Aircraft Attitude Determination using GPS and an Interval Integer Ambiguity Resolution Algorithm (original) (raw)
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An integer ambiguity resolution algorithm for real-time GPS attitude determination
Applied Mathematics and Computation, 2002
The problem of integer ambiguity resolution must be solved to fully exploit the information contained in the GPS carrier phase measurements for real-time attitude determination. A new algorithm for integer ambiguity resolution that uses single-difference smoothed pseudorange measurements is proposed that has several advantages over the conventional algorithms such as the search methods and the motion-based algorithms. These advantages include minimal computational effort at each epoch and an analytically derived equation which calculates the expected time to ambiguity resolution. The validity and the performance of the new algorithm are investigated through simulations although processing real data will be necessary to verify the usability of the proposed algorithm in real situations. Ó (S. Yoon). 0096-3003/02/$ -see front matter Ó 2002 Elsevier Science Inc. All rights reserved. PII: S 0 0 9 6 -3 0 0 3 ( 0 1 ) 0 0 0 2 9 -7
Real time attitude independent GPS integer ambiguity resolution
2003
In this paper, a new motion-based approach for Global Positioning System (GPS) integer ambiguity resolution is derived. The approach first represents the GPS sightline vectors in the body frame or the baseline vectors in the reference frame. The solution to this problem is always available as long as at least three non-coplanar baseline or sightline vectors exist. The body-frame sightline or reference-frame baseline observations are the sum of two vectors, one depending on the phase measurements and the other on the unknown integers. The vector containing the integer phases is identical to the three-axis magnetometer bias model, which can be converted into an attitude independent observation using scalar checking. The bias estimation problem is typically solved by using a batch process. In this paper, simple real time algorithms are developed based on both the extended Kalman filter and Unscented filter. Simulation results indicate that both algorithms provide accurate integer resolution in real time, but the Unscented filter is more robust to large initial condition errors and slow vehicle motions than the extended Kalman filter.
Fast integer ambiguity resolution for GPS attitude determination
Guidance, Navigation, and Control Conference and Exhibit, 1999
In this paper, a new algorithm for GPS integer ambiguity resolution is shown. The algorithm first incorporates an instantaneous (static) integer search to significantly reduce the search space using a geometric inequality. Then a batch-type loss function is used to check the remaining integers in order to determine the optimal integer. This batch function represents the GPS sightline vectors in the body frame as the sum of two vectors, one depending on the phase measurements and the other on the unknown integers. The new algorithm has several advantages: it does not require an a-priori estimate of the vehicle's attitude; it provides an inherent integrity check using a covariance-type expression; and it can resolve the integers even when coplanar baselines exist. The performance of the new algorithm is tested on a dynamic hardware simulator.
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IEEE Transactions on Aerospace and Electronic Systems
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Global Positioning System Integer Ambiguity Resolution Without Attitude Knowledge
Journal of Guidance, Control, and Dynamics, 1999
In this paper, a new motion-based algorithm for GPS integer ambiguity resolution is derived. The algorithm represents the GPS sightline vectors in the body frame as the sum of two vectors, one depending on the phase measurements and the other on the unknown integers. The vector containing the integer phases is found using a procedure developed to solve for magnetometer biases. In addition to a batch solution, this paper also provides a sequential estimate, so that a suitable stopping condition can be found during the vehicle motion. The new algorithm has several advantages: it does not require an apriori estimate of the vehicle's attitude; it provides an inherent integrity check using a covariance-type expression; and it can sequentially estimate the ambiguities during the vehicle motion. Its only disadvantage is that it requires at least three non-coplanar baselines. The performance of the new algorithm is tested on a dynamic hardware simulator.
Attitude determination of GPS satellite vehicles
2016
There is an increasing demand for navigation systems that has led to rapid development of Global Positioning System (GPS) across industries. Apart from position and speed, precise attitude measurements are needed for many GPS applications. This thesis presents techniques for attitude determination of satellite vehicles in both real-time and stand-alone positioning applications. The GPS system used is a differential GPS system that estimates the body frame baselines using at least four receivers. The attitude information is obtained using these baselines and projecting them onto a local level frame. Integer ambiguity is a major constraint in attitude determination. Least Squares Ambiguity Deco-relation method is implemented to fix the ambiguities prior to baseline estimation. Estimation techniques such as Least Squares and Kalman Filter are implemented for deriving baseline components. Finally, this system will compute body frame coordinates and attitude components in reference to th...
GPS Solutions, 2011
Global navigation satellite system (GNSS) ambiguity resolution is the process of resolving the unknown cycle ambiguities of the carrier phase data as integers. The sole purpose of ambiguity resolution is to use the integer ambiguity constraints as a means of improving significantly on the precision of the remaining GNSS model parameters. In this contribution, we consider the problem of ambiguity resolution for GNSS attitude determination. We analyse the performance of a new ambiguity resolution method for GNSS attitude determination. As it will be shown, this method provides a numerically efficient, highly reliable and robust solution of the nonlinearly constrained integer least-squares GNSS compass estimators. The analyses have been done by means of a unique set of extensive experimental tests, using simulated as well as actual GNSS data and using receivers of different manufacturers and type as well as different platforms. The executed field tests cover two static land experiments, one in the Netherlands and one in Australia, and two dynamic experiments, a low-dynamics vessel experiment and high-dynamics aircraft experiment. In our analyses, we focus on stand-alone, unaided, single-frequency, single-epoch attitude determination, as this is the most challenging case of GNSS compass processing.