"Well, what's on the computer then?"

"It looks like a Penguin..."

If this works, expect a larger unit for vacuum work, as NASA tries to do everything possible to reduce the number of EVAs required. You would need another propulsion system (likely a compressed-air system), some lead shielding (orbital radiation is likely to mess up your average microprocessor), and something to bleed off waste heat (you have to radiate, rather than just dump heat to the surrounding air).

Lucas' Law: Good will always win, because evil hires the stupid engineers.

/ k.d / earth trickle / Monkeys vs. Robots Films /

Actually, the first movie that came to mind when I read this item was "Phantasm," in which a little floating orb drilled into people's skulls...

--
Think Green... Burn only 100% recycled dinosaurs in you car.

/ k.d / earth trickle / Monkeys vs. Robots Films /

/ k.d / earth trickle / Monkeys vs. Robots Films /

/ k.d / earth trickle / Monkeys vs. Robots Films /

Good is never good enough when you dream of being the best.

Wait till NASA comes out with "knife missiles".. then we're in trouble.
-Andrey

I figure I may as well chime in here. I'm one of the research scientists at NASA working on the PSA (though it's been renamed SMR, Spacecraft MicroRobot, nobody seems to want to call it that). Right now, we have a version that floats on an air hockey table in two dimensions (actually, a fifteen ton granite slab is the table, and the PSA has an air pump so that it floats like a hovercraft), just as a proof of concept and to test control algorithms. We are currently designing the gimbal to test the three dimensional (though larger, since it will still be a prototype) version, which we are also designing right now.

As for a few of the things posted by other people: the speech technology is pretty far along. If you look at the NYT this morning, there is an article about a car computer that accepts speech commands. There are still many issues that we need to work on, but it's not that far off.

The current plan for propulsion are a bank of six fans (not pictured on the model). We have four fans on the 2D version, so 6 will give us enough to move in 3D. Compressed air is a nice idea, but the question becomes how to direct it, how to generate it (assumming that you don't want to have to carry a canister, which is very heavy), and how much force you can actually get from it.

I like the image of a PSA avatar (the dancing paperclip).

We can test it in microgravity in two ways: First, we are building the gimbal that I mentioned above, which allows us to test it in a limited range here in the lab. Second, we will use the "Vomit Comet", the plane that goes into a long dive, providing low-gravity for about thirty seconds at a time.

And yes, the fans spinning up in micro-g cause all kinds of control problems. From where I'm sitting, I can see two people that are using up all of our writing pads trying to solve them.

The air hockey table is a good idea. I'd guessed you were going to have to use the 'Vomit Comet' for testing--you could give that work to the interns.

Not sure if you'll read replies to your AC post (if you get an account there's a link that makes checking for replies much easier), but what kind of processor is used? Is the code written in LISP or C like most embedded code?

Thanks.

Okay, not to throw a light of doubt on this, but I'm not so sure an A/C claiming to work at NASA throwing around some ideas should really be trusted.

1) The fans spinning wouldn't be an issue with a simple fixed-axis gyroscopic system like they use in airplanes for the horizon control.

2) You can't use one of those with six fans, that's the biggest proof that this guy doesn't know what he's talking about.

I also can't imagine that carrying compressed air really would be an issue.

Confucius say: Is better to be silent and be thought a fool, than to speak and remove all doubt. I believe the AC; I can't take you seriously.

One thing you may want to add to your list of things you hate: accusing someone of igorance with a criticism that demonstrates far more ignorance than the comment you are critisizing.

Aircraft attitude-control systems use aerodynamic forces, not gyroscopic, to aim the nose in the desired direction. The gyros are for reference, not reaction.

No kidding? Really? Damn, no wonder I had to push on those pedel things and turn that wheel last time I was flying a plane. I was confused for a moment. Betcha I was talking about the artificial horizon. Ooops. Probably should've spelled that out. My bad.

Incidentally, I hope you don't forget to pull power next time you do a spin to the left. If the engine is cranked up to speed the gyro effect of the prop can hold the nose up and put you into a flat spin, and judging from your comments above I don't know if you'd be able to reliably recover from the normal situation.

Here's an experiment for you kids at home: Take the wheel off your bike. Hold on to both sides of the axle, and get someone to spin it for you. Try to rotate it. Every first grader has done that in science class (except in Kansas where the wheel doesn't exist because the Bible has the value of Pi wrong, and Man never evolved to calculate it better...). You most certainly can stabilize an object from rotational forced using three gyrosopes aligned to each axis.

Oh, and they're frequently used in missile guidance systems for stabilization, not just referance.

'Fraid he's right and you're not. You have exactly three perpendicular axes, so three thrust lines will do. To balance torque around each one, you have two fans per axis. Each fan pair can pull as well as push, so you do not need two fans per face. Three axes * 2 fans/axis = 6 fans.

'Fraid you're doing the same thing he did, assuming you've got to be able to control movement in three axis when maneuvering in 3-D. Obviously you've never tried it. I haven't in zero-g, obviously, but I have underwater. You need to be able to move along X, Y, and Z, plus rotate around those axis (yaw, pitch, roll). Otherwise you can't turn around. And notice in the diagrams there's a camera. Sucks if something interesting is happening behind it and it can't turn around.

Just a hint: you're not symmetrically buoyant in the water. Your legs are a lot heavier than your lungs, giving you a head-up bias. You can't generalize from what you experience paddling around with your hands to zero-G.

You don't need two fans per face, that's true. But unless you have them equidistant from the center of gravity, you have stability and control issues. If you have them inline, spinning in opposite directions (one fan blade has its blades inverted), then you can cancel it out. But with only six, you need to vent the air for the opposite site through the device, with as little resistance as you get on the powered side.

Tough to get right, but doable. Not much room for electronics in a sphere like that after you do, however. Six just can't do it. Hell, four can't do it in 2-D, because you still have X, Y, and orientation (three axis instead of six).

Look up Froude efficiency, and compare that of an air jet to a fan 4 cm across. Then compute the energy capacity of a volume of compressed air at 1000 PSI, and the same volume of NiMH battery. How long can each deliver 0.01 Newton of thrust? Show your work.

You're operating in a nearly frictionless environment. Efficiency isn't an issue. You need accuracy in thrust. Releasing compressed gas through an accurate valve is a lot more precise than issues with varying efficiency of a fan at different speeds, and compensating for spin-up time. But that's neither here nor there. Six gas jets, six fans, either way its simply not going to work.

1. You're not in a frictionless environment; cabin fans produce air currents, which will continuously drag anything in their path with them. Holding position against air currents is part of the job, and it requires more or less continuous thrust.
2. Efficiency is an issue for speed of motion (how many accelerate/stop cycles to .5 m/sec can you do before you run out of juice?) as well as operating time between recharges.
3. You've not explained why an air jet is more precisely controllable than a fan coupled to an electric motor. The air jet is either on or off; the motor is potentially controllable from zero to max RPM in infinitesimal steps.

Maybe you oughta stop reading the fortune cookies, and think more about your posts.

:)

"There is no surer way to ruin a good discussion than to contaminate it with the facts."
-- Cecil Adams

http://www.whidbey.com/forward/

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Remove the obvious in my sig to e-mail me.

That that is is that that is not is not.

It wasn't an update you ninny!

Let's start with the Slashdot title, "NASA show off new 'Star Wars' type PDA". Which part of new don't you understand?

Second, what would the update have been (assuming the duplication was intentional)? Both articles estimate the devices will be ready in a couple of years. The space.com article mentions, "The systems on the PSA just passed an initial test...". Would that ground-breaking news make it worthy of an additional Slashdot feature?

There seems to have been some progression by the engineers since the first article (which I missed), so I would class it as an update. And new can refer to something that already exists. As in here's the first version of the doodad, and here's the new version.

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