Fuzzy variable structure delay control algorithms and their applications to AQM

This paper analyzes the fuzzy variable structure control algorithms for delay systems and describes the compensation mechanism of the integral factor to the effect of the delay. Based on the linearized model of the congestion-avoidance flow-control mode of transmission control protocol (TCP), we present delay control algorithms for active queue management (AQM) and discuss the parameter tuning of the algorithms. The NS (network simulator) simulation results show that the proposed control scheme for the nonlinear TCP/AQM model has good performance and robustness with respect to the uncertainties of the round-trip time (RTT) and the number of active TCP sessions. Compared to other similar schemes, our algorithms perform better in terms of packet loss ratio, throughput and butter fluctuation.

Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system,adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty.At the same time,gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort.The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome.On the other hand,the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy,and the chattering phenomenon of the control effort is also suppressed effectively.

Fuzzy variable structure algorithms for active queue management with delay compensation

Based on the linearized model of the TCP connections through the congested routers, this paper puts forward an active queue management algorithm (FVS-T). The algorithm utilizes the fuzzy variable structure control algorithm with delay factor to compensate time varying round-trip times (RTT) and uncertainties with respect to the number of active TCP sessions. By analyzing the robustness and performance of the control scheme for the nonlinear TCP/AQM model, we show that the proposed design has good performance and robustness, which are central to the notion of AQM. Implementation issues were discussed and ns simulations were provided to validate the design and compare its performance to other peer schemes in different scenarios. The results show that the proposed design significantly outperforms the other congestion schemes in terms of packet loss ratio, throughput and buffer fluctuation.

Independent modal variable structure fuzzy active vibration control of thin plates laminated with photostrictive actuators

Photostrictive actuators can produce photodeformation strains under illumination of ultraviolet lights. They can realize non-contact micro-actuation and vibration control for elastic plate structures. Considering the switching actuation and nonlinear dynamic characteristics of photostrictive actuators, a variable structure fuzzy active control scheme is presented to control the light intensity applied to the actuators. Firstly, independent modal vibration control equations of photoelectric laminated plates are established based on modal analysis techniques. Then, the optimal light switching function is derived to increase the range of sliding modal area, and the light intensity self-adjusting fuzzy active controller is designed. Meanwhile, a continuous function is applied to replace a sign function to reduce the variable structure control （VSC） chattering. Finally, numerical simulation is carried out, and simulation results indicate that the proposed control strategy provides better performance and control effect to plate actuation and control than velocity feedback control, and suppresses vibration effectively.

Adaptive Sliding Mode Control for MIMO Nonlinear Systems Based on Fuzzy Logic Scheme

In this study an indirect adaptive sliding mode control (SMC) based on a fuzzy logic scheme is proposed to strengthen the tracking control performance of a general class of multi-input multi-output (MIMO) nonlinear uncertain systems. Combining reaching law approach and fuzzy universal approximation theorem, the proposed design procedure combines the advantages of fuzzy logic control, adaptive control and sliding mode control. The stability of the control systems is proved in the sense of the Lyapunov second stability theorem. Two simulation studies are presented to demonstrate the effectiveness of our new hybrid control algorithm.

A kind of fuzzy control for chaotic systems

With a T-S fuzzy dynamic model approximating to a non-linear system,the nonlinear system can be decomposed into some local linear models.A variable structure controller based on Lyapunov theories is designed to guarantee the global stability of the T-S fuzzy model.The controlling problems of a nonlinear system can be solved by means of consisting of linear system variable structure control and fuzzy control.The validity of the control method based on the simulating result of two kinds of chaotic systems is shown here.

Research on Robust Control of Nonlinear Fuzzy VSS for Spacecraft

The nonlinear dynamic system of spacecraft with uncertainty and coupling is analyzed and its general dynamical equation is given.The decoupling-ability and controllability are proved.Aiming at this system,a new nonlinear decoupling controlling method is put forward by synthetically using the variable structure and fuzzy theory.The simulation results show that this method is effective in tracking performances under the existence of uncertainty and outer disturbance.

基于混沌控制的采摘机器人防碰撞系统设计

针对采摘机器人在作业过程中遇到障碍物导致路径规划出现混沌现象的问题,基于混沌控制对采摘机器人防碰撞系统进行设计,并采用模糊自适应控制算法和滑模变结构控制算法结构的方式对系统进行控制。为了验证防碰撞系统的有效性,对采摘机器人进行了防碰撞和采摘仿真试验,结果表明:采摘机器人在作业过程中可以避开障碍物,按照规划路线到达预设位置,完成果蔬的采摘。

融合反步法的无人驾驶汽车轨迹跟踪控制方法

为了解决无人驾驶汽车轨迹跟踪控制的准确性、稳定性和快速性问题,将反步法分别融合滑模变结构控制和模糊自适应控制.建立车辆三自由度运动学位姿误差微分方程,推导了基于反步法的车速和横摆角速度控制律,结合Lyapunov稳定性判据验证了系统稳定性.分别建立融合反步法的滑模变结构和模糊自适应轨迹跟踪控制方法,结合轨迹跟踪稳态误差、超调量和调整时间,验证、比较了控制方法准确性、稳定性和快速性3种性能的优劣.结果表明:融合反步法的滑模变结构轨迹跟踪控制的稳定性最好,轨迹跟踪超调量接近于0;融合反步法的模糊自适应轨迹跟踪控制快速性最好,轨迹跟踪调整时间相对于反步法缩短了18.2%.

Attitude tracking control for variable structure near space vehicles based on switched nonlinear systems

An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle （VSNSV） in the presence of uncertainties and disturbances. The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online. To improve the flight robust performance, robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation. Moreover, a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control （DSC） approach. According to the common Lyapunov function theory, it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller. The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.

基于神经网络优化直/气复合控制导弹迅捷转弯

空空导弹迅捷转弯控制是在保证导弹稳定飞行的前提下,在尽可能短的时间内完成整个机动过程。为实现上述战术指标,考虑到导弹迅捷转弯的快时变性、强非线性和大干扰性,设计基于滑模变结构控制和模糊逻辑的直/气复合控制器。针对实际飞行中可能出现的初值不确定和外界干扰过大等现象,引入固定时间收敛理论和扩张状态观测器,有效避免干扰带来的控制输入抖振并保证导弹姿态角能在固定时间内快速稳定收敛。利用神经网络对滑模变结构控制的设计参数进行优化,在保证导弹迅捷转弯的同时减轻导弹侧向发动机的质量。通过仿真验证新提出的控制和分配方案的有效性。研究结果表明,所设计的控制器在存在模型不确定性和外部干扰等复杂情况下具一定的鲁棒性、稳定平滑的控制效果、较强的抗干扰能力以及优异的姿态跟踪性能,同时参数优化后的控制算法跟踪效果更优,在降低了原收敛时间的12.6%的同时,降低了原最大控制力的9.6%。

基于模糊控制的永磁同步电机协同控制

多电机协同控制系统中存在变量多、耦合程度高等问题,使得系统的同步误差较大、启动时间久。基于传统自抗扰控制方案,提出用滑模变结构控制策略优化自抗扰控制,提高了单电机的跟踪精度;设计模糊自调整控制方案优化同步误差。在MATLAB/SIMULINK下搭建两台电机交叉耦合控制模型,并与传统固定增益的相邻交叉耦合方案进行对比,结果显示:该方案可以有效提高控制精度,在面对扰动影响时能够快速恢复稳定,且恢复稳定所用时间显著缩短。

汽车ABS模糊变结构控制设计

针对汽车制动过程中防抱死制动系统(ABS)存在的难以充分利用地面附着系数和高度非线性的问题,提出了一种基于路面识别的ABS模糊变结构控制策略。利用Burckhardt轮胎模型设计路面识别算法,并通过模糊变结构控制调节路面识别算法识别出的最优滑移率。仿真实验结果表明,路面识别算法响应速度快、准确率高;在跃变路面条件下,模糊变结构控制比变结构控制的制动时间减少7%,制动距离缩短6%,控制器输出的抖振幅度得到有效削弱.

模糊神经网络滑模控制在高压电极热水锅炉液位控制系统中的应用

针对某公司生产的高压电极热水锅炉在工作过程中的高阶性、非线性及强耦合等特性以及用户对高压电极热水锅炉在电网侧调频调峰应用中的功率稳定性、响应快速性的严苛要求,而现有的控制策略难以满足精确控制(主要指功率)要求的实际情况,提出了一种将模糊神经网络控制与滑模变结构控制相结合的先进PID控制器,使其应用在高压电极热水锅炉的液位控制系统中。实验结果显示,将该控制器应用到高压电极热水锅炉的液位控制系统中,可有效克服上述系统的不良特性且有较好的稳定性和响应快速性,能够满足电网侧对电极锅炉在调频调峰中功率稳定性、响应快速性的要求。

基于模糊变结构补偿的机械臂运动路径避障规划算法

机械臂的活动范围可以自由调整,其准确的运动规律较难获取,导致机械臂运动路径避障规划存在规划效果差、规划路径长以及规划耗时长的问题,为此提出基于模糊变结构补偿的机械臂运动路径避障规划算法。该算法首先对机械臂进行相关动力学分析,将分析结果与模糊变结构相结合对机械臂力矩进行补偿控制;然后使用Q-learning算法计算补偿控制结果,获取路径最佳规划策略;最后通过该策略完成机械臂避障路径的规划。实验结果表明,使用该算法进行路径规划时的规划结果较为准确,规划路径短且规划耗时短。

模糊变结构控制策略在UUV航向运动中的应用与分析

无人水下航行器(UUV)在实现预期运动时,被控对象会受到不同性质的扰动,为满足当前UUV水下空间运动的精准控制,要求航行控制系统在完成航向跟踪基本性能的前提下兼备一定的抗扰性能。以变结构控制策略设计为基础,针对非线性控制中的抖振现象,提出一种模糊化控制策略的设计以提高跟踪效果,通过Lyapunov函数设计UUV侧向运动变结构控制器及其模糊化控制器来实现UUV快速精准的航向控制,利用Simulink仿真验证航向跟踪控制性能,并计算分析对比变结构控制策略和其模糊化控制策略下UUV在航向运动中的抗扰性,仿真结果表明了模糊化变结构控制策略在UUV航向控制中具备良好的稳定性与抗扰性等特点,同时能很好地抑制抖振。

RLPG电液定量伺服加注系统设计与仿真研究

为了实现RLPG的液体发射药自动加注,设计了其电液定量伺服加注系统。通过控制阀控定量缸中活塞位移实时调整无杆腔中发射药量,实际应用过程中,定量过程与复位过程、火炮发射过程无冲,可并行工作。针对电液伺服系统模型不确定性、非线性的特点,建立了其状态空间模型。为了改善滑模变结构控制的抖振现象,设计了该系统的模糊滑模变结构控制器。搭建了AMESim/Simulink联合仿真平台,在不同装药量下对系统进行仿真分析,结果表明,定量过程所需时间比RLPG发射时间与变装药活塞复位时间之和小得多,加注0.6283 L液体发射药共需0.95 s;随着装药量增加,系统定量精度有所下降,但均保持在99.85%以上。

永磁同步电机滑模变结构与模糊PID复合控制研究

该文针对永磁同步电机矢量控制系统的速度环,引入了滑模变结构与模糊PID控制理论,设计了一种滑模变结构与模糊PID复合控制器。该复合控制器通过一个可变加权因子α将滑模变结构控制与模糊PID控制有效地组合起来实现对速度的调节。此种控制方法克服了对永磁同步电机精准数学模型的依赖,使得系统响应的快速性更好,稳定性、鲁棒性和抗干扰能力更强,静态和动态特性更优,对多种智能复合控制方法综合研究有一定的参考意义。

基于变论域模糊控制的时变结构震动控制方法研究

针对传统工程震动控制领域控制对象均为确定结构,未考虑实际结构在地震的过程中及地震前可能会发生的刚度退化、质量降低问题,该文章以时变三层框架结构作为被控对象,在传统模糊控制算法的基础上引入变论域法,建立了基于变论域模糊控制的时变结构震动控制方法。通过在传统主模糊控制器增设伸缩因子模糊控制器,将被控对象的误差及误差变化率作为输入,伸缩因子作为输出,根据被控对象的误差及误差变化率自适应调整主模糊控制器的模糊论域。SIMULINK软件仿真结果表明,所提出的控制方法能实现模糊控制论域自适应调整,针对时变结构位移、速度、加速度的控制效果均优于传统模糊控制和ON-OFF控制算法,具有一定工程应用前景。

一种有视线角约束的模糊变系数变结构制导律

针对有末端视线角约束下拦截高速机动目标的场景,设计了一种模糊变系数变结构制导律。提出了一种自适应变结构制导律,制导律可以根据弹目距离自适应调整趋近滑模面的速度;用饱和函数代替制导律中的开关项,有效消除了系统抖振。仿真表明,拦截高速非机动和高速机动目标,提出的变结构制导律均可以满足视线角约束和脱靶量要求,但需用过载较大。为解决需用过载较大的问题,引入模糊控制方法,设计模糊控制器对变结构制导律中的导引系数进行优化,得到了一种模糊变系数变结构制导律,可以满足视线角约束且有效抑制了系统的需用过载。