Robotics - General ESKF Hands-on Test Notes - Rico贾若童的博客

Primers

Did you turn on the message debugging flag, or are you compiling with PRINT_DEBUG_MSGS?
Are you sure you are launching the right test?

Velocity drift observed. Here, I’m proposing a two-phase static test to confirm true sensor drift:

Initialization—standstill for N seconds to estimate biases.
Static logging—remain stationary and record velocity.
If velocity continues to grow, it’s genuine drift.
Initial results show the same drift pattern—next step is to connect directly to the IMU board (bypass middleware) to rule out software filtering or fusion artifacts.

I observed that angular rate remains stable over the static test; no significant gyro drift detected.

Accelerometer bias

Sampling at 33 Hz, the mean linear-acceleration bias is ≈ 0.3 m/s² (≈ 0.03 g).
- Projected drift: ~560 m over one minute—still within typical MEMS accelerometer error bounds.
- Changing the static initialization window shifts the estimated accelerometer bias (ba) and gyro bias (bg), which alters the trajectory shape but does not eliminate the drift or induced rotation.
Bias characteristics
- IMU biases are not fixed constants. They:
  - Drift with temperature.
  - Exhibit bias-random-walk (BRW) that grows proportionally to √t.
  - Often follow a 1/f noise spectrum rather than pure white noise.
- Tactical in-run bias stability is on the order of micro-g, but bias repeatability is typically larger—see Advanced Navigation’s IMU introduction for details.

When GPS heading is invalid, are you omitting GPS messages?
- One may choose not to omit GPS. We could just set their ESKF jacobians to 0.
GPS needs IMU to be initialized
IMU integration needs the first GPS to be found

Do you get messages exactly the same timing?
Are data synchronization, like the GPS and IMU Data sync correct?
When GPS starts becoming valid, do you choose the pose there to be your initial pose?
- Initial velocity is from the IMU. They are not directly corrected by GPS. So wrong initial velocity could make IMU spin a lot while its cartesian pose is around the GPS point