Strapdown Inertial Navigation Mechanism

Abstract

Strapdown inertial navigation systems are the most common form of inertial navigation system due to its potential benefits of lower cost, reduced size, and greater reliability compared with equivalent gimbal systems. This chapter introduces fundamentals on the strapdown inertial navigation mechanism. In the n‐frame, navigation data are expressed by velocity components along the North, East, and Down directions, and latitude, longitude, and altitude. Therefore, it is more commonly used in navigation applications on the Earth or in the vicinity of the Earth surface. The Coriolis acceleration can be neglected in cases where the navigation error caused by the inertial measurement units (IMU) measurement error is much greater than the Coriolis effect. Attitude initialization, unlike position and velocity initialization, can be achieved by inertial sensors if the IMU is stationary with respect to the Earth. Gyrocompassing requires the IMU to measure the Earth's rotation, which is around 15 °/h, to obtain the yaw angle information.