The main purpose of navigation systems is position determination for different types of moving objects. To start their operation, the onboard standard navigation algorithms requires initial data such as data about the position (latitude, longitude, and altitude). Currently exists different solutions for position determination, the main of them relates to astronomical methods or refers to using satellite or radio signals. But, astronomical methods highly depend on climate conditions, and satellite or radio signals can be unavailable for usage, or even can be intentionally jammed in military applications. Thus, the development of autonomous methods for position determination without using external aiding data is an actual task.
The article proposes the autonomous method of the initial latitude determination utilizing an inertial measurement unit (IMU) and a navigation computer. IMU should be equipped with inertial sensors (orthogonal placed three accelerometers and three gyroscopes) and a signal processing circuit. Where gyroscopes allow measuring projections of Earth's angular velocity on the IMU axes and accelerometers allow measuring projections of the gravity acceleration on the IMU axes.
The efficiency of the proposed method confirmed through the tests with highly accurate sensors such as a triad of ring laser gyroscopes and pendulum accelerometers. In addition, the effects of varios base attitude on the accuracy of the system were considered. Where was obtained latitude variations in different body inclines.
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