无人机编队队形保持变换控制器设计

研究无人机编队队形保持变换的控制设计问题.由于控制系统队形跟踪应保证姿态的稳定性,针对两架无人机在“长机-僚机”编队结构中的左菱形编队飞行控制系统,为了有效控制飞行队形,保持变换,提出了根据编队飞行的几何关系推导编队相对运动学方程,结合无人机的自动驾驶仪模型建立了相应的编队飞行线性化数学模型.采用PID控制方法分别对速度、航向和高度设计了一种能通过控制编队间距实现队形变换的三维编队队形保持变换的控制器,并进行仿真.仿真结果表明所设计的控制器能够有效地控制无人机编队,在飞行过程中可以稳定地保持队形,并能根据任务要求合理进行编队,并无碰撞,为设计提供了依据.     

基于神经网络的多机协同编队控制器设计

针对多架无人机协同编队飞行控制问题,设计了一种基于BP神经网络的无人机编队飞行控制器.以两机编队为单元,僚机同时跟踪长机和相邻僚机,根据相对位置和参考坐标系统,采用BP神经网络训练得到最佳的PID控制参数,设计三通道PID控制器并对编队系统进行分布式协同控制,使系统快速跟踪指令并保持编队队形.对四架无人机组成的编队系统进行仿真,系统编队可快速保持期望队形,表明设计的编队控制系统具有良好的稳定性和较强的抗干扰能力.     

基于多任务的无人机编队控制研究

考虑到多架无人机编队飞行的特点,将松散编队及协同思想应用到紧密编队控制中,提出了一个三架无人机协同作战编队的飞行控制系统设计方法;在编队飞行动力学模型的基础上,设计了基于特征结构配置的无人机横侧向控制律,进行指定航路的飞行控制;然后,设计编队控制器,两架僚机可紧紧跟随长机并保持队形稳定;仿真结果表明,设计的控制器可以控制多架无人机进行紧密编队飞行,具有一定的实用性和推广价值。     

基于分布式模型预测控制的无人机编队控制

针对多四旋翼无人机编队在巡航飞行过程中队形形成和保持问题,采用分布式模型预测控制方法将该问题转化为在线滚动优化问题.建立线性时不变的编队运动模型,进而在考虑状态和输入约束,不考虑时延、外界干扰、噪声的情况下,利用领航跟随策略设计一种分布式模型预测控制器,通过引入自身和邻居的假设状态轨迹设计代价函数.其中邻居信息的交互是在有向、时不变通信拓扑结构下进行的.基于该控制器,无人机能够在跟踪目标轨迹的同时,快速形成预先设定的队形并保持队形飞行.通过引入终端等式约束保证系统稳定,进而将目标函数作为Lyapunov函数,给出编队系统渐近稳定的充分条件.最后,利用6架无人机仿真验证控制算法的有效性和优越性.     

输入受限下的无人机编队控制方法研究

针对多旋翼飞行器在轨迹跟踪过程中控制输入受限的问题，设计了一种控制输入受限下的四旋翼无人机协同编队分布式控制算法。首先，对于外环位置子系统，基于线性矩阵不等式的方法，设计了输入受限下的多旋翼飞行器的编队控制律，使得所有无人机的位置收敛到所需的编队模式。其次，对于内环姿态子系统，采用基于双曲正切的方法设计控制输入受限的控制律，使多无人机的姿态趋于一致。最后，基于Lyapunov稳定性理论，证明了系统的稳定性，仿真结果表明，所设计的控制器能够达到良好的协同跟踪控制效果。     

基于领航-跟随的有人/无人机编队队形保持控制

针对有人/无人机编队飞行过程中的队形保持问题,采用领航-跟随策略设计一种有人/无人机编队队形保持控制器.首先从编队作战体系和控制原理角度设计有人/无人机编队控制系统结构;然后基于领航有人机与跟随无人机平面位姿的几何关系,建立编队内相对距离-角度运动学模型;最后在考虑僚机控制系统时变扰动的情况下,针对编队运动学模型特点设计动态反馈自适应编队队形保持控制器,并利用李雅普诺夫理论证明编队控制器的稳定性.仿真结果表明,所设计的控制器能够克服僚机控制模型不确定性带来的扰动影响,可以实现编队由初始误差到期望队形的快速调整以及稳定队形的保持.     

基于PID和LQR的四旋翼无人机控制系统研究

为提高四旋翼无人机的飞行稳定性、无人飞行器控制系统的鲁棒性和控制精度,以建立的四旋翼无人机飞行控制系统模型为基础,采用现代控制理论与传统控制论相结合的方法,针对姿态角速率、姿态角分别设计内环LQR(线性二次型调节器)控制器,及外环PID控制的双回路闲环控制器.充分利用PID控制器易于掌握且对模型要求精度低、LQR控制器能改善内回路的动态特性和稳态性能的特点,完成四旋翼无人机的飞行控制.通过实验遴选该双闭环控制器相关参数并进行优化,实验结果表明所设计的双回路控制器控制性能指标良好.     

一种小型倾转旋翼无人机的建模与仿真

传统无人机多为四旋翼无人机和固定翼无人机,现设计一种小型可倾转旋翼无人机,可实现垂直起降与悬停,并能在空中高速巡航。建立该无人机的动力学模型,对该无人机的旋翼飞行模式,设计了基于滑模控制(Sliding Mode Control)的姿态控制器和位置控制器,并通过Matlab仿真和传统的PID算法进行比较验证。仿真结果表明:基于滑模鲁棒控制的无人机,其姿态收敛过程和位置收敛过程都远快于传统控制方法。     

基于鸽群行为机制的多无人机自主编队

受启发于无人机(unmanned aerial vehicle,UAV)编队飞行与生物群体社会性行为的相似性,本文提出了一种基于鸽群行为机制的多无人机自主编队控制方法.首先通过模仿鸽群特有的层级行为,建立了鸽群行为机制模型.该模型在已有群集模型基础上,采用有向图和人工势场理论对鸽群中的拓扑结构和领导机制进行建模.在深入分析无人机自主编队飞行仿生机理的基础上,设计了一种基于鸽群行为机制的无人机自主编队控制器.该控制器以鸽群行为机制模型为核心,还包含两个辅助环节,即控制指令解算器和状态转换器.最后,通过系列仿真实验验证了无人机群可在本文所设计的无人机自主编队控制器作用下形成预期的编队队形,并可在复杂长机运动条件下保持队形.     

变结构三阶一致性无人机编队控制

对多无人机的编队飞行控制问题进行了研究,解决了多无人机编队构成并稳定飞行和编队内某无人机失事情况下其它无人机仍保持队形稳定飞行的问题.首先,基于图论设计编队通讯网络.其次,基于三阶一致性理论设计编队控制器,通过积分得到每架无人机的目标位置和速度.在编队内无人机失事情况下,设计变结构通讯网络,并给出编队通讯结构变化规则.仿真结果表明,上述控制方案能够保证多无人机迅速构成编队并稳定飞行,在编队内无人机失事情况下,能够保证其它无人机依旧按目标路径和编队形状稳定飞行.     

Aerial cooperative transporting and assembling control using multiple quadrotor–manipulator systems

In this paper, a fully distributed control scheme for aerial cooperative transporting and assembling is proposed using multiple quadrotor–manipulator systems with each quadrotor equipped with a robotic manipulator. First, the kinematic and dynamic models of a quadrotor with multi-Degree of Freedom (DOF) robotic manipulator are established together using Euler–Lagrange equations. Based on the aggregated dynamic model, the control scheme consisting of position controller, attitude controller and manipulator controller is presented. Regarding cooperative transporting and assembling, multiple quadrotor–manipulator systems should be able to form a desired formation without collision among quadrotors from any initial position. The desired formation is achieved by the distributed position controller and attitude controller, while the collision avoidance is guaranteed by an artificial potential function method. Then, the transporting and assembling tasks request the manipulators to reach the desired angles cooperatively, which is achieved by the distributed manipulator controller. The overall stability of the closed-loop system is proven by a Lyapunov method and Matrosov's theorem. In the end, the proposed control scheme is simplified for the real application and then validated by two formation flying missions of four quadrotors with 2-DOF manipulators.     

Adaptive prescribed time control for quadrotor formation with stochastic links failure

The formation control for multiple quadrotors subject to maintaining the formation configuration and collision avoidance in the situation of stochastic links failure is investigated in this paper. First, the distributed formation controller is designed, the position controller is developed to manage the desired formation of position, and the attitude controller is developed to control the translation and rotation movements of the quadrotor. Then, in order to avoid the collisions between multiple quadrotors and the obstacles, a potential energy function method is introduced into the quadrotor formation control combined with the nest adaptive control. Inspired by the design of event trigger controller, a communication compensation controller is designed to ensure the stability of quadrotor formation under the condition of random communication interruption and recovery. Moreover, a prescribed time function is designed, which means the convergence time of the formation system can be set in advance. The prescribed time stability of the formation control system is proved by Lyapunov theory. Finally, the simulation results verify the effectiveness and superiority of this method.     

Nonlinear robust adaptive hierarchical sliding mode control approach for quadrotors

This paper exploits a nonlinear robust adaptive hierarchical sliding mode control approach for quadrotors subject to thrust constraint and inertial parameter uncertainty to accomplish trajectory tracking missions. Because of under‐actuated nature of the quadrotor, a hierarchical control strategy is available; and position and attitude loop controllers are synthesized according to adaptive sliding mode control projects, where adaptive updates with projection algorithm are developed to ensure bounded estimations for uncertain inertial parameters. Further, during the position loop controller development, an auxiliary dynamic system is introduced, and selection criteria for controller parameters are established to maintain the thrust constraint and to ensure the non‐singular requirement of command attitude extraction. It has demonstrated that, the asymptotically stable trajectory tracking can be realized by the asymptotically stable cascaded closed‐loop system and auxiliary dynamic system. Simulations validate and highlight the proposed control approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Dynamic modeling and nonlinear tracking control of a novel modified quadrotor

In this article, a nonlinear tracking controller is designed based on Lyapunov stability for a novel aerial robot. The proposed 6‐rotor configuration improves stability and payload lifting capacity of the robot compared with conventional quadrotors while avoiding further complexities in the robot dynamics and steering principles. The dynamical model of the robot is derived using Newton‐Euler method. The model represents a nonlinear, coupled, and underactuated system. The proposed control strategy includes 2 main parts: an attitude controller and a position controller. Both the attitude and position controls are Lyapunov‐based nonlinear tracking controllers that guarantee the asymptotic convergence of the states' tracking errors to zero. Simulation results are presented to illustrate appropriate performance of the closed‐loop system in terms of position/attitude tracking even in the presence of wind disturbance.     

Distributed finite‐time formation control for multiple quadrotors via local communications

This paper investigates finite‐time formation tracking control problem for multiple quadrotors with external disturbance. The states of the virtual leader are not available to all the followers and the network topology is described by a directed graph. The model of each quadrotor is divided into position subsystem and attitude subsystem. Firstly, novel distributed finite‐time state observers are designed to estimate the relative state errors between followers and the virtual leader. Secondly, the values of these observers are used to design controllers that achieve finite‐time robust coordinated tracking in the position subsystem. Thirdly, the terminal sliding mode disturbance observers and finite‐time attitude tracking controllers are proposed, respectively, in the attitude subsystem to estimate the external disturbance and achieve attitude tracking control. The finite‐time stability analysis of the control algorithms is carried out using the Lyapunov theory and the homogeneous technique. Finally, the efficiency of the proposed algorithm is illustrated by numerical simulations.     

基于光滑二阶滑模的可重复使用运载器有限时间再入姿态控制

针对可重复使用运载器(reusable launch vehicle,RLV)的六自由度再入模型,考虑模型不确定和外界干扰对再入姿态控制的影响,提出了一种非线性鲁棒控制策略.首先,根据多时间尺度特性将RLV的再入姿态模型分为姿态角子系统和姿态角速率子系统.其次,对每个子系统分别设计光滑二阶滑模控制器和滑模干扰观测器实现子系统的有限时间稳定.利用干扰观测器可以实现对不确定和外界干扰的精确估计,从而对控制器进行有效的补偿.进而,基于Lyapunov理论证明了整个系统的有限时间稳定.最后,通过仿真验证了提出的控制策略具有良好的控制性能和鲁棒性.     

一种多旋翼飞行器的设计及实验验证

传统多旋翼机具有欠驱动特性,且平移、旋转运动均存在强耦合,极大地限制了飞行器的机动性能．为此本文设计了一种具备全向运动、推力矢量控制飞行、倾转悬停功能的多旋翼飞行器．该飞行器结构为正四面体,4个倾转旋翼模组分别固定于该四面体的4个顶点．每个倾转旋翼模组能够提供矢量推力,从结构上实现了飞行器姿态控制和位置控制的解耦,使得飞行器能够实现3维空间中全姿态的轨迹跟踪．为避免欧拉角控制产生的奇异性,设计了基于四元数的姿态控制器．利用可控性原理分析了旋翼发生故障时飞行器的可控性,证明了相比传统飞行器它具有更高的容错性．样机实验测试了该飞行器的大角度复杂机动动作以及推力矢量控制飞行能力,可实现最大70°的倾转悬停．实验结果表明,该飞行器相比于传统的四旋翼飞行器具备更高的机动性．     

Quaternion-based robust trajectory tracking control for uncertain quadrotors

This paper presents a robust nonlinear controller design approach for uncertain quadrotors to implement trajectory tracking missions. The quaternion representation is applied to describe the rotational dynamics in order to avoid the singularity problem existing in the Euler angle representation. A nonlinear robust controller is proposed, which consists of an attitude controller to stabilize the rotational motions and a position controller to control translational motions. The quadrotor dynamics involves uncertainties such as parameter uncertainties, nonlinearities, and external disturbances and their effects on closed-loop control system can be guaranteed to be restrained. Simulation results on the quadrotor demonstrate the effectiveness of the designed control approach.     

四旋翼无人机SO(3) 滑模变结构姿态控制器设计

为了提高四旋翼无人机SO(3) 控制的动态性能, 对滑模变结构控制在四旋翼无人机SO(3) 姿态控制中的应用进行研究. 首先, 通过对两种四旋翼SO(3) 姿态控制模型进行分析, 确定一种奇异点较少的模型为控制对象; 随后,针对可能出现的控制奇异问题, 设计一种引入调节函数的无奇异积分型滑模面, 得到了滑模稳定性引理; 最后, 利用这种滑模面进行控制器设计和Lyapunov 稳定性分析, 证明了系统全局指数渐近稳定. 仿真结果验证了所提出的设计方案的正确性.

     

全断面硬岩掘进机的推进速度自适应控制

针对全断面硬岩掘进机(TBM)在掘进过程中负载的不确定性和突变性的问题,提出了一种基于BP神经网络的PID控制策略,增强了推进速度对负载扰动的抑制能力.在分析TBM液压推进系统原理和实际掘进参数的基础上,建立了TBM液压推进系统数学模型,设计了基于BP神经网络的TBM推进速度PID控制器,并采用AmeSim和Matlab联合仿真工具搭建TBM推进系统模型,验证不均匀负载突变下推进速度的控制效果.仿真结果表明:相比于传统PID控制,所提出的控制器能减小不确定性扰动对控制系统的影响,并快速跟踪设定值,实现对TBM推进速度的精确控制.