Relaying Fast In-Flight Alignment Method Based on Adaptive Multiconstraints

In-flight alignment is the basis of projectile strapdown inertial navigation system (SINS) accurate navigation. In-flight alignment of guided projectile SINS is faced with "high" complexity, such as satellite interference and random wind disturbance, and "high" dynamics, such as high velocity ( $\ge 500$ m/s), high spin ( $\ge 20$ r/s), and high overload ( $\ge 10$ 000 g). Thus, this article proposes a relaying fast in-flight alignment method based on adaptive multiconstraints, which is mainly divided into the optimization stage and filtering stage. First, the initial attitude angles are taken as the optimization object to establish the optimization model, and the ${K}$ matrix is taken as the state variable to establish the filtering model. Then, the internal relaying mode in the optimization stage and the external relaying mode from the optimization stage to the filtering stage are designed. The rapidity of the optimization algorithm is exerted via adaptive multiconstraint mode to speed up the alignment process. Taking the filtering stage as the main step, the high precision of the filtering algorithm is brought into play to improve alignment accuracy. Simulation and experimental results show that the alignment accuracy and alignment time of this method are better than those of traditional methods.