Date: Fri, 26 Aug 2022 15:39:33 -0600
Subject: Re: [sloan-25mlog 6226] Re: 2.5m obslog 20220825 (SJD 59817)
From: "Daniel Oravetz"
>> - On design 57351, we had a collision on fiber 1093. We were unable to
>> recover
>> from it fully. The whole operation cost us about 30 minutes.
>
> Hello Dylan and Dan: Can you please elaborate more on the collision?
> Especially whether the fiber 1093 is fully folded now?
No, 1093 was not folded when we left since we could not execute any moves
in its beta axis.
It was during a 'reverse' command that 1093 complained of a collision
detection. Based on the jaeger snapshot it was not physically near
anything, so it appeared to be a false collision detection.
We tried many iterations of the usual mitigation measures including
'explode' commands and 'goto' commands (in both axes and in individual
axes), but 1093 would not move in beta and the corresponding jaeger error
messages indicated that 1093's beta axis was locking things up.
Using an 'unwind --force', all positioners except for 1093 and one
positioner to the left of 1093 at the edge of the array were able to
return home and were folded. We were able to move 1093 in the alpha axis
only at this point and moved it over to near one of the fiducials, but we
were still never able to execute any move of 1093's beta axis.
Once we moved 1093 in alpha far enough over to a fiducial, then we were
able to send the other remaining positioner home manually. That left only
1093 in an unfolded configuration (I think the last position for 1093 was
alpha=160, beta=45). We disabled 1093 in that unfolded configuration and
proceeded the rest of the night without issues.