基于VTOL飞行器的滑模控制器设计

垂直起降(Vertical takeoff and landing,VTOL)飞行器是具有3个自由度、2个控制输入的非线性欠驱动控制系统,为了解决严重耦合的VTOL欠驱动系统的输出跟踪问题,首先将VTOL动力学模型解耦成一个最小相位系统和一个非最小相位系统,然后分别针对这两个解耦子系统设计滑模控制器,并通过Lyapunov理论证明系统的稳定性,最后仿真结果表明所设计的滑模控制器实现了对轨迹的无稳态误差跟踪,具有较好的鲁棒性,能够为此类欠驱动系统的输出跟踪问题提供设计参考。     

基于受控拉格朗日函数的垂直起降飞机控制器设计

本文将单欠驱动度力学系统基于受控拉格朗日函数(CL)的控制器设计技术应用到具有输入耦合的垂直起降(PVTOL)飞机的控制问题中. 在显式陀螺力的匹配条件下, 得到的光滑反馈控制律保证了系统几乎全局渐近稳定. 与现有同类方法所得到的结果相比, 该匹配控制器形式更简单而收敛性能得到保持.     

推力矢量垂直短距飞机轨迹优化与控制

推力矢量垂直短距起降(V/STOL)飞机是一种兼顾巡航飞行速度和起降灵活性的新型飞机.本文首先建立了包含执行器饱和的V/STOL飞机动力学模型;然后针对V/STOL飞机在过渡过程阶段面临的强耦合、强非线性的特点,使用梯度下降法进行最优过渡过程轨迹优化并采用适应性矩估计算法(Adam)加速了优化过程;在此基础上,以最优轨迹为基础设计前馈控制器,同时通过对比真实飞行状态与所设计的最优状态给出反馈补偿量,保证了实际的过渡过程沿着最优轨迹进行.经过仿真实验可以发现,该方法具有过渡过程时间短、姿态平稳、鲁棒性强的优点.     

输出重定义方法设计垂直/短距起降飞机高度控制器

垂直/短距起降飞机是一类典型的非最小相位系统.系统的负调特性使得飞机高度响应比较缓慢,并且会在初始阶段响应为负,从而出现不期望的掉高现象.针对该问题,本文设计了新的最小相位输出预估控制器,通过调节近似输出零点的方法提高系统的动态响应;对于负调部分,采用两步参数整定的方法设计PID控制器,达到抑制负调的作用.最后,对飞机的高度俯仰控制进行了仿真验证,结果表明设计的控制器对飞机高度初始负调具有明显的抑制作用,并且缩短了回复上升所需的时间.     

垂直/短距起降飞机的轨迹跟踪控制器设计

针对垂直/短距起降飞行器在悬停状态下滚转力矩与横侧向推力存在强耦合、系统具有非最小相位特性的问题,本文设计了轨迹跟踪控制器.首先利用坐标变换和输入输出线性化将系统分解成最小相位子系统和非最小相位子系统.对非最小相位子系统,采用稳态系统中心的方法求解理想内部动态,并跟踪系统理想内模设计了LQR控制器,使得内部动态有界;对最小相位子系统设计了高增益控制器使得外部动态渐进稳定.仿真结果表明本文设计的控制器对给定轨迹和飞行器机动轨迹都有较好的跟踪效果,验证了控制器的有效性.     

基于Serret-Frenet坐标系的翼伞系统轨迹跟踪控制

基于翼伞系统归航轨迹的特点,采用Serret-Frenet坐标系表示距离“平衡”轨迹的偏差,得到线性时不变的误差运动方程．由此误差方程可以得到控制量与轨迹偏差之间的传递函数,直接进行轨迹控制器的设计．对于控制器输入所需的轨迹偏差和偏差率可以采用解析的方法近似求解,极大地简化了计算．整个设计流程简单明了,采用PD控制器进行轨迹跟踪的算例表明此套方法的有效性．     

基于输入约束一致性算法的多无人机编队控制

针对多无人机系统的编队控制问题,提出了一种基于级联系统理论及输入约束一致性算法的控制方法。首先,给出了垂直起降无人机系统的一般性模型。然后,基于级联系统理论将复杂的一般性模型化简成级联形式,针对级联形式模型,利用双曲正切函数的有界性质,在控制器设计时引入双曲正切函数设计了一致性控制算法。最后基于所设计的输入约束一致性控制算法,设计编队控制算法研究了多无人机编队控制问题。基于Matlab仿真平台对所提控制方法进行验证,仿真结果表明在所设计的一致性控制算法作用下,系统中所有的状态都能够趋于一致。基于所设计的输入约束一致性算法,所提编队控制算法可以实现空间中的无人机保持指定的编队队形飞行。     

飞机牵引机器人路径跟踪模糊控制

为了提高飞机地面自动导航路径跟踪的控制精度,提出了基于模糊自适应控制的智能飞机牵引机器人纯追踪路径跟踪方法。首先建立了牵引机器人-飞机两轮简化模型,进行了路径跟踪运动分析;基于此分析,以牵引机器人-飞机系统运动速度和轨迹误差为输入,以预测距离为输出,通过模糊自适应控制实时调整纯追踪算法预测距离,设计了基于自适应模糊控制的路径跟踪控制器;通过几何仿真和虚拟样机仿真两种方法分别对所提出的方法进行了验证。结果表明,牵引机器人-飞机系统在变速运动时,路径跟踪的轨迹误差能控制在0.5 m左右,完全满足飞机地面自动牵引滑行的精度要求,验证了所提方法的有效性和适应性。     

输入受限四旋翼飞行器的模糊自适应动态面轨迹跟踪控制

针对输入受限条件下四旋翼飞行器的轨迹跟踪控制问题,考虑系统存在模型动态不确定和未知外界干扰的情况,提出一种模糊自适应动态面轨迹跟踪控制方法.该方法设计干扰观测器估计位置模型中复合扰动项,利用模糊系统逼近姿态模型中不确定项和外界干扰,并引入双曲正切函数和辅助系统处理输入受限问题,结合反演法和动态面技术设计轨迹跟踪控制器,以降低控制算法的复杂性,最后选取李雅普诺夫函数证明闭环系统所有信号一致最终有界.应用大疆M100飞行器模型进行仿真验证,结果表明所设计的控制器能够有效处理模型动态不确定和未知外界干扰问题,避免飞行器工作过程中因输入饱和导致执行器失效现象,精确地完成轨迹跟踪控制任务.     

基于智能优化算法的Pendubot轨迹规划与控制方法设计

以垂直Pendubot为研究对象,提出一种基于智能优化算法的轨迹规划与控制方法,以解决Pendubot控制过程中难以从摇起区过渡至平衡区的问题.为Pendubot的驱动连杆规划一条从初始角度到中间角度的正向轨迹和一条从中间角度到目标角度的反向轨迹.欠驱动连杆在系统耦合关系作用下进行运动,对应的Pendubot末端点也运动至相应位置.通过遗传算法优化轨迹参数,将正向和反向轨迹拼合为一条由初始角度到目标角度的驱动连杆轨迹的同时,对应的Pendubot末端点轨迹拼合为一条由垂直向下平衡位置到垂直向上平衡位置的完整轨迹,然后设计跟踪控制器跟踪优化后的驱动连杆轨迹至目标角度,由于耦合关系的存在,Pendubot末端点也运动至垂直向上平衡位置.由于Pendubot受重力作用,其末端点很难长时间稳定在垂直向上平衡位置,故设计镇定控制器,实现Pendubot末端点在垂直向上平衡位置的镇定控制.最后通过仿真实验验证所提出方法的有效性,并通过对比说明所提出方法在奇异点规避、控制器设计和控制效果方面的优势.     

Integrated Guidance and Feedback Control of Underactuated Robotics System in SE(3)

An integrated guidance and feedback control scheme for steering an underactuated vehicle through desired waypoints in three-dimensional space, is developed here. The underactuated vehicle is modeled as a rigid body with four control inputs. These control inputs actuate the three degrees of freedom of rotational motion and one degree of freedom of translational motion in a vehicle body-fixed coordinate frame. This actuation model is appropriate for a wide range of underactuated vehicles including spacecraft with internal attitude actuators, vertical take-off and landing (VTOL) aircraft, fixed-wing multirotor unmanned aerial vehicles (UAVs), maneuverable robotic vehicles, etc. The guidance problem is developed on the special Euclidean group of rigid body motions, SE(3), in the framework ofgeometric mechanics, which represents the vehicle dynamics globally on this configuration manifold. The integrated guidance and control algorithm selects the desired trajectory for the translational motion that passes through the given waypoints, and the desired trajectory for the attitude based on the desired thrust direction to achieve the translational motion trajectory. A feedback control law is then obtained to steer the underactuated vehicle towards the desired trajectories in translation and rotation. This integrated guidance and control scheme takes into account known bounds on control inputs and generates a trajectory that is continuous and at least twice differentiable, which can be implemented with continuous and bounded control inputs. The integrated guidance and feedback control scheme is applied to an underactuated quadcopter UAV to autonomously generate a trajectory through a series of given waypoints in SE(3) and track the desired trajectory in finite time. The overall stability analysis of the feedback system is addressed. Discrete time models for the dynamics and control schemes of the UAV are obtained in the form of Lie group variational integrators using the discrete Lagrange-d’Alembert principle. Almost global asymptotic stability of the feedback system over its state space is shown analytically and verified through numerical simulations.     

某型涵道无人飞行器控制系统设计

涵道无人飞行器是一种可垂直起降的新型航空器,控制系统是其核心组成部分.从工程应用需求出发,针对涵道飞行器设计了一种具有高性能价格比、结构紧凑、低功耗的控制系统;提出基于PID的飞行控制策略并给出了控制系统总体结构,设计硬件与软件系统实现飞行器的姿态和轨迹控制,并进行飞行仿真试验验证.验证结果表明,设计方案合理可行,具有很高的应用价值.     

An observer for a velocity-sensorless VTOL aircraft with time-varying measurement delay

This paper presents a kind of state observer for a velocity-sensorless vertical take-off and landing (VTOL) aircraft with bounded time-varying delay in its measurement outputs. The proposed observer predicts current state variables based on the delayed outputs, and the estimated state variables can be considered as the actual state variables for feedback control scheme design. Since the delay is time-varying, compared to the constant delay case, different analysis theory must be employed. Under the assumption that the delays are identical for different outputs and bounded input, the asymptotic convergence property of the estimation error based on Lyapunov–Razumikhin theorem is proved. A relative large time delay for the VTOL aircraft in the outputs has been tested in the numerical simulation, and the simulation results show the effectiveness of the proposed observer.     

On improvement of transient performance in tracking control for a class of nonlinear systems with input saturation

This paper studies the technique of the composite nonlinear feedback (CNF) control for a class of cascade nonlinear systems with input saturation. The objective of this paper is to improve the transient performance of the closed-loop system by designing a CNF control law such that the output of the system tracks a step input rapidly with small overshoot and at the same time maintains the stability of the whole cascade system. The CNF control law consists of a linear feedback control law and a nonlinear feedback control law. The linear feedback law is designed to yield a closed-loop system with a small damping ratio for a quick response, while the nonlinear feedback law is used to increase the damping ratio of the closed-loop system when the system output approaches the target reference to reduce the overshoot. The result has been successfully demonstrated by numerical and application examples including a flight control system for a fighter aircraft.     

可垂直起降、高速前飞的飞行器设计与控制

本文设计了一种具有垂直起降、悬停和高速前飞能力的飞行器.这种飞行器通过模态转换,既能够实现类似传统四轴飞行器的垂直起降,又能够实现类似固定翼飞行器的高速前飞.同时本文针对这种飞行器设计了模态转换控制律;仿真试验验证了设计方案和控制律的有效性.     

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。     

Output tracking control for a velocity-sensorless VTOL aircraft with measurement delays

In this paper, we develop a non-linear controller to achieve output tracking for a velocity-sensorless vertical take-off and landing (VTOL) aircraft in the presence of measurement delays. By applying the Pade approximation technique, the original controlled system is transformed into an augmented dimension system without any time delay. After constructing full-order observers, error coordinate transformation, and system decomposition, the tracking problem of the newly transformed system is changed into the stabilisation problem of two non-minimum phase subsystems and one minimum phase subsystem. The resulting controller not only forces the VTOL aircraft to asymptotically track the desired trajectories, but also drives the unstable internal dynamics, which stands for the non-minimum property of VTOL aircraft, to follow the causal ideal internal dynamics (IID) solved via the stable system centre (SSC) method. Numerical simulation results illustrate the effectiveness of the proposed controller.     

基于一阶不确定项估计律的机械臂鲁棒控制研究

针对多自由度机械臂控制系统的模型参数误差、关节摩擦力以及外部输入扰动等不确定项,设计了一类一阶误差估计律;结合基于机构动力学名义模型的输入输出反馈线性化控制算法,对六自由度刚性机械臂的时变轨迹跟踪控制进行了研究,理论上证明了设计的鲁棒控制器是全局渐进稳定的.仿真结果表明该控制策略对系统的各类不确定项具有很好的鲁棒性,能够实现高精度的轨迹跟踪控制.     

基于终端不变集的 Markov 跳变系统约束预测控制

针对离散 Markov 跳变系统, 研究带输入输出约束的有限时域预测控制问题. 对于给定预测时域内的每条模态轨迹, 设计控制输入序列, 驱动系统状态到达相应的终端不变集内, 在预测时域外, 则寻求一个虚拟的状态反馈控制器以保证系统的随机稳定性, 在此基础上, 分别给出了以线性矩阵不等式 (LMI) 描述的带输入、输出约束预测控制器的设计方法.     

A Lie-Backlund approach to equivalence and flatness of nonlinearsystems

A new system equivalence relation, using the framework of differential geometry of jets and prolongations of infinite order, is studied. In this setting, two systems are said to be equivalent if any variable of one system may be expressed as a function of the variables of the other system and of a finite number of their time derivatives. This is a Lie-Backlund isomorphism. The authors prove that, although the state dimension is not preserved, the number of input channels is kept fixed. They also prove that a Lie-Backlund isomorphism can be realized by an endogenous feedback. The differentially flat nonlinear systems introduced by the authors (1992) via differential algebraic techniques, are generalized and the new notion of orbitally flat systems is defined. They correspond to systems which are equivalent to a trivial one, with time preservation or not. The endogenous linearizing feedback is explicitly computed in the case of the VTOL aircraft to track given reference trajectories with stability