National Key Laboratory of Aerospace Flight Dynamics

Fengcheng, China

National Key Laboratory of Aerospace Flight Dynamics

Fengcheng, China

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Zhenqi H.,Northwestern Polytechnical University | Zhenqi H.,National Key Laboratory of Aerospace Flight Dynamics | Ke Z.,Northwestern Polytechnical University | Ke Z.,National Key Laboratory of Aerospace Flight Dynamics | And 2 more authors.
Advances in Astronomy | Year: 2017

Keeping the flying formation of spacecraft is a key problem which needs to be solved in deep space exploration missions. In this paper, the nonlinear dynamic model of formation flying is established and a series of transformations are carried out on this model equation. By using SDRE (State-Dependent Riccati Equation) algorithm, the optimal control of flying formation is realized. Compared with the traditional control method based on the average orbit elements and LQR (Linear Quadratic Regulator) control method, the SDRE control method has higher control precision and is more suitable for the advantages of continuous control in practical engineering. Finally, the parameter values of the sun-earth libration point L2 are substituted in the equation and simulation is performed. The simulation curves of SDRE controller are compared with LQR controller. The results show that the SDRE controllers time cost is less than the LQR controllers and the former's fuel consumption is less than the latter's in the system transition process. © 2017 He Zhenqi et al.


Zhu Z.,Northwestern Polytechnical University | Zhu Z.,National Key Laboratory of Aerospace Flight Dynamics | Zhang H.,Northwestern Polytechnical University | Zhang H.,National Key Laboratory of Aerospace Flight Dynamics | And 2 more authors.
Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University | Year: 2017

Free-floating space robot system is a very complicated nonlinear analysis. Traditional control strategy cannot meet the technical requirements when considering uncertain terms and external disturbances. For this reason, the influence of the uncertainty to the system is considered in this article. This article regard the control error and the error rate as system state. Basing on neural network on-line modeling technique, design the change rate of network weights and approach the uncertain parts by weight of training. Then design adaptive neural network control item, which can be used to amend nominal-model-based control and compensate the control error caused by uncertain terms. Meanwhile, The stability of control system is proved. The numerical simulation of 7 DOF(degree of freedom)space robot show that with the adaptive neural network controller proposed in this article, the end-effector with disturbances and load can also close to the desired trajectory and converge when the error within a finite range. The controller performs better than traditional PID controller. © 2017, Editorial Board of Journal of Northwestern Polytechnical University. All right reserved.


Cui J.-F.,National Key Laboratory of Aerospace Flight Dynamics | Zhang K.,National Key Laboratory of Aerospace Flight Dynamics | Lu M.-B.,National Key Laboratory of Aerospace Flight Dynamics
Kongzhi yu Juece/Control and Decision | Year: 2015

The computational load of traditional tensor product distributed compensation(TPDC) control method explodes with the dimensionality of the parameter vector of the parameter-varying state-space model. So it is difficult for the traditional method to be applied in the high dimensional LPV system. Therefore, a TPDC control method based on uniform design is proposed, which method utilizes the uniform design to acquire the discretized tensor of the LPV system. As a consequence, the discretized data have little correlation with the dimensionality of the parameter vector. The simulation results show that the control method can reduce the computational load effectively without degradation of the control performance. ©, 2015, Northeast University. All right reserved.


Wang Z.G.,Northwestern Polytechnical University | Wang Z.G.,National Key Laboratory of Aerospace Flight Dynamics | Zhang N.,Northwestern Polytechnical University | Zhang N.,National Key Laboratory of Aerospace Flight Dynamics
Applied Mechanics and Materials | Year: 2013

Since the traditional parabola trajectory is prone to be head off, wavy trajectory has the flight characteristics of defense penetration ability and increasing range. On the basis of flight characteristics of wavy trajectory missile, a method for flight program angle was designed. A specific formula was given. An optimization model was established. A conjugate gradient optimizing algorithm was used to solve the model and the result is compared with the former trajectory. It shows that optimized wavy trajectory can prove the feasibility of increasing range and valid defense penetration ability. © (2013) Trans Tech Publications, Switzerland.


Wang Z.G.,Northwestern Polytechnical University | Wang Z.G.,National Key Laboratory of Aerospace Flight Dynamics | Li W.,Northwestern Polytechnical University | Li W.,National Key Laboratory of Aerospace Flight Dynamics
Applied Mechanics and Materials | Year: 2013

On the basis of dual-spin projectile multi-body characteristics, the angular motion model is established in the quasi-body coordinates. Through linearization, the system dynamic stability factor and gyroscopic stability factor are obtained by differential equations characteristic roots. There is also informative to compare the dual-spin projectile gyroscopic stability factor to the conventional rigid projectile results. The comparison can be viewed where the influence of the spin rates ration γf/γa and the ratio of inertia moments Cf/Caon the ratio Sg/Sy g of the gyroscopic stability factors. Through the numerical example, the dual-spin projectile has a similar stability to that of a conventional rigid projectile, and the curves of the relationship between the ratio Sg/Sy g of the gyroscopic stability factors with the ratio of spin rates γf/γa and the ratio of inertia moments Cf/Ca are got by simulation. © (2013) Trans Tech Publications, Switzerland.


Wang Z.G.,Northwestern Polytechnical University | Wang Z.G.,National Key Laboratory of Aerospace Flight Dynamics | Deng Y.F.,Northwestern Polytechnical University | Deng Y.F.,National Key Laboratory of Aerospace Flight Dynamics
Applied Mechanics and Materials | Year: 2013

The problem of spacecraft attitude estimation utilizing star sensors and gyros is considered in this paper. Since the errors of the quaternion outputs of star sensors projected on the direction along the optical axis is higher than the other two directions, a novel method to increase the estimation accuracy of the attitude filter is presented, by producing observation vectors along the direction of the light axes, which are composed of a couple of quaternion outputs from different star sensors. The proposed algorithm is validated and proved more precise by numerical simulations. © (2013) Trans Tech Publications, Switzerland.


Wang Z.G.,Northwestern Polytechnical University | Wang Z.G.,National Key Laboratory of Aerospace Flight Dynamics | Yan S.,Northwestern Polytechnical University | Yan S.,National Key Laboratory of Aerospace Flight Dynamics
Applied Mechanics and Materials | Year: 2013

The problem of low accuracy for classic guidance law is considered in this paper. Based on the mature theory used in missiles, this paper presents an integrated guidance law for reentry vehicles. At the initial stage of reentry flight, standard trajectory guidance law is employed, and then converts to 3dof proportional guidance law when this vehicle is close to the target. Simulation results are provided to demonstrate the accuracy of the proposed integrated guidance law. © (2013) Trans Tech Publications, Switzerland.


Yan X.-D.,Northwestern Polytechnical University | Yan X.-D.,National Key Laboratory of Aerospace Flight Dynamics | Wang Z.,Northwestern Polytechnical University
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2013

It's an effective way to improve the guidance adaptability for hypersonic glide vehicle (HGV) by applying trajectory planning. First, the target plane coordinate frame was defined. Then, taking the coordinate frame as the reference coordinate frame, dynamic equations with the normalized energy as independent variable were deduced, which have the advantages of fixed integral interval, and cross-range and longitudinal range could be denoted by the equation states. Based on the equations, longitudinal trajectory planning method was put forward as well as lateral trajectory planning method. With the combination of above methods and the trajectory of lateral curvature, a three-dimensional trajectory planning method has been implemented. It is shown that the proposed method can fulfill trajectory planning for HGV rapidly and accurately.


Wang Z.G.,Northwestern Polytechnical University | Wang Z.G.,National Key Laboratory of Aerospace Flight Dynamics | Zhang Z.N.,Northwestern Polytechnical University | Zhang Z.N.,National Key Laboratory of Aerospace Flight Dynamics
Applied Mechanics and Materials | Year: 2013

Modeling and simulation method of unsteady aerodynamics on morphing wings were investigated. The Unsteady Vortex Lattice Method is employed to model the unsteady aerodynamics of 3-D potential flow field surrounding the wing. An UVLM computer code was then developed and validated for numerical simulation. A morphing wing which changes its dihedral angle with constant angular velocity was investigated by the code, and the lift, induced drag, and pitching moment coefficients' time histories were obtained. The results show that the UVLM code is an effective tool for simulations of unsteady aerodynamics on morphing wings. © (2013) Trans Tech Publications, Switzerland.


Yan X.-D.,Northwestern Polytechnical University | Yan X.-D.,National Key Laboratory of Aerospace Flight Dynamics | Jia X.-J.,Northwestern Polytechnical University | Lv S.,Northwestern Polytechnical University
Guti Huojian Jishu/Journal of Solid Rocket Technology | Year: 2013

Rocket based combined cycle (RBCC) powered vehicles generally climb with constant dynamic pressure at ascent stage in order to provide an optimal or steady condition for the propulsion system. An algebraic equation of height and velocity for constant dynamic pressure climbing was derived. The algebraic equation was used to plan and generate the reference trajectory. Then, a guidance law tracking the reference trajectory was derived via feedback linearization method. Based on the above, the guidance method of constant dynamic pressure climbing for ascent stage of RBCC powered vehicle was implemented. The simulation results show that the method is able to generate the command of attack angle in real-time and complete constant dynamic pressure climbing accurately. Furthermore, the method provides an ascent trajectory design and guidance method for air breathing aerospace vehicle.

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