Precision flight control for a multi-vehicle quadrotor helicopter testbed

Quadrotor helicopters continue to grow in popularity for unmanned aerial vehicle applications. However, accurate dynamic models for deriving controllers for moderate to high speeds have been lacking. This work presents theoretical models of quadrotor aerodynamics with non-zero free-stream velocities based on helicopter momentum and blade element theory, validated with static tests and flight data. Controllers are derived using these models and implemented on the Stanford Testbed of Autonomous Rotorcraft for Multi-Agent Control (STARMAC), demonstrating significant improvements over existing methods. The design of the STARMAC platform is described, and flight results are presented demonstrating improved accuracy over commercially available quadrotors.     

Design and implementation of a leader-follower cooperative control system for unmanned helicopters

In this paper, we present a full scheme for the cooperative control of multiple unmanned aerial vehicle (UAV) helicopters. We adopt the leader-follower pattern to maintain a fixed geometrical formation while navigating the UAVs following certain trajectories. More specifically, the leader is commanded to fly on some predefined trajectories, and each follower is controlled to maintain its position in formation using the measurement of its inertial position and the information of the leader position and velocity, obtained through a wireless modem. More specifications are made for multiple UAV formation flight. In order to avoid possible collisions of UAV helicopters in the actual formation flight test, a collision avoidance scheme based on some predefined alert zones and protected zones is employed. Simulations and experimental results are presented to verify our design.     

System identification and improved internal model control for yaw of unmanned helicopter

The sea breeze is a low-frequency disturbance that severely damages the stability of small unmanned helicopters operating over the sea, especially for the yaw control, which is highly sensitive to disturbance. General internal model control is an appropriate method for dealing with this kind of operation conditions, whereas conventional internal model control cannot eliminate the tracking errors between a nominal model and a real model. In coping with unknown dynamics and low-frequency gust disturbances for small helicopters, this paper proposes a novel robust controller constructed with system identification and integrator-based improved general internal model. As a refinement of the conventional frame, the proposed control scheme extends the applicable scope of a controlled plant from a priori known dynamic to an unknown dynamic. Furthermore, under the proposed controller, it is guaranteed that the tracking error between the actual model and the nominal model converges to zero asymptotically. Finally, the effectiveness and advantage of the proposed control scheme are verified through comparative practical flight tests.     

一种线性自抗扰控制器的无人直升机姿态控制方法研究

针对无人直升机模型复杂,控制器难于设计,易受外界干扰等问题,本文在建立亚拓系列直升机动力学模型基础上,提出了一种改进的二阶线性自抗扰控制器。首先,将线性扩张状态观测器用于估计影响输出结果的扰动,并加入跟踪微分器。然后,改进了控制器结构与反馈补偿系数,使直升机姿态角能够更快地响应所输入的指令,并能够按设定的角度飞行,以完成要求的任务;最后,通过引入白噪声干扰模块,来验证本文控制器的抗干扰能力。对比仿真结果表明,本文所提出的控制器对于无人直升机的姿态角有较好的控制效果,优于其他两种控制器。特别是在噪声干扰的条件下,也有较好的动态性能和鲁棒性。     

基于网络的飞行传感器仿真系统研究

提出了一种基于TCP／IP协议的传感器仿真系统,模拟无人机实际飞行中各类传感器的信导和电气特性,解决了全数字无人机飞行仿真系统中对飞机传感器进行实时仿真的问题。     

基于强化学习算法的智能飞控开发系统

无人机控制器的设计开发是一项复杂的系统工程, 传统的基于代码编程的开发方式存在开发难度大、周期长及错误率高等缺点. 同时, 强化学习智能飞控算法虽在仿真中取得很好的性能, 但在实际中仍缺乏一套完备的开发系统. 本文提出一套基于模型的智能飞控开发系统, 使用模块化编程及自动代码生成技术, 将强化学习算法应用于飞控的嵌入式开发与部署. 该系统可以实现强化学习算法的训练仿真、测试及硬件部署, 旨在提升以强化学习为代表的智能控制算法的部署速度, 同时降低智能飞行控制系统的开发难度.     

无人机飞行控制系统模拟器设计

提出了一种基于工业控制计算机开发的某型无人机飞行控制系统模拟器设计;详细介绍了系统设计原理，给出了硬件构成方案、软件功能模块组成和程序流程图，最后分析了测试结果；该模拟器充分利用了当前计算机技术、自动控制技术、系统实时仿真技术和面向对象编程技术，具有功能强大、界面友好、操作灵活的特点。可用于无人机系统先期设计验证或后期测试维护；实际使用情况表明该系统性能良好，完全能够代替真实飞行控制系统进行实时仿真试验。     

飞机飞行控制系统仿真平台建设

飞行控制系统仿真平台作为现代飞机设计中的重要工具,适用于飞控系统研制的全阶段,是飞控系统研究与开发的重要设施。在分析飞控系统仿真平台建设的必要性、基本要求以及适用范围的基础上,给出了一种通用型半物理仿真平台的建设方案,最后指出了建设中需要把握的关键技术。     

非匹配扰动干扰下的无人直升机轨迹跟踪控制

针对小型无人直升机在飞行过程中容易受到非匹配扰动影响的特点,本文设计了一种基于新型滑模控制方法的轨迹跟踪控制器.首先,建立了无人直升机系统的非线性数学模型,并对该模型进行近似反馈线性化处理,同时将模型分为位置和偏航两个子系统;然后,利用扩展扰动观测器对复合扰动以及非匹配扰动的各阶导数的估计值,设计新型时变滑模面,得到滑模控制律,并给出了控制系统的稳定性分析;最后,仿真结果验证了控制方法的有效性和优越性.该新型滑模控制方法的优越性主要体现在:对非匹配扰动具有较强的鲁棒性,以及能有效地抑制抖振现象.     

A flight control system for aerial robots: algorithms and experiments

This paper presents a hierarchical flight control system for unmanned aerial vehicles. The proposed system executes high-level mission objectives by progressively substantiating them into machine-level commands. The acquired information from various sensors is propagated back to the higher layers for reactive decision making. Each vehicle is connected via standardized wireless communication protocol for scalable multi-agent coordination. The proposed system has been successfully implemented on a number of small helicopters and validated in various applications. Results from waypoint navigation, a probabilistic pursuit-evasion game and vision-based target tracking demonstrate the potential of the proposed approach toward intelligent flying robots.