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.

Luo J.,Northwestern Polytechnical University | Luo J.,National Key Laboratory of Aerospace Flight Dynamics | Zhou L.,Northwestern Polytechnical University | Zhou L.,National Key Laboratory of Aerospace Flight Dynamics | And 2 more authors.
Advances in Space Research | Year: 2017

This paper presents an optimal control method for consensus of satellite cluster flight under a kind of energy matching condition. Firstly, the relation between energy matching and satellite periodically bounded relative motion is analyzed, and the satellite energy matching principle is applied to configure the initial conditions. Then, period-delayed errors are adopted as state variables to establish the period-delayed errors dynamics models of a single satellite and the cluster. Next a novel satellite cluster feedback control protocol with coupling gain is designed, so that the satellite cluster periodically bounded relative motion consensus problem (period-delayed errors state consensus problem) is transformed to the stability of a set of matrices with the same low dimension. Based on the consensus region theory in the research of multi-agent system consensus issues, the coupling gain can be obtained to satisfy the requirement of consensus region and decouple the satellite cluster information topology and the feedback control gain matrix, which can be determined by Linear quadratic regulator (LQR) optimal method. This method can realize the consensus of satellite cluster period-delayed errors, leading to the consistency of semi-major axes (SMA) and the energy-matching of satellite cluster. Then satellites can emerge the global coordinative cluster behavior. Finally the feasibility and effectiveness of the present energy-matching optimal consensus for satellite cluster flight is verified through numerical simulations. © 2017 COSPAR.

Pan X.,Northwestern Polytechnical University | Pan X.,National Key Laboratory of Aerospace Flight Dynamics | Pan B.-F.,Northwestern Polytechnical University | Pan B.-F.,National Key Laboratory of Aerospace Flight Dynamics | Tang S.,Northwestern Polytechnical University
Yuhang Xuebao/Journal of Astronautics | Year: 2017

A new homotopy method is proposed to solve the fuel-optimal transfer trajectory with flyby of other celestial bodies in the deep space exploration, overcoming the difficulty due to the interior point constraints and discontinuous structure of the Bang-Bang control. The homotopic parameter is embedded in both the performance index and interior point constraint equations. By starting from a related and easier energy-optimal problem without inner constraints, and solving a series of iterative subproblems with homotopic parameter increased, the solution of the original problem is obtained when the parameter reaches one. With the approach, the difficulty of the optimization variables increased caused by the flyby inner constraints can be resolved, and the low-thrust fuel-optimal transfers can be completed effectively. At last, two examples about the Jupiter rendezvous with the Mars flyby and the Mars rendezvous with an asteroid flyby are given to substantiate the effectiveness and optimality of the homotopy method. © 2017, Editorial Dept. of JA. All right reserved.

Lyu S.,Northwestern Polytechnical University | Lyu S.,National Key Laboratory of Aerospace Flight Dynamics | Yan X.,Northwestern Polytechnical University | Yan X.,National Key Laboratory of Aerospace Flight Dynamics | And 2 more authors.
Aerospace Science and Technology | Year: 2017

A prescribed performance guidance law during the terminal homing phase is proposed to intercept a non-cooperative maneuvering target in this paper. First, on the basis of sliding mode control, a prescribed performance control method based on a revised prescribed performance function is proposed to drive the sliding mode variable to zero. It leads to smooth guidance commands to fulfill the terminal line of sight angle constraint. Then, taking the autopilot's dynamics and its uncertainties into account, a robust controller is designed using dynamic surface control, sliding mode control and inertial delay control, which guarantees the reference guidance commands to be precisely tracked. The highlights of the proposed guidance law are: 1) the transient performance of guidance commands is improved, so that excessive large changes are avoided in the initial phase, 2) parameters that dominant the convergence of the predetermined sliding mode variable can be analytically determined based on the predesigned terminal tolerance, it is more convenient to achieve the prescribed convergence, 3) although uncertainties are existing in the dynamics of missile autopilot, the proposed guidance law could guarantee the terminal interception accuracy. All of the improvements are shown in numerical simulation results. © 2017

Qiao Q.,Northwestern Polytechnical University | Qiao Q.,National Key Laboratory of Aerospace Flight Dynamics | Yuan J.,Northwestern Polytechnical University | Yuan J.,National Key Laboratory of Aerospace Flight Dynamics | And 2 more authors.
Aircraft Engineering and Aerospace Technology | Year: 2017

Purpose: The purpose of this paper is to establish the dynamics model of a Z-folded PhoneSat considering hinge friction and to investigate the influence of disturbances, such as friction, stiffness asymmetry, deployment asynchronicity and initial disturbance angular velocity, on the attitude of PhoneSat during and after deployment. Design/methodology/approach: For the Z-folded PhoneSat, the dynamics model considering hinge friction is established and the dynamics simulation is carried out. The effects of friction, stiffness asymmetry, deployment asynchronicity and initial disturbance angular velocity on the attitude motion of the PhoneSat are studied and the attitude motion regularities of the PhoneSat considering the disturbance factors mentioned above are discussed. Findings: Friction has a main contribution to reducing the oscillation of attitude motion and damping out the residual oscillation, ultimately decreasing the deployment time. An increasing length of deployment time is required with the increasing stiffness asymmetry and time difference of asynchronous deployment, which also have slight disturbances on the attitude angle and angular velocity of PhoneSat after the deployment. The initial disturbance angular velocity in the direction of deployment would be proportionally weakened after the deployment, whereas initial disturbance angular velocity in other direction induces angular velocities of other axes, which dramatically enhances the complexity of attitude control. Originality/value: The paper is a useful reference for engineering design of small satellites attitude control system. © Emerald Publishing Limited.

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.

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.

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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