In dynamic uncertain environment, the security and reliability of UAVs executing missions can be improved greatly by taking the mobility of the threatening obstacle and the detection error of sensors onboard the UAVs into consideration. On the basis of 3-D velocity obstacle model, the dynamic uncertainties is expressed by the orientation error of threatening obstacle's velocity, and the 3-D Dynamic Velocity Obstacle Model (3-DDVOM) is established. A 3-D dynamic uncertain autonomous collision avoidance algorithm based on 3-DDVOM is presented. Finally, the proposed 3-D autonomous collision avoidance method for UAV is applied to online path planning of Pythagorean Hodograph (PH) curve, and the simulation results show the effectiveness and feasibility of the method.

Threat assessment to the target of ballistic missile is an important part in anti-missile defense,which can provide scientific references for missile defense decision-making.To assess threat degree of the targets effectively,an index system is constructed and 7 kinds of important evaluation indicators are given.Then each indicator is analyzed in detail.On this basis,a new threat assessment method is proposed based on TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) and grey correlation degree,which makes full use of the advantages of two methods.Finally,it is simulated and verified in the typical scenarios.The results show that the threat evaluation method can give comprehensive assessment result of target threat degree,which has certain application value in anti-ballistic missile defense system.

When used in four-rotor aircraft control,the traditional linear discrete sliding mode has the shortcomings of large tracking error,low response speed,and long convergence time.Aiming at the four-rotor aircraft with outside interference,system uncertainties and modeling errors,we proposed a discrete adaptive terminal sliding mode control method based on disturbance observation compensation.First,the terminal sliding mode control law was designed to the discretization equation including the four-rotor aircraft model,and an adaptive law factor was introduced to decrease the chattering.An improved discrete disturbance observer was constructed by taking the square of the state variables as interference error convergence,and its stability was proved.The improved discrete disturbance observer was used to get high-accuracy estimation of the unknown interference,uncertainties and modeling errors,which were used for compensation in controller design.Thus the robustness was increased and the steady-state error was decreased.Finally,the proposed method was used for the control of four-rotor aircraft.Simulation on Matlab shows that:Compared with the discrete terminal sliding mode controlling method,this method has a faster response speed,better tracking effect,and higher robustness,which can implement stable attitude control of the vehicle in the presence of uncertain disturbance.

Aiming at the low reliability for single moment discrimination of multi-range-false-target,a method based on dimensions of space and time characteristics is proposed to discriminate the multi-range-false-targets.Firstly,measurements from radar network are transformed to the earth-centered earth-fixed coordinate system by preprocessing in order to unify the coordinate system.Then,test statistics are built up based on space distribution characteristics of the true-false targets for preliminary discrimination of the true-false targets by single moment association test.Finally,the tests of multiple moments are accumulated for improving the reliability of discrimination.The simulation results verify that:Compared with the single moment test,the accumulation of multi-moment tests is able to improve the reliability of multi-range-false-target discrimination.

A rapid transfer alignment method for missile MEMS SINS is presented.An error model of velocity+attitude information matching method is constructed,and a discretization way of continuous systems easy for engineering application is proposed.Through flutter maneuvering during the alignment procedure,the azimuth estimation accuracy is improved in the scheme.At the same time,in view of the large bias of MEMS inertial sensor,the residual zero offset of gyro is taken as the stage of filter for real-time estimation and compensation.The alignment precision is improved greatly through real-time feedback correcting of attitude and velocity.The flight test results show that the attitude accuracy is better than 0.15°,azimuth accuracy is better than 0.2°,and alignment time is less than 60 s,which can meet the tactical weapon requirements.

Based on the analysis to detectability of target maneuvering,an Unscented Kalman Filter (UKF) model is established for locating and tracking the target with bearing-only small maneuvering.By using the least squared method together with UKF,the locating and tracking of acoustic target with small maneuvering is realized.Simulation result verifies the validity of the method.

As to polarimetric radars with vector measurement,the optimal estimation of the target scattering vector under clutter background is studied.Taking the minimized mean square error of the target scattering vector estimation as the criterion,the optimal estimation to the scattering vector based on transmit polarization optimization is formulated.An algorithm is proposed to optimize the transmit polarization based on sequential estimation scheme.Numerical simulation results demonstrate the effectiveness of the proposed algorithm,and show that the performance of transmit polarization optimization is superior to that of the conventional polarization design.

Considering the terminal guidance problem with impact angle constraint and overload constraint,an Adaptive Fuzzy-Sliding Mode Control (AFSMC) guidance law is presented.Its stability is proved by Layapunov stability criterion.The desired impact angle is defined by a desired Line of Sight (LOS) angle,and achieved by design of sliding mode surface.The Adaptive Neuro Fuzzy Inference System (ANFIS) is introduced to reduce the high-frequency chattering of sliding mode control.Since the ANFIS has a powerful self-learning ability,it is applied to adaptive update the additional acceleration command.As a result,the guidance law has good robustness to uncertain chattering and model uncertainty,and the guidance accuracy is improved.Simulation results show that the AFSMC guidance law can meet the requirements of impact angle constraint,overload constraint and miss distance constraint in various scenarios.

The Unscented Kalman Filter (UKF) and Cubature Kalman Filter (CKF) are introduced,and ananalysis is made to their similarities and differences.Through Monte-Carlo simulation tests,the characteristics of UKF and CKF under large azimuth misalignment are studied,and the following conclusions are obtained:1) UKF is sensitive to both angular motion and linear motion,while CKF is only sensitive to linear motion;2) Both the incentive of angular motion and linear motion can speed up the convergence of UKF algorithm,but as to the CKF,the incentive of angular motion makes no contribution to the alignment accuracy while the incentive of linear motion can speed up the algorithm convergence;and 3) The CKF algorithm accuracy can be gradually increased with the improvement of the incentive of linear motion.The unique characteristics are helpful for the engineering realization of alignment technology.

In recent years,some scholars introduced dynamic Allan variance into the random signal processing of inertial components to implement real-time tracking of random signal error.However,since the dynamic Allan variance uses the function with fixed window length for intercepting random signals,it can not guarantee both the signal dynamic tracking performance and variance confidence level.To solve the problem,this paper proposes a dynamic Allan variance arithmetic based on entropy of information.First,the entropy of information in the window is used for representing the non-stationarity of the dynamic gyro signal.Then,it can adaptively select the appropriate window length for the next moment according to the entropy of random signal,and calculate the Allan variance of the signal.Simulation result proves that the algorithm can effectively improve the real-time tracking capabilities of the gyro dynamic signal.

In order to improve the operational capability of aircraft weapon,FC network shall be applied in high speed up/down communication paths of the aircraft/store.The relations of FC network standard of Aircraft/Store (AS5653) with FC-AE-1553,FC-AV,FC-FS,and FC-SW are presented.The composition and main technical requirements of AS5653 are studied.The key technologies in aircraft/store FC network design,including network topology and port layout,communication modes,network initialization and high-level protocol,are also analyzed,which can be taken as a reference for development of FC network in aircraft/store.

Array antenna sharing design can significantly improve the utilization efficiency of the antenna.The current array antenna design focuses on two or more radar array.In addition,if radar array and communication array elements are in interleaved arrangement based on sparse array technology,the integration of radar and communication will be implemented.Firstly,based on cyclic difference sets theory,sparse array radar is established,and the sparse array radar antenna pattern is analyzed.Meanwhile,the untaken array elements are remained for communication.Secondly,a further array arrangement is executed to improve communication channel gain based on the channel rank deficient effect.Finally,technical indicators of the radar and communications integration antenna are simulated and analyzed,which verifies the effectiveness of the proposed method.

Modeling on the basis of reliability theory of multi-state element overcomes the shortage of traditional binary reliability model of information loss,and improves the accuracy of assessment.The existing models mainly focus on the analysis of elements with gradual failures.After Markov processing is introduced,definition of multi-state element is given in detail.The continuous-time Markov processing in element state-transition is described,based on which the state-transition reliability models for both gradual failures and mutational failures of elements are proposed.Taking the delay valve of a certain type of missile as an example,the state-transition differential equations with gradual failures and mutational failures happening simultaneously are established,and the reliability functions of the delay valve at a certain demand level are determined.The reliability of the element at determined moment is obtained,which can supply a reference for making maintenance and support decisions.

According to the specific functions and characteristics of airline network,two new measurements for network survivability were put forward.The transport reliability measurement was given based on network throughput taking the flow as the Edge Weight (EW).The accessibility measurement was proposed based on the link situation among nodes,which can accurately reflect the network connectivity.At last,simulation was carried out to verify the two proposed measurements by using two attack models based on incomplete information conditions.The result shows that:1) Under EW attack strategy,the network has a bad transport reliability,and the transport reliability decreases more quickly and obviously as the acquired information quantity increases;While the accessibility behaves well,and it shows a trend of slow descent as the acquired information quantity increases;and 2) Under Unweighted Edge Betweenness (UEB) attack strategy,the network has fine transport reliability and accessibility,but the response to the acquired information quantity is different:The transport reliability hardly changes as the acquired information quantity increases,while the accessibility has a certain acceleration of descent.Therefore,the two measurements can reflect the survivability under two attack strategies from two aspects,and have a good ability for measurement,which verifies the method.

Infrared Search and Track (IRST) system is an optical imaging detection equipment used widely onboard the aircrafts.A method for evaluating the detection distance of IRST system is presented here,which is adaptive for use in the lab.Taking the target irradiance as the index,and by using a measurement system to accurately simulate the target irradiance,the evaluation of IRST detecting distance is transformed into the measurement of target detection sensitivity.We made test to multiple IRST products in the lab under the same conditions,and carried out the evaluation to the detecting distance through analogy analysis.The result shows that the method is simple and efficient.

To the issue of joint estimation of the extended targets shape and kinematic state, a Gaussian mixture PHD filter based on star-convex Random Hypersurface Models (RHM) is proposed for extended target tracking. The proposed algorithm describes the extension of measurements by the star-convex RHM and uses the sampling constraint to limit the shape parameters of targets. Then, under the Gaussian mixture probability hypothesis density framework, the extended targets are tracked by calculating and updating the likelihood and new information. Simulation results show that the proposed method can guarantee the availability and feasibility of the tracking and improve the accuracy of extended target kinematic state and shape estimation.

To the issue of joint estimation of the extended targets shape and kinematic state,a Gaussian mixture PHD filter based on star-convex Random Hypersurface Models (RHM) is proposed for extended target tracking.The proposed algorithm describes the extension of measurements by the star-convex RHM and uses the sampling constraint to limit the shape parameters of targets.Then,under the Gaussian mixture probability hypothesis density framework,the extended targets are tracked by calculating and updating the likelihood and new information.Simulation results show that the proposed method can guarantee the availability and feasibility of the tracking and improve the accuracy of extended target kinematic state and shape estimation.

The distributed structure was used to improve the reliability of unmanned aerial vehicle's flight control computer. To the serial input and output unit that has the biggest data traffic, a redundancy management scheme was designed, which can effectively judge the type of fault and handle the fault. To each unit inside the computer, FlexRay bus protocol was designed from three aspects of time scheduling, redundancy management and data transmission in stagger cycle. FlexRay bus communication test and unit redundancy test were made. The result proves the correctness and practicability of the designed redundancy management method and the bus protocol.

In order to solve the problem of UAV's autonomous landing when GPS signal is failed, a UAV landing method based on FastSLAM algorithm is adopted. First, based on the ground speed measured by Doppler radar, the motion model is described by nonlinear equation with Gaussian noise. The UAV uses its laser radar to obtain the distance and azimuth relative to environmental landmarks for constructing the system observation model. Path estimation and environmental landmark estimation are implemented by particle filter and extended Kalman filter respectively. The velocity estimation is obtained by using tracking differentiator of the arctangent form. Simulation results show that by choosing appropriate number of particles and environmental landmarks, FastSLAM algorithm can meet the requirement on landing precision and real-time performance, and is an effective landing navigation method.

To improve the power supply reliability,the generators of More Electric Aircraft (MEA) Variable Speed Variable Frequency (VSVF) Electrical Power System (EPS) are used as redundant power supplies instead of parallel power supply.To study the steady state operation and power source change strategies under malfunction conditions of VSVF EPS,the integrated structure of VSVF EPS is illustrated and operating principles of components are analyzed.The key components,including variable frequency generators,bus power control unit,rectifiers and other supplementary elements,are then simulated by a comprehensive VSVF EPS model established on the platform of Simulink,and the power source change strategies are realized by logic units.Finally,case study is made for simulation of normal operation state and verification of power source exchange under malfunction state.

In order to achieve fast initial alignment of Strap-down Initial Navigation System (SINS) with gyros information under circumstance of disturbance and strong noise,Quasi-Equality Constrained Kalman Filter (QECKF) was introduced,based on which the model of SINS initial alignment was established.According to the characteristics of the SINS onboard land vehicles,it was proposed to use IIR low-pass filter at first for noise reduction,then the filtering method of QECKF together with KF.The scheme made full use of the gyro information,and could realize fast initial alignment.Result of the test under disturbance of engine and operators showed that the speed of the algorithm was increased by 25% compared with the normal KF.The algorithm solved the problem of estimation divergence of the normal method.

To solve the inefficiency and high cost problems of the traditional detection equipment,an airborne receiver detector was developed for Instrument Landing System (ILS).Taking the DSP+FPGA architecture as the core,the circuit system of the ILS airborne receiver detector was composed together with the circuits of peripheral signal synthesis,interface converters,analog sampling and human-computer interaction.Such problems as signal simulation of instrument landing ground station,the ARINC429 protocol conversion based on FPGA,the design of detection strategy and data analysis based on DSP,were solved.The detector is able to detect the ILS airborne receiver,which is easy and flexible to use.

Considering that GNSS satellite receiver is easy to lose stars in high dynamic situation or in urban canyons,and GNSS satellite receiver may fail in the case of signal interference,we designed a fault-tolerant SINS/GNSS integrated navigation system.In this paper,the design scheme of the fault-tolerant integrated navigation system is described in detail.The various types of abnormalities that may occur are analyzed,and the appropriate treatment strategies are given.The fault-tolerant integrated navigation method can improve the reliability and the accuracy of the system in case that GNSS satellite receiver is abnormal.The simulation test and vehicle test designed for the fault-tolerant SINS/GNSS integrated navigation system achieved good results.