Initial alignment method for micro electro mechanical system (MEMS) strap-down inertial navigation adaptive square-root cubature Kalman filtering (SCKF)

The invention discloses an initial alignment method for micro electro mechanical system (MEMS) strap-down inertial navigation adaptive square-root cubature Kalman filtering (SCKF). The method comprises the following steps: determining initial position information of a carrier through a global positioning system (GPS), acquiring data which is output by an MEMS accelerometer and a magnetometer, and completing coarse alignment through an analytical method to roughly obtain a strap-down matrix; establishing a nonlinear model which is initially aligned by an MEMS-based strap-down inertial navigation system, and performing filtering initialization; performing state estimation through SCKF, and updating a system noise variance matrix according to the difference between state estimation quantity and one-time prediction state quantity during iteration at each time to improve filtering adaptive capability to indeterminacy of system noise statistical characteristics; and acquiring an attitude matrix of an accurate platform misalignment angle correction system so as to complete initial alignment. According to the initial alignment method, the initial alignment can be well completed when the constant drift of a gyroscope is large, and the filtering adaptive capability to the indeterminacy of the system noise statistical characteristics is improved.