A new four-dimensional chaotic system with first Lyapunov exponent of about 22,hyperbolic curve and circular paraboloid types of equilibria and its switching synchronization by an adaptive global integral sliding mode control

This paper presents a new four-dimensional（4 D） autonomous chaotic system which has first Lyapunov exponent of about 22 and is comparatively larger than many existing three-dimensional（3 D） and 4 D chaotic systems.The proposed system exhibits hyperbolic curve and circular paraboloid types of equilibria.The system has all zero eigenvalues for a particular case of an equilibrium point.The system has various dynamical behaviors like hyperchaotic,chaotic,periodic,and quasi-periodic.The system also exhibits coexistence of attractors.Dynamical behavior of the new system is validated using circuit implementation.Further an interesting switching synchronization phenomenon is proposed for the new chaotic system.An adaptive global integral sliding mode control is designed for the switching synchronization of the proposed system.In the switching synchronization,the synchronization is shown for the switching chaotic,stable,periodic,and hybrid synchronization behaviors.Performance of the controller designed in the paper is compared with an existing controller.

Position Control of a Series Elastic Actuator Based on Global Sliding Mode Controller Design

A series elastic actuator(SEA) is a powerful device in the area of human-machine integration, but it still suffers from difficult position control issues. Therefore, in this paper,an efficient approach is proposed to solve this problem. The approach design is divided into two steps: feedback linearization(FL) and global sliding mode(GSM) controller design. The bounded analysis is presented and global asymptotic convergence is analytically proven. Simulation and experiment results illustrate the effectiveness of the proposed scheme.

Disturbance observer based time-varying sliding mode control for uncertain mechanical system

It is now well known that the time-varying sliding mode control （TVSMC） is characterized by its global robustness against matched model uncertainties and disturbances. The accurate tracking problem of the mechanical system in the presence of the parametric uncertainty and external disturbance is addressed in the TVSMC framework. Firstly, an exponential TVSMC algorithm is designed and the main features are analyzed. Especially, the control parameter is obtained by solving an optimal problem. Subsequently, the global chattering problem in TVSMC is considered. To reduce the static error resulting from the continuous TVSMC algorithm, a disturbance observer based time-varying sliding mode control （DOTVSMC） algorithm is presented. The detailed design principle and the stability of the closed-loop system under the composite controller are provided. Simulation results verify the effectiveness of the proposed algorithm.

Decentralized model reference adaptive sliding mode control based on fuzzy model

A new design scheme of decentralized model reference adaptive sliding mode controller for a class of MIMO nonlinear systems with the high-order interconnections is propcsed. The design is based on the universal approximation capability of the Takagi - Seguno （T-S） fuzzy systems. Motivated by the principle of certainty equivalenteontrol, a decentralized adaptive controller is designed to achieve the tracking objective without computafion of the T-S fuzz ymodel. The approach does not require the upper bound of the uncertainty term to be known through some adaptive estimation. By theoretical analysis, the closed-loop fuzzy control system is proven to be globally stable in the sense that all signalsinvolved are bounded, with tracking errors converging to zero. Simulation results demonstrate the effectiveness of the approach.

基于GSMC的改进自抗扰PMLSM控制

针对永磁同步直线电机(PMLSM)系统存在外界扰动等不确定性而使系统性能变差问题,提出了一种改进型全局滑模自抗扰控制方案。首先,考虑到扩张状态观测器中传统的非线性函数fal在原点附近不够平滑存在拐点会降低控制精度,引入了平滑性更好的Sigfal函数对其进行替换;其次,对于非线性状态误差反馈控制律部分,因参数多整定困难,影响了反馈控制的性能,采用全局滑模控制(GSMC)实现反馈控制,以提高反馈控制部分的动态及抗扰动性能;最后,用Lyapunov理论证明了系统稳定性,仿真结果表明该方案能够提高速度跟踪精度、保证动态性能同时提高了系统鲁棒性。

A Bio-Inspired Global Finite Time Tracking Control of Four-Rotor Test Bench System

A bio-inspired global finite time control using global fast-terminal sliding mode controller and radial basis function network is presented in this article,to address the attitude tracking control problem of the three degree-of-freedom four-rotor hover system.The proposed controller provides convergence of system states in a predetermined finite time and estimates the unmodeled dynamics of the four-rotor system.Dynamic model of the four-rotor system is derived with Newton’s force equations.The unknown dynamics of four-rotor systems are estimated using Radial basis function.The bio-inspired global fast terminal sliding mode controller is proposed to provide chattering free finite time error convergence and to provide optimal tracking of the attitude angles while being subjected to unknown dynamics.The global stability proof of the designed controller is provided on the basis of Lyapunov stability theorem.The proposed controller is validated by(i)conducting an experiment through implementing it on the laboratory-based hover system,and(ii)through simulations.Performance of the proposed control scheme is also compared with classical and intelligent controllers.The performance comparison exhibits that the designed controller has quick transient response and improved chattering free steady state performance.The proposed bioinspired global fast terminal sliding mode controller offers improved estimation and better tracking performance than the traditional controllers.In addition,the proposed controller is computationally cost effective and can be implanted on multirotor unmanned air vehicles with limited computational processing capabilities.

Robust backstepping global integral terminal sliding mode controller to enhance dynamic stability of hybrid AC/DC microgrids

In this paper,a Backstepping Global Integral Terminal Sliding Mode Controller(BGITSMC)with the view to enhancing the dynamic stability of a hybrid AC/DC microgrid has been presented.The proposed approach controls the switch-ing signals of the inverter,interlinking the DC-bus with the AC-bus in an AC/DC microgrid for a seamless interface and regulation of the output power of renewable energy sources(Solar Photovoltaic unit,PMSG-based wind farm),and Battery Energy Storage System.The proposed control approach guarantees the dynamic stability of a hybrid AC/DC microgrid by regulating the associated states of the microgrid system to their intended values.The dynamic stabil-ity of the microgrid system with the proposed control law has been proved using the Control Lyapunov Function.A simulation analysis was performed on a test hybrid AC/DC microgrid system to demonstrate the performance of the proposed control strategy in terms of maintaining power balance while the system’s operating point changed.Furthermore,the superiority of the proposed approach has been demonstrated by comparing its performance with the existing Sliding Mode Control(SMC)approach for a hybrid AC/DC microgrid.

基于干扰观测器与终端滑模的车辆纵向控制

为了消除未知干扰和不确定性对车辆纵向控制的影响,设计了基于干扰观测器和终端滑模控制的分层式车辆纵向控制系统.利用干扰观测器对系统干扰进行实时观测,实现对系统的反馈补偿,降低滑模控制的切换增益,从而抑制滑模控制的抖振.利用Lyapunov函数证明了控制系统的稳定性,并通过Carsim/Simulink进行了联合仿真试验.结果表明:在两种仿真工况条件下,控制器对参考速度跟踪效果良好,速度误差最大仅为0.22 m/s,干扰观测器对系统干扰能够准确快速估计,估计误差仅为0.003 14,切换逻辑执行器发挥良好;与传统滑模控制相比,所设计的控制器稳定性更好,抑制了滑模控制的抖振,实现了对车辆纵向速度的稳定跟踪.

音圈电机全局自适应非奇异快速终端滑模控制

为了改善音圈电机驱动系统的动态性能,课题组提出了一种全局自适应非奇异快速终端滑模控制策略。在非奇异快速终端滑模控制器的基础上,引入全局滑态因子,改善系统的瞬态响应;同时将自适应控制和非奇异快速终端滑模控制相结合,利用自适应控制可以根据系统的实时状态和外部干扰自动调整参数的特点,来减小扰动、提高系统的鲁棒性和抗干扰性;将控制律中的符号函数改为一种边界层的饱和函数来削弱振动;通过李亚普诺夫稳定性理论证明所提出的控制器的稳定性;最后,将全局自适应非奇异快速终端滑模控制与比例积分微分控制(proportional integral derivative,PID)和滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:与PID控制和滑模控制相比,所提出的全局自适应非奇异快速终端滑模控制提高了系统的动态响应速度和控制精度,有效改善了系统的动态性能。

基于改进模糊滑模控制的列车速度跟踪研究

列车运行过程具有强耦合、非线性等特征,且往往存在较大且不可观测的外界干扰,这些特性加大了列车运行控制的难度,针对列车运行速度跟踪控制问题,提出一种新的模糊滑模控制器设计方法。首先基于模糊滑模控制,引入全局快速终端滑模控制,使系统在有限时间内达到稳态;然后构造以李亚普洛夫函数导数的绝对值为补偿的自适应干扰估计项,对外界干扰进行准确估计,进而提出一种双层递阶指数趋近全局快速终端模糊滑模控制器,并且引入指数趋近率来调节滑模面的动态品质,该控制器能快速收敛到稳定状态,且有效地消除了控制器的抖振情况;最后通过仿真算例验证了所提方法的有效性,且提高了列车运行控制系统性能。

基于全局快速终端滑模的6-PSS并联运动模拟器轨迹跟踪控制研究

针对6-PSS并联运动模拟器动力学模型中的不确定性和时变扰动,提出了一种基于全局快速终端滑模的鲁棒控制策略。首先,运用虚功原理建立了该机构的动力学模型(该动力学模型表明6-PSS并联机构是一个具有非线性和强耦合特性的多变量系统),对动力学模型进行了离线处理,使其反映出机构真实动力学特性,并满足设备实时计算能力的要求;然后,基于简化后的动力学模型设计了一种全局快速终端滑模控制器(GFTSMC),设计李雅普诺夫(Lyapunov)函数对控制律进行了分析,证明了控制器的稳定性;最后,将控制策略应用于6-PSS并联运动模拟器轨迹跟踪控制,并将其与PD前馈控制及传统滑模控制(SMC)进行了对比实验。研究结果表明:GFTSMC相对于PD和SMC的平均误差分别下降了82.92%和18.88%,标准差分别下降了80.03%和41.73%,且能够起到抑制抖振的效果,是6-PSS并联运动模拟器的一种有效且实用的鲁棒控制方案。该研究结果可为6-PSS并联运动模拟器控制及工程应用提供理论依据。

固定翼UAV路径跟踪的全局稳定积分滑模S面控制

针对固定翼无人机的三维路径跟踪控制问题,设计了一种基于全局稳定积分滑模S面模型的内外环控制器。控制器外环采用全局稳定积分滑模控制,内环采用S面控制。设计控制器外环的全局稳定积分滑模控制律,并采用Lyapunov理论证明所设计控制律的稳定性。对内环的指令信号设计S面控制器,考虑到S面控制器中求导的复杂性,引入二阶微分器,解决内环中导数存在积分爆炸的问题。半物理仿真试验结果表明,提出的控制器能精确跟踪期望路径,具有良好的控制性能和抗干扰性能。

基于三阶超螺旋扰动观测器的PMLSM全局自适应滑模控制

针对永磁直线同步电机的位置跟踪精确度易受外部扰动、参数变化等不确定性因素影响的问题,提出全局自适应滑模控制器与三阶超螺旋扰动观测器相结合的复合控制策略。首先,为了解决全局滑模控制存在的抖振问题,根据自适应趋近律设计全局自适应滑模控制器。自适应趋近律可以根据系统状态变量的变化过程实时调整开关增益的大小,从而提高系统的响应速度并减小抖振。然后,为了提高系统的跟踪精确度以及抗干扰能力,设计三阶超螺旋扰动观测器,利用扰动观测器观测系统中无法精确测量的扰动以及存在的不确定项,实现对系统的前馈补偿。最后,进行仿真与实验验证。仿真与实验结果表明,与全局滑模控制相比,所提方法能有效提高系统的响应速度和跟踪精确度,使系统具有良好的稳态性能和动态性能。

非线性ABS系统全局滑模控制律设计

传统的ABS系统等速趋近律滑模控制器存在滑移率抖振和鲁棒性差的问题,本研究提出了一种改进的指数趋近律,即通过增加自然对数函数项,使系统的滑模运动在制动过程开始时即位于滑模面或贴近滑模面。应用Lyapunov稳定性判据证明了新设计控制器的稳定性。仿真验证结果表明,所提出的非线性全局滑模控制方案,其车轮滑移率保持在理想值附近,消除了抖振现象,提高了控制系统的鲁棒性和车辆的制动性能。

基于双滑模控制器的开关磁阻电机调速策略

针对开关磁阻电机(switched reluctance motor,SRM)传统滑模控制方法响应速度慢、抖振大且鲁棒性差的问题,该文提出一种基于双滑模控制器的开关磁阻电机调速策略。首先,设计全局积分滑模速度控制器(global integral sliding model speed controller,GISMSC),消除系统到达滑模面的过程,提高响应速度和鲁棒性,并通过改进趋近律来减小滑模抖振;其次,设计扰动滑模观测器(disturbance sliding mode observer,DSMO),对负载和未知扰动进行观测,并前馈补偿至全局积分滑模速度控制器中,进而复合构成双滑模速度控制器,并将其作为速度外环与模型预测控制(model predictive control,MPC)相结合,减小转矩脉动的同时提升其调速性能;最后,仿真和实验考虑到转速和负载突变以及电机参数失配等情况,结果表明,所提方法不仅提高了系统调速性能,减小了转矩脉动,而且克服了电机内部参数变化和外部扰动的影响,使系统具备更强鲁棒性。

电网机械终端防跌落抖动的滑膜控制方法研究

由于自动兼容式电网的结构复杂,机械终端轨迹到达滑动模态面后难以严格沿着滑动模态面向平衡点滑动,导致电压和功率突变跌落而产生抖动。对此,提出自动兼容式电网机械终端防跌落抖动的滑膜控制方法。构建机械终端数学模型,分析产生跌落抖动问题的原因。提出基于扩张观测器的滑膜控制方法,设计扩张观测器,以获取机械终端系统内部扰动信息。将观测结果用作电流前馈补偿,以优化抗干扰性。结合滑膜控制方法设计滑膜控制器,通过该控制器实现自动兼容式电网机械终端滑膜控制。试验结果表明,该方法的电流功率突变动态波动情况平稳,电网电压跌落85%后恢复至正常电压的速度较快。该方法缓解了跌落抖动程度,有效提高了动态响应波动稳定性,并促进了配电网的发展。

线控制动系统主缸液压力滑模控制鲁棒性分析

针对一种全解耦式线控液压制动系统制动主缸液压力控制过程中,易受系统参数不确定性和外界摄动量等因素的干扰,从而造成制动主缸液压力控制过程中出现振荡、爬行等问题,提出了一种综合考虑系统不利因素影响的主缸液压力全局快速滑模鲁棒控制算法。通过对制动主缸动力学模型的简化,建立了含有干扰项的主缸液压力控制参考模型,并在此基础上设计了鲁棒控制律和主缸液压力滑模控制器;此外,定义了Lyapunov函数对制动压力控制系统滑模到达时间、稳定性和收敛性进行分析。通过MATLAB/Simulink、AMESim联合仿真,对该线控制动主缸液压力控制策略进行验证和评价,结果表明所提出的液压力控制策略具有很好的鲁棒性和稳定性,并能精确跟踪期望压力,且响应迅速。

Decentralized direct adaptive neural network control for a class of interconnected systems

The problem of direct adaptive neural network control for a class of large-scale systems with unknown function control gains and the high-order interconneetions is studied in this paper. Based on the principle of sliding mode control and the approximation capability of multilayer neural networks, a design scheme of decentralized di- rect adaptive sliding mode controller is proposed. The plant dynamic uncertainty and modeling errors are adaptively compensated by adjusted the weights and sliding mode gains on-line for each subsystem using only local informa- tion. According to the Lyapunov method, the closed-loop adaptive control system is proven to be globally stable, with tracking errors converging to a neighborhood of zero. Simulation results demonstrate the effectiveness of the proposed approach.

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.