Adaptive transfer alignment method based on the observability analysis for airborne pod strapdown inertial navigation system

Abstract

For the airborne pod strapdown inertial navigation system, it is necessary to use the host aircraft's inertial navigation system for the transfer alignment as quickly and accurately as possible in the flight process of the aircraft. The purpose of this paper is to propose an adaptive transfer alignment method based on the observability analysis for the strapdown inertial navigation system, which is able to meet the practical need of maintaining the navigation accuracy of the airborne pod. The observability of each state variable is obtained by observability analysis of system state variables. According to the weight of the observability, a transfer alignment filter algorithm based on adaptive adjustment factor is constructed to reduce the influence of weak observability state variables on the whole filter, which can improve the estimation accuracy of transfer alignment. Simulations and experiment tests of the airborne pod and the master strapdown inertial navigation systems show that the adaptive transfer alignment method based on the observability analysis can overcome the shortage of the weak observability state variables, so as to improve the alignment and the navigation performance in practical applications, thus improving the adaptability of the airborne pod.

Influence of Integration Schemes and Maneuvers on the Initial Alignment and Calibration of AUVs: Observability and Degree of Observability Analyses

“…Regarding b gx and b gz , they can be considered individually observable, as their couplings with b ax , that is, It is also noteworthy that the degree of observability obtained for b gy was close to b gx and significantly higher than b gz . Such results are in agreement with previous works [12,14,15], but raises the question that the degree of observability may not be directly related to the estimation accuracy of the states, given that b gx and b gz are recognizably known to be better estimated than b gy in the AUV initial alignment and calibration problem [23].…”

“…For the lawn mower with zigzag and swing maneuver, the change of orientation in the horizontal plane additionally provoked velocity variations in the NED frame, which produced acceleration components in the north and east directions. The influence of such accelerations on the degree of observability of φ D has also been observed by other authors [12,14,15,27].…”

“…Usual methods to evaluate the observability degree of a state rely on the Q SOM singular value decomposition approach [11,13,15,26]. In particular, the degree of observability can be determined using the weighted singular vector u r [11,26]:…”

“…Concerning the degree of observability, it can be calculated using the degree of independence between the columns (or the singular values) of the observability matrix/Grammian. The singular values, in particular, are largely employed to determine the degree of observability numerically [11][12][13][14][15].…”

One-Step Initial Alignment Algorithm for SINS in the ECI Frame Based on the Inertial Attitude Measurement of the CNS

“…In the field of military applications, concealment is a problem that must be considered [ 25 , 26 ]. In addition, the reference information provided by the master inertial navigation system contains the inherent alignment error and accumulated error, which can also affect the alignment accuracy [ 27 , 28 , 29 ].…”