Subject: Re: [sdss3-25mlog 895] telescope slew overshoot - addendum to log
From: Dan Long
Date: Wed, 31 Oct 2012 08:09:30 -0600
Hi Dan,
   This is an example of what happens when a TCC slew is superseded =
while in progress, and is normal.  It isn't necessarily obvious that =
loading a cartridge would cause a slew to recalculate, but that is what =
happened here. Since the slew to 30 was issued from the TCC rather than =
the MCP it is not the same thing as the other overshoots.  Here is the =
view of events from the TCC's world.
The move to 30 is started:
2012-10-31 12:44:12.816Z 203022 1 > Started; Cmd=3D"track 121,30 mount =
/rota=3D0 /rotty=3Dmount"
2012-10-31 12:44:13.264Z 203022 1 I =
AxisCmdState=3D"Drifting","Drifting","Drifting"
2012-10-31 12:44:16.704Z 203022 1 I SlewAdvTime=3D1.92
2012-10-31 12:44:16.947Z 203022 1 I MoveItems=3D"YYYYYYYYY"; =
SlewBeg=3D4858404294.56; SlewDuration=3D37.62
loadCartridge sends set instrument to the TCC:
012-10-31 12:44:26.304Z 203023 1 I Text=3D"reading file: =
TINST:DEFAULT.DAT"
2012-10-31 12:44:26.324Z 203023 1 I Text=3D"reading file: =
TINST:V_CA1_5177.DAT;"
2012-10-31 12:44:26.333Z 203023 1 I Text=3D"reading file: =
TINST:I_CA1_SPECTRO.DAT;"
.
.
.
2012-10-31 12:44:33.800Z 203022 1 I SlewSuperseded
2012-10-31 12:44:34.304Z 0 0 I =
AxisCmdState=3D"Drifting","Drifting","Drifting"
2012-10-31 12:44:37.750Z 0 0 I SlewAdvTime=3D1.92
2012-10-31 12:44:37.751Z 0 0 I MoveItems=3D"NNNNNNNNN"; =
SlewBeg=3D4858404312.40; SlewDuration=3D34.66
2012-10-31 12:44:37.752Z 203023 1 I Inst=3D"SPECTRO"; InstPos=3D"CA1"; =
GCView=3D"5177"
The recalculated slew ends up sending the altitude to 34 before =
returning to 30:
2012-10-31 12:44:42.704Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,28.758,0.000
2012-10-31 12:44:44.705Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,30.480,0.000
2012-10-31 12:44:46.706Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,31.881,0.000
2012-10-31 12:44:48.704Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,32.963,0.000
2012-10-31 12:44:50.705Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,33.724,0.000
2012-10-31 12:44:52.706Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,34.166,0.000
2012-10-31 12:44:54.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,34.288,0.000
2012-10-31 12:44:56.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,34.089,0.000
2012-10-31 12:44:58.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,33.570,0.000
2012-10-31 12:45:00.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,32.732,0.000
2012-10-31 12:45:02.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,31.664,0.000
2012-10-31 12:45:04.624Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,30.794,0.000
2012-10-31 12:45:06.625Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,30.242,0.000
2012-10-31 12:45:08.625Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,30.011,0.000
2012-10-31 12:45:11.185Z 0 0 I TCCStatus=3D"SSS","NNN"; =
TCCPos=3D121.000,30.000,0.000; AxePos=3D120.999,30.000,0.000
2012-10-31 12:45:13.025Z 0 0 : SlewEnd
2012-10-31 12:45:13.185Z 0 0 I =
AxisCmdState=3D"Tracking","Tracking","Tracking"
		Cheers,
		   Dan
On Oct 31, 2012, at 7:38 AM, Daniel Oravetz wrote:
> This morning after closing we initiated the slew from 6 degrees =
altitude
> to 30 degrees and watched as the telescope slewed past 30 degrees to =
~34
> degrees and then reversed direction and settled at 30 degrees. =
Attached is
> a screen shot of archiver data for the tcc.axePos keyword which =
details
> the overshoot behavior.
>=20
> I think it's worth mentioning that I issued a loadCartridge command =
after
> the slew had commenced. We had mounted a BOSS cartridge in order to =
leave
> all APOGEE cartridges in the bay available for plugging and I issued =
the
> loadCartridge before we began the 20 BOSS biases and the lone dark. =
Even
> though it's possible to take BOSS biases and darks while a bright
> cartridge is mounted via the 'bypass' feature in the SOP window, it
> doesn't hurt to load the cartridge and avoid having to look at the
> cartridge mismatch between guider and mcp within STUI (purely =
cosmetic, I
> suppose). Nevertheless, the loadCartridge command was issued at:
>=20
> 2012-10-31T12:44:39.415074 	17 	5177 	A 	56226 	1
>=20
> I guess the take-away is that the slew may have overshot as a result =
of
> the loadCartridge issuance interrupting something during the slew and
> perhaps it's worthy of further investigation.
>=20
> =
Dan___________________________________________________=
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