涵道式无人机的悬停姿态控制与运动稳定性分析

进行了涵道式无人机的运动稳定性分析,指出无人机在悬停状态下受近地空间、气流颠簸和荷兰滚的影响,导致系统极易出现抖动甚至失控,而优化飞行器的结构参数对于提高飞行器运动稳定性具有重要意义.基于这种分析,从机械结构设计出发,通过Lyapunov指数方法建立飞行器结构参数与系统运动稳定性之间的量化关系,以此指导系统的机械结构设计及控制系统优化,为提高系统执行飞行任务的可靠性和稳定性奠定理论基础.该方法与Lyapunov直接法相比最大的优点是其可构建性,从而为分析其他机器人等非线性系统的运动稳定性提供了一种简单有效的工具.     

SINS在小型无人机测控方面的应用

为了满足小型无人机航姿系统设计需要,本文对捷联式惯导系统特点及其在小型无人机导航制导领域的应用进行了讨论,特别是对捷联惯导系统通过优化算法及由全球定位系统和捷联惯导系统组建的组合式导航系统进行了分析.讨论结果表明,捷联式惯导系统(包括以捷联式惯导系统为基础组建的组合式导航系统)能够满足无人机导航要求,在小型无人机领域具有很好的应用前景.     

基于UKF信息融合的多旋翼飞行器姿态估计

姿态估计是多旋翼飞行控制的基础,为实现多旋翼三轴姿态估计,构建了基于MEMS陀螺、加速度计和磁力计的低成本姿态测量系统.该系统采用STM32F103作为控制器,集成加速度计和陀螺仪MPU6050,磁强计HMC5883作为测量传感器.针对多旋翼飞行器单一传感器无法准确测量姿态信息的问题,提出了基于无迹卡尔曼滤波信息融合的姿态估计算法.以陀螺仪为状态矢量,加速度计和磁强计解算的姿态角为观测矢量,无迹卡尔曼滤波器将陀螺的良好动态性能与加速度计、磁强计的良好静态性能结合起来,提高姿态测量精度,具有良好的动态跟踪性能.通过飞行测试,与高性能成品飞行器的姿态信息做对比,验证和分析该低成本姿态测量系统的有效性.实验结果表明,基于无迹卡尔曼滤波的姿态测量系统实现了动态环境下低成本多旋翼的精密姿态测量,为无人机自主飞行控制奠定了基础.     

基于插补导航的全自主旋翼机设计与控制

为了解决传统旋翼无人机因手动遥操作而导致飞行不稳定的问题,研究了基于插补导航的全自主旋翼机的设计与控制方法。首先,根据导航系统和地面站,获得当前无人机与目标点之间的位置姿态关系;然后基于插补控制算法,利用机载控制器输出相应的能够控制无人机稳定飞行的脉冲宽度信号,实现脱离手动遥操作的四旋翼无人机全自主飞行控制。最后,通过全自主插补导航飞行仿真与实验,验证了该全自主无人机设计的可行性。结果表明,该全自主控制架构能够有效地模拟遥操作信号,实现无人机的全自主飞行控制,且具有更高的稳定性。     

小型四旋翼无人机飞行控制系统设计与实现

为进一步深入研究和开发小型四旋翼无人机搭建飞行控制实验系统,从硬件设计、软件开发和系统调试与飞行试验3个方面对搭建的小型四旋翼无人机飞行控制系统进行较为详细地阐述。飞行试验表明:所设计的飞行控制系统初步实现了对机体姿态的有效控制,为进一步研究自主飞行奠定了基础。     

应用结构奇异值进行频域气动伺服弹性稳定性分析

基于鲁棒气动弹性分析理论,在气动伺服弹性系统中直接应用频域气动力,并引入复数速压摄动,导出了相应的μ分析框架,在此框架下应用结构奇异值理论,提出一种气动伺服弹性稳定临界点预测求解的完全频域方法。该方法既能保证系统结构奇异值的连续性,又可获得较为精确的计算结果。针对某型飞机及其偏航/滚转增稳回路构成的多输入/多输出气动伺服弹性系统的稳定性分析,采用本文方法求得的系统闭环稳定临界点与传统p-k法计算的结果吻合较好。     

基于动态运动基元的微小型四旋翼无人机路径规划

针对微小型四旋翼无人机的路径规划问题,引入运动学习框架,提出了一种基于动态运动基元的路径规划方法。该方法通过对给定运动样本的学习提取出运动基元,并将学习结果推广到新的飞行目标,从而泛化出相应的运动轨迹。有障碍物的情况下,在已有学习基础上通过设计耦合因子规划出避障路径,然后将规划的轨迹点集提供给微小型四旋翼无人机完成路径跟踪飞行任务。该路径规划方法的可行性通过微小型四旋翼无人机不同目标点的飞行任务仿真得到了验证。仿真实验还验证了该方法在三维空间进行有效避障的性能。     

无人机地面目标跟踪系统的建模与控制

对无人机地面目标跟踪系统进行了分析,并建立了各个子系统的数学模型,针对跟踪过程中可能导致目标丢失的两个关键问题--无人机的飞行轨迹和云台摄像机的控制,给出了一种轨迹规划与跟踪算法,该算法既可以使无人机与目标保持一定距离,又保证了无人机在飞行过程中机头始终朝向目标.此外,设计了一种云台摄像机控制方法,该方法利用无人机与目标的相对位姿和目标偏离图像中心的偏差作为反馈信息对云台摄像机进行控制.仿真结果表明本文所设计的无人机地面目标跟踪系统具有良好的性能.     

气动伺服弹性系统结构陷幅滤波器优化设计

为解决飞机气动伺服弹性耦合频率低且随飞机重量构型变化大,使用结构陷幅滤波器改善飞机气动伺服弹性稳定性易于影响飞机操稳特性的问题,建立了一种基于多目标遗传算法的结构陷幅滤波器优化设计方法。以气动伺服弹性系统的弹性模态频响峰值最小作为优化目标,刚体模态频响特性作为设计约束,通过设计罚函数修正个体适应度对陷幅滤波器的频率与阻尼参数进行优化。结果表明:该文方法能够兼顾飞机的气动伺服弹性与刚体运动特性,有利于充分利用高增益控制系统提升飞行性能。     

航天器柔性附件对整器固有振动特性影响因素及规律分析

介绍快速求解含大型柔性附件航天器系统模态的结构动力学方法,通过对多个柔性结构模型缩聚大幅度缩减自由度,集成MATLAB与NASTRAN进行联合仿真分析。遍历附件所有可能工作姿态的系统模态,大幅提高系统模态计算效率。通过该快速求解方法进行仿真实例分析,阐明航天飞行器的系统构型、柔性附件转动角度、本体与柔性附件质量惯量比三方面对柔性附件约束模态与系统模态影响规律。     

Research on Operation of UAVs in Non-isolated Airspace

In order to explore the safe operation of UAVs in non-segregated airspace, a collision risk model for cylindrical UAVs based on conflict areas was constructed and the risk of conflict between manned and unmanned aerial vehicles was researched. According to the results of risk analysis, a strategy for solving the conflict of aircraft is proposed, and the risk assessment experiment of unmanned aerial vehicle (UAV) in non-isolated airspace conflict is carried out. The results show that under the experimental conditions, large unmanned aerial vehicles equipped with ADS-B, TCAS and other airborne sensing systems will indeed interfere with other aircraft in airspace when they enter non-isolated airspace. Especially when the number of aircraft in airspace is large, the automatic avoidance system of UAV will increase the avoidance time and trigger the safety alarm, but the safety level is still acceptable. This indicates that it is relatively safe for UAVs to enter non-isolated airspace under limited conditions. The results can be used as a reference for the safe operation of unmanned aerial vehicle (UAV) in non-isolated airspace.     

Stable hovering of a jellyfish-like flying machine

Ornithopters, or flapping-wing aircraft, offer an alternative to helicopters in achieving manoeuvrability at small scales, although stabilizing such aerial vehicles remains a key challenge. Here, we present a hovering machine that achieves self-righting flight using flapping wings alone, without relying on additional aerodynamic surfaces and without feedback control. We design, construct and test-fly a prototype that opens and closes four wings, resembling the motions of swimming jellyfish more so than any insect or bird. Measurements of lift show the benefits of wing flexing and the importance of selecting a wing size appropriate to the motor. Furthermore, we use high-speed video and motion tracking to show that the body orientation is stable during ascending, forward and hovering flight modes. Our experimental measurements are used to inform an aerodynamic model of stability that reveals the importance of centre-of-mass location and the coupling of body translation and rotation. These results show the promise of flapping-flight strategies beyond those that directly mimic the wing motions of flying animals.     

Complete morphing wing design using flexible-rib system

This study is concerned with the complete design, analysis, functional prototyping and flight testing of a novel morphing wing system for use in a relatively small (<10 kg) unmanned aerial vehicles (UAVs). To achieve improved flight performance with limited weight penalty, camber-adjustable morphing wing was designed using flexible servomotor-actuated mechanisms. The current design, which was originally conceptualized by Monner et al. (Smart structures and materials: industrial and commercial applications of smart structures technologies. Proceedings of SPIE 3326, pp 60–70, 1998), ensures that the airfoil shape of the wing is able to continuously morph between the non-cambered and the cambered configurations. The morphing function of the wing is achieved using a flexible-rib system driven by onboard servomotor-rocker. This unique design of a flexible-rib assembly enables the airfoil of the wing to be accurately morphed to the target configuration. With the aid of aerodynamic and finite element analyses, the flexible rib assembly performance and structural integrity are evaluated and assessed. The design process was in compliance with aircraft design standards, including the Federal Aviation Regulations—Part 23. The functional prototype of the flexible rib morphing-wing enabled UAV was manufactured and assembled and a test plane was ground tested. The success of the entire project, including flight testing of the flexible rib assembly is summarized in this paper.     

扑翼飞行器气动力测量技术研究进展与展望

扑翼飞行器是一种仿照鸟类飞行的新概念小型无人飞行器,区别于传统固定翼和旋翼飞行器,它主要通过机翼扑动与空气相互作用来提供飞行动力,从而实现飞行器的姿态变动。扑翼飞行器气动特性测试的实质是揭示在非定常流场环境下,扑翼飞行器气动力的产生机制,以及相关扑翼飞行器设计参数对气动特性的影响。通过气动试验方法为扑翼飞行器飞行控制和结构优化等研制工作提供数据支持,将对新型扑翼飞行器理论研究以及飞控品质的提升起到巨大的推动作用。     

Dynamics Modeling and Stability Analysis of Tilt Wing Unmanned Aerial Vehicle During Transition

In the transition mode of quad tilt wing-unmanned aerial vehicle (QTW-UAV), the system stability of UAV will change with the tilt angle changes, which will cause serious head drop down. Meanwhile, with the complex air flow and other disturbances, the system is prone to side bias, frying, stall and other kinetic stability problems, hence the system stability analysis has become an urgent problem to be solved. To solve the stability problem, we need the quantitative criteria of system stability and effective tool of stability analysis, and can improve the stability of the motion control by optimizing the structural parameters of the aircraft. Therefore, based on the design of the mechanical structure, the quantitative relationship between the structure parameters of the aerial vehicle and kinetic stability of the system transition mode is established by the Lyapunov exponent method. In this paper, the dynamic modeling of the position and attitude angle is carried out and the stability of the system is analyzed by Lyapunov exponent, the results show that changing the mechanical structure of the system can improve the flight stability for the system transition mode and lay a theoretical foundation for the system stability analysis. Compared with the Lyapunov direct method, this method can be construct easily, has a simple calculation process and so on. We improve the flight stability by optimizing the structure and the experiment confirms that expanding area can enhance flight stability within limits.     

浮基两刚体模型强迫振动动力响应分析

为分析浮基在外力作用下产生的强迫振动对浮基多体系统动力响应影响,将浮基多体系统简化为光滑铰接的两刚体模型,用多体动力学离散时间传递矩阵理论,并编写程序对浮基多体系统动力响应求解。分别计算浮基在周期横摇角强迫振动与波浪作用下浮基两刚体动力响应,获得浮基两刚体系统运动响应曲线。数值模拟结果表明,当横摇角强迫振动幅值、频率增加时,起吊重物的摆动更剧烈,绳索长度变化对重物摆动影响不大。在横向规则波作用下,浮基与重物的摆动幅值随绳索长度、吊臂仰角的增加而增大,随起吊重物质量变化先增大后减小。     

An SoPC-based object tracking quadrotor

In this paper, a quadrotor unmanned aerial vehicle (UAV) is designed and implemented, and the whole control system is realized on an SoPC platform. The dynamic mathematical model of a quadrotor is derived using Euler–Lagrange equations. A simulation is conducted by applying PID controllers to control the derived model to verify that the PID method is able to stabilize a quadrotor. The aircraft is stabilized according to the sensory data from a tri-axis gyroscope and a tri-axis accelerometer providing angular rates and Euler angles, respectively, for the control system. In addition, a CMOS camera and an ultrasonic sensor mounted on the bottom of the aircraft enable the aircraft with functions of detecting and tracking a moving object, while the aircraft is flying. The resulting system can stably fly in indoor environments and track a specific object, satisfying the design and implementation purpose.     

Computational aircraft dynamics and loads

An alternative approach that has the potential to advance classical methods of flight load prediction by combining computational fluid dynamics (CFD), structural flexibility and the interaction of flight control system (FCS) in a multidisciplinary analysis package is described. The method employs the concept of system identification to characterize aircraft dynamics in the state space coordinate system and includes an adaptive control law design methodology. An extended account of the theoretical basis for the new multidisciplinary flight manoeuvre analysis will be presented in one of a seven-volume series on computational mechanics by Argyris and his associates to be published shortly. However, as a precursor to the complete work, a brief account of the theoretical development leading to this loads prediction methodology is included in this paper. The computational effort of this project was supported by IBM of the United States of America.