非线性时滞系统自适应输出反馈跟踪控制

针对一类参数化非线性时滞输出反馈系统,提出了一种自适应输出跟踪控制器的设计方案。引入时滞滤波器估计未知系统状态,采用backstepping技术设计控制律和参数自适应律,运用占优方法处理非线性时滞项,从而放宽了对非线性时滞函数的要求,实现了对给定目标轨线的全局渐近跟踪,同时保证闭环系统所有信号一致有界。基于Lyapunov-Krasoviskii泛函方法证明了整个闭环系统的稳定性。实例仿真说明了该方案的可行性。     

Adaptive NN stabilization for stochastic systems with discrete and distributed time-varying delays

A new adaptive neural network(NN) output-feedback stabilization controller is investigated for a class of uncertain stochastic nonlinear strict-feedback systems with discrete and distributed time-varying delays and unknown nonlinear functions in both drift and diffusion terms.First,an extensional stability notion and the related criterion are introduced.Then,a nonlinear observer to estimate the unmeasurable states is designed,and a systematic backstepping procedure to design an adaptive NN output-feedback controller is proposed such that the closed-loop system is stable in probability.The effectiveness of the proposed control scheme is demonstrated via a numerical example.     

基于状态观测器的非线性系统神经网络自适应控制

结合高增益观测器,针对相对阶为n的非线性系统,设计了神经网络自适应控制器。利用Lyapnov定理获得了神经网络权值的更新律和控制器的控制律,从而确保了整个闭环系统的稳定性和有界性。由于神经网络不需任何的离线训练,因而该控制器能够广泛应用于一大类非线性性系统的控制中。仿真结果验证了控制方案的有效性。     

Adaptive control of system with hysteresis using neural networks

1.INTRODUCTIONThe piezoelectric actuators are well suited for micro-position devices in precision engineering because oftheir fast response,nanometer resolution and biggerdriving force[1].However,hysteresis inherent topiezoelectric actuator severely li mits system’s perfor-mance such as giving rise to undesirable accuracy oroscillations,even leading to instability.Hysteresischaracteristics are generally nondifferentiable andusually unknown.It is a difficult task to mitigate itsharmful ef…     

Backstepping tracking control for nonlinear time-delay systems

1. INTRODUCTION The presence of time delay has a significant effect on system performance and destroys the stability of closed-loop system[1]. Therefore, the study on time-delay systems has important practical significance. Recen- tly,considerable progress has been made in this field[1~10]. According to the dependency of the designed contr-oller depends on the time delay, the control approa-ches for time-delay systems can be classified into two categories: delay-dependent[2~3,10] and dela…     

一类时滞系统的模糊跟踪控制及其仿真

研究了一种基于模糊T-S模型的非线性时滞系统模糊跟踪控制问题。首先利用模糊T-S模型对不确定非线性系统进行模糊建模,然后在此基础上研究了模糊系统在状态可测与不可测的情况下的模糊跟踪问题。控制器的设计避开了复杂的精确反馈线性化与自适应方法。采用本方法,可将控制器的设计问题转化为求解线性矩阵不等式问题,再利用凸优化技术可将其有效地解决。因此该方法既简单又实用,并且通过仿真实例说明了它的有效性与正确性。     

Adaptive control method for nonlinear time-delay processes

Two complex properties,varying time-delay and block-oriented nonlinearity,are very common in chemical engineering processes and not easy to be controlled by routine control methods.Aimed at these two complex properties,a novel adaptive control algorithm the basis of nonlinear OFS(orthonormal functional series) model is proposed.First,the hybrid model which combines OFS and Volterra series is introduced.Then,a stable state feedback strategy is used to construct a nonlinear adaptive control algorithm that can guarantee the closed-loop stability and can track the set point curve without steady-state errors.Finally,control simulations and experiments on a nonlinear process with varying time-delay are presented.A number of experimental results validate the efficiency and superiority of this algorithm.     

一类非仿射受扰混沌系统的自适应模糊控制

针对一类带非仿射输入的不确定受扰混沌系统,提出了带监督控制项的自适应模糊控制。该方法采用模糊逻辑系统逼近虚拟控制中的未知函数,仅要求逼近误差范数有界。模糊参数采用σ自适应律,并给出参数的有界性证明。构造Lyapunov函数证明闭环系统所有信号一致有界,跟踪误差一致渐进稳定。将Duffing-Holmes系统、Genesio系统和Sprott电路混沌系统作为仿真对象,仿真结果验证了算法的有效性。     

Output feedback based adaptive robust fault-tolerant control for a class of uncertain nonlinear systems

An adaptive robust approach for actuator fault-tolerant control of a class of uncertain nonlinear systems is proposed. The two chief ways in which the system performance can degrade following an actuator-fault are undesirable transients and unacceptably large steady-state tracking errors. Adaptive control based schemes can achieve good final tracking accuracy in spite of change in system parameters following an actuator fault, and robust control based designs can achieve guaranteed transient response. However, neither adaptive control nor robust control based fault-tolerant designs can address both the issues associated with actuator faults. In the present work, an adaptive robust fault-tolerant control scheme is claimed to solve both the problems, as it seamlessly integrates adaptive and robust control design techniques. Comparative simulation studies are performed using a nonlinear hypersonic aircraft model to show the effectiveness of the proposed scheme over a robust adaptive control based faulttolerant scheme.     

不确定非线性系统的自适应输出机动控制

针对不可控不可稳定线性化的非线性系统,研究了鲁棒自适应输出机动控制问题。在未知时变参数的界未知的情况下,利用增加幂积分技术和鲁棒递推设计方法,构造了光滑自适应机动控制器。该控制器不仅能使闭环系统的输出以任意小的跟踪误差跟踪理想的参考路径,而且沿该路径还满足一定的动态任务,即可以使跟踪速度以任意小的误差跟踪预先给定的理想速度。仿真结果表明了该方法的有效性。     

基于神经网络的机械臂分散自适应跟踪控制

提出了一种适用于机械臂的基于神经网络的分散自适应轨迹跟踪控制方法。将机械臂的轨迹跟踪控制系统考虑为由多个非线性关联组成的不确定性复杂系统,采用分散控制方法进行控制器设计。在对每一子系统设计控制器时,采用直接反馈线性化,利用控制器构建伪线性系统,并引入神经网络自适应环节消除干扰、关联及逼近误差,从而使所提出的控制方法能够保证系统状态有较高的跟踪精度,且算法简单,易于实现。仿真表明,该算法能保证较高的跟踪效果。     

Decentralized model reference adaptive sliding mode control based on fuzzy model

1.INTRODUCTIONIn recent years,decentralized control of interconnect-ed systems has become an i mportant and challengingtopic[1~3].However,it is usually difficult to modelthe systemexactly due to the complex real environ-ment.In the past several years,active research hasbeen carried out in controller design based on univer-sal approxi mators,such as fuzzy control and neuralnetwork control[4~6].For a class of SISO nonlinearsystems,adaptive fuzzy control approaches were pro-posed based on …     

多变量非线性系统的直接自适应模糊预测控制

对一类多变量非线性系统提出了直接自适应模糊预测控制方法,此方法首先对被控对象提出了线性时变子模型加非线性子模型的预测模型,然后直接利用模糊系统设计预测控制器,并基于时变增益自适应律对控制器中的未知向量和逼近误差估计值进行自适应调整。证明了此方法可使跟踪误差收敛到原点的一个邻域内,仿真结果验证了此方法的有效性。     

基于遗传预估策略的智能主动队列管理

针对TCP传输过程中的典型时滞特性,提出了一种智能主动队列管理算法.该算法以自学习预估机制模型为核心来克服大时滞特征对网络稳定性能的影响,拥塞控制系统以两条信息通道分别实现模型补偿和预测控制功能.模型补偿通道采用了Smith预估嚣实现对网络时滞特征的动态补偿,并进一步设计迭代进化算法实现对Smith预估模型未建模特征的估计过程.预测控制通道采用基于神经网络的PID智能丢弃算法,通过神经网络的学习预测功能自适应调整预测控制通道的控制行为.通过仿真研究表明了提出的控制方法显著提高了拥塞控制机制的稳定性能和自适应性能.     

非完整移动机器人的自适应滑模轨迹跟踪控制

针对动力学模型描述的非完整移动机器人系统，研究了其在未知参数和不确定性干扰下的轨迹跟踪控制问题，基于反演技术和自适应滑模控制的思想设计了具有全局渐近稳定的轨迹跟踪控制律。谊控制律将系统分解为低阶子系统来处理，利用中间虚拟控制量和部分Lyapunov函数简化了控制器设计，并具有直观的稳定性分析．满足了移动机器人的轨迹跟踪要求，且具有设计方法简单、鲁棒性强的特点。仿真结果验证了所设计控制器的有效性和正确性。     

Neural network based adaptive sliding mode control of uncertain nonlinear systems

The purpose of this paper is the design of neural network-based adaptive sliding mode controller for uncertain unknown nonlinear systems. A special architecture adaptive neural network, with hyperbolic tangent activation functions, is used to emulate the equivalent and switching control terms of the classic sliding mode control (SMC). Lyapunov stability theory is used to guarantee a uniform ultimate boundedness property for the tracking error, as well as of all other signals in the closed loop. In addition to keeping the stability and robustness properties of the SMC, the neural network-based adaptive sliding mode controller exhibits perfect rejection of faults arising during the system operating. Simulation studies are used to illustrate and clarify the theoretical results.     

不确定非线性系统的鲁棒自适应跟踪简化算法

传统的Backstepping自适应控制方法需要对虚拟控制律进行求导,从而导致“计算复杂性膨胀”。动态平面控制技术能够克服这一缺陷。将这一技术扩展到一类具有参数严格反馈形式的不确定非线性系统输出跟踪,这类系统同时包含线性参数和未知非线性函数两种不确定性。所设计的控制算法比现有算法大大简化,解决了“计算复杂性膨胀”问题;运用Lyapunov理论证明了闭环系统一致最终有界,仿真结果表明了算法的有效性。     

基于强跟踪滤波器的改进非线性自适应观测器

对基于强跟踪滤波器的非线性自适应观测器(nonlinearadaptiveobserver,NAO)的收敛性进行了分析,给出了NAO局部渐近收敛的充分条件。提出了一种改进非线性自适应观测器(modifiednonlinearadaptiveobserver,MNAO)算法。MNAO在具有强跟踪特性的同时对输出测量中的坏数据有较强的鲁棒性。为了降低对初始误差的敏感性,采用一种强跟踪扩展卡尔曼观测器算法启动MNAO。数值仿真示例显示了本方法的有效性。     

一类非线性系统的自适应模型跟随控制

讨论了一类非线性系统的自适应模型跟随控制问题。首先给出了系统的一般描述,然后研究了该系统模型跟随控制的存在条件，最后讨论了如何设计前馈控制和反馈控制矩阵的迭代调节律,使得系统输出能够快速地稳定地跟随参考模型输出。仿真结果表明了这一控制方案具有良好的非线性跟随效果。     

一类模糊时滞系统自适应跟踪控制与仿真

基于T-S模糊模型和变结构控制策略,研究了一类带有参数不确定项的模糊时滞系统自适应输出跟踪问题。首先利用变结构控制理论选择滑动模,根据李雅普诺夫方法,提出了一种自适应变结构控制策略。利用自适应策略的目的在于克服扰动的未知上界,使设计的控制器满足可达条件。该方法确保系统的运动轨迹在有限的时间内到达滑模面并一直保持在滑模面上。其次根据ISS理论和LMI方法研究了系统状态全局有界的充分条件。最后,通过仿真实例验证了所提方法的正确性和有效性。