Author Topic: CEV abort system gains a brain  (Read 16749 times)


Offline David AF

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RE: CEV abort system gains a brain
« Reply #1 on: 12/20/2005 09:40 PM »
How cool is this! This CEV is sounding better by the day. The new computers are going to be amazing by the read of info like this and I don't think anyone would be happy about another new vehicle without an escape.
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Offline Space101

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RE: CEV abort system gains a brain
« Reply #2 on: 12/20/2005 10:07 PM »
Sounds very interesting. Will it override human reaction? Suppose it would have to with the speed of a possible failure, just like Challenger, even if Challenger had no means to eject the crew out of the way.
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Offline Chris Bergin

RE: CEV abort system gains a brain
« Reply #3 on: 12/20/2005 10:40 PM »
I think the system has to over-ride humans in an emergancy. It may also be the first alert of the astronauts and controllers.

I'm not sure how this would work. I would hope there would be some warning, as in such a situation, they are going to be fired out and away of the booster at X amount of G. I'd want to know about it!

I want to interview the people involved, so there's more to come I'm sure. I'll ask if they are open to it and see about setting up a  and A on the forum.

Offline STS Tony

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RE: CEV abort system gains a brain
« Reply #4 on: 12/21/2005 12:37 AM »
And if the first stage or second stage blows up, the Escape System can get the module out of the way fast enough? I don't see how it's much use apart from saving the need for a RTLS abort? Someone who knows these things better than me might know better.

Offline To The Stars

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RE: CEV abort system gains a brain
« Reply #5 on: 12/21/2005 12:59 AM »
Fantastic. Not only is the crew escape totally required to be back in NASA man-rated vehicles, I'm so encouraged such an established bastian of computer software intergration technology such as Texas Tech is involved in the programming of the new vehicle. This is superb news and thanks for bringing it to our attention!

Offline Jamie Young

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RE: CEV abort system gains a brain
« Reply #6 on: 12/21/2005 03:50 AM »
Damn, nearly missed this! A new system and even a new programming language, is this what they did with the Shuttles when they were first made?

Offline realtime

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RE: CEV abort system gains a brain
« Reply #7 on: 12/21/2005 05:02 AM »
Neither of the languages mentioned in the article are proven "real-time" languages, which means roughly, that if a program is written to perform task A in time T, and it can only perform the task in time T+n, then the program is broken.  Real-time languages support such tight scheduling deadlines.  They are commonly used to code flight control systems, data acquisition systems, medical systems, etc.

SequenceL is an experimental data-abstraction language which is another way of saying it's designed to "free the problem solver from much of the difficult effort required to produce algorithms that imply the data products they desire" (1).  Oof.  This language has never been used anywhere outside academia to my knowledge.  It supposedly does have a real time variant, but again, I can find no evidence of it having been used in any high-reliability industrial application.

A-Prolog (2) I cannot even find a reference to.  Prolog (plain old variety) has been kicking around for many years but never really caught on in industry.  It's used in some expert systems and database applications and as a batch database correlator for some real-time front-ends.

As far as I can tell, nobody writes in SequenceL except the guy who designed it and his grad students at UTexas.  Lots of people putz around with Prolog, but it's really used to generate masters' theses and hobby projects.

Maybe I'm too old-school, but this doesn't strike me as good news.  It sounds like somebody in NASA saw a "shiny object" and made a decision based on the glitz and glamor of these "natural language" tools.  The system they have presented here is, in my opinion, overblown.  It is based on specious theory and an untried language that, if carried to completion, will have as its first implementation our CEV abort system.

Personally, I would feel lots better if the abort system was a small program running on VxWorks and written in C by a few hard-core real-time programmers, but that's just me.  I like stuff that works.

(1) http://64.233.161.104/search?q=cache:cQP8Rz6oJycJ:www.cs.utep.edu/vladik/2002/tr02-24.doc+sequencel+language&hl=en

(2) http://kti.ms.mff.cuni.cz/~bartak/prolog.old/FAQs.html


Offline Jamie Young

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RE: CEV abort system gains a brain
« Reply #8 on: 12/21/2005 05:07 AM »
You sound like you know what you're talking about. What do you think would be a better choice of software/lanuage, whatever this is? ;) I know nothing about this subject.

Offline Dobbins

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RE: CEV abort system gains a brain
« Reply #9 on: 12/21/2005 05:50 AM »
Quote
Jamie Young - 21/12/2005  1:07 AM

You sound like you know what you're talking about. What do you think would be a better choice of software/lanuage, whatever this is? ;) I know nothing about this subject.

HAL/S, the language that was developed for the Shuttle computers. It's a real time language that has been throughly debugged over the past 30 years.

Most computer programs are written in a high order language that is easy for humans to understand, but these have to be translated into assembly language that the computer can understand by a compiler. If there is a bug in the language, then there will be bugs in the program that is written with it.

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Offline lmike

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RE: CEV abort system gains a brain
« Reply #10 on: 12/21/2005 09:24 AM »
Sounds like they are just prototyping in this new language.  For this sort of hard real-time reqs. I'd go with an FPGA circuit or even a custom build ASIC chip.  Directly wired to the sensors and the manual abort switch and the LES motors/CEV separation bolts.  Needs to be close to the metal.  As simple in logic as possible.  'Primitive', even.  Especially with a solid as the first stage.  Must not have an (computer) override if the crew/ground controllers elect to abort (due to visual clues for example)  But an override to force an abort above certain threshold of malfunction data.

Offline FransonUK

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RE: CEV abort system gains a brain
« Reply #11 on: 12/21/2005 11:17 AM »
So do we think the CEV will ever be in a situation that force an abort without prior warning to the controllers or crew? I obviously like the idea of the commander or controller having the final say, but given the human brain will not react as fast, that could make the human control pointless in an emergancy?

Note Challenger.
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Offline Rocket Ronnie

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RE: CEV abort system gains a brain
« Reply #12 on: 12/21/2005 11:54 AM »
Never take the control to abort away from the pilot or commander is what I'm thinking. I'd feel a bit wrong if I was flying in something that was in control of saving my life.

Offline Chris Bergin

RE: CEV abort system gains a brain
« Reply #13 on: 12/21/2005 11:58 AM »
But what point is that if it's a Challenger situation, where the only member of the crew to notice managed to utter "uh oh" before break up. Even if he had aborted on the uttering those words, it'd of been too late. Yet Challenger was already going through processes to try and correct the problems, before that was made pointless by the SRB twisting into the ET.

I know what you mean as far as control with the Commander, and I agree - but how do you get around the problem of not being able to react as fast as the computer?

Offline Martin FL

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RE: CEV abort system gains a brain
« Reply #14 on: 12/21/2005 12:13 PM »
It's a fine line they have to find. This system is going to be used to at least work out what needs to be done once the Abort is in progress, whether it will decide if to actually Abort is the interesting element.

Offline SimonShuttle

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RE: CEV abort system gains a brain
« Reply #15 on: 12/21/2005 01:07 PM »
How do other abort systems work, like on the older US versions, Apollo etc. And maybe on the Russian ones?

Offline Dobbins

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RE: CEV abort system gains a brain
« Reply #16 on: 12/21/2005 05:12 PM »
Quote
Chris Bergin - 21/12/2005  7:58 AM

But what point is that if it's a Challenger situation, where the only member of the crew to notice managed to utter "uh oh" before break up. Even if he had aborted on the uttering those words, it'd of been too late. Yet Challenger was already going through processes to try and correct the problems, before that was made pointless by the SRB twisting into the ET.

I know what you mean as far as control with the Commander, and I agree - but how do you get around the problem of not being able to react as fast as the computer?

In Apollo the system would do an automatic abort under certain conditions, or the comander could do a manual abort.

http://en.wikipedia.org/wiki/Apollo_spacecraft#Launch_Escape_System_.28LES.29

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Offline lmike

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RE: CEV abort system gains a brain
« Reply #17 on: 12/22/2005 12:14 AM »
Of course, the system should be able to do an auto abort, the whole point of the electronics on the LES is the fast reaction time, especially with solids there are less things to monitor for clues.  Or, if the crew are incapacitated.  The manual control is there just to force an escape, not to prevent it.  I'd also give this ability to the ground controllers, in case there are some visual clues from outside on launch.  There could be (extremely unlikely) scenarios where the system could do a false abort in the extremely short time that the LES is active at all, 2 minutes of the ascent?, but at the worst the crew would survive, just with a loss of a good vehicle.  

So, the rules in my view: if the electronics and/or the crew decide to abort they abort.  Whoever throws the switch first.  If the system doesn't think it's time to abort, but the crew do, they still abort, the electronics stand aside.  The other way scenario is not likely since the reaction time of the system would be much faster than people flipping the override switch to stop it, but I'd say if the crew disagree, the system still aborts.  

The bigger problem, I think, is how to make a reliable abort decision based on a few sensor readings.  But with some statistics of what can go wrong with a solid first stage most of which has already flown some 200 times, and a couple of sensors here and there it's not that hard really.  Nothing that requires an AI, or a high level language, that's for sure.

Offline lmike

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RE: CEV abort system gains a brain
« Reply #18 on: 12/22/2005 02:30 AM »
Another thing that I'm curious about is that with the solid first stage, some failure modes (e.g. bad assymetrical grain) the LES motors would have to have much more thrust, or the separation of the CEV done a little sideways, because (in some of the modes) the abort system couldn't attempt to throttle down the first stage or just shut off the propellant lines as it could with the liquid first stage, and with a much lighter payload the CLV is going to shoot up like nobody's business and catch up with the CEV/LES stack, although they could blow a hole in the CLV's side with a pyro (hopefully without explosion) to make it lose thrust.

Offline Dobbins

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RE: CEV abort system gains a brain
« Reply #19 on: 12/22/2005 02:36 AM »
The use of a solid booster first stage makes the LES harder to design and program. In the Mercury and Apollo systems the LES could shut down the booster if it was out of control. A solid rocket can't be shut down so the LES has to be capable of reacting to any failure modes that produce side thrust.

The Mercury LES didn't even use a computer, it's sequencer relied on relays and logic circuits. You could get by with something that simple on a liquid fueled rocket, though it was a nightmare to checkout. A LES for a solid will require a fairly complex program.

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