用模糊模型在线辨识非线性系统

讨论用模糊方法实现非线性系统在线辨识问题.首先给出了简化的模糊规则表达 方法及其相应的自适应模糊推理,在此基础上给出了模糊模型参数在线辨识算法.最后对 非线性模型进行在线辨识,验证了本文提出的模糊模型及其在线辨识算法.     

一类非线性系统的稳定自适应控制

将一类非线性系统等价表示为时变线性系统, 在此基础上设计了自适应控制器. 利用小波网络直接辨识控制器参数. 从理论上证明了闭环系统的稳定性. 仿真结果表明了所提算法的有效性.     

非线性系统第一类模糊辨识器的设计及仿真

该文针对非线性系统的辨识问题,给出了第一类模糊辨识器的设计方案,该方案通过引入最优逼近误差的自适应律参数项,实时地调整参数来实现对非线性系统的辨识.采用此方法可使辨识器模型的输出很快收敛到真实系统,且辨识误差渐进收敛到零.该文根据此算法编写了便于仿真实现的MATLAB程序,且给出了此程序的解算流程图.最后对Rossler混沌系统的实例进行仿真,绘制了系统真实曲线和辨识器模型输出的估计值曲线,仿真结果说明了该方法在非线性系统辨识中的使用性和可行性.     

一类非线性系统参数辨识的新方法及其在生化发酵过程建模中的应用

本文运用按段多重Legendre多项式系(PMLP)[1],对一类参数可分离的非线性系统的 参数辨识给出一种新方法,所提算法具有精度高、计算量小、不必具有待辨识参数的先验知识 和可进行递推辨识等优点.该算法已成功地应用于只有少量实测数据的螺旋霉素菌体生长模 型的动力学参数的辨识.结果表明,此算法是该类非线性系统的一种有效和简便的参数辨识 方法.     

超声速流中二元机翼的颤振与极限环

以沉浮和俯仰自由度上具有间隙立方结构非线性的二元机翼模型为例,考虑系统的结构阻尼,建立了系统的非线性动力学方程.通过修正的三阶活塞理论模拟了超声速流中机翼的非定常气动力和气动力矩.引入无量纲参数将系统动力学方程无量纲化,通过数值模拟得到了二元机翼的时域响应和系统的相轨迹变化规律.通过系统的分岔图得到了无量纲参数和系统周...     

Euler-Bernoulli梁的非线性耗散边界反馈镇定

讨论具有非线性耗散边界反馈的Euler-Bernoulli梁的镇定问题.首先利用非线性半群 理论和能量摄动方法,证明了文中所给出的非线性耗散边界反馈控制可以镇定闭环系统的能量， 并导出了闭环系统的能量衰减速度.然后用例子说明文中所给出的非线性耗散边界反馈控制具 有较强的实用性.     

一类非线性系统参数辨识的新方法及其在生化发酵过程建模中的应用

本文运用按段多重Legendre多项式系(PMLP),对一类参数可分离的非线性系统的参数辨识给出一种新方法,所提算法具有精度高、计算量小、不必具有待辨识参数的先验知识和可进行递推辨识等优点。该算法已成功地应用于只有少量实测数据的螺旋霉素菌体生长模型的动力学参数的辨识。结果表明,此算法是该类非线性系统的一种有效和简便的参数辨识方法。     

非对称饱和扇形输入非线性系统的自适应模糊控制

针对一类具有未知不确定性,且状态不可测的非线性系统,考虑了输入端的饱和非对称扇区非线性特性影响,提出了系统模型未知情形下基于自适应模糊观测器的跟踪控制方案,采用Lyapunov-Krasovskii函数给出了滑模控制器参数和模糊逻辑的自适应调整律.所提方法不仅可保证闭环跟踪系统的稳定性,还削弱了传统方法对模型结构的依赖...     

未知参数非线性系统的自适应广义预测控制

研究非线性系统的稳定性和跟踪优化问题,针对未知参数非线性系统的参数辨识和输出跟踪问题,给出参数自适应广义预测控制方法,为使辨识模型能实时反映被控对象特性以及输出对设定值的跟踪有较高精度.提出将非线性系统转化为受控自回归滑动平均模型,根据输入输出数据辨识模型参数.采用广义预测控制滚动优化的策略得出最优控制律,将最优控制律作用于对象实现非线性系统的优化控制以及系统输出对设定值的跟踪控制.明显克服了自适应控制对模型精度要求高的缺陷且具有在线辨识,滚动优化的特点.最后,通过仿真实例验证了方法的有效性.     

利用调制函数法的模糊模型参数辨识

利用调制函数法辨识非线性连续系统的模糊模型参数.系统的动力学微分方程存在微分项,通过输入输出数据辨识模糊模型参数时不能忽略扰动的影响,因此辨识模糊模型参数比较困难.利用调制函数法可以消除微分项,通过无微分项的联立方程的求解容易进行模糊模型参数辨识.几个非线性连续系统的仿真实验验证了所设计的利用调制函数法的模糊模型参数辨识的正确性和有效性.     

Adaptive inverse compensation for actuator backlash with piecewise time-varying parameters

Existing adaptive inverse compensation methods for cancelling actuator backlash nonlinearity are all restricted to handle constant backlash parameters. In other words, when discontinuity and time variation as both ubiquitous phenomena in practical actuators exist, such inverse compensation methods are no longer applicable theoretically. So far, no result has been reported in addressing such an issue, regardless of its importance in practice. In this paper, we solve this problem by developing a new piecewise Lyapunov function analysis and using parameter projection adaptation mechanism. Based on such approaches, an adaptive inverse compensation control scheme is designed to compensate for piecewise time-varying actuator backlash nonlinearity. It is proved that all signals of closed-loop system are ensured bounded. Moreover, the steady-state error is bounded by an adjustable scalar approaching to zero arbitrarily. Simulation also illustrates the obtained theoretical results.     

具有间隙与补偿的分线性预测控制

本文通过引入间隙非线性预补偿器,讨论了具有间隙非线性特性及白噪声干扰的系统的预测控制问题。     

基于规则的阀门非线性特性离散时间仿真模型

在控制阀非线性特性研究中,Choudhury模型得到了广泛应用。但在输入信号突变较大时,模型输出的阀位与实际阀位之间存在一定的偏差。此外,Choudhury模型只考虑了阀门非线性特性中的黏滞特性,而没有考虑间隙特性。在详细分析产生偏差原因的基础上,通过总结阀门输出特性的规律,增设多个描述阀门状态的变量,提出了一种新的基于规则的阀门非线性特性离散时间仿真模型。该模型对Choudhury模型进行了改进,同时包括了间隙特性。仿真表明在各种输入信号情况下,阀门非线性模型能够详细描述阀门的物理实际。同时,该模型能够用于计算机控制系统中阀门非线性特性的模拟。     

A hybrid formulation and design of model predictive control for systems under actuator saturation and backlash

In this paper, we develop a hybrid design framework of model predictive controller (MPC) for multivariable systems that simultaneously and explicitly addresses the actuator saturation and backlash. The discrete characteristics of the actuator backlash allows us to mathematically express it as a set of mixed-integer linear inequalities constraint in the inputs. As a result, the constrained MPC design is formulated as solving a mixed-integer quadratic programming (MIQP) problem. Furthermore, the proposed MIQP-based design is applied only in the proximity of steady state operating points after locating the active backlash and providing the estimate of the backlash size. Simulation studies are presented to demonstrate how the hybrid MPC performs when applied to an industrial case study of fluid catalytic cracking unit. It is shown that in the presence of actuator saturation and backlash the closed-loop performance can be improved substantially when applying the hybrid method as compared to the traditional design approaches.     

Observer‐based compensation control of servo systems with backlash

For compensating backlash phenomenon in servo systems, the authors propose an observer method in this paper to estimate both system states and vibration torque before controller design. First, a systematic scheme is given to obtain plant parameters, which is very important in observing system states. This is a parameter estimation principle that gives a crude estimation and computes the differences between the crude and true values. As a result, the precise value of the parameters is obtained by adding together the crude value and the difference. Then, based on the precise estimated parameters, an extended state observer (ESO) is designed to obtain feedback and feedforward signals. Consequently, robust compensation control is achieved by designing an output feedback controller, consisting of a feedback term and a feedforward term. Finally, in order to validate the proposed approach, extensive experiments are performed on a practical servo system with backlash nonlinearity.     

考虑齿隙伺服系统的反步自适应模糊控制

针对具有未知参数和齿隙非线性的机电伺服系统,引入一种近似死区函数建立了系统的数学模型,给出了死区函数中参数的选取方法.用两个自适应模糊逻辑系统在线逼近机电伺服系统中的未知参数和非线性环节,从而避免了对每个未知参数推导自适应律.基于反步法设计了自适应模糊控制器,可抑制未知参数和齿隙非线性对系统性能的影响.采用Lyapunov方法证明了位置跟踪误差的指数收敛性.与PID控制方法对比的仿真实验表明,本文方法能够显著减小齿轮间传递力矩的振荡,并具有很好的控制精度和鲁棒性.     

具有间隙非线性系统的自适应控制*

本文对具有间隙非线性系统提出了自适应控制算法,在确定和随机情况下,控制算法都具有大范围渐近收敛性质,仿真结果表明该算法能有效地改善系统的控制性能。     

含间隙非线性的Wiener-Hammerstein系统复合补偿控制

针对含非对称间隙环节的Wiener-Hammerstein系统提出了一种新的由输出反馈和间隙动态逆补偿构成的复合控制方案.首先应用参数化分段线性表达式设计了未知参数的整体估计模型,可同时估计线性参数和间隙的特征参数,然后提出了一种新的误差有界的间隙动态逆模型,该模型可使得驱动信号能在间隙的不同线性段之间快速切换,在此基础上设计了鲁棒补偿控制律,同时对输入线性环节采用输出反馈控制构建了复合控制器,通过李亚普诺夫方法证明了闭环系统的稳定性.带减速器的单电机伺服系统模型的仿真结果表明该方法在跟踪精度良好的同时可使系统动态响应满足要求.     

Recursive identification for dynamic systems with backlash

A recursive algorithm for identification of nonlinear dynamic systems with backlash is proposed in this paper. In this method, the backlash, which is a non‐smooth function, is decomposed into a combination of a group of piecewise linearized models so that all the parameters of the backlash can be estimated separately. Moreover, the model of the backlash is embedded into a Hammerstein‐type model. Thus, a pseudo‐Hammerstein model with backlash is constructed. The estimation of the parameters for such a non‐smooth nonlinear system can be implemented through a so‐called recursive general identification algorithm (RGIA). Then, the corresponding convergence analysis of the RGIA for the model with backlash is also investigated. After that, two examples are presented to show the performance of the proposed method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society