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Ren X.,Navigation System Technology Laboratory | Ren X.,Beihang University | Le Y.,Navigation System Technology Laboratory | Le Y.,Beihang University | And 6 more authors.
IET Electric Power Applications | Year: 2017

In this study, a combined radial-axial hybrid magnetic bearing (CRAHMB) with four poles is designed for highspeed brushless DC motor. Owing to the small distance of radial and axial unit of CRAHMB, the magnetic flux leakage (MFL) in both radial and axial directions is complex and serious. This study focuses on effective analytical model and optimisation of CRAHMB including flux leakage of permanent magnet circuit and control electromagnetic circuit. MFL analytical model was built based on equivalent magnetic circuit method. Under the condition of satisfying the maximum bearing capacity, the MFL coefficients were optimised with sequence quadratic programming method. A set of optimum parameters were suggested. MFL before and after optimisation are compared by finite element method. Finally, current stiffness calculated with optimised analytical model was verified on a DC motor experiment. The result shows the accuracies of both the axial and radial current stiffness are enhanced. © The Institution of Engineering and Technology 2016.


Fang J.,Beihang University | Fang J.,Science and Technology on Inertial Laboratory | Fang J.,Navigation System Technology Laboratory | Han X.,Beihang University | And 2 more authors.
Journal of Navigation | Year: 2013

The Position and Orientation System (POS) is a special Strapdown Inertial Navigation System (SINS)/Global Positioning System (GPS) integrated system, widely employed in airborne remote sensing. In-Flight Alignment (IFA) is an effective way to improve the accuracy and speed of initial alignment for an airborne POS. IFA is normally accomplished with references from the position and velocity of GPS for SINS, so that unstable GPS measurements will result in poor alignment accuracy. To improve alignment accuracy under unstable GPS conditions, an adaptive filtering algorithm of the Second-order Divided Difference filter (DD2) based on adaptive innovation estimation is proposed, which introduces calculated innovation covariance directly into computation of the filter gain matrix. Then, the adaptive DD2 algorithm is used for the IFA of the POS with a large initial heading error. To validate the proposed algorithm, simulations are undertaken, followed by IFA experiments for the prototype of the airborne POS (TX-F30) under a turning manoeuvre in a car-mounted experiment, and under an 8 manoeuvre in-flight. The simulations and experimental results show that the proposed algorithm can reach better alignment accuracy under unknown statistical characteristic of GPS measurement noises. Copyright © The Royal Institute of Navigation 2012.


Cui P.,Beihang University | Cui P.,Science and Technology on Inertial Laboratory | Cui P.,Navigation System Technology Laboratory | Liu F.,Beihang University | And 2 more authors.
Mathematical Problems in Engineering | Year: 2012

In view of the issue of rapid attitude maneuver control of agile satellite, this paper presents an attitude-tracking control algorithm with path planning based on the improved genetic algorithm, adaptive backstepping control as well as sliding mode control. The satellite applies double gimbal control moment gyro as actuator and is subjected to the external disturbance and uncertain inertia properties. Firstly, considering the comprehensive mathematical model of the agile satellite and the double gimbal control moment gyro, an improved genetic algorithm is proposed to solve the attitude path-planning problem. The goal is to find an energy optimal path which satisfies certain maneuverability under the constraints of the input saturation, actuator saturation, slew rate limit and singularity measurement limit. Then, the adaptive backstepping control and sliding mode control are adopted in the design of the attitude-tracking controller to track accurately the desired path comprised of the satellite attitude quaternion and velocity. Finally, simulation results indicate the robustness and good tracking performance of the derived controller as well as its ability to avert the singularity of double gimbal control moment gyro. © 2012 Peiling Cui and Fuyu Liu.


Ma Y.,Beihang University | Ma Y.,Science and Technology on Inertial Laboratory | Ma Y.,Navigation System Technology Laboratory | Fang J.,Beihang University | And 8 more authors.
Journal of Navigation | Year: 2014

The observability of error states in Inertial Navigation System/Global Positioning System (INS/GPS) integration is of great importance. Rank tests or null space tests of the observability matrix have been adopted by previous works, however, for a time-varying system with a high-dimension error state vector, it is very difficult to analyse the observability matrix by these traditional methods. In this paper, the decoupled observability analysis method is proposed for an 18-dimensional INS/GPS integration system. By reducing the dimension of coupling error states, several six-dimensional decoupled observability sub-matrices are obtained, which make the observability analyses easier. The observability results of error states are obtained by the proposed method. Covariance simulation with an Extended Kalman filter (EKF) and a flying test were performed which confirmed the theoretical results. Copyright © The Royal Institute of Navigation 2014 Â.


Liu X.,Navigation System Technology Laboratory | Liu X.,Beihang University | Han B.,Navigation System Technology Laboratory | Han B.,Beihang University
IEEE Transactions on Magnetics | Year: 2014

The magnetic bearing's (MB) performance is determined by its electromagnetic and mechanical parameters, which should be optimized to meet the working requirements. Many optimal methods of MB have been only focused on a single objective, which may be limited to a small amount of aspects, while other important ones are ignored. A multiobjective optimization (MOO) model to design the MB considered for a better comprehensive property is proposed in this paper. After modeling the equivalent circuit model whose simplification has been clarified by finite element method, we provide the constraints and optimal objectives in the shape of analytical expression. First, every single objective is solved to get utilization by complex method, then, a novel concept of utilization vector is proposed to calculate the weighting coefficients to resolve the MOO problem, by chaotic local search particle swarm optimization with the constraints as penalty functions. MOO design methods are applied for one type of two-degree-of-freedom hybrid MB, and this method could obtain a better balanced overall result, improving the levitated force and decreasing flux density in the air gap. © 2012 IEEE.


Cui P.,Beihang University | Cui P.,Science and Technology on Inertial Laboratory | Cui P.,Navigation System Technology Laboratory | Zhang H.,Beihang University | And 8 more authors.
Sensors (Switzerland) | Year: 2012

Integrating the advantage of magnetic bearings with a double gimble control moment gyroscope (DGCMG), a magnetically suspended DGCMG (MSDGCMG) is an ideal actuator in high-precision, long life, and rapid maneuver attitude control systems. The work presented here mainly focuses on performance testing of a MSDGCMG independently developed by Beihang University, based on the single axis air bearing table. In this paper, taking into sufficient consideration to the moving-gimbal effects and the response bandwidth limit of the gimbal, a special MSDGCMG steering law is proposed subject to the limits of gimbal angle rate and angle acceleration. Finally, multiple experiments are carried out, with different MSDGCMG angular momenta as well as different desired attitude angles. The experimental results indicate that the MSDGCMG has a good gimbal angle rate and output torque tracking capabilities, and that the attitude stability with MSDGCMG as actuator is superior to 10-3°/s. The MSDGCMG performance testing in this paper, carried out under moving-base condition, will offer a technique base for the future research and application of MSDGCMGs. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

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