Motion Platform

[Blake H]

Hi guys,

Will PSX have a pot input for pitch and roll like in FSUIPC for a motion platform. Obviously the output are to the values(hydraulic actuation).

My flight controls will be hydraulic as there is already lines for the control and should give the correct representation.

[Garry Richards]

Will PSX have a pot input for pitch and roll like in FSUIPC for a motion platform. Obviously the output are to the values(hydraulic actuation).

Not sure what you mean by 'pot input'.

PSX will probably provide even more variables for motion platform control than PS1 does already but bear in mind that motion platforms do not replicate the aircraft's pitch and bank angles directly.

The platform's orientation and movement provide, with the help of gravity, accelerations that the pilot experiences. When these are coupled with the pilot's view of the scenery the effect can be quite realistic. For instance, during the takeoff roll the platform will pitch up to simulate the horizontal acceleration while the scenery shows the aircraft still on the runway and not pitching.

Sorry if this is stuff you already know. I'm not sure from your post.  

[Blake H]

Does a motion platform really simulate good lateral and longitudinal g's?

I believe not, that is my option. Like to hear others.

[Mundyas]

Hi Blake

I refer you to a book called Principles of Flight Simulation by David Allerton. (The blurb says - A comprehensive guide to flight simulation design, covering the modelling, algorithms and software which underpin flight simulation.)

Amongst other things the book has a section on Motion Systems. The book was quite expensive though but I would have thought invaluable for you. (For me it was good but more complicated than I really need)

The book mentions page 451 the limitations of motion systems including " In practising  high-altitude or upset recovery , where the aircraft may be subject to accelerations up to 3 or 4G, and large pitch and roll displacements"

Perhaps you could have g-seats! like a military simulator!

Hope this helps a touch.
Andrew

[Jeroen Hoppenbrouwers]

Most practical simulator setups just provide "kicks". They sway and heave to give accelleration onset cues, and then quickly reduce to no accelleration and creep back to where they think they need to be for the next "kick".

PSX by itself does not contain motion platform drivers.

The platform that Matt uses and that Garry programmed came with its own control electronics that do all these "kick" calculations themselves. You feed them plane 6D info and they work out the rest.


Jeroen

[SwissCharles]

Thanks Jeroen for this information.

For these motion cues: Am I right in assuming, that these motion cues do not need to be of a large displacement of the shell?

The reason I ask is that my room isn't that high to allow for these long stroke actuators you commonly see (e.g. Matt's). I would have only about 20 cm (~8") of free travel.

I am thinking of having small but strong actuators in all 4 corners of the sim giving cues for the motion.  Oh and I would have to put the visual system onto the moving platform as well - we don't want to get seasick :shock:
For those who have experience with this, would such a small displacement of the cockpit structure make sense or would its benefit not be worth the hassle?

Thanks for your input and sorry for 'extending' the life of this thread just a wee bit more  

Charles

[the mad hatter]

Blake, In relation to motion I am inclined to think for the expense and the integration issues such as motion cueing wash/roll rates etc that the end result is simply not worth it, much of the immersion can be replicated by butt kickers and decent sound system. Simulation/Immersion is thus really

90% visual
5%   sound
5 %  motion

So in short if you have a decent visual system and the motion is turned off after 3 mins you will not notice.  Then you have to consider hydraulic or electric actuators I think you said you were going to use car jacks! how on earth are you going to get the responses to that lets assume you have three people in your flight-deck plus all the other stuff related to the flight deck that's a fair bit of weight you have move if you thought 40k was a lot of money for a turn key solution as mention in one of your other threads try100K plus for a motion platform.

[Jeroen Hoppenbrouwers]

I totally agree with the mad hatter. I flew many hours in a pro 744 sim without motion (so we could hop out and fetch coffee, hey, it was 03:30 in the night) and it is not needed. The most effect you have during taxi and in turbulence.

I would change your estimates though.
65% visual.
25% sound.
10% motion.

Charles: your idea would probably work fine if you focus on shaking and rattling, and leave most swaying and G-faking completely out. If you cannot tilt 30 deg then it isn't worth it. But those actuators would make for a great bumpy ride and convincing touchdowns.

It would definitely be worth a try to NOT put the visual system on the motion platform. Hefty bumps may become more convincing if the visual does NOT move with them.


Jeroen

[John Davis PC]

I agree with "the Mad hatter" and with Hoppie Blake ... especially as Hoppie was nearly sick in my fixed base sim whilst taxying when I upgraded the visuals from one projector to 3  I also occasionally get customers get queasy and indeed became ill myself after a particularly gruelling 3 hrs session with some Airline Pilots in mine, I was sat behind them so you see more of a picture so to speak.

I also agree with the estimate of cost of motion platform and the fact that in the same way as the question of Aircon, putting 4 bodies in the sim instead of one or two will make a hell of a difference.

Quite a few of the Big sims turn off the motion when training Pilots unless they are doing "upset" training to save wear and tear on the sims.  

I sort of agree with hoppie about not mounting the visuals on the platform however dont think that would work well, Matt spent 6 years designing his Visual system and sought assurances and a 3 year guarantee from the projector manufacturer that they would not be affected by the rock and roll !

[John Davis PC]

P.S. Blake ... if you want to see how it should be done visit this site, you can get an idea of how much it moves by the test videos at the base of the page ... this is Matt's sim , programmed by Garry above

http://www.747simulator.com.au/     click on Design Details and then Motion System

Cheers  PC

[the mad hatter]

I would concur with you gentlemen, that maybe 90% is a tad extreme and that 65 is more in line now add stick shakers, butt kickers and surround sound but Blake if you want a cost competitive entry level D simulator try this for effect

1. Stay out of bed all night.

2. Sit in your most uncomfortable chair, in a closet, for nine or ten hours facing a four foot wide panoramic photo of a flight deck.

3. Have two or three noisy vacuum cleaners on high, out of sight but within hearing distance and operating throughout the night. If a vacuum cleaner fails, do the appropriate restart checklist.

4. Halfway through your nocturnal simulator course, arrange for a bright spotlight to shine directly into your face for two or three hours, simulating flying an eastbound flight into the sunrise.

5. Have bland overcooked food served on a tray midway through the night.

6. Have cold cups of coffee delivered from time to time. Ask your spouse to slam the door frequently.

7. At the time when you must heed nature's call, force yourself to stand outside the bathroom door for at least ten minutes, transferring your weight from leg to leg, easing the discomfort. Don't forget to wear your hat.

8. Leave the closet after the prescribed nine or ten hours, turn on your sprinklers and stand out in the cold and "rain" for twenty minutes, simulating the wait for the crew car.

9. Head for your bedroom, wet and with your suitcase and flight bag. Stand outside the door till your wife gets up and leaves, simulating the wait while the maid makes up the hotel room.

10. When your spouse inquires, "Just what in the **** have you been doing?" just say, "Recalling the allure of all night flying to romantic places." as you collapse into bed.

11. If you are a purist, make this a two-day trip instead of a turn-around, and do this two nights in a row. Hope you enjoy your sim session.

12. And to simulate TSA have a complete stranger touch ya "junk"


Not too far from the truth if it be told

Bernard

[Shiv Mathur]

Superb, Bernard ... couldn't stop laughing !

[Hardy Heinlin]

Re motion: I think it depends on what kind of flights you want to do.

If you do a normal takeoff, a normal climb, normal cruise, normal approach, normal landing, shallow turns, no significant wind, no engine failure, then motion adds just a little bit of pressure during departure and rollout. Very high cost/effect ratio.

But ... I, for one, when I'm in a sim, don't want to do normal procedures, rather want to do the unusual stuff, bad weather, tricky circlings, turbulences, windshears, engine failures, I would really miss the motion when it's off.


Cheers,

|-|ardy

[the mad hatter]

back to motion, Hardy makes some very strong and very valid points for having a motion base, windshear alone makes it worth while, its really comes down to how deep are your pockets 3 DOFF or 6 DOFF and what does one intend to do with the sim... i.e.  is it a training aid as in a sexy flight deck procedures trainer, Do you want to log time in it ? and if so would you require a type rating, or do you want to do re current training ot jet transition transition etc the 747 is to big of a handful (workload) and the learning curve is steep, for most it is not a light 737 or is it a entertainment system each of these things have their own requirements and levels of fidelity and fidelity equals money. (then it needs a more permante home), then you have to get the various authorities and approvals  

Some things can not be experienced/taught in a fixed based box and motion becomes mandatory. Then if one is going the motion route then the visual system becomes a major consideration... My thoughts are software software software, then control items in terms of fit feel function, then decide what is going to be tactile and what is not  would I like motion in my life time "YES" I guess the question I asked myself is what is it I am doing rebuilding the aircraft or emulation of a CAE level D sim on a tighter budget?  With this question answered PSX will allow builders to take it to whatever level they wish is my take and the software is the heart of the whole thing right?

Now all that being said who has plans for a motion platform 3 or 6 doff that will hold 5000lbs does not require three phase power has a small foot print and palatable price tag?

[Hardy Heinlin]

... and the software is the heart of the whole thing right?

The whole thing is the heart :-)

[Jeroen Hoppenbrouwers]

I sort of agree with hoppie about not mounting the visuals on the platform however dont think that would work well.

Think about it this way: if the motion platform "just" does 10-20 cm on each of the four corners, which is the "simple" way to build it, you cannot do movements that would truly change your view out of the window.

But you CAN make your life as a pilot quite interesting, by all this bumping and shaking around.

My theory is that in case of these "small" movements, the pilot's head moves enough to mask out that the visuals don't move with the bumps. It's not "flying movements", it's "uneven asphalt".


Jeroen

[farrokh747]

http://www.inmotionsimulation.com/

http://www.simsensation.nl/simsensation/Boeing_737.html

http://www.mycockpit.org/forums/showthread.php/19441-update-on-the-motion-project.?highlight=simsensation

http://buggies.builtforfun.co.uk/Sim/index.html

and of course matt's -


fc

[SwissCharles]

Many thanks, folks, for your very interesting feedback!
(those who answered to Blake did probably mean me, Charles?    )

Bernards post on living out the experience in a closet sent me rolling on the floor and going for a ahemmm...leak..., forgot the hat in the process, though  :?  

I totally agree with the mad hatter. I flew many hours in a pro 744 sim without motion (so we could hop out and fetch coffee, hey, it was 03:30 in the night) and it is not needed. The most effect you have during taxi and in turbulence.

I would change your estimates though.
65% visual.
25% sound.
10% motion.
Jeroen

Thats an interesting statement! When I last sat in an simulator (Saab SF 340 in Stockholm in the early eighties) I had been totally oblivious re these shares on the total experience.

So, with this limited travel I got I tend to agree with what Jeroen said:

Charles: your idea would probably work fine if you focus on shaking and rattling, and leave most swaying and G-faking completely out. If you cannot tilt 30 deg then it isn't worth it. But those actuators would make for a great bumpy ride and convincing touchdowns.

Jeroen

I don't have autojacks in mind, though    but vertically operating, sturdy short-throw jacks - preferably working on a dedicated single phase 16 amp circuit.
It would remain to be seen, if in addition to rattling and bumps or as Bernard mentioned  stick shakers, butt kickers and surround sound - and in combination with large wrap around visuals - an, albeit small, 'nudging' at the right time would sufficiently help in tricking the brain (or whats left of it) in 'extrapolating' these motion cues.
Say, during rotation in pitch, where the visuals 'rotate' to, say 18 ANU and the two rear actuators would move, say 4 inches down and the front ones4 inches up at just the right time.

Am I taken in by a wrong assumption here? When Jeroen writes:

It would definitely be worth a try to NOT put the visual system on the motion platform. Hefty bumps may become more convincing if the visual does NOT move with them.
Jeroen

Well, the scenery very definitely doesn't move with turbulence but the a/c does. Plus the alps certainly stayed put when I last checked - silly me! Or do I miss something here?

PC, thanks for the link. Me lacks at least 3 stories to house a beast like this   .  Garry you are a genius having programmed that!!

Charles

[Jeroen Hoppenbrouwers]

Charles: when rotating for takeoff, the sensation you feel most likely isn't due to the rotation itself, which is just 10-15 degrees. It's the vertical accelleration you feel after rotation, and this is notoriously hard to simulate, even in the big sims.

On the other hand, the accelleration during the takeoff roll and the decelleration during rollout are relatively easy to simulate by pitching the sim backward and forward.

Like somebody else said here before, it is not the attitude changes that you want to put on the platform. It's the accellerations. Some of these are in the horizontal plane and these can be simulated convincingly by tilting the platform, as this can be sustained. Vertical accellerations aren't well possible, but vertical bumps are easy.

If you have sufficient tilt to do fake accellerations, you need to mount the visual system on the platform to complete the illusion. If you just bump the platform to simulate turbulence and uneven asphalt, you likely do not need to mount the visual system on the platform. However this is my guess, I never tried it out.


Jeroen

[John Davis PC]

Thanks for the description Bernard .... Looks like we are getting Worldflight 99% realistic now