基于system gain的驾驶性能分析

基于大数据统计得到的系统增益理论曲线分析车辆的驾驶性能,运用软件与实车测试的综合分析方式,同时采用主观评价的直观评价方式,验证此概念的合理性,以达到节省实车测试验证次数,节约汽车中期研发阶段的开发成本的目的。

Anti-windup Compensator Gain Design for Time-delay Systems with Constraints

Systems that are subject to both time-delay in state and input saturation are considered. We synthesize the anti-windup gain to enlarge the estimation of domain of attraction while guaranteeing the stability of the closed-loop system. An ellipsoid and a polyhedral set are used to bound the state of the system, which make a new sector condition valid. Other than an iterative algorithm, a direct designing algorithm is derived to compute the anti-windup compensator gain, which reduces the conservatism greatly. We analyze the delay-independent and delay-dependent cases, respectively. Finally, an optimization algorithm in the form of LMIs is constructed to compute the compensator gain which maximizes the estimation of domain of attraction. Numerical examples are presented to demonstrate the effectiveness of our approach.

Noticeable positive Doppler effect on optical bistability in an N-type active Raman gain atomic system

We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.

Anti-synchronization of a new hyperchaotic system via small-gain theorem

Based on the small-gain theorem, the anti-synchronization between two identical new hyperchaotic systems is investigated, moreover, the general sufficient conditions to achieve anti-synchronization between the new hyperchaotic system and the new hyperchaotic Lorenz system are obtained via small-gain theorem. Numerical simulations are performed to verify and illustrate the analytical results.

Peak-to-Peak Gain Minimization for Uncertain Linear Discrete Systems： A Matrix Inequality Approach

为不明确的线性分离系统的一个班的 peak-to-peak 获得最小化的一条矩阵不平等途径被学习。我们最小化 * 是导致的 L 标准上的最好的上面的界限的 -norm, 由与逃避不了的椭圆体围住可达到的集合获得了，而不是直接最小化导致的 L 标准。基于这个想法，柔韧的 peak-to-peak 获得最小化的问题和控制器合成被归结为解决一套矩阵不平等的可行性问题。一个数字例子被用来表明介绍方法的可行性和有效性。

Fuzzy Adaptive Control of Stochastic Nonlinear Systems with Unknown Virtual Control Gain Function

The problem of track control is studied for a class of strict-feedback stochastic nonlinear systems in which unknown virtual control gain function is the main feature. First, the so-called stochastic LaSalle theory is extended to some extent, and accordingly, the results of global ultimate boundedness for stochastic nonlinear systems are developed. Next, a new design scheme of fuzzy adaptive control is proposed. The advantage of it is that it does not require priori knowledge of virtual control gain function sign, which is usually demanded in many designs. At the same time, the track performance of closed-loop systems is improved by adaptive modifying the estimated error upper bound. By theoretical analysis, the signals of closed-loop systems are globally ultimately bounded in probability and the track error converges to a small residual set around the origin in 4th-power expectation.

Transportation-cyber-physical-systems-oriented engine cylinder pressure estimation using high gain observer

In transportation cyber-physical-systems （T-CPS）, vehicle-to-vehicle （V2V） communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrastructures, and engine cylinder pressure is significant for engine diagnosis on-line and torque control within the information exchange process under V2V communications. However, the parametric uncertainties caused from measurement noise in T-CPS lead to the dynamic performance deterioration of the engine cylinder pressure estimation. Considering the high accuracy requirement under V2V communications, a high gain observer based on the engine dynamic model is designed to improve the accuracy of pressure estimation. Then, the analyses about convergence, converge speed and stability of the corresponding error model are conducted using the Laplace and Lyapunov method. Finally, results from combination of Simulink with GT- Power based numerical experiments and comparisons demonstrate the effectiveness of the proposed approach with respect to robustness and accuracy.

Fault diagnosis based on high-gain observer with an update law for a class of nonlinear systems

In this paper,by using the well-known high-gain observer design,an update law for the gain and an adaptive estimation of parameters,a new method of fault diagnosis for a class of nonlinear systems is presented.Without resort to any transformation for the parameters,the estimation errors of the states and the parameters are guaranteed to be globally exponentially convergent by a persistent excitation condition.Compared to the existing results,it can be applied to nonlinear systems with nonlinear terms admitting an incremental rate depending on the measured output.A case study further verifies the validity of the proposed research.

Consensus Control With a Constant Gain for Discrete-time Binary-valued Multi-agent Systems Based on a Projected Empirical Measure Method

This paper studies the consensus control of multiagent systems with binary-valued observations.An algorithm alternating estimation and control is proposed.Each agent estimates the states of its neighbors based on a projected empirical measure method for a holding time.Based on the estimates,each agent designs the consensus control with a constant gain at some skipping time.The states of the system are updated by the designed control,and the estimation and control design will be repeated.For the estimation,the projected empirical measure method is proposed for the binary-valued observations.The algorithm can ensure the uniform boundedness of the estimates and the mean square error of the estimation is proved to be at the order of the reciprocal of the holding time(the same order as that in the case of accurate outputs).For the consensus control,a constant gain is designed instead of the stochastic approximation based gain in the existing literature for binary-valued observations.And,there is no need to make modification for control since the uniform boundedness of the estimates ensures the uniform boundedness of the agents’states.Finally,the systems updated by the designed control are proved to achieve consensus and the consensus speed is faster than that in the existing literature.Simulations are given to demonstrate the theoretical results.

Output feedback adaptive control of multivariable nonlinear systems using Nussbaum gain method

A new output feedback adaptive control scheme for multi-input and multi-output nonlinear systems with parametric uncertainty is presented based on the Nussbaum gain method and the backstepping approach. The high frequency gain matrix of the linear part of the system is not necessarily positive definite, but can be transformed into a lower or upper triangular matrix whose signs of diagonal dements are unknown. The new required condition for the high fi＇equency gain matrix can be easily checked for certain plants so that the proposed method is widely applicable. The global stability of the closed loop systems is guaranteed through this control scheme, at the same time the tracking error converges to zero.

Adaptive Fuzzy Backstepping Output Feedback Control of Nonlinear Time-delay Systems with Unknown High-frequency Gain Sign

In this paper, an adaptive fuzzy robust feedback control approach is proposed for a class of single-input and singleoutput （SISO） strict-feedback nonlinear systems with unknown nonlinear functions, time delays, unknown high-frequency gain sign, and without the measurements of the states. In the backstepping recursive design, fuzzy logic systems are employed to approximate the unknown smooth nonlinear functions, K-filters is designed to estimate the unmeasured states, and Nussbaum gain functions are introduced to solve the problem of unknown sign of high-frequency gain. By combining adaptive fuzzy control theory and adaptive backstepping design, a stable adaptive fuzzy output feedback control scheme is developed. It has been proven that the proposed adaptive fuzzy robust control approach can guarantee that all the signals of the closed-loop system are uniformly ultimately bounded and the tracking error can converge to a small neighborhood of the origin by appropriately choosing design parameters. Simulation results have shown the effectiveness of the proposed method.

乡村青年教师获得感指标体系构建研究

作为乡村教师队伍的后备力量与持续动力,乡村青年教师承担着振兴乡村教育发展的重任。切实的获得感是增进乡村教师职业吸引力、坚定乡村青年教师教育信念的关键因素,也是建设高质量乡村教师队伍的根本保障。研究通过修正德尔菲法与层次分析法建构了包含“生存保障获得感”“关系归属获得感”“自我发展获得感”3个一级指标、“物质经济获得感”“政策保障获得感”“社会交往获得感”“公共文化获得感”“社会声望获得感”“专业成长获得感”“职业成就获得感”7个二级指标及28个相应三级指标的乡村青年教师获得感指标体系。在此基础上提出乡村青年教师获得感提升理路:完善物质保障,推进差异化教师激励政策;整合关系归属,锚定人性化社会需要;保持自我发展,合理规划未来预期。

一种含扰动离散非线性系统状态观测器的设计方法

针对一类含扰动的非线性离散系统,讨论了系统状态观测器的设计问题,给出了一种离散系统状态观测器的设计方法,并将该方法应用到奇异系统观测器设计中。首先,根据李雅普诺夫稳定性理论,得到离散系统在不含外部扰动下观测器增益矩阵存在的充分条件;其次,考虑到离散系统的扰动项,针对系统中的外部扰动在李雅普诺夫函数设计中纳入性能指标,得到含扰动情况下离散系统观测器增益矩阵存在的充分条件,该方法可以通过设置性能指标减弱扰动对系统状态估计的影响,同时也有利于增益矩阵的设计与求解;最后,将非线性离散系统观测器的设计方法推广到奇异系统中,从而使该方法更具一般性。利用三个数值算例对所提方法进行了检验,仿真结果表明了文中所提方法的可行性与有效性。

the phase-dependent gain without inversion in a Doppler broadened open four-level system

It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence （SGC）, the gain without inversion （GWI） is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate （R0） and the ratio （S） of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI. GWI first increases and then decreases with R0 increasing; in a certain value range of S, GWI increases monotonically with S increasing; by adjusting the values of R0 and S, in an open system a much larger GWI can be obtained than in the corresponding closed system [2011 Phys. Rev. A 83 043805]. The modulation effects of R0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case, GWI in the co-propagating case is much larger than that in the counter-propagating case.

一种含扰动非线性离散系统的故障观测器设计方法

针对一类含扰动、传感器故障和执行器故障的非线性离散系统,提出了一种新型的故障观测器设计方法,该方法既考虑到了故障的类型,又考虑到了故障估计误差的收敛速度,故障估计方法适用性更强。首先,构造出含系统状态和传感器故障的增广向量,得到一个等价的广义系统;其次,考虑到系统中的执行器故障及故障估计的速度,构建同时含系统状态、执行器故障和传感器故障的故障观测器,并给出故障观测器存在的充分条件;最后,通过某飞机的纵向运动系统等非线性离散系统模型,对增广状态向量进行鲁棒估计,故障估计结果验证了该方法的优越性。

基于LSTM的多维度进程异常行为检测

恶意进程是威胁系统安全的一个重要因素,通过检测系统调用序列能有效发现恶意进程。不同的进程类型产生的调用序列会出现长度等方面的差异,因此单一化的检测方法无法在多种进程类型的检测上保持较高的准确率。针对这个问题,提出了基于长短时记忆(Long Short-Term Memory,LSTM)神经网络的多维度进程异常行为检测方法,在时间维度的基础上通过N-gram算法增加数据的信息维度,在多维数据形式中选取特征表现更好的维度进行异常判决。在UNM和ADFA-LD数据集上的实验结果表明,多维度的方法可以丰富调用序列的特征表现,以此减小不同进程类型的特征差异,且在多种进程类型下均有较好检测效果,使检测泛化能力得到提升。该方法在ADFA-LD数据集上与常用机器学习模型相比,准确率比支持向量机(Support Vector Machine,SVM)高11个百分点且误报率降低了70%,且相对于其他模型,检测效果均有所提升。

基于事件触发的预设时间航天器轨迹跟踪控制

针对通信受限条件下的航天器轨迹跟踪问题,提出了一种基于事件触发的预设时间控制算法。为了满足不同任务场景下对航天器快速性的要求,本文设计了一种预设时间轨迹跟踪控制算法。结合反步控制理论及预设时间动态增益,最终实现轨迹跟踪系统的预设时间收敛。作为一种典型的网络化控制系统,航天器在执行任务过程中可能会受到自身通信能力的限制,造成通信阻塞、时延和丢包等问题。为此,本文提出了一种基于动态参数的事件触发算法,在保证系统控制精度的同时,一定程度上避免了控制中心与航天器本体间不必要的通信资源消耗。相比于传统的静态事件触发算法,文中基于动态参数的事件触发算法在减少通信频率方面更具优势。通过理论分析和仿真实验验证所提控制算法的有效性。

基于ATSMC的破障武器随动系统控制研究

针对电动缸驱动的车载破障武器随动系统控制问题,提出了一种基于指数收敛的干扰观测器和反正切滑模控制器的方法。研究了电动缸传动时系统具有的非线性增益,推导了电动缸机构的变传动比和变负载力矩的公式。为了对随动系统进行位置和速度控制,根据多项式Terminal滑模控制器的思想,采用等效趋近律的方法,设计了反正切Terminal滑模控制器(ATSMC),其具有全局鲁棒性和有限时间可达的能力;为了对系统内部的不确定性和外部扰动进行观测和补偿,设计了一种基于指数收敛的干扰观测器。对控制系统进行仿真,结果表明,ATSMC具有更好的鲁棒性,提高了随动系统控制精度,缩短了响应时间;基于指数收敛的干扰观测器能较好地补偿系统运行中产生的各种扰动,降低了系统稳态误差。

Modulation of atomic exit and injection rates on the phase-dependent gain without inversion in a Doppler broadened open four-level system

It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate (R0) and the ratio (S) of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI. GWI first increases and then decreases with R0 increasing; in a certain value range of S, GWI increases monotonically with S increasing; by adjusting the values of R0 and S, in an open system a much larger GWI can be obtained than in the corresponding closed system [2011 Phys. Rev. A 83 043805]. The modulation effects of R0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case, GWI in the co-propagating case is much larger than that in the counter-propagating case.