An in-motion initial alignment method aided by digital map

The traditional in-motion initial alignment method obtains the gravity vector in inertial coordinate system twice while parking the land vehicle, and then work out the transformation matrix according to the information obtained. This method sets a limit to the speed and route of vehicle and requires high precision in positioning of coarse alignment. In this work, digital map is introduced into the in-motion alignment. With the aid of map matching algorithm, the positioning accuracy is greatly improved in all speeds and routes, which reduces the effect of misalignment angle from coarse alignment for positioning error and improves the accuracy of the in-motion initial alignment. Road tests results show that the integration of digital map and RLG SINS eliminates the requirements of speeds and routes for land vehicles and greatly reduces the effect of coarse alignment for azimuth accuracy. It not only enhances the mobility of land vehicle but also improves the accuracy of initial alignment of inertial navigation system, which is meaningful in real application.