Finite-time Adaptive Integral Backstepping Fast Terminal Sliding Mode Control Application on Quadrotor UAV

International Journal of Control, Automation and Systems - This paper presents a reliable and novel quadrotor flight control system designed to enhance trajectory tracking performance, robustness...     

永磁同步电机的自适应反演滑模变结构控制

针对永磁同步电机提出一种基于反演的PMSM自适应滑模控制方案.设计基于反演的滑模变结构位置控制器,通过RBF神经网络实现系统参数变化和外部负载扰动等引起的不确定上界值的在线辨识,减小滑模控制器的控制量,并引入饱和函数来减弱系统的抖动现象.理论分析和仿真结果对比表明,基于RBF神经网络的自适应反演滑模控制对参数变化和外部负载扰动具有很好的鲁棒性,永磁同步电动机获得了很好的跟踪效果.     

Higher Order Sliding Mode Controllers With Optimal Reaching

Higher order sliding mode (HOSM) control design is considered for systems with a known permanent relative degree. In this paper, we introduce the robust Fuller's problem that is a robust generalization of the Fuller's problem, a standard optimal control problem for a chain of integrators with bounded control. By solving the robust Fuller's problem it is possible to obtain feedback laws that are HOSM algorithms of generic order and, in addition, provide optimal finite-time reaching of the sliding manifold. A common difficulty in the use of existing HOSM algorithms is the tuning of design parameters: our methodology proves useful for the tuning of HOSM controller parameters in order to assure desired performances and prevent instabilities. The convergence and stability properties of the proposed family of controllers are theoretically analyzed. Simulation evidence demonstrates their effectiveness.     

Transition Flight Modeling of a Fixed-Wing VTOL UAV

This paper describes a complete six-degree-of-freedom nonlinear mathematical model of a tilt rotor unmanned aerial vehicle (UAV). The model is specifically tailored for the design of a hover to forward flight and forward flight to hover transition control system. In that respect, the model includes the aerodynamic effect of propeller-induced airstream which is a function of cruise speed, tilt angle and angle of attack. The cross-section area and output velocity of the propeller-induced airstream are calculated with momentum theory. The projected area on the UAV body that is affected by the propeller-induced airstream is specified and 2D aerodynamic analyses are performed for the airfoil profile of this region. Lookup-tables are generated and implemented in the nonlinear mathematical model. In addition, aerodynamic coefficients of the airframe are calculated by using CFD method and these data are embedded into the nonlinear model as a lookup-table form. In the transition flight regime, both aerodynamic and thrust forces act on the UAV body and the superimposed dynamics become very complex. Hence, it is important to define a method for hover-to-cruise and cruise-to-hover transitions. To this end, both transition scenarios are designed and a state-schedule is developed for flight velocity, angle of attack, and thrust levels of each of the thrust-propellers. This transition state schedule is used as a feedforward state for the flight control system. We present the simulation results of the transition control system and show the successful transition of TURAC in experiment.     

水平欠驱动机械臂的反步自适应滑模控制

针对二自由度水平欠驱动机械臂系统,提出了基于分层滑模控制思想的反步自适应滑模控制方法．该方法能够在不对系统状态模型进行复杂坐标变换,并且没有约束方程限制的前提下实现对欠驱动系统的反馈滑模控制．仿真结果表明了该方法的有效性,而且优化后的控制器具有较好的适应性和控制效果．     

Sliding Mode and PI Controllers for Uncertain Flexible Joint Manipulator

This paper is dealing with the problem of tracking control for uncertain flexible joint manipulator robots driven by brushless direct current motor(BDCM). Flexibility of joint in the manipulator constitutes one of the most important sources of uncertainties. In order to achieve high performance, all parts of the manipulator including actuator have been modeled. To cancel the tracking error, a hysteresis current controller and speed controllers have been developed. To evaluate the effectiveness of speed controllers, a comparative study between proportional integral(PI) and sliding mode controllers has been performed. Finally, simulation results carried out in the Matlab simulink environment demonstrate the high precision of sliding mode controller compared with PI controller in the presence of uncertainties of joint flexibility.     

基于RBFNN的风电机组变桨距反推滑模控制

在风力发电变桨距优化控制问题的研究中,针对具有不确定性的非线性风电机组,设计了基于径向基函数神经网络(RBFNN)的风电机组变桨距反推滑模控制器.首先应用精确反馈线性化理论将原非线性系统模型进行全局线性化处理,再应用RBFNN对不确定项进行逼近,结合滑模控制和反推法,设计反推滑模控制器(BSMC),保证了高风速下风机的稳定性,抑制了不确定项对系统的影响,避免了传统反推法存在的计算复杂问题.通过与传统滑模控制器(SMC)进行仿真对比,结果表明,RBFNN-BSMC能够很好地稳定风电机组的输出功率,具有较强的鲁棒性.     

四旋翼飞行器姿态的自适应反演滑模控制研究

微小型四旋翼飞行器是一种欠驱动、强耦合的非线性系统.针对四旋翼飞行器控制中的姿态控制优化进行研究,建立了四旋翼飞行器完整的姿态运动模型,为提高系统响应速度和抗干扰性,在反演控制基础上与自适应和滑模控制方法相结合,根据Lyapunov稳定性进行控制系统设计,并选取合适的控制参数使所设计的控制系统是渐进稳定的,最终设计了一种基于自适应反演滑模算法的姿态控制器.通过计算机仿真软件进行验证,结果表明所设计的控制器与其它算法相比具有更快的响应时间和很强的鲁棒性.     

独立线控转向电机转角自适应反演滑模控制

针对独立线控转向系统中转向直流电机控制精度低、响应速度慢的问题,以独立线控转向系统转向电机为控制对象,采用自适应反演滑模控制(ABSMC)算法对转向电机转角进行跟踪控制.通过反步法推导控制律,并利用Lyapunov理论证明了闭环系统的稳定性.应用Carsim与Simulink的联合仿真,以横摆角速度不变的变传动比控制为...     

Two-Step System Identification and Trajectory Tracking Control of a Small Fixed-Wing UAV

An approach for obtaining dynamically feasible reference trajectories and feedback controllers for a small unmanned aerial vehicle (UAV) based on an aerodynamic model derived from flight tests is presented. The modeling method utilizes stepwise multiple regression to determine relevant explanatory terms for the aerodynamic coefficients. A dynamically feasible trajectory is then obtained through the solution of an optimal control problem using pseudospectral optimal control software. Discrete-time feedback controllers are further designed to regulate the vehicle along the desired reference trajectory. Simulations in a realistic operational environment as well as flight testing of the feedback controllers on the aircraft platform demonstrate the capabilities of the approach.     

永磁同步电机的自学习滑模反步抗扰控制

针对永磁同步电机(PMSM)速度跟踪控制问题,设计了一种自学习滑模反步抗扰控制方法.该方法设计了基于类Sigmoid函数的改进型跟踪微分器(TD)用于对输入信号和虚拟控制信号进行滤波,避免了对信号反复解析求导产生的微分爆炸问题,并设计了扩张状态观测器(ESO)用于对外界负载扰动进行实时观测估计和补偿.为了削弱抖振和提高...     

基于反演自适应动态滑模的气垫船航向控制

针对全垫升气垫船运动非线性明显、可操纵性差,为改善操控水平,能够准确地按给定航向航行,设计了反演自适应动态滑模的航向控制算法。建立了三自由度全垫升气垫船平面运动数学模型,并给出了航向非线性控制模型。将反演方法与动态滑模相结合,设计新型切换函数,以实现航向的平滑、无抖振控制。最后,在不同外界扰动作用下进行了仿真,试验结果表明,所设计航向控制算法能够提高全垫升气垫船航向的控制精度,具有自适应性强、响应速度快、稳定性好等特点。     

基于反推滑模的船舶动力定位有限时间控制

考虑存在未知外界干扰的船舶动力定位控制问题,提出一种基于有限时间理论的自适应反推非奇异快速终端滑模算法,并对未知干扰进行自适应估计.利用有限时间Lyapunov理论证明了设计的控制律能够保证闭环系统的状态在有限时间内收敛到平衡点附近小的邻域内.仿真结果表明,与传统渐近稳定控制律相比,设计的控制策略保证闭环系统具有更快的收敛速度及更好的稳定性和鲁棒性.此外,通过对干扰的自适应补偿,进一步降低了系统的稳态误差,增强了系统的抗干扰能力.     

Immersion and Invariance-based Sliding Mode Attitude Control of Tilt Tri-rotor UAV in Helicopter Mode

In this paper, we propose an immersion and invariance-based sliding mode controller for a tilt tri-rotor unmanned aerial vehicle subjects to parameter perturbation, unmodeled dynamics, and external disturbances. The control scheme is divided into three parts, including the disturbance observer, the attitude controller, and the control allocation. Firstly, to alleviate the chattering and improve the robustness for attitude control, the observer using immersion and invariance theory is developed to estimate the disturbance. Note that the observer can relax the requirement of disturbance upper bound and guarantee the convergence of the estimation error. Secondly, to improve the dynamic response capability, a sliding mode attitude controller with an adaptive switch function is designed based on the disturbance observer. Thirdly, a hierarchical control allocation algorithm is proposed. The performance improvement is illustrated by comparing with other sliding mode controllers. Simulations and flight experiments are conducted to verify the effectiveness and applicability of the proposed control scheme.

     

Robust Model-Free Control Applied to a Quadrotor UAV

The objective of this paper is to deal with a new technique based on Model-Free Control (MFC). The concept of this controller is to use a basic controller along with an ultra-local model to compensate for system’s uncertainties and disturbances. In this paper, a proposed algorithm is introduced based on an integrated structure between the Nonlinear Integral-Backstepping technique (NIB) and the MFC. The LQR, NIB, LQR-MFC, and NIB-MFC are implemented on a real quadrotor UAV. Various real-time flight tests are conducted to validate the importance of using the MFC side by side with NIB. The proposed combination shows robust performance compared to the other algorithms under fault-free and actuator fault conditions.     

Backstepping Sliding Mode Trajectory Tracking via Extended State Observer for Quadrotors with Wind Disturbance

To overcome nonlinear, underactuated and external wind disturbances problems for the 6-DOF (degrees of freedom) quadrotor unmanned aerial vehicle (UAV) system, a backstepping sliding mode control algorithm based on high-order extended state observer (ESO) is proposed. Based on the hierarchical control principle, the quadrotor UAV dynamic system is decomposed into position subsystem and attitude subsystem to facilitate the backstepping control design. Moreover, the EXO is used to estimate the remaining unmeasurable states and the external wind disturbances online. The advantages of the controllers are that they can not only ensure good tracking performance, but also deal with uncertain external disturbances. To imitate the real situation as much as possible, the external wind disturbances are composed of four basic wind models in this paper. The tracking error and estimate error of the design methods are shown to arbitrarily small by using Lyapunov theory. Finally, the effectiveness and superiority of the proposed control algorithm are proved by the simulation.

     

Subsonic Tests of a Flush Air Data Sensing System Applied to a Fixed-Wing Micro Air Vehicle

Flush air data sensing (FADS) systems have been successfully tested on the nose tip of large manned/unmanned air vehicles. In this paper we investigate the application of a FADS system on the wing leading edge of a micro (unmanned) air vehicle (MAV) flown at speed as low as Mach 0.07. The motivation behind this project is driven by the need to find alternative solutions to air data booms which are physically impractical for MAVs. Overall an 80% and 97% decrease in instrumentation weight and cost respectively were achieved. Air data modelling is implemented via a radial basis function (RBF) neural network (NN) trained with the extended minimum resource allocating network (EMRAN) algorithm. Wind tunnel data were used to train and test the NN, where estimation accuracies of 0.51°, 0.44 lb/ft² and 0.62 m/s were achieved for angle of attack, static pressure and wind speed respectively. Sensor faults were investigated and it was found that the use of an autoassociative NN to reproduce input data improved the NN robustness to single and multiple sensor faults. Additionally a simple NN domain of validity test demonstrated how the careful selection of the NN training data set is crucial for accurate estimations.     

非匹配不确定非线性系统的自适应反演滑模控制

针对一类具有非匹配不确定性的最小相位仿射非线性系统,研究其在未知扰动作用下的调节问题。基于自适应反演设计方法和变结构控制设计了控制方案,实现不确定系统的鲁棒调节。与经典反演设计相比,本方案允许非参数化不确定性,增强了控制系统的鲁棒性。     

Adaptive Backstepping Sliding Mode Control of Tractor-trailer System with Input Delay Based on RBF Neural Network

In this paper, an adaptive sliding mode neural network(NN) control method is investigated for input delay tractor-trailer system with two degrees of freedom. An uncertain camera-object kinematic tracking error model of a tractor car with n trailers with input delay is proposed. Radial basis function neural networks(RBFNNs) are applied to approximate the unknown functions in the error model. A sliding mode surface with variable structure control is designed by using backstepping method. Then, an adaptive NN sliding mode control method is thus obtained by combining Lyapunov-Krasovskii functionals. The controller realizes the global asymptotic trajectories tracking of the kinematics system. The stability of the closed-loop system is strictly proved by the Lyapunov theory. Matlab simulation results demonstrate the feasibility of the proposed method.

     

Generic Adaptive Sliding Mode Control for a Quadrotor UAV System Subject to Severe Parametric Uncertainties and Fully Unknown External Disturbance

International Journal of Control, Automation and Systems - This paper aims to provide a generic robust controller that is able to manipulate all kinds of quadrotor unmanned aerial vehicle (UAV)...