To solve the problem of small infrared target detection under complex backgrounds, an effective algorithm based on saliency analysis in frequency domain is proposed. The infrared target is usually more significant than backgrounds in spectral domain. Thus, we can obtain the saliency map of the infrared image through some operations in frequency domain. In this way, target signal is enhanced and background clutter is suppressed. Then, an adaptive threshold is adopted to segment the saliency map and extract the region of interest. At last, the saliency of windows in the region of interest is measured to predict the exact position of the small targets. Theoretical analysis was made to the effectiveness of the algorithm. And to validate our algorithm, we conducted experiments on some typical infrared images that contain small targets. Experimental evaluation results show that our method can implement infrared small target detection under low signal-to-noise ratio fairly well, and the method is simple, effective, and can satisfy the real-time requirement while guaranteeing the detection accuracy.

Fast and effective image denoising is critical for improving the accuracy of laser active imaging guidance.Focusing on the speckle noise in imaging,a denoising algorithm based on the combination of improved wavelet threshold denoising algorithm and integral image based non-local means filtering is proposed.Firstly,noise analysis of laser active imaging is performed.Secondly,speckle noise is converted from multiplicative noise to additive noise by logarithmic transform.Then,the image is decomposed into two layers by wavelet transform:the improved wavelet threshold denoising algorithm is used for the high-frequency part of the first layer,and non-local means filtering is used for the high-frequency part of the second layer.Finally,inverse transforms are carried out and the denoised intensity image is obtained.Theoretical analysis and experimental results show that the proposed algorithm has fine denoising performance and the details of image are well protected.Meanwhile,the proposed algorithm meets the requirements of laser active imaging guidance for real-time image denoising.

Considering the application limitations of the current grouping consistency protocol,we proposed a fuzzy C-mean clustering algorithm and a new kind of grouping-consistency algorithm based on the information interaction between the groups.Firstly,the UAV vector composed of multiple combat factors is established,and separating/grouping of UAV formation is implemented based on the fuzzy C-mean clustering algorithm.Then,to overcome the deficiency of existing grouping-consistency algorithms,a new kind of grouping-consistency protocol considering the information interaction between groups is presented,and the corresponding criterion is proved based on the theory of stability and matrix.The simulation result proved the correctness of the criterion and indicated that the proposed grouping method and consistency protocol can effectively implement separating/grouping of the UAV formation and guarantee the grouping consistency.

To reduce the negative impacts of strong coupling of attitude dynamics,a coordination controller is proposed for the attitude dynamics of a hypersonic flight vehicle.Based on the variable coupling degree matrices,the coupling entropies are deduced firstly.Two types of coordinated factors are designed by using coupling analysis method,in which the coupling entropies of the state variables are taken as the parameters of the coordinated factors.The attitude controller is designed by integrating the coordinated factors.The simulation results indicated that the designed coordination controller can effectively coordinate the coupling impacts,and achieve satisfactory attitude tracking performance.

The design and optimization of active phase of the missile are very important for improving the missile's firing range. Taking the two-stage missile as an example, the trajectory optimization model of missile active phase is established. Then, a hybrid algorithm based on simplex method and Genetic Algorithm (GA) is proposed according to parameter optimization theory. The algorithm not only has fine global convergence performance, but also has fast convergence speed and high precision. Finally, the effectiveness of the proposed method is demonstrated by experiments. Compared with the initial trajectory, the velocity at the end point of the active phase is increased effectively, and the range is increased by 32%. Hence it is proved that the proposed method is feasible and effective for missile trajectory optimization.

This paper addresses a novel method to solve the three-dimensional pursuit-evasion game of Unmanned Aerial Vehicles (UAVs).Since this method combines the variational method with the pseudo-spectral method,it belongs to a semi-direct method.Firstly,the differential equations and its constraint conditions for solving the optimal control law of one player are derived by means of the variational method.Therefore,the differential game problem is transformed into an optimal control problem.Secondly,the optimal control problem is further transformed into a nonlinear programming problem by pseudo-spectral method.Finally,the SNOPT solver is utilized to obtain the numerical solution and simulation is carried out.The simulation results show that both players have adopted the optimal control strategies,which verifies the correctness,validity and rapidity of the method.

The performance of tracking algorithm may be seriously degraded due to the sudden state change of target.To improve the performance for maneuvering target tracking,a weight-based multi-innovation amendment algorithm with maneuvering detection is put forward.Firstly,in order to judge the moment of maneuvering precisely,we proposed a maneuvering detection algorithm based on the double error ellipses, which can increase the sensitivity to maneuvering by setting bilateral threshold.Then to decrease the maneuvering deviation caused by delayed amendment,we built up a mapping relationship between the distance and the weight based on Euclidean distance between the predicted measurement and the actual measurement.From the mapping relationship,the weight of the pre-amendment information was obtained and the utilization ratio of implicit information was improved.Finally,the simulation results of three scenarios indicated that the proposed algorithm is effective.Compared with the standard Kalman filter and adaptive fading Kalman filter,the proposed method has a higher cost-benefit ratio for both highly and weakly maneuvering target tracking.

The deployment of heterogeneous sensor networks is more complex than that of the homogeneous sensor networks,for which the influence of the heterogeneity of nodes should be taken into full consideration.Particle swarm optimization algorithm is used for the deployment of heterogeneous sensor networks.By integrating the heterogeneity adaptability strategy and improving the fitness function,a new particle swarm optimization algorithm adaptive for heterogeneity is proposed.Simulation results show that:Compared with the basic particle swarm optimization algorithm,the proposed method can accelerate the convergence speed,improve the network coverage performance,and effectively avoid falling into the situation that the local optimum is inferior to the global optimum.

To intercept high-speed maneuvering targets,a three-dimensional guidance model is built taking the autopilot's dynamic characteristics into consideration. To solve the problems of the strong nonlinearity and uncertainty of the guidance model,a three-dimensional nonlinear guidance law was designed with consideration of the dynamic property of the missiles and the maneuvering of the target. Then,an extended observer was used to estimate the maneuvering acceleration of the target. The result of simulation showed that the extended observer had better performance than the sliding mode differentiator under the interference of noise. The estimated target acceleration was used in the guidance law and made it a three-dimensional nonlinear guidance law. The designed guidance law has better guidance performance than Augmented Proportional Navigation Guidance (APNG) and the other two nonlinear guidance laws for intercepting high-speed maneuvering targets.

The technique for building multi-sensor coalitions is studied.With consideration of the precision and energy consumption requirements for single target detection,the specific process for building multi-sensor coalition is presented,and the model of the multi-sensor coalitions is built up.The wolf pack algorithm is introduced and improved to seek the optimum multi-sensor coalition scheme.The simulation result indicates that the process of building multi-sensor coalitions is feasible,the model is rational,and the algorithm is effective.

In order to solve the problems that nonlinear static output feedback H∞control design process is complex,and its difficult to obtain the globally optimal solution and so on,a new approach is presented to design the controller.An approach of Sum of Squares (SOS) is used to analyze the H∞performance of polynomial nonlinear system.Taking the system L2 performance as the objective function,Genetic Algorithm (GA) is used to optimize the control parameters.Simulation results show that the designed controller achieves the optimal L2 performance of the polynomial nonlinear system.

Considering the complexity of ARINC661 cockpit display and control system in realizing target symbols,and the heavy workload of DF developer,we studied the user-defined widgets and parameter interfaces on the basis of ARINC661 specification,and designed a new type of display item.It can present complex composite target symbols in accordance with the setting information in the definition files and the configuration information in the UA instruction.The simulation results show that the design is reasonable and reliable,which can greatly reduce the size of predefined symbol library and the workload of DF developer without increasing the CDS memory usage and communication data.It is also convenient for later maintenance.

The probability of flight conflict is increased because of the increasing of flight flow and uncertainty of flight route.Considering the problem of redundant operation caused by a large number of non-related objects,a preprocessing algorithm for use before conflict detection was proposed.The objects within the surveillance scope of ADS-B IN were divided into 26 different regions,and the correlation of the objects with the own aircraft was distinguished by the specialized rule of each region.Then the correlated objects were further processed,while the uncorrelated ones were blocked.Therefore,the calculation burden for estimation of surrounding traffic situation safety was decreased.The processing principle was “safety the first,” and “better false alarm,never missed alarm”.Finally,the necessity and validity of the proposed algorithm were examined by using Monte Carlo experiment.The simulation results showed that not less than 30% of 30 random objects were blocked.The proposed algorithm is effective and accurate for detecting the correlation between targets.

Visual odometer technology is a navigation mode using only scene image information to calculate the motion parameters, which has good development prospects in positioning and orientation of the autonomous intelligent vehicles. In this paper, the main advantages and technical characteristics of vehicle visual odometer system is summarized and the general architecture and application systems are introduced. The development and current status of the crucial technologies of the odometer, such as camera calibration, feature extraction/matching algorithm, and motion parameter estimation, are mainly analyzed. The implementation schemes for high-precision vision odometer system and high-speed visual odometer system are proposed, and the main algorithms involved are described in detail, which may be taken as a reference for visual odometer research.

In order to verify the function of health management of Integrated Modular Avionics (IMA),a method of fault injection through AFDX network is proposed.This method contains a way to configure fault data and a data transmition strategy to solve the mismatching problem between the data rate and the period of the timer on PC.The environment for fault injection is established and the corresponding software is developed.The experiments conducted verifies the validity of the way and the strategy.

The composition and working principle of the airborne laser communication system are introduced,and analysis is made to the key technologies of the system.Based on the characteristics of airborne platform,the airborne laser communication system and the prototypes were designed,which were verified through ground test and distance test.The experimental results show that this system can realize 20 km to 100 km long-distance communication with bit-error-rate lower than 10-6 and communication bandwidth up to 1.25 Gb·s-1/155 Mb·s-1.The performance index can completely satisfy the design requirements.

The detection and recognition capability can be improved by using infrared dual-band imaging to obtain more information.The application of multi-layer Diffractive Optical Elements (DOEs) in infrared dual-band optical system can correct the chromatic aberration and simplify the system structure.Compared with the single-layer DOEs,the multi-layer DOEs have higher diffraction efficiency in wide wave bandwidths.In this paper,the imaging characteristics of multi-layer DOEs are presented,and the design method is given.Based on which,an infrared dual-band hybrid diffractive-refractive optical system is designed.The diffraction efficiency of the double-layer DOE is higher than 98.5% in the working bands of 3.7 to 4.8 μm and 7.7 to 9.5 μm.The simulation result shows that the system has fine imaging quality,and the performance meets the optical system requirements.

The sharing signal of radar-communication integration of Orthogonal Frequency Division Multiplexing (OFDM) with direct information modulation has high autocorrelation sidelobe and thus may degrade the target detection performance.To solve the problem,and to reduce the space and electromagnetic interference of weapon platform of electronic war,a signal sharing form of radar-communication integration based on the DS-OFDM modulation is proposed for implementing better integration of radar and communication.By selecting proper pseudo-random spreading code to spread the spectrum directly for communication data,and increase its autocorrelation,the autocorrelation of the sharing signal is increased,and thus can improve the target detection capability.The wideband ambiguity function of the sharing signal is analyzed emphatically.The theoretical analysis indicates that,the integrated signal has high spectrum efficiency,low probability of interception,and a strong anti-interference ability.The simulation results show that the integrated signal has an approximate thumbtack ambiguity function by selecting an appropriate symbol length,which makes it suitable for implementing the integration of radar and communication.

To design a commonly-used radio navigation signal simulator,and realize the miniaturization and digitization of test equipment of microwave landing system,a programmable and real-time microwave landing system signal simulator was designed based on Field Programmable Gate Array (FPGA).The simulator uses FPGA as the main control chip.Signal parameters are obtained by serial port communication with PC software.Digital baseband signal is generated by FPGA,and signal simulation is realized through the high-performance analog-to-digital converter AD9777 and the broadband quadrature modulator ADL5375.The realization of microwave landing system signal by FPGA is studied thoroughly,including the solution to the difficult problems in FPGA implementation and the key technologies.The design has been verified by Modelsim 10.1a,and the test results show that the design of signal simulator achieves the expected effect.

When the statistical characteristics of the system noise and measurement noise are indefinite,the estimated values of the two kinds of noise based on Adaptive Kalman Filter (AKF) are relevant,which does not conform to the reality,and may lower the precision of the filter.In order to solve the problem,Improved Adaptive Kalman Filter (IAKF) is proposed.The state space equation of a highly-integrated navigation system is built up.Principle of adaptive Kalman filter is introduced,and the reason for the relevance of two kinds of estimated values is given.Based on that,the new algorithm is used to estimate the system noise and measurement noise on-line,and the shortcoming of the original algorithm is overcome.Semi-physical simulation imaging experiment is designed to verify the new algorithm.The result shows that:The estimation accuracy of the improved algorithm with unknown system noise and measurement noise corresponds to that of the original algorithm with known system noise and measurement noise,which verifies the feasibility of the improved algorithm.

Aiming at the problem of self-stabilizing flight and trajectory tracking control for quadrotor aircraft, a multi-modal sliding-mode attitude control and a new back-stepping recursive trajectory tracking control method are proposed. Firstly, the kinematics equation is established according to Newton's Second Law and Euler's Equation. Considering the serious coupling between the outer loop position tracking control and the inner attitude, the outer loop position controller adopts the new inverse method, which is simple, effective and easy for engineering application. To the inner loop attitude control, a switching type sliding mode control law is designed based on the multi-slide-mode design concept by combining the characteristics of linear sliding mode with nonsingular terminal sliding mode. This control law allows the system state to run in the optimal mode while ensuring that the system's arrival time and sliding time are limited, thus fast global convergence is realized. Simulation results show that the designed controller can quickly track the desired attitude and trajectory and has good control effect.

To guarantee high image quality of astronomical observation,high-precision stabilization system is needed for space telescope.The control of Large-Aperture Fast Steering Mirror (LAFSM) is the key for realizing precise image stabilization,whose performance determines the boresight stabilization accuracy of the space telescope.Both Internal Model Control (IMC) and H∞ are employed to design a compound control system, and an analysis is made to its controlling performance.The simulation results show that the controller has strong stability and robustness.

The unmanned helicopter is a special unmanned aircraft with a broad application prospect.However,the unmanned helicopter itself is a multivariable,nonlinear control system with strong coupling and many uncertainties.In this paper,the mathematical model of unmanned helicopter is presented,and a conventional sliding mode variable structure controller is designed at first.Then,a reaching law based sliding mode controller is designed to depress the chattering of the conventional sliding mode controller.Simulation experiment is carried out finally.The experimental results indicate that the reaching law based sliding mode controller has a better tracking effect than the other controllers on collective pitch angle control,and is effective for chattering attenuation,which can ensure the sliding mode dynamic quality.