Colour detection camera?

[UroBoros]

colour detection devices

Hai
I want to sort black colour bad rice pieces from a flowing stream of rice in a Rice mill.
(Colour sortex mechine)
What type of camera can be used to detect such colour changed items in a bunch of similer particles.

And how to interface such a camera to a microcontroller?

And I doubt that insted off camera these devices are using some type of colour sensors for detection.

I have seen a device which employes PIC16F73A which controlles this camera and sortes the black coloured rice by blowing it of by a compressor and valves controlled by same pic.

Please throw some light into the this theary and practical approach

Picstudent

 

[IanP]

cameras with colour detection

I don't think a PIC microcontroller can do this ..
To analize colours you will need more than a small microcontroller ..
This will be a good opportunity to get it touch with LabView and its machine vision capabilities: https://www.ni.com/vision/
Regards,
IanP

 

[UroBoros]

colour detection

hai

Thanks for the post.

I think I will make some amendments to my earlier post!


I feel it is not a camera,But it is some type of sensor. The camera like device has some 3 connections only to the 16F73 chip board.


Actually the device is not capable of sorting all colours.

What it is doing is only blowing off the dark coloured rice pieces in a flowing stream of yellow or somewhat white coloured good grains.

seems some kind of sensor capable of detecting the presence of a dark colour in front and gives a logic output.

But the complexity is that only two cameras (sensors) watching small seven rice flowing grews in front of it and controlles 7 air valves to blow off black pieces in each grew.

thanks
Picstudent

 

[IanP]

Have a look at these sensors:
**broken link removed**
They are linear arrays of photocels (>2000)
Maybe they will need some external optics to focus on certain area.
But I think they may be suitable for your application ..
Regards,
IanP

 

[marie65]

I've made some time ago a colour sensor based on Mazet's (www.mazet.de) RGB diode array and AVR Mega8. It measure the color of a 2mm target. The sensor cost around 40 Euros.
Anyway, for your task, you can use a gray level sensor to build your own sensor, much cheaper and easier to interface then a RGB one, or you can buy an industrial one available at sensor producers, like Omron, Banner, Idec etc

 

[UroBoros]

Hai
Thanks for the links.

but the equipment which I have seen which is mentioned above seems to be using a camera.!


I have now changed my opinion because the service personal for that sortex mechine have connected their 'sensor 'in the this mechine to their alignment device which has a monitor and subsequently they showed the pictures of assisting helpers on that monitor. As the device was able to show the picture of the people on screen ,it should be a camera ;not a sensor .What is your opinion?


But how a PIC16F73 will controll this camera?

Only three or 4 wires from this camera running to the pic board.

Thanks
Picstudent

 

[IanP]

Most likely the wires will be: (+)V, composite video, 0V.

See the picture below: it is structure of single video line.
If you analize this picture you can see that if you take a sample at certain point you will be able to distinguish its colour, as the scale goes from black (at the bottom) to white (at the top) ..
If your A/D converter is fast enough, say, 1µs, you will have roughly 50 samples per single line that are directly proportional to colour of an object in front of the camera lens ..
You will need to scan the whole frame (I don't think you have to scan every single line; out of ≈500 lines 100 will be more than enough) to find a darker object .. so if you do it 25 times per second (as the strucuture of PAL video signal allows) you will have planty of data to play with ..

Regards,
IanP

 

[UroBoros]

Thanks a lot for the the info


I have once again closely examined the controll board.


Sorry the PIC is 16F873A, two numbers for each section.

One camera and seven blowing valves are connected to this board which uses two numbers of 16F873A's .It seems one PIC controlles the camera and other controlles the valves.

Your above mentioned ADC principle is employed i belive.They are running both the PICs with a 16Mhz crystal each.

What type camera is that? How can i search it?

it is a small black one almost the size of a stepper motor used in old floppy drives.

The board has 7 switching transistors to drive the valves and some 14 other 8 pin dip ICs for which the names they have scrached off!

thanks
Picstudent

 

[IanP]

Try some small cameras for security applications .. https://www.web-tronics.com/small-board-cameras.html ..

For analyzing of video signals you will need the following blocks:
Video buffer (example EL2044 - 8-pin DIP) or buffers ..
Sync separator (example LM1881 - 8-pin DIP) ..
Black level clamping (An electronic process, which establishes a fixed DC level for a picture signal at the beginning of each scanning line. The black level* of a video signal is set to a specific, predefined DC voltage) ..
White level peak detector ..
It looks like they did it by using these 8-pin DIP ICs ..

Regards,
IanP

 

[artem]

If you know the point were the rice is going to be detected - it is exactly the number of usec from start of vert synch signal from your camera - you should make sample and hold signal which grabs video output after defined time usec . As grabbed SH signall is permanent - you will be able to easy analyse its gray scale by your favorite PIC's ADC .