检索结果-南通市图书馆

Chinese Journal of Aeronautics 2017年第1期30卷 358-367页

作者： He Yanzhao Zheng Shiqiang fang jiancheng School of Instrumentation Science and Opto-electronics Engineering Beihang University Beijing 100083 China Beijing Engineering Research Center of High-Speed Magnetically Suspended Motor Technology and Application Beijing 100083 China

The start-up current control of the high-speed brushless DC（HS-BLDC） motor is a challenging research topic. To effectively control the start-up current of the sensorless HS-BLDC motor, an adaptive control method is proposed based on the adaptive neural network（ANN）inverse system and the two degrees of freedom（2-DOF） internal model controller（IMC）. The HS-BLDC motor is identified by the online least squares support vector machine（OLS-SVM） algorithm to regulate the ANN inverse controller parameters in real time. A pseudo linear system is developed by introducing the constructed real-time inverse system into the original HS-BLDC motor system. Based on the characteristics of the pseudo linear system, an extra closed-loop feedback control strategy based on the 2-DOF IMC is proposed to improve the transient response performance and enhance the stability of the control system. The simulation and experimental results show that the proposed control method is effective and perfect start-up current tracking performance is achieved.

关键词： Adaptive control Brushless DC motors Inverse systems Internal model controller Neural networks Start-up Support vector machines

维普期刊数据库

A transfer alignment method for airborne distributed POS with three-dimensional aircraft flexure angles

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第9期61卷 190-204页

作者： Xiaolin GONG Longjun CHEN jiancheng fang Gang LIU School of Instrumentation Science and Opto-electronics Engineering Beihang University Science and Technology on Inertial Laboratory Beihang University

An airborne distributed position and orientation system(POS) appears to satisfy the requirement of multi-point motion parameters measurement. This relies on transfer alignment from a high precision master system to slave systems to obtain high accuracy motion parameters of all points. A key problem for a distributed POS involves determining a method to treat the aircraft flexure appropriately and achieve high precision transfer alignment. In this study, the effect of aircraft flexure on transfer alignment accuracy for airborne earth observation is first analyzed. Based on this, the error model of transfer alignment that considers three-dimensional flexure angles are established, and a transfer alignment based on parameter identification unscented Rauch-Tung-Striebel smoother(PIURTSS) is proposed. The simulations results show that the transfer alignment method based on PIURTSS effectively improves the estimation accuracy.

关键词： position and orientation system distribution airborne earth observation transfer alignment unscented transformation Rauch-Tung-Striebel smoother

Interlaced optimal-REQUEST and unscented Kalman filtering for attitude determination

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2013年第2期26卷 449-455页

作者： Quan Wei Xu Liang Zhang Huijuan fang jiancheng Science and Technology on Inertial Laboratory Key Laboratory of Fundamental Science for National Defense-Novel Inertial Instrument & Navigation System Technology Beihang University

Aimed at low accuracy of attitude determination because of using low-cost components which may result in non-linearity in integrated attitude determination systems, a novel attitude determination algorithm using vector observations and gyro measurements is presented. The various features of the unscented Kalman filter （UKF） and optimal-REQUEST （quaternion estimator） algorithms are introduced for attitude determination. An interlaced filtering method is presented for the attitude determination of nano-spacecraft by setting the quaternion as the attitude representation, using the UKF and optimal-REQUEST to estimate the gyro drifts and the quaternion, respectively. The optimal-REQUEST and UKF are not isolated from each other. When the optimal-REQUEST algorithm estimates the attitude quaternion, the gyro drifts are estimated by the UKF algorithm synchronously by using the estimated attitude quaternion. Furthermore, the speed of attitude determination is improved by setting the state dimension to three. Experimental results show that the presented method has higher performance in attitude determination compared to the UKF algorithm and the traditional interlaced filtering method and can estimate the gyro drifts quickly.

关键词： Attitude determination Hybrid simulation Interlaced filtering Optimal-REQUEST Unscented Kalman filter

维普期刊数据库

Adaptive two-filter smoothing based on second-order divided difference filter for distributed position and orientation system

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2019年第9期62卷 130-143页

作者： Jianli LI Siyuan ZOU Bin GU jiancheng fang School of Instrument Science and Opto-electronic Engineering Beihang University

The distributed position and orientation system(POS) uses transfer alignment to accurately measure multi-node time-spatial reference information, which is necessary for compensating the motion error of imaging sensors used in aerial surveys. Lever-arm deformation in transfer alignment will result in time-varying covariance of measurement noise, which decreases the estimation accuracy. To address this problem, a second-order adaptive divided difference two-filter smoother(ADDTFS) is proposed for transfer alignment. The second-order adaptive divided difference filter(ADDF2) severs as the forward filter to address nonlinearity in the system. The ADDF2 can estimate the measurement noise covariance in real time based on adaptive estimation using innovation information. The weighted statistical linear regression formulation is used in the backward filter to independently estimate the states and error covariance *** the forward and backward results are combined, to obtain high-precision estimation results in postprocessing. Finally, the vehicle experiment results show that the proposed method can improve the attitude precision of transfer alignment in a distributed POS by 27.84%, which has been successfully applied to motion compensation of airborne interferometric synthetic aperture radar(InS AR).

关键词： distributed POS transfer alignment integrated navigation two-filter smoother divided difference filter

Angular velocity estimation using characteristics of star trails obtained by star sensor for spacecraft

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第1期64卷 201-214页

作者： Xiaolin NING Pingping CHEN Yueqing HUANG Weiren WU jiancheng fang School of Instrumentation Science & Opto-electronics Engineering Beihang University Lunar Exploration and Space Program Center China National Space Administration

Many studies have been conducted about angular velocity estimation using star sensors, and fairly good performance is achieved when the spacecraft is working at low-dynamic environments. However,when the spacecraft rotates at a large angular velocity, the star image will become blurred, which makes it difficult to identify and recognize star centroids, which, in turn, reduces the accuracy of angular velocity estimation. Therefore, to solve the problem with angular velocity estimation in highly dynamic situations,this research studies a method of angular velocity estimation using blurred star images. The length and ending point coordinates of star trails obtained from these blurred star images are used for a series of processes, which includes the pre-processing of blurred star images, determination of starting and ending points, thinning and selection of star trails, and calculation of trail lengths. Simulations show that the effectiveness of the proposed method in highly dynamic situations and the angular velocity estimation errors in constant and sinusoidal variation are reduced by at least 66% and 62%, respectively, compared with those of the traditional method.

关键词： angular velocity estimation star sensor blurred star images star trail characteristics unscented Kalman filter

Fast Position and Velocity Determination for Pulsar Navigation Using NML and LSM

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2017年第6期26卷 1325-1329页

作者： LIU Jin WU Jin XIONG Ling fang jiancheng LIU Gang College of Information Science and Engineering Wuhan University of Science and Technology School of Instrumentation Science and Opto-electronics Engineering Beihang University

To reduce the computational cost, a Fast position and velocity joint determination(FPVD) method based on the Near-maximum likelihood(NML) and the Least square method(LSM) is proposed for X-ray pulsar navigation. Considering the fact that the Doppler effects caused by the velocity of the spacecraft alters the X-ray pulse Time-of-arrival(TOA), we adopt the NML to obtain multi-TOAs, and then utilize the LSM to estimate the variation of TOAs instead of the pulsar profile distortion adopted by the Maximum-likelihood(ML) estimation method. Finally, according to the variation value and TOAs, the position and velocity information of the spacecraft are calculated. The simulation results have demonstrated that the FPVD method is far faster than the ML estimation method, and its accuracy approaches the CramerRao lower bound(CRLB).

关键词： Velocity determination Pulsar Maximum likelihood Least square method

Optical Rotation Detection for Atomic Spin Precession Using a Superluminescent Diode

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Photonic Sensors 2019年第2期9卷 135-141页

作者： Xuejing LIU Yang LI Hongwei CAI Ming DING jiancheng fang Wei JIN School of Inst ru men ta tion Science and Opto-electronics Engineering Beihang University Beijing 100191 China

A superluminescent diode (SLD) as an alternative of laser is used to detect optical rotation for atomic spin precession. A more uniform Gauss configuration without additional beam shaping and a relatively high power of the SLD have a potential for atomic magnetometers, which is demonstrated in theory and experiments. In addition, the robustness and compactness enable a more practical way for optical rotation detections, especially for applications in magnetoencephalography systems.

关键词： Superluminescent diode atomic magnetometer magnetoencephalography atomic spin precessiondetection Larmor precession

Recursive adaptive filter using current innovation for celestial navigation during the Mars approach phase

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第3期60卷 168-182页

作者： Xiaolin NING Zhuo LI Weiren WU Yuqing YANG jiancheng fang Gang LIU School of Instrumentation Science & Opto-Electronics Engineering Beihang University

Celestial navigation is a commonly used autonomous navigation technique for deep space navigation.A nonlinear filter such as the unscented Kalman filter(UKF) is typically applied in a celestial navigation system(CNS). However, on account of being subject to a number of factors, such as ephemeris errors and centroid determination, the measurement model error of a CNS cannot be accurately determined. The analysis conducted in this study also shows that the measurement model error is time-variant during the Mars approach *** implies that covariance matrix of the measurement error R is usually inaccurate, which may induce large estimation errors that even result in filter divergence. Some adaptive methods are able to address this ***, traditional adaptive filters, for scaling R, usually require a sequence of innovation and are affected by the statistic window size. A new recursive adaptive UKF(RAUKF) is proposed in this paper, which only uses current innovation to scale R. The navigation performance of the proposed RAUKF method is compared with some traditional adaptive filters through simulations. The results show that this method is better than traditional adaptive filters in a CNS during the Mars approach phase.

关键词： deep space adaptive UKF navigation Mars approach variant noise

Spacecraft angular velocity estimation method using optical flow of stars

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第11期61卷 99-112页

作者： Xiaolin NING Zonghe DING Pingping CHEN Weiren WU jiancheng fang Gang LIU School of Instrumentation Science & Opto-electronics Engineering Beihang University Lunar Exploration and Space Program Center China National Space Administration

Angular velocity is a crucial parameter for spacecraft navigation, which, at present, is mainly obtained by using gyroscopes. Several studies have been performed on angular velocity estimation using star sensors when data from gyroscopes are not available. Most of the previous angular velocity estimation methods using star sensors are based on information on the attitude or star vector measurements. In this paper,an angular velocity estimation method using the optical flow(OF) directly from the star images is proposed,which, unlike the previous methods, requires star coordinates in two consecutive images only. Because the procedure of star identification is eliminated, the corresponding high computation requirement is *** demonstrate that the proposed method has a robust performance in terms of computational cost and the number of stars in the field of view(FOV) compared with the previous methods. Finally, certain affecting factors are analyzed, including lens distortion, star senor instantaneous FOV(IFOV), star number,and accuracy of the star sensor.

关键词： angular velocity star sensor optical flow star images Kalman filter

A new SINS/RCNS integrated navigation method based on star pixel coordinates

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2023年第9期66卷 295-296页

作者： Guangxin SONG Yuqing YANG Xiaolin NING jiancheng fang Weiren WU School of Instrumentation Science and Opto-electronics Engineering Beihang University School of Research Institute for Frontier Science Beihang University Lunar Exploration and Space Program Center China National Space Administration

The traditional strapdown inertial navigation system(SINS)/celestial navigation system(CNS) integrated navigation system using the starlight vector or posture difference calculated by SINS and CNS as a measurement can correct the posture error of SINS, but not the position error [1]. The refraction celestial navigation system(RCNS) can independently provide the position information.

关键词：