BNO055 hardware fusion is wrong at low angular speed

[schadocalex]

Hi, I use a BNO055 and I have a strange problem. At low angular speed, the intern kalman does not change the yaw value. If I turn manually the imu at about 3deg/s, the angle and the gyroscopes values returned by the fusion are static (there is some very few noise near 0). But above 5-10 deg/s it's working as expecting (and very well).

If I read raw input (without fusion), gyroscope values become good even at low speed.

Important note: I don't use magnetometer because of the huge metallic mass near the imu (the BNO055 is in IMU mode for fusion (acc+gyro)).

[kriswiner]

I have no idea what is happening here. This sounds like a question for Bosch... You might have to do the fusion on the MCU host using the raw sensor output...

…

On Mon, Oct 29, 2018 at 6:57 AM Alexis Schad ***@***.***> wrote: Hi, I use a BNO055 and I have a strange problem. At low angular speed, the intern kalman does not change the yaw value. If I turn manually the imu at about 3deg/s, the angle and the gyroscopes values returned by the fusion are static (there is some very few noise near 0). But above 5-10 deg/s it's working as expecting (and very well). If I read raw input (without fusion), gyroscope values become good even at low speed. *Important note*: I don't use magnetometer because of the huge metallic mass near the imu (the BNO055 is in IMU mode for fusion (acc+gyro)). — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#12>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qg49VMqqKwhvv1cnS6x4Jm2WXByDks5upwksgaJpZM4X_Opb> .

[schadocalex]

Well, after posting this I did ask Bosch directly (I found a official repo). But we can't delete issues so I let this one. They answered me, you can see the answer if you want: https://github.com/BoschSensortec/BNO055_driver/issues/12#issuecomment-433944642

Sorry for the trouble.

[kriswiner]

It is going to be hard (impossible really, without significant drift) to get accurate heading without a magnetometer but if all you care about is roll and pitch then Madgwick's 6 DoF fusion algorithm works well with well-calibrated accel/gyro data with even a modest MCU. https://github.com/kriswiner/MPU6050/blob/master/MPU6050Library/MPU6050IMU.ino

…

On Mon, Oct 29, 2018 at 9:32 AM Alexis Schad ***@***.***> wrote: Closed #12 <#12>. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#12 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qjXdd7XPDtgSFKz5CBBgfXqpRgRXks5upy2ygaJpZM4X_Opb> .

[schadocalex]

I have a very special case: I care only about relative yaw (relative since an old yaw position). I only want to know my position relative to a previous one, so I think with gyro it will be ok (I will comment with my tests results If you want).

The heading in my case will be given by others sensors than a magnetometer (that does not work in my case, I have 2t of steel and high DC power (about 10kW sometimes) near the imu).