Robust tracking control for an air-breathing hypersonic vehicle with input constraints

The focus of this paper is on the design and simulation of robust tracking control for an air-breathing hypersonic vehicle (AHV), which is affected by high nonlinearity, uncertain parameters and input constraints. The linearisation method is employed for the longitudinal AHV model about a specific trim condition, and then considering the additive uncertainties of three parameters, the linearised model is just in the form of affine parameter dependence. From this point, the linear parameter-varying method is applied to design the desired controller. The poles for the closed-loop system of the linearised model are placed into a desired vertical strip, and the quadratic stability of the closed-loop system is guaranteed. Input constraints of the AHV are addressed by additional linear matrix inequalities. Finally, the designed controller is evaluated on the nonlinear AHV model and simulation results demonstrate excellent tracking performance with good robustness.     

Adaptive back-stepping pitch angle control for wind turbine based on a new electro-hydraulic pitch system

A new electro-hydraulic pitch system is proposed to smooth the output power and drive-train torque fluctuations for wind turbine. This new pitch system employs a servo-valve-controlled hydraulic motor to enhance pitch control performances. This pitch system is represented by a state-space model with parametric uncertainties and nonlinearities. An adaptive back-stepping pitch angle controller is synthesised based on this state-space model to accurately achieve the desired pitch angle control regardless of such uncertainties and nonlinearities. This pitch angle controller includes a back-stepping procedure and an adaption law to deal with such uncertainties and nonlinearities and hence to improve the final pitch control performances. The proposed pitch system and the designed pitch angle controller have been validated for achievable and efficient power and torque regulation performances by comparative experimental results under various operating conditions.     

Prescribed performance fuzzy back-stepping control of a flexible air-breathing hypersonic vehicle subject to input constraints

Journal of Intelligent Manufacturing - The design of prescribed performance fuzzy back-stepping tracking control for a flexible air-breathing hypersonic vehicle (FAHV) with actuator constraints is...     

Composite predictive flight control for airbreathing hypersonic vehicles

The robust optimised tracking control problem for a generic airbreathing hypersonic vehicle (AHV) subject to nonvanishing mismatched disturbances/uncertainties is investigated in this paper. A baseline nonlinear model predictive control (MPC) method is firstly introduced for optimised tracking control of the nominal dynamics. A nonlinear-disturbance-observer-based control law is then developed for robustness enhancement in the presence of both external disturbances and uncertainties. Compared with the existing robust tracking control methods for AHVs, the proposed composite nonlinear MPC method obtains not only promising robustness and disturbance rejection performance but also optimised nominal tracking control performance. The merits of the proposed method are validated by implementing simulation studies on the AHV system.     

小型无人直升机反步自适应控制

针对具有强非线性、高度耦合以及参数不确定性特点的小型无人直升机系统,提出一种基于小脑模型关节控制器（Cerebellar Model Articulation Control,CMAC）神经网络的自适应反步控制方法,该方法采用小脑模型关节控制器神经网络在线学习系统不确定性以及反步控制中各阶虚拟控制量的导数信息,设计鲁棒控制项克服CMAC神经网络在线学习系统不确定性的误差,控制律由反步法回归递推得到。仿真结果表明,在模型参数不确定和存在较大误差的情况下,所设计的控制律具有理想的姿态跟踪性能以及良好的鲁棒性。     

MIMO纯反馈受限系统无模型非线性比例反演控制

针对模型未知的MIMO纯反馈系统,提出一种新的控制设计方案.该方案基于预设性能控制思想设计非线性比例控制器,并将其引入反演设计的每一步,以构建非线性比例反演控制器,并融合考虑了模型未知、状态受限、输入受限以及预设性能的需求,且无需引入任何逼近理论和自适应控制等技术即可保证系统具有良好的抗扰性和鲁棒自适应性,控制器结构极为简单.最后,基于Lyapunov稳定性定理证明了闭环系统所有信号一致有界,仿真结果验证了所提出设计方案的可行性和有效性.     

Distributed low-complexity output feedback tracking control for nonlinear multi-agent systems with unmodeled dynamics and prescribed performance

This paper investigates the prescribed performance distributed output consensus problem under directed graphs. With the utilisation of a filter, the original system of each follower can be converted into a strict-feedback system. Then, we design a prescribed performance output feedback distributed control protocol by applying the backstepping approach in the converted system. The proposed protocol can guarantee that the consensus tracking error of each agent evolves in predefined decaying bounds to achieve the prescribed performance, that is, the consensus tracking error of each agent converges to a predetermined residual set at a convergence rate no less than a prespecified value and exhibiting a maximum overshoot less than a preassigned constant. Moreover, during the process of consensus, all the signals in the closed-loop system are globally uniformly bounded. A simulation example is given to verify the effectiveness of the proposed control protocol.     

Adaptive Fuzzy Back-stepping Control of a Flexible Air-breathing Hypersonic Vehicle Subject to Input Constraints

The design of an adaptive fuzzy back-stepping tracking control for flexible air-breathing hypersonic vehicle (FAHV) with actuator constraints is discussed. Fuzzy logic systems (FLSs) are applied to approximate the total uncertainty of FAHV model. The minimal-learning-parameter (MLP) algorithms are applied for FLSs to reduce the quantity of calculation. For the sake of preventing explosion of differentiation term in back-stepping control, the derivatives of virtual control laws can be calculated by sliding mode differentiators. Particularly, the novel auxiliary systems are explored to cope with the inputs saturation. Finally, reference trajectory tracking simulation shows the auxiliary systems have better performances than the existing algorithms when the inputs are saturated.     

飞机俯仰运动自抗扰控制器设计

提出了利用自抗扰控制器在大包线范围内设计飞机俯仰运动控制器的新方法．利用二阶自抗扰控制器补偿系统模型扰动和外扰，实现了纵向运动俯仰角变量的跟踪控制．自抗扰控制器直接依据飞机的非线性模型，符合飞机动力学模型摄动大的特点，在很大的包线范围内不需要改变控制器的结构和参数，简化了飞行控制律的设计过程．大包线范围内的仿真结果表明，系统具有良好的动态和稳态性能，控制器具有很强的鲁棒性，为解决大包线范围内的飞行控制问题提供了一种有效的新途径．     

3RPS/UPS并联机器人神经网络观测器反演控制

为了增强4D互动立体游戏仿真模拟平台的刚度和运动性能，将带冗余结构的3RPS/UPS并联机器人应用其中。首先对其结构进行介绍及逆运动学分析，然后针对传统PID控制在控制精度方面的不足，提出了一种基于神经网络观测器的反演控制方法。最后利用MATLAB对其进行建模以及系统仿真实验，并与传统PID控制以及一般的RBF神经网络自适应控制进行对比。由仿真结果可以看出，根据RBF神经网络观测器估计系统状态值，并应用反演控制理论设计控制器，能实现很好的状态观测，从而实现无需速度信号的位置跟踪。该方法也能够在一定程度上提高精度，且其整体控制效果优于传统PID控制器，相比于一般的RBF神经网络自适应控制也有了一定的改进。     

Prescribed-performance fault-tolerant control for feedback linearisable systems with an aircraft application

This paper investigates fault-tolerant control (FTC) for feedback linearisable systems (FLSs) and its application to an aircraft. To ensure desired transient and steady-state behaviours of the tracking error under actuator faults, the dynamic effect caused by the actuator failures on the error dynamics of a transformed model is analysed, and three control strategies are designed. The first FTC strategy is proposed as a robust controller, which relies on the explicit information about several parameters of the actuator faults. To eliminate the need for these parameters and the input chattering phenomenon, the robust control law is later combined with the adaptive technique to generate the adaptive FTC law. Next, the adaptive control law is further improved to achieve the prescribed performance under more severe input disturbance. Finally, the proposed control laws are applied to an air-breathing hypersonic vehicle (AHV) subject to actuator failures, which confirms the effectiveness of the proposed strategies.     

随机激励下板球系统建模与有限时间全状态预设性能跟踪控制

研究板球系统受到随机激励时的数学建模与轨迹跟踪控制问题. 首次建立了板球系统的随机数学模型, 并 结合backstepping方法、有限时间预设性能函数、全状态约束及新的预设性能推导方法设计了具有未知输入饱和的 随机板球系统实际有限时间全状态预设性能跟踪控制器, 实现了随机激励下板球系统的有限时间预设性能轨迹跟 踪控制. 所设计的控制器保证了系统跟踪误差能够被预先给定的有限时间性能函数约束, 并且能在任意给定的停息 时间内收敛到预先给定的邻域内. 最后通过仿真实验验证了所设计控制器具有更好的控制效果.     

无人机滑降着陆控制系统设计

针对滑跑型无人机回收阶段对下滑角跟踪以及触地时姿态角的高要求,设计了一种无人机滑降着陆控制方式。首先,给出了滑降控制系统结构图,在此基础上分别进行了滑降横侧向控制器和滑降纵向控制器的设计,具体进行了直线航迹和圆航迹的控制方法以及下滑段的高度控制量算法的分析。然后,进行了滑降着陆控制模式设计,将滑降过程分解为降高、平飞、下滑以及拉平四个阶段分别进行设计,并在拉平阶段给出了俯偏航距仰角控制量与离地高度的关键技术公式。仿真结果表明,该无人机滑降着陆控制系统平飞段偏航距小于5m,接地时偏航距约为0m;平飞段高度跟踪误差为0m,下滑段高度跟踪误差2m;落地姿态角为0.4度。具有高度控制误差小、偏航距离短、落地姿态角安全性高的优点,能满足滑跑无人机对滑降阶段的控制要求。     

A low-complexity global approximation-free control scheme with prescribed performance for unknown pure feedback systems

A universal, approximation-free state feedback control scheme is designed for unknown pure feedback systems, capable of guaranteeing, for any initial system condition, output tracking with prescribed performance and bounded closed loop signals. By prescribed performance, it is meant that the output error converges to a predefined arbitrarily small residual set, with convergence rate no less than a certain prespecified value, having maximum overshoot less than a preassigned level. The proposed state feedback controller isolates the aforementioned output performance characteristics from control gains selection and exhibits strong robustness against model uncertainties, while completely avoiding the explosion of complexity issue raised by backstepping-like approaches that are typically employed to the control of pure feedback systems. In this respect, a low complexity design is achieved. Moreover, the controllability assumptions reported in the relevant literature are further relaxed, thus enlarging the class of pure feedback systems that can be considered. Finally, simulation studies clarify and verify the approach.     

Quadrotor Control Via Robust Generalized Dynamic Inversion and Adaptive Non‐Singular Terminal Sliding Mode

A robust two‐loops structured control system design for quadrotor's position/attitude trajectory tracking is proposed. The aim of the outer loop is to provide the roll/pitch tilting commands to the inner loop, which in turns generates the tilting angles that control the quadrotor's center of gravity in the horizontal plane. The outer loop utilizes Robust Generalized Dynamic Inversion (RGDI) of a prescribed asymptotically stable differential equation in the deviation function of the horizontal position coordinates from their reference trajectories. The inner loop employs an Adaptive Non‐singular Terminal Sliding Mode (ANTSM) to control the tilting angles, in addition to controlling the yaw attitude angle and the vertical position coordinate. The proposed scheme solves the singularity avoidance problems of generalized inversion and terminal sliding mode control. The stability of outer and inner loop is ensured by utilizing positive definite Lyapunov energy function for stable tracking performance against parametric variations and bounded unknown external disturbances. Numerous simulations are conducted on a six Degrees of Freedom (DoF) quadrotor model in the presence of parametric variations, un modeled dynamics, and external disturbances.     

高超声速飞行器输入受限反演鲁棒控制

针对执行机构受限条件下高超声速飞行器的控制问题,提出一种鲁棒反演控制设计 方法.设计一种新的辅助系统对跟踪误差和控制律进行补偿,保证执行器受限时跟踪误差的 有界性.为了避免传统反演方法中虚拟导数计算量膨胀问题,引入滑模微分器对虚拟 导数进行求解.为了增强系统的鲁棒性,基于改进反正切跟踪微分器(MATD)设计 一种新型干扰观测器,对系统的不确定项进行估计和补偿.最后,通过实例仿真验证了所提出控制器的有效性.     

Adaptive Anti-saturation Tracking Control with Prescribed Performance for Hypersonic Vehicle

For the hypersonic vehicle with external disturbance, input saturation, model parameter uncertainties and prescribed performance constraint, the tracking control strategy is studied in the thesis. Firstly, a prescribed performance function is introduced into the control design by transforming auxiliary variable errors, which guarantees tracking performance of the control system. On the basis of second-order system model of hypersonic vehicle, an adaptive anti-saturation terminal sliding mode (TSM) controller with prescribed performance is presented by using the adaptive control theory and TSM control. The stability theory of the control law is presented by Lyapunov stability theory and the numerical simulations are conducted to indicate the effectiveness of the proposed control scheme.     

基于级联方法的欠驱动AUV全局K指数3 维直线跟踪控制

采用非线性系统级联方法,提出一种欠驱动自主水下航行器的3维直线跟踪控制算法,首先将3维直线跟踪误差模型分解为水平面运动受垂直面运动扰动的级联结构;然后分别设计俯仰角指令和航向角指令,进一步将平面直线跟踪模型分解为位置跟踪误差受俯仰角/航向角跟踪误差扰动的级联结构,并设计了俯仰角和航向角的跟踪控制律,通过逐级应用级联系统稳定性理论证明了3维直线跟踪误差的全局κ指数稳定性;最后通过数学仿真验证了所提出跟踪控制算法的有效性。     

显式抑制测量误差的改进滑模控制

反馈控制系统中模型不确定性和测量误差的同时出现, 给高精度控制器的设计带来挑战. 经典滑模控制能抵抗一定程度的模型不确定性和输入干扰, 但引入的高增益使得其性能对测量噪声极为敏感, 也容易引起系统强烈抖振. 为此, 本文针对一种典型的角度和角速率测量分别包含高频和低频测量误差条件, 提出了一种改进的基于趋近律的角度跟踪控制方案. 本方案采用低通滤波器来应对高频测量噪声, 同时采用一种新颖的基于模型的测量误差估计器, 来补偿低频测量漂移. 采用Quanser Aero平台进行两自由度角轨迹跟踪控制仿真和实验验证, 并与自抗扰控制等几种典型鲁棒控制方案进行了全面对比, 证实了本文方案性能上的优越性和调参的便捷性.