Razor 9DOF - magnetometer drift

Hi,

I'm currently building my quad and noticed that I have a lot of motor vibration causing a lot of noise on my IMU data. I use the razor 9dof. And yes I allready read that a lot of poeple don't like this imu for mulitcopter projects because it is sensitive to noise. But I got this imu so I wan't to finish my quad with this one.

When I was looking at the raw data comming from the  HMC5843 (triple-axis, digital magnetometer sensor). I noticed some strange behaviour that I can't explain. I noticed that the data comming from HMC5843 is not sensitive to vibration, because amplitudes stay the same in all cases at all motorspeeds. But when I powerup the motors the data shifts upwards. This happens on al 3 axis (x,y,z)

I think this behaviour will cause drift when I use the AHRS code with DCM calculations. Because the data shifts up lineair to my motorspeed I should be able to hardcode a compensation. But I would like to understand why this happens? someone has en idea?

Tags: 9DOF, DATA, HMC5843, RAW, Razor

Views: 289

▶ Reply to This

Replies to This Discussion

Permalink Reply by Allen Babb on March 19, 2012 at 6:53pm

EMF noise caused by the motors. See if you can do a frequency spectrum analysis of it and you may be able to filter it out in software (or even hardware if your have the space).


DeveloperPermalink Reply by Doug Weibel on March 20, 2012 at 6:37am

DC currents - like from the battery to the esc - cause static magnetic fields that will affect the magnetometer.  This is what you are seeing; as you increase the throttle the current increases, and the magnetic field produced by your power system increases.  You need to work on your layout to isolate the magnetometer from unwanted sources of magnetic disturbance.

Permalink Reply by Allen Babb on March 20, 2012 at 3:06pm

Doh, forgot about DC supply currents. Wonder if twisting the + and - supply wires would do any good, you know, like they do with twisted pair's.

RSS

Social Networking

Top Content 

1 ArduPlane 2.73 released

ArduPlane 2.73 released
2 ArduVTOL

ArduVTOL
3 How to analyze a crash?

How to analyze a crash?
4 HD video for UAV's

HD video for UAV's
5 Mapping Mission Ride Along

Mapping Mission Ride Along
6 APM Copter 2.9.1.b has been released

APM Copter 2.9.1.b has been released
7 Arducopter 3Dr or Phantom

Arducopter 3Dr or Phantom
8 3 axis Camera Gimble connections.

3 axis Camera Gimble connections.
9 Mechanical Hands From A MakerBot: The Magic Of Robohand (From Makerbot blog news)

Mechanical Hands From A MakerBot: The Magic Of Robohand (From Makerbot blog news)
10 ArduVTOL - Wingcopter - Flight Report Nr.1

ArduVTOL - Wingcopter - Flight Report Nr.1

Contests

Season Two of the Trust Time Trial (T3) Contest has now begun. The fourth round is an accuracy round for multicopters, which requires contestants to fly a cube. The deadline is April 14th.

A list of all T3 contests is here. 

Groups

Advertisement

© 2013   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service