[simpits-tech] Bike Sims; a physics lesson (was: Re: Air & Space Smithsonian....)

[Bubba]

Sean Galbraith wrote:
>
> To understand what happens you need to know a little about gyroscopic
> precesion <sp?>.

I knew about precesion, but there are other theories that sound good, too.
One is that you turn the bars right and the bike starts turning right, but
inertia leans the bike to the left. At that point the tires being on the
side overcomes the angle of the front wheel so the bike turns left.

> On my GSXR-400 track bike

Bastard ;) I want a ZXR400R myself (I think that's the right string of
characters, anyway) for a trackbike.

> As for using body weight  to steer a bike, yes you can, it's just not real
effective, but
> useful in
> some situations like exiting a slow corner with the front wheel in
> the air,
> while counter steering will still work to a certain degree, moving
> body
> weight, and standing on the relevant peg will be much more effective
> (don't
> ask me how I know this... <g>)

Ever hear of the No BS bike? It's a ZX6R with some bars and a throttle
mounted rigidly to the fairing stay. It'll just barely turn by leaning the
bike, but countersteering on the normal clipons is the usual 6R lightning
fast.

> Now to re-create this in a sim environment:
> -  Good luck :)
> - I agree with Matt's theory on G forces, I don't think you will want
> the "bike" to lean that much... otherwise with no balancing force you
> will tend
> to fall off the thing :) A bit like the whole motion cueing vs actual
> motion discussion for full motion sims....

Yes, but it does have to move at least, say, 10° since you can feel the bike
leaning when you start a turn. It doesn't have to go far, though.

> - I saw a  write up a few of years ago of a sim built by (I think)
> Honda
> for testing rider ergonomics.  They used a projected view, which had
> the
> lean angle in software, and a much smaller motion of the "bike".  The
> coolest part was that they had the road on an angle on either side of
> the
> bike so that the riders could get their knees down :)

Hmm... a couple of garage sale treadmills? ;) The projector would be very
nice, but not cheap... Hmm... put it where the headlight should be and use
an oversize screen. That'll do it.

> - Biggest problem I can see is creating the physical relationship
> between
> counter steering and lean angle.....

Pneumatics or really, really fast electric rams.

> Now bear in mind that not a lot is actually known and proven in
> regard to
> motorcycle physics.

For the sim it'll be more of an exercise in fooling the ears, eyes, and
brain. When we discussed this a bit a couple of years ago someone came up
with the idea of putting high volume blowers up front somewhere and
controlling the velocity with the throttle (or a speed output from the sim
if possible). That'll do a LOT to trick the brain. A tactile transducer
under the seat to simulate engine vibration would be needed, too. If played
in the dark with the sound turned up it would probably be enough to make
non-bikers sick.

Remember, as complicated as the brain is, it relies on a few constants to
keep things sorted. If you eliminate a real reference point, like seeing
vertical walls, and replace them with artificial ones, you can trick your
brain into thinking things are happening that really aren't. Putting
converging lines in your field of view works to make you think you're
moving, too. Years ago we tried an experiment in school. The darkroom was
all black and, naturally, dark. People would walk into walls that could be
seen, but didn't "see" them because their brains had no distance reference.
We put some reflective yellow and white tape down on the floors and walls,
all converging on a single point at one end of the room. If you walked in
the door and stopped you would feel like you were falling forward. A few
people fell backwards trying to compensate for it. A couple of people even
walked flat into the wall thinking it was many feet farther away. After the
room gave our advisor a migraine that sent her home for the day the
principal made us take the tape off even though he thought it was a really
cool experiment.

> I am a 10 year veteran of one on NZ's best (at least we like to think
> so)
> riding schools, and have specialized in road and racetrack work, and
> I'm
> still learning!

I'm going to my first trackday in August if everything works out right. I
actually bought my 7R from an instructor and have pics of it on the track.

> I have been lucky enough to have learned from some
> great
> riders including Aaron Slight (he's from my hometown) and I am still
> absolutely amazed at how much we don't know......

Colin Edwards lives about 15 minutes from here. I run into him every once in
a while around town.

> Oh, and when you get it finished I'll bring the beers, my leathers
> and Arai ;-)

And if you ask real nice I might let you ride one of the things in my
signature ;)
--
Steve
95 Buell S2 Thunderbolt
96 Kawasaki ZX7R
mysticz28@swbell.net
Jesus saves, Budda enlightens, Cthulhu thinks you'll make a nice
sandwich.