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Topic: Measuring Height, Width & Length of a Box? (Read 1 time) previous topic - next topic

NI$HANT

What sensors are recommended here? or what strategy should i follow?

measurement from all sides?
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GoForSmoke

What size box and how close do you need to be right? Is a tape measure just too 20th century?


I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

NI$HANT

Quote
Is a tape measure just too 20th century?


haha, indeed an acceptable humour.

Size is something like any box that can be kept on desk actually not sure and the proximity to the box isn't a problem at all because i first want to make it work moreover its not a concern to me.
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GoForSmoke

You might find some interest in the Makerbot 3D scanner, which is Open Source.

I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

Nick Gammon


What sensors are recommended here? or what strategy should i follow?


I'm tempted to reply here, but have already been told off once for not being helpful, so I'll let it pass.
http://www.gammon.com.au/electronics

GoForSmoke

I imagine that with 1 laser, 1 light sensor in a tube, and a very precise servo you could get distances somewhat accurately just bringing the laser dot into view of the tube. I wonder if that's part of how the 3D scanner works?

I also have a feeling that I missed a really good zinger. Would a true Evil Genius deprive us so? Oh yes, passive sadism... right?

I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

NI$HANT

3D scanner , now i think here the maker bot ones would be preferable at the most extent as its already an expensive thing and then as such hacking a 3D scans as ones from HP would depict being too costly.
"Real Men can Accomplish  Anything"
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ਫ਼ਤੇਹ ਕਰੁਂ!

GoForSmoke

The 3D scanner I saw was supposed to cost about $50 to build. Not the best but it works.
Open Source, you have every detail of how it is made and works. How does it know where in 3D to place a dot? That is the part you care about first. Maybe more but first, how does it measure?

I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

NI$HANT

Quote
How does it know where in 3D to place a dot? That is the part you care about first. Maybe more but first, how does it measure?


True, this is something im coming back with to this thread! IF i'm able to deduce everything.
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GoForSmoke

If a light sensor is limited to only seeing along a line (in reasonable distance) and the line intersects an object then detectable (say IR for IR sensor) light falling on that object at that point will be sensed.

With a turning mirror you can cause a laser beam to sweep so that it crosses the view line of the sensor from close to far.

Knowing how fast the mirror turns and adding one more sensor to know when the sweep starts it should be possible to know the angle the mirror/reflected beam is at when the first sensor sees the beam reflect from the object just by knowing how long it took from 'start'.

I'd bet there's already a patent or copy-left that uses that.

I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

NI$HANT

#10
Jul 12, 2012, 04:56 pm Last Edit: Jul 12, 2012, 05:06 pm by NI$HANT Reason: 1
@GoForSmoke , I was thinking for an Alternative although what you describe is sheer physics and i got interest in it but then for some rough measurement i can use a PINGING sensor like a HC-SR04 or one from the MAX sonar series.

THE IDEA!
THis idea involves moving on x and y axis a single distance sensor and then move it along a predefined area for example i can make the whole system to measure a maximum of 15inch BOX in width and height so the system will measure box any box size under this defined value.

The assumption is that the BOX's surface would be plain and smooth as most boxes have and as such at the point the sensor gets on receiving the same input of distance (ignoring the predefined values for the distance to ignore), I think its hard to put this idea in words im as such attaching the diagram of my idea.

update: There would be a marker on the base in which one has to place the BOX for measurement so the boundaries of that marker would be the extent to which the sensor will move on the x and y Axis, The only problem is dealing with the beam WIDTH ,this will destroy the plan altogether.
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pylon

Have you read the data sheet of your ultrasonic sensor? The opening angle is too high to get a useful result when moving around. Try it manually with such a sensor, you'll see immediately that this way it won't work.

I'd go for the cheap MakerBot 3D scanner too. This is probably cheaper than the ultrasonic solution and much more accurate.

Grumpy_Mike


GoForSmoke

Actually I think the trick would be to aim the laser and sense through/off a spinning prism/mirror.
It's a reversal of POV display that can put a pixel on a wall, I'd be detecting the pixel *then* in the sweep instead of emitting one. Lol, it could probably use some of the same code!


I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

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