Delay‐dependent robust L2–L∞ filtering of T‐S fuzzy systems with time‐varying delays

This paper considers the problem of robust delay‐dependent L₂–L_∞ filtering for a class of Takagi–Sugeno fuzzy systems with time‐varying delays. The purpose is to design a fuzzy filter such that both the robust stability and a prescribed L₂–L_∞ performance level of the filtering error system are guaranteed. A delay‐dependent sufficient condition for the solvability of the problem is obtained and a linear matrix inequality (LMI) approach is developed. A desired filter can be constructed by solving a set of LMIs. Copyright © 2009 John Wiley & Sons, Ltd.     

Adaptive TS‐FNN control for a class of uncertain multi‐time‐delay systems: The exponentially stable sliding mode‐based approach

This paper presents an adaptive Takagi–Sugeno fuzzy neural network (TS‐FNN) control for a class of multiple time‐delay uncertain nonlinear systems. First, we develop a sliding surface guaranteed to achieve exponential stability while considering mismatched uncertainty and unknown delays. This exponential stability result based on a novel Lyapunov–Krasovskii method is an improvement when compared with traditional schemes where only asymptotic stability is achieved. The stability analysis is transformed into a linear matrix inequalities problem independent of time delays. Then, a sliding mode control‐based TS‐FNN control scheme is proposed to achieve asymptotic stability for the controlled system. Since the TS‐FNN combines TS fuzzy rules and a neural network structure, fewer numbers of fuzzy rules and tuning parameters are used compared with the traditional pure TS fuzzy approach. Moreover, all the fuzzy membership functions are tuned on‐line even in the presence of input uncertainty. Finally, simulation results show the control performance of the proposed scheme. Copyright © 2008 John Wiley & Sons, Ltd.     

基于自适应模糊滑模控制的机器人轨迹跟踪算法

针对控制参数的不确定性以及存在未知外部扰动情况下移动机器人的轨迹跟踪问题,提出一种基于光滑非线性饱和函数的自适应模糊滑模轨迹跟踪控制算法。通过建立不确定非线性移动机器人运动控制模型,利用自适应模糊逻辑系统构建自适应模糊滑模控制器。为了增强轨迹跟踪控制算法对随机不确定外部扰动适应能力的同时削弱滑模控制算法中的输入抖振现象,利用有界输入有界输出(BIBO)稳定的方法,通过带有自适应调节算法的模糊系统对滑模控制律中非线性函数项进行自适应逼近,并设计了模糊系统中可调参数的自适应控制律,保证了控制系统的稳定与收敛。实验结果表明,所设计的控制器对系统参数不确定性和外界扰动均具有较强的轨迹跟踪性能和鲁棒性。与传统的滑模控制算法相比,该算法不仅能有效减小输入抖振而且轨迹跟踪控制精度提高了18.89%。     

Sliding mode control of singularly perturbed Markovian jump delayed systems with nonlinearity

This paper is concerned with sliding mode control (SMC) of a class of time‐delay nonlinear singularly perturbed Markovian jump systems. Firstly, a switching surface function is designed, and a delay‐dependent condition is derived in terms of ?‐independent linear matrix inequality, which guarantees that the resulting sliding mode dynamics is mean‐square exponentially stable. Then an algorithm is given to estimate the stability bound. Moreover, an adaptive SMC law is synthesized to drive the system trajectories onto the designed switching surface in a finite time. Finally, a numerical example is presented to show the effectiveness of proposed method. Copyright © 2012 John Wiley & Sons, Ltd.     

坦克炮控系统自适应模糊滑模控制方法

针对坦克炮控系统这一类非线性和不确定性的复杂对象控制问题,提出一种自适应模糊滑模控制方法.采用滑模控制与模糊逻辑相结合的方法,滑模开关函数的绝对值作为输入组成一维模糊逻辑推理器,它的输出用以在线调整一维模糊控制器的输出增益,依据Lyapunov稳定定理获得最终的控制量.系统中的滑模控制器保证了系统的快速跟踪性能;而模糊控制器抑制了闭环系统的各种扰动,在不牺牲系统鲁棒性的同时达到削弱抖振的目的.从理论上证明了系统的稳定性,并且通过仿真验证了该结果.仿真结果表明,该设计方法大大优于经典设计,而且结构简单,易于设计,为炮控系统实际设计提供了一种可行的方法.     

Robust disturbance attenuation with unknown input observer and sliding mode controller

For a linear system with mismatched disturbance, a robust sliding mode control algorithm using only output feedback is developed in this paper. Although the system with intrinsic issues of unknown input and nonminimum phase is inherited, an improved reduced-order unknown input observer is to be presented in estimating the state of the system. The manipulation of H _∞ control theory along with the implementation of estimated system state can result in robust stabilization with disturbance attenuation when designing integral sliding surface of a system in the sliding mode. A controller is also designed to satisfy the reaching and sliding condition in line with the estimated system state. Finally, a numerical example is explained for showing the applicability of the proposed scheme.     

Direct adaptive control for non‐linear uncertain systems with exogenous disturbances

A direct adaptive non‐linear control framework for multivariable non‐linear uncertain systems with exogenous bounded disturbances is developed. The adaptive non‐linear controller addresses adaptive stabilization, disturbance rejection and adaptive tracking. The proposed framework is Lyapunov‐based and guarantees partial asymptotic stability of the closed‐loop system; that is, asymptotic stability with respect to part of the closed‐loop system states associated with the plant. In the case of bounded energy L₂ disturbances the proposed approach guarantees a non‐expansivity constraint on the closed‐loop input–output map. Finally, several illustrative numerical examples are provided to demonstrate the efficacy of the proposed approach. Copyright © 2002 John Wiley & Sons, Ltd.     

坦克炮控伺服系统的模糊滑模变结构控制

针对坦克炮控伺服系统这一类非线性和不确定性的复杂控制对象,提出一种模糊滑模控制方法.该方法将滑模控制与模糊逻辑相结合,采用滑模开关函数作为输入组成模糊逻辑推理器,它的输出用以在线调整模糊控制器的输出增益,解决了直线伺服系统跟踪性能和鲁棒性能之间的矛盾.从理论上证明了滑动平面的稳定性,并且通过仿真验证了该结果.仿真结果表明该设计方法大大优于经典设计,为炮控伺服系统实际设计提供了一种可行的新方法.     

Sliding mode control of switched hybrid systems with time‐varying delay

This paper is concerned with the sliding mode control of a continuous‐time switched system with time‐varying delay in its state. By using the average dwell time approach and the piecewise Lyapunov function technique, a sufficient condition is first proposed to guarantee the exponential stability of the unforced system with the decay estimate explicitly given. A sufficient condition of the existence of a reduced‐order sliding mode dynamics is derived, and an explicit parametrization of the desired sliding surface is also given. The obtained conditions will be solved using the cone complementary linearization (CCL) method. An adaptive sliding mode controller for the reaching motion is then designed such that the trajectories of the resulting closed‐loop system can be driven onto a prescribed sliding surface and maintained there for all subsequent times. All the conditions obtained in this paper are delay dependent. Finally, two numerical examples are given to illustrate the effectiveness of the proposed theory. Copyright © 2008 John Wiley & Sons, Ltd.     

Sliding mode disturbance observer‐based adaptive control for uncertain MIMO nonlinear systems with dead‐zone

In this paper, an adaptive integral sliding mode control (ISMC) scheme is developed for a class of uncertain multi‐input and multi‐output nonlinear systems with unknown external disturbance, system uncertainty, and dead‐zone. The research is motivated by the fact that the ISMC scheme against unknown external disturbance and system uncertainty is very important for multi‐input and multi‐output nonlinear systems. The system uncertainty, the unknown external disturbance, and the effect of dead‐zone are integrated as a compounded disturbance, which is well estimated using a sliding mode disturbance observer (SMDO). Then, the adaptive ISMC based on the designed SMDO is presented to guarantee the satisfactory tracking performance in the presence of system uncertainty, external disturbance, and dead‐zone. Finally, the designed adaptive ISMC strategy based on SMDO is applied to the attitude control of the near space vehicle, and simulation results are presented to illustrate the effectiveness of the proposed adaptive ISMC scheme using the SMDO. Copyright © 2016 John Wiley & Sons, Ltd.     

开关磁阻电机模糊滑模转速控制

针对开关磁阻电机严重的非线性和数学模型不精确等缺点,提出了一种模糊滑模变结构控制策略。将速度差作为开关函数,相电流平方和作为控制对象,在常规滑模控制器设计中引入模糊控制,建立模糊滑模控制的数学模型,并给出系统的结构框图。通过仿真,分析开关磁阻电机在模糊滑模控制下的各种特性。实验结果证明模糊滑模控制方法有良好的动态性能,较强的鲁棒性,在不清楚电机精确模型的情况下可有效克服转矩脉动。     

同步发电机混沌振荡的积分滑模模糊控制

针对一类不确定的非线性系统,把自适应模糊控制和积分滑模控制相结合,提出了一种新的自适应积分滑模模糊控制策略。利用模糊逻辑逼近系统中的未知非线性函数,在滑模控制中引入了积分项,消除了常规滑模控制器被跟踪信号导数已知的限制;并且为了消除外界扰动的影响,引入扰动估计器的设计方法;同时基于Lyapunov方法导出了参数的自适应律,有效地克服了系统固有的抖振问题。理论分析证明了闭环系统的稳定性和跟踪误差收敛于零。用该控制器对同步发电机混沌振荡控制系统进行仿真研究,结果表明:与常规的滑模控制器相比,该控制器具有较强的鲁棒性和较好的跟踪性能。     

Gasoline engine air filter health monitoring by second‐order sliding modes

This paper presents a novel and cheap methodology to classify healthy and clogged air filter. Air filter is an integral part of air intake system of spark ignition engine and is responsible to deliver clean air for combustion process. A clogged air filter may hamper engine power and its drivability performance. As a consequence, its health monitoring becomes mandatory. This task is accomplished by modeling the air filter effects on air flow through inlet manifold pressure by incorporating a newly introduced air filter discharge coefficient (C_af) in its dynamics. The estimation of C_af gives an idea about the health of air filter, as no sensor can be installed to measure it. A second‐order sliding mode observer is employed to estimate immeasurable C_af. Super twisting‐based sliding mode observer requires manifold pressure, engine angular speed, and load torque as input. A successful implementation has been carried out to diagnose clogged and healthy air filter of commercial vehicle engine compliant to on‐board diagnostics version‐II. This characterizes ‘ C_af’ as a clean indicator of air filter health classification. Copyright © 2012 John Wiley & Sons, Ltd.     

Decentralized adaptive backstepping stabilization of interconnected systems with input time delays in dynamic interactions

In this paper, we provide a solution to the problem by considering input time delays in dynamic interactions. Each local controller, designed simply on the basis of the model of each subsystem by using filtered transformation and standard backstepping technique, only employs local information to generate control signals. The robustness of decentralized adaptive controllers is established. It is shown that the designed decentralized adaptive backstepping controllers can globally stabilize the overall interconnected system asymptotically. The L₂ and L_∞ norms of the system outputs are also established as functions of design parameters. This implies that the transient system performance can be adjusted by choosing suitable design parameters. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive fuzzy sliding mode control of Lorenz chaotic system

By using the exponential reaching law technology, a sliding mode controller was designed for Lorenz chaotic system subject to an unknown external disturbance. On this basis, considering the unknown disturbance, an adaptive law was introduced to adaptively estimate the parameters of the disturbance bounds. Furthermore, to eliminate the chattering resulting from the discontinuous switch controller and to guarantee system transient performance, a new adaptive fuzzy sliding mode controller was designed. The results of the simulation show the effectiveness of the proposed control scheme. Translated from Journal of Harbin Institute of Technology, 2006, 38(4): 499–502 [译自: 哈尔滨工业大学学报]     

Single-input fuzzy-like moving sliding surface approach to the sliding mode control

A new approach to the sliding mode control of second-order nonlinear systems is introduced in continuous-time. A single-input fuzzy logic controller is used to continuously compute the slope of the sliding surface, with the result that the sliding surface is rotated in such a direction that tracking performance of the system under control is improved. The proposed fuzzy moving sliding surface approach with a one-dimensional rule base (FMSS-1D) reduces huge number of linguistic fuzzy rules significantly. However, it is shown that the input/output relation of the single-input fuzzy rule base is very close to the input/output relation of a straight line. Therefore, a single-input fuzzy-like moving sliding surface (FLMSS) approach using an approximate line function is then proposed. It is shown that the proposed control approaches have better tracking performance than the conventional sliding mode control with fixed sliding surface. The proposed moving sliding surface approaches are applied to balance an inverted pendulum on a cart. Computer simulations are presented to show the effectiveness of the proposed methods and to make a quantitative comparison with the classical sliding-mode controller with fixed sliding surface method existing in literature.     

Adaptive backstepping control for a class of time delay systems with nonlinear perturbations

The sliding mode control method has been extensively employed to stabilize time delay systems with nonlinear perturbations. Although the resulting closed‐loop systems have good transient and steady‐state performances, the designed controllers are dependent on the time delays. But one knows that it is difficult to obtain the precise delay time in practical systems, especially when it is time varying. In this paper, we revisit the problem and use the backstepping method to construct the state feedback controller. First, a coordinate transformation is used to obtain a cascade time delay system. Then, a linear virtual control law is designed for the first subsystem. The memoryless controller is further constructed based on adaptive method for the second subsystem with the uncertainties bounded by linear function. By choosing new Lyapunov–Krasovskii functional, we show that the system state converges to zero asymptotically. Via the proposed approach, we also discuss the case that the uncertainties are bounded by nonlinear functions. Finally, simulations are done to verify the effectiveness of the main results obtained. Copyright © 2007 John Wiley & Sons, Ltd.     

多关节机器人的反演自适应模糊滑模控制

针对二关节机器人轨迹跟踪问题,设计了一种新的反演自适应模糊滑模控制器.该方法设计了反演滑模控制器和自适应模糊控制器,通过设计合适的自适应律,采用模糊控制器在线估计不确定性上界值,实现了对建模误差和干扰的自动跟踪,削弱了抖振.利用李亚普诺夫定理证明了系统的稳定性.仿真结果表明该方法的有效性.     

一类不确定非线性系统的自适应模糊滑模控制

针对一类不确定非线性系统自适应模糊控制中,为了保证系统稳定性而附加监督控制问题,根据滑模控制原理并利用模糊系统的逼近能力,提出了一种Ⅰ型间接自适应模糊滑模控制方法。该方法取消了监督控制,用滑模控制器增加了逼近误差的自适应补偿,李雅普诺夫稳定性理论分析证明,控制系统全局稳定且跟踪误差收敛到零。将这种控制器应用到过程控制的典型对象液位控制中,仿真结果表明了该控制器的有效性和可行性。     

Adaptive motion/force tracking control of holonomic constrained mechanical systems: a unified viewpoint

This paper proposes a robust adaptive motion/force tracking controller for holonomic constrained mechanical systems with parametric uncertainties and disturbances. First, two types of well‐known holonomic systems are reformulated as a unified control model. Based on the unified control model, an adaptive scheme is then developed in the presence of pure parametric uncertainty. The proposed controller guarantees asymptotic motion and force tracking without the need of extra conditions. Next, when considering external disturbances, control gains are designed by solving a linear matrix inequality (LMI) problem to achieve prescribed robust performance criterion. Indeed, arbitrary disturbance/parametric error attenuation with respect to both motion and force errors along with control input penalty are ensured in the L₂‐gain sense. Finally, applications are carried out on a two‐link constrained robot and two planar robots transporting a common object. Numerical simulation results show the expected performances. Copyright © 2006 John Wiley & Sons, Ltd.