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Abstract

Conventionally, the filtering technique for attitude estimation is performed using gyros or attitude dynamics models. In order to extend the application range of an attitude filter, this paper proposes a quaternionbased filtering framework for gyroless attitude estimation without an attitude dynamics model. The attitude estimation system is established based on a quaternion kinematic equation and vector observation models. The angular velocity in the system is determined through observation vectors from attitude sensors and the statistical properties of the angular velocity error are analysed. A Kalman filter is applied to estimate the attitude error such that the effect from the angular velocity error is compensated with its statistical properties at each sampling moment. A numerical simulation example is presented to illustrate the performance of the proposed algorithm.
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Abstract

The changes in the paralinguistic (social, economic, cultural) and linguistic sphere influence the quantitative and qualitative changes in a categorically diversified onomastic resource and the communicative flow of its elements on three levels of linguistic contact — nationwide, local and individual. The flow is additionally determined in the sphere of spontaneous everyday communication and in higher communicative functions (official linguistic behaviour). The accumulation of determinants which allow the usage of appropriate names and appellative forms (official and unofficial, e.g. diminutives, feminisms) involves the application of cumulative research methods, including psycho-, socio- and pragmalinguistic description of proper names functioning in communication. The contemporary theory of discourse in its three dimensions — formal, functional and interactional gives this possibility. It also requires the constant specification and standardization of Neoslavonic onomastic terminology.
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Abstract

Single-frame methods of determining the attitude of a nanosatellite are compared in this study. The methods selected for comparison are: Single Value Decomposition (SVD), q method, Quaternion ESTimator (QUEST), Fast Optimal Attitude Matrix (FOAM) − all solving optimally the Wahba’s problem, and the algebraic method using only two vector measurements. For proper comparison, two sensors are chosen for the vector observations on-board: magnetometer and Sun sensors. Covariance results obtained as a result of using those methods have a critical importance for a non-traditional attitude estimation approach; therefore, the variance calculations are also presented. The examined methods are compared with respect to their root mean square (RMS) error and variance results. Also, some recommendations are given.
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