基于非线性指数趋近律的飞行器纵向姿态控制

基于一种非线性函数构造了新型的非线性指数趋近律,将非线性函数加入传统指数趋近律的等速趋近项系数,使等速趋近项系数随系统运动点到切换面的距离从大到小逐步变化,实现系统运动点到达过程由快到慢的变速控制。通过对到达时间的计算和比较,表明非线性指数趋近律缩短了到达时间,间接增强了系统鲁棒性,进一步降低了系统抖振。四旋翼飞行器纵向姿态控制的仿真结果表明了该控制方法的有效性。     

Variable structure control of systems with uncertain nonlinear friction

A new approach to control system design for systems containing sandwiched, uncertain, non-smooth friction is proposed. The method is based on a multi-state backstepping approach to variable structure control design. Stability and robustness properties are investigated and examples are given.     

Variable structure control with sliding mode prediction for discrete-time nonlinear systems

A new variable structure control algorithm based on sliding mode prediction for a class of discrete-time nonlinear systems is presented. By employing a special model to predict future sliding mode value, and combining feedback correction and receding horizon optimization methods which are extensively applied on predictive control strategy, a discrete-time variable structure control law is constructed. The closed-loop systems are proved to have robustness to uncertainties with unspecified boundaries. Numerical simulation and pendulum experiment results illustrate that the closed-loop systems possess desired performance, such as strong robustness, fast convergence and chattering elimination.     

Variable structure control of stochastic systems

In this paper, the problem of variable structure control of stochastic (SVSC) systems is proposed and the corresponding variable structure control strategies with complete and incomplete state information are established. The concepts of stochastic sliding mode and sliding motion band are introduced which may be regarded as the basic characteristics of SVSC systems. Robustness of SVSC systems is considered and a general design procedure for SVSC systems is presented. The effectiveness of the proposed control method is shown by simulation results.     

凸胞型不确定系统的变结构控制

讨论了凸胞型不确定系统的变结构控制,利用LMI方法,给出了滑模面存在的充分条件,并且给出了线性滑模面的显式表达式.所设计的变结构控制律不仅能保证系统在有限时间到达滑模面,并且保证受限在滑模面上的降阶等价系统是D_R稳定的.最后,给出一个设计实例来阐明该控制方法的有效性.     

Variable structure control of discretized continuous-time systems

A discrete-time variable structure control technique is presented for uncertain continuous-time systems. The design algorithm makes use of the concept of time-delay control in order to estimate the effects of the system perturbations inside the switching region. The controller performances have been evaluated by simulation using a benchmark problem proposed in literature. A satisfactory behavior is obtained also in the presence of remarkable uncertainties, showing noticeable robustness with respect to parameter variations and external disturbances. Moreover, the time-response characteristics can be shaped by the designer, properly tuning the control algorithm parameters     

一种不确定离散时间系统的变结构控制方法

针对离散时间系统变结构控制中存在的问题,利用指数趋近律的趋近特性,提出一种新的离散变结构控制方法.利用递推估计的方法设计变结构控制律,有效地抵消了线性系统中慢变不确定性的影响,实现了对慢变非线性系统的控制.该方法克服了以往控制方法中需已知扰动上界的限制,降低了抖振,加快了趋近速度.仿真结果证明了该方法的有效性.     

离散时间系统变结构控制的趋近律问题

针对离散系统变结构控制，提出了两个新的滑模趋近律．应用该趋近设计变结构控制系统，其原点的稳定性和系统的平稳性都优于指数趋近律和比例-等速-变速趋近律．通过仿真例子对此进行了验证．     

Approximation law for discrete-time variable structure control systems

Two approximation laws of sliding mode for discrete-time variable structure control systems are proposed to overcome the limitations of the exponential approximation law and the variable rate approximation law. By applying the proposed approximation laws of sliding mode to discrete-time variable structure control systems, the stability of origin can be guaranteed, and the chattering along the switching surface caused by discrete-time variable structure control can be restrained effectively. In designing of approximation laws, the problem that the system control input is restricted is also considered, which is very important in practical systems. Finally a simulation example shows the effectiveness of the two approximation laws proposed.     

Approximation law for discrete-time variable structure control systems

Two approximation laws of sliding mode for discrete-time variable structure control systems are proposed to overcome the limitations of the exponential approximation law and the variable rate approximation law. By applying the proposed approximation laws of sliding mode to discrete-time variable structure control systems, the stability of origin can be guaranteed, and the chattering along the switching surface caused by discrete-time variable structure control can be restrained effectively. In designing of approximation laws, the problem that the system control input is restricted is also considered, which is very important in practical systems. Finally a simulation example shows the effectiveness of the two approximation laws proposed.     

基于输出反馈的直升机变结构控制律设计

针对直升机的小扰动模型,设计了静态输出反馈滑模控制器（SOFSMC）。利用参考模型,实现了直升机的相关动态指标。针对滑模面的设计问题,将其等价地转化为一组双线性矩阵不等式（BLMI）,并采用迭代线性矩阵不等式（ILMI）技术来求解。针对控制律的综合问题,给出了一种基于单位向量法的控制律,并通过引入线性反馈来保证系统进入滑动模态后线性控制部分与标称系统的线性控制部分的一致性。仿真结果验证了该方法的有效性。     

The structure of nonlinear control systems possessing symmetries

A concept of symmetry is defined for general nonlinear control systems. It is shown, under various technical conditions, that nonlinear control systems with symmetries admit local and/or global decompositions in terms of lower dimensional subsystems and feedback loops. The structure of the individual subsystems is dependent on the structure of the symmetry group; for example, if the symmetry group is Abelian, one of the subsystems is a quadrature. An additional feature of the decomposition is that the state-space dimensions of the subsystems sum to the state-space dimension of the original system.     

带前置滤波器的MRAC系统的变结构控制

变结构控制对参数不确定性,外部干扰和未建模动态具有鲁棒性,并被应用到鲁棒模型参考自适应系统.其缺点是易产生抖振.本文设计一种带有前置滤波器的变结构控制器,改善系统动态性能并消除了抖振.前置滤波器使带有符号函数的控制切换产生连续可测信号,实际控制律是光滑的.控制器设计和不确定性估计中引入辅助信号和带有记忆功能的正规化信号,适当选取控制器参数,所设计的控制器保证了闭环系统稳定性和任意小的跟踪误差.仿真结果表明该算法是有效的.     

Variable structure control of a class of uncertain systems

This brief paper proposes a method for tuning the parameters of a variable structure controller. The approach presented extracts the error at the output of the controller and applies a nonlinear tuning law using this error measure. The adaptation mechanism drives the state tracking error vector to the sliding hypersurface and maintains the sliding mode. In the simulations, the approach presented has been tested on the control of Duffing oscillator and the analytical claims have been justified under the existence of measurement noise, uncertainty and large nonzero initial errors.     

基于变结构控制的固定前置角制导律设计

弹载合成孔径雷达（SAR）的方位成像能力受飞行导弹的观测角影响,其末制导段采用前侧视工作方式。因此,必需合理设计制导律使前侧视条件成立。为了保证末制导段弹目间具有合适的夹角,采用变结构控制方法设计了一种固定前置角制导律,该制导律能够解决合成孔径雷达导引头对于前置角约束的问题。在制导律设计过程中,首先建立了弹目相对运动关系模型和具有终端角度约束时的视线角变化模型;在此基础上采用变结构控制的方法设计了固定前置角制导律;进而,对该固定前置角导引律进行了性能分析,得出了其一般攻击特性;最后,通过弹道仿真论证了其正确性与有效性。     

Design of variable structure control for fuzzy nonlinear systems

In this paper, the variable structure control problem is presented for Takagi–Sugeno fuzzy systems with uncertainties and external disturbances. The sliding surfaces for the T–S fuzzy system are proposed by using a Lyapunov function and a fuzzy Lyapunov function, respectively. And we design the variable structure controllers such that the global T–S fuzzy system confined on the sliding surfaces is asymptotically stable. Two examples are given to illustrate the effectiveness of our proposed methods.     

Chattering-free fuzzy variable structure control for multivariable nonlinear systems

In this paper, a fuzzy logic controller (FLC) based variable structure control (VSC) with guaranteed stability for multivariable systems is presented. It is aimed at obtaining an improved performance of nonlinear multivariable systems. The main contribution of this work is firstly developing a generic matrix formulation of the FLC-VSC algorithm for nonlinear multivariable systems, with a special attention to non-zero final state. Secondly, ensuring the global stability of the controlled system. The multivariable nonlinear system is represented by T-S fuzzy model. The identification of the T-S model parameters has been improved using the well known weighting parameters approach to optimize local and global approximation and modeling capability of T-S fuzzy model. The main problem encountered is that T-S identification method cannot be applied when the membership functions (MFs) are overlapped by pairs. This in turn restricts the application of the T-S method because this type of membership function has been widely used in control applications. In order to overcome the chattering problem a switching function is added as an additional fuzzy variable and will be introduced in the premise part of the fuzzy rules together with the state variables. A two-link robot system and a mixing thermal system are chosen to evaluate the robustness, effectiveness, accuracy and remarkable performance of proposed FLC-VSC method.     

滞后离散广义不确定系统的变结构控制

首先引入一种新的受限系统等价分解形式．将所给的系统分解成两个低维的子系统．其次设计了带有差分补偿器的切换函数，使得系统在准切换流形上的运动渐近稳定．然后在不确定项有界的条件下设计了离散变结构控制律，使得在控制的作用下，系统的解的轨迹于有限步内进入准切换流形的一个邻域内，并最终收敛干原点邻域内的一个小的抖振．最后给出了数值仿真曲线，以说明该综合设计方法的可行性和有效性．     

具连续分布时滞的抛物型系统的变结构控制

基于比较原理,利用推广的向量Hanalay微分不等式,Dini导数,结合Green公式及不等式分析技术,研究一类具分布时滞的抛物型控制系统的变结构控制问题．首先对所导出的滑动模运动方程,在仅要求系数矩阵是个M-矩阵的条件下,获得了滑动模运动方程全局指数稳定性的充分条件,建立了滑动模运动方程全局指数稳定性定理．其次,设计了仅由状态函数描述的变结构控制器,给出了运动轨线到达滑动模态区的时间的估计．     

基于幂次趋近律的一类离散时间系统的变结构控制

针对一类离散时间系统,提出一种变结构控制设计方法.通过构造幂次趋近律,使得系统的准滑动模态不仅能保持步步穿越切换面的基本属性,而且能大幅度削弱抖振,有效地改善控制品质,提高系统的鲁棒性.采样周期越短,该控制方法的效果越明显.仿真实例表明了所设计控制器的可行性和有效性.