Undocking with target heading set can cause craft to whip around.

@swope Thanks! Let me know if you can still repro the issue.

Looking forward to trying the fix in beta.

@swope I've got a fix ready, and you are right, it is nav-sphere related. Thanks a lot for your help!
 
FYI: I uploaded another bug report and merged it w/this one (linked below), which is ready to go while doing minimal repro steps. I also updated the title to reflect the issue I ended up fixing (original was : RCS goes bonkers when docking)

Fixed in: 95ced2840dd9418d9ce885bd71dba62932d6d447

This post has been merged with this post.

@PhilipTarpley, I'm back to thinking it's the nav sphere and/or the vehicle axes. After docking I used nav sphere to point the craft at the sun to maximize solar panel efficiency (and the batteries weren't charging despite 99% efficiency on all 8 panels and 10x time warp and the nav sphere turned off to prevent the gyros from draining the battery to keep the pointing.)

Then I used [ to switch control to the other capsule, and immediately the craft rotated to point in a previous orientation. I don't think changing the pod-in-command should suddenly reorient the vehicle. That probably will catch people off guard.

@PhilipTarpley - the other conjecture that occurred to me is that there might be a bug in the calculation of moments or angular velocity that is triggered when the docking completes. Essentially the docking is an inelastic collision of two bodies with low angular rates and low relative velocities, yet following the collision there is suddenly a change in angular rates. If there's a change in velocity, it wouldn't be apparent because the camera tracks the CoM. I haven't been watching the orbit parameters to see if they jump.

@swope Awesome instructions, thanks! I was able to repro the situation. It seems a bit fishy to me...I'm going to investigate.

@PhilipTarpley - last night when I tested, I did a new launch, starting in orbit.

1. Set nav sphere to track pitch 0, heading 0.
2. Undock.
3. [ to switch crafts.
4. enter to set nav sphere on pitch 0, heading 180.
5. t for translate mode.
6. Back up to be outside of "undocking" state.
7. Go to map mode to choose docking target.
8. w to head toward the other craft.
9. After docking, the combined vehicle starts to pitch and yaw.

I'm guessing it has something to do with leaving the nav sphere tracking turned on in the Bob capsule. When the Alice capsule re-attaches, the combined craft suddenly has a new nav sphere heading command, but it inherits the orientation of the other craft.

@swope Regarding item 3...I cannot reproduce this. I might not be going through the correct steps though. Here is what I'm doing.

1. Load this bug report's sandbox.
2. Turn on translate mode and hit w to move into docking position.
3. Dock.

When I do this, the new combined craft takes no auto-pilot action. What am I missing?

Thanks a lot for your help...I really appreciate it.

@PhilipTarpley - I just repeated the docking I was trying to do in earlier beta 0.7.0.1, and I'm not having the same problems with 0.7.0.5.

1. The RCS does not go haywire when I get in close.
2. The docking rings tolerate being slightly off-axis.
3. When the craft docks successfully, the orientation changes suddenly to the other craft's, and the autopilot immediately tries to flip the combined vehicle around. This is still happening, but I think I understand it.
4. w and s seem to be working correctly at all times now. The orientation is correct -- that is, w translates toward the other craft.

@swope You mentioned here that you cannot repro the issue w/this sandbox (in item 4).

I was able to create a likely undesireable situation with the following steps, is this perhaps what you saw?

1. Load this bug report's sandbox.
2. Turn on translate mode and hit W to move into docking position.
3. Dock.
4. Target prograde (or any sufficiently different direction w/nav-sphere).
5. Wait for craft to re-orient to target direction.
6. Take control of other craft
7. Undock craft

Craft will immediately swing to target its prograde.

Edit - After watching your video, it doesn't appear that is what was happening...

Dev Notes: More information is here