Which combination is typically used by an IMU for orientation estimation?

• A. Accelerometer, Gyro, and Magnetometer.
• B. GPS, Barometer, and Thermometer.
• C. Cameras and LiDAR.
• D. Touch sensors only.

Answer: (A)

Orientation estimation with an IMU relies on fusing data from sensors that measure motion and magnetic direction. An IMU typically includes a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. The gyroscope provides angular velocity, and integrating it over time tracks how the orientation is changing, but this integration drifts due to bias and noise. The accelerometer measures acceleration that includes gravity, which helps determine tilt relative to the vertical when motion is not dominating, while the magnetometer provides a heading reference by sensing the Earth's magnetic field. By combining these signals through sensor fusion (like a Kalman or complementary filter), you obtain a stable estimate of orientation. The other sensor groups (GPS with barometer and thermometer, cameras with LiDAR, or touch sensors) either measure position/environment or are not used by the IMU itself to infer orientation, so they’re not typical for this purpose. Therefore, accelerometer, gyro, and magnetometer is the standard combination for orientation estimation.