Tight Integration

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Paul D. Adams - One of the best experts on this subject based on the ideXlab platform.

  • phenix a comprehensive python based system for macromolecular structure solution
    International Tables for Crystallography, 2012
    Co-Authors: Pavel V Afonine, Liwei Hung, Paul D. Adams, Ian W Davis, Nathaniel Echols, Jeffrey J Headd, Gabo Unkoczi, Vince Che, Gary J Kapral
    Abstract:

    Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. However, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallographic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a Tight Integration between the algorithms. Keywords: PHENIX; Python; algorithms

  • phenix a comprehensive python based system for macromolecular structure solution
    Acta Crystallographica Section D-biological Crystallography, 2010
    Co-Authors: Gabor Bunkoczi, Pavel V Afonine, Vincent B Chen, Liwei Hung, Paul D. Adams, Ian W Davis, Nathaniel Echols, Jeffrey J Headd, Gary J Kapral
    Abstract:

    Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. How­ever, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallo­graphic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a Tight Integration between the algorithms.

Xiyuan Chen - One of the best experts on this subject based on the ideXlab platform.

  • a novel linear model based on code approximation for gnss ins ultra Tight Integration system
    Sensors, 2020
    Co-Authors: Zhe Yan, Xiyuan Chen, Xinhua Tang
    Abstract:

    The superiority of a global navigation satellite system (GNSS)/inertial navigation system (INS) ultra-Tight Integration navigation system has been widely verified. For those systems with centralized structure based on coherent-accumulation measurements (I/Q), the conversion from I/Q signals to navigation information is implemented by an observation equation. As a result, the model is highly complex and nonlinear, exerting essential influence on system performance. Based on the analysis of previous studies, a novel model and its linearization method are proposed, aiming at the integrity, stability and implicit nonlinear factors. Unlike the one-order precision in the common Jacobian matrix, two-order components are partly reserved in this model, which makes it possible for higher positioning accuracy and better convergence. For the positioning errors caused by ignoring code-loop deviation, a method to approximate code-phase is proposed without introducing new measurements. Consequently, the effect of code error can be significantly reduced, especially when the tracking loops are unstable. In the end, using real-sampled satellite signals, semi-physical experiments are carried out and the effectiveness and superiority of new methods are proved.

  • theoretical analysis and application of kalman filters for ultra Tight global position system inertial navigation system Integration
    Transactions of the Institute of Measurement and Control, 2012
    Co-Authors: Xiyuan Chen, Xuefen Zhu
    Abstract:

    When a global position system (GPS) is combined with an inertial navigation system (INS) in the ultra-Tight GPS/INS integrated navigation system, their performances are both optimized. However, different from loose and Tight Integration, in the ultra-Tight Integration, the non-linearity of Kalman measurements will seriously affect the filtering result. As the performance of the Kalman filter is radically affected by the modelling strategies, this paper will discuss it in depth. Firstly, the modelling of a traditional Kalman filter for ultra-Tight Integration is introduced by derivation and simulation experiments based on a single-frequency GPS software receiver. Then, the theoretical analysis of its performances on observability, controllability and stability is given. According to that, a novel extended Kalman filter for the ultra-Tight Integration is presented, using a Q (quadrature) signal from the GPS receiver correlator and a position and velocity from both the GPS and INS to form the measurements of...

  • application of extended kalman filter in ultra Tight gps ins Integration based on gps software receiver
    International Conference on Green Circuits and Systems, 2010
    Co-Authors: Xiyuan Chen
    Abstract:

    When designing the ultra-Tight GPS/INS Integration, the architecture of Kalman filter is the key to its successful performance; the crux of this architecture is the measurement model. Aiming at the dependence of numbers of tracked GPS satellites and poor noise immunity in loose and Tight Integration modes, this paper proposes a new method of ultra-Tight Integration, using the Q(quadrature) signal from the GPS receiver correlator, receiver position and velocity to form the measurements of the extended Kalman filter. The experiments are carried out based on semi-physics, using the factual data solved by GPS software receiver, and the results show good performance.

Gary J Kapral - One of the best experts on this subject based on the ideXlab platform.

  • phenix a comprehensive python based system for macromolecular structure solution
    International Tables for Crystallography, 2012
    Co-Authors: Pavel V Afonine, Liwei Hung, Paul D. Adams, Ian W Davis, Nathaniel Echols, Jeffrey J Headd, Gabo Unkoczi, Vince Che, Gary J Kapral
    Abstract:

    Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. However, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallographic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a Tight Integration between the algorithms. Keywords: PHENIX; Python; algorithms

  • phenix a comprehensive python based system for macromolecular structure solution
    Acta Crystallographica Section D-biological Crystallography, 2010
    Co-Authors: Gabor Bunkoczi, Pavel V Afonine, Vincent B Chen, Liwei Hung, Paul D. Adams, Ian W Davis, Nathaniel Echols, Jeffrey J Headd, Gary J Kapral
    Abstract:

    Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. How­ever, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallo­graphic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a Tight Integration between the algorithms.

Yongquan Zhu - One of the best experts on this subject based on the ideXlab platform.

  • A study on GPS integrity monitoring algorithms based on ultra-Tight Integration system
    2011 6th IEEE Conference on Industrial Electronics and Applications, 2011
    Co-Authors: Yongquan Zhu
    Abstract:

    The Global Positioning System (GPS), Inertial Navigation System (INS) technologies both play very important roles in navigation systems. Ultra-Tight Integration offers numerous advantages including increased robustness under high dynamics, and improved anti-jamming performance. It can be applied to integrity monitoring, which is an elementary performance of flying security in the field of aeronautics and astronautics. This paper introduces an integrity monitoring algorithm based on ultra-Tight configuration. The ultra-Tight configuration is realized by the way of INS-aided GPS tracking loops. With the information from INS, the tracking performance can be improved since the tracking loop parameters can be optimized beyond the GPS-only case. The test statistics is given by the Kalman filter residual based on the ultra-Tight filter. A rate detector configuration is used in integrity monitoring process based on the ultra-Tight configuration. In the end of this paper, the simulated high dynamic flight test results of ultra-Tight Integration based on the Kalman filter are presented, and the results showed that this algorithm can get better performance in integrity monitoring.

Xinhua Tang - One of the best experts on this subject based on the ideXlab platform.

  • a novel linear model based on code approximation for gnss ins ultra Tight Integration system
    Sensors, 2020
    Co-Authors: Zhe Yan, Xiyuan Chen, Xinhua Tang
    Abstract:

    The superiority of a global navigation satellite system (GNSS)/inertial navigation system (INS) ultra-Tight Integration navigation system has been widely verified. For those systems with centralized structure based on coherent-accumulation measurements (I/Q), the conversion from I/Q signals to navigation information is implemented by an observation equation. As a result, the model is highly complex and nonlinear, exerting essential influence on system performance. Based on the analysis of previous studies, a novel model and its linearization method are proposed, aiming at the integrity, stability and implicit nonlinear factors. Unlike the one-order precision in the common Jacobian matrix, two-order components are partly reserved in this model, which makes it possible for higher positioning accuracy and better convergence. For the positioning errors caused by ignoring code-loop deviation, a method to approximate code-phase is proposed without introducing new measurements. Consequently, the effect of code error can be significantly reduced, especially when the tracking loops are unstable. In the end, using real-sampled satellite signals, semi-physical experiments are carried out and the effectiveness and superiority of new methods are proved.