07-23-2021 10:29 AM - edited 07-23-2021 10:32 AM
I am evaluating BMI088 for navigation applications.
I need to verify the gyro nonlinearity error within a relatively small angular range (-10dps to +10dps).
The test was done in the following steps.
3.1 The gyro output was first calibrated using best fitting straight line to correct scale factor and bias error.
3. 2 The calibrated gyro output at each step was compared with the set value to calculate the error which is considered as nonlinearity.
We can clearly see that when the rate table rate crosses 0dps, there is a jump in the gyro output. We tested a few units and all the units show similar behavior.
It seems there is some ADC error. Could any one help to explain and provide some kind of configuration to fix this? Thank you.
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07-27-2021 08:45 AM
Is your rate table a standard test tool?
07-28-2021 02:29 AM - edited 07-28-2021 02:40 AM
Yes, it is a standard tool and should be accurate enough.
Actually, we simultaneously tested many types of IMUs including BMI088 and BMI160. All other units seem fine.
BMI160 also has nonlinearity issue, but different from BMI088. Please see fig below. However, since we will not use BMI160 in navigation application, I didn't include this in the original post.
As a comparison, I also provided results from another low-cost IMU.
08-02-2021 04:08 AM
In order to evaluate the nonlinearity (error) value of BMI088, could we now what gyroscope range you set?
08-03-2021 07:27 AM - edited 08-03-2021 07:28 AM
The FSR is 500 dps. I believe the nonlinearity error should be well with in spec because integral nonlinearity is specified here.
However, the issue I mentioned seems a systematic error and should be able to be fixed.