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ISS Docking Simulation

iss-sim.spacex.com

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Re: ISS Docking Simulation

#121

Post by effie »

elteto wrote: post #79
JshWright wrote: post #41

Earlier quoted context omitted.

In some ways... In many other ways the physics was wildly inaccurate.

The rope scene always bothers me. Why are the ropes and the strap taut after the first snap? What’s pushing him away? It sure isn’t wind! And there is no rotation either. [0] https://youtu.be/DYDaIyfitn8

In the frame of the orbiting station, there is the tidal force, which is proportion to distance from the point where the rope is fixed on the station. But even if he was 100m away, tidal force would be like 7 grams.

So tidal force can't be it. The most likely reason would be some part of the station venting gas out, accelerating. The gas could blow towards the astronaut to make it worse.

Re: ISS Docking Simulation

#122

Post by JshWright »

effie wrote: post #121
elteto wrote: post #79

Earlier quoted context omitted.

The rope scene always bothers me. Why are the ropes and the strap taut after the first snap? What’s pushing him away? It sure isn’t wind! And there is no rotation either. [0] https://youtu.be/DYDaIyfitn8

In the frame of the orbiting station, there is the tidal force, which is proportion to distance from the point where the rope is fixed on the station. But even if he was 100m away, tidal force would be like 7 grams. So tidal force can't be it. The most likely reason would be some part of the station venting gas out, accelerating. The gas could blow towards the astronaut to make it worse.

Given how fast and loose the movie played with physics in general (orbital mechanics, especially), I wouldn't go too far out of my way to try to explain gaps.

Re: ISS Docking Simulation

#123

Post by [deleted] »

gene-h wrote: post #15

It is quite difficult to control with the mouse. It's basically impossible to kill rotation or velocity along a given axis. So one ends up with bang-bang control, constantly oscillating around the target. I am also somewhat horrified to learn that manual flight might be like this to, through the touchscreen[0]. Although there do appear to be some joysticks the astronauts can use, so hopefully this is just training fo…

[deleted]

Re: ISS Docking Simulation

#124

Post by tgsovlerkhgsel »

_archon_ wrote: post #49
amelius wrote: post #38

Is this the way it is done in real life? Wouldn't it be better to let a computer handle this?

I was thinking that the ends of the masts would be excellent places for a machine vision high-contrast target, and maybe also the bottom of the cupola for full 6 axis machine correction. I doubt we'll be taking a human out of the loop anytime soon, though.

It's a really simple task (so humans getting it wrong isn't a major concern), the crew needs to be on board, trained, and equipped with manual controls anyways (for contingencies), so... why spend effort automating it?

Re: ISS Docking Simulation

#126

Post by TeMPOraL »

fctorial wrote: post #114
doctor_eval wrote: post #37

Nailed it first time!! I was super excited too, cos it was so obvious that this so-called “simulation” was in reality a test to find pilots to save the ISS from some top secret calamity that we don’t know about. Surely this was going to be like in “the last Starfighter”, except that Elon Musk would be the one knocking on my door, needing a new pilot. Sadly it just said “congratulations” :(

Nice, took me 3 tries. Although I believe the real thing will be quite different. There will be coupling betweeen various controls. I think it's one of the goals to reduce that by centering thrusters around centres of mass, but there's a lot of moving pieces (humans) inside, and the fuel mass is always changing.

Yup. That's the kind of fun you can experience in Kerbal Space Program. If you just want to fly around teakettle, then you can get away with clever design that ensures the center of mass doesn't shift as you expend RCS fuel. But as soon as you're trying to do anything interesting - e.g. build a lander, or a craft that hauls other crafts around your station - you'll experience coupled controls in full.

I for one love building space stations in KSP, and I tend to have a compliment of "worker bees" - small RCS-only crafts meant to haul big pieces of space stations to their correct positions. So I often attach sideways to a fuel tank that's 2/3 empty and still weighs 10x as much as the worker bee. Docking that thing is an exercise in patience.

Re: ISS Docking Simulation

#127

Post by TeMPOraL »

motoboi wrote: post #113
fctorial wrote: post #67

Open this in new tab. https://www.youtube.com/watch?v=m3zvVGJrTP8

This simulator would be so much better with this music!

For maximum Interstellar experience, type this in the console after the simulator loads:

  (function() {
    var clock = new THREE.Clock();
    var interstellar = function() {
      issObject.translateOnAxis(new THREE.Vector3(0, 0, 1), -20);
      issObject.rotateY(-7.12094334814*clock.getDelta());
      issObject.translateOnAxis(new THREE.Vector3(0, 0, 1), 20);
      requestAnimationFrame(interstellar);
    }
    interstellar();
  })()
(7.12094334814 is "68 RPM", if my math is correct.)

EDIT: Corrected rotation to spin around (roughly) the center of mass.

Re: ISS Docking Simulation

#128

Post by TeMPOraL »

elil17 wrote: post #18

I’m glad this is available online. This is a very standard docking UI for spacecraft - everyone in the industry has an almost identical design. ULA has shown a simulator exactly like this in conferences for years now.

That's... underwhelming. I have a much better interface in Kerbal Space Program, and that's playing IVA (from in-cabin perspective).

In particular, see Docking Port Alignment Indicator mod:

https://youtu.be/zaqCmnUfdzI?t=32

In KSP, I can dock blindly, looking only that little window labeled "DOCK ALIGN" alone. As you watch the video, note how it displays both velocity vectors, as well as component-wise relative speed difference (left/right and top/down with green lines, forward/backward as a number) and all 3 rotation axis on screen at the same time.

Re: ISS Docking Simulation

#129

Post by TeMPOraL »

Cerium wrote: post #106
tyho wrote: post #47

Rotate, Translate, Approach. By the numbers, ignore the graphics.

Once rotate is dead on and stable, translate and approach can be helped by the graphics.

Only if you're very close. Trust the Kerbal greybeard (greenbeard?) me, visuals are misleading you about relative velocities.
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