A full-state nominal trajectory tracking guidance scheme, in which the optimal feedback control law is solved by indirect Radau pseudospectral method, for hypersonic vehicle gliding guidance is proposed. Based on the Pontryagin maximum principle, the state regulator problem for a linear time-varying system converted from the original trajectory tracking problem is transformed into the linear two point boundary value problem. The indirect Radau pseudospectral method is applied to solve the obtained linear two point boundary value problem, and the closed-loop trajectory tracking guidance law easily implemented online is designed on the basis of the resulting optimal feedback control law. Simulation results indicate that the proposed guidance scheme is robust to the presence of large initial state deviations and limited flight environment parameter disturbances, and satisfies real-time requirement.
Yu Xin Liao;Hui Feng Li;为民 包
Yuhang Xuebao/Journal of Astronautics
The maximum-crossrange problem is difficult to solve rapidly and stably because of highly nonlinear dynamics and nonconvex constraints. In this paper, an improved successive second-cone programming method via the pole-transformation process is proposed. The main contribution of this work is twofold. Firstly, the pole-transformation coordinate frame is defined, and the original problem is reformulated by the pole-transformation process to avoid the linearization of downrange and crossrange angles. The terminal state constraint is relaxed to an inequality constraint, which improves the stability performance of the solution method. Secondly, an adaptively adjustment method of the trust-region contraction coefficient is proposed to improve the convergence performance of the solution method. The optimal solution of the original problem is obtained by the improved successive second-order cone programming method. The numerical experiments verify the effectiveness of the pole-transformation process, and the convergence and stability performances of the improved solution method proposed in this paper.
Xiang Zhou;Hong Bo Zhang;Lei Xie;Guo Jian Tang;为民 包
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
A new entry trajectory generation approach based on rapid planning three-dimensional acceleration profile (TDAP) is proposed in this paper. The TDAP planner concept means extending the traditional drag planning approach into three dimensional drag space to accommodate much larger downrange or cross-range, and improve the maneuvering capability by utilizing both angle of attack and bank as primary control commands. To figure out this problem, firstly, the planner transforms the generation of TDAP into scheming two sub-profiles, longitudinal drag acceleration profile and lateral lift to drag acceleration profile in parallel. Each profile is generated in the corridor converted by all path constraints correspondingly. Secondly, a reduced order dynamics system is employed to extract all standard state variables and adjust the three-dimensional acceleration profile, ensuring the terminal position precision requirement to be met. Finally, a combined proportional derivative (PD) feedback law is designed to track the reference profile. Simulations with the Common Aero Vehicle (CAV) model show that the 3-D trajectories of both planned and generated by the guidance law can successfully satisfy all path constraints and flight task requirements.
Yuan Long Zhang;Ke Jun Chen;Lu Hua Liu;Guo Jian Tang;为民 包
Aerospace Science and Technology
With the rapid development of the artificial intelligence technology, significant breakthroughs in its theory and applications have been widely used in many fields. The related theories and technical achievements of artificial intelligence are likely to be integrated to the maximum extent in the field of control; that is, intelligent control will become the comprehensive embodiment of the artificial technology. This study starts with an overview of the development of the control science and technology, and concludes that intelligent control will become a starting point for the integration of artificial intelligence and industry. Then, the study discusses the development requirements of intelligent control, ways of control technology intellectualization, development stages of intelligent control, and characteristics of each stage. Finally, the key direction of promoting the development of the intelligent control technology is described.
为民 包;Zhenqiang Qi;Yu Zhang
Scientia Sinica Informationis
This paper develops a timing solution for the X-ray pulsar timing model without the use of the initial radio model parameters. First, we address the problem of phase ambiguities for the pre-fit residuals in the construction of pulsar timing model. To improve the estimation accuracy of the pulse time of arrival (TOA), we have deduced the general form of test statistics in Fourier transform, and discussed their estimation performances. Meanwhile, a fast maximum likelihood (FML) technique is presented to estimate the pulse TOA, which outperforms cross correlation (CC) estimator and exhibits a performance comparable with maximum likelihood (ML) estimator in spite of a much less reduced computational complexity. Depending on the strategy of the difference minimum of pre-fit residuals, we present an effective forced phase-connected technique to achieve initial model parameters. Then, we use the observations with the Rossi X-Ray Timing Explorer (RXTE) and X-ray pulsar navigation-I (XPNAV-1) satellites for experimental studies, and discuss main differences for the root mean square (RMS) residuals calculated with the X-ray and radio ephemerides. Finally, a chi-square value (CSV) of pulse profiles is presented as a complementary indicator to the RMS residuals for evaluating the model parameters. The results show that the proposed timing solution is valid and effective, and the obtained model parameters can be a reasonable alternative to the radio ephemeris.
Hai feng Sun;Xiong Sun;Hai yan Fang;Li rong Shen;Shao peng Cong;彦明 刘;小平 李;为民 包
High-quality GaN film is grown on graphene with the underneath sputtered AlN modified layer using metal organic chemical vapor deposition. Due to the modulation effect of sputtered AlN on the surface potential and the chemical reactivity of graphene, the nucleation probability of GaN is significantly improved. The GaN epitaxial layer shows excellent crystal quality and surface morphology, and has very low threading dislocation density of 1.78 × 108 cm−2. Furthermore, the mechanism of threading dislocation suppression is revealed according to the transmission electron microscope results. The improved nucleation probability and enhanced lateral growth mode lead to the formation of short-range stacking faults in c-plane GaN, which block the propagation of threading dislocations along the growth direction. Moreover, the formation and evolution mechanism of the short-range stacking faults are discussed. The results in this work not only offer a promising approach to propel the widespread application of GaN on graphene, but also provide a new idea for the regulation and suppression of defects in the growth of nitride semiconductors.
Yachao Zhang;Kai Su;Rui Guo;Shengrui Xu;Dazheng Chen;Jiaduo Zhu;为民 包;进成 张;Jing Ning;跃 郝
Physica Status Solidi - Rapid Research Letters
In this paper, a planning approach of maneuver trajectory based on dynamic inversion is proposed, which can greatly improve the penetrability of hypersonic glide vehicles in dive phase. Maeuvering and guiding overloads are combined using a weight coefficient, which is designed as the function of altitude. Enough adjust ability is guranteed at the end of dive phase, and more complex maneuver trajectories are achieved. Firstly, four different modes of maneuver trajectories are realized by coordinating the maneuver in longitudinal and lateral sub-planes, respectively. Dynamic inversion is employed to establish the relationship between the designed trajectory and the needed overload. Secondly, the minimum energy loss is selected as the optimization index, and the optimal overload is obtained based on the maximum principle. the final path angle constraint is also considered in this algorithm. Finally, the maneuvering and guiding overloads are combined using a weight coefficient, and the corresponding angle of attack and bank are obtained. The approach is tested using common aero vehicle-H (CAV-H) model, and the results demonstrate that the method proposed in this paper can realize the maneuver trajectory in dive phase with high terminal accuracy and strong penetration ability.
Ruizhi He;Luhua Liu;Guojian Tang;为民 包
In order to achieve hit-to-kill in terms of intercepting the hypersonic glide vehicle, the first task is to accurately track the flight state and predict the trajectory. In this paper, a radar tracking approach for hypersonic glide vehicles is proposed based on a novel aerodynamic model. The extended motion equations are derived on basis of the established aerodynamic acceleration, and the measurement equations of radar are given. In view of the nonlinearities, the extended and unscented Kalman filters are adopted to estimate the extended state, respectively. To examine the proposed method, two types of standard trajectories are designed and then tracked. Simulation results indicate that it can precisely track the hypersonic glide vehicle, which provides a guarantee of the following trajectory prediction.
Jingshuai Huang;Hongbo Zhang;Guojian Tang;为民 包
Compressive sensing (CS) has been widely used in vehicular technology including compressive spectrum sensing, sparse channel estimation, and vehicular communications. The complete procedure of CS consists of sparse representation, sparse measurement, and sparse recovery. In the CS, measurement matrix Φ is utilized to sample a sparse signal, while sensing matrix Ψ is exploited for sparse recovery. It is important to properly design the sensing matrix that significantly affects the signal recovery performance. This paper addresses the issue of the sensing matrix design for the CS with multiple measurement vectors (MMV). We first study sufficient conditions for the MMV-CS and then develop three sensing matrix design approaches in different situations. The proposed methods have their roots in the principle of minimum variance distortionless response (MVDR) beamformer. This allows us to optimally determine the sensing matrix in the framework of the MVDR, which amounts to minimizing local cumulative cross-coherence between Φ and Ψ while keeping the columns of Ψ highly correlated to their counterparts of Φ. Simulation results are presented to verify the effectiveness of the proposed methods.
Liang Zhang;Lei Huang;Bo Li;敬伟 殷;为民 包
IEEE Transactions on Vehicular Technology
In terms of intercepting endoatmospheric maneuvering targets, a differential geometric guidance law is designed based on a generalized differential geometric guidance scheme. Different from forcing the line of sight rate to converge to zero in finite time, a sliding surface is adopted where the line of sight rate asymptotically converges to zero as the relative distance between the missile and the target decreases. Considering the peaking phenomenon of observer estimating target acceleration in the initial stage and the stability difficult to prove for observer-embedded guidance laws, target acceleration is regarded as a disturbance with unknown bound and a double-power adaptive law is proposed to estimate the bound. A modification term is used to eliminate the influence on stability of saturation function replacing sign function and the asymptotic stability of the proposed guidance law is guaranteed by stability analysis. Simulation results indicate that the designed differential geometric guidance law is able to effectively intercept maneuvering targets. In addition, the overload distribution is reasonable and the less energy consumption is required.
Jingshuai Huang;Hongbo Zhang;Guojian Tang;为民 包
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics