1. SENSORS
A sensor is a device that measures a physical quantity and converts it
into a signal which can be read by an observer or by an instrument.
Sensors are used in everyday objects such as touch sensitive elevator
buttons and lamps which dims or brighten the light by touching the
base.
Applications can includes cars, machines, aerospace, medicine,
manufacturing and robotics.
2. PIR SENSOR
Operating principle:
• All objects with a temperature above absolute zero emit heat
energy in the form of radiation.
• Usually this radiation is invisible to the human eye because it
radiates at infrared wavelengths, but it can be detected by electronic
devices designed for such a purpose.
3. The term passive in this instance refers to the fact that PIR
devices do not generate or radiate any energy for
detection purposes.
They work entirely by detecting the energy given off by
other objects. PIR sensors don't detect or measure "heat";
instead they detect the infrared radiation emitted or
reflected from an object.
4. Infrared radiation exists in the electromagnetic
spectrum at a wavelength that is longer than visible
light.
It cannot be seen but it can be detected.
Objects that generate heat also generate infrared
radiation and those objects include animals and the
human body whose radiation is strongest at a
wavelength of 9.4μm.
Infrared in this range will not pass through many types
of material that pass visible light such as ordinary
window glass and plastic
.
5. However it will pass through, with some attenuation,
material that is opaque to visible light such as
germanium and silicon.
An unprocessed silicon wafer makes a good IR
window, It provides additional filtering for light in the
visible range. 9.4μm infrared will also pass through
polyethylene which is usually used to make Fresnel
lenses to focus the infrared onto sensor elements.
6. This sensor is made of a crystalline material(also known as sensor element)
that generates a surface electric charge when exposed to heat in the form
of infrared radiation.
When the amount of radiation striking the crystal changes, the amount of
charge also changes. The sensor elements are sensitive to radiation over a
wide range so a filter window is added to limit detectable radiation to the 8
to 14μm range which is most sensitive to human body radiation.
Typically, the FET source terminal pin 2 connects through a pull down
resistor of about 100 K to ground and feeds into a two stage amplifier
having signal conditioning circuits.
The amplifier is typically bandwidth limited to below 10Hz to reject high
frequency noise and is followed by a window comparator that responds to
both the positive and negative transitions of the sensor output signal.
The PIR325 sensor has two sensing elements connected in a voltage
bucking configuration. This arrangement cancels signals caused by
7. A body passing in front of the sensor will activate first
one element
and then the other, whereas other sources will affect both
elements simultaneously and be cancelled.
Fresnel lens is made of an infrared transmitting
material design to focused an infrared radiation onto
sensor element as can be shown below
10. What do we mean by ‘Intelligent
lighting’?
Compared with a conventional lighting system, a
system where every light has a manual switch or
dimmer that you must operate directly, ‘Intelligent
lighting’ can be as simple as automating a single
light, so that it can be controlled by a
remote control device or timer.
11. Why do we need Intelligent lighting system?
19% of energy use in the world is used for lighting, and 6% of
greenhouse emissions in the world derive from this energy used for
lighting
Intelligent lightning is the good way which enables to minimize and
save light by allowing the householder to control remotely cooling
and heating, lighting, and the control of appliances. This ability saves
energy and provides a level of comfort and convenience.
The concept of Intelligent lighting also involves utilizing natural light
from the sun to reduce the use of man-made lighting.
Lighting control systems serve to provide the right amount of light
where and when it is needed.
12. Daylight Dimming
Daylight Diming controls the artificial light
depending on the available daylight.
When enough daylight is available, the
artificial light dims down according to how
much light is available.
With the common light fitting , Photo
sensor elements are integrated in the
ceiling.
13. Applications
• Office- In offices, we can use day dimmer instead of operating
switches multiple times in a day.
14. Applications
• Street light- We can use day dimmer in street lighting to automatically
dim the light in early hours.
15. Occupancy sensors
Occupancy sensors / presence detectors are a
special type of motion sensors. It automatically
turns lights on when a room is occupied and off
when a room is vacant.
They are specifically designed to pick up small
movements in demanding applications such as
tunnels.
Methods of intelligent lighting
19. Methods of intelligent lighting
Wireless lighting
In Wireless control system, all lamps are connected in a wireless
network allowing them to be controlled from remote controls, wall
switches or internet connected devices.
35. #include<Servo.h>
Servo myservo;
int led=6;//Arduino pin connected to LED
int pir=2;//Arduino pin connected to motion sensor's pin
void setup()
{
pinMode(pir,INPUT);//set arduino pin to input mode
pinMode(led,OUTPUT);// set arduino pin to output mode
myservo.attach(9);// attaches the servo on pin 9 to the servo object
Serial.begin(9600);//initialise the serial
}
void loop()
{
int val= digitalRead(pir);
Serial.println(val);
if(digitalRead(pir)== HIGH)
{
digitalWrite(led,HIGH);
myservo.write(70);
}
else
{
digitalWrite(led,LOW);
myservo.write(10);
36. A Tilt Sensor switch is an electronic device that detects
the orientation of an object and gives its output High or Low
accordingly. Basically, it has a mercury ball inside it which
moves and makes the circuit. So tilt sensor can turn on or
off the circuit based on the orientation.
Tilt Sensor
37. This is a Mercury switch based tilt sensor module that gives high at
its output pin when tilted. It requires a 5V of DC input.
It’s a three-terminal device consist of input, ground, and output.
It has a glass tube consist of two electrode and liquid mercury ball.
The liquid mercury ball closes and opens the circuit when inclined
in a particular direction.
The working and internal structure of the module is given below:
Tilt Sensor
38. Working of Tilt Sensor
CASE 1: NOT TILTED
Initially, when it is in NOT tilted position as shown in the image
below, it gives LOW output because of the liquid mercury
complete the circuit by connecting the two electrodes. When
the output is LOW on-board LED remain ON.
39. CASE 1: TILTED
When it is inclined in a particular direction or angle, the liquid mercury
breaks the contact between the metal electrodes and the circuit gets
open. Hence, we get HIGH output in this condition and the onboard
LED turns off.
40. Applications of Tilt Sensors
•Cameras.
•Video Cameras.
•Aircraft Flight Controls.
•Construction Equipment.
•Robotic Technology.
•Automobile Air Bags.
•Videos Game Controllers.
•Studying Human Movement.
41. To connect a Tilt sensor with the Arduino, it requires 5v dc
input to operate. That 5v is supplied using Arduino UNO and the
output of Tilt sensor is taken at PIN 4 of the Arduino. LED is
connected with the PIN 2 of the Arduino UNO with 220-ohm
resistor to limit the current to a safe value. And, the buzzer is
directly connected to the PIN 3 of the Arduino UNO.
