04-10-2016, 02:13 PM
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ABSTRACT
In these days accidents are being happened due to carelessness of the drivers.So we thought of ‘AUTOMATIC HORN AND BRAKING’ system using sensors and other mechanisms. This will be effective in preventing the accidents mainly in highways. This project utilisepassive infrared sensors(PIR) of range 20m & 10m which detects the living beings on the road, hall effect sensor(speed sensor) which senses the speed of the vehicle. Initially the PIR sensor of 20m range is connected with the horn system. If it detects the living beingswithin its range,the output
voltage signal is sent to the amplifier and the horn system gets activated. Next in braking system, the PIR sensor of 10m range is connected with the speed sensor circuit. When PIR detects the living beings it activates the speed sensor circuit. The speed sensor will give the speed of the vehicle which in turn activate the relays. The speed limit is programmed in the microchip. If the speed is below 70km/hr one relay will be activated. When the speed is above 70km/hr two relays will be activated simultaneously. Based on the relay output, the speed of the motor varies.when the speed is high the voltage output will be more comparitively and the motor runs faster so the brakes will be applied suddenly. When the speed is low the voltage will be less and the motor speed is reduced, so the brakeswill be applied smoothly using rack and pinion mechanism.
INTRODUCTION
Day to day new advancements is taking place in automobiles. The new way of approach is to reduce the man power and to automate the system. We can use the advanced control equipments in order to automate the system effectively. Generally the design of automatic horn and braking system becomes more complex but it can be made easier and flexible by using sensors. The usage of sensors gives a voltage output which in turn activates the horn and braking circuit. Here two PIR sensors are used. One is connected to the horn circuit which gets activated on detecting the living beings within its range and it gets deactivated when the living things move away from its range. If suppose the living things still on its range then another sensor of 5m range is connected to the hall effect sensor which senses the speed of the vehicle and the output is given to the braking circuit which helps in actuating the braking system thereby preventing the accidents in a more efficient way.
Components description:
PIR sensor:
A passive infrared sensor is an electronic device that measures infrared light radiating from the objects in its field of view. PIR sensors are often used in the construction of PIR based motion detectors. Apparent motion is detected when an infrared source with one temperature such as human is passes in front of an infrared source with another such wall or atmosphere. This is not to say that the sensors sensor detects the heat from the object passing in front of it but that the object breaks the field which the sensor has determined as the "normal" state. Any object even one exactly the same temperature as the surrounding objects will cause the PIR to activate if it moves in the field of the sensors.
All objects above absolute zero emit energy in the form of radiation. Usually infrared radiation is invisible to the human eye but can be detected by electronic devices designed for such a purpose. The term passive in this instance means that the PIR device does not emit an infrared beam but merely passively accepts incoming infrared radiation. “Infra” meaning below our ability to detect it visually, and “Red” because this color represents the lowest energy level that our eyes can sense before it becomes invisible. Thus, infrared means below the energy level of the color red, and applies to many sources of invisible energy.
Hall Effect sensor:
A Hall Effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall Effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications. The sensor operates as an analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced. A Hall sensor is combined with circuitry that allows the device to act in a digital (on/off) mode, and may be called a switch in this configuration. Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustion engineignitiontiming, tachometers and anti-lock braking systems. They are used in brushless DC electric motors to detect the position of the permanent magnet.
Horn circuit working:
A 11m PIR sensor is used in horn circuit. When PIR sensor detects the living things within its range it will activate the horn. Initially power supply will be given to the PIR sensor and it will give a very small voltage output. When living beings cross the sensor then the output from that sensor will be high and it will activate the horn. The horn system will be continuously in ON condition until the living beings move away from the path. In some cases the output from the sensors will be low it can be amplified using the read switch. In our prototype we use the small buzzer as a horn which would operate in the 5v.
Braking circuit:
Tachometer is a device that gives you the information about the rotational speed of any shaft or disc. It usually measures the speed in revolutions per minute (RPM). Today we are going to make a simple tachometer that could measure the rotation speed of a disk without making any physical contact (that's why it is contact less) with the rotating object.
Reed switch:
The reed switch is an electrical switch operated by an applied magnetic field. It consists of a pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope. The contacts may be normally open, closing when a magnetic field is present, or normally closed and opening when a magnetic field is applied. The switch may be actuated by a coil, making a reed relay,[1] or by bringing a magnet near to the switch. Once the magnet is pulled away from the switch, the reed switch will go back to its original position.
Working:
The PIR sensor will give the information about the object the sensed signal will be given to the PIC pin RB0- Pin number 6 the pulse count from the read switch was given to Timer 0 external clock pulse it will count the RPM. It will check the difference between set RPM (600) and actual RPM from Timer 0 if the RPM is > = 600 relay 1 and Relay 2 will be turned ON or else relay 1 will be turned ON relay 2 will be turned OFF. If the above two condition not satisfied relay 1 and relay 2 both will be turned OFF.
Program:
unsignedint RPM;
sbit relay1 at RB1_bit;
sbit relay2 at RB2_bit;
sbit PIR at RB0_bit;
void main() {
TRISB = 0b00000001; // Set PORTB direction to be output
TRISA = 0b00110000; // Set PORTA direction to be output
PORTB = 0x00; // Turn OFF LEDs on PORTB
CMCON = 7 ; // Disable comparators
RPM = 0; // Initial Value of Counter
OPTION_REG = 0b00111000; // TOCS=1 for Counter mode, PSA=1 for 1:1
do {
TMR0=0;
Delay_ms(1000); // Delay 1 Sec
RPM = TMR0*60;
relay1 = 0;
relay2 = 0;
if((RPM >= 600) && (!PIR))
{
relay1 = 1;
relay2 = 1;
}
if((RPM < 600) && (!PIR))
{
relay1 = 1;
relay2 = 0;
}
} while(1); // endless loop
Advantages:
• Low cost
• Requires less space
• Suitable for all types of vehicles
• Prevent at least 20% of accidents
Conclusion:
According to the quote “Knowledge is power” we can make many impossible things as possible. By the waythis project is an innovative concept. It is more like an automatic driving. This system also acts like alerting the driver if there are any obstacles in the path. It is more of driver friendly. By implementing this concept we can reduce at least 20% if the accidents.