Re: inertial systems

On Sun, 2004-05-30 at 12:04, John Carmack wrote:
> Was the code I gave Pierce any help in getting the 3D inertial 
> transformations working with your crossbow?  For really short flights with 
> no significant wobble you might get by with just integrating rates, but 
> eventually you will need 3D transformations.

Yes, although I've gotten a lot more from looking at the functions that
get data from the IMU and do the screen drawing. Your code has been
extremely helpful all the way around.

I hit a lot of bumps with just getting good data from the IMU. I think
most of the bumps were typical inexperienced programmer goofs. As an
example, the char array I put the IMU data into was not declared
'unsigned' - the checksum checking routine would then fail every time
the checksum should have been 128 to 255. Anyway, I am now getting good
data from the IMU, and when we move gizmo around the data looks like it
is changing similarly to how it is being moved.

I've never done graphics programming before, so looking at your code and
reading the OpenGL manual pages has got me on the right track for that.
I hope to have the display done tomorrow. That would allow us to move
Gizmo around and see similar motion on the computer display. Once we're
happy with that I'll add in the PID loops and try controlled flight. 

Matrix math has been the bane of my existence since college, but I think
I'm finally starting to grasp it.

> I just got a quote from KVH yesterday for their new 6DOF FOG IMU system -- 
> $25,000 and 10-12 weeks delivery.

Ouch. Would this be their "tactical grade" IMU? 

I'm starting to wonder if our IMU will be OK for Gizmo, and I'm sure
that it won't cut it for POGO and later vehicles.

Thank you for the code and help. I need to get back to coding.

Dave

-- 
David Masten <[email protected]>