Airborne Optoelectronic Platform Research Articles

Research on Servo Control Algorithm of Photoelectric Stabilized Platform Based on Sliding Mode Active Disturbance Rejection

Aiming at the problems of parameters to be modified and the indistinct physical meaning of the photoelectric stabilization platform control based on the principle of active disturbance rejection, a sliding mode active disturbance rejection control algorithm is proposed. The mathematical model of the control system of the two-axis optoelectronic stabilization platform is established. The external disturbance and various order states of the airborne optoelectronic stabilization platform are estimated in actual time by using the extended state observer, and the optimal control function is constructed by the sliding mode reaching law to complete the nonlinear reactive reactance. The optimization of the disturbance controller structure is carried out, and the algorithm is verified by Matlab simulation. The simulation results show that after the photoelectric stabilization platform adopts the sliding mode ADRC controller, it not only retains the advantages of strong nonlinear ADRC resistance to load disturbance, but also can effectively suppress the external disturbance and realize the high-precision position of the photoelectric stabilization platform control.

New-type gimbal mount of airborne optoelectronic platform and its key technologies

介绍了国外新型机载光电平台万向架及其涉及的关键技术。结合机载光电系统装备产品发展趋势，叙述了机载光电系统万向架平台技术现状，从万向架平台配置、隔振形式以及稳定精度等方面做了介绍；从任务集成、高精度稳定以及运动补偿等方面分析了机载光电系统对万向架平台提出的更大任务传感器布局空间、更强的运动补偿功能以及更高的环架稳定性能等要求；研究了国外新型的无约束驱动-主动随动和并联式-主动随动机载光电万向架平台创新技术，结果表明，国外新型机载光电平台万向架在任务负载/万向架质量比大于1的基础上，实现了3轴优于5 μrad的稳定性能；最后提出了新型机载光电万向架平台关键支撑技术。

Systematic Error Correction for Geo-Location of Airborne Optoelectronic Platforms

In order to improve the geo-location accuracy of the airborne optoelectronic platform and eliminate the influence of assembly systematic error on the accuracy, a systematic geo-location error correction method is proposed. First, based on the kinematic characteristics of the airborne optoelectronic platform, the geo-location model was established. Then, the error items that affect the geo-location accuracy were analyzed. The installation error between the platform and the POS was considered, and the installation error of platform’s pitch and azimuth was introduced. After ignoring higher-order infinitesimals, the least square form of systematic error is obtained. Therefore, the systematic error can be obtained through a series of measurements. Both Monte Carlo simulation analysis and in-flight experiment results show that this method can effectively obtain the systematic error. Through correction, the root-mean-square value of the geo-location error have reduced from 45.65 m to 12.62 m, and the mean error from 16.60 m to 1.24 m. This method can be widely used in systematic error correction of relevant photoelectric equipment.

Multitarget location capable of adapting to complex geomorphic environment for the airborne photoelectric reconnaissance system

In order to achieve accurate locations of multiple targets on an airborne optoelectronic platform, we propose a multitarget location system based on the digital elevation model and a multitarget location model based on the target vector. Through the target detection algorithm, the pixel coordinates of each target in the field of view can be obtained and the visual axis vector of each target is constructed. By integrating the measurement data of each sensor in an unmanned aerial vehicle and the photoelectric platform, the geographical location information of each target can be calculated. In the condition of a flight height of 3000 m, the location error for the main target is 16.47 m, and the location error for the secondary target is about 27.36 m. The effect of the improved filtering model is analyzed. After filtering, the main target location error is reduced to 7 m, and the secondary target location error is reduced to 11 m. The proposed method has the advantages of high real-time performance, high location accuracy, and convenient engineering application.

Multi-target geo-location based on airborne optoelectronic platform

Multi-target geo-location based on airborne optoelectronic platform

Accurate Analysis of Target Data and Transmission of Measuring Information Security by Airborne Photoelectric Platform

Unmanned reconnaissance aircraft can acquire data by remote sensing. The photoelectric imaging platform of unmanned aerial vehicle (UAV) is mounted on the UAV, which uses photogrammetry, image processing and other technologies to accurately analyze the target of interest. With the continuous development of technology, people's requirement for target positioning accuracy is increasing. At the same time, the airborne optoelectronic platform meets the characteristics of wireless sensor networks and needs to deploy key management scheme to ensure the security of data transmission. In this study, coordinate transformation method is used to generate a photoelectric imaging target positioning scheme, based on which the factors affecting the accuracy of target data are analyzed. Using the idea of Monte Carlo algorithm and MatLab simulation, the attitude angle of aircraft and the angle error of gyroscope affect the accuracy of target data. In order to improve the security of data transmission, the identity authentication scheme of Elliptic Curve (ECC) is taken as the research object of key management scheme in this study. Considering the limited resources of wireless sensor networks, a combined public key + identity encryption scheme is proposed. In the simulation process, the scheme shows good performance in encryption/decryption overhead, and the length of ciphertext/private key is controllable. This research is helpful for the airborne photoelectric platform to measure the target data better and ensure the security of data transmission.

Target positioning of UAV airborne optoelectronic platform based on nonlinear least squares

The target positioning algorithm of the traditional unmanned aerial vehicle (UAV) airborne optoelectronic platform introduces a large number of angle measurement errors, resulting in low target positioning accuracy. In this paper, a hybrid nonlinear algorithm of least squares and Gauss-Newton is proposed. Firstly, the Gauss-Newton iterative nonlinear target localization algorithm based on laser ranging value is derived. Then the rough solution of linear least square is used as the initial value of the nonlinear Newton iteration method for target location estimation. The algorithm combines the advantages of the simple and easy implementation of the least squares method and the high convergence accuracy of the Gauss-Newton method, and satisfies the requirements of the Gauss-Newton method for the initial value accuracy. Experimental results of measured data show that the longitude error of fixed target positioning results of this method is less than 1.37×10-5 degrees, the latitude error is less than 6.31×10-5 degrees, and the height error is less than 1.78 meters. And the processing time of each positioning is within 6 ms, which meets the requirements of real-time positioning.

Opto-electronic platform tracking control of multi-rotor unmanned aerial vehicles based on composite disturbance compensation

Airborne opto-electronic platforms are very important in unmanned aerial vehicle systems. The stability and tracking performance of airborne opto-electronic platforms are easily affected by disturbance factors, making compensating for those disturbances a very prominent issue. In this paper, compared to the traditional disturbance observer, an improved velocity signal based disturbance observer (IVDOB) is particularly designed to compensate for the disturbance. Then its capability, robustness, and stability are discussed. For improving the stabilization accuracy and tracking performance of airborne opto-electronic platforms, the universal approximation property of fuzzy systems is used to compensate the disturbance further and an adaptive fuzzy control system based on IVDOBs is proposed. To validate the scheme, a series of experiments were carried out. The results show that the proposed control scheme can achieve reliable control precision and satisfy the requirements of airborne opto-electronic platform tasks.

Composite compensation control method for airborne opto-electronic platform mounted on multi-rotor UAV

In order to compensate disturbance and accomplish the stabilized tracking control for airborne platform mounted on multi-rotor unmanned aerial vehicle (MUAV), a self-adjusting tracking control method based on an improved disturbance observer (DOB) and radial basis function (RBF) neural network approximation is proposed. First, a compensated control is introduced into feedback loop in the structure of original disturbance observer, an improved disturbance observer is established based on velocity signals, and the ability of disturbance compensation and robustness are analyzed. Second, aiming at the compensation problem of nonlinear unknown disturbance, a method based on the RBF neural network (RBFNN) approximation properties is utilized. Finally, a composite compensation control structure is designed based on Lyapunov stability theory. The experimental results show that after applying the proposed method, the disturbance of airborne opto-electronic platform is compensated effectively. The proposed method has high precision and stable tracking control performance, and it can fully meet the requirement of airborne opto-electronic platform stability control.

Application of Airborne Electro-Optical Platform with Shock Absorbers

With the rapid development of information technology, the importance of access to information in today's increasingly demanding. And as today's new metal rubber vibration isolation material in the complex conditions of the various characteristics of the advantages make it airborne optoelectronic platform more widely. This article will focus on airborne optical platform shock absorber design, and by the designed shock absorber static and dynamic analysis of its experimental parameters influencing factors and variation of vibration isolation performance of the developed damper. For future airborne optical platform provides experimental basis with the development of shock absorber.

Two-UAV Intersection Localization System Based on the Airborne Optoelectronic Platform

To address the limitation of the existing UAV (unmanned aerial vehicles) photoelectric localization method used for moving objects, this paper proposes an improved two-UAV intersection localization system based on airborne optoelectronic platforms by using the crossed-angle localization method of photoelectric theodolites for reference. This paper introduces the makeup and operating principle of intersection localization system, creates auxiliary coordinate systems, transforms the LOS (line of sight, from the UAV to the target) vectors into homogeneous coordinates, and establishes a two-UAV intersection localization model. In this paper, the influence of the positional relationship between UAVs and the target on localization accuracy has been studied in detail to obtain an ideal measuring position and the optimal localization position where the optimal intersection angle is 72.6318°. The result shows that, given the optimal position, the localization root mean square error (RMS) will be 25.0235 m when the target is 5 km away from UAV baselines. Finally, the influence of modified adaptive Kalman filtering on localization results is analyzed, and an appropriate filtering model is established to reduce the localization RMS error to 15.7983 m. Finally, An outfield experiment was carried out and obtained the optimal results: , , , , where represents the longitude error, represents the latitude error, represents the altitude error, and represents the error radius.

基于机载光电平台的双机交会定位方法

基于机载光电平台的双机交会定位方法

机载光电平台相对角位移测量系统设计

机载光电平台相对角位移测量系统设计

Multi-functional SiC/Al Composites for Aerospace Applications

Multi-functional Al-matrix composites with high volume fraction (55%-57%) of SiC particles are produced with the new pres-sureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopi-cally homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density (2.94 g/cm3), high elastic modulus (220 GPa), prominent thermal management function as a result of low coefficient of thermal expansion (8×10−6 K−1) and high thermal conductivity (235 W/(m·K)) as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.