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Re: Space Shuttle - Development

Postby eatdirt » Tue May 04, 2021 9:05 pm

Yes, it probably wouldn't hurt to check thoes positions. I don't know who originated them.


At last, this part is done, old school :D

Image


I have everything needed to start tuning the RMS animations and computations. I have a question though. I would like to introduce the shoulder origin coordinates as "static" in the code, they are used a bit everywhere but never modified. Is this fine if I set some nasal variables for this? Under the SpaceShuttle module? thanks!

Cheers,
Chris.
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Re: Space Shuttle - Development

Postby wlbragg » Wed May 05, 2021 2:50 am

Sure, I don't see why not. Unless I am not understanding your question.
I'm excited to see this get worked on.
I have plenty of other stuff to work on, but this whole "targeting" issue is at the heart of some other stuff in the works for the HST.
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Re: Space Shuttle - Development

Postby GinGin » Fri May 07, 2021 5:05 pm

I was wondering if it would be feasible to implement the Outer Glide Slope PAPI, calibrated at 20 °
It would be placed at TAEM Aim Point stored during TAEM initial computation
Code: Select all
var TAEM_AP = geo.Coord.new();


It looks like that

Image

Image
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Re: Space Shuttle - Development

Postby eatdirt » Sat May 08, 2021 2:05 pm

I'm excited to see this get worked on.
I have plenty of other stuff to work on, but this whole "targeting" issue is at the heart of some other stuff in the works for the HST.


All right. I've tuned the coordinates and now making some tests.

Good news, all slight mismatches between end-effector and payload are gone, the end effector remains always perfectly centred and tangent on the grapple target once attached in all directions.

Bad news: I've found a subtle bug which needs to be fixed before Wayne can add any 3D frames on the end effector. We have forgotten a roll. What I mean is that even if you don't order a roll motion on the end effector, there is a roll induced by the motion of all the other parts of the arm onto the end effector. Look at your own arm, put and freeze your fingers perpendicular inside, and move your arm up and down with frozen elbow attitude. Your fingers roll, and we don't have that coded.
The interesting part is that this is completely invisible if you use the manual augmented mode, because all motions in this mode are at fixed attitude. But if you use the "Single" joint mode, and start changing pitch with the wrist yaw large, like 70 to 90 degrees, the payload does not roll whereas it should. I've spotted this because the camera calculations are also missing this part, and even though it remains fixed w.r.t the payload, we clearly see the 3D model of the end effector rotating. And, Wayne, since you add a 3D frame onto the 3D end effector, I need to fix this for the camera. But if I fix this for the camera, I need also to fix it for the RMS. So, still quite some work to do!
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Re: Space Shuttle - Development

Postby GinGin » Sat May 08, 2021 9:43 pm

The work on the RMS looks promising. Thanks for that.
Good luck with all that trigonometry:)

I pushed a FDM change commit.
It does impact the Basic Cl and Cd using more recent wind data tunnels for Mach below 3.
Also the Ground Effect is now deeper modelized with tables that take into account Lift and Drag generated by the ground effect as a function of Height, Elevon deflections and Angle of Attack.
Let me know how you find the slightly different TAEM experience (especially the final flare) and if there are any discrepancies .
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Re: Space Shuttle - Development

Postby Thorsten » Sun May 09, 2021 5:23 am

I was wondering if it would be feasible to implement the Outer Glide Slope PAPI, calibrated at 20 °
It would be placed at TAEM Aim Point stored during TAEM initial computation


I guess... it could be a Shuttle-side placed model like the launchpad driven from the Shuttle navigation code. Someone would just have to do it.
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Re: Space Shuttle - Development

Postby wlbragg » Sun May 09, 2021 3:08 pm

Ah, I didn't understand that question completely. Now I think I get it. You want the model of the PAPI to be placed at any landing site dependant on what TAEM is computed for the mission at hand.

I can help you with that GinGin. I need an image and scale. Then eventually a bit of guidence on what code or property wold hold the TAEM information needed to place the model.
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Re: Space Shuttle - Development

Postby GinGin » Sun May 09, 2021 6:48 pm

I can help you with that


Thanks Wayne :)
It is indeed a PAPI located in the runway axis , 6500 or 7500 feet before runway threshold calibrated at 20 degrees.

TEAM code for triggering it would be the availability of TAEM guidance:
Code: Select all
if (SpaceShuttle.TAEM_guidance_available == 1)   


The location would be the Outer Glide Slope aim point geo coordinates:
Code: Select all
SpaceShuttle.TAEM_AP 


The chosen runway final axis:
Code: Select all
SpaceShuttle.TAEM_threshold.heading 




For the PAPI informations, I got the following pictures .

Image

Image

Image



I will try to find a hd real picture. The only one I found are in the above posts.
Last edited by GinGin on Mon May 10, 2021 5:08 am, edited 1 time in total.
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Re: Space Shuttle - Development

Postby wkitty42 » Sun May 09, 2021 8:25 pm

GinGin wrote in Sun May 09, 2021 6:48 pm:
Code: Select all
if (SpaceShuttle. TAEM_guidance_available == 1)   

Code: Select all
SpaceShuttle. TAEM_AP 

Code: Select all
SpaceShuttle. TAEM_threshold.heading 


why do you have a space between the dot after "SpaceShuttle" and "TAEM_blah"? doesn't that break something?
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Space Shuttle - Development

Postby GinGin » Mon May 10, 2021 5:09 am

wkitty42 wrote in Sun May 09, 2021 8:25 pm:why do you have a space between the dot after "SpaceShuttle" and "TAEM_blah"? doesn't that break something?


An IPad Copy/Paste typo mistake :)
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Re: Space Shuttle - Development

Postby eatdirt » Mon May 10, 2021 7:39 am

In the process of tuning the rms Arm, I have to adjust the origin of all the ac3d files. I am taking the opportunity to rescale the grapple fixture, I think ours are too small and they slightly differ in size between the HST and Spartan, which will break the camera tuning.
So I'll make them of all the same size, with a diameter of 22.5 inches, based on -->

Image

Let me know if you have other info about the grapple fixture dimensions, especially if they do not match these! Thanks.

Cheers,
Chris.
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Re: Space Shuttle - Development

Postby Johan G » Mon May 10, 2021 9:30 am

eatdirt wrote in Mon May 10, 2021 7:39 am:Let me know if you have other info about the grapple fixture dimensions, especially if they do not match these! Thanks.

Challenge accepted! :D

There are some heights on a drawing in the middle of Shuttle Robot Arm, September 28, 2000, Japanese Space Agency (JAXA)

A dimensional side view of the FRGF can be found in on page 114 of International Space Station Program - Mobile Servicing System (MSS) to User (Generic) - Interface Control Document, Part I (457 kB PDF file), Revision E, May 22, 1997, NASA/Canadian Space Agency (CSA).

While not having dimensions and strictly being the Free Flyer Grapple Fixture (FFGF) rather than the Flight-Releasable Grapple Fixture (FRGF) it is based on, there is a crisp top view at page 47, and a crisp side view at page 102 of International Space Station Program - International External Robotic Interoperability Standards (IERIS) (3,7 MB PDF file), Draft C – February 2018, the International Space Station (ISS) membership.

I think I also have seen another side view with dimensions somewhere. Try an Google image search for "flight releasable grappling fixture dimensions".
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Re: Space Shuttle - Development

Postby eatdirt » Mon May 10, 2021 9:53 am

Woo, great, thanks Johan. Perfect, that is matching, 22.5 inches.
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Re: Space Shuttle - Development

Postby Johan G » Mon May 10, 2021 12:16 pm

You are welcome. :D
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Re: Space Shuttle - Development

Postby eatdirt » Thu May 13, 2021 2:47 pm

Oh god, I've spent the day to fix the normals on Spartan... I understand your pain Wayne... It's beautiful and shiny now, with a white grapple fixture matching this one:

Image

Still one to go, once TDRS got its fixture, I'll push a merge request!
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