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Topic: Sensors for detecting direction of motion (Read 6157 times) previous topic - next topic

Chris_Gong

I'm planning on making some kind of system for my room to send different messages to my Arduino UNO to activate specific LEDs depending on whether someone is either entering or exiting my room. My question is which sensors would be most appropriate for differentiating between an entering and exiting motion. I first thought about a PIR motion sensor for this but I'm not sure if it's able to distinguish between different types of motion. Perhaps multiple PIR motion sensors would suffice? Would multiple laser sensors be a better choice? Or does this project require other hardware?

SMM2

I had a very similiar post to this that talked about this topic, so it may be of help to you.
This post
"Success is not built on success. It's built on failure. It's built on frustration. Sometimes its built on catastrophe."

Chris_Gong

SMM2, that is indeed very similar. I wonder though how did you ever get your robot to handle double-counting? For instance, how did you prevent it from being activated by a dog or a ball going in and out of your room?

arduino_x, is there any advantage to using the ultrasonic sensor vs two laser sensors other than quantity? For example, I would think that you would be able to get a more accurate read of a person's speed with ultrasonic, is this true?

CrossRoads

I would think light would be more precise than sound as it travels faster and is less bothered by air temperature, humidity, barometric pressure, etc.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

PaulS

I would think light would be more precise than sound as it travels faster and is less bothered by air temperature, humidity, barometric pressure, etc.

On the other hand, it is more affected by ambient lighting, dust, etc.

Chris_Gong

Would it be naive to measure speed by taking the time it takes to get from one beam to another when knowing the distance between the two beams?

Also, I've been thinking about implementing a similar system for my U-shaped driveway to tell me which side is full. However, if I use an ultrasonic or beam, is there any way to avoid counting objects that aren't cars? This is kind of related to my previous inquiry about preventing the sensors from detecting my dog entering my room.

PaulS

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Would it be naive to measure speed by taking the time it takes to get from one beam to another when knowing the distance between the two beams?
No. But how is speed important?

Does it matter if someone enters the room quickly? Does it matter if someone enters the room slowly?

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Also, I've been thinking about implementing a similar system for my U-shaped driveway to tell me which side is full. However, if I use an ultrasonic or beam, is there any way to avoid counting objects that aren't cars? This is kind of related to my previous inquiry about preventing the sensors from detecting my dog entering my room.
A car will spend some amount of time with both beams broken. A dog will spend a lot less time, unless it stands still. A high enough powered laser would minimize that possibility. 8)


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