billon@chopin.udel.edu (John Billon) (06/04/91)
Dear Sirs:
I'm interested in how Human vision affects human "standing
still" balance. VR technology seems like a good medium to use to get at
the roots of the issue.
But first here is the problem in greater detail. For one,
people don't stand still, they have a kind of subtle rhythmic trajectory
that they travel through, when they try to stand still. This can be
illustrated if you stand very close, with the side of your arm just
lightly touching a door-frame. So there is an orbit, a trajectory, that
is a solution to a set of equations that describe an 80% water-filled
structure with an incredible number of degrees of freedom standing
upright. I am curious about what are these solutions and how do they
relate to all manner of things.
1) Are they related to a person's psychological state of mind?
Clearly when people are extraordinarily depressed, they don't
stand the same way as when they are alert and keenly happy,
their necks tend to go forward a bit more, their shoulders
droop... etc. When someone is happy, it must be expected
that they would respond to such perturbations in a very different
manner.
2) Related to 1), When people age, how are these solutions affected?
When people are very young, how do they re-orient
themselves when their balance naturally goes
through it's periodic trajectory?
3) Now, why I'd like a real-time 3-space tracker, that I thought I could
make out of a video camera, perhaps taking care of the problem of
too much information coming in by only accessing 1 or two of the
camera output lines:
a) How is a person's balancing trajectory influenced by
a person's vision? For instance, suppose someone is out
on the outskirts of where there brain beleives they are
vertical, say, if standing vertical is 0 degrees,
and a person's balance trajectory is bounded by
plus or minus .25 degrees from vertical, and they're at .25
degrees, and their eyes are made to beleive that they're
at -.05 degrees, how will the trajectory respond?
Can a person be made to fall over?
This is vaguely related to having some independent
control over the inputs in the pole-balancing problem.
Some control over how, for instance, velocity is input
to the control system might be a good illustration
of this kind of idea. Very minor alterations would
probably make the pole completely un-balanceable,
if it had already been trained without such alterations.
4) What is the outer limit of how a person's standing balance trajectories
can be altered? Would a person's mood be affected by an altered
balance trajectory?
So, now that I've told you what I really want to study,do any of you
in VR-land have any advice? VR technology seems to be the closest thing that
would be applicable to my interests. I have vague hopes of someday
taking apart a data-glove or polhemus and using them as body-trackers
and trying to play with peoples' balance using nonlinear feedback.
I've found a few books in the library about muscle systems and rhythmic motion
that seem to be vaguely related to what I want to study. Are there any
labs out there working on the questions I have outlined above? Does anyone
know of any papers in relevant fields that might be of interest to me?
It would really be best if any replies could be emailed back to
me directly.
Thanks Alot!
John