Which representations are commonly used for vehicle attitude in a 3D EKF?

• A. Quaternion or Euler angles
• B. Latitude-longitude-altitude
• C. Range-bearing-elevation
• D. Speed and heading

Answer: (A)

Attitude means the vehicle’s orientation in three-dimensional space, so you need a rotation representation that can capture roll, pitch, and yaw. Quaternion and Euler-angle representations are the standard ways to encode this in a 3D EKF. Quaternions give a compact, non-singular way to compose rotations and compute the necessary Jacobians for the filter, and they stay robust in updates when you keep them normalized to unit length. Euler angles are intuitive because they map directly to roll, pitch, and yaw, but they can suffer from gimbal lock when pitch gets near ±90 degrees, which is a practical drawback in some EKF implementations.

The other options don’t describe full 3D orientation: latitude-longitude-altitude specifies position, not attitude; range-bearing-elevation describes a direction toward something rather than the vehicle’s own rotation; speed and heading cover velocity and yaw but omit roll and pitch, so they don’t fully define attitude.