利用非线性反馈控制悬架系统的混沌行为

基于磁流变减振器的汽车悬架系统具有明显的滞后非线性,这直接导致了系统存在分岔与混沌的可能性。分析了悬架系统在路面单频正弦激励下的受迫振动,揭示了该系统存在混沌运动可能性。在此基础上,利用非线性反馈控制方法对这类混沌行为进行了控制,并采用Melnikov方法确定该控制系统的增益系数。     

任意概率不确定情形下的电动汽车悬置系统固有特性分析

针对电动汽车动力总成悬置系统 （Powertrain Mounting System，PMS） 参数可能被处理为不同类型概率变量的情形，提出了一种基于任意多项式混沌 （Arbitrary Polynomial Chaos，APC） 展开和最大熵原理 （Maximum Entropy Principle，MEP） 的电动汽车 PMS固有特性不确定性分析方法。采用概率模型描述任意概率不确定情形下的 PMS参数，通过APC展开获得任意概率不确定情形下PMS固有特性不确定性响应的前几阶统计矩，通过MEP拟合不确定性响应的概率密度函数 （Probability Density Function，PDF） 和累积分布函数 （Cumulative Distribution Function，CDF） 等信息，通过算例分析了5种概率不确定情形下的电动汽车PMS固有特性响应。分析结果表明，以蒙特卡洛法作为参考，所提出的方法可有效地分析不同概率不确定情形下的PMS固有特性响应，分析具有较高的计算精度和计算效率，能进一步获得响应满足设计要求的可靠度。     

Stochastic wave spectra estimation (SWSE) based on response surface methodology considering uncertainty in transfer functions of a ship

In this paper, a new wave spectra estimation method is proposed in which the frequency domain wave estimation method (FDWE) is extended into a probabilistic analytical framework in order to estimate the encountered sea states involving uncertainty in transfer functions of a ship. The proposed method, named the Stochastic Wave Spectra Estimation (SWSE), makes use of an Hermite polynomial chaos expansion (PCE) to represent the uncertainty in the transfer functions and the response surfaces. The method involves a mathematical formulation where an extension of the deterministic FDWE concept to the space of random variables is made. The proposed method can accurately and easily estimate the encountered wave spectra based on ship response measurements accounting for uncertainty in the transfer functions. In this paper, numerical and experimental investigations of the proposed SWSE are made, where the uncertainties in the transfer functions of heave and pitch motions of a containership are taken into account. The validity of the SWSE is demonstrated by comparison to results of uncertainty analyses through the Monte-Carlo simulations (MCS).