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Author Topic: A few modifications to the AGC code  (Read 3539 times)
RMaia
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« on: April 21, 2005, 09:41:03 AM »

Yes, I was working on a lot more improvements, but unfortunately I'm afraid that I won't be able to find the appropriate time for finishing all that I started within a short time.Sad
So, I thought about releasing what I already have done, which is basically just the new lunar ascent auto-pilot (LMAAP v4) and a more descriptive manual of the AGC features implemented.
I did "migrate" the autopilot code from the NASSP 6.2 code to the newest code available on CVS, so I guess it can be considered up-to-date. The manual however, is based on the NASSP 6.2 features and the LMAAP v4, so if there were any added features to the AGC code since that version, they are not included.

If there is interest in having the original modiyiable (*.doc) file for the manual, so new updates can be added to it, please feel free to contact me and I will send you the file.

Also, I called the AGC with the improvements AGC 2.0, as it is referred thorugh the manual. If that denomination is not appropriate, again, please fell free to tell me.

Here's a summary of the changes I made:

- LMAAP V4:
This is the Lunar Module Ascent Auto-Pilot I have developed. The version included with this release is the  latest, Version 4. It is implemented as the P12 in the LM AGC.

- New noun codes. These include:
 Noun 16, Noun 17, Noun 28, Noun 32, Noun 42, Noun 46, Noun 81 and Noun 82 for both the CM and LM AGC
 Noun 11, Noun 45, Noun 74, Noun 75 and Noun 76 for the LM AGC

Since I understand there's being a lot of changes going through the CVS sources at the moment. And given the fact that I had several missing resource pointers in the lempanel.cpp (version from 17/04/2005 1:14PM), which prevented me from compiling the modules. I thought about making the changed files available separately, so someone with a better understanding of CVS can then integrate it into the main sources. Can that be done??

Anyway, here are the links to the manual and the cpp files.

http://www.extreme-aero.com.br/oldver/misc/AGC20mods.zip (28Kb)
http://www.extreme-aero.com.br/oldver/misc/AGC20manual.pdf (223Kb)

Please tell me what you think.Happy
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Rodrigo Merce Maia

- Sometimes, simplicity is the best answer to complexity.

Physics is FUN!
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« Reply #1 on: April 22, 2005, 03:27:34 AM »

Looks good RM.

Any chance you having the code for P 30?

For CM/LM stack.
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Tschachim
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« Reply #2 on: April 22, 2005, 10:14:57 AM »

I fixed the LM so you can build and run it, but the DSKY is "out of order" at the moment because of the new CSM panels.
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Tschachim
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« Reply #3 on: April 22, 2005, 10:29:20 AM »

Quote from: RMaia
If there is interest in having the original modiyiable (*.doc) file for the manual, so new updates can be added to it, please feel free to contact me and I will send you the file.


Hey, that manual is quite cool, perhaps you can put the .doc-file into CVS, in the "Orbitersdk\samples\ProjectApollo\Doc" folder, so the deveopers can work with it (or mail me, then I put it in).

I wrote the documentation of my stuff ( http://www.ibiblio.org/mscorbit/phpBB2/viewtopic.php?t=131 ) in Docbook XML and built the HTML and PDF docs from that, online help (.chm) would be possible, too. Perhaps I should try to do something similar for Project Apollo...

Cheers
Tschachim
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movieman
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« Reply #4 on: May 19, 2005, 03:28:00 PM »

These changes are now in CVS, but since the LEM DSKY doesn't work I can't properly test them... I know it builds and I can launch Apollo 11 from Earth, but that's about as far as I got Happy.
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Tschachim
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« Reply #5 on: May 27, 2005, 12:05:37 PM »

I pasted the CSM DSKY on the left LM panel, so the LM now has an "ugly but working" DSKY on the left, non-illuminated panel, just for development and testing of the LGC.

I tried the ascent autopilot starting with the "10) Apollo 11-  ready for lunar liftoff" scenario. I left the N76-values unchanged, just entered a 2 minutes countdown. The beginning of the ascent was fine as far I can judge, but after a few minutes (I think after this "-52 pitch phase") the LM begins to do somersaults, perhaps someone can have a look at it, I'm not sure if I used it correct...

Thanks
Tschachim
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Tschachim
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« Reply #6 on: May 27, 2005, 03:28:05 PM »

I think the problem is that the -52 pitch is never reached. If you change the Prog12 function like this:
Code:

case 17:
//
// Pitchover. Here we aim for a pitch of -52 degrees
//
npitch = -53; // otherwise -52 is never reached

Thrust = (Mass * PMI.data[0] * (npitch - pitch)) / (Size);

it doesn't "hang anymore at ProgState 17. But after the burn is finished, the orbit PeD is too low and I'm crashing in the moon...  Confused

Since I have no clue about autopilots, I don't want to commit any changes, but perhaps this helps.
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FordPrefect
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« Reply #7 on: May 28, 2005, 06:57:35 AM »

Well, I have no clue about RMaia's ascent auto pilot code, but AFAIR historically the pitch forward to -54 happened just ten seconds after lift-off, which was reached some 3 seconds later, from then on the pitch was gradually increased (pitching more forward) to adjust the ascent climb rate at about 50 m/s. Then when reaching about 42 k (13.5 km) altitude, ascent rate was terminated, which resulted in an initial apolune of 15 km above the surface (which became the perilune after engine shutdown).

I have done the ascent in a Apollo 17 scenario, with a customized sound file for the ascent, and by doing it like described above, I could very closely match the actual historical time/altitude callouts.
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My Project Apollo work in progress:
* New detailed Lunar Module Ascent stage with virtual cockpit (VC currently planned as eye candy only) 18 % done

My Project Apollo work to be continued:
* new Service Module SPS engine bell
* various Saturn V textures, exhaust textures
* SIM Bay for the SM


My long-term plans are to create a:
* New detailed Lunar Module descent stage (eventually models of all flown LM's)
* New F-1 engines for the S-1C stage showing the foil (batting) insulation
* New LUT and launch pad (if nobody else does it)
Tschachim
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« Reply #8 on: May 30, 2005, 02:49:22 PM »

Quote from: FordPrefect
I have done the ascent in a Apollo 17 scenario, with a customized sound file for the ascent, and by doing it like described above, I could very closely match the actual historical time/altitude callouts.

With the current CVS version or the released 6.4.x version?
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FordPrefect
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« Reply #9 on: June 01, 2005, 05:39:49 AM »

Quote from: Tschachim

With the current CVS version or the released 6.4.x version?


Sorry for the confusion Tschachim. I am using the released 6.4.2 version, BUT my previous post is describing the ascent when I was flying it manually, not using the ascent autopilot. I have customized and synchronized an original soundfile from the real Apollo 17 lunar lift-off as a wave file for the lunar-ascent.wav of the Project Apollo sounds. It covers the time from lift-off -7s till well after engine shutdown. With this I wanted to compare the real altitude and pitch attitude callouts with my manually flown profile. I just wanted to share that I was able to match the original/historical climb rates by doing it like described above very closely. I was hoping, whenever RMaia returns, he will have a look and try to change his code, as to me it seems that the pitchover of the ascent stage is happening way too slow and too late by the current autopilot. By the time it reaches -54 pitchdown you find yourself rocketing up at several hundred m/s...
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My Project Apollo work in progress:
* New detailed Lunar Module Ascent stage with virtual cockpit (VC currently planned as eye candy only) 18 % done

My Project Apollo work to be continued:
* new Service Module SPS engine bell
* various Saturn V textures, exhaust textures
* SIM Bay for the SM


My long-term plans are to create a:
* New detailed Lunar Module descent stage (eventually models of all flown LM's)
* New F-1 engines for the S-1C stage showing the foil (batting) insulation
* New LUT and launch pad (if nobody else does it)
Tschachim
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« Reply #10 on: June 02, 2005, 09:22:28 AM »

Ahh, OK, I understand. I only wanted to mention that the code in CVS is not working properly and I'm not able to fix it.
So I wrote a bug report: http://sourceforge.net/tracker/index.php?func=detail&aid=1213532&group_id=129726&atid=716072
Hopefully RMaia (or someone else) can have a look at it...

Cheers
Tschachim
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LazyD
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« Reply #11 on: July 08, 2005, 02:07:37 PM »

While working on the LM landing programs, I find myself getting interested in abort modes, which happen to be very similar in nature to ascent-to-rendezvous.  

I'm currently in sort of a wait state on the landing code - for the new panels and a leftwindow, so I'd be interested in working on abort/ascent/rendezvous if I wouldn't be butting into someone else's project.

My goal is the ability to hit abort or abort stage at any point in the descent and fly the LM ascent stage to station-keeping with the CSM using the AGC (or even the AGS, if we ever have one).  Ascent from the lunar surface is a bit easier, at least you can choose your timing!

Does anyone know if Rodrigo is still working on the ascent autopilot?  If so, great!  If not, I would be willing to go to work on it.

Please advise,

D.
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Tschachim
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« Reply #12 on: July 08, 2005, 02:56:57 PM »

Quote from: LazyD
Does anyone know if Rodrigo is still working on the ascent autopilot?

Unfortunately I have no clue. Did you mail him already?
If he has no time it would be great if you could work on the ascent autopilot!

Cheers
Tschachim
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