For instance, the Wiimote doesn't have the dynamic range to handle the highest accelerations you can generate waving your arms, which makes it hard to use that kind of thing for athletic training.
It's just extremely hard to make a pure INS navigation system.
Even if you could measure your acceleration accurate to 0.00001 m/s/s, because it gets integrated twice to give position even that tiny error is going to give you a position that's out by 100m after an hour.
And measuring acceleration precise to 0.00001 m/s/s is a demanding task - like weighing a car so precisely you could count the pages of a book on the back seat.
That level of precision simply isn't available in the affordable MEMS market segment.
It bothers me when people go around labeling random stuff conspiracies like that's a legit dismissal. If they were 'gimped', they wouldn't be the only hardware. GPS is still gimped and will shut off over a certain height and speed specifically to prevent use in missiles. And the precision used to be regulated, not by expense, but to give the military the superior tool.
†Because it's "just" noisy you can wait, and average out the noise. If you stand in one place patiently recording your apparent position, for long enough, the average is much more accurate. Or, one station which knows exactly where it is uses short range radio to tell moving stations what the error currently is in the signal, improving their accuracy. The latter is known as DGPS and still makes some sense without Selective Availability because the ionospheric conditions will be similar at a short range too, reducing error from those.
>And the precision used to be regulated, not by expense, but to give the military the superior tool.
Which was, as I said, referring to Selective Availability, and has nothing to do with the arbitrary limits which are still imposed on US made receivers.
The price difference between a Wiimote and an OxTS RT3000 is because a high-precision sensors and super-low-noise electronics are difficult.
ITAR doesn't stop you and me from buying an RT3000 - the thing stopping us is the fact it costs as much as a midrange car.
But if you go to the ATM machine and pull out enough cash after entering your PIN number, you can pay enough to make it happen.
You can buy RLGN off the shelf for a couple thousand bucks. You can buy gyrocompass-capable MEMS off of digi-key for dozens of dollars (Murata). Its just market forces and cost. You don't need super stable IMUs for game controllers.