
By taking carrier based aircraft as the studying object, we set up the dynamic model and design a carrier based aircraft automatic landing control system based on the H2 full information preview controller, which can suppress the interference caused by carrier air wake movement and track the landing glide slope. Taking a certain type of carrier based aircraft as the controlled object, a non linear numerical simulation is made. The results show that: 1) the H2 full information preview control strategy can improve the effect of rejecting air wake interference, obtain a quicker system response and a satisfactory trajectory tracking effect;and 2) the control effect is better than that of PID control.
The fuel consumption performance of aircraft is directly related to the deployment capacity and profitability of airline. According to the actual aircraft flight data, we established an exponential attenuation function model of aircraft fuel consumption performance. Based on the feature that the attenuation speed varies with each component of fuel consumption performance, the GIP algorithm of NHD and RELAX algorithm were introduced to realize the separation and parameter estimation of each component of fuel consumption model. The CRB analysis of the experiment results proved the accuracy of the parameter estimation, and the A330 flight data proved the effectiveness of the algorithm. This method provides a reference criterion for aircraft fuel consumption performance evaluation.
Considering-the-operational-application-and-the-characteristics-of-equipment-performance, and-based-on-the-analysis-to-the-horizontal-reconnaissance-scope-and-the-precise-direction-finding-zone-of-dual-shipborne-UAVs, models-of-dual-aircraft-feasible-locating-area, dual-aircraft-effective-precise-location-area-and-maximum-inscribed-rectangle-in-dual-aircraft-effective-precise-locating-area-were-established, and-the-relationship-between-dual-aircraft-effective-precise-locating-area-and-equal-circular-error-probable-curve-was-analyzed. Practical-conclusion-was-obtained-by-simulation, which-provides-a-decision-making-basis-for-optimal-configuration-of-search-power-when-destroyer/frigate-formation-adopting-dual-UAV-passive-locating.
Considering the operational application and the characteristics of equipment performance, and based on the analysis to the horizontal reconnaissance scope and the precise direction finding zone of dual shipborne UAVs, models of dual aircraft feasible locating area, dual aircraft effective precise location area and maximum inscribed rectangle in dual aircraft effective precise locating area were established, and the relationship between dual aircraft effective precise locating area and equal circular error probable curve was analyzed. Practical conclusion was obtained by simulation, which provides a decision making basis for optimal configuration of search power when destroyer/frigate formation adopting dual UAV passive locating.
Time Triggered Ethernet (TTE) provides extended time triggered communication supports over Ethernet MAC layer for distributed real time mixed criticality systems. A suite based object oriented model for TTE elements was analyzed and a simulation software tool was constructed, which can simulate different kinds of critical real time mixed criticality flows in a typical scenario of avionics system. The performance analysis of end to end delay bounds from simulations prove that TTE can provide different levels of proper real time guarantees based on characteristics of flows.
In order to improve the reliability and matching precision of scene matching navigation system, a novel fusion algorithm is proposed based on Position Difference Filtering (PDF) and Least Squares Estimate (LSE) for dynamic scene matching. The essence of the matching results fusion problems for aircraft dynamic scene matching navigation system is analyzed. Then, according to the error characteristic of matching position point sequence, PDF method is designed to filtering the mismatching points, and LSE method is used for optimum parameter estimation, thus the mismatching points are estimated and the matching position are predicted. Furthermore, the principle and flowchart of the fusion algorithm are given. Simulation experimental results show the feasibility and availability of the proposed algorithm in eliminating the mismatching points and random matching disturbance for dynamic scene matching navigation system.
Because the near-space hypersonic vehicle's flight trajectory is unknown and its motion mode is varying during the flight, the traditional single tracking model algorithm may mismatch targefs motion and thus decrease its tracking precision. As for the target^ slippage leap maneuvering, an Interacting Multiple Model (IMM) algorithm based on CV model, CA model and sine wave model was proposed for tracking vehicles with such kind of maneuvering. The results of Monte Carlo simulation experiments show that: compared with the IMM algorithm based on CV-CA-Singer model and the IMM algorithm based on CV-CA- CA model, the IMM algorithm proposed here has better tracking performance to near space hypersonic target with slippage leap maneuvering.方向为机动目标跟踪与信息触合。
Because the near space hypersonic vehicles flight trajectory is unknown and its motion mode is varying during the flightthe traditional single tracking model algorithm may mismatch targets motion and thus decrease its tracking precision.As for the targets slippage leap maneuveringan Interacting Multiple Model(IMM) algorithm based on CV modelCA model and sine wave model was proposed for tracking vehicles with such kind of maneuvering.The results of Monte Carlo simulation experiments show that:compared with the IMM algorithm based on CV CA Singer model and the IMM algorithm based on CV CA CA modelthe IMM algorithm proposed here has better tracking performance to near space hypersonic target with slippage leap maneuvering.
Corner reflector interference is a common passive interference faced by active radar seeker. Therefore, the anti interference method is an important supporting technology for active radar seeker of anti radiation missile to precisely attack the target. A waveform selection based method is proposed for radar seeker to counter the corner reflector interference. Firstly, a brief analysis is made of the radar characteristics of corner reflector, and then a criterion of maximum information distance is proposed as the criterion for waveform selection. The principle is as follows: in the case that radar launches LFM (Linear Frequency Modulation) signal, SF LFM (Stepped Frequency Linear Frequency Modulation) signal and BPSK (Binary Phase Shift Keying) signal, take the maximum information distance between the attacked target and one dimension high resolution range profile of the corner reflector as the optimal function, select one of the three signals to distinguish the target and corner reflector, thus to realize anti corner reflector interference. Simulation results show that the proposed algorithm has good performance.
A dynamic inversion control method of super maneuverable aircraft is studiedwhich is based on sliding mode observer using Super twisting algorithm and PI.Firstlyanalysis is made to the super maneuvering aircrafts nonlinear characteristic with consideration of the thrust vectorand a nonlinear simulation platform of the aircraft is established.In the fast loopthe direct external disturbance torque is estimated using sliding mode observer of Super twisting algorithm and then the compensation control law is designed for interference suppression.In the slow loopthe classical PI control is used to offset the system inversion error caused by the nonlinear cancellation.Finallythe control law is used in the cobra maneuver of large angle of attack.The simulation shows that the designed control law can make the super maneuverable aircraft have a good rapidity and stability.
A dynamic inversion control method of super maneuverable aircraft is studied, which is based on sliding mode observer using Super twisting algorithm and PI.Firstly, analysis is made to the super maneuvering aircrafts nonlinear characteristic with consideration of the thrust vector, and a nonlinear simulation platform of the aircraft is established.In the fast loop, the direct external disturbance torque is estimated using sliding mode observer of Super twisting algorithm and then the compensation control law is designed for interference suppression.In the slow loop, the classical PI control is used to offset the system inversion error caused by the nonlinear cancellation.Finally, the control law is used in the cobra maneuver of large angle of attack.The simulation shows that the designed control law can make the super maneuverable aircraft have a good rapidity and stability.
In order to solve the restoration problem of images with radial blur and random vibration blur, which is caused by EO payload imaging in high speed motion, a physical model of hybrid blurred image is established by using the sub image blur kernel function extension estimation step by step, to improve the RL TV recursive model and complete the restoration of hybrid blurred image. The results show that the hybrid blur kernel function is a superimposition of the vibration vector and radial vector in time of exposure, and the simulation effect conforms with the actual measured effect. In the hybrid blurred image, the radial blurred features gradually attenuate from the edge to the center, and the central area of image can approximately estimate the vibration blurred kernel function. By using a center to edge sub image hierarchical recursive method, the hybrid blurred image can be effectively restored, with much better effect than other restoration methods, such as sequence restoration.
In order to better reflect and meet the actual operation and flight demand of multi motor unmanned helicopter, the problem of attitude control for the helicopter with flight state constraints is discussed, taking into consideration of uncertain and external disturbance factors. Firstly, the mathematical model of the unmanned helicopter is given by Newton Euler formulas. Secondly, a SMDO disturbance reconstruction algorithm is designed to reconstruct the unknown compound interference in the attitude system and to design the compensation control law. Thirdly, in order to address the state constraints and avoid the differential expansion in design of back stepping controller, an attitude controller based on the SMDO disturbance compensation and constrained command filter is designed. Finally, the correctness of the designed algorithm is verified through simulation experiment.
It is of high theoretical value and practical significance to study multi UAV cooperative path control strategymaking it support multi UAV attack on multi target coordinatelyand control the UAVs to arrive the target location at the same or given time in order to maximize the operational effectiveness.The coordination strategy of multi level distributed control architecture is determined.The concepts and the corresponding expressions of coordination variable and coordination function are presentedand the communication relation between lead plane and wing planes is given.Finallythe problem of multi UAV coordinated path control with time constraint is solved by using multi level distributed coordination strategies based on coordination variable and coordination function.Simulation results verify the effectiveness of the algorithm.
It is of high theoretical value and practical significance to study multi UAV cooperative path control strategy, making it support multi UAV attack on multi target coordinately, and control the UAVs to arrive the target location at the same or given time in order to maximize the operational effectiveness. The coordination strategy of multi level distributed control architecture is determined. The concepts and the corresponding expressions of coordination variable and coordination function are presented, and the communication relation between lead plane and wing planes is given. Finally, the problem of multi UAV coordinated path control with time constraint is solved by using multi level distributed coordination strategies based on coordination variable and coordination function. Simulation results verify the effectiveness of the algorithm.
In target recognition, the use of Dempsters rule for conflict evidence fusion may result in unreasonable conclusion. To solve the problem, we proposed a weighted Mahalanobis distance based method for improving the evidence theory. Before the application of evidence theory, the evidences were preprocessed and the support degree of each evidence was calculated out by introducing weighted Mahalanobis distance. The conflict evidence was superseded by average evidence and the weight of evidence was obtained by support degree. Then the evidences were fused by evidence theory combination rule to recognize the target. In simulations, the proposed method was compared with the existing combination methods, and the result shows that this method is more effective in combining conflict evidence than the others.
In order to locate weak target with sub pixel precision under strong noise condition, a sub pixel edge detection algorithm was proposed based on improved wavelet transform and Zernike moments. Firstly, wavelet transform and modulus maxima were combined to search the edge points “from coarse to fine” to achieve accurate and effective locating, then sub pixel edge points were detected by the improved Zernike moments. The method was used for dealing with images with noise in actual engineering application. The experimental result showed that the algorithm has stronger anti noise capability and higher locating accuracy, and it is a stable and reliable algorithm with better performance over that of the traditional edge detection algorithms.
In the air ground frequency selective fading channel, the channel impulse response has the time domain sparse characteristic.In the light of the discovery mentioned above, the greedy algorithm based sparse channel estimation method for Single Carrier Frequency Domain Equalization (SC FDE) system is proposed in this paper.Chu sequence, the pilot sequence commonly used in SC FDE is analyzed, and it is proven that the pilot matrix constructed by the cyclic shift of Chu sequence has satisfied RIP condition.Thus, the pilot matrix is used as a measurement matrix, the air ground channel estimation issue is modeled as a sparse reconstruction model, and sparse reconstruction of the channel is performed with OPM and CoSaMP algorithms of the greedy algorithm.It is verified by simulation that:compared with the traditional Least Squares (LS) channel estimation method, the obtained channel estimation is of higher accuracy.With the same training sequence length and channel environment, the Minimum Mean Square Error (MMSE) equalization of received signal is performed by using the obtained channel estimation.The Monte Carlo simulation results show that compared with the traditional LS channel estimation method, the proposed method can improve the system error performance by 2~3 dB.
The development status of closed loop electro optic countermeasure technology was introduced.In order to obtain the forecast evaluation of photoelectric jamming effectivenessa forecast evaluation model was built up based on BP neural network by analyzing the technical principle and influence factors of laser jamming to optical seekerand some photoelectric jamming experiments were implemented.After the comparative analysis to forecast result and experiment resultthe accuracy of the prediction model was verified.The research can provide an application foundation for feasibility analysis of this method in photoelectric countermeasure.
The development status of closed loop electro optic countermeasure technology was introduced. In order to obtain the forecast evaluation of photoelectric jamming effectiveness, a forecast evaluation model was built up based on BP neural network by analyzing the technical principle and influence factors of laser jamming to optical seeker, and some photoelectric jamming experiments were implemented. After the comparative analysis to forecast result and experiment result, the accuracy of the prediction model was verified. The research can provide an application foundation for feasibility analysis of this method in photoelectric countermeasure.
Airborne network is one of the key technologies of aircraft avionics system. The real time performance, fault tolerance and correctness of network behavior of it will affect the overall performance of aircraft, and a proper management of it will give an effective play to the performance of the avionics system. Based on research for avionics system network architecture, an avionics system architecture module with cascade double CPC was proposed, taking AFDX network as the backbone network. On the basis of which, as well as in combination with the characteristics of AFDX network and method of TCP/IP network management, research on AFDX network management technology was carried out. Methods of AFDX network management and its implementation were analyzed, such key requirements as its architecture management, fault management and configuration management were proposed, and the network management software was implemented in VxWorks653 operating system.
By taking carrier based aircraft as the studying objectwe set up the dynamic model and design a carrier based aircraft automatic landing control system based on the H2 full information preview controllerwhich can suppress the interference caused by carrier air wake movement and track the landing glide slope.Taking a certain type of carrier based aircraft as the controlled objecta non linear numerical simulation is made.The results show that:1) the H2 full information preview control strategy can improve the effect of rejecting air wake interferenceobtain a quicker system response and a satisfactory trajectory tracking effect;and 2) the control effect is better than that of PID control.
Considering the stability of a multi robot system with a specific leader mode, we derived a typical control method for the formation control based on consistency. Lyapunov stability theory and matrix theory were used for deriving the sufficient condition for the multi robot system formation to reach consistency, and the constrains for the system consistency protocol under the condition were obtained. The communication topological relation of the leader mode was set up randomly; the sufficient condition obtained was used for analyzing the convergence performance of the algorithm, and an algorithm satisfying the condition for this mode was presented. Digital simulation result verified the effectiveness of the proposed algorithm.
Application of deep classification networks in classification of typical targets in road traffic is investigated in this paper.Deep classification networks are constructed by combining such target representation methods as original gray level imageHOG feature histogramCanny edge image and eigen features with Deep Belief Networks(DBN)to realize the classification function for four typical targets in road traffic:pedestrianbikervehicles and others in the real scene.In order to assist in training of DBN based deep people/vehicle classification networksan image database of typical road targets called NUPTERC is establishedwith rules and methods for its establishment.And then experiments are constructed with NUPTERC image databaseto test the proposed deep classification networksand a comparison is made with other classification methods for people and vehicles.It is proven that the deep classification networks can achieve satisfactory classification accuracy under the condition of meeting the real time performance.Finallypeople/vehicles classification algorithm based on DBN5Canny is applied to the “cloud platform for intelligent video analysis” developed by our centerrealizing functions of real time accurate analysis and classification of typical targets in road traffic.
Application of deep classification networks in classification of typical targets in road traffic is investigated in this paper. Deep classification networks are constructed by combining such target representation methods as original gray level image, HOG feature histogram, Canny edge image and eigen features with Deep Belief Networks(DBN), to realize the classification function for four typical targets in road traffic: pedestrian, biker, vehicles and others in the real scene. In order to assist in training of DBN based deep people/vehicle classification networks, an image database of typical road targets called NUPTERC is established, with rules and methods for its establishment. And then experiments are constructed with NUPTERC image database, to test the proposed deep classification networks, and a comparison is made with other classification methods for people and vehicles. It is proven that the deep classification networks can achieve satisfactory classification accuracy under the condition of meeting the real time performance. Finally, people/vehicles classification algorithm based on DBN5Canny is applied to the “cloud platform for intelligent video analysis” developed by our center, realizing functions of real time accurate analysis and classification of typical targets in road traffic.
To decrease the influence of resonator eccentricity to output of Hemispherical Resonator Gyroscope (HRG) in force feedback model, three schemes were designed to measure the resonator amplitude. Firstly, based on the dynamic motion equation of resonator in radial direction, the expression of gyros output was established. Then, the amplitude measured by different schemes was inferred in the condition of resonator eccentricity. Based on the amplitude, gyros output corresponding to each measurement scheme was obtained. At last, the output relative error of each scheme was calculated out by simulation. The simulation result showed that the third scheme has the best performance for decreasing the influence of resonator eccentricity to gyros output.
Currently orbit determination for lunar satellite is supported by ground stations for remote telemetry, but the distance between lunar satellites and ground stations is too long, signal delay is large. In order to reduce the dependence of navigation systems to ground based operations and achieve more autonomy, an autonomous navigation for lunar satellite using X ray pulsars is proposed. Combined with lunar satellite orbit dynamics equations and pulsars measurement, we discuss the performance of X ray pulsars navigation by analyzing the transformation error of TOA. In addition, the observability of the system is discussed by Piece Wise Constant System (PWCS) theory, and the system is completely observable in the theoretical analysis. The Extended Kalman Filter (EKF) is used to estimate the states. Simulation results show that the navigation system can provide positions and velocities of lunar satellite with a high accuracy. Thus, it is a suitable scheme for autonomous navigation of lunar satellite.
To solve the spatially varying out of focus deblurring problem of a conventional camera, a spatially varying out of focus deblurring approach based on blur map and L1 2 optimization is proposed. Firstly, the defocusing model of camera is studied and analyzed, and the principle, characteristics and applicability of circular defocusing model and Gaussian defocusing model are presented. And then, the local contrast prior condition is modified using the edge properties, the blur map is obtained in combination with the gradient information of fuzzy edge, and a guided filtering method is adopted to remove the ambiguity around edges and the noise of blur map, thus obtain a better blur map. Finally, L1 2 optimization that combines Tikhonov like regularization and TV regularization is applied to image deburring, which is accomplished with variable splitting and punishment method, and the all in focus image is obtained using scale selection and image reconstruction. The experimental results based on both synthetic image and real image show that the proposed approach outperforms the state of the art space invariant and spatially varying deblurring methods.
Considering that manual adjustment of the light guide plate illumination for civil aircraft cockpit not only increases the pilot's workload, but also has difficulties in precisely controlling the brightness of light guide plate according to cockpit light environment, we studied the self adaptive dimming control technology for the lighting system of light guide plate. Ambient light distribution in different areas was established through cockpit 3D modeling and SPEOS optical simulation, the layout of ambient light sensors was determined, and the brightness dimming curve model was established through ergonomics test for cockpit light environment and statistical analysis of confidence interval. Based on which, an ideal model of self adaptive dimming control for the light guide plate illumination was proposed, which provides a theoretical basis for application of the research result in the field of aircraft design.
Fault data of weapon systems are small sample grey sequencewhich often take on the wobbly characteristic.It is found by research that modeling of the grey wobbly sequence does not satisfy the condition of GM (11) model.Thereforeit is proposed to use the dynamic exponent transformation for transforming the grey wobbly sequence into a monotonically increasing sequence with certain grey exponent lawand then to establish a GM (11) modelwhich is called as grey linear power exponent function curve model (GIM (1)).For GIM (1)the unary linear regression modeling method is used for model parameter identification.The results prove that GIM (1) model has good fitting and prediction accuracy for the grey wobbly sequence of the weapon systems fault sequencewhich not only has the advantage of grey identification algorithmbut also can meet the identification requirement of general system.
Fault data of weapon systems are small sample grey sequence, which often take on the wobbly characteristic. It is found by research that modeling of the grey wobbly sequence does not satisfy the condition of GM (1, 1) model. Therefore, it is proposed to use the dynamic exponent transformation for transforming the grey wobbly sequence into a monotonically increasing sequence with certain grey exponent law, and then to establish a GM (1, 1) model, which is called as grey linear power exponent function curve model (GIM (1)). For GIM (1), the unary linear regression modeling method is used for model parameter identification. The results prove that GIM (1) model has good fitting and prediction accuracy for the grey wobbly sequence of the weapon systems fault sequence, which not only has the advantage of grey identification algorithm, but also can meet the identification requirement of general system.