GNSS (Global Navigation Satellite System)-based constrained EKF (Extend Kalman Filter) relative positioning method

Abstract

The invention discloses a GNSS (Global Navigation Satellite System)-based constrained EKF (Extend Kalman Filter) relative positioning method. According to the method, a conventional measurement modelis constructed by means of pseudo-range measurement and carrier phase measurement; status update and measurement update are performed through using an EKF, so that a high-precision ambiguity floating-point solution is obtained; a partial ambiguity fixing algorithm is used to fix partial ambiguity; a high-precision relative position solution is solved through using the partial ambiguity; with the fixed partial ambiguity vector and the solved high-precision relative position solution used as constraints, an EKF measurement model is reconstructed; EKF secondary status update and measurement update are performed, so that a higher-precision ambiguity floating-point solution can be obtained; and the partial ambiguity fixing algorithm is used again to perform integer ambiguity resolution. With the method adopted, the accuracy of the ambiguity floating-point solution is improved, the rapid fixing of integer ambiguity is accelerated, the initialization time of relative positioning can be shortened, and the real-time performance and reliability of the relative positioning can be enhanced.

Description

technical field [0001] The invention belongs to the technical field of satellite navigation, and more specifically relates to a relative positioning method based on satellite navigation Background technique [0002] Global Navigation Satellite System (GNSS, Global Navigation Satellite System) is a comprehensive system that uses radio signals emitted by artificial earth satellites for navigation. The satellite navigation system that can provide navigation services on a global scale can provide users with global, all-weather, Real-time 3D navigation service. GNSS-based relative positioning is to install two sets of GNSS receivers and antenna equipment on two carriers respectively, receive GNSS measurement information at the same time, and transmit the GNSS measurement information received by one carrier to another carrier in real time through the communication data link. In the computer equipment, the relative position information between the two carriers can be obtained by p...

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Problems solved by technology

[0005] (1) The commonly used method adopts the method of all ambiguities fixed by the LAMBDA method. Due to the different measurement errors of different observation satellites, new satellites are continuously received. The altitude angle of these satellites is relatively low and the noise is relatively large. There is a correlation, and it takes a long time to initialize to fix all the ambiguities; the addition of new satellites will destroy the information of the original ambiguity floating-point solution variance covariance matrix, resulting in the use of the LAMBDA method to fix all ambiguity solutions.

[0006] (2) The commonly used relative positioning method only uses the EKF one-time iteration method, and does not make full use of the precise relative position solution calculated by the partially fixed integer ambiguity and solution. This information reconstructs the measurement model with constraints and strengthens the measurement of the current epoch time model to obtain high-precision ambiguity floating-point solutions, thereby improving the success rate and reliability of all ambiguity fixes

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