Abstract
The integrated navigation method based on star sensor celestial angles (altitude angle and azimuth angle) is proposed to serve the need for rapidly responsive, reliable, and precise of a hypersonic vehicle under a sophisticated environment. An integrated navigation algorithm suitable for large azimuth misalignment is established under launching point inertial coordinate and local geographical coordinate system based on altitude angle and azimuth angles. Meanwhile, a Bayesian method for data dropouts aided by the strapdown celestial angles is presented for the rapid variability in the celestial star angle with active galaxies. A nonlinear Bayesian filter is applied to implement the simulation on account of the nonlinear feature of the state and measurement equations. The simulation results showed that the Bayesian method for integrated navigation data dropouts could be accomplished by altitude angle and azimuth angle aiding in both launching point inertial coordinate and local geographical coordinate systems, which converge to 1′ in 10 s. The method indicated that the integrated navigation significant errors derived from initial localization and initial attitude alignment could be modified by the strapdown inertial navigation system (SINS) supported by the star sensor’s celestial angle in the local geographic coordinate system in the early launch stage. For the seconds of the flight phase, the integrated navigation aided by celestial angles in the launching point inertial coordinate system was guaranteed for the feasibility and validity. During the flight, the feasibility and validity of integrated navigation were guaranteed aided by celestial angles in launching point inertial coordinate system.
Highlights
Due to the long-term flight of the vehicle in the adjacent space during a long-distance trip, it has unique characteristics in the aerospace field, and the adjoining area has become a hot spot in the world.[1]
The navigation system model under launching point inertial coordinate and local geographical coordinate can be obtained according to mathematical platform misalignment angle error equations, velocity, position error equations, and the process noise of propagation caused by those gyro from bs to bh, and Cibm is the attitude matrix of the master and accelerator stochastic drift
According to the steps (1) and (2), the integrated navigation measurement model based on the star sensor is matched by altitude angle and the azimuth angle dh 1⁄4 H pb À H obl þ vh; da 1⁄4 Apb À Aobl þ va ð24Þ
Summary
Due to the long-term flight of the vehicle in the adjacent space during a long-distance trip, it has unique characteristics in the aerospace field, and the adjoining area has become a hot spot in the world.[1]. The navigation system model under launching point inertial coordinate and local geographical coordinate can be obtained according to mathematical platform misalignment angle error equations, velocity, position error equations, and the process noise of propagation caused by those gyro from bs to bh, and Cibm is the attitude matrix of the master and accelerator stochastic drift. According to the steps (1) and (2), the integrated navigation measurement model based on the star sensor is matched by altitude angle and the azimuth angle dh 1⁄4 H pb À H obl þ vh; da 1⁄4 Apb À Aobl þ va ð24Þ the altitude angle (Hotl) and azimuth (Aotl) in the compensated geographic coordinate system are obtained as. The observation is the difference between the slaver navigation solution of altitude/azimuth angles and those celestial angles of vehicle-mounted star sensor, which gives a detailed equation dh 1⁄4 H n^b À H b; da 1⁄4 An^b À Ab ð38Þ. The setting of the Bayesian sequence involves the predictions of the state and the noise on the Chapman–Kolmogorov formula[23] f
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