Camera Code Update

[Alan Anderson]

Originally Posted by Tyr333

I've noticed that when the camera is in a search, if the camera is resetting its pan for a new sweep:...and if the camera sees the light during this motion of resetting the pan to its minimum, when it arrives at this new pan position, the camera tilts down. It continues to search at this lower tilt, reaches the maximum pan, tilts back up, sweeps to its minimum pan, sees the light during this trip, and tilts down again. It continues this loop and never tracks the light...What can we do to fix this?

You can change the search pattern code to do a zigzag sweep instead of always going left-to-right. That way it will never be panning too fast to stop when it sees the light, and it won't need to restart the search immediately upon glimpsing and then losing it.

Here's an overview of one way to go about it. Where it tests for the pan value being greater than the maximum limit, set a flag instead of resetting to minimum. Add a similar test for the pan value being less than the minimum and reset the flag if it is. Where the code adds the step size to the current pan value, have it subtract instead if the flag is set.

[Kevin Watson]

I've uploaded version 2.2 of the bells & whistles camera code. See the attached document for a list of changes. As it's very close to the ship date, I would caution everyone to think really, really hard before ripping open your nearly complete code and dumping my changes in. For this reason I'm not sure if I'll add a link to this code on my website before the ship date. I guess I'll wait to see what the Chief Delphi crowd thinks. As always, please let me know if you find any bugs in the code or documentation. Anyway, here's a link: http://kevin.org/frc/frc_camera_22.zip.

Edit: I found a bug in the search code I published above, so don't use it.

-Kevin

[Tom Bottiglieri]

I found a bug in the old search code. Not sure if someone has seen this before or not. We have our camera mounted upside down. So, top is bottom and left is right. The camera still tracks the right way because the image is flipped, but the search code looks at the floor instead of the ceiling. When we have the target in front of the robot and elevated a bit, the search code freaks out. As it transitions from its max tilt pwm to its min tilt pwm, it does a diagonal. While traveling this path, it gets a new t packet (I see the red light on the camera flash) as it passes where the light is. As soon as it gets to the other corner, it doesn't see the light anymore, but it continues to drop to the middle tilt search pwm and scan on that level, at which it does not get a new t packet.

This problem will go away when we change the search code to our own algorithm, but I still think it is a bit of a problem.

[Tom Line]

I'd like to make one suggestion - we've found the common sense says the light is probably closest to the position that you lost at it. If you comment out the "New_Search = 1" line in the old code, the camera will just continue searching from it's current location.

Generally it results in a much quicker lock, because if it was only a temporary loss of the light (say a robot drives in front of you) the camera may well catch the light on the next pan, rather than resetting the tilt completely and starting a new search.

This is especially true when the robot is under the light to score. It also fixes the issue some teams are having where the camera "freaks out" and starts doing the tilt down then pan that someone else mentioned here.

[jdejoannis]

Originally Posted by Kevin Watson

I've uploaded version 2.2 of the bells & whistles camera code. See the attached document for a list of changes. As it's very close to the ship date, I would caution everyone to think really, really hard before ripping open your nearly complete code and dumping my changes in. For this reason I'm not sure if I'll add a link to this code on my website before the ship date. I guess I'll wait to see what the Chief Delphi crowd thinks. As always, please let me know if you find any bugs in the code or documentation. Anyway, here's a link: http://kevin.org/frc/frc_camera_22.zip.

Edit: I found a bug in the search code I published above, so don't use it.

-Kevin

Don't use what? Are you saying not to use v2.2 altogether?

[Kevin Watson]

Originally Posted by jdejoannis

Don't use what? Are you saying not to use v2.2 altogether?

No, I meant the snippet of search code I included in this posting. The problem is that when a new search is initiated, the servo PWM values could be initialized to values outside the min/max PWM range set in the code, which could lead to wacky behavior. I haven't had time to look at it yet, but the same bug may be present in older code. The new search code is easier to read and comprehend, should work better, and provide a better foundation for those that want to modify it for their specific needs.

-Kevin

[jdejoannis]

Does line 365 need to be changed to Tilt_Min?

[Kevin Watson]

Originally Posted by jdejoannis

Does line 365 need to be changed to Tilt_Min?

No, I changed it to Tilt_Center_PWM so that you can specify a starting angle for searches other than Tilt_Min_PWM, which is currently zero degrees. The comment associated with TILT_CENTER_PWM_DEFAULT in tracking.h was updated to reflect this change. Thanks for helping with the bug hunt.

-Kevin

[jdejoannis]

Originally Posted by Kevin Watson

No, I changed it to Tilt_Center_PWM so that you can specify a starting angle for searches other than Tilt_Min_PWM, which is currently zero degrees. The comment associated with TILT_CENTER_PWM_DEFAULT in tracking.h was updated to reflect this change. Thanks for helping with the bug hunt.

Are you sure? I believe its line 339 that pertains to the initial position for a new search. Line 365 is for when the tilt has exceeded its max. Tilt_Min_PWM is not mentioned even once within the search portion of the code.

Jason

[Kevin Watson]

Originally Posted by jdejoannis

Are you sure? I believe its line 339 that pertains to the initial position for a new search. Line 365 is for when the tilt has exceeded its max. Tilt_Min_PWM is not mentioned even once within the search portion of the code.

Jason

I'll have a look...

-Kevin

[Kevin Watson]

Originally Posted by jdejoannis

Are you sure? I believe its line 339 that pertains to the initial position for a new search. Line 365 is for when the tilt has exceeded its max.

Both lines of code return the tilt servo to the starting tilt angle, which may or may not be zero. The code as it is currently configured, does not change the tilt angle from 30 degrees because the vertical field of view of the camera from that angle can see the light from most of the field, including the entire starting area.

Originally Posted by jdejoannis

Tilt_Min_PWM is not mentioned even once within the search portion of the code.

Yes, I know. Tilt_Min_PWM is only used by the tracking algorithm to establish the minimum PWM value that the tracking algorithm will attempt to drive the servo to. Tilt_Center_PWM establishes the same baseline while tracking.

I realize that this may be confusing, so perhaps I need to consider changing the name(s) to something else.

-Kevin

[jdejoannis]

Originally Posted by Kevin Watson

I realize that this may be confusing, so perhaps I need to consider changing the name(s) to something else.

I got you now. You want it to search from 30-90 degrees and track from 0-90 degrees. I don't really see why they should be different ranges. Could just as well set the min to 30 rather than 0 (and use it as the starting point). This will work fine though, thanks!

Jason

[Kevin Watson]

How's it going with this code? Any problems, complaints, etc? Should I go public with it? Does Diet Pepsi taste better that Diet Coke?

-Kevin

[DanDon]

Originally Posted by Kevin Watson

How's it going with this code? Any problems, complaints, etc? Should I go public with it? Does Diet Pepsi taste better that Diet Coke?

-Kevin

So far, after small amounts of testing the new code (i.e. seeing if it searches and tracks, and testing the menus), I have not found any bugs.

[Tom Bottiglieri]

Originally Posted by Kevin Watson

How's it going with this code? Any problems, complaints, etc? Should I go public with it? Does Diet Pepsi taste better that Diet Coke?

-Kevin

For some reason I was under the presumption that the tracking software was broken. I'll start testing tonight.