基于扰动补偿趋近律的非匹配离散广义准滑模控制

研究了非匹配不确定离散广义系统准滑模控制策略的综合问题.给出了具有前级状态向量的动态切换函数,使得系统能够在切换带内稳定.设计了两种带有扰动补偿的离散广义趋近律,消除了常规滑模控制策略中不确定项必须有界的限制,且不必满足匹配条件.给出了系统准滑动模态保持逐步穿越切换面的必要条件,减小了准滑动模态切换带的带宽.所设计的滑模控制器在有限时间内可达切换面,削弱了系统抖振,有效地改善了系统动态品质.最后,数值算例验证了该控制策略的可行性.     

基于拓扑切换的异构多智能体系统协同输出调节

针对拓扑切换下的异构多智能体输出调节系统,考虑当系统中部分智能体无法获取到外部系统控制状态,且系统的拓扑图随时间变换的问题,设计了一种基于分布式输出反馈状态观测器的切换控制器,给出了拓扑切换下多智能体输出调节问题可解的充分条件,该条件与控制参数和通讯拓扑有关.基于图论和矩阵分析的方法,设计了李雅普诺夫函数,并证明了系统的镇定性.最后给出了系统的Matlab仿真实验,研究结果表明,在拓扑切换条件下多智能体的输出渐近跟踪并收敛到外部系统,所设计的控制器能解决动态切换下输出反馈输出调节问题.     

带有干扰的线性时变系统变结构鲁棒控制器

对含有未知时变参数和系统干扰的单输入单输出线性时变系统,给出了一种输出跟踪变结构鲁棒控制器设计机制．系统参数只要求光滑有界,没有其它限制条件．通过引入辅助信号和带有记忆功能的正规化信号以及适当选择控制器参数,该变结构控制器能保证闭环系统所有信号有界,跟踪误差能被调整到任意小．     

T型行人流通道建模及滑模控制方法北大核心CSCD

对行人在不同通道结构中的疏散方式的研究,在优化通行效率,避免事故发生以及设计通道结构中都具有重要价值.首先,基于行人流宏观模型和质量守恒定理,建立了一个具有数个可控出入口的T型通道行人流模型.然后,以避免拥堵并且最大化整体模型通行量的控制目标,采用级联的方式,设计了一种滑模控制器,用李雅普诺夫稳定性原理证明了系统的稳定性,同时采取了边界层的方法来抑制抖振现象.最后,进行了数值仿真,结果表明,滑模控制器达到了控制目标,并且边界层方法有效地抑制了控制器的抖振.     

一类线性切换系统基于带有时滞观测器的输出反馈镇定

许多切换系统的状态是不可测或不能完全可测的,从观测器设计的角度重新考虑了带有时滞的线性切换系统的输出反馈镇定问题.主要研究了观测器带有延时,且控制器也带有切换延时的情况,最终得到了系统可镇定的充分条件.     

T型行人流通道建模及滑模控制方法

对行人在不同通道结构中的疏散方式的研究,在优化通行效率,避免事故发生以及设计通道结构中都具有重要价值.首先,基于行人流宏观模型和质量守恒定理,建立了一个具有数个可控出入口的T型通道行人流模型.然后,以避免拥堵并且最大化整体模型通行量的控制目标,采用级联的方式,设计了一种滑模控制器,用李雅普诺夫稳定性原理证明了系统的稳定性,同时采取了边界层的方法来抑制抖振现象.最后,进行了数值仿真,结果表明,滑模控制器达到了控制目标,并且边界层方法有效地抑制了控制器的抖振.     

具有不确定项的高阶非完整系统的反馈控制问题的研究

针对一类具有不确定性的高阶非完整系统,通过引入观测器,采用状态-输入转换、反推方法,设计了反馈控制器.同时为了处理初值为0的情况,提出了一种新的基于第一个子系统输出值的切换控制策略,提出的切换控制策略能有效的防止系统的状态发生有限时间逃逸现象.     

一类切换线性系统的动态输出反馈H_∞控制:LMIs方法

研究一类由任意有限多个线性子系统组成的切换系统的动态输出反馈H∞控制问题.利用共同Lyapunov函数方法和凸组合技术,给出由矩阵不等式表示的控制器存在的充分条件,并设计了相应的子控制器和切换规则.采用消元法,将该矩阵不等式转化为一组线性矩阵不等式(LMIs).最后给出一个数值仿真实例证明结论的有效性.     

鲁棒自适应仿生模糊滑模控制

针对一类非线性系统,将生物个体对外界环境的适应对策弓J入滑模控制中,在模糊滑模控制的基础上提出了仿生模糊滑模控制方法.该法利用生物随外界环境变化的主动适应性来设计控制器.在实际问题中往往出现建模误差、外界干扰等不确定因素,为了补偿模糊控制器与理想控制器的误差,增加了一个鲁棒控制器.这样使系统具有更强的鲁棒性和抗扰动性,有效避免抖振和消除误差,达到理想状态.同时,利用Lyapunov稳定性理论,证明了闭环系统的全局稳定性.最后对线性系统和倒立摆系统进行了仿真,结果表明了方法的有效性和可行性.     

鲁棒自适应仿生模糊滑模控制北大核心

针对一类非线性系统,将生物个体对外界环境的适应对策弓J入滑模控制中,在模糊滑模控制的基础上提出了仿生模糊滑模控制方法.该法利用生物随外界环境变化的主动适应性来设计控制器.在实际问题中往往出现建模误差、外界干扰等不确定因素,为了补偿模糊控制器与理想控制器的误差,增加了一个鲁棒控制器.这样使系统具有更强的鲁棒性和抗扰动性,有效避免抖振和消除误差,达到理想状态.同时,利用Lyapunov稳定性理论,证明了闭环系统的全局稳定性.最后对线性系统和倒立摆系统进行了仿真,结果表明了方法的有效性和可行性.     

Anti-synchronization of uncertain unified chaotic systems with dead-zone nonlinearity

This paper addresses chaos anti-synchronization of uncertain unified chaotic systems with dead-zone input nonlinearity. Using the sliding mode control technique and Lyapunov stability theory, a proportional–integral (PI) switching surface is proposed to ensure the stability of the closed-loop error system in sliding mode. Then a sliding mode controller (SMC) is proposed to guarantee the hitting of the switching surface even with uncertainties and the control input containing dead-zone nonlinearity. Some simulation results are included to demonstrate the effectiveness and feasibility of the proposed synchronization scheme.     

Exponential synchronization of chaotic systems subject to uncertainties in the control input

A sliding mode control technique is introduced for exponential synchronization of chaotic systems. These systems are described by a general form including matched and unmatched nonlinear functions. A new hitting-free switching surface of proportional-integral type is proposed. This type of switching surface is without the hitting process if the attraction of sliding manifold is ensured. This property makes it easy to exponentially synchronize the master-slave chaotic systems. Based on this switching surface, a robust sliding mode controller (SMC) is derived to guarantee the attraction of sliding manifold even when the system is subjected to input uncertainties. An example is included to illustrate the results developed in this paper.     

Adaptive tracking control for a class of switched uncertain nonlinear systems under a new state-dependent switching law

This paper deals with the problem of adaptive fuzzy tracking control for a class of switched uncertain nonlinear systems. Fuzzy logic systems are utilized to approximate the unknown nonlinear functions, and the adaptive backstepping and dynamic surface control techniques are adopted. First, a new state-dependent switching method is proposed. By introducing convex combination technique and designing a state-dependent switching law, only the solvability of the adaptive tracking control problem for a convex combination of the subsystems is necessary. Second, a new common Lyapunov function with switched adaptive parameters is constructed to reduce the conservatism. Third, to avoid Zeno behavior, a modified state-dependent switching law with dwell time is proposed. It is shown that under the proposed control and switching laws, all the signals of the closed-loop system are bounded and all the state tracking errors can converge to a priori accuracy, even if some subsystems are uncontrollable. Finally, the effectiveness of the proposed method is illustrated through two simulation examples.     

Adaptive stabilization of high order nonholonomic systems with strong nonlinear drifts

This paper investigates the problem of adaptive stabilization control design for a class of high order nonholonomic systems in power chained form with strong nonlinear drifts, including unmodeled dynamics, and dynamics modeled with unknown nonlinear parameters. A parameter separation technique is introduced to transform the nonlinear parameterized system into a linear-like parameterized system. Then, by the use of input-state scaling technique and adding a power integrator backstepping approach, an adaptive state feedback controller is obtained. The adaptive control based switching strategy is proposed to eliminate the phenomenon of uncontrollability. Global asymptotic regulation of the closed-loop system states and the boundedness of other signals are guaranteed. Simulation examples demonstrate the effectiveness of the proposed scheme.     

Optimal switching control of a fed-batch fermentation process

Considering the hybrid nature in fed-batch culture of glycerol biconversion to 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae, we propose a state-based switching dynamical system to describe the fermentation process. To maximize the concentration of 1,3-PD at the terminal time, an optimal switching control model subject to our proposed switching system and constraints of continuous state inequality and control function is presented. Because the number of the switchings is not known a priori, we reformulate the above optimal control problem as a two-level optimization problem. An optimization algorithm is developed to seek the optimal solution on the basis of a heuristic approach and control parametrization technique. Numerical results show that, by employing the obtained optimal control strategy, 1,3-PD concentration at the terminal time can be increased considerably.     

Fast terminal sliding mode controller design for nonlinear second‐order systems with time‐varying uncertainties

This article investigates a novel fast terminal sliding mode control approach combined with global sliding surface structure for the robust tracking control of nonlinear second‐order systems with time‐varying uncertainties. The suggested control technique is formulated based on the Lyapunov stability theory and guarantees the existence of the sliding mode around the sliding surface in a finite time. Using the new form of switching surface, the reaching phase elimination and the robustness improvement of the whole system are satisfied. Simulation results demonstrate the efficiency of the proposed technique. © 2014 Wiley Periodicals, Inc. Complexity 21: 239–244, 2015     

A sliding mode approach to robust stabilisation of Markovian jump linear time-delay systems with generally incomplete transition rates

This paper is devoted to investigating the problem of robust sliding mode control for a class of uncertain Markovian jump linear time-delay systems with generally uncertain transition rates (GUTRs). In this GUTR model, each transition rate can be completely unknown or only its estimate value is known. By making use of linear matrix inequalities technique, sufficient conditions are presented to derive the linear switching surface and guarantee the stochastic stability of sliding mode dynamics. A sliding mode control law is developed to drive the state trajectory of the closed-loop system to the specified linear switching surface in a finite-time interval in spite of the existing uncertainties, time delays and unknown transition rates. Finally, an example is presented to verify the validity of the proposed method.     

Sampled-data control of uncertain switched neutral nonlinear systems under asynchronous switching

The robust exponential stabilization for a class of the uncertain switched neutral nonlinear systems with time-varying delays based on the sampled-data control is investigated in this paper. The closed-loop system with sampled-data control is modeled as a continuous time system with a time-varying piecewise continuous control input delay. Considering the relationship between the sampling period and the dwell time of two switching instants, sampling interval with no switching and sampling interval with one switching are discussed, respectively. By Wirtinger-based inequality, Wirtinger-based double integral inequality, and free-weighting matrix technique, some delay-dependent sufficient conditions are given to guarantee the exponential stability of uncertain switched neutral nonlinear systems under asynchronous switching. In addition, sampled-data controllers can also be designed by special operations of matrices. Finally, two numerical examples are used to show the effectiveness of the approach proposed in this paper.     

Adaptive output feedback asymptotic stabilization of nonholonomic systems with uncertainties

A global adaptive output feedback control strategy is presented for a class of nonholonomic systems in generalized chained form with drift nonlinearity and unknown virtual control parameters. The purpose is to design a nonlinear output feedback switching controller such that the closed-loop system is globally asymptotically stable. By using the input-state scaling technique and an integrator back-stepping approach, an output feedback controller is given. A filter of observer gain is introduced for state and parameter estimates. Meanwhile, in order to avoid the over-parameters, a tuning function technique is utilized. A novel switching control strategy based on the output measurement of the first subsystem rather than time is used to overcome the uncontrollability of the x₀-subsystem in the origin. The proposed controller can guarantee that all the system states globally converge to the origin, while other signals maintain bounded. The numerical simulation testifies the effectiveness.