Motion Detectors for Triggering Inputs

In summary, the conversation discussed using motion detectors to trigger inputs, specifically in the scenario of a car approaching a gate and triggering the opening mechanism. It was suggested to look into other options such as RFID or ultrasonic motion sensors, and to consult forums for further advice on how to achieve this application.
  • #1
Khamis
2
0
hi all

im new in this forum and i have a quick question:
i need to know which motion detectors can i use to trigger inputs
i.e , if a motion detector detects another motion detector , then it will trigger the input, otherwise, nothing will happen if the motion detector dosent detect the another motion detector.

thx a lot :)
 
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  • #2
Khamis said:
hi all

im new in this forum and i have a quick question:
i need to know which motion detectors can i use to trigger inputs
i.e , if a motion detector detects another motion detector , then it will trigger the input, otherwise, nothing will happen if the motion detector dosent detect the another motion detector.

thx a lot :)

Welcome to the PF. There are many types of motion detectors, and your requirement sounds a bit unique. Can you tell us what the application is so that we can understand your requirements better?

The simple motion detectors use a multi-segment IR lens and an IR detector behind the lens. They are called PIR (passive IR) motion detectors. As a source of IR (like a human body) moves in front of the PIR device, the multiple images of the moving IR emitting object are projected back towards the IR sensor. Because there are multiple "blobs" of the image formed by the multi-facet lens, the motion causes the output of the IR sensor to vary. This variation is detected, and trips the motion sensor.

So are you trying to detect motion of humans and animals, or motion of robots, each with a motion sensor on it?
 
Last edited:
  • #3
This does sound a bit peculiar. If it's just a matter of one detector being triggered by another one, then I assume that you have control of the design of both. Wouldn't it be easier to just directly couple the two with an optical or radio link?
 
  • #4
Motion detectors are just passive devices and they can't trigger each other unless you connect them electrically somehow.
 
  • #5
thx all for the reply

what I am trying to do exactly is: I need to install a motion sensor in my car, and the other motion sensor will be placed in the gate opener circuit in a place that will keep the circuit open, so when the car reaches home or near the gate, the motion sensor that placed on the circuit will close it in order to complete the circuit to open the gate without pressing a button from the remote control :)

thanks a bunch
 
  • #6
It sounds more like you need an RFID stystem.

These are used in some big cities (like San Francisco) to automatically collect revenue from vehicles going over a bridge or a toll road.

Cats and dogs have a RFID chip placed under their skin so they can be identified

You don't want every person out walking their dog to open your gate do you? You want only your car to trigger it. Motion detectors are pretty crude devices and they can't discriminate between targets. They just receive infra red from anywhere and trigger if it changes suddenly.

I don't know if you can buy these RFID devices as a pair. I tried to get some for a running club to automatically log the times of marathon runners, but it got too expensive.
Try Google for RFID?
 
  • #7
For RFID, check out this:
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/rfid/List/0/SortField/4/ProductID/517/Default.aspx

You might also post your question on one of their forums, like for the Basic Stamp, the guys there are used to doing stuff like this. Also, there are ultrasonic motion sensors and you could use IR code flashers to ID something like a car. Passive infrared isn't the only option.

good luck,
Mark
 

1. What is a motion detector for triggering inputs?

A motion detector for triggering inputs is a device that detects movements within a specific area and sends a signal to trigger an input or action. It uses various technologies such as infrared, ultrasonic, or microwave to detect motion and can be used in a variety of applications such as security systems, automatic doors, and lighting control.

2. How does a motion detector work?

A motion detector works by emitting a signal, such as infrared light or ultrasonic waves, and then measuring the reflection of that signal. When an object moves within the detector's range, it will cause a change in the signal, which triggers the detector to send a signal to the input it is connected to.

3. What are the different types of motion detection technologies?

There are three main types of motion detection technologies: infrared, ultrasonic, and microwave. Infrared detectors use heat signatures to detect motion, ultrasonic detectors use sound waves, and microwave detectors use radio waves. Each technology has its own advantages and disadvantages, and the best option will depend on the specific application.

4. What factors should be considered when choosing a motion detector for triggering inputs?

When choosing a motion detector for triggering inputs, it is important to consider the technology used, the range and sensitivity of the detector, the power source, and the environment in which it will be used. It is also important to consider the specific needs and requirements of the intended application.

5. Are there any limitations to using motion detectors for triggering inputs?

Yes, there are some limitations to using motion detectors for triggering inputs. Environmental factors such as temperature, humidity, and interference from other devices can affect their accuracy. Additionally, some types of motion detectors may not work well in certain environments or with certain types of movement. It is important to carefully consider these limitations when choosing a motion detector for a specific application.

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