An Improved Robust Model Predictive Control Approach to Systems with Linear Fractional Transformation Perturbations

In this paper, a robust model predictive control approach is proposed for a class of uncertain systems with time-varying, linear fractional transformation perturbations. By adopting a sequence of feedback control laws instead of a single one, the control performance can be improved and the region of attraction can be enlarged compared with the existing model predictive control （MPC） approaches. Moreover, a synthesis approach of MPC is developed to achieve high performance with lower on-line computational burden. The effectiveness of the proposed approach is verified by simulation examples.

Robust control for a class of uncertain switched fuzzy systems

A model of uncertain switched fuzzy systems whose subsystems are uncertain fuzzy systems is presented. Robust controllers for a class of switched fuzzy systems are designed by using the Lyapunov function method. Stability conditions for global asymptotic stability are developed and a switching strategy is proposed. An example shows the effectiveness of the method.

Robust sliding mode control for uncertain discrete time systems

A novel variable structure control (VSC) strategy with a dynamic disturbance compensator based on the reaching law for a class of uncertain discrete systems is presented. The robust stability to disturbance and the system dynamics in the vicinity of the switching plane are studied. A measure of the uncertain parameters and external disturbance is obtained through delaying every sampling time. Theoretical analysis and experimental simulation results demonstrate that the dynamic performance and robustness of the closed-loop system are improved effectively.

Novel ARC-Fuzzy Coordinated Automatic Tracking Control of Four-Wheeled Mobile Robot

Four-wheeled,individual-driven,nonholonomic structured mobile robots are widely used in industries for automated work,inspection and explora-tion purposes.The trajectory tracking control of the four-wheel individual-driven mobile robot is one of the most blooming research topics due to its nonholonomic structure.The wheel velocities are separately adjusted to follow the trajectory in the old-fashioned kinematic control of skid-steered mobile robots.However,there is no consideration for robot dynamics when using a kinematic controller that solely addresses the robot chassis’s motion.As a result,the mobile robot has lim-ited performance,such as chattering during curved movement.In this research work,a three-tiered adaptive robust control with fuzzy parameter estimation,including dynamic modeling,direct torque control and wheel slip control is pro-posed.Fuzzy logic-based parameter estimation is a valuable tool for adjusting adaptive robust controller(ARC)parameters and tracking the trajectories with less tracking error as well as high tracking accuracy.This research considers the O type and 8 type trajectories for performance analysis of the proposed novel control technique.Our suggested approach outperforms the existing control methods such as Fuzzy,proportional–integral–derivative(PID)and adaptive robust controller with discrete projection(ARC–DP).The experimental results show that the scheduled performance index decreases by 2.77%and 4.76%.All the experimen-tal simulations obviously proved that the proposed ARC-Fuzzy performed well in smooth groud surfaces compared to other approaches.

码垛机器人的幂次指数趋近律变结构控制

为提高码垛机器人的控制精度,并保证系统在存在建模误差及扰动时的鲁棒性,设计了一种基于幂次指数趋近律的变结构控制算法。建立了二连杆机械臂数学模型,分析了三种趋近律的缺点,比较并提出了幂次指数趋近律。提出了使用求解微分方程的办法分三个阶段来研究算法的鲁棒性。分析了有界综合扰动极限值与控制器参数之间的关系。使用新算法得出了机器人在不含扰动时的仿真结果,解出了变结构控制三个阶段的微分方程,得出了机械臂在存有建模误差及扰动时的仿真结果。幂次指数趋近律变结构控制算法提高了码垛机器人的控制精度,在系统存在各种误差及扰动条件下具有极强鲁棒性并依然可以保证很高的控制精度。

一种新型永磁同步电机高阶滑模控制算法

针对永磁同步电机控制系统易因外部扰动等不确定性影响而导致控制性能下降的问题,提出了一种基于改进自适应非奇异终端滑模控制器和滑模扰动观测器补偿技术的复合控制算法。选择新型自适应指数趋近律设计非奇异终端滑模转速环控制器,新型趋近律可以在保证减少抖振的同时保证控制系统能够快速收敛,可动态适应被控系统的变化;利用扩展滑模扰动观测器实时估计系统中不确定性参数,并对控制器进行前馈补偿,且通过Lyapunov函数证明了其稳定性。仿真和试验结果表明,与PI控制、传统滑模控制方法相比,所提方法有效改善了抖振问题,提高了控制系统对电机的控制精度,提升了系统的鲁棒性和抗干扰性能。

基于非奇异快速积分终端滑模的机械臂鲁棒控制

为了克服机械摩擦、未知负载和模型误差等不确定性因素对机械臂控制精度的影响,采用指数障碍李雅普诺夫函数设计了非奇异快速积分终端滑模有限时间鲁棒控制律。首先,建立了带有各类不确定性因素的机械臂数学模型,并通过设计的观测器准确地估计出干扰值;然后,利用机械臂转角误差设计了非奇异快速积分终端滑模面,在指数障碍李雅普诺夫函数的基础上,设计出了有限时间鲁棒控制律;最后,通过稳定性分析验证了设计的有限时间鲁棒控制律能够在有效时间内收敛。三自由度机械臂的仿真结果表明:提出的有限时间鲁棒控制律能够有效克服不确定性因素对机械臂控制精度的影响,观测器的最大估计误差为0.1(°)/s 2,机械臂各关节转角的最大跟踪误差为0.1°,验证了设计方法的有效性。在三维空间固定坐标定位实验中,机械臂在提出的有限时间鲁棒控制律作用下的最大定位误差为0.22 cm,最长运行时间为2.2 s,验证了在实际工程应用中能够实现更高的控制精度和运行效率。

An Adaptive Fuzzy Control Model for Multi-Joint Manipulators

Multi-joint manipulator systems are subject to nonlinear influences such as frictional characteristics,random disturbances and load variations.To account for uncertain disturbances in the operation of manipulators,we propose an adaptive manipulator control method based on a multi-joint fuzzy system,in which the upper bound information of the fuzzy system is constant and the state variables of the manipulator control system are measurable.The control algorithm of the system is a MIMO(multi-input-multi-output)fuzzy system that can approximate system error by using a robust adaptive control law to eliminate the shadow caused by approximation error.It can ensure the stability of complex manipulator control systems and reduce the number of fuzzy rules required.Comparison of experimental and simulation data shows that the controller designed using this algorithm has highly-precise trajectory-tracking control and can control robotic systems with complex characteristics of non-linearity,coupling and uncertainty.Therefore,the proposed algorithm has good practical application prospects and promotes the development of complex control systems.

Robust output-feedback stabilization of a class of nonlinear systems with the nonlinearities of varied form

The back-stepping designs based on confine functions are suggested for the robust output-feedback global stabilization of a class of nonlinear continuous systems; the proposed stabilizer is efficient for the nonlinear continuous systems confined by a bound function, the nonlinearities of the systems may be of varied forms or uncertain; the designed stabilizer is robust means that a class of nonlinear continuous systems can be stabilized by the same output feedback stabilization schemes; numerical simulation examples are given.

Sliding mode control of engine-variable pump-variable motor drive system

Engine-variable pump-variable motor drive system is a complex nonlinear system. In order to improve system response speed and stability,a sliding-mode variable-structure control based on a feedback linearization theory is analyzed in this research. A standardized system model is established and linearized by the feedback linearization theory,and the input dimension is reduced through the relationship between variables which has simplified the linearization process. Then the sliding-mode controller using an exponential reaching law is designed and the Lyapunov stability of this algorithm is verified. The simulation results show that the sliding-mode variable-structure controller based on the feedback linearization theory can improve system response speed,reduce overshoot and achieve stronger robustness,so the vehicle speed control requirements can be satisfied well.

基于终端滑模的六旋翼无人机有限时间鲁棒控制

为了提高六旋翼无人机在复合扰动下的控制效果,设计一种终端滑模鲁棒控制方法,能够在有限时间内实现稳定控制。建立六旋翼无人机的运动与姿态模型,在运动模型鲁棒控制律设计过程中,引入终端滑模来改善控制效果,并设计自适应律来补偿复合干扰;在姿态模型鲁棒控制律的设计过程中,提出终端滑模模糊系统来补偿复合干扰;在有限时间内实现了六旋翼无人机的全局渐进稳定。实验结果表明,提出的终端滑模有限时间鲁棒控制律与一般滑模控制方法相比,具有更优的稳定性、准确性和快速性,能够在0.1 s内实现全局鲁棒控制,位置和姿态的最大跟踪误差分别仅为0.1 m和0.3°,有效提升了六旋翼无人机的鲁棒性。

基于滑模自抗扰控制的变绳长塔机防摆控制

塔式起重机在实际应用中,由于绳长的变化会加剧负载(货物)的摆动,使得货物很难被快速、准确地运输到指定的位置。因此,为了对塔式起重机负载进行精确定位及防摆控制,提出了一种基于滑模自抗扰控制(SM-ADRC)的变绳长塔机防摆控制方法。首先,根据拉格朗日方程得出了系统的动力学方程,并依据动力学方程将系统分为了变幅、回转、提升3个子系统,并对每个子系统分别设计了线性扩张状态观测器(LESO),观测和补偿了对应回路中因参数变化、系统耦合及外界因素引起的未知总干扰;然后,结合滑模控制(SMC),设计了带有干扰补偿的非线性误差反馈控制律;最后,在MATLAB/Simulink中,在快速性、鲁棒性方面,对比分析了滑模控制方法与滑模自抗扰控制方法的控制性能。研究结果表明:相比于滑模控制方法,滑模自抗扰控制方法对塔机防摆控制时间缩短了25.5%,并且该方法不仅可以提高塔机的快速响应性能,而且具有较强的鲁棒性和自适应性,可以对塔式起重机负载进行精确定位及有效的防摆控制。

基于自适应改进终端滑模的船舶航向控制

针对船舶在航行过程中受到风、浪、流等外部环境和本身参数不确定性的影响,难以准确地跟踪期望航向的问题,设计了一种自适应改进非奇异终端滑模控制器(AINTMSC),该控制器引入自适应控制理论,对滑模控制中的趋近律增益进行自适应校正,同时对非奇异终端滑模面进行改进,提高系统收敛速度,最后利用Lyapunov稳定性理论证明了该控制算法的稳定性。以大连海事培训船“育龙”号为研究对象并利用Simulink进行仿真实验验证。实验结果表明,与常规的非奇异终端滑模控制器(NTMSC)相比,AINTMSC航向控制器具有响应速度快、控制精度高、能耗低等优势,其对风浪干扰和参数摄动都有较强的鲁棒性,控制效果良好。

基于新型指数趋近律的直流充电桩整流器改进滑模控制

针对电动汽车直流充电桩AC/DC整流器运行条件复杂,工况频繁切换,其直流侧输出电压存在较大波动和超调的问题,提出了一种基于新型指数趋近律的滑模控制方法,以提高直流电压控制单元对扰动的快速响应与跟踪。首先,从机理上对目前充电桩三相AC/DC整流器控制方法的不足之处进行分析。其次,针对传统滑模控制中存在收敛速度缓慢和抖振的现象,在滑模面趋近律函数的构建中,提出新型指数趋近律,并以饱和函数替代符号函数,有效提高充电桩整流器控制系统的收敛速度,减小抖振。最后,在理论和仿真分析的基础上,进行负荷大扰动实验分析。结果表明,所提出的控制方法比传统PI和滑模控制具有更快的动态响应速度、更好的鲁棒性和稳定性,能够更好地适应负载的变换。

移动装配机器人手臂的滑模鲁棒控制方法

为了克服外界干扰、未知负载等不确定性和电机动态特性对移动装配机器人手臂末端空间轨迹跟踪的影响,提出了一种基于扩张状态观测器的滑模鲁棒控制律。首先建立了包含不确定性和电机动态特性的数学模型,然后设计了扩张状态观测器来准确估计不确定性,在此基础上提出了滑模鲁棒控制律,最终实现了对移动装配机器人手臂末端空间轨迹跟踪的高精度控制。仿真结果表明,所设计的滑模鲁棒控制律具有更优的控制效果,移动装配机器人手臂末端空间轨迹的最大跟踪误差仅为0.5 cm,所设计的扩张状态观测器能够准确估计不确定性,最大估计误差仅为0.2 N·m,估计精度较高。移动装配机器人手臂空间固定坐标定位实验结果表明,在基于扩张状态观测器的滑模鲁棒控制律的作用下,移动装配机器人手臂末端空间轨迹的最大跟踪误差仅为0.24 cm,平均每次定位的运行时间仅为1.55 s,表现出了更优的快速性、准确性和工程实用性。

改进趋近律的板球系统鲁棒滑模控制

板球系统作为一种非线性的不稳定系统,影响系统的不确定因素较多。针对系统中的扰动问题,提出了一种基于趋近律的滑模控制方案。首先,系统建模时将非线性系统进行解耦,实现线性化处理,假设系统在不良环境下受到多种干扰,故在系统建模时对平板与小球同时引入不确定扰动;其次,依据Hurwitz条件设计滑模函数,在控制器的设计中对指数趋近律进行改进;定义Lyapunov函数,根据LaSalle不变性原理证明闭环系统渐进稳定;最后,利用Simulink进行仿真实验,结果表明所设计的控制方案在不同的干扰下,轨迹跟踪误差较小,系统响应速度较快,具有良好轨迹跟踪和抗干扰性能。

非线性变结构制导律

为使导弹制导系统具有良好的鲁棒性能和适应性能,本文基于Lyapunov稳定性理论,利用滑模控制来设计导弹的末端导引规律。考虑结构摄动和目标机动加速度的界未知情况下,提出了一种基于零化视线法向速度的具有强鲁棒性的末端导引规律,这种制导律在保证系统闭环稳定的前提下能够在线对结构摄动和目标机动加速度的界进行估计。仿真验证说明所提出的方法是有效的。

基于趋近律方法的离散时间系统变结构控制

对变结构控制设计中的离散趋近律方法进行深入研究,提出了"理想趋近律"与"鲁棒趋近律"的概念.基于这些概念可以将离散趋近律区分为两类.研究了采用不同类型趋近律求取变结构控制时的异同及鲁棒性保证机理.澄清了使用趋近律方法设计变结构控制时存在的混乱和误解.

时变通信延迟下的无人机编队鲁棒自适应控制

在时变通信延迟下研究了无人机群编队的鲁棒自适应控制问题。对于无人机编队系统中存在外部扰动和模型不确定性的情况,通过选取包含位置跟踪误差和速度跟踪误差的辅助变量,提出了一种适用于时变通信延迟的鲁棒自适应编队控制策略。提出了自适应律对无人机质量、外界扰动的上界等未知参数进行估计,并且利用Lyapunov稳定性理论分析了闭环系统的渐近稳定性,给出了系统渐近稳定所需要满足的条件。数值仿真结果表明,所提出的控制方法既能抑制外界扰动和模型不确定性对控制器的影响,同时队形跟踪和队形保持的稳态误差分别小于0.1 m和0.05 m。