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Aiming at the attitude control of an asymmetric morphing-wing aircraft, a compound control system is proposed. Based on the dynamic model of the asymmetric morphing-wing aircraft, the morphing wing is regarded as a new active control mechanism and the condition of using the asymmetric morphing wing is determined. A control strategy for the allocation of the control commands is designed by the logic function. The disturbance caused by the morphing wing is estimated by the extended disturbance observer and the variable structure control method with global sliding mode is used to design the compound control system which restrains the violent changes in parameters and disturbance during the process of morphing. According to the simulation, compared to the fixed-wing aircraft, the effectiveness of the asymmetric morphing wing is assessed and the robustness of the controller is also evaluated by the pertubation of the parameters. [ABSTRACT FROM AUTHOR]

The observability problem of binocular vision measurement system in spacecraft relative navigation is studied in this paper. The Fisher information matrix of system estimation is derived and the method for observability analysis based on the rank analysis of Fisher information matrix is proposed. The interrelationships among the number and distribution of characteristic points, the rank of Fisher information matrix, and the system observability are studied. The conclusion is that at least 2 characteristic points are needed to insure the fully observation. At last, the observabilities of both monocular vision and binocular vision measurement system are compared according to differences of measurement equations under the same number of characteristic points. Simulation results of position and attitude determination for single picture confirm the conclusion obtained from the rank analysis of the Fisher information matrix. [ABSTRACT FROM AUTHOR]

This paper presents a novel coupling characterization based robust control scheme for hypersonic vehicles. First of all, the attitude equations of a hypersonic vehicle are denoted, and the error dynamic model of the hypersonic vehicle is obtained based on the backstepping technique. Then, a robust coupling-based control scheme is proposed combining with the disturbance observer, and the asymptotic convergence is guaranteed through the sliding mode compensation. Finally, the integral absolute error (IAE) performance index is introduced, and the better performance of the proposed method is proven theoretically. The proposed method not only guarantees the asymptotic stability and the strong robustness, but also improves the dynamic performance via considering the coupling characterization into the controller design. The aerodynamic parameters perturbation and actual actuator constraints are considered in the numerical simulations, and the results demonstrate the validity of the control method in this paper. [ABSTRACT FROM AUTHOR]

Based on drag acceleration profile, a predictor-corrector guidance law which can guide longitudinal motion and lateral motion synergistically is proposed in this paper. The drag acceleration profile is designed through interpolating between upper drag boundary and lower drag boundary, and then corrected to eliminate the range error. The altitude error is eliminated by adjusting attack angle. The lateral error is eliminated by regulating the reversal time of bank angle. Comparing with the traditional methods, the proposed one can correct the 3-dimensional motion of the vehicle. Using interpolated drag acceleration profile, the flight constraints can be easily dealt with. Moreover, in a correction cycle, the method in this paper only needs twice trajectory predictions, which is favorable for on-board calculation. The simulation results indicate that the proposed guidance law has a high precision and robustness. [ABSTRACT FROM AUTHOR]

Two typical flight modes of hypersonic glide vehicles, equilibrium glide and skip glide, are researched in the paper. Firstly longitudinal kinematic models for hypersonic glide vehicle are established. Relative functions between velocity, height and fight path angle are deduced, and the changing laws of dynamic pressure, total load factor and heating rate with velocity are analyzed in the equilibrium glide mode. In addition, analytical equations between state parameters are presented under the condition of constant lift-drag-ratios. Numerical simulation method is applied to explain the effect of the initial parameters on the skip glide trajectory. The study can help improve the understanding and provide guidance for missions like trajectory prediction, planning and guidance. [ABSTRACT FROM AUTHOR]

On-line trajectory plan methods are of no guarantee of real time for using optimization searching algorithms. They are unpractical to be adopted in engineering application for reusable launch vehicles (RLV) in terminal area energy management (TAEM). An prediction and acquisition straight line (PASL) phase is added before the heading alignment cone (HAC) to accomplish the TAEM trajectory on-line planning in advance, thus decreasing the requirement for the real time performance. The vehicle's initial states of the TAEM phase referred to as the terminal states of the PASL phase can be predicted by calculating the analytic solution of three-degree freedom motion equations with zero aerodynamic angle. Taking dynamic pressure, normal acceleration and bank angle as constraints, it is transformed into a non-linear planning problem to generate the TAEM trajectory. The objective function is to search for the optimal HAC position with a minimum heading error to enter the HAC. In addition, a pneumatic-angle directive (PD) feedback tracking law is designed, where the open-loop commands are available once the trajectory is obtained. Finally, an illustrative example is given to confirm the efficiency of the TAEM method based on trajectory prediction. [ABSTRACT FROM AUTHOR]

A new kind of robust adaptive control method is proposed for hypersonic vehicle with strong coupled characteristics and modeling uncertainties. Firstly, based on the founded dynamic model of hypersonic vehicle, the new coupling mathematical model with non-matched characteristics by introducing expected reference model. Secondly, the robust adaptive control strategy is derived by dynamical timely adjusting parameters and utilizing the solution of the Riccati equation. Finally, an illustrative example is given to show the proposed control scheme can guarantee the stability of the hypersonic vehicle under the condition of large-scale variation of model parameter perturbation and disturbance. [ABSTRACT FROM AUTHOR]

A mobile satellite communication system is installed on a moving carrier for satellite communication. The tracking and stabilizing problem of the mobile satellite communication system is studied in this paper. The tri-axis nonlinear model of the mobile satellite communication system is chosen as the control object, because it can describe the kinematics and dynamics features of the system more accurately than the single-axis model. Based on the actuator dynamic features, a nonlinear robust controller with actuator dynamic compensation is designed. The designed controller can eliminate the disturbances when the carrier is moving and track the target satellite accurately. Because the problem of the actuator dynamics is further considered, the controller is more suitable for the practical application. At last, three sets of comparative simulation results are used to verify the tracking and stabilizing effectiveness of the designed controller under different disturbances. [ABSTRACT FROM AUTHOR]

Double Lunar-Swingby (DLS) trajeclories have received much attention due to its wide applications in the trajectory design of Multi-Mission and Multi-Purpose'. First, the DLS orbits are divided into two classes named Plane type and Backflip type according to their space configuration and characteristics. Then, the basic theory of swingby is shown based on two dynamics models of Zero-Sphere-of-Influence and CR3BP. Furthermore, both dynamics and modeling of Plane type DLS trajectory are discussed in two categories of application, and the principle and solution methods of Backflip type orbit is also summarized in detail. This study and survey about DLS trajectories could provide a new insight and reference for the interplanetary' mission of China. [ABSTRACT FROM AUTHOR]

A liquid propellant gauging method named Compression Mass Gauge (CMG) with high accuracy 1s studied in this paper. Firstly, the theory of CMG and the ground test board system are introduced. The test system is composed of the compression construction, coder motor, data collection and processing subsystems. Then a test scheme is proposed. All tests are conducted under normal temperature and pressure and different excitation frequencies are selected. Finally, ground simulation tests are implemented and results are obtained. The results indicate that CMG measurement errors in different filling levels are less than 1% of the total tank volume. It is hoped that the present study can contribute to the liquid propellant gauge with high accuracy in future flight test and aerospace application. [ABSTRACT FROM AUTHOR]