25-08-2014, 10:37 AM
STREET LIGHTS THAT GLOW FOR 1/2KM ONLY ON DETECTING VEHICLE MOVEMENT PROJECT REPORT
STREET LIGHTS THAT GLOW.pptx (Size: 424.13 KB / Downloads: 36)
Abstract
The project is designed to detect vehicle movement on highways to switch ON only a block of street lights ahead of it (vehicle), and to switch OFF the trailing lights to save energy. During night all the lights on the highway remain ON for the vehicles, but lots of energy is wasted when there is no vehicle movement.
This proposed system provides a solution for energy saving. This is achieved by sensing an approaching vehicle and then switches ON a block of street lights ahead of the vehicle. As the vehicle passes by, the trailing lights switch OFF automatically. Thus, we save a lot of energy. So when there are no vehicles on the highway, then all the lights remain OFF. However, there is another mode of operation where instead of switching OFF the lights completely, they remain ON with 10% of the maximum intensity of the light. As the vehicle approaches, the block of street lights switch to 100% intensity and then as the vehicle passes by, the trailing lights revert back to 10% intensity again. High intensity discharge lamp (HID) presently used for urban street light are based on principle of gas discharge, thus the intensity is not controllable by any voltage reduction. White Light Emitting Diode (LED) based lamps are soon replacing the HID lamps in street light. Intensity control is also possible by Pulse Width Modulation (PWM) generated by the microcontroller. Sensors used on either side of the road senses vehicle movement and sends logic commands to microcontroller to switch ON/OFF the LEDs. Thus this way of dynamically changing intensity ON/OFF helps in saving a lot of energy. The project uses a PIC series microcontroller.
Further the project can be enhanced by using appropriate sensors for detecting the failed street light and then sending an SMS to the control department via GSM modem for appropriate action
Present day technology
White Light Emitting Diode (LED) based lamps are soon replacing the HID lamps in street light.
As these LEDs can switch faster than HID lamps we can apply PWM concept to these LEDs.
LEDs consume less power compared to HID lamps.
Life time of LEDs is also more.
Hardware requirements
TRANSFORMER (230 – 12 V AC)
VOLTAGE REGULATOR (LM 7805)
RECTIFIER
FILTER
PIC MICROCONTROLLER (PIC16F877A)
LEDS
PHOTODIODES
POTENTIAL DIVIDER
BC547
1N4007
RESISTORS
CAPACITORS
Description of power supply
The circuit uses standard power supply comprising of a step-down transformer from 230v to 12v and 4 diodes forming a Bridge Rectifier that delivers pulsating dc which is then filtered by an electrolytic capacitor of about 470microf to 100microF.
The filtered dc being un regulated IC LM7805 is used to get 5v constant at its pin no 3 irrespective of input dc varying from 9v to 14v.
The regulated 5volts dc is further filtered by a small electrolytic capacitor of 10 micro f for any noise so generated by the circuit.
One LED is connected of this 5v point in series with a resistor of 330ohms to the ground i.e. negative voltage to indicate 5v power supply availability.
Pic Microcontroller(PIC16F877A)
High-Performance RISC CPU:
• Only 35 single-word instructions.
• All single-cycle instructions except for program branches, which are two cycle.
• Operating speed: DC – 20 MHz clock input DC – 200 ns instruction cycle
• Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of Data Memory (RAM), Up to 256 x 8 bytes of EEPROM Data Memory.
• Pin out compatible to other 28-pin or 40/44-pin, PIC16CXXX and PIC16FXXX microcontrollers.
Special Microcontroller Features
100,000 erase/write cycle Enhanced Flash program memory typical.
• 1,000,000 erase/write cycle Data EEPROM memory typical.
• Data EEPROM Retention > 40 years.
• Self-reprogrammable under software control.
• In-Circuit Serial Programming™ (ICSP™) via two pins.
• Single-supply 5V In-Circuit Serial Programming.
•Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation.
• Programmable code protection.
• Power saving Sleep mode.
• Selectable oscillator options.
• In-Circuit Debug (ICD) via two pins.
PWM(Pulse width modulation)
The term duty cycle describes the proportion of on time to the regular interval or period of time; a low duty cycle corresponds to low power, because the power is off for most of the time.
Duty cycle is expressed in percent, 100% being fully on.
The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on, there is almost no voltage drop across the switch.
PWM works also well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle.
The longer the switch is on compared to the off periods, the higher the power supplied to the load is.
Photo diode
A photodiode is a type of photo detector capable of converting light into either current or voltage, depending upon the mode of operation.
Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fibre connection to allow light to reach the sensitive part of the device.
Operation of project
There are two basic modes of operation,
1. Transition of streetlights from dark to bright state.
2. Transition of streetlights from dim to bright state.
In the first mode of operation, when the vehicle is not present, all the streetlights will be in dark state. When a vehicle is sensed then the window of streetlights is illuminated in front of the vehicle.
Second mode of operation
In the second mode of operation, initially when the vehicle is not sensed, all the streetlights will be in dim state. This is achieved by use of pulse width modulation technique through the program stored in the microcontroller.
When a vehicle is not present on the highway, then the streetlights are made to glow for about 1ms and then for 100ms they are switched off. Thus, we get streetlights with less brightness.
When a vehicle is sensed, all the streetlights are illuminated for 1ms and the window of streetlights are illuminated for 100ms. Thus we have a PWM wave of 99% duty cycle.