Motion Sensors

sensors are used to sense chochalates,biscuits ,products in retailshop and books

in colleges libraries

Google "robots motion sensors" to find IR and ultrasonic types. Also Google "home security sensors".

michaelwied; motions sensors are used every where, to turn flood lights, open doors, for security, they even have one that look s at a scene, if it changes it will let you know perry

Hi, I suppose that when you say " no beam to be cut" you mean that there is a transmitter in one end and a receiver in the other end wherein a trigger is made when the beam is cut by obstructing the path to the receiver. If that is the case, I would like to share to you that there is a commercial motion sensor, it is actually available in almost any hardware store, and what it does is just monitor something moving in its angle of detection usually about 135 degrees. The method of sensing is like that of sonar or radars, the reflected waves from the moving object causes the trigger to make alarm or what ever device you entend to activate. The distance that it could sense is quit limited though, only about 8to 15 ft. But I think there are models or types that detects motion much farther than the commonly available in the local market.

OK try www.glolab.com. They have a bunch of different types of PIR sensors. They have to be "designed" for different distances. They can however be focused. The normal angle is around 135°. By placing a different length of tubing over the sensor it can be "tuned" to a certain range.

We use alot of motion detectors from BEA. Their website is www.beasensors.com.

Have a great day!

Michael,

I found the Motorola design reference manual on Passive Infrared Unit it's a PDF file.

Motorola Design Manual

I hopes this helps you.

As several people have already said there PIR, ultrasound, radar, and laser ranging, also there vision systems.

The PIR detects motion through a sensor window like you walking in front of a window and someone sees you go by the person is the sensor.

The ultrasound units, radar and laser ranging all emit a signal to be reflected back to the unit. These units all have there advantages and disadvantages based on there means.

And visions units can be visible light, IR, and other means. They usual use some method of computers but not always. It could look for a change from light to dark,

the visual field could be broken up in to grids and the computer monitor the sections or even the pixels for changes.

This is just a general break down in some of the methods used.

I hopes this will lead you in the direction to the info you want.

Also you can Google your search with "diagram", "schematics", in it to help find drawings to circuits examples.

Good luck

Charles

I designed a PIR unit last year for automatic urinal flusher using a murata sensor. They are called pyroelectric sensors. (www.murata.com/catalog/s21e5.pdf)

PIR sensors often have a pair of diodes next to each other (in the same package) and a small slotted window in front of them will allow them to detect motion going across the face of the sensor. Actually they only respond with a slight signal change as incident IR on the face of them changes.

All of the detection is done by the electronics, traditionally a gain section feeding a window detector, its cheaper and easier to have the gain section feeding the A/D section of a small microcontroller that can then control the sensitivity and triggering times in software though.

Any hot objects in the scene will blanket out the IR from a human. They are not suitable in many appications, this could easily include the walls in a shed. Sunlight performance could be very bad if the walls heat up.

To detect in multiple directions and at a wider angle they need a fresnel lens or any sort of lensing system that will break the scene into small windows. Anything with enough IR moving between the windows will cause a signal as the IR on the lens increases and decreases. The lens selection and positioning is more important than the sensor itself.

Range can be adjusted by the amp gain or by software if using an opamp. The ones I made where good to about 15 metres indoors, I would suspect in a hot walled shed they would be lucky to work at much more than a metre, if at all.