Advice on what sensors to use

Moderators: grovkillen, Stuntteam, TD-er

Post Reply
Message
Author
bobbybeans
Normal user
Posts: 119
Joined: 26 Feb 2017, 17:30

Advice on what sensors to use

#1 Post by bobbybeans » 13 Jun 2019, 16:04

Hello. I am need of advice on what sensors to use as I am running out of options and any advice would be great.
So project idea. I have a african pygmy hedgehog. He is the cutest and I love IOT devices so I would like to track him.
Currently I have xiaomi temp sensors to track inside his house and inside the cage. It turns on the heating mat when it's too cold and off when heating is reached.
He also has a wheel that I track rotations which then I am able to calculate distance he has ran based on the diameter of the wheel and other stuff like first seen last seen etc.
I have been building him a new cage (the one we currently have is massive and takes up way to much space. ) Since I want him to have the same amount of space, I build up! He will now have 3 levels bottom- sleeping house, middle -food, and top wheel. To get to each level he has a ramp he plods up and down.
Here comes my problem. I would like to track direction of which way he is going.
My initial thought is to have sensors at top and bottom of each ramp. If bottom one goes off then top goes off that means he went up. If top then bottom goes off that means he went down a level.
My current problem is which sensors to use. I am limited in options to what I can use here is a breakdown of all the sensors I have considered and why I can or cannot use them. Please any sensors I have missed or you think my assumption is wrong about the current ones please correct me or give me advice.

Vibration sensor- This could be possible. I would place them under the top and bottom of the ramp but I think it would create to many false positives with both of them vibrating at the same time.

PIR sensor- This could be used potentially. This absorbs IR and outputs a signal of detection. The current problem, it has to wide of a field of view. Would have to work on narrowing that down so it does not produce FP

laser sensor - , Cannot be used, this would be a laser beam powered and on the other end hooked up on the arduino with laser detector sensor. This not only could damage his eyes, he is nocturnal and if there is much light out /around he will not come out of his house. He will try to avoid the light as well.

ultrasonic distance sensor- cannot use this. Hedgehogs can hear the frequencies of these and he refuses to get out of his house to eat, drink or run on the wheel

distance/range detector- Something like this APDS-9960- this MAY be possible, Don't have one to try. I have read online items that say it is inaccurate for close distances (less than 50cm) current distance would only be about 10-15ish. Also this emits IR, while not much hedgehogs can see infrared and if it's too much he wont come out of his house.

radar sensor- This cannot be used as it goes through each floor. While it would be great in detecting movement it wouldn't be accurate :(


Capacitive touch sensor - MPR121 - This could possibly work- The ramp is covered in fleece which I am hoping it would be able to detect through that, Fleece is about 2 -3mm thick and would a hedgehog be enough to trigger it? Will order one to find out.

UV sensor - useless , hedgehogs dont emit UV only heat which is IR

Temperature sensor. - This could work similar to the ones found in the IR laser temp meters. However are there cheap ones out there and are they small? They would have to be always operating and very fast in responsiveness to detect a change in heat for maybe .5 second as he is passing? Any links out there to something like this?

Weight/button sensor - I dont think this would be very effective as I would have to guarantee he has to step on both of the sensors 100% of the time

Strain gauge- not sure how this could work. this would be on the bottom of the ramp to detect bending. I dont think it would be accurate enough at the top and bottom. if I put it in the middle it would be good as the ramp flexes a little but then i couldn't tell direction with only 1 sensor.

microphone sensor. - I dont think this could work reliably as it would be similar to the vibration sensors. based on the noise of him walking from top to bottom it would create lots of false positives.

TEMT6000 - This may work depending on how sensitive it is, at night it would be very dark in his cage. Would it be able to detect a change from 1 to 2 lux without having lots of FP. It would be on the side of the ramp , top and bottom as he passes it could potentially trip it by blocking the little light there is. Suggestions?

User avatar
ThomasB
Normal user
Posts: 333
Joined: 17 Jun 2018, 20:41
Location: USA

Re: Advice on what sensors to use

#2 Post by ThomasB » 14 Jun 2019, 01:12

Why not use simple optical detection? An IR LED on one side, with a matching photo transistor on the other side. When the hedgehog walks on the ramp it crosses the sensed path and breaks the beam, which can trigger GPIO events on ESPEasy. One set near the top of the ramp and another at the bottom will provide the GPIO input states for rules that determine pet location and travel direction.

For example, basic optical sensors like this: https://www.adafruit.com/product/2167

- Thomas

bobbybeans
Normal user
Posts: 119
Joined: 26 Feb 2017, 17:30

Re: Advice on what sensors to use

#3 Post by bobbybeans » 14 Jun 2019, 13:31

hmm, this could work. Normally he doesn't like IR light as I had a night vision camera with IR leds which bothered him. Those were very bright though. I will order that along with a load of other sensors and see what works. Still open to other suggestions as well :)

By the looks of the video it wouldnt be very bright (which is good) and it only has a 10 degree angle. I need to find something like that on aliexpress since they don't see that anymore. Closest thing I can find is a proximity sensor with IR, GP2Y0A21

I will definitely be using ESPeasy. espruna IMO is not powerful enough for custom stuff (great for box standard sensors) and havent tried tasmota.

User avatar
ThomasB
Normal user
Posts: 333
Joined: 17 Jun 2018, 20:41
Location: USA

Re: Advice on what sensors to use

#4 Post by ThomasB » 14 Jun 2019, 18:43

I need to find something like that on aliexpress since they don't see that anymore.
Ebay has several sources at low cost. https://ebay.to/2ZvVhcF

But if you must order from AliExpress then perhaps these might work out: https://bit.ly/2wS6Kqy

- Thomas

Post Reply

Who is online

Users browsing this forum: Google [Bot] and 0 guests