Register Blogs Orbinauts List Social Groups FAQ Projects Mark Forums Read

1. Playing with simple autopilots

My experience with OBSP autopilots always run me in the same direction: If you can calculate a variable exactly instead of relying on control algorithms... DO SO!

If you take killrot for example... you should be able to calculate with a very high precision how long each thruster needs to fire at full power to bring the angular velocity down to 0. With things like rigid body physics, this works VERY well.

You still have to get rid of the jerkiness at close to 0 though.

This kind of system works well even when you can only come up with a rough estimate for the problem - where it's impossible to calculate because you simply don't know some variables or because math won't allow it.

For my atmospheric autopilots, I calculate when a plane should return the aileron from full deflection to no deflection so that when the aileron gets there exactly at the moment when the plane hits the target roll and no angular velocity.

This doesn't work exactly. Just too many variables that I can't predict. Some because of limitations of Orbiter, some because I treat them as constants when they're not,...

If you look closely, you'll see that the air control surfaces shake, but the shaking is small enough so that the plane itself doesn't shake.

When you're working on something as specific as your autopilot, you can go ahead and choose a particular control algorithm and tweak it. But the moment you apply it to a different craft, it'll misbehave, so setting desired angular velocity and angular acceleration can come back and bite you in the ass...

For practice, you can try writing a "fast horizon level" autopilot. The idea would be to fire the RCS at full power and let the angular velocity increase. Calculate when the RCS should be reversed in order for the lander to have 0 angular velocity just as it reaches horizon level...
Posted 04-10-2013 at 11:23 PM by RisingFury
2. 3D Moon landing sim

That sounds pretty complicated - it might be possible, if I can't find some heightmaps, to just create the main features manually using pictures.
Posted 03-29-2013 at 09:56 PM by george7378
3. 3D Moon landing sim

I can generate them from altitude curves, but it would take time. Nevertheless, I'll do research and see what I can find regarding actual data.
Posted 03-28-2013 at 10:23 PM by 4throck
4. 3D Moon landing sim

Oh, so you mean you'd create the meshes by hand? That would be really helpful, but it sounds complicated! It would be a lot easier if there was a way to get heightmaps for them. Anyway, thanks again. I don't need them right now (I have created some placeholder 3d terrain using a random heightmap I created) so it's ok that you have other things to do!
Posted 03-28-2013 at 05:14 PM by george7378
5. 3D Moon landing sim

I don't have them but I could do them as meshes perhaps.
The only problem is having tons of ongoing projects at the same time :-)

Anyway, for nice terrain check this Apollo 11 landing game: http://www.planetinaction.com/moonlander/#
That's about 10cm terrain precision or less..
Posted 03-28-2013 at 02:11 PM by 4throck
Updated 03-28-2013 at 03:54 PM by 4throck
6. 3D Moon landing sim

Hey 4throck - actually, that would be great! I've been looking for heightmaps for the apollo sites - do you have some? And yeah, I could easily make an LK lander version if I can find a decent model. I'll have a look round!
Posted 03-28-2013 at 12:55 PM by george7378
7. 3D Moon landing sim

Looks cool. If you need textures or panels (2D / 3D) I have some than might be used. Can also help with real terrain ;-) for the Apollo landing sites.
A LK lander version would be great.
Posted 03-27-2013 at 11:02 PM by 4throck
8. 3D Moon landing sim

Haha, well my first game was 'The adventures of the heroic zero and the evil doctor x' - basically, a '0' character moving around in a console window with randomly placed 'x' characters to hit. Sadly it never hit the shelves.
Posted 03-20-2013 at 12:56 PM by george7378
9. 3D Moon landing sim

Late last year. I've dabbled with 2d games (look for my big hit 'Move the red square around the green window'), and a little bit with the Panda3D engine in python, but for the most part I've stuck to CLI programs.
Posted 03-19-2013 at 10:09 PM by mojoey
10. 3D Moon landing sim

This was a lot of messages to wake up to!

mojoey: How long have you been programming? I've been going on and off for a couple of years now, but I've only recently started doing games and 3D stuff (I was too scared to try until now!)

Sam: That's really nice, thanks It would be cool to be a game developer!

codz, Rtyh-12: Thanks - here, progress = lots of trial and error!

Athena - at the moment it can detect collisions fine (there is a 'contact point' at each of the lander's feet - when one of the feet touches the ground, a collision happens). It doesn't have proper rigid body physics though - I need to work out a way to make the lander rotate properly to upright when it touches down, if it lands at an angle.
Posted 03-19-2013 at 11:28 AM by george7378
11. 3D Moon landing sim

Looks nice....just a question, will it have accuracte collision detection?
Posted 03-19-2013 at 08:22 AM by Athena
12. 3D Moon landing sim

Wow, impressive. You have made huge progress, congratulations!
Posted 03-19-2013 at 04:57 AM by Rtyh-12
13. 3D Moon landing sim

Nice!
Posted 03-19-2013 at 02:33 AM by Codz
14. 3D Moon landing sim

Oh nice job man, you're getting wonderful at this stuff. I can see a bright future ahead of you. Good job, George.

Sam
Posted 03-19-2013 at 02:26 AM by Samuel Edwards
15. 3D Moon landing sim

Posted 03-19-2013 at 12:09 AM by APDAF
16. 3D Moon landing sim

Same here, the progress you've made compared to me is just stunning.
Posted 03-19-2013 at 12:04 AM by mojoey
17. 3D Moon landing sim

Thanks Also thanks for the offer APDAF!
Posted 03-18-2013 at 11:47 PM by george7378
18. 3D Moon landing sim

Wow!

Nice stuff!
Posted 03-18-2013 at 11:28 PM by BruceJohnJennerLawso
19. 3D Moon landing sim

If you need a beta-tester just PM.
Posted 03-18-2013 at 11:18 PM by APDAF
20. Attempts at DirectX

Could you post a link to this tutorial? I've been looking for something like this, but I've been completely unable to find any good one.
Posted 01-23-2013 at 01:25 PM by Rtyh-12
Updated 01-23-2013 at 01:25 PM by Rtyh-12 (Typo)

All times are GMT. The time now is 01:57 PM.