Browsing by Author "Ryzhkov, Oleksandr Oleksiyovich"

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    Satellite orientation system using magnetometer and Earth sensor
    (National Aviation University, 2024-07-14) Ryzhkov, Oleksandr Oleksiyovich; Рижков, Олександр Олексійович
    Small spacecraft (SC) are becoming more and more common nowadays. In particular, nanosatellites are used to develop the latest technologies, methods and software and hardware solutions, as well as for educational programs, remote sensing of the Earth and space observations. Due to their small dimensions, weight and cost, as well as a wide range of applications, they have become an integral part of the scientific and space world. Conducting most scientific and applied research in space involves ensuring a certain orientation of the angular position of the nanosatellite in space. To ensure the necessary orientation of the nanosatellite, an orientation system is created, which consists of an algorithm for determining angular values and a regulator that creates a control moment. In this paper, only the algorithm for determining the orientation due to information from the magnetometer and the Earth sensor is considered. Thanks to the use of this pair of sensors, the creation of an orientation system becomes simpler and more reliable. That allows you to be sure that the assigned mission has been solved. Despite the large volume of research, in the created algorithms for determining the orientation of a nanosatellite, as a rule, they are built on the basis of the use of two-vector methods [1, 2], since they are easy to establish and sufficiently reliable. Among such algorithms, the TRIAD algorithm [1], which simultaneously determines three orientation angles, has become more common. But when using the data of the meters, it is not optimal, since the Earth sensor provides information about two angles, and the angle that is in the plane perpendicular to the orbital plane remains unknown. Based on this, there is redundant information. It should also be taken into account that the magnetometer is a less accurate meter than the Earth sensor, which also affects the accuracy of the orientation determination by the TRIAD algorithm. Solving the problem of eliminating redundant information, as well as reducing the influence of a less accurate sensor on the determination of the three orientation angles of a nanosatellite, is an actual direction of research. Solving this issue makes it possible to reduce the load on the on-board computer, as well as to eliminate the cross-influence of the gauges on the orientation accuracy. Which, in turn, will reduce the cost of the finished product due to the use of a weaker calculator, and increase the overall accuracy of determining the angular position. The orientation system of the nanosatellite consists of three main elements, these are the meters of certain physical quantities (orientation sensors), the processing of information sent to the on-board computer (in which the orientation determination algorithm and the control signal generation algorithm are embedded) and the regulator that creates the control moment. The basic quality of determining the angular position of the spacecraft depends on the accuracy of the installed sensors, as well as the orientation algorithm. Determining the orientation of small spacecraft is often accomplished with instruments such as sun sensors and magnetometers. However, these sensors have various disadvantages. For example, solar sensors lose their functionality during periods of solar eclipse in orbit. Magnetometers cannot achieve high accuracy in determining the projection of the intensity of the Earth's magnetic field, due to its constant change. The sensors of the Earth's horizon appeared as an effective and relatively inexpensive meter to ensure accurate determination of the orientation of small spacecraft during low-orbital motion, their accuracy can reach 〖0.1〗^°. Due to the low cost and acceptable accuracy of determining the orientation, the choice was made to use a magnetometer and an Earth sensor as part of the orientation system. We will analyze the existing orientation systems built on the basis of the Earth sensor and magnetometer.