Accelerometers for maritime uses

On Dec 26, 10:30&#4294967295;am, Rune Allnor <all...@tele.ntnu.no> wrote:
> On 22 Des, 23:13, pnachtwey <pnacht...@gmail.com> wrote:
>
> > but &#4294967295;noise on
> > top of 12 bit resolution is not good.
>
> Again, check what data the MRU actually produces. 12 bits is
> about 4 significant digits, which ought to be sufficient if the
> device produces attitude angles, as it would do if it reads
> gyro alignments.
>
> Rune
The platform that is being controlled must respond to the wave action
and compensate for the relative motion.   This is essentially gearing
in 3D.  When gearing to an reference it is always better to use more
than just the reference's position.   I like to estimate a velocity
and acceleration too.  This way the slave object can use feed forwards
to estimate the control signal directly instead of waiting for error
to be corrected by the closed loop control.

As I said above, it have it worked out now.  A simple alpha-beta-gamma
filter does the trick.  I have a simple simulation program.  The
feedback is 14 bits but I simulated it with 12.  It just takes some
math that the customer will have to see.  I prefer not to scare them
too much.  I think I scared them too much as it is but I rather they
go into this with their eyes wide open than be blindsided by the math.

Peter Nachtwey