[jleibs]

First of all, there's the obvious "search for accelerometer" and read a bunch of other threads. I'll let someone with more FIRST experience than I point you to the ones that are actually useful.

Second, make sure you are using timer interrupts, so that the change in time between measurements is reliable. (Once more, someone else can provide better advice than I as to how to make this happen).

Mounting the accelerometer in a piece of foam is a pretty good idea as a form of a mechanical low-pass filter.

I believe, there are some tricks that can be done with a capacitor to act as an electrical low-pass filter.

If that's not enough, you're going to have to add a software low-pass filter as well. An average of the past N samples is a suboptimal version of this, but at least a decent place to start. However, the problem with a software lowpass filter is that it can only operate at your processor frequency and I suspect the noise you are trying to filter out is at a higher frequency than your processor is running.

Out of curiosity could you post a plot showing one of the shocks that you believe to be throwing off your data?

Could anyone tell me a little bit more about the actual physical mechanism of the KOP accelerometers? Are these returning a continuous voltage that is proportional to acceleration, or are they clocked at some particular frequency?

Most accelerometers I have worked with return a digital delta-v, which is the integration of the acceleration over the time-step of their frequency of operation. This is clearly preferable to returning an instantaneous sample of acceleration. I'm a software guy and not an EE, so I don't tend to ask what's going on under the hood in so far as the amount of processing the accelerometer is actually doing.

In any case, believe it or not, basing your navigation on wheels tends to be a lot more robust than accelerometers. Though, in an ideal world, you would combine the two of them. I expect most teams have had pretty decent success combining encoder-based wheel odometry with using gyros to estimate rotation changes.