A more Precise directional sensor

sigpaw@hotmail.com's picture
Submitted by sigpaw@hotmail.com on Tue, 03/15/2016 - 01:12

Forums:

I'm curious about this prospect, I wonder if anyone else here has tried anythnig similar?

I'm looking at this small parabolic reflector: http://www.amazon.com/Solar-Spark-Lighter-Survival-Tool/dp/B002MUG0E6/re...

Place an infra-red sensor at the focal point and an ultrasonic sensor in the same vertical plane. Put the assy on a stepper motor and scan for infra-red hot zones (animals). Then use ultraborg to measure range.

Comments? Observations?

(FYI - I'm hoping to make a BOT that can find and follow our "house rabbit" around our home).

lars_the_bear

Tue, 03/15/2016 - 11:09

Hi

Whatever did the poor rabbit ever do to you? :)

I have no idea what kind of IR sensor would be needed to detect the heat generated by a bunny -- but I've no doubt there are such things -- passive IR burglar alarms are frequently set off by pets. I imagine that a parabolic reflector could focus IR the same as visible light, but my suspicion is that placement of the sensor at the exact focal point would be critical.

I'm sceptical about the ability of an ultrasonic transducer to measure distances accurately at ranges more than about 1 metre. I rather suspect that a bunny would not reflect very much anyway, making the problem worse. But do you really need ranging to track something? All you need (I would think) is to keep the target centred.

I don't think your proposal would be easy to implement because, apart from anything else, if you're tracking a moving object around, you've also got to deal with collision avoidance. But it could be interesting.

Best wishes
Kevin

sigpaw@hotmail.com's picture

sigpaw@hotmail.com

Tue, 03/15/2016 - 14:55

Hi Kevin!

:-) Well actually we have five bunnies, but they "take turns" being free in the house. Otherwise we would soon end up with THOUSANDS of bunnies. LOL

But to answer your question; they've done nothing, other than leave a few small "coco-puffs" here and there on the floor. The reason I want the ranging is to be able to keep back a "respectable distance" (a meter/yard should suffice).

I have an old Roomba that I can scavenge for the vacuum module. My diddy is to be assigned coco-puff clean-up duty.

A gentlemen named Steve Ciarcia came up with the scanner idea many, many years ago (1980s Byte magazine). That article made quite an impression on my young mind (I was 20-something at the time). He used a Radio Shack solar cigarette lighter and a Polaroid ultrasonic sensor kit. He was accurately ranging out to 4.5 to 6 meters. https://books.google.com/books?id=zAsN0XCHbFsC&pg=PA42&lpg=PA42&dq=i%27v...

I ordered the complete Ultraborg kit, so I will have three other sensors for obstacle avoidance. But with my wheel count sensors added (as well as my mag compass sensor), I shouldn't need to use them as much since the furniture doesn't move often here. Thus diddy would only need to map the environment once. From there on an occasional "ultra-wag" should keep him homed in. The infra-red scanner will help diddy keep track of the bunns, as well as any people (wife and I) that should appear in his view.

I've owned/used a rather clever Israeli robot since 2002. It mows my lawn autonomously. It uses a compass and wheel count sensors, as well as an RF energized perimeter wire - similar to the setup "Invisible fence" uses for dogs. It does an excellent job of navigating around, also a decent job of obstacle avoidance. I have watched and studied it for 15 years, also had it apart for various upgrades a few times. Roomba and RL-500 use bump sensors to detect objects, I'm hoping to replace that with ultrasonic ranging...

One curious fact. When ever a neighborhood animal (dog or cat) encounters RL-500 (during a mowing session). They generally ignore it (other than an initial curious sniff). It's like they know it isn't alive...

Cheers,
'sig

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