[simpits-tech] Motion...
Erwin Neyt
simpits-tech@simpits.org
Wed, 2 Apr 2003 13:38:54 +0200
Chris is right,
motion-simulation = 90% visual + 10% real-motion.
One very important requirement for the visual system: peripheral coverage,
so at least 120 degrees, more is better.
Erwin.
> -----Original Message-----
> From: Chris Brace [mailto:chris.brace@paradise.net.nz]
> Sent: woensdag 2 april 2003 12:04
> To: simpits-tech@simpits.org
> Subject: RE: [simpits-tech] Motion...
>
>
> If your really keen here is another link for you.
> http://www.cadsoft.de/~kls/fltsim/
>
> This project is very cool and uses some ingenious ideas. Cost
> is bugger all, but sadly there has been little movement (pun
> intended) on it for a while now.
> I'd love to put one of these under my F16-something or other
> but in all honestly good visuals and simple motion queueing
> would be a lot simpler and just as effective.
>
> I did a couple of hours flying in a full military sim a few
> years back. It was an AirMacchi MB339, using a 3 screen
> colminated display with a fixed (no motion) base. The
> feedback from the controls, the sounds system and the visuals
> were enough to fool me. I actualy got vertigo during a pop-up
> from ground level to 5000ft and rounding off the top. I
> suddenly had to grab for the canopy bow because I felt like I
> was about to fall over the top as I rounded out and pointed
> down to the ground again. It was a very good lesson about
> visual being able to fool the senses.
>
> Chris.
>
> -----Original Message-----
> From: simpits-tech-admin@simpits.org
> [mailto:simpits-tech-admin@simpits.org] On Behalf Of Gordan Sikic
> Sent: Monday, 20 January 2003 10:17 p.m.
> To: simpits-tech@simpits.org
> Subject: Re: [simpits-tech] Motion...
>
>
> Hi,
>
> Joseph Fagner wrote:
>
> >Think about this for a minute (granted I realize this is probably
> >overly simplistic and the math is infinitely more complex): Most
> >software out there has the 4 axis of data (not to be
> confused with the
> >axis of evil) one might need for motion. Couldn't one just
> write some
> >software to read this data and translate that to motion?
> The data to
> >which I refer is (1) pitch and (2) roll (X and Y axis); via your
> >artificial horizon instrument. (3) Yaw (Z axis), via your
> compass and
> >(4) altitude via the altimeter.
> >
> >
>
> It is not that simple.
>
> You need angular rates as well as accelerations. Making
> motion platform
> based on attitude of the AC would be waste, beleive me. Generally
> speaking, with the motion platform one hopes to imitate (inertial)
> accelerations that pilot feels. Simple example acceleration on the
> runway during take-off. During that period pilot feels sustained
> acceleration on his back. The sense of acceleration is imitated by
> rotating the platform slightly backwards, so the weight of
> the "pilot"
> generates the force on the back. That shift is sudden, and later the
> platform is slowly returned to middle position. Thus,
> imitation of just
> one linear acceleration is achieved completly different type
> of motion
> (sudden rotation, followed by slow return to neutral position).
>
> Other than this, you should think of something completly
> different: Motion platfors are _very_ power hungry, you might
> easilly end up with
> facility which draws couple of tens of KW of power.
> Yet another problem is safety. Think of the following: it is
> very easy
> to start the filre in the chitchen with electrical oven of
> just couple
> KW (or even less), and here you are dealing with much more powerfull
> equpment.
>
> Yet yet additional problem are foundations, because something must
> support complete construction, and take over complete forces
> and moments
>
> generated by themoving platform.
>
> There are many problems, but this doesn't mean that there is
> no sollution :) If you really want to make motion platform,
> do read apropriate chapter
> in "flight simulation", book that is mentioned few days before. It is
> excelent reading, but be warned that it does not provide us with
> sollutions, but presents the problems in very concise way, and just
> guides towards the solution. But in any way it is a "must have" book.
> I've been reading it from the cover to cover and all over again many
> times :)
>
> Also check web for motion platforms where you will find some
> standards
> you should achieve. one url is www.fokercntroll.com, and the
> other is
> (if I recall correctly, I'm off line now) www.mug.com.
>
> Personally I'll take following approach:
> Generaly, visual system provides low frequency sensations, and use
> motion (vibrations to be specific) for the high frequency sensations
> (like tyrbulence, or vibrations, ...). This is not as good as
> well made
> motion system coupled with nice visualisation, but it is
> _much_ better
> than wrongly made motion platform, and in any case infintelly safer.
>
> At the end one true story:
> (I don't know the details, what kind of AC, how many degrees
> of freedom
>
> in motion platform, nor how many pilots, ... :)
> There was a project of evaluating different algorithms for driving
> motion platform, and within the project many (profesional)
> pilots were
> flying on the simulatior, every flight with different
> algorithm applied.
>
> Needles to say that pilots didn't know which algorithm was to
> be applied
>
> for any of the flights. After every try, they were asked to
> describe in
> words how they felt, and to place a numerical mark. After the
> data were
> analysed, it turned out that many pilots (more than few, anyway) said
> that the best results were achieved with algorithm "number
> 5". The funny
>
> thing was that algorithm in question corresponded to the case
> where the
> motion platform didn'mtmove at all! Of course, pilots didn;t
> know that
> fact while "flying"
>
> >Jay
> >
> >-----Original Message-----
> >From: simpits-tech-admin@simpits.org
> >[mailto:simpits-tech-admin@simpits.org] On Behalf Of Roy Coates
> >Sent: Friday, January 17, 2003 6:57 PM
> >To: simpits-tech@simpits.org
> >Subject: Re: [simpits-tech] Motion...
> >
> >On Fri, 17 Jan 2003, Brian West. wrote:
> >
> >
> >
> >> I have an excellent book published a few years
> back. The title
> >>
> >>
> >is "
> >
> >
> >>Flight Simulation" by J.M.Rolfe and K.J. Staples, published by
> >>
> >>
> >Cambridge
> >
> >
> >>University Press, ISBN 0-521-35751-9
> >>It contains all the mathematical models etc needed plus a lot more.
> >>
> >>
> >It's
> >
> >
> >>almost certainly out of print but a search of secondhand
> book dealers
> >>
> >>
> >might
> >
> >
> >>turn up a copy.
> >>If you can't find a copy come back to me . It's all a bit daunting
> >>
> >>
> >though,
> >
> >
> >>time and costwise for an individual.
> >>
> >>
> >
> >Thanks Brian - appreciate that. From what little research
> I've done so
> >far it has become quite clear the there is no fixed rule to motion
> >simulation,
> >there seem to be several schools of thought on the topic.
> >
> >It also seems clear that each method has its own weaknesses. I'll
> >continue searching!
> >
> >Roy.
> >
> >
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> >
> >
> >
> >
>
>
>
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