What is the effect of misalignment between INS sensors and the body frame?

• A. Only affects velocity measurement.
• B. Causes systematic attitude and position errors; calibration or including misalignment as a fixed parameter in the state can mitigate it.
• C. Increases GPS saturation.
• D. Eliminates need for calibration.

Answer: (B)

Misalignment between the INS body frame and the sensor frames acts like a small fixed rotation error that shows up in all navigation estimates. Since the IMU outputs angular rates and specific forces in its own sensor frame, any misalignment between that frame and the vehicle’s body frame means those measurements are rotated relative to the true body axes. That rotation transfers into attitude estimates, and those attitude errors then propagate into velocity and, over time, into position errors. The practical fix is to calibrate the misalignment or include it as a fixed parameter in the navigation state so the estimator can learn and compensate for it. This is why the correct understanding is that the misalignment causes systematic attitude and position errors and can be mitigated by calibration or by estimating the misalignment in the state. It doesn’t directly cause GPS saturation, and it does not remove the need for calibration.