Fractional Order Exponential Type Discrete-time Sliding Mode Control

International Journal of Control, Automation and Systems - In this paper, a new fractional order exponential type reaching law (FOE-RL) is presented for the uncertain discrete-time system. The...     

基于新型趋近律的动中通系统滑模稳定跟踪控制

根据一类典型的三轴动中通系统的耦合特性及载体扰动特点,提出一种新型滑模趋近律方法,并在此基础上设计了滑模稳定跟踪控制器．理论证明和仿真实验均表明了所设计的基于新型趋近律的滑模稳定跟踪控制器的合理性和有效性．     

飞翼布局无人机分数阶积分滑模姿态控制

针对存在复合干扰的飞翼布局无人机(UAV)姿态控制问题,提出了一种基于分数阶积分滑模与双幂次趋近律的姿态跟踪控制方案.结合分数阶微积分及滑模变结构控制理论,设计了分数阶积分滑模面.为解决传统趋近律收敛时间长和抖振严重等不足,提出一种具有二阶滑模特性且有限时间收敛的双幂次趋近律.在名义控制律的基础上,设计super twisting滑模干扰观测器,实现对复合干扰的估计和补偿,增强内外环控制器应对复合干扰的鲁棒性.为充分利用冗余操纵面与解决非线性舵效问题,在飞行控制系统中引入了非线性控制分配环节.仿真结果验证了所提方案的有效性.     

基于输出反馈滑模控制的分数阶超混沌系统同步

以具有更大秘钥空间的分数阶超混沌系统为驱动系统和响应系统,利用具有实际应用意义的输出反馈滑模控制实现两个系统的同步.通过对同步误差系统方程进行结构分解,在辅助系统的基础上设计具有输出反馈特性的滑模控制律.在分数阶系统稳定性理论基础上利用MATLAB YALMIP工具箱对滑模参数进行整定,并利用分数阶Lyapunov稳定性定理证明了滑模控制律和自适应滑模控制律的稳定性.最后,数值仿真表明了本文方法的有效性和可行性.     

用于离散滑模重复控制的新型趋近律

针对不确定离散时间系统, 提出一种新型的离散趋近律, 构造理想切换动态, 并基于理想切换动态设计离散滑模重复控制器. 在消除系统颤振的同时, 完全抑制周期扰动带来的影响, 改善控制品质. 分别推导了切换函数的绝对收敛层、单调收敛层和拟滑模带的边界, 用于刻画在不同控制器参数下闭环系统的趋近过程和拟滑模运动. 数值仿真和在伺服装置上的实验结果证实了所提出控制方法的有效性.     

基于改进型PI趋近律的无刷直流电机滑模控制

针对无刷直流电机模型参数时变的特性,为解决传统PID控制易受模型参数变化影响的弊端与传统滑模控制(SMC)的抖振问题,将分数阶PI与变速趋近律结合,提出了一种改进型PI趋近律的无刷直流电机滑模控制算法。该算法通过对趋近律的改进,既避免了模型参数变化的影响,又减小了系统输出的抖振。仿真与实验结果表明,与传统滑模控制、传统PI控制相比,具有响应快、鲁棒性强、超调小、抖振小等优点,是一种更优的控制方法。     

一种多幂次滑模趋近律设计与分析

针对传统滑模趋近律使系统存在抖振现象、收敛速度较慢及动态响应不平滑等问题, 提出一种多幂次滑模趋近律.该趋近律通过三个幂次项系数在系统趋近过程不同阶段进行针对性地调节, 使系统动态响应过程的收敛速度大幅度提高, 且无抖振现象.理论验证了其存在性、可达性及稳定性, 并详细推导了趋近速率及干扰稳定界.以航天器姿态机动控制系统为例, 对比仿真结果表明该趋近律下, 系统的动态过程有较大改善并消除了抖振, 且在存在模型不确定性及外加干扰作用下, 系统仍可较快地收敛到平衡点附近的邻域内.     

Fractional‐Order Dynamic Output Feedback Sliding Mode Control Design for Robust Stabilization of Uncertain Fractional‐Order Nonlinear Systems

A robust fractional‐order dynamic output feedback sliding mode control (DOF‐SMC) technique is introduced in this paper for uncertain fractional‐order nonlinear systems. The control law consists of two parts: a linear part and a nonlinear part. The former is generated by the fractional‐order dynamics of the controller and the latter is related to the switching control component. The proposed DOF‐SMC ensures the asymptotical stability of the fractional‐order closed‐loop system whilst it is guaranteed that the system states hit the switching manifold in finite time. Finally, numerical simulation results are presented to illustrate the effectiveness of the proposed method.     

Sliding mode control of uncertain fractional‐order systems: A reaching phase free approach

This paper proposes a sliding surface which renders the system dynamics to start directly from itself without a reaching phase. More specifically, the system dynamics is insensitive to matched disturbances/uncertainties throughout the entire system response. The controller design based on reduced‐order subsystem is still preserved. It is different from integral sliding mode in which the design is based on the full order of the system to reach the same objective. The simulation results of its application to a fractional inverted pendulum system is demonstrated.     

基于积分滑动流形的高阶滑模控制器设计

滑模变结构控制方法因其易实现,鲁棒性强等优点广泛应用于实际控制系统中,讨论了具有积分滑动流形的高阶滑模控制器的设计方法.通过设计含积分滑动流形的高阶滑模面,使系统状态在一阶乃至高阶滑模面上均能达到滑动模态.同时利用高阶滑模面为状态变量设计新的状态空间系统,将原先促使系统状态接近并停留在滑模面上的控制目标,拓展为使高阶滑模状态变量趋近于零的控制目标,并结合最优控制方法来设计等效控制量,利用积分流形设计切换控制的切换面,通过严格证明来证实控制器设计的稳定性.在仿真验证部分采用了一阶倒立摆模型,通过比较常规趋近律滑模控制方法和本文方法的仿真结果,可以得出本文方法在减小系统控制量抖振方面的重要作用和优异效果.     

Minimum Ultimate Band Design of Discrete Sliding Mode Control

The paper presents a generalized understanding on the dynamics of the sliding variable for discrete time sliding mode control systems via a fresh approach involving several bands in the space of the sliding variable. Using this analysis, controller parameters can be obtained once the ultimate band is chosen. It is shown that on choosing the least ultimate band, the control becomes non‐switching and Gao's reaching law becomes identical to Utkin's reaching law. On other occasions, the ultimate band obtained using this approach is clearly less than that obtained in previous works using Gao's reaching law. The analysis is presented for both state feedback and multirate output feedback cases.     

非匹配不确定系统的滑模控制及在电机控制中的应用

针对具有匹配与非匹配不确定的非线性系统,设计基于干扰观测器和多幂次趋近律的滑模控制策略.首先,通过干扰观测器估计系统的不确定,实现估计误差在有限时间内收敛;其次,基于积分型滑模面,并结合多幂次趋近律,设计了连续滑模控制律,避免了传统滑模的抖振问题.与基于单幂次和双幂次趋近律的滑模控制策略相比,所设计的基于多幂次趋近律的控制策略,提高了系统的收敛速度.最后,通过数值仿真和永磁同步电机控制仿真验证了所设计的控制策略的有效性.     

新趋近律的直流微电网母线电压滑模控制设计

随着直流微电网技术的快速发展,直流微电网中母线电压的稳定性控制作为直流微电网正常平稳运行的关键,也成为了研究热点之一;针对直流微电网母线电压外环易受参数摄动和负荷扰动的影响,提出了一种扩张状态扰动观测器ESO(Extend state observer)与新型趋近律的滑模控制器NRSMC(New reaching law sliding mode control)相结合的复合控制器ESO-NRSMC;该控制器采用了一种新型趋近律方法来解决抖振现象与滑模面趋近时间之间的矛盾;同时扩张状态观测器将观测到的扰动值补偿到滑模控制器中,进一步提高控制器的抗扰动能力;还构造了Lyapunov函数来验证所设计的母线电压外环闭环控制系统的稳定性;最后通过仿真证明控制器ESO-NRSMC在微电网系统参数发生变化以及负载扰动的情况下,依然能够实现对直流微电网母线电压的稳定控制,具有较强的优越性和鲁棒性能。     

直流电动机的优化滑模变结构控制

为了改善直流电动机调速的动态性能,减少指数趋近率引起的抖振,提出了一种直流电动机调速的新方法,将滑模变结构控制策略应用于直流电动机调速控制系统.在给定的数学模型基础上,分别设计出了基于指数趋近率和改进的指数趋近率的滑模变结构控制器.通过Matlab中的Simulink工具对两种控制器仿真和比较表明,改进的控制率能够达到良好的速度与位置跟踪效果,其响应时间和调整时间均较小,并且可以进一步有效地削弱抖振.方法具有一定的实用价值.     

采用幂次趋近律的滑模控制稳态误差界

对一类不确定非线性系统采用幂次趋近律的滑模跟踪控制,分别推导了采用Slotine形式的传统滑模面和积分滑模面时的稳态跟踪误差的界.首先,基于Lyapunov方法求出了滑模误差的最终界和系统不确定性、幂次趋近律参数之间定量的数学关系.其次,利用有界输入有界输出稳定的方法,分别求出了采用Slotine形式的传统滑模面和积分...     

快速收敛的非线性SISO系统变结构控制设计

讨论了SISO非线性系统的两种滑模变结构控制设计.分别从线性滑模的趋近率及非线性滑模设计提出了新的方法及相应控制方案.文中设计的线性滑模趋近率,其趋近速度及滑动状态随系统状态变化而变化;非线性滑模从系统收敛速度及动静态性能综合考虑进行了设计.研究结果表明,相比于终端滑模,系统具有显著的快速性,并具有良好的动静态性能.最后通过三个仿真实例验证了该方案的有效性.     

Disturbance Compensation Based Discrete-time Sliding Mode Control with a Reference Trajectory Generator

A novel disturbance compensation based sliding mode reaching law with a reference trajectory generator is presented in this work. Unlike existing similar researches, a reference trajectory generator is added to the reaching law to obtain the target evolution of the switching function. Meanwhile, a high order disturbance estimator is utilized to achieve accurate disturbance rejection. Additionally, by using the nonlinear functions, the controller parameters can be adaptively adjusted in a wise manner. The main merit of the presented method is that it is capable of ensuring a much smaller ultimate bound of the switching function, i.e., O(Tⁿ⁺¹) order accuracy and n is a positive integer, better system robustness, and improved control accuracy. Moreover, system dynamics, including the system states, are theoretically analyzed. The performance improvement of the presented method is verified through a real simulation study.

     

Sliding mode control of a discrete system

Conventional sliding mode control designed on the basis of a continuous system is known to be robust to the plant uncertainties. A realized digital system, however, not only yields chattering, but also may become unstable by a long sampling interval. This paper presents a stable discrete sliding mode control insensitive to the choice of sampling interval and not yielding chattering. The control system is designed on the basis of a discrete Lyapunov function and a sufficient condition of the control gain to make the system stable is given. Contrary to the continuous case, the derived switching plane of the control law is different from the sliding mode, and in its neighborhood, the control law is given by the linear state feedback. Simulations show the effectiveness of the proposed method.     

Sliding mode variable structure control for visual servoing system

A visual servoing tracking controller is proposed based on the sliding mode control theory in order to achieve strong robustness against parameter variations and external disturbances. A sliding plane with time delay compensation is presented by the pre-estimate of states. To reduce the chattering of the sliding mode controller, a modified exponential reaching law and hyperbolic tangent function are applied to the design of visual controller and robot joint controller. Simulation results show that the visual servoing control scheme is robust and has good tracking performance.