A formation control method of quadrotor UAVs based on high-order consensus is designed.Firstly, by using feedback linearization,the nonlinear mathematical model of quadrotor UAVs is simplified into two four-order linear subsystems and two two-order linear subsystems.Then,the fundamental knowledge of algebraic graph theory and matrix analysis are introduced and the position deviation matrix is used to describe the UAV formation shape.Under the above conditions,a high-order consensus formation control algorithm under fixed topology is designed,and the sufficient conditions for its gradual consistency are given.Finally,the Matlab simulation experiment shows that the quadrotor UAVs can complete the behavior of formation gathering and formation shape changes.

Nowadays, the methods of determining the index weights of aerial target threat assessment for warship formation are unreasonable. On the basis of designating the improved target threat assessment indicators, the combined index weights of threat assessment is determined by using IAHP and the entropy method respectively, so as to get the index weights of threat assessment. Considering the characteristics of warship formation, the aerial target threat assessment models of the warship and the warship formation are proposed based on the improved TOPSIS method. The model is suitable for warship formation to make aerial target threat assessment under cooperative combat environment. Finally, a simulation example is given to demonstrate the effectiveness of the model.

In order to solve the problem of poor robustness of Simultaneous Localization and Mapping (SLAM) to noise interference and motion trajectory prediction error in complex environment,the adaptive estimation theory and robust H∞ control criterion are introduced into UKF,and a robust adaptive UKF-SLAM algorithm is proposed.The algorithm uses adaptive estimation theory to construct the robust factor and the adaptive factor,adaptively estimates the equivalent covariance matrix of measurement and state noise,and realizes coarse error separation and adaptive compensation of noise variance.The robust H∞ control criterion is used to iteratively update the system state mean and covariance to improve the robustness to noise interference and reduce the prediction error.Simulation results show that the algorithm can ensure that the mobile robot has good robustness and positioning accuracy in different noise environment.

To solve the problem of communication topology switching for UAV formation,a method for UAV formation control based on the joint errors is proposed.This method is essentially an extension of the consensus control theory.Based on the position of the UAV,an elastic look-ahead point is set.Using the position and velocity errors of each UAV,the linear state equation with the joint errors is established.The error feedback between other UAVs in the formation is introduced and an elasticity extension consensus controller is designed.The classic consistency controller is a special case for the extended consensus control in the case of not knowing certain errors between the UAVs.Finally,the stability of the fixed communication topology system is verified by using the Hurwitz stability analysis method,and the sufficient conditions for its stability are given.The condition of exponential convergence of switching communication topology is obtained by using Lyapunov stability analysis method.The simulation results show that the method can keep the formation stable under fixed and switched topologies and the elasticity formation can adapt to the speed change of the leader UAV.

The Bayesian estimation of the parameters and reliability function for Wiener process are obtained based on the generalized entropy loss function by using both non-informative and conjugate prior distribution,and it is compared with the Bayesian estimation under the square loss function and maximum likelihood estimation. The simulation results show that: The Bayesian estimation under the generalized entropy loss function has the smallest mean square error and the highest precision, and the expression of the estimation is flexible, which can effectively describe the situation where the risks are different due to over-estimation and under-estimation.

Aiming at improving the damage-mitigation effect and guaranteeing the flight performance,a damage-mitigating controller based on the modified prescribed performance algorithm is designed for the wings of the Hypersonic Flight Vehicle (HFV) during hypersonic flight.Firstly,the stress condition of the critical component of the wing is analyzed,and the damage model is constructed to describe the real-time damage evolution.Secondly,based on the prescribed performance algorithm,the exponent term and the error transformation function are modified to satisfy the demand of the HFVs dynamics.Finally,a corresponding attitude damage-mitigating controller is designed by using the HFV model.The simulation results prove the validity of the designed controller.

Considering the autonomous landing process of the unmanned helicopter,a landing scheme of the unmanned helicopter based on visual guidance is designed independently.The landing landmark is designed according to the actual application situation.The landing landmark features are obtained by the method of combining Canny edge detection with Harris corner detection,and the precise target location and heading information are obtained by coordinate transformation.Based on the Extended Kalman Filter(EKF),the visual processing information and INS information are fused and processed,and then a flight test is carried out.The results show that the system meets the verification requirements of helicopter autonomous landing.

To solve the problem that the traditional Loop Closure Detection(LCD)algorithms are unstable and easy to fail in dynamic scenes,an algorithm that can accurately detect the loop closure under dynamic scenes is proposed.First,the algorithm for distinguishing the dynamic from the static features based on the scenes flow is improved so that the dynamic and static points are more accurately determined.Then,the dynamic feature points are removed and clustering processing is performed.The TF-IDF entropy of each node of the image in the visual dictionary tree is used as the weight of the image in the visual word,and a score vector is constructed to describe the scenes.Finally,the negative exponent power function is used as the similarity score function to calculate the similarity scores of the two images.The similarity score between the current frame and the candidate key frame is calculated,and after the final loop closure confirmation,the final key frame forming a loop closure with the current frame is obtained.The experiment of the actual lab scenes shows that the proposed algorithm can effectively detect the loop closure in the dynamic scenes.

In order to solve the problem of parameter setting of the extended state observer used in nonlinear dynamic system,a parameter setting model based on BP neural network is established.The online gradient descent method is used to train the network so as to ensure the learning ability of the dynamic system.The incremental Delta-Bar-Delta algorithm is introduced,and the information of input data and learning experience are used to realize the adaptive adjustment of the learning rate and improve the adaptability of the online gradient descent method.It can be seen from the numerical simulation that the parameter setting model possesses the advantages of good dynamic performance and high accuracy compared with the traditional parameter setting model,and it can improve the dynamic setting accuracy of the parameters of the extended state observer of the nonlinear system,so that the controlling performance of the ADRC system is improved to a certain extent.

Accuracy and real-time performance are two important indexes of target detection.In order to ensure that the target is quickly and accurately detected in a variety of complex scenarios,an accurate target tracking algorithm is proposed using Hypercomplex Fourier Transform (HFT) saliency calculation,Efficient Sub-window Search (ESS) and OTSU algorithm.First,the input image is preprocessed by the HFT algorithm to obtain the saliency map.Then the target is searched globally and preliminarily located by using the efficient sub-window based on the saliency map.Then the image within the scope of the sub-window is segmented by using OTSU algorithm.Finally,the position of the sub-window is optimized according to the pixel value on the edge of the sub-window,so as to ensure accurate target detection.The experimental results show that the algorithm greatly improves the real-time performance of detection without significant increase of computing time.

Array antennas consisting of a large number of array elements are widely used in modern radar equipment.In actual application,the array antennas are constantly experiencing failed elements.The failure probability of array elements of different numbers in array antennas of different sizes is analyzed,and the performance analysis process of array antennas under different combination modes of failure elements is designed.Taking the Chebyshev linear array and the Taylor linear array of different scales as examples,the relationship of maximum sidelobe level,average sidelobe level,half-power beamwidth,first nulls beamwidth,directivity coefficient of the array antenna with the failed elements amplitude and position is analyzed.The analysis results provide a basis for self-repairing of array antennas with failed array elements.

Aiming at the issue of shipboard helicopter in antisubmarine operational application,this paper summarizes the domestic research status of antisubmarine operational applications of shipboard helicopters,including submarine searching,tracking and attacking,from the aspect of antisubmarine tactics.The shortcomings of current researches on antisubmarine operational application are analyzed,and key items of research in the future are also given.

In the past 70 years,foreign aviation sonobuoys have experienced different stages of development and technical routes.This paper briefly introduces and summarizes the development history of aviation sonobuoys in the United States,Britain,Russia and other countries,summarizes their development rules and experience,and predicts the direction of sonobuoy development by analyzing the characteristics of future underwater combat and foreign modern research examples.

This paper focuses on the domestic probe-drogue aerial refueling,and designs a set of vision-based autonomous aerial refueling system for drogue tracking and locating.Firstly,the tanker system is modeled.The finite element analysis is used to model the refueling hose drogue,which provides reference data for the movement of the drogue.A two-dimensional image localization of the drogue is completed by using the minimum ellipse localization,and the LHM algorithm is used to complete the three-dimensional localization.Then,considering the poor stability and low output frequency,EKF is introduced to improve the robustness of the system and decrease the time for image processing.Finally,the simulation results show that the vision-based measurement using EKF can improve robustness and output frequency under different turbulence conditions.

There are numerous spare parts in the carrier-borne aircraft landing guidance equipment system,and the effect of traditional unit-level spare part support is limited,so it is impossible to evaluate the entire spare part system efficiently and comprehensively.In regard to these problems,the k/N(G) voting relationship is introduced to decompose the complex system into a series-parallel structure equivalently.The prediction model of the spare part support probability,use availability,the utilization rate and other key indicators under different life distribution types of the spare part is proposed.In regard to the deficiency that the indicator statistics can only be obtained after finishing the task,the analytical calculation method is used to pre-assess of the spare part plan to improve the effect of spare part support,and the calculation method of each index on the system level is further given.Through an example analysis,it is proved that the accuracy and comprehensive evaluation ability of the spare part support plan on the system level are improved compared with that of the traditional method,and the simulation results are in line with the actual situation.

A target tracking method is proposed based on local feature index structure,which introduces Bag of Visual Word(BoVW) into the tracking method.A target tracking method that does not rely on a specific feature type is constructed,which solves the calculation and measurement problems when using the feature descriptor to perform similarity measurement in actual applications.Then,the accuracy and robustness of tracking are improved by eliminating the mismatched features and the correlation prediction of unmatched features.Finally, the foreground features of the target area are separated and the target area is optimally updated to obtain more accurate tracking results.

Improving shielding effectiveness of the shield cavity can enhance the protection capability of High Intensity Radiated Field (HIRF) of the airborne electronic system in civil aviation.Based on Robinsons model,a modified model is proposed to calculate the shielding effectiveness of a metallic shield cavity with non-central aperture array.The airborne communication equipment in civil aviation is taken as the research object.The modified model is utilized to compute the shielding effectiveness of the airborne communication equipment in civil aviation,and the correctness of the model is verified by comparing with the results of the 3D electromagnetic simulation software.Moreover,the impact of different aperture arrays,frequencies and positions on the internal electric field distribution of the equipment is analyzed by software simulation.The simulation result can serve as a reference for the design of a shield cavity and the layout of internal sensitive devices for airborne electronic equipment in civil aviation.

To meet the dynamic and steady performance requirements of the satellite attitude control system on the rotor speed of the Single-Gimbal Control Moment Gyro (SGCMG),a dual-mode control method based on genetic algorithm for quasi-dual-loop and phase-locked loop is presented,and the disturbance torque compensation control is introduced to realize the steady speed control of the rotor under interference.To simulate the current loop and speed loop control,the genetic algorithm is used to optimize the two sets of Proportional-Integral (PI) parameters to form a quasi-double loop controller with variable parameters.The dual-mode control consisting of the quasi-double loop controller and the phase-locked loop can realize high-precision control with fast response speed and low overshoot.For the problem that the rotation of the SGCMG frame disturbs the rotor speed,the causes of the disturbance are analyzed.The relationship between the frame speed θ· and the disturbance torque Td is derived by using experimental data.On the basis of the dual-mode controller,the angular rate feedforward controller is designed to suppress the interference in the form of torque compensation,and the fluctuation of the speed can be suppressed to 15% of that under no-compensation conditions.The steady-state error of speed is less than 0.045% when the desired speed is 4000 r/min.

A new unitized simulation testing platform is designed according to the characteristics of three technical indicators for the airborne Infrared Search and Tracking (IRST) system,which are large field of view,high spatial resolution and high scanning speed.The problem that the traditional simulation system cannot simultaneously meet the requirements of the three technical indicators is effectively solved.The simulation testing platform has five working modes and consists of four subsystems:a simulation center,an actuator,an emulator,and a display and control terminal.The actuator uses the scene generation method based on time sequence to segment the simulation scene with large field of view and high resolution into several sequence-based planar array simulation scenes with small field of view and standard resolution.The video signal and time sequence information of the planar array simulation scenes are sent to the emulator simultaneously by using the fiber network.The emulator adopts different processing algorithms to process the simulation video signal according to the working mode.The performance test results show that the platform can simulate the comprehensive performance,working modes and interface modes of the real airborne IRST system.It has been applied to the joint test of the avionic mission software and the performance test of the avionic system.

To solve the problem that the vertical resolution is low when using 16-line LiDAR to realize negative obstacle detection,which leads to the difficulty of negative obstacle detection and recognition, a detection method of negative obstacle based on IMU-LiDAR is proposed.The method establishes a multi-frame LiDAR point cloud data fusion model,which can effectively use previous point cloud data and detection results to obtain more environmental information,and improve the detection accuracy of negative obstacles.The 16-line LiDAR and the self-developed IMU sensor are used to conduct the tests.The results demonstrate that the proposed method can achieve the multi-frame fusion of the LiDAR point cloud,and the detection ability of the LiDAR on negative obstacles can be further improved.A more advanced environment awareness is achieved with lower hardware costs,which shows that the method has practical application value for the study of driverless technology.

Based on the Activity-Based Methodology(ABM),an architecture design method is proposed to solve the problems of design irregularity and data inconsistency.The architecture framework and development ideas are introduced,and three classic architecture design methods are analyzed:Structural Analysis and Design Technique (SADT),Object-Oriented Design Method (OODM) and ABM.The advantages and disadvantages of various methods are given.According to ABM,the architecture design method based on core architecture data is proposed,and the development process of the method is illustrated in detail.The development method based on core architecture data is used to establish the architecture model from the operational viewpoint for the future cooperative anti-submarine warfare mission conducted by underwater unmanned vehicle.According to the established model,the method has good operability.