Super-Twisting Control of the Duffing-Holmes Chaotic System

In this paper, a super twisting controller (STC) is designed to control the chaotic behavior of the Duffing-Holmes system in stabilization and tracking cases. Due to lack of availability of the performance evaluation of STC in controlling Duffing-Holmes system, this paper aims to test the performance of STC in controlling Duffing-Holmes system. In order to achieve this control design, a modification of the conventional super twisting algorithm is adapted. Numerical simulations showed that the modified STC had high performance and ability to ensure robustness with respect to bounded external disturbances.

Revised barrier function-based adaptive finite-and fixed-time convergence super-twisting control

This paper presents an adaptive gain,finite-and fixedtime convergence super-twisting-like algorithm based on a revised barrier function,which is robust to perturbations with unknown bounds.It is shown that this algorithm can ensure a finite-and fixed-time convergence of the sliding variable to the equilibrium,no matter what the initial conditions of the system states are,and maintain it there in a predefined vicinity of the origin without violation.Also,the proposed method avoids the problem of overestimation of the control gain that exists in the current fixed-time adaptive control.Moreover,it shows that the revised barrier function can effectively reduce the computation load by obviating the need of increasing the magnitude of sampling step compared with the conventional barrier function.This feature will be beneficial when the algorithm is implemented in practice.After that,the estimation of the fixed convergence time of the proposed method is derived and the impractical requirement of the preceding fixed-time adaptive control that the adaptive gains must be large enough to engender the sliding mode at time t=0 is discarded.Finally,the outperformance of the proposed method over the existing counterpart method is demonstrated with a numerical simulation.

基于Super-Twisting滑模S面的无人机路径跟踪控制

针对小型固定翼无人机在执行任务时跟踪精度低以及容易受外界风影响的问题,设计基于Super-Twisting滑模S面(STSM S-Plane)的路径跟踪控制器,同时采用内外双环控制模式。外环即速度环采用Super-Twisting滑模控制,内环即姿态环采用S面控制。考虑到S面控制求导易导致积分爆炸的问题引入了二阶微分器,并对外界风组成进行建模研究。最后通过空间特殊曲线来验证所设计算法的控制性能。仿真结果表明,所设计的算法可以实现固定翼无人机对期望路径的精确跟踪,并具有良好的鲁棒性和抗干扰性能。

基于改进Super-Twisting算法和电流预测的PMSM调速控制

针对永磁同步电机传统PI控制器存在响应速度慢、控制精度低、鲁棒性差等问题,该文提出一种改进调速控制方案。首先,将全局快速积分型终端滑模理论与广义Super-Twisting算法相结合,基于Anti-Windup原理设计改进广义Super-Twisting积分终端滑模速度控制器,并采用新型分段指数函数优化控制律;其次,设计改进扩展扰动观测器对系统未知扰动进行前馈补偿;最后,在电流环引入无差拍电流预测控制器,进一步改善系统的动态响应。仿真结果表明,所提出的改进控制方案能够有效提高调速系统的动态控制性能、控制精度和鲁棒性。

基于改进型Super-twisting的双馈感应发电机直接功率控制

为提高双馈感应发电机(DFIG)直接功率控制的鲁棒性和抗干扰能力,提出一种改进型超螺旋滑模(STSMC)的直接功率控制(DPC)。首先,建立参数摄动下的DFIG最大功率捕获模型和定子磁场定向的双馈感应发电机模型;然后,将非奇异快速终端滑模面(NFTSM)与一种改进型超螺旋(Super-twisting)优化算法结合,设计DFIG直接功率控制器(IST-NFTSMC)。其中所设计的非奇异滑模面能有效避免传统滑模控制(SMC)的奇异现象,且改进超螺旋控制律能有效削弱NFTSMC抖振,提高功率控制精度;最后,通过仿真和实验,与PI控制和传统SMC控制相比,该控制能削弱DFIG功率与电流抖振问题,加快其收敛速度,提高DFIG直接功率控制稳态精度。

基于自适应Super-twisting算法的永磁同步电机驱动控制

在永磁同步电机调速系统中,良好的速度控制器要同时兼顾跟踪性能及抗干扰性能,非线性控制具有快速响应及强鲁棒性的优点,适用于速度控制器的设计,但传统滑模控制存在着严重的抖振问题。自适应Super-twisting算法属于二阶滑模,能将相轨迹的状态量以级数的形式收敛到原点,又能在线调整控制器的增益,因此能有效削弱抖振现象。采用自适应Super-twisting算法来设计速度控制器,并通过李雅普诺夫函数给出其稳定性证明。试验结果表明,所设计的控制器具有良好的跟踪性能及抗干扰性能,同时能减小电流的纹波,达到削弱抖振的目的。

Terminal sliding mode control based on super-twisting algorithm

An improved non-singular terminal sliding mode control based on the super-twisting algorithm is proposed for a class of second-order uncertain nonlinear systems. This method can effectively avoid the singularity problem and obviously reduce the chattering phenomenon. The stability of the proposed procedure is proven to be finite-time convergence using the Lyapunov theory against uncertain unmodeled dynamic and external disturbances. An example is given to show the proposed improved non-singular terminal sliding mode control (SMC) law effectively. © 1990-2011 Beijing Institute of Aerospace Information.

Cooperative guidance law based on super-twisting observer for target maneuvering

To solve the problem that multiple missiles should simultaneously attack unmeasurable maneuvering targets,a guidance law with temporal consistency constraint based on the super-twisting observer is proposed.Firstly,the relative motion equations between multiple missiles and targets are established,and the topological model among multiple agents is considered.Secondly,based on the temporal consistency constraint,a cooperative guidance law for simultaneous arrival with finite-time convergence is derived.Finally,the unknown target maneuver-ing is regarded as bounded interference.Based on the second-order sliding mode theory,a super-twisting sliding mode observer is devised to observe and track the bounded interfer-ence,and the stability of the observer is proved.Compared with the existing research,this approach only needs to obtain the sliding mode variable which simplifies the design process.The simulation results show that the designed cooperative guidance law for maneuvering targets achieves the expected effect.It ensures successful cooperative attacks,even when confronted with strong maneuvering targets.

大长径比远程制导火箭弹自适应Super-twisting控制方法

针对具有轻质薄壳结构的大长径比远程制导火箭弹刚体-弹性体耦合动力学控制难题,提出了一种自适应Super-twisting控制方法。首先,将大长径比远程制导火箭弹的弹性模态与外部干扰项视为归一化扰动,建立了考虑参数、模型不确定性的刚体-弹性体耦合动力学模型。针对外部扰动难以实时精准获取的问题,设计了有限时间收敛干扰观测器,能够在大范围气动参数摄动情形下对远程制导火箭弹外部扰动进行实时精准估计。为提高系统鲁棒性,设计了基于Super-twisting算法的自适应有限时间控制方法,使系统能根据状态误差自动调节控制参数,在削弱高频抖振的同时有效提高抗干扰能力。仿真结果表明:所提控制方法在弹体±15%气动参数摄动的条件下,由平飞状态转变为跟踪幅值为10的正弦弹道倾角指令时,实现3.2 s内弹道倾角跟踪误差收敛至0.002°,可实现远程制导火箭弹姿态平稳跟踪控制弹道倾角指令。

Sliding mode fault tolerant consensus control for multi-agent systems based on super-twisting observer

The fault-tolerant consensus problem for leader-following nonlinear multi-agent systems with actuator faults is mainly investigated.A new super-twisting sliding mode observer is constructed to estimate the velocity and undetectable fault information simultaneously.The time-varying gain is introduced to solve the initial error problem and peak value problem,which makes the observation more accurate and faster.Then,based on the estimated results,an improved sliding mode fault-tolerant consensus control algorithm is designed to compensate the actuator faults.The protocol can guarantee the finite-time consensus control of multi-agent systems and suppress chattering.Finally,the effectiveness and the superiority of the observer and control algorithm are proved by some simulation examples of the multi-aircraft system.

Advanced Functional Electromagnetic Shielding Materials:A Review Based on Micro‑Nano Structure Interface Control of Biomass Cell Walls

Research efforts on electromagnetic interference(EMI)shielding materials have begun to converge on green and sustainable biomass materials.These materials offer numerous advantages such as being lightweight,porous,and hierarchical.Due to their porous nature,interfacial compatibility,and electrical conductivity,biomass materials hold significant potential as EMI shielding materials.Despite concerted efforts on the EMI shielding of biomass materials have been reported,this research area is still relatively new compared to traditional EMI shielding materials.In particular,a more comprehensive study and summary of the factors influencing biomass EMI shielding materials including the pore structure adjustment,preparation process,and micro-control would be valuable.The preparation methods and characteristics of wood,bamboo,cellulose and lignin in EMI shielding field are critically discussed in this paper,and similar biomass EMI materials are summarized and analyzed.The composite methods and fillers of various biomass materials were reviewed.this paper also highlights the mechanism of EMI shielding as well as existing prospects and challenges for development trends in this field.

Impedance learning adaptive super-twisting control of a robotic exoskeleton for physical human-robot interaction

This study addresses two issues about the interaction of the upper limb rehabilitation robot with individuals who have disabilities.The first step is to estimate the human's target position(also known as TPH).The second step is to develop a robust adaptive impedance control mechanism.A novel Non-singular Terminal Sliding Mode Control combined with an adaptive super-twisting controller is being developed to achieve this goal.This combination's purpose is to provide high reliability,continuous performance tracking of the system's trajectories.The proposed adaptive control strategy reduces matched dynamic uncertainty while also lowering chattering,which is the sliding mode's most glaring issue.The proposed TPH is coupled with adaptive impedance control with the use of a Radial Basis Function Neural Network,which allows a robotic exoskeleton to simply track the desired impedance model.To validate the approach in real-time,an exoskeleton robot was deployed in controlled experimental circumstances.A comparison study has been set up to show how the adaptive impedance approach proposed is better than other traditional controllers.

Encoderless Five-phase PMa-SynRM Drive System Based on Robust Torque-speed Estimator with Super-twisting Sliding Mode Control

In this paper,a robust torque speed estimator(RTSE)for linear parameter changing(LPC)system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor(5-phase PMa-SynRM).This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem,as the feedback speed information is obtained directly from the virtual sensor.In addition,this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation.The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis.Furthermore,for improving the 5-phase PMa-SynRM performance,five super-twisting sliding mode controllers(ST-SMCs)are employed with providing a robust response without the impacts of high chattering problem.A super-twisting sliding mode speed controller(ST-SMSC)is employed for controlling the PMa-SynRM rotor speed,and four super-twisting sliding mode current controllers(ST-SMCCs)are employed for controlling the 5-phase PMa-SynRM currents.The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance,parameters variations,single open-phase fault,and adjacent two-phase open circuit fault conditions.

永磁同步电机的自适应Super-Twisting滑模直接转矩控制

针对永磁同步电动机直接转矩控制存在超调和转矩脉动大的问题,提出一种自适应的Super-Twisting滑模控制策略。首先,采用Super-Twisting滑模控制代替传统的滞环比较控制方式,来设计磁链控制器和转矩控制器;其次,在Super-Twisting滑模控制的基础上作出进一步改进,利用双曲正切函数取代符号函数,并在Super-Twisting滑模控制中的连续部分引入一个自适应因子,构成新的自适应Super-Twisting滑模控制策略;最后,使用MATLAB/Simulink软件搭建模型,对永磁同步电动机直接转矩控制系统进行仿真实验。结果表明,提出的改进Super-Twisting滑模控制器,在不同实验条件下的直接转矩控制系统中实现了无超调控制,转矩脉动值仅为0.2 N·m,减小了约39%。

Passive activity enhances residual control ability in patients with complete spinal cord injury

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases.However,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in vivo.Therefore,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke.Matrix metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ischemia.Herein,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel PA-TIMP-QK.PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro.The results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor function.These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

电机转速环节Super-Twisting算法二阶滑模控制律设计与研究

针对电机转速环节,研究了以Super-Twisting算法(STA)为基础的转速闭环二阶滑模控制律设计方法,无需对转速求导或求解转速极值。利用Lyapunov函数证明了系统的稳定性,并分析了系统中比例滑模项对系统收敛的稳定性和快速性的影响,以及不同类型比例滑模项的共同点与区别。仿真结果表明,在STA基础上人为增加比例滑模项可以提高系统的收敛速度,而不受系统工作状态影响,并且不改变系统的STA二阶滑模特性。由于各种电机都具有统一的转子运动方程,因此,研究结果对各种电机的转速环节二阶滑模闭环控制具有通用性。

感应电机Super-twisting算法定子磁链观测器设计

为了提高感应电机定子磁链的观测精确度,提出了一种基于Super-twisting算法的磁链观测方法,设计了定子磁链观测器,并应用到感应电机直接转矩控制中。依据滑模变结构控制的鲁棒性特点来抑制多输入多输出定子磁链观测器系统中的扰动。利用Super-twisting算法所需信息少的优点,设计了简单的控制律,从而更适合于实际工程应用。在对观测器稳定性进行分析时,将转速和耦合量看作扰动来处理,并给出了系统一致渐近稳定的充分条件。与常规电压模型法相比,基于Super-twisting算法的定子磁链估算值更加准确,且对电机定子电阻参数变化具有更强的鲁棒性。仿真和实验结果验证了该方法的有效性。

一种鲁棒高阶滑模Super-Twisting算法的全桥逆变器

利用高阶滑模super-twisting算法设计一种全桥逆变电路的控制器。该算法的核心思想是将离散控制律转移至更高阶的滑模面,从本质上消除一介滑模的抖颤影响。为了验证算法的可行性和有效性,利用MATLAB仿真软件对控制系统进行了对比实验,结果表明:1)在稳态性能下,相比于典型PI控制高阶滑模控制具有更好的跟踪效果。2)在输入和负载的扰动情况下,高阶滑模控制显示出强鲁棒性,对输入和负载的扰动不敏感。

基于U模型的非线性系统Super-Twisting滑模控制研究

为了对基于U模型的非线性控制系统进行研究,利用Super-Twisting控制算法,解决非仿射非线性系统的控制问题,对非线性函数进行神经网络逼近,运用Super-Twisting控制算法进行控制。选取恰当的Lyapunov函数,对Super-Twisting算法的收敛性进行了证明。为了验证该方法的可行性和有效性,利用Matlab软件进行仿真,结果表明在神经网络自适应Super-Twisting控制器的作用下,被控系统具有快速的跟踪性能和输出的有界性。