|
Publication date -
22nd December '08, |
|
DIY Motion Platform
Articulated Projector |
Projector Articulation System
(Further details on
Page 2,
see
Page 3 for NEW fixed
screen demonstration software.)
Recently I've been working on a exciting enhancement to DIY flight motion simulation. It is a
technique that looks well suited to low-cost DIY motion projects
that has been developed by
Professor Bill O’Riordan
of
ORB Research
here in the UK. The simulation enhancement involves manipulation of the
flight simulator's projected visual display in order to induce
and/or intensify the impression of motion experienced by the
pilot.
The ORB Research technique is to make
controlled, often subtle movements to the entire projected scene in
front of the pilot which, together with the platform motion,
further tricks the pilot into thinking that he/she is actually in
motion. The movements of the visual display are driven from
flight data extracted from the flight sim program in a similar
way to the main platform motion drive and are therefore
coordinated in real-time with the motion
of the simulated flight and the
platform physical movements.
This projector articulation technique is still at a
fairly early stage of development however strong immersion
effects are reported by ORB Research and there is
clear potential for the method to be used with a small displacement
motion platform to add to the options DIY'ers have for low cost
but effective motion platform projects. I do know that the
projector articulation method when running on my
Platform 3
design
produces an immersion level that scares the life out of my wife
-
she seems convinced in her efforts to control the aircraft that
she is actually in the air even though the scale of the
movements produced by the motion platform are quite limited. I
find that the effects do indeed enhance the motion immersion.
Effects
The best way to describe the effect may be to show
you a couple of movie clips.... In the Platform 3 prototype a
single projector is mounted above and behind the pilot's head
(see image above left) and this projects the main forward
scenery view on a screen in front of the pilot. The projector is
fitted with an articulated drive and is driven by the
V2 BFF Motion Driver software
to move the projected display. Here are a couple
of clips of the pilot's view....
|
Motion Cued Display -
Clip 1 |
Motion
Cued Display - Clip 2 |
Clip 1 shows the typical visual effects during
takeoff in a light aircraft - first a couple of runway turns to
show the yaw effects and then the takeoff. Clip 2 shows the
effects during level flight in a heavy storm so the movements
are a good deal more pronounced than those apparent during
normal flying - but they make the motion clearer for the clip.
There are two ways to view these clips. The first
is to concentrate on the "fixed" scene - say the LCD monitor
below the projected image, this way you clearly see the display
movement. The second is to concentrate instead on a scenery
object in the projected display - a tree, building or coast line
say. When I do
this the display movement seems to reduce in intensity and I'm
drawn into the simulated motion. You can
imagine that when the projected display occupies most of the
visual scene in front of you and it is combined with physical
movement of the platform the immersion effects might be quite
strong.
An important characteristic of the approach that is
worth pointing out is that the immersion effects seem to be
dependent on moving the whole display frame and not just moving
the image within a fixed display.....
Implementation
Modern
projectors are
generally quite compact and light and the physical mechanisms
required to move one can be fairly simple. Indeed on my
implementation, and on the ORB Research development rigs I've
seen, conventional RC type servos are used with simple mechanics
and drive hardware. A trickier element (as always) is the
real-time extraction and processing of flight data to develop
the projector's motion "cues" and in my work I've implemented this as an
integrated feature of v2 of the
BFF Motion Driver software.
|
Photo
courtesy of ORB Research, 2008 |
I opted for a partial Stuart type mechanism for the projector
drive mechanism (shown above). In this the projector is hung from a stiff
plywood plate which is supported at the rear on a ball joint.
Three servos support the front of the plate through a
triangulated Stuart type arrangement of tie rods and can drive
small vertical, horizontal and tilt movements of the projector
using "coupled" motion cues from the
v2 BFF Motion
Driver. These movements are magnified by the projector
"throw" and are reflected in the projected display. I've used a
Pololu Servo Controller to drive Hitec HS-815BB servos.
The image right shows an ORB Research prototype rig
which uses independent (uncoupled) servo drives for each of the
degrees of movement of the projector.
Development
The
ideas described here are at an early stage of development but I
think they have good potential for DIY builders and particular
thanks are due to ORB Research for making the ideas available to
the DIY motion platform builders' community.
There are issues regarding the optimal settings for
the display motion cues and this needs further testing and
tuning. Other development questions relate to what is best to
include in the projected display - should it be an external view
solely, or is it better to include elements of the cockpit
structure (eg a partial virtual cockpit view). I find the latter
has a better effect as it seems to provide a visual reference
which holds the attention of the pilot and better allows the
mind to accept the implied motion. A couple of other matters to
think about are the nature of the interaction between the moving
projected display and any "real" fixed cockpit panels there may
be and also how to deal with multi-projector setups.
On to Page 2
for more details......
-
see
Page 3 for fixed screen
demonstration software.......
© This site is
copyrighted, If you'd like more information or have any
comments please contact me at
Page Published
22nd December 2008
