scholarly journals A Fault-Tolerant Level Damping Algorithm for Marine INS

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guohu Feng
Keyword(s):  
Fault Tolerant ◽  
Velocity Oscillation ◽  
Navigation Solution ◽  
Reference Velocity ◽  
External Reference ◽  
Variable Damping ◽  
Velocity Changes ◽  
Navigation Test ◽  
Navigation Accuracy ◽  
Damping Model

When the measurement error of the external reference velocity changes dramatically, the traditional level damping for marine INS needs to cut off the damping to maintain the navigation accuracy. The level channel has a large overshoot oscillation during the variable damping instantaneous, which results in obvious position deviation. In order to solve this practical problem, a damping model is established outside the INS. The most obvious advantage of the algorithm is that the damping algorithm does not affect the inertial navigation solution. The fault-tolerant algorithm realizes the automatic damping switch according to the external reference velocity error variation criterion, which avoids the velocity oscillation and position deviation. Compared with traditional methods, the algorithm presented in this paper has higher reliability and better environmental adaptability. The effectiveness of the algorithm is verified by the actual navigation test data.

scholarly journals Design of Variable Damping INS for Ships Based on the Variation of Reference Velocity Error

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chuang Liu ◽  
Qiuping Wu ◽  
Peida Hu ◽  
Rong Zhang
Keyword(s):  
Fuzzy Controller ◽  
Navigation Systems ◽  
Inertial Navigation Systems ◽  
Velocity Error ◽  
Reference Velocity ◽  
Frequent Switching ◽  
Variable Damping ◽  
Oscillation Damping ◽  
Navigation Accuracy

Schuler oscillation damping is one of the key technologies to improve the long-term precision of inertial navigation systems (INSs). Generally, a ship introduces the reference velocity to work on the external horizontal damping status to avoid the effects caused by maneuvers. However, the navigation accuracy is sensitive to the reference velocity error which will be affected by sea conditions and the ship’s maneuver. It is necessary to adjust the damping status dynamically as the change of the reference velocity error to ensure the accuracy and stability of INS. To address this problem, a novel variable damping system based on the variation of the reference velocity error is designed in this paper. First of all, this proposed method switched the damping status according to the variation of the reference velocity error in a certain period of time based on the principle of window detection. In addition, this paper designed a fuzzy controller to avoid the overshoot caused by the frequent switching of the damping status. What is more, a method of overshoot suppression was applied in this system. Simulation experiments were conducted to validate the theoretical analysis and the effectiveness of this method. Compared with the undamping system, constant damping system, and traditional variable damping system, the simulation results verified that the designed variable damping system can attenuate the system error caused by reference velocity error most effectively, thus improving the navigation accuracy of INS.

scholarly journals A SINS/BDS Integrated Navigation Method Based on Classified Weighted Adaptive Filtering

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Xuchao Kang ◽  
Guangjun He ◽  
Xingge Li
Keyword(s):  
Adaptive Filtering ◽  
Navigation System ◽  
Fault Tolerant ◽  
Hypothesis Test ◽  
Integrated Navigation ◽  
Integrated Navigation System ◽  
Covariance Matching ◽  
Uncertain Model ◽  
Navigation Accuracy ◽  
Navigation Method

Aiming at the problem that the accuracy and stability of SINS/BDS integrated navigation system decrease due to uncertain model and observation anomalies, a SINS/BDS integrated navigation method based on classified weighted adaptive filtering is proposed. Firstly, the innovation covariance matching technology is used to detect whether there is any abnormality in the system as a whole. Then the types of anomalies are distinguished by hypothesis test. Different types of anomalies have different effects on state estimation. Based on the dynamic changes of innovation, different adaptive weighting methods are adopted to correct navigation information. The simulation results show that this method can effectively improve the fault-tolerant performance of integrated navigation system in complex environment with unknown anomaly types. When both model anomalies and observation anomalies exist, the speed and position accuracy are increased by 42% and 24% compared with the standard KF, 38% and 22% compared with the innovation orthogonal adaptive filtering, which has higher navigation accuracy.

scholarly journals Results of the GNSS receiver experiment OCAM-G on Ariane-5 flight VA 219

2016 ◽  
Vol 231 (6) ◽  
pp. 1100-1114 ◽  
Author(s):  
André Hauschild ◽  
Markus Markgraf ◽  
Oliver Montenbruck ◽  
Horst Pfeuffer ◽  
Elie Dawidowicz ◽  
...  
Keyword(s):  
French Guiana ◽  
Satellite System ◽  
Navigation Satellite ◽  
Navigation Solution ◽  
Gnss Receiver ◽  
Upper Stage ◽  
Lift Off ◽  
Global Navigation Satellite ◽  
Navigation Accuracy ◽  
First Time

The fifth Automated Transfer Vehicle was launched on 29 July 2014 with Ariane-5 flight VA 219 into orbit from Kourou, French Guiana. For the first time, the ascent of an Ariane rocket was independently tracked with a Global Navigation Satellite System (GNSS) receiver on this flight. The GNSS receiver experiment OCAM-G was mounted on the upper stage of the rocket. Its receivers tracked the trajectory of the Ariane-5 from lift-off until after the separation of the Automated Transfer Vehicle. This article introduces the design of the experiment and presents an analysis of the data gathered during the flight with respect to the GNSS tracking status, availability of navigation solution, and navigation accuracy.

scholarly journals An Automated 2D Multipass Doppler Radar Velocity Dealiasing Scheme

2006 ◽  
Vol 23 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
Jian Zhang ◽  
Shunxin Wang
Keyword(s):  
Doppler Radar ◽  
Radar Data ◽  
Velocity Fields ◽  
Velocity Data ◽  
Computationally Efficient ◽  
High Confidence ◽  
Reference Velocity ◽  
External Reference ◽  
Wind Velocities ◽  
Radar Velocity

Abstract An automated 2D multipass velocity dealiasing scheme has been developed to correct velocity fields when wind velocities are very large compared to the Nyquist velocity of the weather Doppler radars. The new velocity dealiasing algorithm is based on the horizontal continuity of velocity fields. The algorithm first determines a set of reference radials and gates by finding the weakest wind region. Then from these reference radials and gates, the scheme checks continuities among adjacent gates and corrects for the velocity values with large differences that are close to 2 × (Nyquist velocity). Multiple passes of unfolding are performed and velocities identified as “folded” with low confidence in an earlier pass are not unfolded until a discontinuity is detected with high confidence at a subsequent pass. The new velocity dealiasing scheme does not need external reference velocity data as do many existing algorithms, thus making it more easily applicable. Over 1000 radar volume scans that include tornadoes, hurricanes, and typhoons are selected to test and to evaluate the new algorithm. The results show that the new algorithm is very robust and very computationally efficient. In cases with many data voids, the new algorithm shows improvements over the current WSR-88D operational velocity dealiasing scheme. The new dealiasing algorithm is a simple and stand-alone program that can be a very useful tool to various Doppler radar data users.

New fault-tolerant federated Kalman filters for integrated navigation

2018 ◽  
Vol 90 (1) ◽  
pp. 65-73
Author(s):  
Yueqian Liang ◽  
Yingmin Jia
Keyword(s):  
Kalman Filter ◽  
Kalman Filters ◽  
Fault Tolerant ◽  
Distribution Coefficients ◽  
Integrated Navigation ◽  
Content Type ◽  
Vector Distribution ◽  
Federated Kalman Filter ◽  
Aerial Vehicle ◽  
Navigation Accuracy

Purpose The purpose of this paper is to achieve accurate integrated navigation results for the unmanned aerial vehicle (UAV) systems even in the presence of possible navigation faults in the subsystems of the federated Kalman filter. Design/methodology/approach The federated Kalman filter is modified from two aspects to get accurate navigation results under abnormity. First, time-variant vector distribution coefficients trading off the navigation accuracy and the observability degree of each state component are computed to replace the traditional scalar coefficients. Second, a fault-tolerant filter is proposed as the local navigation filter. Findings Simulations for the navigation of a UAV system show that the proposed method can be applied for accurate navigation purpose even in the presence of subsystem navigation faults. Originality/value New fault-tolerant federated Kalman filters for integrated navigation are presented to achieve accurate navigation solutions.

A Study on a Controller to Suppress Periodic Speed Variation

2003 ◽  
Vol 22 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Manabu Kosaka ◽  
Hiroshi Uda ◽  
Eiichi Bamba
Keyword(s):  
Energy Consumption ◽  
Repetitive Control ◽  
Sine Wave ◽  
Motor Speed ◽  
Angle Sensor ◽  
Tuning Parameters ◽  
Speed Variation ◽  
Reference Velocity ◽  
Velocity Changes ◽  
Increase Energy Consumption

This paper is concerned with a practical controller to suppress the periodic speed variation of a motor. Speed variation in a pump, a compressor or a wheel of an electric vehicle causes vibration and noise, which shorten the life of the machine. Although repetitive control can suppress the speed variation, there are the following problems: If a reference velocity changes, the period of the speed variation changes and the effect of the suppression is reduced. The tuning parameters are difficult to tune. In the case where a low-resolution angle sensor is used, the output of the controller to suppress the speed variation becomes pulse-shaped and causes harmonic ripples that increase energy consumption. In order to eliminate the harmonic ripples, we propose a controller of which the output is interpolated with a sine wave.

scholarly journals UNRAVEL: A Robust Modular Velocity Dealiasing Technique for Doppler Radar

2020 ◽  
Vol 37 (5) ◽  
pp. 741-758
Author(s):  
Valentin Louf ◽  
Alain Protat ◽  
Robert C. Jackson ◽  
Scott M. Collis ◽  
Jonathan Helmus
Keyword(s):  
Modular Design ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Reference Points ◽  
Weather Data ◽  
Doppler Velocity ◽  
Weather Radars ◽  
Reference Velocity ◽  
External Reference ◽  
Radar Velocity

AbstractUnfold Radar Velocity (UNRAVEL) is an open-source modular Doppler velocity dealiasing algorithm for weather radars. UNRAVEL is an algorithm that does not need external reference velocity data, making it easily applicable. The proposed algorithm includes 11 core modules and 2 dealiasing strategies. UNRAVEL is an iterative algorithm. The goal is to build the dealiasing results starting with the strictest possible continuity tests in azimuth and range and, after each step, relaxing the parameters to include more results from a progressively growing number of reference points. UNRAVEL also has modules that perform 3D continuity checks. Thanks to this modular design, the number of dealiasing strategies can be expanded in order to optimize the dealiasing results. While the first driver dealiases Doppler velocity from each tilt independently from one another, the second driver also performs a three-dimensional continuity check of the velocity using successive elevations. The proposed dealiasing algorithm is tested using severe weather data from an S-band Doppler radar that have been aliased to mimic aliased radial velocity patterns that would be observed by a C-band Doppler radar. Artificially aliasing S-band data permits creation of a reference to which the performance of various dealiasing techniques can be compared. Comparisons show that UNRAVEL consistently outperforms other established dealiasing algorithms for the test period selected in this work.

Optimising the Integration of Terrain Referenced Navigation with INS and GPS

2005 ◽  
Vol 59 (1) ◽  
pp. 71-89 ◽  
Author(s):  
Paul D Groves ◽  
Robin J Handley ◽  
Andrew R Runnalls
Keyword(s):  
Gaussian Mixture ◽  
Gps Data ◽  
Low Grade ◽  
Radar Altimeter ◽  
Processing Efficiency ◽  
Navigation Solution ◽  
Gps Navigation ◽  
Terrain Referenced Navigation ◽  
Simulation Results ◽  
Navigation Accuracy

The benefits of integrated INS/GPS systems are well known. However, the knowledge required to jam GPS is becoming public and the hardware to achieve this is basic. When GPS data are unavailable and a low grade INS is used, navigation accuracy quickly degrades to an unacceptable level. The addition of one or more terrain referenced navigation (TRN) systems to an integrated INS/GPS navigation system enables the INS to be calibrated during GPS outages, increasing the robustness of the overall navigation solution. TRN techniques are compared and integration architectures are reviewed. For the initial studies of INS/GPS/TRN integration, radar altimeter based terrain contour navigation (TCN) with a batch processing algorithm is used in conjunction with a centralised integration filter. Four different approaches for using these TCN fixes to calibrate the INS are compared. These are a best fix method, a weighted fix method using a probabilistic data association filter (PDAF) and single and multi-hypothesis versions of the Iterative Gaussian Mixture Approximation of the Posterior (IGMAP) method. Simulation results are presented showing that the single hypothesis IGMAP technique offers the best balance between accuracy, robustness and processing efficiency.

100 KV Scanning Microscope

1972 ◽  
Vol 30 ◽  
pp. 472-473 ◽  
Author(s):  
A. V. Crewe ◽  
M. W. Retsky
Keyword(s):  
High Voltage ◽  
Voltage Divider ◽  
Electron Gun ◽  
Objective Lens ◽  
Parallel Beam ◽  
Emission Point ◽  
Error Amplifier ◽  
External Reference ◽  
Scanning Transmission ◽  
Transmission Microscope

A 100 kv scanning transmission microscope has been built. Briefly, the design is as follows: The electron gun consists of a field emission point and a 3 cm Butler gun. The beam has a crossover outside the gun and is collimated by a condenser lens.The parallel beam passes through a defining aperture and is focused by the objective lens onto the specimen. The elastic electrons are detected by two annular detectors, each subtending a different angle, and the unscattered and inelastic electrons are collected by a third detector. The spectrometer that will separate the inelastic and unscattered electrons has not yet been built.The lens current supplies are stable to within one part per million per hour and have been described elsewhere.The high voltage is also stable to 1 ppm/hr. It consists of the raw supply from a 100 kv Spellman power supply controlled by an external reference voltage, high voltage divider, and error amplifier.

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