Robotic vision

[RoboWanabe]

Hello Engineers of the world i need help with a project. ideas would be appreciated.

Ive been asked to build a robot sensing application which can detect diffrent coulors, mainly rgb? i have never done anything like this so have not got a clue where to go. if any one has got any ideas or pointers for where i should start i would realy appreciate it

Thank you

 

[Sceadwian]

Use an RGB camera.... Feed the output of the camera into something you can process.

 

[dougy83]

Ive been asked to build a robot sensing application which can detect diffrent coulors, mainly rgb?

You could also use photo sensors (e.g. CdS cells, phototransistors, photodiodes) with a coloured filter (red/green/blue) on each. The CdS cell will change resistance (while the phototransistor/photodiode will change the current they pass) depending on coloured filtered light level.

 

[Vizier87]

you're talking about image processing. That's difficult stuff, but if you're willing, you can explore DSPs like TI's Da Vinci Processors. And like Scead said, an RGB camera.. or I've seen people using CMOS image sensors.

 

[dougy83]

didn't he just ask for a colour detector?

 

[carbonzit]

I'm with you, Dougy; simple sensors would be much simpler to implement and, I suspect, are what the O.P. is really after in their project.

But we'll have to wait til they get back to us with a few more details.

 

[Vizier87]

Whoops. My bad. I saw the word "camera" and this blew up into the enigmatic Image Processing topic.

Yeah, RGB sensors should be fine for this purpose.

 

[RoboWanabe]

wow this is more than i can ask for, ive got a good few leeds to follow thanks people. i think the phototransistors idea because ive had exprence using them, i need to do more research into the coulor filters tho, would this just mean i can detect, redgreen and blue? or am missing something here like, you can use all three to make any coulor? lol sorry electronics im getting good at, but this image processing stuff i have never done. ive used matlab and found the rgb levels from individual pixels, but i wouldunt no how to implement matlab with the the camera?

Thanks for your intrest.

 

[magnatro]

https://www.electro-tech-online.com/custompdfs/2011/10/Soft_May09.pdf read this article... this will be a great help for you.. its from an indian magazine Electronics for you. The thing is tried and tested. (me in person tried it and got it running), its a good piece of software, the hardware can be done using simple L293 divers and geared motors.

 

[dougy83]

would this just mean i can detect, redgreen and blue? or am missing something here like, you can use all three to make any coulor?

With R,G & B inputs you can detect any colour.

ive used matlab and found the rgb levels from individual pixels, but i wouldunt no how to implement matlab with the the camera?

Did you want to use matlab to process a camera frame? It can be done; there's an image capture component or you can write an interface using the matlab c compiler.

 

[ronsimpson]

Color filters will work but there is too much to go wrong. Calibration is a real problem.
For a prototype I used the product in the link below. Then for production I used the TCS3200 sensor that is inside. It has the filters inside, calibrated, and ready to go. The output is a frequency, not a voltage. It is easy to measure with a PIC or other small micro. I built color meters for two different companies using this. One is used to calibrate medical equipment.

**broken link removed**

 

[RoboWanabe]

thanks ron but i think what your sugesting might be classed as cheating lol but i will see if i can. if not ive loocked at the cds cells and they dnt seem good enough, seems they should only be used for simple application. and i know about photo transistors but how do i use them with a color filter?

 

[4pyros]

Lego Mindstorms has a simple color sensor, you could look at that.

 

[RoboWanabe]

cheers but im looking to acutal make one of them my self, and that would defeat the object.

 

[ronsimpson]

"Home work"
I don't know 100% but I believe the Lago is the same as the Parallax.
You could get the 3 color filters and 3 photo transistors and use three analog inputs of a stamp or PIC microprocessor.
The cost of the 3 filters will be the cost of the TCS3200 sensor. $3.00 to $5.00 each
You will need a way so the sensors can only see the object under test and not background.
You will need to calibrate. Looking a white pater the three outputs should read the same and in a black room they should read the same.

 

[4pyros]

[QUOTEcheers but im looking to acutal make one of them my self, and that would defeat the object.][/QUOTE]
Yes look at lego sensors and see how thay work. People were making them before Lego made them and there is all kinds of info on them if you look in the right places. Thay use three colored LEDs. So once again "look at them".

 

[RoboWanabe]

My project leader is so poo. he keeps makeing me feel like im not on the right track and is very vague when talking to me.
He told me the project was on robotic sensing and i needed to research wasy to detect colour so i go of and research all the diffrent ways robtic vision and post some posts on here and still he makes me feel like all my ideas are not good enough.
I told him 1) i could use colour filters and photo transistors
2) i could use a purpose built colour sensing ic to do the job ( this might of been cheating tho lol)
3) i could use a webcam and matlab.
4) i could use a camera with a pic.

does anyone know any other ways. prefably with an end game of just using a camera a microcontroller( a PIC micro).

Thank you for your help again. i just realy want to make a wkd project but im the sort of person who constantly needs reasuring im on the right track but my Project leader dosent understand this! Please some one tell me im on the right track lol