In signal detection of Airborne Early Warning (AEW) radar under actual combat environment, the object signal must contend against sidelobe clutter, noise and jamming.The ratio of signal to the sum of sidelobe clutter, noise and jamming determines the operating range of the AEW radar, in which the sidelobe clutter power calculation is most difficult under different terrain and different PRF working model.Considering the benefit of the radar signal processing, we derived the universal formula of sidelobe clutter power calculation based on the analysis of ground and sea clutter characteristics.The operating range equation of AEW radar under the clutter and jamming environment was also given.The simulation results demonstrate the correctness of the sidelobe clutter power calculation formula and the operating range equation.

A novel nonlinear robust control scheme is proposed for a morphing vehicle with unknown uncertainties and external disturbance.An online adaptive compensation algorithm is designed for approaching the disturbance item, and the parameter updating law is used for providing automatic disturbance rejection ability in real time, which improves the robustness of the system.Then, by adaptively adjusting the weighting parameters of the hidden layer of neural network, the output of the neural network is made to approach the uncertain item.It is proved by using the Lyapunov stabilization theory that the robust controller can make the tracking error asymptotically stable.An online updating law is also designed for parameters of the controller.Simulation results show the effectiveness and feasibility of the approach.

Identification of ballistic missiles contains many aspects, and the identification of launching symptom is an important part of it, which determines the subsequent detection probability of ballistic missile by early warning satellite and the warming time.In this paper, a synthetic method for identification of ballistic missile launching symptom is proposed based on Dynamic Bayesian Network (DBN).Firstly, four kinds of symptom features are selected and the conditional probability of each feature is given.Then the DBN model of symptom identification is established and the identification process is designed.At last, it is verified by simulation that the model is much better and more robust than the method using single feature.The study shows that the method can fuse multiple kinds of features at different time, and give a scientific and reasonable symptom identification result.

The flight ability in the forward flight phase is the basis of the over-the-horizon flight of unmanned helicopter, and crosswind is the most important factor affecting the helicopter safety in forward flight phase.Therefore, the strategy of resisting lateral wind in the forward flight phase restricts the ability of the over-the-horizon flight of unmanned helicopter.At present, the main strategies of UAVs are the side-slipping method and the crabbed method.Side-slipping method resists the lateral force on the plane by crosswind through plane rolling.Using this method the unmanned helicopter flies with the sideslip.Crabbed method eliminates the sideslip through turning the heading to airspeed direction.The unmanned helicopter flies without the sideslip with this method.Four schemes are designed for crosswind resisting according to the two strategies, and comparison and analysis are carried out for meeting different engineering requirements respectively.

Mission planning is one of key technologies for Unmanned Aerial Vehicle (UAV) cooperative combat. For the task of suppressing the enemy's aerial-defense firepower, we established a mission planning model for multi-UAV cooperative attacking multiple ground targets by taking terrain and threat distribution, firepower resource needed to destroy the targets, and damage probability of UAVs into consideration. A parallel Genetic Algorithm and Particle Swarm Optimization (GAPSO) algorithm was proposed to resolve this multi-UAV cooperative mission planning problem. Simulation example verified the rationality of the mission planning model. The comparison between parallel GAPSO algorithm and traditional GAPSO algorithm showed that the parallel algorithm has better convergence performance and could avoid trapping in local optimum.

Periodic Event Triggered Control (PETC) is suited for applications where communication resources are scarce.As a new control strategy, the system theory in modeling and analysis of PETC is far from being mature.In this paper, Input-to-State Stability (ISS) theory is employed to analyze the linear state feedback periodic event triggered control systems.At first, the linear state feedback PETC system is considered as a discrete-time perturbed system, then the stability theorem of event triggered control system is deduced based on ISS theory of discrete-time perturbed systems, a Linear Matrix Inequality (LMI) form of the theorem is also given.At last, a method to determine event-triggering threshold is derived.Matlab simulation result verifies the correctness and effectiveness of our methods.

This paper describes an envelope protection control system using obstacle-avoidance method for the new generation fighter.Firstly, a dynamic inversion controller is used to stabilize the fighter.Obstacle avoidance boundary protection method is then developed to generate the security envelope of the key flight parameters.The Dynamic Matrix Control (DMC) adjusts its parameters online to modify the control variables of the fighter.The developed dynamic matrix control scheme can guarantee the fighter flying inside the security boundary.Simulations are provided for angle of attack, and the simulation results show that the designed flight control system is effective.

The trajectory control of aircraft when encountering low-altitude windshear in approaching is studied.A realistic engineering model of windshear and a nonlinear mathematical model of aircraft are established.Singular perturbation theory is applied to divide the dynamic system into several simple subsystems, and the Nonlinear Dynamic Inversion (NDI) method is employed for designing the control law for slow-state/fast-state subsystem and guidance system of outside loop.PID control method is also adopted for compensating the system inversion error arising from the perturbation of aircraft aerodynamic parameters caused by windshear and other exterior factors, which effectively eliminates steady state error of the system and keep effective control to the flight path of aircraft approaching.Finally, the simulation results indicate that the proposed NDI-PID controller has good dynamic characteristics and robustness, which can effectively resist the windshear interference with certain strength.

A single submarine must maneuver at high speed to carry out bearing-only target tracking passively.To solve the problem, a new method is proposed for a submarine to track a target stealthily by cooperation with Unmanned Underwater Vehicle (UUV).The UUVs are arranged at some distance away from a submarine, which communicate with the submarine by optical fiber.The command and control system of the submarine tracks the target by using observations of the submarine and UUVs, by which submarines can track target stealthily without making high-speed maneuvering.Results of simulations prove that the method has better tracking performance.

Since the number of available combinations is limited and the combined integer ambiguities are difficult to fix, an algorithm for direct calculation of BDS single-frequency integer ambiguity based on dual-frequency correlation constrains is proposed.On the premise that a combined integer ambiguity is fixed correctly, the single-frequency integer ambiguity can be calculated by the agency of the fixed combined integer ambiguity according to the correlation between B1 and B2 double differential equation, then margin of error of single-frequency integer ambiguity is determined through mean square error of the fixed combined integer ambiguity.Finally, the correct single-frequency integer ambiguity can be obtained through adaptive threshold OVT test method.The experiment results reveal that, when mean square error is less than 1/4 of wavelength, the algorithm can calculate B1 and B2 single-frequency integer ambiguity correctly with only one combined integer ambiguity, which means that the proposed algorithm is suitable for kinematic to kinematic high-precision relative positioning.

Considering that it is difficult to make threat assessment in anti-TBM (Tactical Ballistic Missile) combat with incomplete index information by using the existing threat assessment methods, a threat assessment method based on Evidential Reasoning (ER) was proposed.First, the threat assessment factors of TBM in boost phase were analyzed, the hierarchical structure model for threat assessment was constructed, and analysis was made to the issue of incomplete index information.Then, the ER method was applied to conduct threat assessment in anti-TBM combat with incomplete index information, and the detailed steps of the method were put forward.At last, analysis of examples showed that the proposed method can deal with the threat assessment problem in anti-TBM combat effectively.

To suppress speckle noise effectively and protect edge details, a method for speckle noise suppression is proposed based on homomorphic filtering and the improved threshold integer lifting wavelet transform.Firstly, the homomrphic filtering is used for converting the multiplicative speckle noise into additive noise, and the integer lifting wavelet transform is used to decompose the image.Then, according to analysis to the shortcomings of the traditional wavelet threshold function, a new threshold function model and an adaptive threshold calculation method are designed, and threshold processing is made to the coefficients of the wavelet decomposition.Finally, inverse wavelet transform and inverse homomopgic transform are carried out and the denoised image is obtained.Simulation experiments show that the proposed algorithm can not only suppress the speckle noise effectively, but also protect the edges properly, thus it has good practicability.

To civil aircrafts, safety is the most important.The Flight Management System (FMS) is an airborne equipment essential to guarantee the flight safety of the civil aircraft.Under the deception jamming to GPS, the safety of the FMS navigation determines whether the aircraft can fly safely in the designated airspace or not.Taking a certain foreign FMS as the object for test, we established a test platform and made experiments to study the effect of GPS deception jamming signals on FMS navigation safety.The study supplies a basis and technical support for improving the safety level in FMS development.

The 3D terrain visualization is one of the most important technologies of Synthetic Vision System (SVS).Considering that the airborne SVS has the characteristics of large-scale terrain scene, less computing resource and rigorous real-time requirement, we studied such critical technologies as scheduling of terrain blocks, levels of detail, and texture generating.Based on which, a 3D terrain visualization system suitable for SVS was designed and implemented.The experimental results showed that our terrain visualization system satisfies the requirement of SVS both in visual effect and real-time performance.

Switching equipment of the Time-Triggered Ethernet adopts central monitoring system to check the integrity of communication.But for a hierarchical TTE network with gateway, a communication integrity security mechanism on system level should be realized at the gateway.Based on general topological structure, this paper presents a gateway with communication integrity check function, combining the external redundancy physical link with the internal protocol check.A semi-physical simulation platform is constructed to verify the design mentioned.The results indicate that based on the full use of the equipment-level integrity check function, this design is compatible with both ends of the network transmission and can support system-level fault isolation effectively.

The traditional active contour model is sensitive to initial contour and noise, and is unable to extract multiple targets.To solve these problems, a novel minimum variance active contour model is proposed based on generalized likelihood ratio.The generalized likelihood ratio information is introduced to a region-based active contour model.A novel energy function is designed under the criteria of minimum variance between the target area and background area, which is then minimized by using a gradient descent method to drive the contour shrinking to object borders.Experimental results on synthetic and real images prove that the proposed model is not sensitive to the initial contour position or noise, and is adaptable to multi-target scenario.

The pilots'cognitive states are essential factors affecting their control performance to the flight control system. Generally, cognitive states can not be measured directly. However, they can be gained indirectly by the means of physiological signals. Based on the characteristics of the physiological signals in time frequency domain, wavelet analysis is used for establishing the feature sets, and an FPA optimized Gaussian Process (GP) model is proposed for classification based on flower pollination algorithm, which is used for analyzing the pilots'cognitive states in a full flight simulation. Through the comparison between the classification results and the NASA-TLX test result of the pilots, the validity of this method is verified.

For the pilot-aircraft system with pilot model concerning human factors, traditional control methods on specific models cannot totally satisfy flight trajectory precision.An unfalsified PI controller design method based on fading memory and linearly increasing cost level algorithm is introduced for such pilot-in-loop system.Unfalsified adaptive control theory is a non-model data-driven control theory, which only uses model input and output data.In the unfalsified control theory, the supervisor selects the best controller and the controller switching algorithm switches controllers when necessary.Fading memory method decreases the impact on switching algorithm which is caused by old data.Monte Carlo simulation is made in designed flight scenario.The result indicates that the designed controller improves the flight performance.

The paper introduces the composition and operational process of weapon system of the tripod-launched missile by several soldiers.The error propagation model is proposed, and each error source is introduced briefly.The mathematic model is presented for accuracy analysis to the weapon system.A computing example is given based on actual operational requirements and technological levels of the system/equipment.The calculation result proves the reasonability and effectiveness of accuracy analysis model and the error allocation scheme.The paper provides a support for design and demonstration of the weapon systems target acquisition probability.

Mean Shift algorithm works well locally and is used to track the objects with low speed.But the algorithm is easy to fall into local maximum due to lack of appropriate target model updating mechanism.In this paper, a new Mean Shift algorithm based on SIFT Verification is proposed, which can be used for tracking the occluded object moving at high speed.The proposed algorithm can compensate for the shortcoming of the Mean Shift while keeping fine real-time performance.Tests were made to the scenes of occluded vehicle moving at high speed with comparison to the traditional algorithms.The experimental results show that the proposed algorithm can effectively track an object under the complex condition with fine real-time performance and high robustness.

In order to improve the accuracy of the pedestrian detection, identification and tracking, a pedestrian tracking algorithm is proposed based on human body characteristics identification and Kalman filter.The algorithm uses the recognition method that is based on the human body feature and behavioral characteristic gesture to automatically identify pedestrians.Behavioral characteristic gesture recognition algorithm uses a front and rear frame pixel probabilistic matching algorithm with Gaussian mixture model, and improves probability of success for human recognition by using human body features.Then, a histogram of oriented gradients is used for characterization of target detection.Finally, the target moving trajectory is predicted by Kalman filter.Experiment was made to the two infrared pedestrian detection and tracking methods, and the result showed that, the algorithm can more accurately capture the human target from moving object for real-time tracking.