BMI088 bias jump around 0dps

[dxglaw]

Hello.

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.

1. The sensor was fixed on a rate table. The rate table rotated from -10 dps to 10 dps with a step of 0.1 dps. The rate table stayed at each step for 12s.
2. Collect gyro output when the rate table stayed at constant angular rate, and the gyro output was averaged to remove noise.
   
3. Compare the Z axis gyro output with the rate table set rate.

   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.

4. The test was repeated for three times.

 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.

nonlinearity error

[BSTRobin]

Hello dxglaw,

Could you give the feedback in previous message?

[dxglaw]

Hello BSTRobin,

sorry for the late reply.

I only tested the Z gyro because in our application, such jumps in the X and Y axis should not be a problem.

I can explain a bit about our application. It is a navigation application with IMU and RTK GPS.

When GPS is available, this kind of jump is no problem. However, the estimation accuracy of the gyro bias is lower because of the jump.

When GPS is lost, the IMU is combined with an odometer to estimate position. That is, the gyro is integrated for heading angle, and the heading angle is combined with the velocity from the odometer to calculate position. In this case, the Z gyro bias estimation accuracy and the stability of the Z gyro bias are critical.

[BSTRobin · Accepted solution]

Hello dxglaw,

We contacted you via mail with detailed communication.