Motion Detectors

8/8/2019 Motion Detectors

1/21

MOTION DETECTORS


2/21

Introduction In the 1800s, a German physicist sat at his work

table, studying the effect of radio waves on

different materials. Suddenly, he had anepiphany. He discovered that some of thewaves were able to pass through certainmaterials, while some materials reflected back

the radio waves. He quickly collected data onthis research, which led to the development ofradio, and eventually became the foundationfor radar technology.


3/21

This physicist was named

Heinrich Hertz, and he isthe man that made todays

motion detectingtechnology possible.


4/21

What is a motion detector?

A motion detector is an

electronic device that detectsthe physical movement in agiven area and transformsmotion into an electric signal.


5/21

5 Types of Motion Detectors

Infrared Detectors (IR)

Radar-based Motion DetectorsUltrasonic Motion Detectors

Digital Motion DetectorVibration Motion Detector


6/21

Active Infrared Motion Detector (IR)

uses an IR sensor, as well as a source ofradiation.

The sensor is able to detect interruptions in

the radiation it receives from the radiationsource.

able to detect the signal of heat energy

emitted by an intruder as it differs from theconstant infrared scanning activity of thedetector, as long as the intruder passesthrough its detection range.


7/21

The simplest typeof active motiondetector iscommonly usedin commercialdoorways totrigger adoorbell.

used at grocerystores toautomaticallyopen the doorsfor customers


8/21

Passive Infrared Motion Detector (PIR) A PIR sensor is able to use an optical collection

system in combination with several differentsensing elements. This allows the sensor to detectany changes that occur in ambient infrared

radiation. The sensor is able to recognize a thermal infraredimage (created by infrared technology combined

with a heat sensor), which usually starts thetransmission of an alarm signal back to the units

receiver. PIR emits nothing. As its passive name suggests,it responds only to infrared energy radiated bythe object being sensed. The most commonobject a PIR sensor detects is the human body


9/21

PIR Applications perhaps the most frequently used home security

device

commonly used in conjunction with outdoor light

fixtures and indoor light switches to turn on alight

also used to conserve electricity

When used as fire detectors, the passive IR sensors

are coupled to a circuit which monitors the rateof increase in ambient temperature. If the rate ofincrease in ambient temperature is above acertain preset value, a fire warning is activated.


10/21


11/21

Continuous Wave Radar Motion

Detector (CW)

use microwave signals to emit frequencies tobounce off of the surrounding area (which is

why they are sometimes referred to asmicrowave motion detectors) The sensor is able to detect when there are subtle

changes in these frequencies, since this would

signal a disruption. Generally more expensive than PIR because theyare highly sensitive, and are very reliable overlonger distances than other sensors.


12/21

CW Applications Typical applications include intruder alarms and

automatic door openers and toilet flushers


13/21

Ultrasonic Motion Detector use sound energy in order to detect movement in a

specific region.

This ultrasonic sound energy is emitted in waves,

which come from quartz-crystal transducers. When the sensor detects movement, the sound

waves are disrupted, which triggers the sensor.

commonly used in security alarms automatic doors,

since they are reliable and easy to install. The main limitation of an ultrasonic motion detector

is that it can be blocked by any material, and canbe easily disrupted.


14/21


15/21

Digital Motion Detectors Digital detectors are very accurate. The

technology is typically used in industries such

as railroads. used to monitor oscillator signals on a

continuous basis, and issue warnings to railwaycrossings when a train is approaching.

The oscillator frequency is normally heldconstant, and when changes in frequency aredetected, a signal indicating the change is sent.


16/21

Vibration Motion Detector Most vibration motion sensors use the

piezoelectric effect (the ability of some

materials to generate an electric field) in orderto detect motion.

Used in cameras for reducing vibration

A motion detector that detects simple vibration

can either be made from materials at home, orpurchased as an electrical device.


17/21

Determine what kind of sensor youneed Ultrasonic sensors can detect small motions but are

often triggered falsely. They are best used when a

large area needs to be covered. Passive infrared sensors are quite resistant to suchfalse triggering, but are best used within a 15-footrange, since the "dead" spots in their sensorypatterns become larger with distance. They are

best used in smaller spaces. Audible sensors are best applied in an industrial

facility or warehouse, where machinery noise,rather than people, breaks the silence.


18/21

PIR Motion Testing

When we design lighting circuit, we would like tolight up the LEDs only when there is somebodyaround.

The PIR sensor is a motion sensor based on passiveinfrared sensor which senses infrared emitted byhuman body.

Using PIR Module "KC7783R" which includes thePIR sensor and also the KC7783 motion detectionIC.

The PIR module is very easy to use, it contains only 3pins (1-Signal, 2-Vcc, 3-Gnd), where it detectssomebody moving, the signal line goes high for aperiod of time (3 secs for example).


19/21

PIR Motion Testing


20/21

PIR Motion Testing

Another demo of using PIR module,combining the use of AVRtiny13 as atimer.

When it detects motion, it will light up thelight bulb for 10 seconds, afterward it will

go into deep sleep to save power and waitfor the next interrupt send by PIRmodule.


21/21

PIR Motion Sensor

Documents

Motion Detectors