Advanced Grabbing Unit does not release (nor swivel) from a grabbed docking port

[Skyrocket]

Some time ago I hauled a quite decent mining and refueling space station to Minmus orbit to foster my interplanetary ventures.

To do this I built a tug vessel with a lot of dV mainly consisting of a large fuel tank, four Nerv rockets engines and an Advanced Grabbing Unit (instead of a docking port) for lugging stuff around. The decision to use the Advanced Grabbing Unit instead of a docking port was done because I planned the vessel to be reused as an asteroid pusher once the space station was finished.

The station was split in two parts, hauled to Minmus and assembled there, using the vessel mentioned above. So "grabbing" and "releasing" worked fine at least once.

After the station was completed, the tug vessel was left "docked" at the space station by grabbing a docking port. This worked fine.

The problem is: I cannot release/undock the space station's docking port. Whenever I click on "Release" on the action menu of the AGU nothing happens, the claw remains attached. Immediately after clicking "Release" the button "Release" and "Free pivot" disappear.

If I click "Disarm" the animation covers the AGU, a click on "Arm" reveals the closed claw again, and "Release" and "Free pivot" buttons reappear.

Then again clicking either "Release" or "Free pivot" do not do anything (no free pivoting either). I tried this repeatedly, also tried restarting the game and reloading from a save, of course.

Question: Is there any way to detach the claw and perform my asteroid mission? Or is my tug vessel doomed to stay clawed to the mining station forever?

My last resort will probably be hacking the sfs file and selectively overheating the docking port part of the space station the claw is attached to. But I'd rather keep the docking port...

Edited May 1, 2018 by Skyrocket
Typos

[Serenity]

9 hours ago, Skyrocket said:

The problem is: I cannot release/undock the space station's docking port. Whenever I click on "Release" on the action menu of the AGU nothing happens, the claw remains attached. Immediately after clicking "Release" the button "Release" and "Free pivot" disappear.

Did you try to right click on the docking port and see if you can click undock or something?

If thats not the case then you might be experiencing a bug where the part is stucked to a certain state.

Try quicksaving/quickloading and maybe even go to persistent.sfs find the klaw or port and check its state.

[Lego_Prodigy]

Ill try to replicate this, but the situation of a stuck Klaw and port make me nervous for my future ideas

Didnt work

[Serenity]

10 hours ago, Lego_Prodigy said:

Ill try to replicate this, but the situation of a stuck Klaw and port make me nervous for my future ideas

Didnt work

If you have the new parts you could hide it with an upside down engine plate, and when you decide you need the klaw you deploy the engine plate

example: https://imgur.com/a/bn2BrJq

It should work and its just one of the many designs, there maybe another way to do it but thats what i can think right now.

Edited May 2, 2018 by Boyster

[Gargamel]

Try the kerbal approach to this. 

Quicksave first.

Click release, the unarm, then time warp and see if they drift apart or explode.   If they drift apart, good.  If they explode, reload the quicksave. 

Probably won't work, but it's worth a shot.

 

Little bird in the back of my head is telling me this is an old old bug.  Never grab a port with a Klaw.  Grabbing a Kerbal with  a Klaw used to shatter the universe IIRC, but they fixed that one. 

[Skyrocket]

14 hours ago, Boyster said:

Did you try to right click on the docking port and see if you can click undock or something?

If thats not the case then you might be experiencing a bug where the part is stucked to a certain state.

Try quicksaving/quickloading and maybe even go to persistent.sfs find the klaw or port and check its state.

Unfortunately that does not work, on the "station side" docking port no "Undock" option appears. (But this is consistent what I experienced with regular docking ports, in my experience undocking is typically done on the docking port of the "far" side of the main vessel, the one attached to the vessel to undock.)

I've had a long look at the sfs file but I'm not sure how I could unclaw the claw in the file. There's no obvious way to do that.

10 minutes ago, Gargamel said:

Try the kerbal approach to this. 

Quicksave first.

Click release, the unarm, then time warp and see if they drift apart or explode.   If they drift apart, good.  If they explode, reload the quicksave. 

Probably won't work, but it's worth a shot.

 

Little bird in the back of my head is telling me this is an old old bug.  Never grab a port with a Klaw.  Grabbing a Kerbal with  a Klaw used to shatter the universe IIRC, but they fixed that one. 

Tried that, did not work. They keep attached no matter how long or how fast I time warp.

Bummer to hit an old bug. I guess I will probably need to explode that docking port after all.

[Gargamel]

31 minutes ago, Skyrocket said:

Bummer to hit an old bug. I guess I will probably need to explode that docking port after all.

Sit on it for a bit.  Somebody more knowledgeable might come around in the (US) daylight hours.  

[4x4cheesecake]

Well, recently I had a problem with two dockingports which doesn't want to decouple. The reason for this was this pretty common "clipped cubic strut to surface attach something that doesn't want to surface attache". Somehow this strut got duplicated, caused a massive NRE spam and somehow prevent the undocking. To solve this I had to edit my savefile and delete this specific strut (it was the very last part in the file) and everything was fine again.

Also, I had a claw that wasn't able to swivel and the reason for this one was pretty simple: an autostrut going through the claw into the grabbed asteroid.

So you may want to check your console log while releasing the claw and check your autostruts.

[Gargamel]

16 hours ago, 4x4cheesecake said:

Also, I had a claw that wasn't able to swivel and the reason for this one was pretty simple: an autostrut going through the claw into the grabbed asteroid. 

@Skyrocket, this may be the cause.   Go through your vessel and turn off all the autostruts, then try undocking. 

[Skyrocket]

16 hours ago, 4x4cheesecake said:

Well, recently I had a problem with two dockingports which doesn't want to decouple. The reason for this was this pretty common "clipped cubic strut to surface attach something that doesn't want to surface attache". Somehow this strut got duplicated, caused a massive NRE spam and somehow prevent the undocking. To solve this I had to edit my savefile and delete this specific strut (it was the very last part in the file) and everything was fine again.

Also, I had a claw that wasn't able to swivel and the reason for this one was pretty simple: an autostrut going through the claw into the grabbed asteroid.

So you may want to check your console log while releasing the claw and check your autostruts.

 

6 minutes ago, Gargamel said:

@Skyrocket, this may be the cause.   Go through your vessel and turn off all the autostruts, then try undocking. 

Unfortunately not. I enabled autostrut visualization, and no autostrut was anyway near the clawed vessel. To make sure no other autostruts on the station interfered I disabled all autostruts on the station and also undocked another vessel with landing gear. Releasing the claw did not work either.

Also thanks for the suggestion to check the console. There is no output at all when clicking Arm/Disarm/Release, but if I click Free Pivot the game displays a "Null reference exception: Object reference not set to the instance of an object".

Playing around with the Object Thrower I entertained myself for 30 minutes throwing small spheres at the Grabbing Unit. Hilarious flexing, vibrations and sometimes spontaneous combustion effects ensued (depending on angle and target). Amazing how flexible and frustrating how powerful the Claw is. And it never, ever lets go, even if everything else around it explodes.

However, I managed to selectively blow up the docking port. Once it's gone the vessel is undocked. After it was free I tried to dock a fuel tank, worked fine - and releasing it worked as well. However, Free Pivot seems to be stuck. Strange.

OK, I will probably go this route and call the docking port an ex-docking port. Easier and cheaper than setting up a new asteroid pusher.

[Gargamel]

Well, when all else fails, hit it with a Hammer.   They tried that on Apollo 12 to get their camera to work, but with less success. 

[StrandedonEarth]

If you have KIS/KAs installed, you could tack on a new docking port later..