Time filter

Source Type

Zhang S.J.,Harbin Institute of Technology | Cao X.B.,Harbin Institute of Technology | Zhang F.,Harbin Institute of Technology | He L.,Shanghai Aerospace Control Engineering Institute
Science in China, Series F: Information Sciences | Year: 2010

To determine the relative pose between an object and a single camera using 2D-to-3D point correspondences, a kind of iterative methods based on inverse projection ray approach is proposed. An iterative algorithm which is divided into depth recovery stage and absolute orientation stage is also proposed. In the first stage, the optimal translation vector is first computed in terms of rotation matrix via least square method, then the depths of the observed points are estimated by projecting the estimated point orthogonally to the inverse projection ray defined by the image point, and finally 3D points are reconstructed using the estimated depths from previous step. In the second stage, the optimal rotation matrix is estimated by applying Umeyama algorithm to fitting of the 3D model points and 3D estimated points. The above two stages are repeated until the result converges. The global convergence of the two-stage iterative algorithm is proven based on the global convergence theorem. Finally, a spacecraft docking application is implemented to test the effectiveness and convergence of the proposed algorithm by mathematical simulation and physical simulation. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.

Sun J.,Harbin Institute of Technology | Sun J.,Shanghai Aerospace Control Engineering Institute | Zhang S.-J.,Harbin Institute of Technology | Li B.-H.,Harbin Institute of Technology
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2013

An autonomous navigation algorithm is proposed using the sensor with functions of a star sensor and an ultraviolet earth sensor. The sensor has two Field of Views (FOVs ) named FOV1 and FOV2. The FOV1 is used for star sensor and for calculating the optical axis direction of the FOV1. The FOV2 is used for ultraviolet earth sensor and for calculating the vector of the earth. The state equation of integrated system is established by the deduced orbit dynamic model based on orbit six elements and the attitude kinematic model. Then, the observed equation of integrated system is established by using the difference of the measurement value and the estimated value, and the satellite orbit parameters were calculated according to the Discrete Extend Kalman Filter(DEKF)algorithm. An experiment on the ultraviolet sensor shows that not only the errors of satellite positions is improved from 1000 m to 500 m and the errors for satellite velocities are improved from 100 m/s to 40 m/s, but also the errors of periodic sine resulted from the angle between the sun light and ground level is eliminated. These results show the algorithm to be well robust.

Shijie Z.,Harbin Institute of Technology | Fenghua L.,Harbin Institute of Technology | Xibin C.,Harbin Institute of Technology | Liang H.,Shanghai Aerospace Control Engineering Institute
Chinese Journal of Aeronautics | Year: 2010

Visual sensors are used to measure the relative state of the chaser spacecraft to the target spacecraft during close range rendezvous phases. This article proposes a two-stage iterative algorithm based on an inverse projection ray approach to address the relative position and attitude estimation by using feature points and monocular vision. It consists of two stages: absolute orientation and depth recovery. In the first stage, Umeyama's algorithm is used to fit the three-dimensional (3D) model set and estimate the 3D point set while in the second stage, the depths of the observed feature points are estimated. This procedure is repeated until the result converges. Moreover, the effectiveness and convergence of the proposed algorithm are verified through theoretical analysis and mathematical simulation. © 2010 Chinese Journal of Aeronautics.

Xie Y.,Harbin Institute of Technology | Yi G.,Harbin Institute of Technology | Wang C.,Harbin Institute of Technology | Qu Y.,Harbin Institute of Technology | Qu Y.,Shanghai Aerospace Control Engineering Institute
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2012

In this paper investigate the alignment problem of a stationary based strapdown inertial navigation system. In order to improve the aligning accuracy and shorten the aligning time, a Gauss-Hermite filter (GHF) is adopted in the alignment model based on large azimuth misalignment angles. The nonlinear Gauss integration of multi-variables to the mean and covariance computation in the GHF is addressed. Since large azimuth misalignment angles will introduce the nonlinearity in the alignment error equations, this paper employs linear state transformation approach to obtain the analytic solution of the linear state vector in the underlying equations. The integration of multi-variables is thus converted to the integration of a single-variable. Hence the so called "dimension problem" in the application of GHF to alignment is solved without loss of accuracy. The proposed method is applied to a SINS, and it shows that the aligning accuracy of path angle is improved by 16% and the aligning time is reduced by 75% compared with extended Kalman filter (EKF) and unscented Kalman filter (UKF).

Cheng Y.,Nanjing University of Aeronautics and Astronautics | Jiang B.,Nanjing University of Aeronautics and Astronautics | Sun J.,Shanghai Aerospace Control Engineering Institute | Sun J.,Shanghai Key Laboratory of Space Intelligent Control Technology | And 2 more authors.
ICIC Express Letters | Year: 2011

This paper is concerned with the design of a robust actuator fault diagnosis and tolerant control scheme for satellite attitude control systems. A bank of sliding mode observers (SMOs) are firstly investigated to detect and isolate single actuator fault for satellite attitude control systems with input disturbance. When an actuator undergoes unknown fault, it is disabled. Under such condition, a novel fault tolerant controller based on sliding mode control method is proposed to keep system safe using the remaining actuators. Simulation results demonstrate the effectiveness of the proposed method for satellite attitude control systems. © 2011 ISSN 1881-803X.

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