Ways to detect colour?

For my robot I want to implement colour sorting, but I don’t have any more vision sensors, the other team is using it. Are there any other ways to detect colour for indexing?

Our school won’t let us buy more equipment like the sensors coming up soon.

Vision sensors are the primary way, I can’t really think of anything else…

Does anyone have any ideas?

It would also be possible using the line tracker/light sensor (if you have one) and some coloured plastic as a filter (legal under R8 a.)
The line tracker might give enough of a variation between red and blue without any filter, used to work for the red and blue foam tiles.
Would need to be close proximity (~10mm) to the ball.

The new Optical Sensor is probably the best bet for this if it was possible for you to get one.


The line tracker is an infrared sensor, and sometimes plastic dyes look the same in infrared. It didn’t change much at all between the red and blue goal last year.


Yeah, they certainly could be equally as reflective.

line trackers are terrible for detecting different color in my experience. So is the vision sensor actually, if you don’t have it placed under ideal conditions. I’ve heard of people using the light sensor with color filters, but I don’t know the specifics of how to do that. I think it involves putting a piece of slightly transparent material, tinted heavily to the color you want to detect, so it only lets that color of light in. (could be wrong, just guessing here)

Ideally, you would get the new color sensor when it comes out. you could probably make the pitch that it’s relatively cheap (I’d imagine it will be something like 20$) and it can be used for pretty much every game. But I understand you might not be able to do any of these, in which case you just can’t do color detection.


well I hope its better at seeing color than my team’s driver… who is colorblind.

He could tell the difference between all the colors last year. But not so easy now.


Line trackers are just reflective IR light sensors. They can’t accurately distinguish colour but you might get very different readings depending on the difference of reflected light.
The vision sensor is excellent at this if set up correctly. The new sensor will certainly be the best solution, the proximity sensor in it should be useful for letting you know when a ball is present and then you can check the hue values.

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When do you think the optical sensor will be available to purchase and when will it arrive to New Zealand, VEX isn’t really good at timing from what I’ve heard?

Since they have already released a number of the products that they announced would be out in Q3 of this year, I’d imagine it should be out within a few weeks. If I had to guess I’d say they’re waiting longer to get more supply to match the high demand for the sensor. They don’t want a repeat of the V5 rollout where only some teams were able to get it before it went out if stock, so they’re delaying it until everyone can get it at once to level the playing field.