Aiming at the problem of hypersonic vehicle control with strong coupling and severe nonlinearity, an improved adaptive second-order sliding mode control method is proposed.Firstly, uncertain factors are added to the longitudinal model of hypersonic vehicle, and a control model with parameter uncertainties, model uncertainties and interferences is established.Secondly, based on the established model, an adaptive second-order sliding mode controller based on super-twisting algorithm is designed by using quadratic Lyapunov function.Finally, the simulation results show that:Compared with the common second-order sliding mode controller, the controller designed in this method has better tracking effect and robustness for systems with unknown upper bound uncertainty.

To solve the problem that the eigenvectors corresponding to the mainlobe interference are difficult to distinguish in eigen-projection matrix preprocessing, a mainlobe interference suppression algorithm based on subspace orthogonality is proposed.Firstly, the prior information of rough mainlobe region is exploited to calculate the mainlobe subspace, and eigen decomposition is made to the sampling covariance matrix.Then, the orthogonality of the obtained eigenvectors of interference is tested one by one in the mainlobe subspace, and the eigenvectors corresponding to the mainlobe interference are extracted.Subsequently, the mainlobe component can be suppressed by eigen-projection matrix preprocessing.Finally, the adaptive weight vector can be calculated by covariance matrix reconstruction to cancel sidelobe interference.Simulation results validate that, the subspace orthogonality test can detect all the eigenvectors corresponding to the mainlobe interference, suppress multiple mainlobe interferences successfully, and solve the problem that the mainlobe interference suppression method based on eigen-projection matrix preprocessing and covariance matrix reconstruction can only suppress single mainlobe interference.

In order to study the detection performance of the network radar countermeasure system, the detection coverage of the three configuration models of the network radar countermeasure system was studied.Firstly, the network radar countermeasure system model was established.According to the basic radar equation, the boundary equation of the coverage of the network radar countermeasure system in active mode was derived, and active coverage of the three configuration models in omnidirectional search was simulated.The simulation results showed that: 1) The distance between the adjacent detection units determines the coverage boundary of the system under certain signal-to-noise ratio conditions; and 2) The coverage of the detection unit with a long separation distance is the basis for obtaining the diversity gain.Therefore, when configuring the network radar countermeasure system, it should be distributed as evenly as possible in the configuration area.The simulation results prove the feasibility of the method.

Underwater target detection is one of the key technologies in navigation.The previous active sonar signal simulation has the shortcomings of relatively simple target model, low degree-of-fitting of the simulated echo with the real echo, and large computation burden, which is not suitable for real-time prediction of complex target.Based on building up the models of the ocean ambient noise and the ocean reverberation, we made active sonar echo signal simulation for the ship by using highlight model.The result of pool experiment showed that, the echo reached the expected effect in comparison with the echo in experiment, which supplied a reference for test improvement of the sonar set.

In view of the great differences of different Kalman filters for SINS based integrated navigation in performance, a comparison of Kalman filters for SINS based integrated navigation was carried out.Under different filtering frameworks, the key similarities and differences of two quaternion based classical integrated navigation algorithms were studied.Through car-mounted experiment, the Euler based indirect integrated navigation filter was compared with the two quaternion based nonlinear integrated navigation filters on accuracy and calculation amount.The results showed that the Euler based integrated navigation filter has poor filtering accuracy but small calculation amount, while the quaternion based integrated navigation filters have better filtering accuracy but larger calculation amount.The results can provide a useful reference for the selection of integrated navigation filtering.

Target tracking is a hot topic in the field of computer vision and has a wide range of applications in practice.The 3D single-target tracking problem is mainly studied in this paper.Considering that the 3D target detection has good performance, the 3D target detection result obtained by using the frustum point cloud network is combined with the TLD target tracking algorithm, and the detection module of the TLD algorithm is improved.A 3D single-target tracking algorithm based on the TLD algorithm is proposed.The input is the RGB-D image sequence, and the output is the 3D tracking results of the target.The test results in the KITTI data set prove the feasibility of the algorithm in 3D target tracking.

For the class of high-order nonlinear systems with unmatched disturbances and modeling error, an Adaptive Backstepping Non-singular Terminal Sliding Mode Control (ABNTSMC) scheme based on Nonlinear Disturbance Observer (NDO) is proposed combined with filtered backstepping method.Firstly, a finite-time stable nonlinear disturbance observer is designed to estimate and compensate for the unmatched disturbances.The backstepping method is employed to deal with high-order uncertain nonlinear systems.To avoid the explosion of differentiation in traditional backstepping control, the dynamic surface control method is used to design the virtual controller.In the nth step, a non-singular terminal sliding mode controller is designed based on the adaptive control and NDO to eliminate the effects of unmatched disturbances and modeling error on the systems.It is proved that the tracking error is guaranteed to be uniformly and ultimately bounded by using Lyapunov theorem.Finally, the simulation results prove the efficacy of the proposed method.

The Polar Format Algorithm (PFA) mainly uses interpolation algorithm in the Inverse Synthetic Aperture Radar (ISAR)imaging algorithm to solve the problem of cross-range migration of scattering points.The selection of the interpolation method determines its imaging efficiency and computing speed.In this paper, an interpolation method along the line of sight of radar is proposed.The geometric model of ISAR target with large rotation angle is established, the precise interpolation form of azimuth direction is obtained by theoretical derivation, and azimuth resampling is carried out for the deformation caused by non-uniform sampling.Simulation results show that compared with the traditional interpolation algorithm, it has the advantages of faster operation speed and better focusing performance.

To solve the problems of spectral distortion and lack of spatial details in image fusion, an image-fusion approach was proposed based on the improved guided filtering and quantum genetic algorithm.Firstly, up-sampling operation was used in multi-spectral image, and the panchromatic image was fitted by the improved guided filtering.Secondly, the new panchromatic image was optimized by using quantum genetic algorithm.Next, the multi-spectral image and panchromatic image were decomposed by wavelet transform.Then, weighted average was made to the high-frequency part, and the principle of selecting the maximum-pixel was used to the low-frequency part.Finally, the fusion image was reconstructed by adopting the inverse wavelet transformation.Experimental results show that the improved method effectively increases such image indicators as average gradient and information entropy, which can enhance the details and spectral information in image fusion, and get better visual effect.

The integrated missile guidance and control technology is to design the guidance system and the control system of the missile comprehensively, which can fully exploit the overall performance of the missile and improve the hit accuracy.Taking the terminal angle constraint into consideration is a hot spot of research in the integrated design in order to enhance the damage effect.For bank to turn missile, the missile motion model and the missile-to-target relative motion model are established at first, which is the basis of the integrated research;the existing research methods are classified and summarized subsequently;and the problems and development trends of the current integrated guidance and control research are sorted out in the end.

In order to meet the needs of the combat mode of future fighter on weapon control management, the technical development of airborne Store Management System (SMS) is studied, and the technical characteristics and development trend of the new-generation airborne SMS are proposed as well.An analysis is made to the interconnection relationship between the aircraft and the stores, and a hierarchical design method is given.The key technologies of the universal armament interface,intelligent high-safety weapon control management, and coordinated control of weapons based on different platforms are all illustrated, and a design idea of the new-generation SMS is presented.

The airworthiness certification of display and crew alerting system faces challenges due to the characteristics of task crosslinking with other airborne systems and the application of new technologies such as head-up display system.In this paper, the airworthiness documentation and requirements of the display and crew alerting system are analyzed.The determination principle of certification basis and compliance methods,and the crosslinking relationship with other airborne systems on compliance verification are given.The certification elements and review requirements of display and crew alerting system are given from the perspective of actual certification.The study can provide support for airworthiness certification and development of airborne display and crew alerting system of civil aircraft.

The sensitive point of the rotating IMU does not coincide with the origin of the aircraft body coordinate system, there is angular motion in the process of the self-alignment, thus the lever-arm effect error is introduced.In this paper, analysis is made to the influence of rotating inertial navigation inner arm on the self-alignment according to the lever-arm effect error model.In order to solve the problem, a method of arm calibration combined with self-alignment process is proposed.The method does not need additional calibration process, and can be easily implemented in engineering applications.The test results show that:1) The method can accurately calibrate the inner arm of rotating IMU, with the calibration accuracy of 1.1 mm;and 2) After the compensation of the arm, the self-alignment accuracy can be significantly improved, and the azimuth alignment accuracy is improved by 35%.

Aiming at the earlier verification of the system design of the Distributed Integrated Modular Avionics (DIMA), the Architecture Analysis and Design Language (AADL) and the DIMA architecture characteristics are introduced.Taking an example of architecture design as input, models of the architecture of a DIMA system and of the inter-module communication are established.By using the models, analysis is made to the utilization ratio of the processor, and the schedulability of the partition/task, and simulation is made to the inter-module communication, which verifies the feasibility of the architecture design.

The Glide Slope (GS) uses the mirror principle to provide vertical guidance information for the aircraft in precision approach process,and terrain of the airport directly affects the vertical coverage performance of the GS.In this paper, the Antenna Distribution Unit (ADU), radiation field, Difference of Depth of Modulation (DDM) and angular displacement sensitivity of four types of GS are studied at first, and then comparison and analysis is made to the Beam Bend Potential (BBP) of different GSs.Finally, the influence of Forward Slope (FSL) on the vertical coverage performance of the GS is studied, and the corresponding compensation method is proposed.Combined with the terrain characteristics glide slope of the airport, it can provide a theoretical basis for the GS selection,installation and debugging.

The heading error of gyrocompass has a nonlinear mapping relationship with the heading angle and the device error.In this paper, a strap-down gyrocompass calibration method is proposed based on the heading effect of gyrocompass.On the basis of analyzing the propagation mechanism of heading error of gyrocompass, curve fitting is made to the heading error, and the mathematical models of heading angle and heading error is established.Thus the gyrocompass calibration is completed according to the heading error relationship.The experimental data shows that the proposed calibration method can effectively reduce the heading error and improve the accuracy of gyrocompass, which has practical application value.

In order to correct the drift of the UAV strapdown inertial navigation system and realize the construction of UAV integrated navigation system, the information fusion technology of integrated navigation scheme for UAV in approaching stage is studied.Based on the basic concept of Kalman filter method for information fusion, the models of laser range finder, electronic compass and altimeter system used to correct the drift of strapdown inertial navigation system are deduced, and then the model of the aviation information fusion subsystem for UAV integrated navigation is built.A multi-rate Kalman filtering system based on indirect parameter estimation is constructed.The simulation of UAV integrated navigation information fusion system is realized by building a mathematical model with Matlab, and the feasibility of the information fusion scheme is verified.

In traditional test system, the evaluation of the performance of the missile control system is too rough and inaccurate, thus it is proposed to use the membership function to refine the performance status level.By using the improved D-S evidence theory, the problem of mistakes arisen when fusing the high-conflict evidences is solved, comprehensive analysis is made to the dynamic and static data of the closed-loop simulated test of the control system, and the performance status levels of the key nodes and the whole process during the simulated flight are obtained, according to which the test and maintenance cycle can be adjusted.The simulation verifies the feasibility of the method.

Random Sample Consensus (RANSAC) algorithm is widely used in the field of image matching, which helps the image matching algorithm to filter and eliminate mismatched pairs and improve the accuracy of image matching.The classical RANSAC algorithm has the problems such as large amount of computation, slow operation speed, and poor sample adaptability, which cannot meet the requirements on real-time performance and sample variability in image matching.Aiming at the above problems, an improved RANSAC algorithm is proposed based on adaptive pre-test and adaptive iterative threshold,and the working principles are given.The experimental results show that the proposed algorithm has a significant improvement in computation speed and sample adaptability compared with the classical RANSAC algorithm.

Aircraft Battle Damage Repair (ABDR) is the best way for the battle-scarred aircrafts to fly again.The ABDR time assessment is very important for evaluating the battle damage degree of the aircraft, and is also a main precondition for making urgent repair.Considering that the ABDR time assessment is influenced by many factors, the Principal Components Analysis (PCA) method is used for dimension reduction, which transformed the large number of influence factors into uncorrelated new variables, known as principal components, which are linear combinations of the original variables.The achieved principal components are explained from a new insight.A multiple linear regression model is built for assessing ABDR time.The regressive parameters of the model are optimized through Genetic Algorithm (GA).The following results are obtained by using PCA method:1) The 12 ABDR time assessment influence factors are reduced to 6 new principal components, which decreases the input numbers and complexity of the regression model effectively;and 2) The error of ABDR time evaluated by the optimized regression model is smaller, with an average relative error of 12.82%.

Compared with traditional DMD digital display, MEMS laser scanning display has the advantages of high contrast and no background halo.However, the single fine laser beam emits light at a very small angle, which needs to be extended, and the speckle caused by laser coherence should also be eliminated to improve the display quality.The structural design of a random microlens array extended screen for laser scanning display was put forward based on 2DR-SPP algorithm.The laser direct writing hot melting technology was developed to realize the accurate production of the laser scanning extended screen.Finally, the extended screen of laser scanning display with speckle eliminated was obtained, which has a divergence angle of above 70°, a relative uniformity of luminance of above 70%, and an efficiency of energy utilization of above 90%.The extended screen can be used in laser scanning display systems onboard the aircrafts and ground vehicles.

The establishment of accurate and intelligent real-time onboard diagnostic models is essential for improving the reliability and safety of weapon system.Aiming at the limitations of the existing diagnostic model development methods, a new method for developing the onboard diagnostic models is proposed.By use of the graphical modelling approach and based on the data of the system or onboard equipment, the implementation procedures for the model development are introduced, including data preparation, system model extraction, fault characteristic matrix construction, and diagnosis reasoning.Taking the model development process and diagnosis results of a certain type of fuel tank as an example, it is verified that the real-time onboard diagnostic model based on system data analysis has high detection rate, high isolation rate and high accuracy.

Optical phased array technology has the advantages of fast scanning speed, high scanning precision and high sensitivity, but the existence of grating lobes largely limits its characteristics.An optimized unequal spacing method is proposed for beam scanning control of optical phased arrays.The effects of optical phased arrays with unequal element spacing on grating lobe suppression are analyzed.The minimum Peak Side-Lobe Level (PSLL) is obtained by optimizing the spacing of adjacent elements by an improved particle swarm optimization algorithm.The data simulation of the one-dimensional optical phased array shows that, optimizing the element distribution with the improved particle swarm optimization algorithm can suppress the grating lobes well,and the PSLL can be as low as 0.2 or less.