GUIDANCE AND CONTROL FOR AUTOMATIC LANDING OF UAV

A scheme of guidance and control is presented to meet the requirements for automatic landing of unmanned aerial vehicles (UAVs) based on the airborne digital flight control system and radio tracker on ground station. An automatic landing system is realized for an unmanned aerial vehicle. The results of real time simulation and flight test are given to illustrate the effectiveness and availability of the scheme. Results meet all the requirements for automatic landing of the unmanned aerial vehicle.

Guidance and Control Techniques of Carrier-Based Aircraft for Automatic Carrier Landing

We summarize the guidance and control techniques of automatic carrier landing for carrier-based aircraft.First,we analyze the carrier landing operations of the manned fixed-wing aircraft,unmanned fixed-wing aircraft and helicopters.Second,we look into the navigation and guidance system and the flight control methods for current different aircraft.Finally,we draw several conclusions of the development prospects for aircraft carrier landing,including the precision landing control techniques,precision approach and landing guidance techniques,and adaptive,reconfigurable and intelligent flight control techniques.

Automatic Carrier Landing Control for Unmanned Aerial Vehicles Based on Preview Control

For carrier-based unmanned aerial vehicles(UAVs),one of the important problems is the design of an automatic carrier landing system(ACLS)that would enable the UAVs to accomplish autolanding on the aircraft carrier.However,due to the movements of the flight deck with six degree-of-freedom,the autolanding becomes sophisticated.To solve this problem,an accurate and effective ACLS is developed,which is composed of an optimal preview control based flight control system and a Kalman filter based deck motion predictor.The preview control fuses the future information of the reference glide slope to improve landing precision.The reference glide slope is normally a straight line.However,the deck motion will change the position of the ideal landing point,and tracking the ideal straight glide slope may cause landing failure.Therefore,the predictive deck motion information from the deck motion predictor is used to correct the reference glide slope,which decreases the dispersion around the desired landing point.Finally,simulations are carried out to verify the performance of the designed ACLS based on a nonlinear UAV model.

H_∞ Preview Control for Automatic Carrier Landing

This paper focuses on the application of H_∞preview control in automatic carrier landing system(ACLS)for carrier-based aircraft.Due to the mutual movement between aircraft and carrier,the landing process becomes considerably more challenging compared to a conventional runway landing.ACLS systems mitigate this by predicting deck motion and generating ideal glide slope path for tracking.Although,this predicted glide slope information is available in advance,conventional control structures are still unable to use this future information.H_∞preview control has the ability to utilize this future information for improving tracking response and disturbance rejection.The process of incorporating preview information into ACLS framework and synthesizing the H_∞preview controller is presented.The methodology is verified using the example of F/A-18 automatic carrier landing problem and results are presented.

Hover performance estimation and validation of battery powered vertical takeoff and landing aircraft

Battery powered vertical takeoff and landing(VTOL) aircraft attracts more and more interests from public, while limited hover endurance hinders many prospective applications. Based on the weight models of battery, motor and electronic speed controller, the power consumption model of propeller and the constant power discharge model of battery, an efficient method to estimate the hover endurance of battery powered VTOL aircraft was presented. In order to understand the mechanism of performance improvement, the impacts of propulsion system parameters on hover endurance were analyzed by simulations, including the motor power density, the battery capacity, specific energy and Peukert coefficient. Ground experiment platform was established and validation experiments were carried out, the results of which showed a well agreement with the simulations. The estimation method and the analysis results could be used for optimization design and hover performance evaluation of battery powered VTOL aircraft.

Iterative Model Predictive Control for Automatic Carrier Landing of Carrier-Based Aircrafts Under Complex Surroundings and Constraints

This paper considers the automatic carrier landing problem of carrier-based aircrafts subjected to constraints,deck motion,measurement noises,and unknown disturbances.The iterative model predictive control(MPC)strategy with constraints is proposed for automatic landing control of the aircraft.First,the long short-term memory(LSTM)neural network is used to calculate the adaptive reference trajectories of the aircraft.Then the Sage-Husa adaptive Kalman filter and the disturbance observer are introduced to design the composite compensator.Second,an iterative optimization algorithm is presented to fast solve the receding horizon optimal control problem of MPC based on the Lagrange’s theory.Moreover,some sufficient conditions are derived to guarantee the stability of the landing system in a closed loop with the MPC.Finally,the simulation results of F/A-18A aircraft show that compared with the conventional MPC,the presented MPC strategy improves the computational efficiency by nearly 56%and satisfies the control performance requirements of carrier landing.

Trajectory Tracking of Vertical Take-off and Landing Unmanned Aerial Vehicles Based on Disturbance Rejection Control

We investigate the trajectory tracking problem of vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV), and propose a practical disturbance rejection control strategy. Firstly, the nonlinear error model is established completely by the modified Rodrigues parameters, while considering dynamics of the servo actuators. Then, a hierarchical control scheme is applied to design the translational and rotational controllers based on the time-scale property of each subsystem, respectively. And the linear extended state observer and auxiliary observer are used to deal with the uncertainties and saturation. At last, global stability of the closed-loop system is analyzed based on the singular perturbation theory. Simulation results show the effectiveness of the proposed control strategy. © 2014 Chinese Association of Automation.

Autonomous Landing of Small Unmanned Aerial Rotorcraft Based on Monocular Vision in GPS-denied Area

Focusing on the low-precision attitude of a current small unmanned aerial rotorcraft at the landing stage, the present paper proposes a new attitude control method for the GPS-denied scenario based on the monocular vision. Primarily, a robust landmark detection technique is developed which leverages the well-documented merits of supporting vector machines (SVMs) to enable landmark detection. Then an algorithm of nonlinear optimization based on Newton iteration method for the attitude and position of camera is put forward to reduce the projection error and get an optimized solution. By introducing the wavelet analysis into the adaptive Kalman filter, the high frequency noise of vision is filtered out successfully. At last, automatic landing tests are performed to verify the method's feasibility and effectiveness. © 2014 Chinese Association of Automation.

Selection of a non-localized landing region for an unmanned helicopter based on an attention model

A new landing region selection algorithm for an unmanned helicopter is proposed based on an attention model.Different from the original attention model,some properties of the possible safe landing regions（e.g.,depth,regional color and motion features）are included in the selection algorithm.Furthermore,regional color and motion features are fused directly into the saliency map because these features do not have the ＂central-peripheral＂property.Experimental results validate the feasibility and efficiency of this approach.

MC-LRF based pose measurement system for shipborne aircraft automatic landing

Due to the portability and anti-interference ability,vision-based shipborne aircraft automatic landing systems have attracted the attention of researchers.In this paper,a Monocular Camera and Laser Range Finder(MC-LRF)-based pose measurement system is designed for shipborne aircraft automatic landing.First,the system represents the target ship using a set of sparse landmarks,and a two-stage model is adopted to detect landmarks on the target ship.The rough 6D pose is measured by solving a Perspective-n-Point problem.Then,once the rough pose is measured,a region-based pose refinement is used to continuously track the 6D pose in the subsequent image sequences.To address the low accuracy of monocular pose measurement in the depth direction,the designed system adopts a laser range finder to obtain an accurate range value.The measured rough pose is iteratively optimized using the accurate range measurement.Experimental results on synthetic and real images show that the system achieves robust and precise pose measurement of the target ship during automatic landing.The measurement means error is within 0.4in rotation,and 0.2%in translation,meeting the requirements for automatic fixed-wing aircraft landing.

基于Landsat8影像的土地利用覆盖监督分类方法对比研究

以Landsat 8遥感影像为数据源,通过对比最小距离、马氏距离和最大似然这3种分类器的分类精度,对研究区的土地利用覆盖分类方法进行研究,最大似然分类器的分类结果优于最小距离和马氏距离,总体精度为70.59%,Kappa系数为0.6187,所得分类精度较高。该研究方法可用于快速获取地区的土地利用覆盖分类,具有一定的现实意义。

Application of Feedback Linearization Method in Airplane Auto-matic Landing Control System

Summarizes the I/O feedback linearization about MIMO system, and applies it to nonlinear control equation of airplane. And also designs the tracing control laws for airplane longitudinal automatic landing control system.

多情景下中型航空公司碳排放预测研究

在国际国内减碳的大背景下,文章选择国内某中型航空公司作为研究对象,首先利用ICAO碳排放计算法,依据航班进程的两个阶段(LTO和CCD阶段),对2015—2019年的碳排放量状况进行计算分析,再通过设置不减碳情景、基础减碳情景、快速减碳情景和理想减碳情景4个民航发展情景,使用基于Python语言的蒙特卡洛模拟方法,以2021年为基准,对该航空公司2022—2035年内的碳排放进行仿真预测。结果表明:由于中型航空公司的发展需求,4种情况下都无法完成碳排放总量达峰,但其每万架次碳排放量明显降低,表明碳减排措施的有效性。最后从国内外理论研究和现实应用的角度出发,为中型航空公司提出了多条低碳发展建议,以助力我国民航业早日实现碳达峰、碳中和的重要目标。

垂直起降系统的互补滑模与情感神经网络控制

针对具有未知扰动的垂直起降机双闭环控制系统,提出一种基于连续径向基情感神经网络的互补积分滑模控制策略。建立了包含未知扰动项的垂直起降机的数学模型,为系统内外环分别设计滑模控制器和互补积分滑模控制器,基于对系统鲁棒性的考量,利用连续径向基情感神经网络逼近系统未知扰动项,给出神经网络权重的自适应律,形成一套新型的复合控制策略,利用Lyapunov方法分析了系统的稳定性。通过对垂直起降机的仿真实验与实物实验进行分析对比,证明了所设计的控制器具有更快的收敛速度、更高的跟踪精度和更佳的鲁棒性。

全自动精密进近引导与传输技术研究

全自动着舰是保障舰载机着舰安全性和提高出动率的关键手段,分析了外军舰载机全自动着舰引导及传输系统发展及应用情况,研究了海上母舰动基座、复杂电磁环境下的应用需求,突破了抗干扰条件下的卫导高精度测量、动基准差分卫导相对定位、低时延高可靠传输等相关技术,提出了基于差分卫导与新体制着舰数据链相结合的全自动精密进近引导与传输系统综合解决方案。通过原型系统研制和典型环境下的测试验证,证明了原理的可行性,技术指标在双动状态下相对定位精度达分米级,传输时延达毫米级,与国外技术水平相当,可为无人机起降着陆及舰载机自动着舰相关装备研制提供重要参考。

不同海况条件下舰载无人机着舰安全分析

针对无人机上舰的使用需求,本文对舰载无人机着舰开展了系统的研究。建立了机-舰-环境综合模型和舰载无人机全自动着舰引导控制系统;基于建立的舰载无人机着舰综合模型对不同海况下的着舰过程进行仿真分析,研究不同海况条件以及航母不同航速和遭遇角对着舰安全的影响。仿真研究表明:在复杂海况下,航母可通过适当提高航速以获得更高的着舰成功率,但过高的航速会导致舰尾流扰动加剧,使得着舰成功率显著下降;通过对仿真结果进行统计分析,给出了不同海况下的着舰安全范围,为无人机着舰辅助决策提供参考。

航母舰载无人机全自动着舰技术特点分析

全自动着舰技术是无人机上舰必须解决的“使能”技术。2013年,美军已完成X-47B无人机验证机在航母上的全自动着舰试验验证,为其发展MQ-25A“黄貂鱼”航母舰载无人机装备奠定了良好的技术基础。在梳理飞机着陆与着舰差异的基础上,给出航母舰载无人机全自动着舰的通用流程;从地位作用、工作范围、系统构架、系统要求、实现手段以及关键技术支撑等角度,对比有人机重点分析了航母舰载无人机全自动着舰的特点,为后续关键技术研究和武器装备建设发展提供参考。

基于改进YOLOv8的飞机起降飞行姿态风险检测

飞机在执行飞行任务时,其起飞和降落两个阶段是整个飞行过程中最关键和最具挑战性的时刻之一,其起降飞行姿态的变化程度关系到整个飞机的安全性。为了降低飞机在起降过程的风险性,提出了一种基于改进YOLOv8的飞机起降飞行姿态的风险检测方法。该检测方法综合利用了CBAM注意力机制、GSConv轻量化卷积模块和HIOU准则函数等深度学习和目标检测技术,实现了对飞机机翼、起落架等关键结构部位的准确检测,以便利用识别到的飞行姿态特征参数来对飞机当前的安全状态进行分析和评估。经实验验证表明,该改进方法对于飞机起降阶段中的飞行姿态风险状况能够进行精准识别和检测,具有较高的可靠性。

基于安全性的电动垂直起降飞行器飞控系统架构设计

飞行控制系统作为电动垂直起降(electric vertical take-off and landing,eVTOL)飞行器的关键机载系统,需要具备和民机同样的安全性。为了设计满足eVTOL飞行器需求的飞控系统架构,根据适航规章梳理了安全性要求,并基于安全性要求介绍了eVTOL飞行器飞控系统飞控计算机、传感器和作动器余度设计技术,设计了一种基于安全性考虑的eVTOL飞行器飞控系统架构;分析了eVTOL飞行器旋翼构型下的典型功能危险,并采用故障树进行了安全性分析。结果表明,设计的飞控系统架构的典型功能危险能够满足失效概率的要求。

基于仿生技术的尾座式VTOL无人机起降稳定控制及轨迹优化

尾座式垂直起降(Vertical takeoff/landing,VTOL)无人机(Unmanned aerial vehicle,UAV)稳定性差,与传统起落架的适配性低。针对上述问题,提出了一种采用自由尾翼技术的新型起落架。该起落架采用串联多级结构,在降低机身高度的同时,保证了巡航状态下尾翼力臂的长度,并通过虚拟中心点力分布技术对动态着陆过程进行调控,简化了控制过程,有利于模式转换过程中的无缝轨迹优化。随后基于猫中心点单点数据集,利用神经网络对起落架控制进行训练,有效提高了起落架自适应起落速度和精度。最后,结合无人机不同模式的参数要求,进行多目标优化和相似性转换,有效提高了尾座式垂直起降无人机的着陆适应性和稳定性。