Â A LCD is connected to Arduino and measured speed is shown on LCD.
When car moves in front of the first sensor, it gives the output signal to Arduino, Arduino detects the falling wave, now internal timer of Arduino is started and when car moves in front of second sensor timer is stopped.
Now Arduino measures the speed of car which is measured by distance time relationship
Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Speed = Distance Ã· TimeÂ
- Speed: Car’s speed
- Distance: Distance between sensors
- Time measured by Arduino
The IR sensor includes an IR LED and a phototransistor. When an object passes between the sensors, light reflects from the object and falls on the phototransistor. An operational amplifier IC (LM358) is used and the phototransistor is connected to it. When object come in front of sensor, it sends a logical HIGH signal to Arduino.
An Arduino Nano is used as the controlling unit, You may use any other Arduino variants according to your choice.
|Power Adaptor||12 Volt||1|
Car Speed Detector Circuit
Circuit diagram is shown in the figure below. If you are going to make circuit on breadboard or general purpose PCB (or Zero PCB), the figure below is useful.
For PCB etching,
In the Arduino pins D2 and D3 are interrupt, where D2 is INT0 and D3 is INT1. Output pins of the IR sensors are connected to these pins.
LCD is connected to Arduino’s D4 to D9 pins, where D4 is connected to EN, D5 is connected to RS and D6 to D9 of Arduino are connected to D4 to D7 pin of Arduino. A preset is connected to third pin of LCD, which is contrast control. Pin 15 and 16 are used for backlight of LCD.
At the beginning of the code a header file is declared by name â€œLiquidCrystal.hâ€, which is used for LCD display. In the next line pins of LCD are declared in the function “LiquidCrystal lcd(4,5,6,7,8,9)”, number in the bracket shows the pins of Arduino that are connected to the LCD.
In the line 4 and 5 two integers are declared by the name sensor1 and sensor2, these are pins of Arduino pins which are connected to IR sensors.
After it 4 integers are declared by name Time1, Time2, Time, and flag. Where â€œTime1â€ is the measured time when â€œsensor1â€ is activated and â€œTime2â€ is the measured time when â€œsenaor2â€ is activated. The integer Time is the difference of “Time1” and “Time2”, which is equivalent to time taken by car to go from “sensor1” to “sensor2” or “sensor2” to “sensor1”
Now a float is declared by name “Speed” that is measured speed of the running car.
At the starting of â€œvoid setup()â€ two interrupts are attached by function “attachInterrupt(0, fun1, Falling)â€ that means when â€œinterrupt0 (INT0)â€ detect the falling wave, fun1 will run.
Now the LCD is begins by using “lcd.begin(16,2)” Â function. LCD is cleared by using the â€œlcd.clear()â€ function and “SPEED MEASUREMENT” is printed on the LCD by using function “lcd.print”
In the â€œvoid fun1()â€ will run when â€œinterrupt0 (INT0)â€ activated, in this function current time is measured by using “Time1 = millis()”. After it an â€œif elseâ€ condition is used, it makes the â€œflagâ€ 1 when it is 0 and makes 0 when it is 1.
After it â€œvoid fun2()â€ is used, that is the exact same as Â â€œvoid fun1()â€ but it runs when â€œinterrupt1 (INT1)â€ is activated.
In the â€œvoid loop()â€ first of all Time is measured by using â€œTime1â€ and â€œTime2â€, the â€œTimeâ€ should be positive so “if else” is used for making it positive. But this loop runs when flag is equals to zero so an “if” condition is used. If “Time1” and “Time2” are equals “Speed” will be zero.
In the line 47 an condition activated when speed is equals to zero, at this time “….OK….” is printed on second raw of LCD, that indicates, system is ready to use.
In the line 51 speed is printed on LCD after printing “Time1” and “Time2” will become zero.
In the measurement of speed distance, time relationship is used. So distance between sensors is very important, so we need to calibrate the system.
In the line an integer is declared by name distance that is equal to 27, this is the distance between both sensors. This distance can be varying according to your arrangement, so measure the distance in Centimeter and change here.