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BNO055 Vibration Issues when Vehicle Mounted
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BNO055 Vibration Issues when Vehicle Mounted

by bgoddard79 on Mon Jun 08, 2020 10:29 am

Hello,

I have been using a BNO055 to detect heading on a vehicle mounted camera gimbal. Contrary to what most people report this actually works pretty well. I have had a lot of success with this setup with only one significant problem.

Over an extended period of time while driving at highway speeds the tilt and roll axis will slowly drift away from level. Once these values drift past a particular point (~+- 135 degrees) the sensor assumes the vehicle has become inverted and it flips the heading by 180 degrees. The correction math I use is then backwards and the gimbal just sits an oscillates back and forth. This typically takes anywhere from 30 min to an hour to occur. If you stop at any time things correct themselves. I have tried everything I can think of to better isolate the sensor from vibration with no luck.

Any ideas out there that might help here?

Here is a brief video of what I am going for when this is working well.

https://youtu.be/B6UfKCKe4Jo

bgoddard79
 
Posts: 2
Joined: Mon Jun 08, 2020 10:17 am

Re: BNO055 Vibration Issues when Vehicle Mounted

by jps2000 on Tue Jun 09, 2020 1:08 am

Impressive video
These consumer IMU´s use some tricks to compensate for gyro drift in their fusion software. In particular they require to hold the sensor at rest from time to time that stable acc and magnetometer readings are present. Then it is assumed that there is no rotation and gyro drift can be compensated for internally.
Continuous movement can also cause some runaways of orientation. The BNO080 is doing better in this respect.
Drift is mainly caused by temperature changes of the sensor. (Assuming supply voltage is constant) Your observation about the time when it occurs points also in that direction.
Hence you may try thermal shielding of the sensor (foam isolation) and switch on some hours before your measurements. A better approach may be using a thermostat housing and keep the sensor heated above ambient temp ( 50-60 deg).
To check these assumptions try to evoke the failure with a hair dryer or cooling spray.
Vibration you can damp by mounting the sensor on a (relatively) heavy mass ( piece of metal) and then pack everything in soft foam in a plastic housing. This works as a mechanical low pass filter.
So first do some experiments to see how you can influence the failure and in which direction it goes.
A software patch comes at latest possible moment.

jps2000
 
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Re: BNO055 Vibration Issues when Vehicle Mounted

by bgoddard79 on Tue Jun 09, 2020 6:33 am

That is a good thought on temperature. I have noticed that it seems to run better after it has been up an running for a while. As far as vibration isolation goes I have done quite a bit to isolate things as best I can. I have used rubber isolation pads at both the PCB mount and on the feet of the entire device. I think this is about as good as I can do with the thing mounted out in the wind at highway speeds. I will keep playing around with a few different ideas.
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bgoddard79
 
Posts: 2
Joined: Mon Jun 08, 2020 10:17 am

Re: BNO055 Vibration Issues when Vehicle Mounted

by gammaburst on Thu Jun 11, 2020 8:02 pm

Simple drift would be my first guess too. The BNO055 "automatic calibration" is undocumented and sometimes behaves unwisely or poorly.

Or maybe coning error. That can rectify (convert) vibration into angular drift. I would be surprised if the BNO055 firmware provided any correction for it.

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Please be positive and constructive with your questions and comments.