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Author Topic: vAGC Rendezvous Programs (P20)  (Read 4657 times)
irnenginer
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« on: August 30, 2006, 11:29:17 PM »

The next big step for the vAGC, and performing an Apollo 7 mission is Rendezvous. This was a major aspect to what the AGC did. C249 has 10 programs used for Rendezvous:
P17, P20, P34, P35, P37, P38, P75, P77, P78,and P79. The first I will cover is the most complex program in the AGC P20. This thread is meant as a "one stop shop" for P20 development

P20 is used to steer the CSM in such a way as to acquire a second vehicle, such as the LEM, in a optical sighting device. This can be either the CSM optics or the COAS. It also is used to update the second vehicle state vetors either using an optical device or the VHF transponder data.  P20 is unique in that it can run while other programs are run and has several options that can be performed while in operation. The options are
V44E  Set Surface Flag -Causes tracking of the Landing site based on the stored landing site
V45E  Reset Surface Flag- Tracks LEM based on State Vector
V54E  Backup Marking of the LEM (R23)
V56E  Reset Rendezvous Flag - Stops P20
V57E  Marking of LEM (R21)
V58E  Reset Stick Flag - Allow Auto Maneuvering
V67E  W-Matrix Error Display
V76E  Set Preferred Attitude- CSM will orient for using the optics system (And preferred for VHF transponder acquisition)
V77E  Reset Preferred Attitude - CSM will orient to +X (COAS)
V80E  Set State Vector to LM. Data will update LM
V81E  Set State Vector to CSM. Data will Update CSM
V87E  Set VHF Flag. Accept VHF Data
V88E  Reset VHF Flag. Block VHF Data
V93E Reset RENDWFLAG Initialize W-Matrix.

List of Programs Verbs and Nouns Valid during P20
P17,P30,P31,P34,P35,P38,P39,P74,P75,P76,P77,P78,P79,R03,R30,R31,R34,N08,N20,N22,N36,N91,N92,N95,N96,V46,V60,V61,V62,V63,V96.
Note that V48 is not in the list so you have to setup V48 the way you want it before entering P20.

So you want to try it out don't you. Cool

After Launch with Apollo 7 or 8 in LEO, before separation of the SIVB.

V66E

Then after separation translate out from the SIVB to get some distance.

Make sure you have V48 set up and the DAP is active with V46E. Also make sure your in CMC/AUTO.

V37E20E
 
you'll see
F50N18

Enter PRO.

The CSM will orient to acquire the SIVb with the optics. You may even see the SIVb in the telescope sight.

V77E
E
F50N18
PRO

You should now pitch down and see the SIVB line up in the COAS *

* Actually it probably will not line up right. I believe that when the CSM and SIVB separate the SIVB is given some delta V to drift away from the CSM. This causes the AGC State Vector to be off by a small amount. This could be fixed by updating the SIVB State vector using my spreadsheet. But the addresses the update goes into are different.  I have tried updating the SV optically using the V54E but it did not seem to fix it (but I only tried it once).

I will get in to the specifics of P20 in following posts.
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Christophe
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« Reply #1 on: August 31, 2006, 07:57:19 AM »

Quote
This could be fixed by updating the SIVB State vector using my spreadsheet. But the addresses the update goes into are different.

Did you tried P27 to update the SIVB state vector as "other vehicle"?
It should work.
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Swatch
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« Reply #2 on: August 31, 2006, 10:30:31 PM »

That is quite possibly the best description of a vAGC program I've yet to see...  could the same be done for the other vAGC programs?  (they may already be done, in which case, it would be nice to compile them)

The structure I like in this is:

Description of program's use, followed by what the program is actually doing, followed by different options, followed by the list of allowable items, followed by a basic/preliminary howto list.

If this could be done for all the different programs, it'd be a great learning tool.  Great job irengineer.

PS  If anyone can point me to other examples of where this is done, I'd like to see them.
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My Project Apollo Work:
CM Visual
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Propulsion Particle Improvements (Focused on S1B right now, BETA 1.0 has been commited)
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Future Work:  (if it's here, it's deemed unnecessary to upcoming release)

Older Work:  (if it's here, it's fair game to whoever wants to improve)
EMS Implementation (committed: minor flaws, but groundwork is there, needs extensive testing)
EMS scrolls (committed: not refined, but usable)
SM Visual (committed: mesh-finished, texture-60%; possibly revisited in future)
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LRV (committed: mesh-finished, texture-90%; in future a ground up rebuild may be in order, but not on my plans)
irnenginer
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« Reply #3 on: August 31, 2006, 11:59:31 PM »

Did you tried P27 to update the SIVB state vector as "other vehicle"?
It should work.

I tried an update but got a bad result. The AGC reported the the other vehicle was 55nm away instead of a few hundred yards. I am worried that the update spreadsheet may have an issue. Something else to work on too.  Bangs Head

That is quite possibly the best description of a vAGC program I've yet to see...  could the same be done for the other vAGC programs?  (they may already be done, in which case, it would be nice to compile them)

Thank you!

I wrote quite a bit on P53,P54. Its in the forums somewhere. I planned this out because I plan to put similar threads on the other Rendezvous programs. Given their number and complexity I figured this would be a good way to keep track of them all. As they are checked out.

More on P20. One thing I noticed with P20 is when you set V77E the CSM not only goes to the vehicle orientation but will also track the vehicle.

Also to perform V54E in P20:
V54E
 You will See N94, which like P53,P54 you will enter +57.376degrees in R2 using
V22E
+57476E
PRO

Then you'll see V53. line up the Sivb in the sight and
ENTR

You will do this 3 times, the book says to wait about a minute between marks. When you are satisfied with 3 marks enter
PRO

you may also have F50N18 come up during this. just hit ENTR to get back to V53.

Thats it. It "should" use the data to refine the State vector of the vehicle. but I have not seen it accomplish that much so far.
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pattersoncr
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« Reply #4 on: July 12, 2008, 06:04:00 AM »

I considered opening a new topic but I decided to put this here anyway.

I've been doing some research into P20 and I can't get it to work.
I ran the A7 launch scn after reaching orbit, separation, and the first 2 SPS burns, I wait until ~29h point.
(I tried running P17 to setup TPI which I couldn't get to work but that's a different topic.)

I ran P20 (V37E20E)
I get F 50 18
I did the auto-maneuver
I put Optics Mode sw to CMC
The optics point fairly close to the SIVB (based on "cheating" with the docking HUD).
Now I try to update the SIVB SV using V57E but instead of the F 51 I'm supposed to get, I just get a OPR ERR light.
Manually training the optics onto the docking HUD box allows me to see the SIVB in the SXT but I can't figure out how to make marks on it.  As I said, V57 doesn't work and marking without V57 gives me a prog alarm 122 (marking not called for).

Has anybody tried this recently?  More to the point, has anyone got it to work?
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irnenginer
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« Reply #5 on: July 14, 2008, 04:16:50 PM »

V57 is only really usable when using the non-preferred orientation (SC is oriented in the +X for COAS alignment). When in Preferred orientation mode using the optics you go to manual optics and press the MARK. That is why you are getting the OP ERR, it checks for preferred orientation. marks should be made at a rate no less then 15 secods or so for best results. I have managed to do a full rendezous with a SIVB a couple of times and it is almost freaky how good P20 can track a target at considerable distance.
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pattersoncr
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« Reply #6 on: July 14, 2008, 04:29:01 PM »

V57 is only really usable when using the non-preferred orientation (SC is oriented in the +X for COAS alignment). When in Preferred orientation mode using the optics you go to manual optics and press the MARK. That is why you are getting the OP ERR, it checks for preferred orientation. marks should be made at a rate no less then 15 secods or so for best results. I have managed to do a full rendezous with a SIVB a couple of times and it is almost freaky how good P20 can track a target at considerable distance.
When in the preferred orientation, I get a program alarm 00122 (marking not called for) when I try to take marks without entering V57.
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irnenginer
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« Reply #7 on: July 14, 2008, 10:13:37 PM »

Post the scenario and I will check it out. Forget what I said about not needing V57, I was thinking of something else. Duh!

I tried it with my scenario and it worked fine.
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pattersoncr
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« Reply #8 on: July 14, 2008, 10:40:43 PM »

Post the scenario and I will check it out. Forget what I said about not needing V57, I was thinking of something else. Duh!

I tried it with my scenario and it worked fine.

Here you go:

* P20 Test 1.scn (71.83 KB - downloaded 95 times.)
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irnenginer
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« Reply #9 on: July 20, 2008, 10:31:14 AM »

It crashes my orbiter on load. Are you using the latest betas or the latest on CVS?
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pattersoncr
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« Reply #10 on: July 20, 2008, 11:23:16 AM »

latest betas.

No compiler here  Embarassed
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irnenginer
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« Reply #11 on: July 22, 2008, 02:35:07 PM »

I'll give it another shot with the betas.
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