Meant to be Seen

I am considering using a 3 axis gyro sensor that has a magnetometer to correct for drift, but I'm not sure if the magnetometer will alter the razer hydra's magnetic field. I've heard on the forum that you can calibrate these types of things. But the sensor, in my case, will constantly be moving/changing its rotation and position.(even tho i know that with a 3 axis gyro you can't track position). When the hydra is calibrated, would the gyro have to be in the same spot or can it still move around as long as its still in its magnetic field?

Magnetometers do not create magnetic fields, it mearly measures the earths own magnetic field as far as I know.
The Hydra base station creates the magnetic field for the three coils in each controllers to measure, and thus i would imagine that it would be the hydra base station disturbing the magnetometer.

However, the magnetic field the magnetometer measures is earths own and much more powerful that Hydras - so I doubt it will be able to interfere with the magnetometer.
Dont take my word for it tho, this is just my two cents.

Thanks For the reply! I'll make an update once i get the new equipment

On the contrary, I would think that the Hydra's field is much more intense at close range.

The funny thing is that the Hydra's field oscillates, so if you want to do some active software correction on the magnetometer to filter out the hydra, it might be easier to find the base-line earth's unoscillating field (than if the hydra was not oscillating).

I recall another post saying that the engineers who made the PS Move found the magnetometer so unrealiable that they just threw that data out when doing the fusion. And that was WITHOUT any purpose-built magnetic field emitters nearby.

According to Sixense, the Hydra's field strength is 20x weaker than the Earth's (so ~2uT). Of course, that figure doesn't really help considering that the field strength weakens as the inverse square of the distance from the electromagnet. So is the field 20x weaker in the center of the magnet, or a couple feet away from it?


If the Hydra's field strength is indeed substantially lower than the Earth's at the expected operating range, then you can probably just subtract a couple uT from each magnetometer axis (though it's probably not even necessary). What's more important is performing hard and soft iron calibration if the sensor is placed near a permanent magnet, or other ferrous materials - otherwise the resulting data could be useless.

What kind of equipment is needed to measure the magnetic field strength? I have a hydra, and If I could locate some measuring equipment I could do a test.

Namielus wrote:What kind of equipment is needed to measure the magnetic field strength? I have a hydra, and If I could locate some measuring equipment I could do a test.

Since it's not a static field, measuring it is not really straightforward. It might be possible to log the raw feed from a stationary magnetometer, and pick out the largest discrepancy between the data from when the Hydra was enabled and disabled.

There's probably not much to worry about as Palmer had mentioned that he didn't experience any interference issues between the Hydra and the Rift's head tracker.