Decent Gyro chips?

That isn't precession, it's just the rotation of the Earth. The distinction is that when something precesses, its axis moves with respect to an inertial frame, due to an applied torque component perpendicular to the rotation axis. Your gyro's rotation axis was merely remaining stable in an inertial frame--yet another successful test of the law of conservation of angular momentum. Precession is what spinning tops do when they aren't supported at their centre of mass.

Take a wheel of a bicycle, and spin it while holding it up vertically by one end of the axle. It will precess due to the torque of its weight acting on half the length of its axle. If you hold both ends, it doesn't precess because there's no torque applied. Torque applied along the rotation axis also doesn't cause precession--it just changes the rotation rate.

Cheers,

Phil Hobbs

Yes. I have mounted one in a car for use as an accellerometer and compass. If I pull up or brake, the sensor thinks it is being tilted. These sensors are great for head and motion tracking.

The sensor can be set to include more or less of the earths magnetic field into its calculations. Xsens is also very keen on supporting their customers. As far as I know they are also working on a version of their software which doesn't has the false tilt problem.

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Reply to nico@nctdevpuntnl (punt=.)
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Not entirely true, the sensors can be compensated for magnetic disturbances. I'm using one as a compass inside a car. The error is less than 5%.

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Reply to nico@nctdevpuntnl (punt=.)
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g=2E

ree

5% of what? Bearing accuracy (18 degrees)? Time (1.2 hours per day)? etc,etc,etc

And how do you test for it?

Bearing.

Drive around with the car using a route on which the same straight roads are passed in both directions.

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Reply to nico@nctdevpuntnl (punt=.)
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Un bel giorno Luhan digitò:

I'm afraid not, and neither are roubles. :)

However, it's not that much for a sensor of this kind, someone asked me twice as much just for a triaxial accelerometer...

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asd

How about comparing to GPS bearings (which depend on movement, I know).

But it doesn't maintain its position, it precesses. The plane of the oscillation rotates at a rate of something like 1 cycle every 36 hours at mid-latitudes. The period of the precession (360 degree rotation of the plane of the oscillation) is 24 hours / sin(latitude).

Cheers,

Phil Hobbs