IMU tools
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.
- IMU biases are not fixed constants. They:
