HMC6352 digital compasss

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HMC6352 digital compasss

Postby commaster » Fri Jan 08, 2010 10:17 pm

I use the compass in "Heading" mode, and i can obtain the correct heading when the compass is rotated. However, when the compass is shifted parallel to its original position, the value of the heading changes. Shouldn't the value remains the same?
I would also like to know if there is any way to compensate the value of the heading when the compass is tilted?
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Re: HMC6352 digital compasss

Postby waiweng83 » Sat Jan 09, 2010 10:43 am

I'm sorry that the HMC6352 is not tilt compensated and it only works when the sensor is level.

BTW, may I know what is your application? why you need the compass to be tilt compensated?
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Re: HMC6352 digital compasss

Postby commaster » Sat Jan 09, 2010 5:23 pm

I use it for robot navigation, perhaps with tilt compensation the value will be more accurate.
And what about the first problem? The compass heading doesn't seem to be the same when placed in two different position, both facing the same direction.
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Re: HMC6352 digital compasss

Postby waiweng83 » Sat Jan 09, 2010 5:35 pm

You will need a 9-dof IMU if you need the tilt compensation in dynamic condition (When the robot is moving).

For your first problem, it's most probably the compass is affected by the magnetic flux generated by your motor. Try to place the compass as far as possible from any source of magnetic flux (Motor, solenoid, relay, or even wires carrying large current).
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Re: HMC6352 digital compasss

Postby commaster » Mon Jan 11, 2010 11:21 pm

How far exactly should I place the compass from the motor?
I am now testing the compass on table. It doesn't seem likely that the compass value is affected by those magnetic flux. No idea what goes wrong, please help.
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Re: HMC6352 digital compasss

Postby waiweng83 » Wed Jan 13, 2010 1:07 pm

commaster WROTE:How far exactly should I place the compass from the motor?
I am now testing the compass on table. It doesn't seem likely that the compass value is affected by those magnetic flux. No idea what goes wrong, please help.


There is no exact answer for this. It's really depends on how strong the magnetic flux from your motor. And bear in mind that the magnetic flux from the motor varies when the motor is running at different speed.

Maybe you can try to make your robot higher and place the compass at the highest position away from the motor. Alternatively, you can try to get the magnetic shield material which is used in computer speaker to cover up your motor. But I've got no idea where to get those thing... :(
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