Platform 2 Prototype - nose up.
PAGE 1 is here
Page 3 is here
After roughly three weeks in the workshop
(part time) the parts and
assembly work of the prototype Platform 2 is done and it is now
up and running. The design works more or less as expected,
although there are probably one or two areas where it could
do with a few tweaks.
The three linear actuators seem well
able to move the platform with pitch, roll and heave motions.
I'm using the single chip SPU and PID servo controller
software to drive it. Importantly the half-scissors load
support mechanism with bungee cord springs is effective in
balancing the vertical platform load so that the actuators
are left to accelerate the mass of the platform.
area where I have tweaked the design is the support leg
construction which has turned out to be too flexible torsionally
- this effects the leg rigidity when constraining
fore-aft movement of the platform. I've stiffened this by
closing the x-section of the legs (good for torsional
stiffness) and adding thicker flange plates to further
increase the polar moment of area.
Other than these changes the design seems to work well under
nearly full working loads - loaded up with bags of gravel and me.
Below are three short movie clips showing the platform in motion.
The first two show principally heave motion generated during a
flight in stormy weather, the last clip shows the platform
motion during a quick takeoff - I've still to adjust the motion
controller settings to get the magnitudes of each DOF movement
And just added - Clip 4
this one with the platform "loaded" with roughly 110kg and with
some modest flight movement generated by FSX, I'll do something
more adventurous shortly! NB the annoying squeak is rubbing
between two bits of wood somewhere - I haven't found it yet.)
One interesting behaviour that has emerged is the way in which the
bungee cord spring arrangement allows sideways motion of the
platform to occur if it is pushed in that direction. The normal
movements of the actuators don't induce much lateral movements
however fast rolling during stormy weather does induce some
sideways or sway movement in the rig. If a way of actuating sideways movement could be devised the
platform would be able to act as a 4 DOF platform. It would be possible to
eliminate any sideways motion by fitting a partial
Sarrus mechanism, but
I'm going to leave it at the moment to see what it feels like. I
have a feeling that some small degree of sideways oscillation
may benefit the simulation experience.
It looks as if I could also make a few useful changes to the
motion driver software and setup program to provide better help
for builders with this type of three-point support platform, so
I'll be looking into that. (This is now done and the
latest version of the software
includes a new configuration program specifically for 3-point
support type rigs.)
Below are a few photos of the rig as it currently stands - I'll
keep you posted.
I'm now looking at the design of the computer
monitor support and a enclosed hood so I can do some testing to
get a proper feel for the quality of the motion cues. Go to
© This site is
copyrighted, If you'd like more information or have any
comments please contact me at