rec.autos.simulators

by **pdot..** » Fri, 24 Nov 2006 00:29:19

I've been reading about the Frex motion system. It looks impressive in
the video! Lots of movement.

Has anyone discussed the inaccurate motion cues that Frex system
provides? The Frex system is generating motion cues opposite from what
occurs in real life!

For instance, the inner-ear sensations that the driver experiences will
all be reversed from real life. Also, the pressure and tension changes
the driver feels between his body and the seat while the seat is in
motion are reversed from reality.

The Frex approach seems to be to move the head of the driver around in
the way it would in a real car. From that perspective the system seems
OK, except that eye position movement of the driver is already modelled
in current simulations. I guess you could just turn off the simulated
head movement in the simulation while using the Frex system.

Still, I'd hate to train and practice in that device, then jump in a
real car expecting to go fast!

Pat Dotson

by **Trev** » Fri, 24 Nov 2006 04:13:22

> I've been reading about the Frex motion system. It looks impressive in
> the video! Lots of movement.

> Has anyone discussed the inaccurate motion cues that Frex system
> provides? The Frex system is generating motion cues opposite from what
> occurs in real life!

> For instance, the inner-ear sensations that the driver experiences will
> all be reversed from real life. Also, the pressure and tension changes
> the driver feels between his body and the seat while the seat is in
> motion are reversed from reality.

> The Frex approach seems to be to move the head of the driver around in
> the way it would in a real car. From that perspective the system seems
> OK, except that eye position movement of the driver is already modelled
> in current simulations. I guess you could just turn off the simulated
> head movement in the simulation while using the Frex system.

> Still, I'd hate to train and practice in that device, then jump in a
> real car expecting to go fast!

> Pat Dotson

It's simulating G-forces. It's cheaper than a full-motion platform.
People say it feels right.

by **pdot..** » Fri, 24 Nov 2006 05:11:10

Obviously.

My point is that the Frex moves in a way such that the eye position of
the driver is changing reasonably close to the way it does in real life
in response to G forces, but as a result, those same movements apply
real G forces to the body of the driver that are completely inaccurate.
In fact, the real G forces that the driver feels while the chair is
moving are reversed from what happens in real life.

Is it cheaper than a motion platform? Much! Is it better than no
motion? Surely. Does it accurately present real world motion cues to
the driver? No. Is it suitable for race driver training? I don't
think so.

Pat Dotson

> > I've been reading about the Frex motion system. It looks impressive in
> > the video! Lots of movement.

> > Has anyone discussed the inaccurate motion cues that Frex system
> > provides? The Frex system is generating motion cues opposite from what
> > occurs in real life!

> > For instance, the inner-ear sensations that the driver experiences will
> > all be reversed from real life. Also, the pressure and tension changes
> > the driver feels between his body and the seat while the seat is in
> > motion are reversed from reality.

> > The Frex approach seems to be to move the head of the driver around in
> > the way it would in a real car. From that perspective the system seems
> > OK, except that eye position movement of the driver is already modelled
> > in current simulations. I guess you could just turn off the simulated
> > head movement in the simulation while using the Frex system.

> > Still, I'd hate to train and practice in that device, then jump in a
> > real car expecting to go fast!

> > Pat Dotson

> It's simulating G-forces. It's cheaper than a full-motion platform.
> People say it feels right.

by **Trev** » Fri, 24 Nov 2006 06:05:16

Have you tried it? It tries to give you seat-of-the-pants feel. As
that's the aim, the movement is correct.

>>It's simulating G-forces.

> Obviously.

> My point is that the Frex moves in a way such that the eye position of
> the driver is changing reasonably close to the way it does in real life
> in response to G forces, but as a result, those same movements apply
> real G forces to the body of the driver that are completely inaccurate.
> In fact, the real G forces that the driver feels while the chair is
> moving are reversed from what happens in real life.

> Is it cheaper than a motion platform? Much! Is it better than no
> motion? Surely. Does it accurately present real world motion cues to
> the driver? No. Is it suitable for race driver training? I don't
> think so.

> Pat Dotson

>>>I've been reading about the Frex motion system. It looks impressive in
>>>the video! Lots of movement.

>>>Has anyone discussed the inaccurate motion cues that Frex system
>>>provides? The Frex system is generating motion cues opposite from what
>>>occurs in real life!

>>>For instance, the inner-ear sensations that the driver experiences will
>>>all be reversed from real life. Also, the pressure and tension changes
>>>the driver feels between his body and the seat while the seat is in
>>>motion are reversed from reality.

>>>The Frex approach seems to be to move the head of the driver around in
>>>the way it would in a real car. From that perspective the system seems
>>>OK, except that eye position movement of the driver is already modelled
>>>in current simulations. I guess you could just turn off the simulated
>>>head movement in the simulation while using the Frex system.

>>>Still, I'd hate to train and practice in that device, then jump in a
>>>real car expecting to go fast!

>>>Pat Dotson

>>It's simulating G-forces. It's cheaper than a full-motion platform.
>>People say it feels right.

by **pdot..** » Fri, 24 Nov 2006 10:22:55

I haven't tried it - only saw the video. Have you tried it? I'd be
interested to hear what you think about it.

As I've outlined, I believe the movements of the Frex SimConMotion
create inaccurate, conflicting motion cues. Please tell me where I'm
wrong.

Pat Dotson

> Have you tried it? It tries to give you seat-of-the-pants feel. As
> that's the aim, the movement is correct.

by **Plowbo** » Fri, 24 Nov 2006 11:53:29

I can tell you where you are wrong, 1st off your simulating the forces
applied the the body of a person, who is in the***pit of a car/plane/train
(stationary object inside a moving object) which is all done in combination
with inherent visual cues from the games (notice the screen moves with
you)...

But, ride in the back of my pickup, when I gass the throttle, and you are
standing up, you will fall backwards. It isnt really because you did
anything but shifted the direction of center of gravity... in a chair
however if mounted sturdy, you would just feel increased "G" forces which is
being basically weight distributing across your bones and muscles. Much in
the way tipping a chair backwards makes your body "shift it's weight" from
the bottom of your ***to the back and {arms? as you catch yourself in some
cases}... So the tilting platform to the right, to simulate the body being
in a tight left turn, well It seems to simulate gforce loading of bones and
muscles. Now, I agree, that the Frex cannot really simulate accurately, the
forces of you hitting the wall at anything above running barfoot 12 year old
could do top speed, I would guess for no other reason than legal liability
as death could happen (and power demands LOL)...

If you have not tried the "state fair" simulation movie theater trialers,
your missing out, and I do know that when the picture dies, the motiions of
the chairs and stuff are downright goofy and you are left with WTF feelings,
but at the same time, if you dont have your tongue just right you will
almost bite the damn thing off...

> I haven't tried it - only saw the video. Have you tried it? I'd be
> interested to hear what you think about it.

> As I've outlined, I believe the movements of the Frex SimConMotion
> create inaccurate, conflicting motion cues. Please tell me where I'm
> wrong.

> Pat Dotson

>> Have you tried it? It tries to give you seat-of-the-pants feel. As
>> that's the aim, the movement is correct.

by **Trev** » Fri, 24 Nov 2006 16:36:33

Make your statement here:

http://forum.rscnet.org/forumdisplay.php?s=&daysprune=30&f=809

> I haven't tried it - only saw the video. Have you tried it? I'd be
> interested to hear what you think about it.

> As I've outlined, I believe the movements of the Frex SimConMotion
> create inaccurate, conflicting motion cues. Please tell me where I'm
> wrong.

> Pat Dotson

>>Have you tried it? It tries to give you seat-of-the-pants feel. As
>>that's the aim, the movement is correct.

by **pdot..** » Sat, 25 Nov 2006 00:11:56

That's Newton's first law. The truck accelerated, but there was
nothing applying the acceleration to the body of the person who is
standing up. So the person's body stays at rest and the person falls
down as their feet get pulled out from under them.

That's Newton's second law. Now the chair is applying the acceleration
to the body of the person, and the person is pressed backward against
the chair. This is where the Frex system gets it wrong. Here's why:

Say you have a simulation of a person sitting in a sturdily mounted
chair in the back of a pickup truck. The simulation is controlling a
Frex SimConMotion system. The simulated truck is at rest and you are
sitting in the Frex seat. Now the truck goes full throttle. What does
the Frex seat do? It moves quickly backward. If you aren't belted in
the seat, the seat will slide right out from under you. The only thing
stopping you from sliding forward out of the chair is the harness.

Is this what happens in real life? Of course not! If you were
harnessed in the seat of a real pickup truck you will never feel
forward pressure against the harness while the truck is accelerating
forward.

This opposite reaction created in the Frex seat is called a
"conflicting motion cue". It's a cue that conflicts with reality, and
with other cues that may be realistic.

Yes. This part of the Frex system is OK. Using gravity to simulate
lateral force by tipping the chair. I'm not saying there is anything
wrong with this part. If you tip the chair and leave it there, it can
simulate a weak but realistic lateral force.

But...

I specifically said "while the chair is in motion". The problem is not
what the chair feel like while it's stopped. The problem is what it
feels like while it's in motion. If you've seen the video you have to
agree that the seat is in near constant motion.

For the reasons I've stated, ANYTIME the seat is in motion it is giving
a conflicting motion cue. There is no denying this. It doesn't take
any more than an 8th grade level of physics education to understand.

There is a thread in the***pit building section of RSC where a guy
from Force Dynamics discusses this issue (not specifically in regards
to Frex, but regarding the general design of a motion platform).

I'm not saying the Frex system is worthless. It looks like a lot of
fun and I'd love to have one. But at the same time there are inherent
problems with its design if you are looking for high fidelity motion
cueing.

Pat Dotson