[simpits-tech] Motion...

Wed, 2 Apr 2003 18:30:23 -0500

Hi Erwin,

I agree that the visual cues dominate for motion except that G-force cues aren't provided by
graphics in fighter combat.  Of course a motion platform doesn't pull G's either.  The G-suit rig
I'm using does fill this gap.

>From my reading on vision systems and fighter simulators, 60 deg is about the minimum FOV that is
acceptable for military training.  90 degrees delivers good performance.  This is for HMDs where the
wearer can look 360 deg.  Higher FOVs were preferred by pilots, but didn't result in significantly
greater situational awareness or improved task performance.

For a fixed display like a PS, I'd say 120 deg would be very constraining.

Craig

-----Original Message-----
From: simpits-tech-admin@simpits.org
[mailto:simpits-tech-admin@simpits.org]On Behalf Of Erwin Neyt
Sent: Wednesday, April 02, 2003 6:39 AM
To: 'simpits-tech@simpits.org'
Subject: RE: [simpits-tech] Motion...

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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