dust detection

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Thread Starter

ina

Hi..

Just want to know if there is any sensor that can be used to detect dust (either on the floor or carpet). Actually I'm working at designing a vacuum cleaner robot. Basically it will works when it detects dust on the floor. And I'm using a Motorola 68HC12. Perhaps, anyone out there can help me here.

Regards,
INA

 
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Lee Thornton

I dont think you will be able to detect dust on the floor or in the carpet, but you probably could detect it in the airstream after you turned the vacuum cleaner on. Photo cells perhaps, or some type of electrostatic detector?
Just a thought.
Lee
 
D
While I think your attempt to only vacuum on demand is interesting, I think you would be safe to assume that there was _always_ dust on the floor. Certainly by the time the robot finished vacuuming the entire room there would be dust at the starting point. You may want to trigger the vacuum cycle based on time instead. Otherwise the robot may just operate continuously!

Cheers,
Dean
 
hello INA,
Not a sensor expert but could capacitive changes reflect the presence of
dust thereby permitting the use of capacitive contactless sensors.
Anand
 
J

Johan Bengtsson

I seriously doubt you get something reliable out of that. The difference between dust and no dust would be so small that the errors will be greater than the actual change.

sorry

/Johan Bengtsson

----------------------------------------
P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
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C

Clark Southoff

Hi INA:
The simplest method is light reflection. By using a emitter and detector pair, the amount of light reflected will show up as almost noise on the (photodiode or photo-transistor) detector.
An intriguing detector is the Texas instruments TSL 230 light to frequency converter. It has a 160 dB range on detection, 1 Hz to 1 MHz output.

Best regards
Clark Southoff
Technology Wranglers Inc.
 
C

Curt Wuollet

Hmmmm...

I would use a light source and and detector in the same fashion as a reflective proc sensor that is they both face the same direction. These would be mounted at a low angle to the floor so that a clean floor doesn't reflect back into the sensor. Objects (dust) on that specular surface would reflect back and be detected. It's the same principle that you would use to see the dust. Looking straight down, it's hard to see. If you get down low and look across the floor, you see every little furball.

Regards

cww
 
S
We used to measure the thickness of thin films by the vibrational frequency of quartz. As the metal film was deposited on the quartz, atom layer by layer, the mass changed and thus the
frequency. While dust would not be nearly as dense, it might be worth a try. I think you can buy these meters from physics catalogs. You would also probably need to coat the top of the quartz with a sticky substance.

Another idea, might be to capture some dust on a wet metal surface, and then heat it. the amount of smoke may be an indication of how much dust is present.

good luck

Larry
 
J

Johan Bengtsson

<clip>
>Another idea, might be to capture some dust on a wet metal
>surface, and then heat it. the amount of smoke may be an
>indication of how much dust is present.

That way you might not need to turn on the
vacuum cleaner at all.... <grin>


/Johan Bengtsson

----------------------------------------
P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
----------------------------------------
 
M

Michael Griffin

A couple of people have suggested using the reflection of light to solve this. I would be interested in just what they believe the light is
going to be reflecting off of. The sensor has to work with "floor or carpet". "Floor" could mean various types of tile, wood, concrete, etc. Of
course rugs may have to be taken into account (although a robot vacuum cleaner may have to avoid these anyway). Tile has many textures, and there are many types of carpet.
In addition, many sensors may be needed to cover a large area, with the additional complications of furniture and other objects. Sensors mounted very close to a tile floor will get covered in dirt from mops. Dust will be very unevenly distributed. The reflective properties of tile will change dramatically when the floor is waxed or polished. If you use a lot of sensors, they have to be installed and networked somehow and the various data has to be integrated by some sort of master controller.

If there is enough dirt to be reliably detected by any area sensor I can imagine, then the floor should have been cleaned long ago. I don't wait until there is a noticable amount of dirt on my floor before I vacuum it. I think that working on a timed or scheduled basis is the only method that will work satisfactorily. I would not want to require someone to have a high degree of skill to operate or maintain a vacuum cleaner.

If you are looking for fancy features to add (and I think a robot vacuum is challenging by itself), then come up with a way of measuring how
much dirt you actually did vacuum from each "zone" (e.g. room) after each operation (in say, grams per square meter). This historical data could be used by the operator to decide how often to vacuum each area. For example, zone 'A' may get need to be vacuumed twice as frequently as zone 'B' because the dirt per square meter is accumulating faster there.


**********************
Michael Griffin
London, Ont. Canada
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Michael Griffin:
> If you are looking for fancy features to add (and I think a robot vacuum
> is challenging by itself), then come up with a way of measuring how much
> dirt you actually did vacuum from each "zone" (e.g. room) after each
> operation (in say, grams per square meter). This historical data could be
> used by the operator to decide how often to vacuum each area.

Actually, once you have this data, the robot itself can use it to decide how often to vacuum each area, using any number of learning/prediction
models, from the simplest to very sophisticated.

Something like "vacuum whenever the estimated pickup will be X g/m^2, but at most every Y days".

Of course, this doesn't take into account different pickup percentages from carpet and tile, but there's not much you can do about those. Maybe have different settings for them (if you can tell them apart).

Jiri
--
Jiri Baum <[email protected]>
http://www.csse.monash.edu.au/~jiribvisit the MAT LinuxPLC project at http://mat.sourceforge.net
 
C
One way to solve the coverage problem would be to use a cheap board camera. Once you've grabbed a frame you can easily mask to just the area of interest and remove orthogonal obstacles. Actually, you might want to avoid those obstacles so mapping them might be the way to go. A gamma threshold would pick out dirty carpet and dust on bare floors. It would be sophisticated but the accuracy need makes it possible as nothing bad happens if you vacuum a little extra. I would suggest a small diddle or oscillation in the mount and subtraction. The floor would drop out and the dust wouldn't. Intriguing problem though.
You can do a lot with camera data, there's an enormous amount of information there. Might be too much for a 68HC12 in realtime.

Regards

cww
 
D
Why try to detect dust over the entire floor? Perhaps one sensor, with sensor head pointing towards the ceiling, high enough that it doesn't get mopped, and measure the dust deposited on that sensor. Assume that the floor is getting the same amount of dust. The only problem becomes cleaning the sensor when the room is vacuumed.

Davis Gentry
Delta Tau Data Systems
 
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William Gornto

Actually, install a learn mode and you decide the first 100 rimes when to run..Record each run result and use that data..after suitable filtering..to schedule future run events
 
D
This is actually a good idea. You could mount some type of target or reflector, set a simple photocell to low gain and trigger the vacuum on
loss of target. There is one major drawback however. You could have dust bunnies all over your hardwood floor but not enough surface dust on the sensor to start the vacuum!

Dean Reimer
Westroc, Inc.
 
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