The Non-Singular Fast Terminal Sliding Mode Control of Interior Permanent Magnet Synchronous Motor Based on Deep Flux Weakening Switching Point Tracking

This paper presents a novel non-singular fast terminal sliding mode control(NFTSMC)based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior magnet synchronous motor(IPMSM)drive systems.The mathematical model of flux weakening(FW)control is established,and the deep flux weakening switching point is calculated accurately by analyzing the relationship between the torque curve and voltage decline curve.Next,a second-order NFTSMC is designed for the speed loop controller to ensure that the system converges to the equilibrium state in finite time.Then,an extended sliding mode disturbance observer(ESMDO)is designed to estimate the uncertainty of the system.Finally,compared with both the PI control and sliding mode control(SMC)by simulations and experiments with different working conditions,the method proposed has the merits of accelerating convergence,improving steady-state accuracy,and minimizing the current and torque pulsation.

Nonsingular Fast Terminal Sliding Mode Control Based on Nonlinear Disturbance Observer for a Quadrotor

Given external disturbances and system uncertainties,a nonsingular fast terminal sliding mode control(NFTSMC)method integrated a nonlinear disturbance observer(NDO)is put forward for quadrotor aircraft.First,a NDO is proposed to estimate the actual values of uncertainties and disturbances.Second,the NFTSM controller based on the reaching law is designed for the attitude subsystem(inner loop),and the control strategy can ensure Euler angles’fast convergence and stability of the attitude subsystem.Moreover,the NFTSMC strategy combined with backstepping is proposed for the position subsystem(outer loop),which can ensure subsystem tracking performance.Finally,comparative simulations show the trajectory tracking performance of the proposed method is superior to that of the traditional sliding mode control(SMC)and the SM integral backstepping control under uncertainties and disturbances.

Grey Wolf Optimization Based Tuning of Terminal Sliding Mode Controllers for a Quadrotor

The research on Unmanned Aerial Vehicles(UAV)has intensified considerably thanks to the recent growth in the fields of advanced automatic control,artificial intelligence,and miniaturization.In this paper,a Grey Wolf Optimization(GWO)algorithm is proposed and successfully applied to tune all effective parameters of Fast Terminal Sliding Mode(FTSM)controllers for a quadrotor UAV.A full control scheme is first established to deal with the coupled and underactuated dynamics of the drone.Controllers for altitude,attitude,and position dynamics become separately designed and tuned.To work around the repetitive and time-consuming trial-error-based procedures,all FTSM controllers’parameters for only altitude and attitude dynamics are systematically tuned thanks to the proposed GWO metaheuristic.Such a hard and complex tuning task is formulated as a nonlinear optimization problem under operational constraints.The performance and robustness of the GWO-based control strategy are compared to those based on homologous metaheuristics and standard terminal sliding mode approaches.Numerical simulations are carried out to show the effectiveness and superiority of the proposed GWO-tuned FTSM controllers for the altitude and attitude dynamics’stabilization and tracking.Nonparametric statistical analyses revealed that the GWO algorithm is more competitive with high performance in terms of fastness,non-premature convergence,and research exploration/exploitation capabilities.

Precise robust motion control of cell puncture mechanism driven by piezoelectric actuators with fractional-order nonsingular terminal slidingmode control

A novel robust controller is proposed in this study to realize the precise motion control of a cell puncture mechanism(CPM)driven by piezoelectric ceramics(PEAs).The entire dynamic model of CPM is constructed based on the Bouc–Wen model,and the nonlinear part of the dynamic model is optimized locally to facilitate the construction of a robust controller.A model-based,nonlinear robust controller is constructed using time-delay estimation(TDE)and fractional-order nonsingular terminal sliding mode(FONTSM).The proposed controller does not require prior knowledge of unknown disturbances due to its real-time online estimation and compensation of unknown terms by using the TDE technology.The controller also has finite-time convergence and high-precision trajectory tracking capabilities due to FONTSM manifold and fast terminal sliding mode-type reaching law.The stability of the closed-loop system is proved by Lyapunov stability theory.Computer simulation and hardware-in-loop simulation experiments of CPM verify that the proposed controller outperforms traditional terminal sliding mode controllers,such as the integer-order or model-free controller.The proposed controller can also continuously output without chattering and has high control accuracy.Zebrafish embryo is used as a verification target to complete the cell puncture experiment.From the engineering application perspective,the proposed control strategy can be effectively applied in a PEA-driven CPM.

Fuzzy Fractional-Order Fast Terminal Sliding Mode Control for Some Chaotic Microcomponents

In this paper, we propose a novel fractional-order fast terminal sliding mode control method, based on an integer-order scheme, to stabilize the chaotic motion of two typical microcomponents. We apply the fractional Lyapunov stability theorem to analytically guarantee the asymptotic stability of a system characterized by uncertainties and external disturbances. To reduce chattering, we design a fuzzy logic algorithm to replace the traditional signum function in the switching law. Lastly, we perform numerical simulations with both the fractional-order and integer-order control laws. Results show that the proposed control law is effective in suppressing chaos. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

Decoupled nonsingular terminal sliding mode control for affine nonlinear systems

A decoupled nonsingular terminal sliding mode control（DNTSMC） approach is proposed to address the tracking control problem of affine nonlinear systems.A nonsingular terminal sliding mode control（NTSMC） method is presented,in which the nonsingular terminal sliding surface is defined as a special nonsingular terminal function and the convergence time of the system states can be specified.The affine nonlinear system is firstly decoupled into linear subsystems via feedback linearization.Then,a nonsingular terminal sliding surface is defined and the NTSMC method is applied to each subsystem separately to ensure the finite time convergence of the closed-loop system.The verification example is given to demonstrate the effectiveness and robustness of the proposed approach.The proposed approach exhibits a considerable advantage in terms of faster tracking error convergence and less chattering compared with the conventional sliding mode control（CSMC）.

Non-Negative Adaptive Mechanism-Based Sliding Mode Control for Parallel Manipulators with Uncertainties

In this paper,a non-negative adaptive mechanism based on an adaptive nonsingular fast terminal sliding mode control strategy is proposed to have finite time and high-speed trajectory tracking for parallel manipulators with the existence of unknown bounded complex uncertainties and external disturbances.The proposed approach is a hybrid scheme of the online non-negative adaptive mechanism,tracking differentiator,and nonsingular fast terminal sliding mode control(NFTSMC).Based on the online non-negative adaptive mechanism,the proposed control can remove the assumption that the uncertainties and disturbances must be bounded for the NFTSMC controllers.The proposed controller has several advantages such as simple structure,easy implementation,rapid response,chattering-free,high precision,robustness,singularity avoidance,and finite-time convergence.Since all control parameters are online updated via tracking differentiator and non-negative adaptive law,the tracking control performance at high-speed motions can be better in real-time requirement and disturbance rejection ability.Finally,simulation results validate the effectiveness of the proposed method.

Terminal Sliding Mode Fuzzy Control Based on Multiple Sliding Surfaces for Nonlinear Ship Autopilot Systems

A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which takes account of rudder characteristics and parameter uncertainty. In order to solve the problem, the controller was designed by employing the universal approximation property of fuzzy logic system, the advantage of Nussbaum function, and using multiple sliding mode control algorithm based on the recursive technique. In the last step of designing, a nonsingular terminal sliding mode was utilized to drive the last state of the system to converge in a finite period of time, and high-order sliding mode control law was designed to eliminate the chattering and make the system robust. The simulation results showed that the controller designed here could track a desired course fast and accurately. It also exhibited strong robustness peculiarly to system, and had better adaptive ability than traditional PID control algorithms.

基于NFTSMC的分布式驱动电动汽车稳定性控制

为提高分布式驱动电动汽车在极限行驶工况下的稳定性,提出了一种具有三层结构的直接横摆力矩控制策略。顶层控制器解析驾驶人期望行驶状态值;上层控制器采用非奇异快速终端滑模控制(NFTSMC),决策维持车辆稳定行驶所需附加横摆力矩;下层控制器以车辆稳定裕度最大为目标,以电机输出极限、路面附着极限、轮胎纵/侧向力耦合关系为约束,基于加权最小二乘法实现4轮力矩动态优化分配。基于MATLAB/Simulink和Carsim仿真平台开展仿真试验。结果表明:相比滑模控制,车速为70 km/h时,双移线和正弦迟滞工况下,质心侧偏角最大跟踪误差分别减小66.7%、45.8%,均方根误差分别减小64.8%、56.4%,可见该策略能够提高期望状态跟踪精确性,改善车辆在极限行驶工况下的稳定性。

基于改进非线性滑模控制的轮式机器人轨迹跟踪

针对轮式机器人的轨迹跟踪控制存在的问题,设计了一种改进非线性快速终端滑模控制器(improved nonlinear fast terminal sliding mode controller,INFTSMC)的控制方案。首先,通过对轮式机器人运动学的分析建立了轨迹跟踪误差模型;其次,在设计滑模控制器阶段,针对非线性快速终端滑模控制器存在奇异点,采用一种新的滑模面幂指数时变策略来设计非奇异终端滑模控制器,解决了非线性快速终端滑模控制器奇异问题,通过构造Lyapunov函数进行稳定性分析证明了该策略的稳定性,并且进行收敛时间分析给出系统从任意初始状态收敛至平衡点所需要的时间;然后,在新的滑模面幂指数时变策略的基础上设计了轮式机器人线速度和角速度控制律,使得轮式机器人轨迹跟踪误差快速收敛至0,实现了移动机器人对期望轨迹的快速跟踪。通过仿真实验与非线性快速终端滑模控制器和传统滑模控制其进行对比,验证了改进非线性快速终端滑模控制器的优越性。

PMSM无模型超螺旋快速积分终端滑模控制

针对永磁同步电机运行过程中因模型不确定、参数摄动和外部扰动等因素的影响,从而导致驱动系统性能下降的问题,提出一种新型控制策略。首先,为减少对系统数学模型的依赖,构建了一个新的超局部模型,用于描述永磁同步电机的转速环。其次,基于转速环的新型超局部模型,结合一种新型积分终端滑模面和改进超螺旋控制律来设计新型无模型超螺旋快速积分终端滑模控制器,实现了对转速的精确控制。再次,采用非奇异快速终端滑模面和双幂次趋近律设计改进扩展非奇异终端滑模扰动观测器,通过精确观测和前馈补偿未知扰动,有效地抑制参数摄动和外部扰动,增强了系统鲁棒性,提高系统的动态性能和稳态性能。最后,通过与传统控制方法的仿真和实验对比,证实所提算法转速抗超调能力提升为0.412 5%,转矩快速响应能力提升0.013 s。结果表明当存在未知扰动时,所提方法具有较强的鲁棒性和良好的抗干扰性。

无人机舵面故障高阶滑模重构观测器设计及主动容错控制

针对无人机舵面损伤故障容错问题,提出了基于二阶非奇异终端滑模重构观测器及主动容错设计方法。在分析舵面正常偏转运动学和动力学特性基础上,构建了无人机典型舵面故障非线性特性模型。提出无人机舵面故障的高阶滑模重构滑模观测器设计方案;引入线性变换降维简化观测器设计程式;将终端滑模和非奇异终端滑模结合起来,实现滑模运动有限时间快速收敛;综合自适应律、线性矩阵不等式设计观测器系数矩阵,确保状态估计偏差有界稳定。提出集状态与故障重构于一体的主动容错控制方案,并通过仿真算例检验所提方案的有效性。

非最小相位的单电感双输出Buck-Boost变换器的复合控制方法

单电感双输出Buck-Boost (SIDO Buck-Boost)变换器在电感电流连续模式(CCM)下工作存在交叉影响以及非最小相位特性的问题.为了解决上述问题,提出基于储能函数的扩张状态观测器(ESO)的改进非奇异快速终端滑模(NFTSM)和自抗扰控制(ADRC)相结合的控制策略.设计主路控制器,对系统的传递函数进行拟合得到ADRC范式,利用该范式对主路进行解耦控制.设计支路控制器,采用改进型ESO对储能函数进行观测,并将观测值反馈补偿到非奇异快速终端滑模控制律中,达到支路解耦的效果.为了抑制滑模控制的抖振问题,对趋近律进行改进.利用Lyapunov理论证明系统稳定性.基于硬件在环(HIL)实验平台进行实验验证.结果表明,所提控制策略与PI控制策略以及基于ESO的滑模控制策略相比,在超调量和响应时间上具有较好的效果.

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.

永磁同步电机非线性增益非奇异快速终端滑模控制

为了研究传统滑模控制中系统误差在有限时间内无法收敛至0以及传统滑模控制中系统抖振与收敛速度互不兼容的问题,提出一种非奇异快速终端滑模控制与扰动观测器结合的速度控制器。通过将参数可变的非线性函数作为增益代替固定增益加入滑模控制策略中从而改善系统响应速度同时减小系统的抖振。针对转矩扰动对系统的影响,加入负载转矩扰动观测器并补偿到q轴电流中以进一步提高控制器抗负载扰动能力。根据李雅普诺夫稳定性理论对提出的新型滑模控制器进行稳定性证明,经过仿真和实验证明,电机在启动时响应快、无超调且抖振较小,在突加转矩时转速波动小且恢复时间迅速,证明了改进后的变增益非奇异终端滑模控制与传统非奇异快速终端滑模控制策略相比可以提高动态性能的同时抑制系统抖振、增强系统的鲁棒性。

故障检测与重构下基于AFTSMO的ROV三维航迹跟踪控制

针对传统的滑模观测器在缆控水下机器人(ROV)系统状态估计与故障重构过程中存在渐近收敛、无法及时准确重构故障信号的问题,提出一种基于自适应快速终端滑模观测器(adaptive fast terminal sliding mode observer)的故障检测和控制优化方法。建立带有推进器故障、未知外界干扰和模型参数不确定性等复合干扰的ROV系统故障模型;设计具有自适应特性的快速终端滑模控制器,保证所有的状态估计误差在有限时间内收敛;通过等效输出误差注入法对推进器引起的故障进行估计重构。采用Lyapunov稳定性理论验证控制系统的稳定性,仿真结果表明,所设计的故障检测方法能够快速检测和重构故障,保证ROV系统较高的跟踪精度,并通过实验验证了所提算法的有效性。

弱电网下基于超螺旋滑模的LCL并网逆变器控制研究

针对LCL型滤波器的固有谐振、滤波器参数及弱电网下电网阻抗的波动会严重破坏并网系统稳定性的问题,提出了弱电网下基于超螺旋滑模的LCL并网逆变器控制策略。根据并网系统模型构建超螺旋滑模观测器,对滤波电容电压及逆变器侧输出电流进行估计,消除额外传感器需要,降低成本。采用具有非奇异快速终端滑模面控制(NFTSMC)的超螺旋滑模控制器来快速地跟踪参考给定电流及降低并网系统动稳态误差,且提高并网系统对外界干扰和参数不确定性的全局鲁棒性。仿真结果表明,当滤波参数摄动和电网阻抗变化时,系统表现出较强的鲁棒性,且并网电流的THD值保持在0.5%左右。

不确定非线性系统快速终端滑模控制

针对界未知的非匹配不确定非线性系统轨迹快速跟踪控制,设计非线性干扰观测器(NDO)的反演自适应终端滑模控算法。首先设计子系统干扰观测器来确定界未知非匹配项补偿量,并结合子系统的Lyapunov函数求出反演控制中虚拟控制律,并运用指令滤波器解决虚拟项求导所带来的微分膨胀缺陷;再设计系统的非奇异快速终端滑模面并给出建模误差不确定性的自适应律,继而求出系统总控制律以确保总闭环系统有限时间全局渐近稳定;最后机器人动力学仿真案例表明,所设计的控制器能实现对指定轨迹的快速稳定跟踪,控制量光滑弱抖振,并对非匹配干扰具有较强的鲁棒性。

Improved Nonsingular Fast Terminal Sliding Mode Control of Unmanned Underwater Hovering Vehicle

An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper.It can significantly accelerate the convergence rate of the state error which is initially far from the origin and achieve the fixed-time convergence.In addition,conventional double power term based reaching law is improved to ensure the convergence of sliding state in the presence of disturbances.The proposed approach is applied to the hovering control of an unmanned underwater vehicle.The controller exhibits both fast convergence and strong robustness to model uncertainty and external disturbances.

直流伺服电机新型位置-速度控制策略

针对由直流电机位置伺服系统自身参数不确定以及外部扰动影响,导致系统响应速度、控制精度降低的问题,提出了一种新型位置-速度双环控制策略。速度控制器采用模糊内模PID(proportional-integral-differential)控制,利用模糊原理实现对内模PID控制器参数,即滤波时间常数λ的在线智能整定;位置控制器采用基于自抗扰的非奇异快速终端滑模控制(non-singular fast terminal sliding mode control,NFTSMC),利用线性扩张状态观测器对系统总体的内外干扰进行估计,并以反馈形式进行补偿,同时采用NFTSMC对系统的状态变量进行跟踪,以提高系统的跟踪性能和抗干扰性;最后使用仿真与实验方法验证了新型双闭环控制策略对直流电机位置伺服系统具有良好的控制性能。