Two-layer formation-containment fault-tolerant control of fixed-wing UAV swarm for dynamic target tracking

This paper tackles the formation-containment control problem of fixed-wing unmanned aerial vehicle(UAV)swarm with model uncertainties for dynamic target tracking in three-dimensional space in the faulty case of UAVs’actuator and sensor.The fixed-wing UAV swarm under consideration is organized as a“multi-leader-multi-follower”structure,in which only several leaders can obtain the dynamic target information while others only receive the neighbors’information through the communication network.To simultaneously realize the formation,containment,and dynamic target tracking,a two-layer control framework is adopted to decouple the problem into two subproblems:reference trajectory generation and trajectory tracking.In the upper layer,a distributed finite-time estimator(DFTE)is proposed to generate each UAV’s reference trajectory in accordance with the control objective.Subsequently,a distributed composite robust fault-tolerant trajectory tracking controller is developed in the lower layer,where a novel adaptive extended super-twisting(AESTW)algorithm with a finite-time extended state observer(FTESO)is involved in solving the robust trajectory tracking control problem under model uncertainties,actuator,and sensor faults.The proposed controller simultaneously guarantees rapidness and enhances the system’s robustness with fewer chattering effects.Finally,corresponding simulations are carried out to demonstrate the effectiveness and competitiveness of the proposed two-layer fault-tolerant cooperative control scheme.

Radio Controlled “3D Aerobatic Airplanes” as Basis for Fixed-Wing UAVs with VTOL Capability

There are fundamental performance compromises between rotary-wing and fixed-wing UAVs. The general solution to address this well-known problem is the design of a platform with some degree of reconfigurable airframes. For critical missions (civilian or military), it is imperative that mechanical complexity is kept to a minimum to help achieve mission success. This work proposes that the tried-and-true radio controlled (RC) aerobatic airplanes can be implemented as basis for fixed-wing UAVs having both speed and vertical takeoff and landing (VTOL) capabilities. These powerful and highly maneuverable airplanes have non-rotatable nacelles, yet capable of deep stall maneuvers. The power requirements for VTOL and level flight of an aerobatic RC airplane are evaluated and they are compared to those of a RC helicopter of similar flying weight. This work provides quantitative validation that commercially available RC aerobatic airplanes can serve as platform to build VTOL capable fixed-wing UAVs that are agile, cost effective, reliable and easy maintenance.

A Software-in-the-Loop Implementation of Adaptive Formation Control for Fixed-Wing UAVs

This paper discusses the design and software-in-theloop implementation of adaptive formation controllers for fixedwing unmanned aerial vehicles(UAVs) with parametric uncertainty in their structure, namely uncertain mass and inertia. In fact, when aiming at autonomous flight, such parameters cannot assumed to be known as they might vary during the mission(e.g.depending on the payload). Modeling and autopilot design for such autonomous fixed-wing UAVs are presented. The modeling is implemented in Matlab, while the autopilot is based on ArduPilot, a popular open-source autopilot suite. Specifically, the ArduP ilot functionalities are emulated in Matlab according to the Ardupilot documentation and code, which allows us to perform software-in-the-loop simulations of teams of UAVs embedded with actual autopilot protocols. An overview of realtime path planning, trajectory tracking and formation control resulting from the proposed platform is given. The software-inthe-loop simulations show the capability of achieving different UAV formations while handling uncertain mass and inertia.

Path planning for moving target tracking by fixed-wing UAV

For the automatic tracking of unknown moving targets on the ground,most of the commonly used methods involve circling above the target.With such a tracking mode,there is a moving laser spot on the target,which will bring trouble for cooperative manned helicopters.In this paper,we propose a new way of tracking,where an unmanned aerial vehicle(UAV) circles on one side of the tracked target.A circular path algorithm is developed for monitoring the relative position between the UAV and the target considering the real-time range and the bearing angle.This can determine the center of the new circular path if the predicted range between the UAV and the target does not meet the monitoring requirements.A transition path algorithm is presented for planning the transition path between circular paths that constrain the turning radius of the UAV.The transition path algorithm can generate waypoints that meet the flight ability.In this paper,we analyze the entire method and detail the scope of applications.We formulate an observation angle as an evaluation index.A series of simulations and evaluation index comparisons verify the effectiveness of the proposed algorithms.

VTOL UAVs for Forest Monitoring and Management via Remote Sensing: A Case Study in Khao Yai National Park, Thailand

The utilization of UAVs (Unmanned Aerial Vehicles) has experienced a remarkable upsurge in various industries, including forestry. Their capacity to expeditiously and effectively cover large tracts of land has resulted in their widespread adoption as a valuable forest management and monitoring tool. The versatility of UAVs extends to their capability to perform quick and efficient surveys of large areas, inventory of tree species, and monitoring of forest health. This research paper reports on the successful utilization of VTOL (Vertical Takeoff and Landing) UAV that was designed and built at the IESSD (Institute of Earth Science and Sustainable Development) located in the AAA (Asia Aviation Academy) at KMITL (King Mongkut’s Institute of Technology Ladkrabang) Prince of Chumphon Campus, Thailand. The VTOL UAV is employed for resource and environmental missions, as well as forest monitoring by using remote sensing technology. VTOL UAVs are used for aerial surveillance to conduct air photography, data collection, and processing for resource and environmental missions. This research paper presents a comprehensive analysis of the areas at risk of deforestation and forest encroachment in a particular region of Khao Yai National Park in Thailand, highlighting the potential for the resulting photographs to inform evidence-based decision-making and facilitate sustainable forest management practices. This study offers recommendations to develop VTOL UAVs remote sensing capabilities and mitigate deforestation and forest encroachment in Khao Yai National Park.

Retarded Harrier Maneuver as a New and Efficient Approach for Fixed-Wing Aircraft to Achieve S/VTOL

Modern day VTOL fixed-wing aircraft based on quadplane design is relatively simple and reliable due to lack of complex mechanical components compared to tilt-wings or tilt-rotors in the pre-80’s era. Radio-controlled aerobatic airplanes have thrust-to-weight ratio of greater than unity and are capable of performing a range of impressive maneuvers including the so-called harrier maneuver. We hereby present a new maneuver known as the retarded harrier that is applicable to un/manned fixed-wing aircraft for achieving VTOL flight with a better forward flight performance than a quadplane in terms of weight, speed and esthetics. An airplane with tandem roto-stabilizers is also presented as an efficient airframe to achieve VTOL via retarded harrier maneuver, and detailed analysis is given for hovering at 45° and 60° and comparison is made against the widely adopted quadplane. This work also includes experimental demonstration of retarded harrier maneuver using a small remotely pilot airplane of wingspan 650 mm.

Technical Analysis of VTOL UAV

Overall, this paper explains the related information about VTOL and trend of this technology worldwide. Also, it comes up with the distinction among VTOL and helicopter and fixed wing aircraft. This paper concentrates on domestic and international drones that utilize VTOL technology. Also, this paper gives the explanation about VTOL’s performance and object. Furthermore, this paper predicts the future of VTOL and which area this technology going to be used.

Analysis of VTOL UAV Propellant Technology

Recently, the surge in the interests in unmanned aerial vehicles has soared dra-matically worldwide due to many potential benefits foreseen by this technology. The most widespread use of the commercial drones is a multi-copter form of unmanned aerial vehicle, because of its vertical takeoff and landing (VTOL) capability. However, due to the structural characteristics, it has a disadvantage that the flight time is quite short, which is typically ranging between 15 to 30 minutes. The fixed wing type of unmanned aerial vehicles has a longer flight time and duration, but it is not easy to secure a safe landing space, especially in the city areas. For this reason, demand for vertical fixed take-off and landing aircraft is rapidly increasing throughout the world. This study analyzes the trends and recent development of global VTOL technology and provides a direction into which the current state of the technology should be heading. By comparing the advantage and disadvantage of various VTOP propulsion types, we can clearly identify the most effective form of VTOL propulsion types. Such analysis will be highly beneficial to the drone researchers and scientists in terms of future development.

Development of Autonomous VTOL UAV for Wide Area Surveillance

The drone was developed with the use of unmanned aircraft systems in the initial military sector based on the combination of aerospace technology and information and communication technologies in a variety of usability, including the civilian sectors. Developed for the field of reconnaissance, it is used in both civilian and police sectors as traffic monitoring and high altitude reconnaissance missions. It is used in broadcasting and surveillance, while continuously expanding into the areas of courier delivery and rescue missions. Based on the convergence of aviation technology such as various SW, sensor and flight control to utilize unmanned system and information communication technology, commercialization of related technology is being developed as a very diverse route.?In this paper, we propose and manufacture of?a VTOL UAV. Design process referred to the VTOL development process?that has been devised by us, and actual building of a UAV also applied the same VTOL development concept. In order to understand the aerodynamic characteristics of the aircraft, we have applied the aerodynamic design theory and used the CAE method that can replace the actual wind tunnel test. We tested the selection method and criteria for the internal modules that make up the UAV, and we were able to assemble the product. FW coding of flight control computer was conducted for VTOL control. In addition, we developed a LTE communication module for the long distance flight, and carried out flight experiments with GCS to observe and respond to the flight situation from the ground. Flight test results showed that stable transition flight was possible with broadband.?We could see that the actual performance results were met, compared to our development target values.

改进的TECS在VTOL倾转翼无人机中的应用

以垂直起降(VTOL)倾转翼无人机为研究对象,优化了总能量控制系统(TECS)的核心算法,实现了固定翼模式下的大包线纵向解耦控制,同时设计了垂向速度限幅调节策略和失速保护策略,提高了无人机的飞行安全,降低了工程应用中参数适配的复杂性。经过仿真验证、平原试飞和高原试飞验证,解决了高度控制和速度控制的超调,高度轨迹跟踪误差减小了19.9%,垂向速度限幅调节策略有效。失速保护策略只进行仿真测试,通过强突风干扰诱发失速保护,无人机迅速增大空速,保证了飞行安全。

基于CFD方法的垂直起降飞行器气动设计与分析

设计了一种复合式动力布局的垂直起降(vertical takeoff and landing, VTOL)飞行器,该飞行器采用无尾三角翼气动布局,静稳定设计,在其处于固定翼模式的情况下,使用CFD方法,基于Standard k-ε湍流模型对其进行了仿真分析。获得了在一定范围的迎角下飞行器的气动参数曲线以及升阻力情况,为该飞行器结构设计及控制系统设计提供了依据。仿真结果表明,该飞行器具有较小的阻力系数,且在最大升阻比附近的动态范围较宽,尤其适合高速飞行的场合。俯仰力矩几乎为0,无需平尾配平俯仰力矩,降低了控制系统的设计难度。飞行器整体设计布局合理,气动效率较高。

复合翼无人机混合动力系统能量管理策略设计

以某最大起飞质量为25 kg的复合翼无人机混合动力系统为研究对象,基于MATLAB/Simulink平台搭建动力系统关键部件数学模型、集成复合翼无人机混合动力系统级仿真模型,依据复合翼无人机在多点悬停作业场景下的飞行任务要求,设计相应的飞行任务剖面与基于等效燃油最小消耗的能量管理策略,进行仿真试验验证。结果表明:基于等效燃油最小消耗能量管理策略的无人机动力系统的油门跟随性良好,满足无人机实际运行需要;动力电池荷电状态可以维持在设定值附近,相对误差小于1.5%;相比基于规则的能量管理策略,基于等效燃油最小消耗管理策略的混合动力系统无人机在点对点飞行和多点悬停作业2种飞行工况下的燃油消耗分别下降了6.07%、5.49%。

高效多模式混合推进垂起无人机动力系统研究

针对现有商用工业级垂起无人机在面向新一代无人业务时的长垂直机动时间的研制需求,设计了一种起飞重量约20kg级的垂起无人机高效多模式混合推进动力系统,该系统以发动机、太阳能以及锂电池作为动力源,详细介绍了动力系统的开发方法及软件测控方式,通过一体化验证试验方法对动力系统进行了地面台架及试飞平台验证。试验结果表明,设计的动力系统能够满足中型商用垂起无人机功率及任务需求,能够提升传统垂起无人机垂直机动时间,具有较好的应用前景。

垂直起降无人机自主视觉着舰方法

考虑垂直起降无人机着舰问题的特殊性,提出了一种基于机载视觉的自主着舰方案。突破了传统2D光流测速的弊端,利用图像球面光流估计出目标舰船的三维速度矢量。为解决传统位置控制方案对着落轨迹精度控制不足的问题,利用Tau理论实时规划出一条满足着舰软着落约束条件的期望轨迹,最终以无人机三维飞行速度矢量作为控制量设计了轨迹跟踪控制器。基于Unity3D软件开发视景仿真环境,模拟不同海况条件,对所设计系统进行了半实物闭环仿真验证。与传统轨迹规划方案相比,所提方法无需复杂优化迭代计算,能同时满足着舰的实时性和精确性需求。

复合翼垂直起降无人机直驱混合动力系统验证设计与试验建模方法

针对传统复合翼垂直起降(vertical take-off and landing,VTOL)无人机(unmanned aerial vehicle,UAV)垂直机动时间短的固有缺陷,提出了一种应用油电混动技术的直驱混合动力系统拓扑结构。面向起飞质量约15~20 kg的复合翼垂直起降无人机对直驱混合动力系统的软硬件进行开发与选型,设计出了满足上述起飞质量下功率需求的直驱混合动力系统。为对动力系统的设计方法进行验证并在探究其特性规律的基础上建立简化的直驱混合动力系统数学仿真模型,搭建了能够在地面模拟搭载直驱混合动力的复合翼垂起无人机飞行工况与工作模式的直驱混合动力系统地面一体化验证平台。基于此验证平台,设计了直驱混合动力系统特性一体化探究试验方案,采用试验建模法建立了简化的直驱混合动力系统的稳态与动态数学仿真模型,通过仿真与实物对比试验分析法,验证了试验方案的可行性与模型准确性。直驱混合动力系统配装复合翼垂直起降无人机搭建飞行验证平台并完成垂直机动飞行试验,试验过程中,全系统工作正常,飞行验证平台垂直机动时间超过预期指标。飞行试验结果表明,直驱混合动力系统设计方法是正确且有效的,动力系统具有良好的功率输出表现,能够改善复合翼垂起无人机垂直机动时间短的固有缺陷。

Prediction of electric-powered fixed-wing UAV endurance

To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery discharge characteristics under different operating conditions,the required battery power model and battery discharge model were studied.The required battery power model was determined using an approximate model of electric power system efficiency based on wind tunnel testing and the self-adaptive penalty function.Furthermore,current correction and ambient temperature correction terms were proposed for the trained Kriging model representing the discharge characteristics under standard operation,and then the discharged capacity-terminal voltage model was established.Through numerical integration of this model with the required battery power model,the electric-powered fixed-wing UAV endurance prediction model was obtained.Laboratory tests indicated that the proposed endurance model could precisely calculate the battery discharge time and accurately describe the battery discharge process.The similarity of the theoretical and flight test results reflected the accuracy of the proposed endurance model as well as the importance of considering dynamic changes in power system efficiency in endurance calculations.The proposed endurance model meeting precision requirements can be used in practical engineering applications.

垂直起降固定翼无人机混合电推进系统设计与仿真研究

垂直起降固定翼无人机综合了固定翼和多旋翼的优势,在未来航空工业拥有良好前景,针对其动力系统结构分布和动力需求的特点,提出增程式油电混合电推进系统方案,根据飞行动力学和功率需求,对动力系统的各部件进行参数匹配与选型,结合恒功率控制策略建立油电混合电推进系统模型进行仿真分析。结果表明:电池SOC值最终稳定在0.35~0.45范围内,旋翼电机和尾桨电机均运转在参数匹配结果范围内,该混合电推进系统方案设计和参数匹配具有合理性。

一种基于任务空间的T-VTOL多模态轨迹生成算法

针对尾座式垂直起降无人机(T-VTOL)多模态轨迹规划复杂的问题,提出了一种面向任务空间的多模态轨迹生成算法。证明了T-VTOL全模态的微分平坦特性,位置的高阶导数是系统平坦的输出,表明T-VTOL可以在任务空间内设置符合期望轨迹的任意定点。基于庞特里亚金极小值原理提出了T-VTOL在三维空间的多模态轨迹生成算法与封闭解,并给出其可行性验证方法。结果表明,在两种过渡模态以及盘旋模态,T-VTOL飞行轨迹严格遵循任务空间约束。此外,所提算法具有计算时间短,算力要求低,易于部署的优点。

尾坐式超小型定翼机飞行运动建模与仿真

尾坐式超小型无人定翼机结构简单、飞行效率高、实用性强,其特有的飞行模式与传统飞行器显著不同,分析并掌握其运动特性具有重要意义。提出了一种尾坐式无人定翼机的新方案。为获得其基本气动参数,利用FLUENT进行CFD仿真建立其空气动力学数据库。为分析其各种运动模式,采用四元素法描述其运动姿态,并建立其六自由度飞行运动模型。最后,基于SIMULINK/Aerospace建立运动仿真平台,仿真结果表明该方案垂直起降过程的可行性,为后续控制系统设计与导航奠定了基础。

非定常气动力对垂起固定翼无人机动力学的影响

由于垂起固定翼无人机结构复杂,无论是采用数值模拟得到其非定常气动力还是采用单刚体建模方法建立其动力学模型都较为困难。为了解决该问题,通过CFD数值模拟机翼翼型的迟滞环线,引入无人机俯仰运动所产生的迟滞效应,通过ONERA方程建立无人机垂起改平飞过程的非定常气动力模型,最终基于多体动力学,将无人机划分成机翼、机身、旋翼、舵面的多刚体系统,通过凯恩方程推导并建立无人机动力学模型,通过数值仿真可以发现:多体动力学的方法适用于这类结构复杂无人机的建模,引入机翼的迟滞环对无人机的俯仰运动起阻尼作用;引入非定常气动力与未引入非定常气动力相比垂起速度存在8%的差异,垂起改平飞过程结束时两者上升速度存在40%的差异。