This paper introduces a novel path planning algorithm for Unmanned Aerial Vehicle (UAV) based on theory of fluid avoiding obstacles.To the problem of path planning which aims at the global optimum,not only the influence of terrain constraints on path safety but also the performance constraints of UAV should be taken into consideration,thus a feasible and smooth path will be planned in the three-dimensional space.The computation complexity and the path quality by traditional algorithms are usually unsatisfactory,hence we propose the method inspired by the phenomenon that water can avoid rocks and reach the destination.The common features between this phenomenon and the path planning problem are extracted and analyzed,and then the mathematical model generalizing the phenomenon is constructed on the basis of theory of fluid mechanics.By selecting the optimal streamline from the fluid field under the evaluation index,the three-dimensional optimal path under flight and environment constraints is obtained eventually.

Pulse Doppler fuze has the ability of distance and velocity measurement,which make it have strong anti-jamming capability.In order to improve the jamming effect to the pulse Doppler fuze,a multiple velocity false targets jamming method based on Doppler modulation was designed based on analysis to its working principle.The working principle of multiple velocity targets generating was proposed,then the output of pulse Doppler fuze under the jamming of multiple velocity false targets was derived.Simulations were made to analyze the jamming effect of multiple velocity false targets.Theoretical analysis and simulation results demonstrate that this jamming signal can produce multiple false targets with different velocities and the jamming parameters can be altered flexibly according to the requirement.It is proved that this method can jam the pulse Doppler fuze efficiently.

Due to its strong penetrability and all-day,all-weather operational capability,the passive millimeter-wave imaging technology has a broad application prospect in remote sensing and guidance.In target recognition,it needs to extract features of the initial millimeter radiometric image.According to the actual imaging characteristic of millimeter-wave,an algorithm of image feature extraction based on genetic algorithm is proposed.In this algorithm,Otsu′s method and genetic algorithm are combined to obtain the optimal segmentation threshold, and then morphology processing is implemented to the segmented image for extracting the target features.Experimental result indicates that the proposed algorithm can effectively extract the features of millimeter-wave radiometric image.

The Digital Signal Processor (DSP) is specially designed for signal processing.In recent years,the DSP has found wide application in signal processing,image processing,communication,traffic and aerospace etc.As a practical part of image processing,the image haze removal has been researched for decades.During the research and development of haze removal algorithm,the Matlab and C programming language were usually used,and were supported by DSP.Yet,the efficiency was too low by simply running the source code.To solve this problem,a novel algorithm is proposed for optimizing the algorithm and improving the processing effect.The multi-core DSP and development tool of TI Company are used for real-time optimization of C code and parallel processing.A fine optimization effect is obtained,which shows that the method can be used for processing hazy images with low resolution ratio in realtime.

A distributed control method for formation of quadrotor UAVs is presented with introductions on the fundamental knowledge of graph theory and consensus of swarm system.The quadrotor UAV is described as a second-order integrator dynamic system,and the relative position is used to describe the UAV formation shape.The quadrotor UAV formation is modeled based on the communication topology relationship of quadrotors.The strategy of follower-leader method integrated with graph-based method is explored.A second-order consensus algorithm is presented,with which the fleet can complete formation gathering and formation maneuvering.Finally,the effectiveness of this algorithm is shown through the simulation results.

A stable fuzzy H∞ adaptive controller was proposed to deal with the output tracking problem of a hypersonic vehicle subject to parameters uncertainty.Considering the parameter uncertainty in the system,we used a fuzzy adaptive system for online approximating the nonlinear item in dynamic inversion controller, which was subject to parameter uncertainty.In the meantime,robust compensation was introduced,which could reduce the impact caused by approximation error of the fuzzy logic system and the external disturbances,and could improve the H∞ performance of the system.The stability of the whole system was proved by using Lyapunov theory.The simulation results demonstrated that: by using the method,the hypersonic vehicle may have fine tracking performance and high robustness.

The existing sparse reconstruction algorithms for DOA estimation cannot suppress noise and are not applicable under colored Gaussian noise,and the maximum number of sources that could be handled by these algorithms is smaller than the number of array elements.In order to solve these problems,a sparse representation model is constructed based on the fourth-order cumulant of received data,which suppresses the noise and realizes array extension by producing virtual array elements.And then,singular value decomposition is used upon the cumulant matrix to simplify the model.The simplified model not only reduces the scale of data,but also further suppresses noise.When the sparse representation model is solved by using weighted l1 norm algorithm,it′s unnecessary to select the regularization parameter which balances reconstruction residual with the sparsity of solution.Theoretical analysis and experimental results show that the proposed algorithm is applicable under both the white or colored Gaussian noise,and the maximum number of sources that can be handled is larger than the number of array elements,with higher angle resolution.

The problem of aviation pre-disposition under multiple constraints was studied.Through analyzing requirements of aviation operation,two kinds of force pre-disposition optimization problems,maximized operational efficiency and minimized quantity of operational force,were presented.According to influencing factors of aviation pre-disposition,integer programming models were built up for the two kinds of aviation force pre-disposition,in which multiple constraints were taken into consideration,such as force quantity,task requirement,airfield capacity and supportability.The solution by traverse algorithm was designed to those two models,and the key calculating codes were given,then all the optimum solutions satisfying the objective function could be obtained.Finally,simulation was made to the two kinds of models and the algorithms.The results show that the optimum aviation pre-disposition scheme can be obtained by using the integer programming models and the solution methods.

The problem of aviation pre-disposition under multiple constraints was studied. Through analyzing requirements of aviation operation, two kinds of force pre-disposition optimization problems, maximized operational efficiency and minimized quantity of operational force, were presented. According to influencing factors of aviation pre-disposition, integer programming models were built up for the two kinds of aviation force pre-disposition, in which multiple constraints were taken into consideration, such as force quantity, task requirement, airfield capacity and supportability. The solution by traverse algorithm was designed to those two models, and the key calculating codes were given, then all the optimum solutions satisfying the objective function could be obtained. Finally, simulation was made to the two kinds of models and the algorithms. The results show that the optimum aviation pre-disposition scheme can be obtained by using the integer programming models and the solution methods.

Considering the estimation degradation caused by the pure rotational movement in the monocular vision system and the motion parameter constraints,we proposed an OPA-based spatial-time constraint pose estimation algorithm for monocular vision systems.The OPA algorithm was used to detect and correct the estimation degradation before estimating the essential matrix and translational direction vector.Combined with the time-related constraints of camera in motion process and the space-related constraints of image feature point,the estimation to navigation parameters of the monocular vision system were obtained.Comparative analysis of two sets of experimental results shows that the proposed algorithm has higher accuracy and stability compared with the conventional estimation algorithm.

Target threat assessment is very important for air combat mission planning.Due to the uncertainty and fuzziness of target information in traditional assessment model,the model and algorithm for target threat assessment based on improved Generalized Regression Neural Network (GRNN) are proposed,with multi-aircraft air-combat formation as the starting point.This optimization algorithm can quickly find the optimal scatter coefficient through traversing values within the scatter coefficient interval,thus enabling the model to reach the optimal simulation output.Considering that most of the current air-combats are formation operation,the overall threat level of targets to our formation is selected as the assessment criteria,which improves the reliability of assessment results.Finally,an example is given to verify the effectiveness and correctness of this optimization model.

Variable pitch quadrotor aircraft can control the tension of each corresponding rotor by changing the pitch of four rotors,thus adjusting the quadrotor aircraft′s posture and position.Compared with the traditional single speed regulation,quadrotor aircraft′s pitch control strategy is of great significance for improving its own maneuverability and reliability,which has a broad application prospect in micro aircraft′s formation flight and precise mission in the future.To analyze the realizability to control the variable pitch quadrotor aircraft′s wide-angle nonlinear motion,a non-linear dynamic model of aircraft is established with Eulerian approach,and a non-linear control method with feedback linearization is applied to the established aircraft model.Finally,by simulating the quadrotor aircraft′s motion process under non-linear control with Simulink software,the effect of nonlinear control theory on quadrotor aircraft′s motion control is discussed,which provides a reference for realizing control of variable pitch quadrotor aircraft′s wide-angle nonlinear motion.

Modeling and hovering control of a tilt-rotor UAV with tri-rotor configuration were studied.A 6-DOF nonlinear dynamic model of this tri-tilt-rotor UAV was established with Newton-Euler method,which was then simplified.On such basis,altitude and attitude controllers in hovering mode were designed respectively.The altitude controller was designed with PID control based on feedback linearization,and the attitude controller was composed of Backstepping-based PID controllers.Finally,the designed controllers were used for simulation experiment,and the experimental results show that the designed controllers can meet the system′s requirements for performance control.

Integrated Modular Avionics (IMA) system adopts a resource sharing architecture,which provides a more sophisticated and powerful avionics functionality,but also brings a more complex fault proliferation model at the same time.To solve this problem,we proposed a reliability assessment method based on Architecture Analysis and Design Language (AADL) and Generalized Stochastic Petri Nets (GSPN).Firstly,the system′s architecture and fault information were described with AADL language,and its AADL reliability model was established.To further analyze the dynamic behavior of its faults,the rule for transformation from AADL reliability model to GSPN model was studied,and IMA system reliability was assessed by analyzing the GSPN model.Finally,the effectiveness of this method was validated by reliability assessment of the display function of IMA system,and suggestions for selecting the architecture of display function were given via experimental comparison.

The article introduces three types of laser-guided weapon guidance systems: semi-active laser guidance,laser beam riding guidance and laser active imaging guidance.Analysis is made to the working principle of the three kinds of laser guidance systems and the performance of the laser-guided weapons.Based on which,the advantages and disadvantages of the three kinds of laser guidance systems are presented, with focus on the laser active imaging guidance and its development.The tendency of laser-guided weapons in the future is pointed out in the end.

Generally,the aviation communication system has some constraints,such as power,bandwidth and latency.To satisfy its requirements of high coding gain and low latency to channel coding,the paper derives the theoretical Shannon limit on the minimum SNR required for coded system,especially for the binary communication system.And then,the performance of several typical kinds of channel coding is analyzed through simulation.Finally,qualitative analysis is made to the application scope of the different channel coding methods with consideration of the technical indicators of them.The conclusion has engineering significance for the selection of channel coding in aviation communication systems.

This paper focuses on the foreign theoretical models of trendline life assessment methods.Based on the basic concepts of tolerance intervals,tolerance limits,tolerance interval and limit of normal population, the established theoretical model is derived.On this basis,the regression model is improved in order to increase the prediction accuracy.Considering the actual situation,the improved regression model is discussed,the rationality of using a linear regression model as a trendline life assessment method is proved.Finally,taking a certain primer as an example for calculation,the result shows that the storage life of the primer is approximately 22 years.

The ground dispersion of aerial terminal sensitive submunition was studied.The characteristics of terminal sensitive submunition were analyzed based on the comparison with the gun shot terminal sensitive submunition.Then,a method was proposed for quick estimation of the bullet dispersion based on the upper and lower bounds of bullet drop-points.How the different scattering conditions influence the bullet dispersion was also studied,and data was collected for simulation.The result shows that,the limiting error of the estimation method is within the allowable combat range,and the scattering velocity and trajectory angle have an important influence on the bullet dispersion′s radius.

S-curve global dimming algorithm can reduce the power consumption of LED-lit Liquid Crystal Display (LCD) and improve the static contrast of display images.In order to further increase the power-saving efficiency,a two-step dynamic dimming algorithm based on S-curve is proposed.First,the gray levels of all sub-pixels of the input image are adjusted according to the maximum gray level,the pixel gray levels of input image are upgraded on the whole.Then,the pixel compensation is performed to the linearly amplified image with S-curve,and backlight brightness signals after adjustment are output at the same time.The simulation results of 40 typical images show that: the average backlight power is saved by 30%,and the static contrast is increased by 33%.The engineering prototype is developed to test six common TV programs.The result shows that the overall average power-saving is 25.1%,and the static contrast is increased by 30%.Compared with S-curve global dimming algorithm,the proposed algorithm can further increase the power-saving efficiency by 10% while maintaining the same display performance.

High-repetition-rate range-gated underwater lidar imaging is achieved by multi-pulse accumulation.Noise characteristic analysis of the high-repetition-rate range-gated underwater lidar image is a necessary step for further improving the imaging quality by image post-processing.Through an analysis of the characteristics of both additive noise and multiplicative noise,noise characteristics of the single pulse range-gated underwater lidar image,high-repetition-rate range-gated underwater lidar image and multi-frame averaged high-repetition-rate range-gated underwater lidar image are analyzed.The experimental results show that: 1) The single pulse range-gated underwater lidar image is mainly affected by the multiplicative noise; 2) The high-repetition-rate range-gated underwater lidar image is affected by both the additive noise and multiplicative noise; and 3) After multi-frame averaged,the high-repetition-rate range-gated underwater lidar image mainly contains multiplicative noises.

A scheme for design of adaptive neural network controller is proposed for the class of non-affine systems with dead-zone nonlinear input and unmodeled dynamics.Compared with the existing methods,this scheme can improve the processing effect for unmodeled dynamics,simplify the design procedure and increase the tracking precision.Furthermore,it can make the stability analysis more reasonable.By theoretical analysis,the closed-loop systems is shown to be semi-globally uniformly ultimately bounded.Simulation results demonstrate the effectiveness of the proposed method.

To verify the performance of the photo-electronic device and the effectiveness of the image processing algorithm in different occasion,an image processing simulation and evaluation system was designed.It is controlled by the host computer and FPGA+DSP+DSP is used as the core processor.The system can check and evaluate the performance of different processing algorithms by collecting video images in real time,or using the video images stored in the computer previously.Different image detection algorithms are integrated in the system,which can be used for extracting the feature of the images.Playback can be used in the system and the processing results in each step are visible.Experiments show that the system can satisfy the requirement to real-time performance.The system has been successfully applied to the engineering practice.

Using digital zenith instrument for positioning the observation station is an astronomical positioning method with high accuracy.In calculating the position of observation station,there lacks an effective method for screening the star data.Direct processing of the star data obtained from experiment always has an influence on the final positioning accuracy.In order to solve the above problems,a method for star screening is proposed.With residual error as the object of study,it uses Grubbs criterion for repeating screening of star data in iterative computation,and then uses the least square algorithm for calculation.The processed result of experimental data has rejected the stars with gross error and improved the reliability of calculated data,which can improve the positioning accuracy by about 5 m.

To the synchronization problem of the chaotic systems with uncertainties and not all the state variables are measured,a nonlinear observer is designed based on Linear Matrix Inequality (LMI) method.Assuming that the nonlinear variable satisfies a certain condition,the designed controller will synchronize with the drive system.The existence of the controller is given in terms of a LMI,and the design of the controller is obtained by solving the LMI.Moreover,a secure communication scheme is given by using the observer designed.Finally,analysis of the synchronization system and numerical simulation are presented to show that the method proposed is effective.