四旋翼无人机控制系统仿真设计

四旋翼无人机是一种性能优越的垂直起降无人飞行器,能够实现悬停、低速飞行、垂直起降等功能,在军事和民用方面具有重要价值。针对四旋翼无人机的控制系统设计问题,首先分析介绍了四旋翼无人机飞行原理,对其建立动力学模型和运动学模型,然后进行了基于PID控制的控制系统设计,控制系统采用四通道、多闭环的控制结构,包括无人机的姿态控制与轨迹控制。在MATLAB中进行无人机控制系统仿真实现。仿真结果表明,本文所设计的控制系统,能够有效地实现四旋翼无人机的姿态控制、轨迹控制,具有良好的控制精度与响应速度。     

基于虚拟现实的四旋翼无人机控制仿真教学平台

针对现有仿真教学平台在开展对四旋翼无人机控制仿真教学时存在的问题,引入虚拟现实技术开展对四旋翼无人机控制仿真教学平台的设计研究。首先,利用MATLAB和Java设计四旋翼无人机控制仿真教学平台结构框架;其次,对平台中所需的无人机、蓝牙、通信芯片等硬件选型;最后,利用虚拟现实技术构建四旋翼无人机控制模型。通过对比实验证明,新的仿真教学平台可以实现对无人机控制飞行轨迹的直观展示,对于提高仿真教学质量具有重要的意义。     

基于跟踪微分器的四旋翼飞行器控制器

研究小型四旋翼飞行器导航控制优化问题.针对当前许多控制方法需要四旋翼飞行器速度信号,四旋翼无人机无法获取速度信号情况下,传统控制方法便会失效,为解决上述问题,提出采用跟踪微分器的输出反馈控制器.跟踪微分器估算出四旋翼飞行器的速度值,实现无法获取速度信号下的位置和姿态控制,并对基于微分跟踪器的控制器进行了设计和仿真.仿真结果表明上述控制方法和跟踪微分器观测的速度信号的有效性和可行性.     

具有输入死区与扰动的四旋翼无人机自抗扰控制

研究了具有输入死区与扰动的四旋翼无人机的姿态控制问题。由于输入死区普遍存在于四旋翼无人机的执行机构,并且易受到扰动的影响。针对具有输入死区与扰动的四旋翼无人机系统,设计基于自抗扰的动态面控制器。采用自抗扰控制算法设计扩张状态观测器估计系统的总扰动,采用动态面方法设计控制律。所设计的控制器使四旋翼无人机实现对期望姿态角跟踪。仿真结果验证了该方案的有效性。     

基于RFID技术的四旋翼无人机轨迹跟踪控制系统设计

为促进四旋翼无人机的飞行自主性,增强无人监管情况下飞行器主机所具备的避障行进能力,设计基于RFID技术的四旋翼无人机轨迹跟踪控制系统;采用RFID标签识别技术,调制处理既定控制信号,利用标签识别协议,连接微型四旋翼轨迹控制器与内环姿态控制器,通过数据通信链路,提取轨迹跟踪控制所需的传输电子量,完成轨迹跟踪控制系统硬件设计;利用动力系统中的参数辨识策略,确定与轨迹姿态控制相关的物理规律标注,实现四旋翼无人机轨迹跟踪控制;实验结果表明,与机器视觉型控制系统相比,基于RFID技术的控制系统的SSI避障行进指标数值相对较高,全局最大值达到了 79％,四旋翼无人机滚转角平均值为85°,能够有效抑制四旋翼无人机滚转角的数值上升趋势,增强无人监管情况下飞行器主机避障行进能力.     

输入饱和与姿态受限的四旋翼无人机反步姿态控制

本文针对四旋翼无人机研究了鲁棒反步姿态控制策略.由于四旋翼无人机结构复杂,其非线性数学模型难以精确建立,因此在控制器设计过程中需要综合考虑模型不确定性、未知外部干扰、输入饱和以及姿态受限等因素.针对模型中的不确定项,使用神经网络进行逼近;对于外部未知干扰,使用非线性干扰观测器进行补偿;使用双曲正切函数逼近饱和函数,解决输入饱和问题;同时使用界限Lyapunov函数设计控制器,确保姿态满足限制条件.最后,设计四旋翼无人机反步姿态控制器,并根据Lyapunov稳定性定理证明了闭环控制系统的有界稳定.仿真结果表明了所研究控制方法的有效性.     

四旋翼无人机PDF控制系统设计和抗干扰分析

针对传统的PID控制方法在对四旋翼无人机进行控制时动态响应差,抗干扰能力低等局限性,不能够满足高精度要求的四旋翼无人机应用场合的问题。本文以四旋翼无人机的姿态控制为研究对象,通过采用基于伪微分反馈(PDF)控制策略来设计其飞行控制器,以提高动态响应性能和抗干扰能力。在对四旋翼无人机数学建模的基础上,将PDF控制策略引入到四旋翼姿态控制中,提出基于四旋翼无人机对象的PDF控制设计方法,并分别完成PID、PDF控制器的设计和动态仿真。通过对仿真结果比较、分析表明PDF控制与PID姿态控制器相比,系统超调量小,具有更好的鲁棒性和抗干扰能力。     

四旋翼无人机轨迹跟踪的容错控制

针对四旋翼无人机轨迹跟踪的容错控制问题,提出了一个鲁棒[H∞]控制和干扰观测器与故障估计器相结合的容错复合控制器的方法。在外部有界扰动和加性故障的条件下,实现对四旋翼无人机的轨迹跟踪。将四旋翼无人机非线性动态模型解耦成独立的外环位置控制系统和内环角度控制系统,引入区间矩阵对系统参数进行描述,使用干扰观测器和故障估计器进行干扰和故障的估计和补偿。然后设计一个复合控制器既能更好地抑制干扰又能保证无人机在自身存在故障的情况下平稳飞行。通过仿真证明该方法的有效性。     

基于模型的四旋翼无人机半实物仿真平台研究

为了降低在真实飞行器上测试新的控制策略时所存在的设备损坏风险,对四旋翼无人机的控制器和半实物仿真实验平台进行了开发和介绍;首先,分析了四旋翼无人机基本结构和飞行原理,并对其进行了动力学建模;其次,设计了对应的常规PID控制器和滑模控制器,并进行了Matlab仿真对比和分析;最后,展示了采用先进的基于模型的设计方法和代码自动等技术的半实物仿真实验平台,并详细介绍了其硬件和软件的总体架构和不同模块的配置;仿真结果表明所设计滑模控制器相比于PID控制器有更好的控制效果,并给出了其在半实物仿真平台上用来研究四旋翼无人机姿态控制的可行性。     

用超声波测距的四旋翼无人机三维防撞系统设计

针对四旋翼无人机碰撞事故多发的问题,设计了一款基于超声波测距原理的四旋翼无人机三维防撞系统。本系统利用超声波技术实现测距,将无人机与周围障碍间三维空间方向上的距离信息采集到控制系统,控制系统根据距离信息控制悬停信号与遥控信号,实现无人机自主防撞,最后通过试验证明了该系统的正确性与合理性。该系统满足了四旋翼无人机安全防撞要求,且具有重量轻、体积小、精度高、安全可靠等特点。     

Editorial of special issue on unmanned aerial vehicles (UAVs)

UAVs have witnessed unprecedented levels of growth during the last decade. Projections and predictions suggest that during the next 5-10 years growth will continue to rapidly increase, while the spectrum of UAV utilization will be dominated by civil and public domain applications, ranging from search and rescue, emergency response, disaster management, infrastructure monitoring and protection, precision agriculture, surveillance and reconnaissance, cartography, etc. This special issue on UAVs consists of six invited and peer reviewed papers. The main focus of the issue is on multi-UAV teams, a research area that has attracted attention due to the fact that a team of unmanned vehicles may accomplish, collectively, tasks that may be difficult or impossible by a single UAV to complete. The first four papers focus on: Flocking control of a fleet of UAVs; distributed output feedback stationary consensus of multi-vehicle systems in unknown environments; consensus controller for multi-UAV navigation; and ranging-aided relative navigation of multi-platforms. Collectively, these four papers offer insight to the state of the art in this important topic. The fifth paper on nonlinear robust control of a quadrotor helicopter with finite time convergence addresses challenges related to UAV navigation/control, while the last paper on experimental evaluation of a real-time GPU-based pose estimation system for autonomous landing of rotary wing UAVs introduces a comprehensive methodology that is suitable for real-time autonomous takeoff and landing from stationary and moving ground platforms.     

高空长航时无人机技术发展新思路

根据未来航空发展的战略需要,面向新一代高空长航时无人机的系统设计,十分有必要开展探索性、创新性和面向高空长航时无人机的关键技术研究.提出了高空长航时无人机技术发展的新思路和其瓶颈问题的解决方案.重点从高空长航时无人机多目标组合优化、气动-隐身一体化、能源动力、软件使能自主控制、自主导航、测控和信息传输、空天地多机分布协同等方面给出了可行技术方案和重点研究方向.这些技术的实现可增强高空长航时无人机系统方面的可持续发展能力,支撑和引领相关领域的技术发展.     

面向小型无人机导航的滑模控制算法研究

设计一种简单、高效、稳健的导航算法对无人机来说非常重要。分析了无人机的运动学和动力学特性,提出了一种基于滑模控制理论的非线性导航算法。针对滑模控制中出现的抖振问题,重新进行了控制律设计,并对制导参数进行了优化。实际测试结果表明,所提出的导航控制算法具有良好的性能指标,可跟踪任意航路点,可实现无人机自主飞行。     

无人机导航监控系统设计与实现

针对传统模拟表盘式导航监控系统存在人工估算飞机位置偏差大、模拟表盘读数精度低、人机交互性差等问题,提出了基于数字地图、信号滤波处理和自动航线规划的无人机导航监控系统设计方案,给出了设计原理、系统组成以及实现方法.     

Extreme learning machine terrain-based navigation for unmanned aerial vehicles

Unmanned aerial vehicles (UAVs) rely on global positioning system (GPS) information to ascertain its position for navigation during mission execution. In the absence of GPS information, the capability of a UAV to carry out its intended mission is hindered. In this paper, we learn alternative means for UAVs to derive real-time positional reference information so as to ensure the continuity of the mission. We present extreme learning machine as a mechanism for learning the stored digital elevation information so as to aid UAVs to navigate through terrain without the need for GPS. The proposed algorithm accommodates the need of the on-line implementation by supporting multi-resolution terrain access, thus capable of generating an immediate path with high accuracy within the allowable time scale. Numerical tests have demonstrated the potential benefits of the approach.     

EKF Based Attitude Estimation and Stabilization of a Quadrotor UAV Using Vanishing Points in Catadioptric Images

In recent years, Unmanned Air Vehicles (UAVs) have become more and more important. These vehicles are employed in many applications from military operations to civilian tasks. Under situations where global positioning system (GPS) and inertial navigation system (INS) do not function, or as an additional sensor, computer vision can be used. Having 360° view, catadioptric cameras might be very useful as they can be used as measurement units, obstacle avoidance sensors or navigation planners. Although many innovative research has been done about this camera, employment of such cameras in UAVs is very new. In this paper, we present the use of catadioptric systems in UAVs to estimate vehicle attitude using parallel lines that exist on many structures in an urban environment. After explanation of the algorithm, the UAV modeling and control will be presented. In order to increase the estimation and control speed an Extended Kalman Filter (EKF) and multi-threading are used and speeds up to 40 fps are obtained. Various simulations have been done to present the effectiveness of the estimation algorithms as well as the UAV controllers. A custom test stand has been designed to perform successful experiments on the UAV. Finally, we will present the experiments and the results of the estimation and control algorithms on a real model helicopter. EKF based attitude estimation and stabilization using catadioptric images has found to be a reliable alternative to other sensor usage.     

Guidance and nonlinear control system for autonomous flight of minirotorcraft unmanned aerial vehicles

Small unmanned aerial vehicles (UAVs) are becoming popular among researchers and vital platforms for several autonomous mission systems. In this paper, we present the design and development of a miniature autonomous rotorcraft weighing less than 700 g and capable of waypoint navigation, trajectory tracking, visual navigation, precise hovering, and automatic takeoff and landing. In an effort to make advanced autonomous behaviors available to mini‐ and microrotorcraft, an embedded and inexpensive autopilot was developed. To compensate for the weaknesses of the low‐cost equipment, we put our efforts into designing a reliable model‐based nonlinear controller that uses an inner‐loop outer‐loop control scheme. The developed flight controller considers the system's nonlinearities, guarantees the stability of the closed‐loop system, and results in a practical controller that is easy to implement and to tune. In addition to controller design and stability analysis, the paper provides information about the overall control architecture and the UAV system integration, including guidance laws, navigation algorithms, control system implementation, and autopilot hardware. The guidance, navigation, and control (GN&C) algorithms were implemented on a miniature quadrotor UAV that has undergone an extensive program of flight tests, resulting in various flight behaviors under autonomous control from takeoff to landing. Experimental results that demonstrate the operation of the GN&C algorithms and the capabilities of our autonomous micro air vehicle are presented. © 2009 Wiley Periodicals, Inc.     

An adaptive vision-based autopilot for mini flying machines guidance,navigation and control

The design of reliable navigation and control systems for Unmanned Aerial Vehicles (UAVs) based only on visual cues and inertial data has many unsolved challenging problems, ranging from hardware and software development to pure control-theoretical issues. This paper addresses these issues by developing and implementing an adaptive vision-based autopilot for navigation and control of small and mini rotorcraft UAVs. The proposed autopilot includes a Visual Odometer (VO) for navigation in GPS-denied environments and a nonlinear control system for flight control and target tracking. The VO estimates the rotorcraft ego-motion by identifying and tracking visual features in the environment, using a single camera mounted on-board the vehicle. The VO has been augmented by an adaptive mechanism that fuses optic flow and inertial measurements to determine the range and to recover the 3D position and velocity of the vehicle. The adaptive VO pose estimates are then exploited by a nonlinear hierarchical controller for achieving various navigational tasks such as take-off, landing, hovering, trajectory tracking, target tracking, etc. Furthermore, the asymptotic stability of the entire closed-loop system has been established using systems in cascade and adaptive control theories. Experimental flight test data over various ranges of the flight envelope illustrate that the proposed vision-based autopilot performs well and allows a mini rotorcraft UAV to achieve autonomously advanced flight behaviours by using vision.     

Missile guidance law design using adaptive cerebellar model articulation controller

An adaptive cerebellar model articulation controller (CMAC) is proposed for command to line-of-sight (CLOS) missile guidance law design. In this design, the three-dimensional (3-D) CLOS guidance problem is formulated as a tracking problem of a time-varying nonlinear system. The adaptive CMAC control system is comprised of a CMAC and a compensation controller. The CMAC control is used to imitate a feedback linearization control law and the compensation controller is utilized to compensate the difference between the feedback linearization control law and the CMAC control. The online adaptive law is derived based on the Lyapunov stability theorem to learn the weights of receptive-field basis functions in CMAC control. In addition, in order to relax the requirement of approximation error bound, an estimation law is derived to estimate the error bound. Then the adaptive CMAC control system is designed to achieve satisfactory tracking performance. Simulation results for different engagement scenarios illustrate the validity of the proposed adaptive CMAC-based guidance law.     

Adding Support for Persistence to CLOS via Its Metaobject Protocol

Language-level support for object persistence frees programmers from having to confront a broad class of database issues from within their applications. By virtue of its metaobject protocol, CLOS is a language whose semantics can be tailored by individual programmers. We used the metaobject protocol to extend CLOS with support for object persistence. Our goal was to obtain a version of CLOS with persistence to which we could easily port a commercial geometric CAD modeling system. We describe the design and implementation of our persistence extension and highlight the strengths and weaknesses exhibited by the CLOS metaobject protocol during our experiment. For many aspects of the implementation we found that the metaobject protocol was ideal. In other cases we had to choose among paying a large performance penalty, extending the protocol, and bypassing the protocol by modifying the language implementation directly.