Reliability of Pixy Camera?

[AlexanderLuke]

Originally Posted by electroken

I found it to be a bit touchy to set up, but once calibrated to the lighting in each venue it worked well.

We did change the lens from the stock one (75 degree horizontal field of view) to I think 51 degrees field of view.

Two things:

1. What settings would you alter in order to get the best performance? Actual numbers on specific settings would be very helpful, I'm curious to know what you did to have the best performance possible.

2. What benefits did you find in changing the lens? What issues did you experience that made you look into changing the lens?


To anyone else who ran the Pixy this past year or have other experience, please feel free to chime in on your answers too.

[nardavin]

Thanks everyone for all of the great responses!

I just have one other question. Is there a way to pull the raw footage from the camera in the case that more advanced vision processing is needed? It looks like it may be possible via a USB connection but I don't see anything specifically referring to it in the USB api docs.

[electroken]

Originally Posted by AlexanderLuke

Two things:

1. What settings would you alter in order to get the best performance? Actual numbers on specific settings would be very helpful, I'm curious to know what you did to have the best performance possible.

2. What benefits did you find in changing the lens? What issues did you experience that made you look into changing the lens?

The Pixy is primarily a color sensor, so there is a balance to be found between consistently seeing what you want it to see with the exclusion of everything else. There are settings within the Pixymon calibration program to teach it how close is close enough to be considered a target, camera exposure, white balance, etc. We had some control over potential interference sources because we were looking for the specific orange of our targeting LEDs. We chose orange because it was not present in the field lighting. Others use green, YMMV. I don't know specific calibration numbers, as the robot is hibernating at the school.

The lens choice was also made to reduce the potential sources for false targeting. Using the Pixymon program to see what the camera saw, the 51 degree lens gave us the best view of the field with the least view beyond it.

The system was not perfect and needed tweaking along the way. The scrolling LED display along the arena perimeter at champs was occasionally orange and had to be considered. We also found that the end wall diamond plate at champs was highly polished, far more so than at our district events. That caused or robot to shoot at its own reflection once in autonomous (funny in hindsight). After teaching it to turn 30 degrees to starboard before looking for a target that was no longer an issue.

The Pixy can actually be set to look for 7 simultaneous colors. Who knows, that may be useful this year.

[Greg McKaskle]

I haven't used the pixy cam on an FRC robot, but I purchased one and I'll be using it for another robot competition. It has worked well in my initial testing with controlled lighting.

As stated. It is really more of a color-proximity sensor, a highly optimized and specialized sensor that does one thing well. If that is useful in the game, make use of it. If not, it is actually a pretty good exercise to make your own pixy cam using a USB camera and a little bit of processing code and extend it to do some additional measurements on the particles. But at that point, there isn't much need to incorporate the pixy cam. Just build your own. It is a great learning opportunity.

The optimization is the hard part. But I'm pretty sure most can make it fast enough for what they need on the robot. We aren't needing to measure the wing-beat speed of an unladen European swallow, are we?

Greg McKaskle

[Gdeaver]

Ok, I think we may have to revisit the pixy cam. Our judgement may have been premature. We went with grip on a Pi2b and an IP camera. The programmers are working on Opencv on a PI3 with IP camera and a native Pi camera. The difference is color blob detection vs object detection. The Pixy cam is a much simpler solution. One can not have enough tools in the tool box for next season. It seams that machine vision is a requirement for FRC teams that aspire to play at a high level. Our best trained operator could aim and shoot at best in 7 to 8 seconds. Our auto aim and shoot was average of 3 to 4 seconds and more consistent.

[Alsch]

It's nice to see how far the CMUcam platform has come. I remember trying to fuss with the old rs232 ones years ago.
Has anyone looked into the OpenMV camera? I don't hear as much about it, but I've been using one for a while and it's pretty nice, I wonder how they compare with one another. (buying more than one $60+ dev board at a time is somewhat difficult to justify to oneself and ones wallet.)

[Bpk9p4]

Originally Posted by Alsch

It's nice to see how far the CMUcam platform has come. I remember trying to fuss with the old rs232 ones years ago.
Has anyone looked into the OpenMV camera? I don't hear as much about it, but I've been using one for a while and it's pretty nice, I wonder how they compare with one another. (buying more than one $60+ dev board at a time is somewhat difficult to justify to oneself and ones wallet.)

do you know the updated rate for the OpenMC Camera

[Alsch]

Originally Posted by Bpk9p4

do you know the updated rate for the OpenMC Camera

If you mean the price, it's $75. If you are referring to like, framerate or baud or something then I'm pretty sure that they're configurable to whatever
<complaining>Tangentially, I myself purchased my own unit through the Kickstarter campaign, so it was at a discounted price of ~$60. They then tell us that they encountered production issues and had to spend the shipping fees they had charged on the problem, so we all needed to spend an extra $12 to get our already-bought boards actually sent to us, ultimately eliminating the discount we received for backing the campaign.</complaining>