Jake Brownson wrote:
>>> So is this idea insane?
>>
>> For some thresholds of sanity.  How accurate does it need to be?
>> For how long after starting from a known position?
>
> Accurate to within ~5 deg or better, for at least ~10 mins.

That is many orders of magnitude beyond what is achievable by itegrating
MEMS gyros and accellerometers.  So to answer you question, yes.

> I meant to specify 2-axis compass modules (which we can afford),

That just means it's measuring the magnetic field along two basis vectors.
That may be enough, but you don't have to buy a "compass module" to get the
magnetic field.  You could use your own Hall effect sensors, which is what
is in the compass modules.  There is nothing stopping you from using three
orthogonal Hall effect sensors, although getting the horizontal component of
the magnetic field will be useful too since you can use gravity to find the
up direction.

> The entire project is actually a nerf targeting system. We're mounting
> a distance sensor, wind sensor, and rotation/incline sensor system
> (what I'm working on right now) so that the user can aim at the
> target, push a button and the required trajectory will be calculated
> and the user will then be guided to the correct rotation and
> inclination to fire. The gun should be operated as normal (on the
> shoulder) so we decided not to just use a tripod (which would have
> made it a bit easier). So yes it's a pretty fun project :). This
> project was inspired by the airsoft (think paintball) team on campus
> hoping to make some sort of mortor system.

So why do you need to measure the rotation about the vertical axis at all?
Won't the gun rotation with the sight since it's on your shoulder?  Why not
instead of "Show me what to hit and I'll compute the firing parameters"
instead "I'm showing you what you'll hit if you fire now."?  Then the signt
and gun can be rigidly connected and angular position in the horizontal
plane becomes irrelevent.


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