A new approach to improve the stationary fine alignment of the strapdown inertial navigation system
Subject Areas : Electrical engineering (electronics, telecommunications, power, control)
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Keywords: Coarse alignment, Fine alignment, Strapdown Inertial navigation system,
Abstract :
Static alignment, which is one of the important topics in the discussion of inertial navigation, includes two steps of coarse alignment and fine alignment. In coarse alignment, which uses an analytical method, a crude estimate of the initial conditions is obtained, and this estimate is the input to the fine alignment. In fine alignment, a more accurate estimate of the initial conditions is obtained by using a filter and coarse alignment output. One of the things that is addressed in static alignment is the biases of accelerometers and gyroscopes, which cannot be estimated well in traditional methods. In this paper, a new method is proposed to improve the static fine alignment of a strapdown inertial navigation system. In the proposed method, the error state vector of the static fine alignment is divided into two parts: the sensors biases and the position and speed errors. An analytical method has been used to determine sensors biases, and the extended Kalman filter has been used to estimate the position and speed errors. Using simulation, the performance and efficiency of this method have been compared with traditional methods, which shows that the estimation of the initial conditions as well as the sensors biases are done well.
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