Problem Canadarm2 grapple issue

[Wolf]

I am having some issues in grappling with the SSRMS Canadarm2: in some cases, after positioning the arm for grapple I receive a warning message (see pics) and the arm is unable to grapple. The arm EE is in the correct position and alignment with the grappling fixture. I have also checked the joints values (see pic 2) and they all appear to be within limits...

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[SiameseCat]

There's an error in the wrist roll angle. That's where the "Unable to grapple: Rotation Error: 90.39" comes from.

 

[Wolf]

There's an error in the wrist roll angle. That's where the "Unable to grapple: Rotation Error: 90.39" comes from.

Ok, but why is that error triggered? How do I know what is an acceptable wrist roll angle and what is not?....
I also tried the same grapple with different wrist roll angles but keep getting the same issue.

 

[DaveS]

By using the End Effector grapple fixture alignment target. When the target post is shown as a white dot only in the EE view, then you know have the alignment down and all you have to do is move in towards it.

 

[Wolf]

View attachment 13341

As I said I am correctly aligned to the target, still the error message pops up..

 

[DaveS]

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As I said I am correctly aligned to the target, still the error message pops up..

Well, then the only thing I can think of is that the attitude specified in the config file for that particular grapple point is 90° off from the mesh.

Try playing with those until you get the correct attitude.

 

[SiameseCat]

Ok, but why is that error triggered? How do I know what is an acceptable wrist roll angle and what is not?....
I also tried the same grapple with different wrist roll angles but keep getting the same issue.

The number in the message indicates the rotation error, so you're off by about 90 degrees.

You should be able to use the grapple target to get the wrist roll correct. Like DaveS said, it looks like there's a problem with the settings for that particular grapple fixture, which is why you're having issues.

 

[Wolf]

The number in the message indicates the rotation error, so you're off by about 90 degrees.

You should be able to use the grapple target to get the wrist roll correct. Like DaveS said, it looks like there's a problem with the settings for that particular grapple fixture, which is why you're having issues.

I tried the default "test" scenario released with the addon (Canadarm2 update) to make sure there are no issues related to the grapple fixture used, but I keep getting the same problem..

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I have this issue in different scenarios using different grapple fixtures (including the one above) hence I doubt the problem lies with them...

 

[Wolf]

Another example: trying on Dextre grapple fixture:

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[Wolf]

"Here is what I found: I installed ISSAtoZ and Canadarm2 with all the rerquired addons on another Orbiter install and everything worked ok.
I then installed the latest Dansteph "UCGO30_2010_20140109" and since I ve done that I encountered the same problems with Canadarm2 ("rotation error" and "unable to grapple" messages) I had on the original Orbiter install. I then deleted all the UCGO modules and now the Canadarm2 seems to be working fine again.
There is probably some conflict between the two addons that causes Canadarm2 to be "unusable" but I have no idea what exactly is triggering the issue.
I thought this info might be useful to you since other users might have both addons installed and face the same problems I had".

PMed to the author and reporting here in case somebody had the same issues and/or is willing to verify if there is actually any incompatibility between Canadarm2 and UCGO-UMMU...

 

[SiameseCat]

Are there any UCGO vessels in the scenarios where you get rotation errors? I haven't had the time to investigate this, but I'm really surprised that UCGO is interfering with the SSRMS.

 

[Wolf]

Are there any UCGO vessels in the scenarios where you get rotation errors? I haven't had the time to investigate this, but I'm really surprised that UCGO is interfering with the SSRMS.

None of the scenarios has any UMMU or UCGO vessel.
Even using the "default" ISS AtoZ scenario I experience the same exact thing: Install UMMU or UCGO and the arm won't be able to grapple. Delete UMMU/UCGO (or run the same scenario on an Orbiter install without UMMU-UCGO) and the arm "by magic" works perfectly again...:hmm:

The fact that nobody else reported this makes me believe something is wrong on my end. I don't know how popular Canadarm2 is (it should be since IMHO it's definetly a "must have" for ISS users) but it would sound strange to me that nobody has both UCGO/UMMU and Canadarm2 installed..

 

[SiameseCat]

I tried using the SSRMS with UCGO installed, and I didn't have any problems, so it does seem like an issue on your end. The rotation angle is calculated from the SSRMS and target attachment points, so unless something is modifying the attachment points, I'm not sure what's going on.

 

[Wolf]

Thanks Siamesecat
It is probably some other thing then (maybe one of the modules). I'll try to further investigate it...