可控励磁直线同步电动机的全局积分Terminal滑模控制

为提高可控励磁直线磁悬浮同步电动机进给系统的快速性与鲁棒性,提出全局积分Terminal滑模控制策略.构造新型的全局积分Terminal滑模面,对系统状态任意初值可在有限时间内收敛到零点,在趋近律中引入衰减因子,可减小系统抖振;在构造滑模面和趋近律的基础上设计全局积分Terminal滑模速度控制器;为进一步削弱滑模控制的抖振,减小切换增益,用径向基函数神经网络设计扰动观测器,并对扰动进行前馈补偿控制.仿真结果表明全局积分Terminal滑模控制策略能够明显改善系统的动态性能,缩短误差的收敛时间,提高系统抑制扰动的能力,削弱系统的抖振,增强系统的鲁棒性.     

自适应模糊全局快速Terminal滑模控制方法

提出了一种自适应模糊全局快速Terminal滑模控制方法,在参数不确定性和外干扰情况下,为解决系统的非线性不确定性提供了一种新途径。与传统模糊Terminal滑模控制相比,通过采用模糊逻辑系统来逼近未知系统函数和开关项;鲁棒自适应律用来减小逼近误差,从而有效降低抖振;证明了该控制方案的稳定性,并将该方案应用在倒立摆系统中。仿真结果验证了该方案的有效性。     

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.     

不确定欠驱动系统的高阶自适应Super-Twisting滑模控制

为实现一类不确定欠驱动系统在未知干扰情况下的鲁棒控制,针对传统滑模控制中存在的抖振问题,提出一种基于二次型Lyapunov函数的二阶Super-Twisting自适应滑模控制策略.首先,控制器的不连续项采用二阶Super-Twisting算法,将不连续控制作用在滑模量的二阶导数.然后,针对滑模面受不确定干扰影响的情况,为调节参数设计一种自适应律方法,该方法不受传统二阶滑模控制中干扰项的一阶导数边界已知的条件限制,保证滑模面在有干扰情况下的收敛,削弱控制器输入的抖振现象.最后,以两轮自平衡车为实验对象验证该方法,并与传统滑模及普通二阶滑模方法做仿真对比.仿真结果表明文中所提的二阶自适应滑模控制方法在控制效果和降低抖振方面表现更优.     

一类3阶非线性系统的非奇异终端滑模控制

针对传统非奇异终端滑模控制方法不适用于3阶系统的问题,提出一类具有不确定和外干扰的3阶非线性系统的新型非奇异终端滑模控制方法.该方案首先结合backstepping控制中的动态面方法和传统2阶非奇异终端滑模控制构造非奇异3阶终端滑模面,首次提出采用高阶滑模微分器估计值代替控制器中的负指数项.采用非线性干扰观测器任意精度地估计不确定和干扰,设计控制器中的补偿项.采用终端吸引子函数做趋近律避免抖振的同时能保证有限时间趋近滑模面.基于有限时间稳定李雅普诺夫定理证明了被控状态将在有限时间内收敛到任意小的闭球内.所提出方案快于传统的递阶线性滑模控制和其他非奇异终端滑模控制.仿真中与其他滑模控制方案对比,总误差减小18%以上,超调及收敛时间也显著下降.     

非匹配离散系统无抖振鲁棒准滑模控制

研究离散准滑动模态的鲁棒性恢复和抖振削弱问题。针对一类同时含有匹配建模误差和非匹配外界干扰不确定离散系统,设计一种基于解耦干扰补偿器的鲁棒准滑模控制方案。为保证系统的鲁棒性,针对非匹配外界干扰设计一种改进的解耦干扰补偿器,估计误差有界收敛。通过引入幂次函数设计鲁棒离散准滑模控制器,消除系统抖振,给出切换函数准滑模带,并证明了闭环系统离散准滑动模态的稳定可达性。最后通过仿真验证了所提出控制方案的有效性。     

非线性系统的反演自适应动态滑模控制

为削弱非线性系统中由滑模控制引起的抖振现象,提出自适应动态滑模控制方案.动态滑模方法是通过设计新的切换函数或将常规滑模变结构控制中的切换函数s通过微分环节构成新的切换函数,该切换函数与系统控制输入的一阶或高阶导数有关,可将不连续项转移到控制的一阶或高阶导数中去,得到在时间上本质连续的动态滑模控制律.该方案利用自适应技术和反演法,设计动态滑模控制器,有效地削弱了系统的抖振.最后仿真结果证明了该方案是正确的.     

基于干扰观测器的航天器非奇异终端二阶滑模控制

为了消除干扰力矩和结构不确定性对卫星姿态控制性能的影响,本文提出了一种基于新型干扰观测器的非奇异终端二阶滑模控制方法.首先,文章设计了一种基于跟踪微分器的干扰观测器,来对卫星系统中的不确定项进行估计,利用估计值进行补偿,并保证估计误差在有限时间内收敛.在此基础上,文章设计一个非奇异终端滑模面,当系统到达滑模面时,姿态误差可以在有限时间内收敛,并利用二阶滑模趋近律设计控制器,保证系统在有限时间到达滑模面.在干扰观测器误差未完全收敛时,滑模控制器可以对存在的扰动进一步抑制,实现姿态跟踪系统的有限时间稳定,并通过李雅普诺夫方法严格证明了其稳定性.最后,仿真结果表明,干扰估计值误差可以在有限时间内收敛,证明了该控制方法对存在的干扰是具有较好的鲁棒性.     

一类新的二阶滑模控制方法及其在倒立摆控制中的应用

二阶滑模作为高阶滑模的特殊情形, 不仅具有传统滑模鲁棒性强、对外界干扰不敏感的特点, 而且能够有效地消弱传统一阶滑模中存在的"抖振"现象. 本文设计了一种新的二阶滑模控制算法. 该算法的优点是假设不确定性是由非负函数限制而不是由常数限定. 因此, 该算法在实际应用中具有更广的应用范围. 此外, 算法中的加幂积分技术保证了系统在有限时间内稳定, 而不是传统二阶滑模中普遍存在的有限时间收敛, 并给出了严格的数学证明. 最后, 在倒立摆控制中的应用验证了该算法的有效性.     

基于干扰观测器的一类不确定非线性系统自适应二阶动态terminal滑模控制

针对一类不确定非线性系统的跟踪控制问题,在考虑建模误差、参数不确定和外部干扰情况下,以其拥有良好的跟踪性能以及强鲁棒性为目标,提出基于回归扰动模糊神经网络干扰观测器(recurrent perturbation fuzzy neural networks disturbance observer,RPFNNDO)的鲁棒自适应二阶动态terminal滑模控制策略.将回归网络、模糊神经网络和sine-cosine扰动函数各自优势相结合,给出一种回归扰动模糊神经网络结构,提出RPFNNDO设计方法,保证干扰估计准确性;构造基于带有指数函数滑模面的二阶快速terminal滑模面,给出其控制器设计过程,避免了滑模到达阶段、传统滑模的抖振问题,采用具有指数收敛的鲁棒项抑制干扰估计误差对系统跟踪性能的影响,利用Lyapunov理论证明闭环系统的稳定性;将该方法应用于混沌陀螺系统同步控制仿真实验,结果表明所提方法的有效性.     

Chattering free full-order sliding-mode control

In conventional sliding-mode control systems, the sliding-mode motion is of reduced order. Two main problems hindering the application of the sliding-mode control are the singularity in terminal sliding-mode control systems and the chattering in both the conventional linear sliding-mode and the terminal sliding-mode control systems. This paper proposes a chattering-free full-order terminal-sliding-mode control scheme. Since the derivatives of terms with fractional powers do not appear in the control law, the control singularities are avoided. A continuous control strategy is developed to achieve the chattering free sliding-mode control. During the ideal sliding-mode motion, the systems behave as a desirable full-order dynamics rather than a desirable reduced-order dynamics. A systematic design method of full-order sliding-mode control for nonlinear systems is presented, which allows both the chattering and singularity problems to be resolved. Simulations validate the proposed chattering free full-order sliding-mode control.     

一种基于自适应2阶终端滑模控制算法的理论和实验研究

针对一类非线性多变量被控对象的控制问题,设计了一种基于自适应2阶终端滑模的自主控制方法．与传统滑模控制方法相比,该控制方案保留了其结构简单、鲁棒性强的优点,并有效削弱了传统滑模控制引发的抖振问题．利用基于李亚普诺夫的分析方法进行闭环系统的稳定性分析,确保了闭环系统的稳定性以及控制误差有限时间收敛．通过在3自由度控制实验平台上进行姿态镇定和跟踪实验,表明本文所提出的控制方法具有良好的姿态控制效果.     

永磁同步电机伺服系统的自适应模糊滑模控制

针对永磁同步电机伺服系统的跟踪控制问题,提出了一种基于扰动观测器的自适应模糊滑模控制方法.通过扰动观测器估计等效扰动,改善了系统的动态性能和稳态性能,并且只需要等效扰动的变化有界,而不是为零,放宽了要求;根据模糊控制原理引入3条模糊规则,在保证滑模条件的前提下有效地削弱了抖振;采用自适应策略估计模糊系统参数的最优值,简化了控制器的设计.实验结果表明,与常规自适应模糊滑模控制相比,本文提出的控制方法不仅能够有效地减小跟踪误差,而且能够改善参数估计过程,保证了参数估计的有界性.     

Design of Cascade Adaptive Fuzzy Sliding-Mode Control for Nonlinear Two-Axis Inverted-Pendulum Servomechanism

Because the dynamic characteristic of a two-axis inverted-pendulum servomechanism is a nonlinear underactuated system, it is difficult to design a suitable control scheme that realizes real-time stabilization and accurate tracking control simultaneously. In general, the techniques developed for fully actuated systems cannot be used directly in underactuated systems. In this study, a cascade adaptive fuzzy sliding-mode control (AFSMC) scheme including inner and outer control loops is investigated for the stabilizing and tracking control of a nonlinear two-axis inverted-pendulum servomechanism. The aim of the inner control loop is to design an AFSMC law with fuzzy estimators so that the stick-angle vector can fit the stick-angle command vector derived from the stick-angle reference model. In the outer loop, the reference signal vector is designed via a fuzzy path-planning scheme so that the cart position vector tracks the cart-position command vector and the stick-angle tracking-error vector converges to zero simultaneously. All adaptive algorithms in the cascade AFSMC system are derived in the sense of Lyapunov stability analysis, so that system stability can be guaranteed in the entire closed-loop system. The effectiveness of the proposed control strategy is verified by numerical simulations and experimental results, and the superiority of the cascade AFSMC system is indicated in comparison with a cascade sliding-mode control system.      

MIMO adaptive fuzzy terminal sliding-mode controller for robotic manipulators

A new design approach of a multiple-input-multiple-output (MIMO) adaptive fuzzy terminal sliding-mode controller (AFTSMC) for robotic manipulators is described in this article. A terminal sliding-mode controller (TSMC) can drive system tracking error to converge to zero in finite time. The AFTSMC, incorporating the fuzzy logic controller (FLC), the TSMC, and an adaptive scheme, is designed to retain the advantages of the TSMC while reducing the chattering. The adaptive law is designed on the basis of the Lyapunov stability criterion. The self-tuning parameters are adapted online to improve the performance of the fuzzy terminal sliding-mode controller (FTSMC). Thus, it does not require detailed system parameters for the presented AFTSMC. The simulation results demonstrate that the MIMO AFTSMC can provide a reasonable tracking performance.     

Dynamic structure adaptive neural fuzzy control for MIMO uncertain nonlinear systems

This paper proposes a novel dynamic structure neural fuzzy network (DSNFN) to address the adaptive tracking problems of multiple-input-multiple-output (MIMO) uncertain nonlinear systems. The proposed control scheme uses a four-layer neural fuzzy network (NFN) to estimate system uncertainties online. The main feature of this DSNFN is that it can either increase or decrease the number of fuzzy rules over time based on tracking errors. Projection-type adaptation laws for the network parameters are derived from the Lyapunov synthesis approach to ensure network convergence and stable control. A hybrid control scheme that combines the sliding-mode control and the adaptive bound estimation control with different weights improves system performance by suppressing the influence of external disturbances and approximation errors. As the employment of the DSNFN, high-quality tracking performance could be achieved in the system. Furthermore, the trained network avoids the problems of overfitting and underfitting. Simulations performed on a two-link robot manipulator demonstrate the effectiveness of the proposed control scheme.     

On-line constructive fuzzy sliding-mode control for voice coil motors

In this paper, a voice coil motor (VCM) featuring fast dynamic performance and high position repeatability is developed. To achieve robust VCM control performance under different operating conditions, an on-line constructive fuzzy sliding-mode control (OCFSC) system, which comprises of a main controller and an exponential compensator, is proposed. In the main controller, a fuzzy observer is used to on-line approximate the unknown nonlinear term in the system dynamics with on-line structure learning and parameter learning using a gradient descent algorithm. According to the structure learning mechanism, the fuzzy observer can either increase or decrease the number of fuzzy rules based on tracking performance. The exponential compensator is applied to ensure the system stability with a nonlinear exponential reaching law. Thus, the chattering signal can be alleviated and the convergence of tracking error can be speed up. Finally, the experimental results show that not only the OCFSC system can achieve good position tracking accuracy but also the structure learning ability enables the fuzzy observer to evolve its structure on-line.     

基于云模型的船舶航迹跟踪滑模控制

为解决船舶路径跟踪控制中存在的非线性问题,引入滑模控制实现船舶的轨迹跟踪。采用云模型与指数趋近律结合的方法,设计基于云模型的轨迹跟踪智能滑模控制器,以减少滑模控制中的抖振。仿真结果表明,通过云模型的不确定性推理,智能滑模控制器能够动态调整滑模控制的趋近速度,抑制抖振的产生,船舶动态轨迹跟踪性能良好,能够精确控制航迹。     

Super-twisting second-order sliding mode control for a synchronous reluctance motor

This article presents the design and implementation of a super-twisting second-order sliding-mode controller (SOSMC) for a synchronous reluctance motor. Second-order sliding-mode control is an effective tool for the control of uncertain nonlinear systems since it overcomes the main drawbacks of the classical sliding-mode control, i.e., the large control effort and the chattering phenomenon. Its real implementation implies simple control laws, and ensures an improvement in the sliding accuracy with respect to conventional sliding-mode control. This article proposes a novel scheme that is based on the technique of super-twisting second-order sliding-mode control. First, SOSMC is derived mathematically, and then the performance of the proposed method is verified by simulations. The proposed SOSMC shows robustness for variations in the motor parameters and an improvement in the chattering phenomenon.     

推进器饱和约束的水面无人艇固定时间精准跟踪控制

针对复杂扰动、完全未知系统动态以及推进器饱和约束的水面无人艇高精度跟踪控制问题,提出一种基于固定时间非奇异终端滑模的无模型固定时间精准跟踪控制(MFPTC)方案.首先,设计有限时间集总观测器,精确重构和补偿集总未知项;其次,引入自适应辅助系统消除推进器饱和特性,使得MFPTC方案在饱和约束下实现期望时间内对预定轨迹的精准跟踪;进而,基于反正切函数构造固定时间幂次趋近律,加快滑模变量收敛速度且有效削弱控制抖振;最后,采用CyberShip Ⅱ实验模型进行仿真研究,结果验证所提出MFPTC方案的有效性与优越性.