In order to solve such problems as channel congestion and data collision in the wireless communication network during the process of position and attitude estimation of clustered UAVs, a distributed fusion estimator with bandwidth limitation is proposed.With a given component selection matrix and a given weight matrix, and by using the dimension reduction strategy of transporting partial estimated values of intermediate nodes, an optimization scheme is established, which takes filter gains as decision variables and the sum of the trace of the covariance matrix of the state estimation error for all UAVs in the finite time domain as the cost function.Then, a set of sub-optimal filter gain is obtained by minimizing the upper bound of the cost function, and the recursive estimation of position and attitude of the clustered UAVs is realized.Simulation results show that: 1) The distributed fusion estimation can track the true value of the state well;2) The component selection matrix and the weight matrix may affect the fusion estimation accuracy, and the optimum fusion estimation accuracy can be obtained by selecting the combination of the component selection matrix;and 3) The more uniform the intermediate state estimation is, the higher the fusion estimation accuracy.

It‘s difficult for fixed-wing Miniature Air Vehicles (MAV) in the unknown environment to avoid collision reactively when facing continuous obstacles such as the wall.To solve the problem, a MAV control method for obstacle avoidance is proposed, which combines multi-power reaching law of sliding mode control with super-twisting disturbance observer.First, the mathematical model of MAV collision avoidance system is established by using the spatial relationship and the MAV kinematics equation.Then, the guidance law of MAV collision avoidance is designed by using the characteristics of fast convergence of multi-power reaching law of sliding mode control.As to the uncertainty caused by sensor errors and system modeling errors, the super-twisting disturbance observer is introduced to compensate for the uncertainty.The convergence of the system is proved.Simulation results show that the proposed control method for collision avoidance enables the MAV to quickly avoid continuous obstacles, and has strong robustness to sensor disturbance.

The Global Navigation Satellite System (GNSS) provides global, accurate and real-time positioning information, which has profoundly changed peoples lives.However, the spoofing attack on GNSS seriously endangers the system, so it is urgent to study anti-spoofing technology.In this paper, a spoofing detection algorithm based on the position vector matrix of multiple receivers is proposed by using the Singular Value Decomposition (SVD) method.The position vector of the multiple receivers is employed to construct the spoofing detection matrix.Then, by using the SVD method, the detection matrix is decomposed into a form in which three matrices are multiplied.One of the matrices is a diagonal matrix, in which the values are zero except those on the diagonal.The singular value of the diagonal matrix is used to determine whether there is spoofing attack.The detection matrix constructed here uses the position information in the geocentric body-fixed coordinate system.The experiment results show that: when there is spoofing attack, 80% of the sum of the square of the singular values is concentrated in the first three singular values;when there is no spoofing attack, the singular values distributes evenly.This difference can be employed for accurately detecting whether there is spoofing interference.

Sea targets are usually large-sized ships or work platforms with large volume and low speed, thus the non-guided aviation bomb is a weapon with high performance cost ratio for attacking them. Previous studies on Continuously Computed Release PointCCRP)are mostly focused on fixed target bombing. There is very few research on moving target attacking. This paper proposes an improved CCRP method for target bombing. Simulation result shows that this method can effectively achieve the goal of bombing slowly moving sea targets.

When the pulsar signal is denoised by using wavelet transform, the selection of wavelet basis and decomposition layer and the construction of the threshold function have a great effect on the accuracy of pulsar navigation.In this paper, the subordination relationship between the wavelet basis and the wavelet decomposition coefficient is studied firstly, and then the reasonable wavelet basis and decomposition layer are screened according to the cross correlation between the wavelet decomposition coefficient and the original signal.During the study of wavelet decomposition coefficients, it is found that the wavelet coefficients formed by noise decrease with the increase of the decomposition layer.Based on this feature, a threshold function based on the decomposition layer is constructed.The experimental results show that, compared with the traditional wavelet-domain denoising method, the proposed method can not only accurately select the optimal wavelet basis and the optimal decomposition layer, but also effectively improve the Signal-to-Noise Ratio (SNR), Peak Signal-to-Noise Ratio (PSNR) and decrease the Error of Peak Position (EPP) of the pulsar signal after denoising with our threshold function.The study provides a new idea for the denoising of pulsar signals.

In order to improve the positioning accuracy in the precise strike of targets on the opposite shore by using the remote large-caliber naval guns, an analysis is made to the characteristics of the target positioning error based on the airborne lidar system.Firstly, the target positioning process based on the airborne lidar is given, and the target positioning model is established.Then, all the error sources that affect the target positioning accuracy are analyzed, and the model analyzing the characteristics of the error based on Monte Carlo method is established.Finally, through numerical simulation, the influence of error source on the target positioning accuracy is quantitatively analyzed, and the measures to improve the target positioning accuracy are proposed.The study provides a reference for the improvement of positioning accuracy in the precise strike of targets on the opposite shore by using the remote large-caliber naval guns.

The study focuses on air defense and anti-missile combat on the island, and takes the requirement analysis of “soft resistance” equipment system of systems for electronic countermeasure in air defense and anti-missile combat on the island as the input.By using TD-CAP software, the methods and steps of constructing the architecture model of equipment system of systems are proposed based on the Department of Defense Architecture Framework (DoDAF) standard.Some of the models describing the equipment system of systems from the perspectives of operation and the whole system are selected, and a relatively comprehensive and intuitive top-level conceptual framework of the equipment system of systems for electronic countermeasure in air defense and anti-missile combat on the island is given.Through the verification and evaluation analysis of the architecture, the integrity and consistency of the architecture are verified.The study can serve as a reference for future operations and equipment development of electronic countermeasure in air defense and anti-missile combat on the island.

In order to solve the problems of target search and map navigation under the circumstance of unknown environment and unknown target orientation, a method of dual robot collaborative exploration is proposed.Firstly, the first mobile robot uses the wall-touching algorithm to search for the target autonomously.The improved RBPF-SLAM algorithm and the Hector-SLAM algorithm are utilized to construct the map of the unknown environment respectively, and then the algorithm more suitable for the search task is selected by comparing the results and time spent on building a map.Next, the second robot reads the map from the first robot and moves along the optimal path planned by using the A* algorithm to the target point.Meanwhile, the dynamic window approach is used for dynamic local path planning for the damage area which may change at any time.Finally, simulation experiment is carried out and the practicability and effectiveness of this method are verified.

To solve the problem that the single-frequency ground-based augmentation system cannot meet the requirements of precision approach and landing navigation of aircraft category III, a navigation mode which tightly integrates airborne Differential GPS (DGPS) with Strapdown Inertial Navigation System (SINS) is proposed, and SINS is used to improve the navigation characteristics of the integrated navigation system.The tightly integrated SINS/DGPS filtering model is analyzed, and the state equation and measurement equation of tightly integrated navigation are constructed.The filtering states are estimated and compensated by using the improved Kalman filter.Computer simulation and actual system validation experiments are carried out.The experiment results show that when the satellite signal is not available in SINS/DGPS integrated navigation system, the autonomy of SINS can improve the continuity and availability of the navigation system.Meanwhile, the standard deviation of position error of the integrated navigation system is reduced by more than 50% compared with that of the single airborne DGPS system, and the position guidance accuracy of the navigation system is improved.

In recent years, rapid expansion of scale and increase of complexity of the avionics system bring higher demands on fault tolerance and reliability of Time-Triggered (TT) network.As an important technology of fault management, reconfiguration can improve fault tolerance and reliability of a specific system, and prolong its lifespan as well.In this paper, based on the reconfiguration strategy of application migration and according to different resource constraints in the avionics time-triggered network, three kinds of reconfiguration methods are proposed, namely, migration, preemption and degradation, so as to tackle the problem of application failure of the end system due to modular failure.Whats more, the relation between applications and messages in TT network is established, and a message scheduling algorithm based on Satisfiability Modulo Theories (SMT) is proposed, which can support fault recovery of the end system.The case study based on the real-time test shows that the proposed reconfiguration strategies are reasonable.

The resilience of network structure of the command information system is studied in this paper.Firstly, the definition of resilience of network structure of the command information system is proposed, and the whole process of resilience is analyzed.Then, the research points of the resilience of network structure of the command information system is given, which include resilience measurement, resilience optimization and resilience management.Finally, the research objects and preliminary research ideas of these three research points are presented in detail.The research provides a reference for the study of resilience of network structure of the command information system.

The time-reversal electromagnetic waves have the characteristics of adaptive spatio-temporal focusing and super-resolution focusing in the near field and the far field.These characteristics enable the time-reversal electromagnetic waves to have great application prospects in super-resolution imaging, high-precision positioning, low-energy secure communication and so on.The research status of time reversal technology is summarized.In view of the development trend of electronic warfare, the technical advantages and application prospects of time-reversal electromagnetic waves in electronic countermeasure are analyzed, and the research emphasis in the next step is proposed.

The paper focuses on the engineering practice of carrier aircraft recovery, and proposes a recovery strategy of carrier aircraft, which takes security as the primary constraint and practicality as the main objective.To achieve this, a recovery strategy of carrier aircraft based on saturation of the queue which first bolts and then waves off and a time interval set algorithm based on priority are combined.First, in view of the safety of the carrier aircraft formation, the optimal recovery mode is obtained.Then, by using the time interval set algorithm which considers the priority of individual carrier aircraft, different random factors are normalized to the time interval set with priority.Finally, all the carrier aircrafts are mapped into the optimal recovery mode to establish the final recovery sequence.Furthermore, based on theoretical analysis, the design of an equipment-oriented decision-making demonstration system for carrier aircraft recovery is completed on the platform of ACoreOS EOS.Experimental results indicate that, under the premise of recovery safety, the designed recovery strategy of carrier aircraft can implement the task effectively.

In order to create an accurate and stable two-dimensional acceleration overload environment for the test pieces and improve the control precision of the turntable tracking test system, the vector turntable is modeled.The PID controller based on the RBF neural network optimized by the adaptive chaotic ant colony algorithm is used, to solve the problem that the optimization of the weight of the RBF neural network is very slow, to effectively shorten the learning process of the neural network, and to improve the online adaptive ability of the PID controller, thus to enable the turntable tracking test system to rapidly track the target.The simulation results show that the PID controller based on the RBF neural network optimized by the adaptive chaotic ant colony algorithm is superior to that based on the traditional RBF neural network, and has satisfying accuracy and rapidity.It has great engineering significance for the design of the turntable tracking test system.

As the timing data of local clock of the end system, the local time of the AFDX end system can be used to calculate the transmission delay of data frame between the transmitting end system and the receiving end system, thereby performing the verification of time integrity of the transmitted data frame.If the local time of the end system is lost, the verification of time integrity of the data cannot be performed.Based on the current health management of AFDX network and the design of time synchronization, a scheme of local time recovery based on the time stamp list is proposed.It has been verified that the recovery of local time of the end system can be realized, which can further ensure the verification of time integrity of the transmitted data in AFDX network and improve the reliability of the transmitted data.

The nonreciprocal thermal rotation rate error (shupe error) produced by the fiber coil in the changing temperature field is simulated and analyzed, and a new method for winding of the fiber coil is proposed to reduce the shupe error.Firstly, the finite element models of the fiber coil with skeletons are established respectively with three kinds of symmetrical winding methods, and the same uniform temperature field load varying with time is applied to the three models.After analysis and calculation, the temperature change rate of each turn in the fiber coil is obtained.Then, the shupe error of the fiber coil under the three winding methods is calculated respectively by using the mathematical model of the thermal rotation rate error of the fiber coil, which is accurate on the turn level.The simulation results show that the shupe error is best suppressed by using the new reverse-crossing symmetrical winding method.

To solve the problem that manual intervention is required in the design of the classifier of the decision tree in radar jamming signal recognition, a method for automatic design of the decision tree based on fuzzy clustering, Xie-Beni index and information gain is proposed.Firstly, the feature set of the parameters of the jamming signal in such dimensions as the time domain, the frequency domain and the time domain after pulse compression is established.Then, Fuzzy C-Means (FCM) clustering is introduced in the process of decision tree establishment, so as to solve the problem that the traditional decision tree needs prior knowledge to set the decision threshold.Then, Xie-Beni index is used to dynamically determine the number of branches of decision tree nodes and lower the complexity of the decision tree.Finally, the ID3 algorithm based on information gain is used to establish the fuzzy-clustering decision tree.This method realizes the automatic design of the decision tree in jamming signal recognition and optimizes the performance of the decision tree.Computer simulation and the experimental data of radar countermeasure have verified the effectiveness of this method.

The purpose of this paper is to solve the problem that the naval gun can't detect the miss distance of the marine target in real time, to improve the methods of the naval gun's shooting observation and shooting correction for marine targets, and to enhance the ability of the naval gun in real combat.Firstly, based on aerial photogrammetry and the UAV's target positioning technology, the dual UAV model for simultaneous positioning of targets and burst points on the photovoltaic platform is deduced by constructing the model of the geometric relationship between the target, the burst point and the image point in the imaging space and by using the least squares method.Secondly, considering the latitude and longitude information of the naval ship, the miss distance between the burst point and the target is calculated by using the Gaussian average quotation inversion formula.Finally, the miss distance detection model is simulated by using Monte Carlo method and its error characteristics are analyzed.

A method for evaluating the quality of the filter algorithm for integrated navigation based on the projecting pursuit theory is proposed, which fuses multiple capability indexes, so as to overcome the disadvantage of only using a single capability index in evaluating the quality of the filter algorithm.Firstly, the capability indexes such as precision, real-time performance, stability and reliability of the filter algorithm are defined.Then, the quality evaluating model of the filter algorithm based on projecting pursuit is established, the optimal projection direction is solved by using the genetic algorithm, and then the comprehensive evaluating index is given.Finally, simulation tests are carried out, in which the adaptive filter is compared with the general Kalman filter, and the results indicate that the proposed method is valid in evaluating the quality of the filter algorithm.

An optical system of IR/SAL/MMW band with common aperture is designed to enable the missile all-weather operational capability and anti-interference abilities.The overall layout of the common-aperture optical system is determined by calculating the design parameters.All the three bands are reflected by the primary mirror.IR band and SAL band are reflected by the secondary mirror, while MMW band transmits through it.As to LWIR mode, the optical system designed by using passive athermalization technology performs very well, even when it is exposed to extreme temperatures.As to SAL mode, after the defocusing of the detector, the simulation result of the laser spot with field-of-view in the linear region is obtained, which is suitable for the four quadrant detector.As to MMW mode, after the optimization of the back surface of the secondary mirror, the intensity distribution of the far field is calculated, and the deduced half-power beam angle and side-lobe level conform to the design requirements.The common-aperture IR/SAL/MMW system can be applied to multi-mode combined-guidance weapons, which well adjusts to various targets in bad environment, and improves the combat capability.

The accuracy of sliding beam indication is an important indicator of the Fresnel Lens Optical Landing System (FLOLS).In response to the requirements of dynamic flight inspection of FLOLS, the overall requirements to the UAV calibration platform are analyzed from the perspectives of the influence distance and angle measurement accuracy of the calibration system and the imaging performance of the photoelectric platform.The basic composition, calibration process, calibration data processing and error analysis of the UAV calibration system are introduced.Finally, the key technologies and solutions of calibration are analyzed.The study shows that the calibration method based on the UAV differential GNSS technology meets the requirements of regular calibration of FLOLS, and has the advantages of high flexibility and high organizational implementation efficiency.

In order to improve the fidelity and intuitiveness of the test and verification of the Ground Pro-ximity Warning System (GPWS), an overall technical solution of the test platform based on 3D scene and flight simulation for GPWS is proposed based on deep analysis of the principle and verification requirements of the GPWS.Considering the aircraft characteristics and real-time factors, a realistic flight simulation model is established, and the 3D alarm envelope is visualized by using the synthetic view.The GPWS function and performance test evaluation method is proposed, which can provide a comprehensive test for GPWS equipment and algorithms.