Reduce false positives in pre-flight accel bias check #11350
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dagar
reviewed
Jan 30, 2019
| success = false; | ||
| goto out; | ||
| } | ||
| } | ||
|
|
||
| if (fabsf(status.states[13]) > test_limit || fabsf(status.states[14]) > test_limit |
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Remove the original "High Accelerometer Bias" check?
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Reporting the reason for failure if report_fail is true is consistent with the way other test failures are handled.
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Isn't this new "High Accelerometer Bias" check with uncertainty a replacement for the existing "High Accelerometer Bias"? The existing check is still going to trigger, and hence not reduce the number of false positives.
dagar
approved these changes
Feb 4, 2019
bkueng
approved these changes
Feb 4, 2019
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Addresses issue #10833
This PR adjusts the test threshold so that the threshold is scaled up with increasing uncertainty in state estimate. Eventually given sufficient acceleration/rotation all delta velocity bias variances collapse to 5E-8, eg:
which equates to an effective test threshold of 1.73E-3 + 3*sqrt(5E-8) = 2.4E-3 which is the same as the previous threshold and equates to an accel bias of 2.4E-3 / dtEKF = 2.4E-3 / 8E-3 = 0.3 m/s/s
Note that the EKF internally limits the max bias estimate to within an equivalent +-0.4 m/s/s, so we need this check to stay inside that range.
The horizontal axes are poorly observable when on ground and the variances remain high until the vehicle is moved/tilted. In the example shown below the XY axes stay at 100E-8 which would result in a test threshold of (1.73E-3 + 3*sqrt(100E-8)) / 8E-3 = 0.59 m/s/s which would not trigger.
Test data / coverage
Request for testing from affected users in #10833 .