Science and Technology on Aerospace Flight Dynamics Laboratory

Beijing, China

Science and Technology on Aerospace Flight Dynamics Laboratory

Beijing, China
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Wang Y.,National University of Defense Technology | Sun S.,Xi'an Jiaotong University | Li L.,Science and Technology on Aerospace Flight Dynamics Laboratory
Journal of Guidance, Control, and Dynamics | Year: 2014

A study was conducted to propose a adaptively robust Kalman filter (ARKF) for tracking a maneuvering vehicle. The ARUKF had the potential to reduce the effect of the dynamics model error and the measurement model error simultaneously. The fading factor based on the innovation sequence orthogonal principle was derived to overcome the limitation of the ARKF. The ARKF had the potential to reduce the effect of the dynamics model error, with fewer iterations. The cost function of an improved adaptively robust Kalman filter (IARKF) was derived and the procedure in embedding the structure of the IARKF into the unscented Kalman filter (UKF) framework was discussed. The method of forming the fading factor based on the innovation sequence orthogonal principle was also provided. The ARUKF effectively tracked the movement of the vehicle when the orbital maneuver, measurement outlier, and contaminated noise occurred simultaneously.


Yin F.,Beijing University of Posts and Telecommunications | Zhang A.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Ren T.,Science and Technology on Aerospace Flight Dynamics Laboratory | And 6 more authors.
Optics Express | Year: 2014

In this paper, we propose a phase-conjugation-based fast radio frequency (RF) phase auto stabilization technique for long-distance fiber delivery. By phase conjugation at the center site, the proposed scheme prephase- promotes the RF signal with the shift which is acquired by round-trip transferring another RF whose frequency is half of the one to be sent. Such phase pre-promotion is then used to counteract exactly the following retard induced by one-way delivery. Different from the previous phase-lockingloop- based schemes, the proposed open-loop design avoids the use of any tunable parts and dynamic phase tracking, enabling a fast phase stabilization at the remote site. An end-less compensation capacity can also be achieved. Our design is analyzed by theory. Experimentally, the new scheme is verified by transferring a frequency of 2.42 GHz through a 30-km optical fiber link. Significant phase drift compression is observed. The rapid phase stabilization is verified by introducing sudden time delay change into the link. The recovery time equals to the round-trip time of the link plus the transitional duration of the delay change, which is much shorter than the traditional trial-and-error phase locking loop. Important issues of the system design are discussed. © 2014 Optical Society of America.


Zhang A.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Yin F.,Beijing University of Posts and Telecommunications | Ren T.,Science and Technology on Aerospace Flight Dynamics Laboratory | And 5 more authors.
Optics Express | Year: 2014

In this paper, we propose and demonstrate a phase stabilized wideband downlink transmission scheme, which directly transmits the received radio frequency (RF) signals from remote antennas to central station. A reference RF tone is round-trip transferred between the central station and remote end to obtain the delay variation caused by the fiber link. The delay variation is then used to alter a tunable laser. Since optical carriers with different wavelengths propagate at different velocities in fiber, a tunable optical delay line is realized to cancel the delay variation of the fiber link. The tunable delay range is in proportion to the length of the fiber link, which means a very long delivery distance can be expected. Experimentally, a RF signal at frequency of 2.50 GHz has been downlink transferred through a 45 km fiber link, with stability of 3.3×10-13 at 1 s and 7.5x10-17 at 104s. ©2014 Optical Society of America.


Zhang A.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Yin F.,Beijing University of Posts and Telecommunications | Ren T.,Science and Technology on Aerospace Flight Dynamics Laboratory | And 7 more authors.
Optics Letters | Year: 2013

We propose and demonstrate a novel stable radio frequency (RF) delivery system based on a radio-over-fiber link. The proposed scheme acts as a long phase-locking loop where an optical tunable delay line is involved to compensate dynamically for the time-delay variation that arises from fiber-link fluctuation. An optical carrier with variable wavelength under fiber-link dispersion results in the desired tunable delay. The tunable range is in proportion to the length of the fiber link, so a large phase-error correction capacity under long-distance delivery can be realized. The large as well as fine optical-delay tunability is experimentally demonstrated, and the RF reference of 2.42 GHz is transferred for 54 km where a time jitter compression factor of 588 is achieved. © 2013 Optical Society of America.


Yin F.,Beijing University of Posts and Telecommunications | Wu Z.,Beijing University of Posts and Telecommunications | Dai Y.,Beijing University of Posts and Telecommunications | Ren T.,Science and Technology on Aerospace Flight Dynamics Laboratory | And 5 more authors.
Optics Letters | Year: 2014

In this Letter we demonstrate a fiber link capable of stable time signal transfer utilizing our active long-distance radio frequency (RF) stabilization technology. Taking advantage of the chromatic dispersion in optical fiber, our scheme compensates dynamically the link delay variation by tuning the optical carrier wavelength to phase lock a roundtrip RF reference. Since the time signal and the RF reference are carried by the same optical carrier, a highly stable time transfer is achieved at the same time. Experimentally, we demonstrate a stability of the time signal transfer over 50-km fiber with a time deviation of 40 ps at 1-s average and 2.3 ps at 1000-s average. The performance of the RF reference delivery is also tested, with an Allan deviation of 2 × 10? 15 at 1000-s average. According to our proposal, a simultaneous stable time and frequency transfer is expected. © 2014 Optical Society of America.


Wang Y.,National University of Defense Technology | Zheng W.,National University of Defense Technology | Sun S.,Xi'an Jiaotong University | Li L.,Science and Technology on Aerospace Flight Dynamics Laboratory
Advances in Space Research | Year: 2013

The objective of this paper is to investigate and reduce the impact of the errors in the planetary ephemerides on X-ray pulsar-based navigation system for Earth-orbiting satellite. Expressions of the system biases caused by the errors in the planetary ephemerides are derived. The result of investigation has shown that the impact of the error in Earth's ephemeris is must greater than the errors in the other ephemerides and would greatly degrade the performance of X-ray pulsar-based navigation system. Moreover, the system bias is modeled as a slowly time-varying process, and is handled by including it as a part of navigation state vector. It has been demonstrated that the proposed navigation system is completely observable, and some simulations are performed to verify its feasibility. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.


Li J.,CAS National Astronomical Observatories | Li J.,University of Chinese Academy of Sciences | Ma G.,CAS National Astronomical Observatories | Maruyama T.,Japan National Institute of Information and Communications Technology | And 2 more authors.
Journal of Geophysical Research: Space Physics | Year: 2012

Post-sunrise intense ionospheric irregularities at low to mid-latitudes are reported for the first time. A method based on spaced-receiver technique is proposed to estimate the apparent drift velocity of the irregularities by using the correlation of the slant total electron content (TEC) from 3 GPS receivers. The irregularities were detected at 23∼45°N by the GPS Earth Observation Network (GEONET) of Japan from ∼0455 LT to ∼1051 LT on 21 March 2001 during the recovery phase of the magnetic storm. At the corresponding time spread F was observed with 3 ionosondes located meridionally at Okinawa (127.8°E, 26.3°N; 20.7°N magnetic latitude), Kokubunji (139.5°E, 35.7°N; 30.0°N magnetic latitude) and Wakkanai (141.7°E, 45.4°N; 40.5°N magnetic latitude), while an intense negative ionospheric storm was processing and propagating from mid to lower latitudes. The irregularities were seen as plasma bubbles by the Defense Meteorological Satellite Program (DMSP) in-situ measurements. Westward drift with the speed of ∼100 m/s was estimated by spaced receivers from GEONET and confirmed by DMSP during the evolution of the irregularities. The plasma bubbles at mid-latitude sustained ∼1.5 hour after sunrise, and at the lower latitudes they survived more than 4 hours after sunrise. The observations suggested that the irregularities were generated by an eastward electric field associated with the disturbance dynamo, and the long time existence of the irregularities after sunrise seemed to be related to the daytime intense negative ionospheric storm on 21 March. © 2012. American Geophysical Union. All Rights Reserved.


Tang J.,Nanjing University | Tang J.,Science and Technology on Aerospace Flight Dynamics Laboratory | Cheng H.,CAS National Astronomical Observatories | Liu L.,Nanjing University | Liu L.,Science and Technology on Aerospace Flight Dynamics Laboratory
Water Resources Research | Year: 2014

Heavy droughts have frequently struck Southwestern China in recent years. A major consequence of these droughts is the loss of terrestrial water storage (TWS) which affects agriculture, civil life, and industry production and results in serious social and economic losses. The satellite gravimetry has been proved an effective way to estimate hydrological variations over the globe, and we use the monthly gravity solutions from the Gravity Recovery and Climate Experiment (GRACE) satellite mission and extract the hydrological variations from the regional gravity signal. Here we show that the recent heavy droughts in Southwestern China have caused observable nonseasonal gravity changes in the monthly GRACE solutions. Two heavy droughts in September 2009 to May 2010 and August 2011 to January 2012 have resulted in significant TWS deficit up to hundreds of gigatons in Southwestern China. It is found that the latter drought in 2011-2012 is the most severe one in Southwestern China over the decade, hitting large areas, and causing heavy TWS deficit. Affected by the recent droughts, the GRACE estimate shows a gradual decrease in the regional TWS during the recent 4 years in Southwestern China with a nominal rate of-13.3-±-7.5 mm/yr, which indicates the severity of the TWS deficit in this area. Key Points GRACE is capable to capture recent heavy droughts in Southwestern China The TWS is gradually decreasing in Southwestern China due to recent droughts The TWS change is mainly controlled by rainfall and affected by global climate © 2014. American Geophysical Union. All Rights Reserved.


Xu X.Q.,Chinese Academy of Sciences | Zotov L.,Science and Technology on Aerospace Flight Dynamics Laboratory | Zhou Y.H.,Moscow State University
Lecture Notes in Electrical Engineering | Year: 2012

Earth orientation parameters (EOP) are essential for transformation between the celestial and terrestrial coordinate systems, which has important applications in the Earth sciences, astronomy and satellite navigation. The latter cannot be considered as self-reliant without accurate EOP predictions, which, in particular, are required for real-time precise orbit determination. In this paper we firstly describe the principles and analyze the characteristics of several EOP prediction methods. Then, according to the forecast accuracy, the weights are assigned to EOP predictions to get a combined solution. Results show that no single forecasting method is suitable for all the parameters at different time spans. The combined solution integrates advantages of different prediction methods, which avoid the limitations and instability of any of them. The resultant combined prediction is issued to the JPL Earth Orientation Parameters Combination of Prediction Pilot Project (EOPC PPP). © 2012 Springer-Verlag.


Meng Z.,Northwestern Polytechnical University | Meng Z.,Science and Technology on Aerospace Flight Dynamics Laboratory | Huang P.,Northwestern Polytechnical University | Huang P.,Science and Technology on Aerospace Flight Dynamics Laboratory
Proceedings of the 2013 IEEE 8th Conference on Industrial Electronics and Applications, ICIEA 2013 | Year: 2013

The tethered space robot system (TSR) will play a significant role in future on-orbit capture. In this paper, the approach model is derived and the coordinated approach control method is studied which contains an optimal open-loop controller and a feedback controller. The optimal open-loop control law is designed by Gauss pseudospectral method. Then, the approach model is linearized along the open-loop trajectory and the feedback controller is designed by linear quadratic regulator which is simpler and more efficient than the popular receding-horizon controller. The simulation results show that the approach control method is effective, even in the presence of initial perturbations, the tracking errors of tether tension and other disturbances. © 2013 IEEE.

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