The multi-system weapon assignment of Low,Slow,and Small (LSS) targets is studied.Aiming at the shortcomings of the traditional model when applied in real combat scene,the limiting factors of laser, radio and flexible network weapons in intercepting LSS targets are analyzed,the constraints in space,time,resources and environment are deduced,and the weapon interception weight factor is introduced in an optimized multi-system weapon assignment model for LSS target.Genetic algorithm is employed to solve the model.Finally,through the simulation and comparing the calculation results with that of the traditional model, it is verified that the optimization model established in this paper has higher calculation efficiency,and the assignment result obtained is more feasible and reasonable,which can provide a better solution for the research of multi-system weapon assignment research.

In bearings-only localization,the target position is obtained from the point of intersection of bearing lines emanating from two or more observer positions.However,the measurement equation is nonlinear,and the actual noise is difficult to be modeled accurately.To solve the problem,a direction cross target location filtering equation is constructed,and an algorithm combining smooth variable structure with Kalman filtering is proposed based on switching gain strategy.On this basis,the residual adaptive algorithm is used to further improve the accuracy of the combined filter,which effectively improves the accuracy of target locating and the robustness of the algorithm in the case of large disturbances,noise uncertainty and so on.The result of simulation experiment shows that:1) The locating accuracy of the combined filtering algorithm is higher than that of the unscented Kalman filtering algorithm and the adaptive iterative unscented Kalman filtering algorithm in the case of large disturbance;and 2) In the case of non-Gaussian noise distribution,the unscented Kalman filtering algorithm and the adaptive iterative unscented Kalman filtering algorithm show a divergent trend,while the combined filtering algorithm can still converge stably.

Three-dimensional trajectory is a complex time series with continuity and interaction.Aiming at the problem of UAV flight trajectory prediction and by using the deep learning theory,a method for UAV flight trajectory prediction based on bidirectional Gated Recurrent Unit (GRU) is proposed,which can further improve the utilization rate of trajectory information.Firstly,the UAV flight dynamics model is established,and the flight trajectory samples in different states are obtained by simulation.Secondly,the Mean Square Error (MSE) is used as the loss function to determine the parameters of hidden nodes and iterations of the bidirectional GRU model.Finally,the Adamax algorithm is used to optimize the bidirectional GRU model for realizing the prediction of the UAV flight trajectory.Experimental results show that:1) The Mean Absolute Errors(MAE)of the prediction results of the bidirectional GRU model in the X,Y,and Z axis directions are all within 5.0 m,and the average time for trajectory prediction is 4.2 ms approximately;and 2) Compared with RNN and GRU models,our method has better prediction effect.Thus it will have fine application value.

PID controllers are relatively common in quad-rotor flight control systems,and one of its essential problems is the tuning and implementation of parameters.Common parameter tuning methods include fuzzy control,neural network and manual parameter tuning.Aiming at the difficulty of PID controller parameter tuning for quad-rotor aircraft,this paper proposes a PID parameter tuning method based on chaotic Particle Swarm Optimization (PSO).First,the fast convergence speed of PSO,and the ergodic and random properties of chaotic sequence as well as its sensitivity to initial values are used to adjust PID parameters more quickly and accurately.In addition,combined with the adaptive inertia weight method,the global search ability and local search ability of the PSO are balanced.In each iteration process,the particles can choose the appropriate inertia weight in each dimension of the search space according to their own situation.The results of simulation experiments show that the chaotic PSO proposed here can quickly and accurately solve the required parameters, which verifies the effectiveness of the algorithm.

In order to improve the terminal penetration capability of missiles and ensure the accuracy of maneuvering target attacking,a novel guidance law for missile penetration is proposed.Firstly,an adaptive disturbance observer is developed to estimate the acceleration of target maneuvering.The designed observer can estimate the target maneuvering in finite time without knowing the upper bound of target acceleration in advance.Secondly,a sliding-mode surface is constructed by using the guidance error and the normal maneuvering velocity,and the guidance accuracy is not affected by the additional maneuvering through the maneuvering-attenuation design.Thirdly,based on the estimated target acceleration and the design of continuous penetration maneuvering,the finite-time-convergent guidance law is constructed.The designed guidance law is continuous and can ensure the finite-time convergence of guidance error.Finally,simulation is made considering the offence-defense confrontation between the maneuvering target,the interceptor and the penetration missiles,and the results show that the designed guidance law has high precision and strong penetration capability.

Considering that the agents cannot communicate normally with each other under Denial-of-Service (DoS) attack,the problem of containment control for discrete,heterogeneous multi-agent systems based on graphical diagram is studied.A distributed state observer is constructed with consideration that the follower state can not be obtained online.History information is added in the design of each followers controller,and a distributed dynamic state feedback control scheme is adopted to strengthen the constraint conditions of containment control through internal and external systems.Therefore,the followers in the system can track the leader in time,and the problem of system output regulation is solved.By using piecewise Lyapunov function,linear matrix inequality and other techniques,sufficient conditions for the asymptotic convergence of the system are obtained.Finally,numerical simulations verify the validity of the proposed theoretical results.

The autonomous obstacle avoidance capability in complex dynamic environment has become a key problem for UAVs.Aiming at the shortcomings of the existing obstacle avoidance algorithms,a hybrid obstacle avoidance strategy is proposed based on the velocity obstacle method,which can adjust the direction and speed at the same time.Firstly,according to principle of the velocity obstacle method,it is judged whether there is flight conflict between the UAV and the dynamic obstacle.Then,in the cases of single dynamic obstacle and multiple dynamic obstacles,the relationship between the course and speed that need to be adjusted for UAV obstacle avoidance is accurately deduced by mathematical formula.Under the constraint of objective function,the optimal obstacle avoidance strategy is solved.The simulation results show that the proposed algorithm is effective and efficient under single and multiple dynamic obstacles.

Aiming at the problem of blind PN code estimation of long period code Direct Sequence Spread Spectrum (DSSS) signals,a spread spectrum code estimation method based on improved Genetic Algorithm (GA) is proposed.Firstly,the GA is improved by initializing the population with observation signals,retaining the optimal individuals and adding some randomly generated individuals to prevent local optimization.Then,the synchronization point of PN code and information code is estimated according to the spectral norm of signal covariance matrix.Finally,a period of observation signal is intercepted,and the improved GA is used to estimate the PN code.The simulation results show that the improved algorithm speeds up the convergence process,reduces the number of iterations,and achieves good results under the condition of low SNR.

A Stepwise Iterative Convex optimization (SI-CVX) algorithm is proposed for directional modulation signal synthesis of time modulated sparse antenna array.By analyzing the switch-on duration time and the switch-on moment of the array element,the upper and non-convex lower bounds of the pattern are converted to convex problems.By optimizing the main band pattern and sideband pattern step by step,only the main band is remained in the desired radiation direction,and the sideband signal is null.The efficiency and stability of the stepwise iterative convex optimization algorithm is verified by the simulation of time modulated sparse linear array and the purpose of directional modulation signal synthesis is achieved.

In order to improve the accuracy of semantic segmentation in outdoor scenes,an improved DeepLabV3+ neural network segmentation algorithm is proposed.The backbone part adopts a grouped ResNest network,thus the training weights of various types of targets account for different percentages.Then,the Atrous Spatial Pyramid Pooling (ASPP) module is improved by using densely connected mode to expand the perceptual field without sacrificing feature spatial resolution and to improve feature reuse efficiency.The decoding side fuses the low-level semantic features extracted from the encoding side at three different scales to recover the spatial information lost in the downsampling process.The experimental results show that the algorithm not only improves the segmentation accuracy of the target in the detection of CityScape dataset,but also has a significant improvement in both full-scene understanding and detail processing ability.

Dense False-target Jamming (DFJ) is generated by intercepting full-pulse radar signal,which can effectively suppress radar system by continuously copying and forwarding.Jamming characteristics of DFJ is analyzed,and an echo processing tool is designed,namely,Two-Dimensional Reduced Fractional Fourier Transform (2D-RFRFT).On this basis,an adaptive jamming suppression algorithm based on 2D-RFRFT is proposed for the self-defense DFJ in Linear Frequency Modulation (LFM) coherent radar.According to 2D-RFRFT difference between the actual target echo and the jamming signal,Median Absolute Deviation (MAD),a robust statistics,is introduced to identify and eliminate jamming outliers.Through further order adjustment,the objective of suppressing the jamming while detecting the maneuvering target is realized.Simulation results have verified the feasibility and effectiveness of the proposed echo processing tool and jamming suppression algorithm.

Aircraft systems transmit information over wired networks require a large number of cables,which will increase the weight of aircraft,the complexity of wiring design,and the cost of aircraft maintenance.Wireless networks have reduced weight and system wiring because they do not need laying cables,which will directly improve the aircrafts survivability and system reliability,and the tolerance to water,hydraulic oil,smoke,fire and other environmental factors.This paper summarizes the current research situation of wireless network technology,analyzes the application scenarios and technical challenges in the aircraft system,predicts the future development trend,and gives the suitable wireless network technologies for each application scenario by using the judgment standard combining technical index with profit index.

The concepts and research situations of the air-to-air missiles proposed by the United States are studied,such as Dual Range Missile (DRM),Joint Dual Role Air Dominance Missile (JDRADM),three types of target terminator (T3),Small Advanced Capability Missile (SACM),Long Range Engagement Weapon (LREW),and AIM-260 (JATM) etc.,and an analysis is made to their development trends and characteristics.Based on which,the understanding of the future air combat of America is summarized,and the air combat capability possibly constructed by its air-to-air missile development is presented.Some suggestions are given for Chinas future air-to-air missile development,such as accelerating the development of the next-generation air-to-air missile and the study on tactical warfare,building the capabilities of system penetration and intelligent game,and improving the flexibility of operational application.

Traditional single server distributed storage system is difficult to meet the real-time requirements of the avionic system.The cloud storage technology can effectively improve the speed of data access.In order to improve the real-time performance of data access,a cloud storage scheme suitable for avionic system is designed.The data is distributed and stored in multiple servers,and the task is decomposed into multiple subtasks according to the characteristics of data storage.The subtasks can access multiple servers simultaneously, so as to improve the real-time performance of data access.The experimental results show that the cloud storage system with multi-machine cooperation has higher access speed than the traditional single machine storage system does.

Aiming at 3D imaging algorithms for irregular high-rise buildings in urban areas,a GEO SAR reconstruction algorithm for complex and irregular buildings is optimized based on the Attributed Scattering Center (ASC) model.The Beidou satellite is used as a radiation source,the airborne receiver used as the signal receiving platform,and the reflected GNSS signal as the echo signal.An optimization model of convex optimized parameters is established, and an iterative method based on variable division and augmented Lagrangian technique is proposed.Echo simulation and imaging processing are implemented based on the GEO SAR system,and TeslaK20C simulation platform is used to complete the building imaging processing.The simulation results show that the generated images can reflect the characteristics of the building structure and the difference in scattering intensity,and have good accuracy,completeness and visibility.It proves that the constructed high-rise building target model can be applied to the simulation verification of the GEO SAR imaging system.

This paper focuses on the operational configuration calculating of passive smoke jamming equipment for fixed positions,and the improving of the operational decision-making capability of the commander and the applicational efficiency of the equipment.First,an analysis is made to the principle of passive smoke jamming calculation.Second,the procedure and steps for calculating the positions and quantity of the jamming equipment are expounded in detail.At last,the practicability of the calculation method is verified by an example analysis.It is proved that this method has certain theoretical and practical value for operational planning.

Aiming at the recoil problem of armed helicopters caused by launching rocket projectiles,this paper proposes a recoil compensation control method based on preset performance control to ensure the helicopter stability during rocket projectile launching.Initially,combined with a helicopter attitude model, the recoil force and its influence on the helicopter attitude dynamics when launching rocket projectiles are analyzed.Then,based on the preset performance theory,the preset performance function is considered to constrain the dynamic performance of the attitude tracking error,and the compensation controller is designed in combination with the Backstepping method.Finally,the effectiveness of the designed controller is verified by simulation.This ensures that the helicopters pitch angle is quickly stable within the firing interval when the rocket projectiles are launched continuously,which meets the actual combat requirements.

By using the method of three-dimensional coordinate transformation matrix,the specific rotating transformation relationship of the precision tracking image and the angular error with the azimuth and pitch axes in an Acquisition,Tracking and Pointing (ATP) system was studied,which supplies a correct reference for the processing of the precision tracking image and the angular error,and ensures the stability and high precision of the tracking.

In view of the nonlinearity of the dual-axis,dual-frame photoelectric platform motor and the influence of the coupling caused by the interaction between azimuth and pitch shafting on the control accuracy,an inverse system based nonlinear decoupling control method is proposed for photoelectric stabilized platform.Firstly,according to the dynamic models of azimuth and pitch frames of the dual-axis photoelectric stabilized platform,the state space equation is established,and then an inverse system is designed to obtain the state variables of the system.The inverse system is connected in series with the original system to obtain a pseudo linear system,which transforms the original single coupled nonlinear multi-input multi-output system into two linear decoupled single-input single-output subsystems,so as to eliminate the strong nonlinear coupling between the azimuth and pitch shafting.Finally,the system simulation platform is established in Matlab.The simulation results show that the nonlinear decoupling method of photoelectric platform based on inverse system can effectively reduce the coupling between azimuth and pitch axis system,and improve the stability accuracy of the platform system.

With the increasing complexity of airborne display system,graphics processor (GPU) is used more and more widely to generate display images. However,due to the high complexity of GPU,it also brings challenges to airworthiness certification.First,analysis is made to the usage scenarios of GUP in airborne display and the risks it brings,and the current airworthiness requirements are studied.Then,the solutions to the problems concerned in the airworthiness application of GPU are given from the two technical routes of using FPGA and using COTS devices,and the two technical routes are summarized. The research results are helpful for solving the airworthiness problem of the application of GPU in civil aircraft display,which supplies a reference for existing display equipment manufacturers on the design of graphics processing hardware.

Based on research and analysis of the application technical characteristics of ARINC661,this paper proposes an interface component design method based on functional interfaces in consideration of the development activities carried out under the User Application of Cockpit Display System (UA-CDS) business architecture.This method is guided by the core business functions of UA,and a display control component library that meets the requirements of UA functions is established,which supports the componentized application development model of CDS.Therefore,the design and development activities of UA and CDS are standardized,which improves the efficiency of interface system development.

According to the characteristics of complex illumination changes in different environments during positioning and tracking,an ORB feature point extraction method with adaptive threshold is proposed. Firstly, the threshold is extracted adaptively by calculating the feature points around the image block automatically,which is then used for extracting the image feature points. Then,the horizontal binocular model is used for feature point tracking.Datasets are used for tests under different environment for comparison of different methods. The experimental results show that the improved method in this paper has larger detection range,higher extraction speed,higher stability in feature point extraction,and has better RMSE performance in trajectory tracking comparison.