scholarly journals GPS based onboard orbit determination system providing fault management features for a LEO satellite

2013 ◽  
Vol 66 (4) ◽  
pp. 539-559 ◽  
Author(s):  
H. Bolandi ◽  
M. H. Ashtari Larki ◽  
M. Abedi ◽  
M. Esmailzade
Keyword(s):  
Orbit Determination ◽  
Equations Of Motion ◽  
Fault Management ◽  
Time Intervals ◽  
Earth Gravity ◽  
Earth Gravity Model ◽  
Determination Process ◽  
Position Data ◽  
Determination System ◽  
Leo Satellite

This paper presents accurate orbit determination (OD) of the Iran University of Science and Technology Satellite (IUSTSAT) from Global Positioning System (GPS) data. The GPS position data are treated as pseudo-measurements within an onboard orbit determination process that is based on the numerical integration of the equations of motion using an earth gravity model and applying an Extended Kalman Filter for the data processing. In this paper, through accurate tuning of GPS duty cycle and on/off time intervals, a solution is suggested to achieve the desired OD accuracy despite power constraints. Moreover, a new scheme for automatic fault management in the orbit determination system is derived that provides fault detection and accommodation features.

scholarly journals Sensitivity of the Gravity Model and Orbital Frame for On-board Real-Time Orbit Determination: Operational Results of GPS-12 GPS Receiver

2019 ◽  
Vol 11 (13) ◽  
pp. 1542
Author(s):  
Eunhyouek Kim ◽  
Seungyeop Han ◽  
Amer Mohammad Al Sayegh
Keyword(s):  
Real Time ◽  
Gravity Model ◽  
Orbit Determination ◽  
Low Earth Orbit ◽  
Observation Data ◽  
Gps Receiver ◽  
Champ Satellite ◽  
Earth Gravity ◽  
Earth Gravity Model ◽  
Gravity Recovery

This paper describes the sensitivity of both the orbital frame domain selection and the gravity model on the performance of on-board real-time orbit determination. Practical error sources, which affect the navigation solution of spaceborne global positioning system (GPS) receivers, are analyzed first. Then, a reasonable orbital frame (radial, in-track, cross-track (RIC)) is proposed to clearly represent the characteristics of the error in order to improve the performance of the orbit determination (OD) logic. In addition, the sensitivity of the gravity model affecting the orbit determination logic is analyzed by comparison with the precise orbit ephemeris (POE) of the Challenging Minisatellite Payload (CHAMP) satellite, and it is confirmed that the Gravity Recovery And Climate Experiment (GRACE) Gravity Model 03 (GGM03) outperforms the Earth Gravity Model 1996 (EGM96). The effects of both proposed orbit frames and the gravity model on the orbit determination logic are verified using a GPS simulator and observation data from the CHAMP satellite. Moreover, the practical performance of on-board real-time orbit determination logic is verified by updating the software of the spaceborne GPS receiver, GPS-12, on DubaiSat-2 operating at low Earth orbit (LEO). The results show that the position accuracy of on-board real-time orbit determination logic in GPS-12 is improved by 59%, from 12.6 m (1 σ) to 5.1 m (1 σ), after applying the proposed methods. The velocity accuracy is also improved by 57%, from 13.7 mm/s (1 σ) to 5.9 mm/s (1 σ).

Precise LEO satellite orbit determination and Earth gravity field modeling with carrier-range method

2020 ◽  
Author(s):  
Geng Gao ◽  
Xiancai Zou ◽  
Shoujian Zhang ◽  
Bingshi Liu
Keyword(s):  
Gravity Field ◽  
Field Model ◽  
Satellite Orbit ◽  
Gravity Field Model ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
Field Modeling ◽  
Earth Gravity Model ◽  
Gravity Field Modeling ◽  
Leo Satellite

<p>Precise LEO satellite orbit determination(OD) and Earth gravity field modeling are researched in this study.</p><p>Firstly, on the basis of Precise Point Positioning Ambiguity Resolution(PPPAR), a kinematic LEO satellite OD algorithm based on the epoch-difference and post-facto iteration is introduced, which plays a vital rule in the detection of the phase cycle slip to achieve the best orbit accuracy. The experiments of GRACE satellite OD with zero-difference IF combination observations spanning one year of 2010 show that, compared to the JPL reference orbits, the daily average 3D RMS is generally below 5.0cm for the float solution, while that is below 4.0cm for the fixed solution.</p><p>Secondly, to solve the problem that specific a-priori information like earth gravity field model must be involved in LEO’ reduced dynamic OD, the simultaneous solution method, which is specially on the relation with the kinematic OD and reduced dynamic OD, is used and the carrier-range, which can be recovered from phase observations once the kinematic OD process using Integer Ambiguity Resolution (IAR) technology is carried out, is naturally applied to this method. With the experiments based on the data over a period of the year of 2010, comes some evacuations, including the external checks on the accuracy of the orbits and the analysis on the earth gravity model. The numerical results show that, compared to the JPL reference orbits, the 3D RMS is below 3.0cm and the RMS is below 2.0cm for each component. As for the accuracy of gravity field model, compared to some contemporary significant earth gravity model, the model of the single month solution behaves very well below the 60 degree of the gravity field’s coefficients, while over the 60 degree, only the UTCSR model quite corresponds to the model computed by this method. Therefore, due to the promotion of the orbital accuracy and gravity field model, we suggest that the recovered carrier-range should be implemented in the simultaneous method for the better product solution of the LEO’s missions.</p>

scholarly journals Precise Orbit Determination of LEO Satellite Using Dual-Frequency GPS Data

2009 ◽  
Vol 26 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Yoo-La Hwang ◽  
Byoung-Sun Lee ◽  
Jae-Hoon Kim ◽  
Jae-Cheol Yoon
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Gps Data ◽  
Dual Frequency ◽  
Precise Orbit ◽  
Leo Satellite

scholarly journals New Results on the Motions of Asteroids in Resonances

1992 ◽  
Vol 152 ◽  
pp. 145-152 ◽  
Author(s):  
R. Dvorak
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Close Approach ◽  
Integration Time ◽  
Time Interval ◽  
Time Intervals ◽  
3 Dimensional ◽  
Special Cases ◽  
Good Agreement

In this article we present a numerical study of the motion of asteroids in the 2:1 and 3:1 resonance with Jupiter. We integrated the equations of motion of the elliptic restricted 3-body problem for a great number of initial conditions within this 2 resonances for a time interval of 104 periods and for special cases even longer (which corresponds in the the Sun-Jupiter system to time intervals up to 106 years). We present our results in the form of 3-dimensional diagrams (initial a versus initial e, and in the z-axes the highest value of the eccentricity during the whole integration time). In the 3:1 resonance an eccentricity higher than 0.3 can lead to a close approach to Mars and hence to an escape from the resonance. Asteroids in the 2:1 resonance with Jupiter with eccentricities higher than 0.5 suffer from possible close approaches to Jupiter itself and then again this leads in general to an escape from the resonance. In both resonances we found possible regions of escape (chaotic regions), but only for initial eccentricities e > 0.15. The comparison with recent results show quite a good agreement for the structure of the 3:1 resonance. For motions in the 2:1 resonance our numeric results are in contradiction to others: high eccentric orbits are also found which may lead to escapes and consequently to a depletion of this resonant regions.

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