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针对车辆行驶下的路面附着系数估计问题,提出了扩展卡尔曼滤波算法(EKF,Extended Kalman Filter)与径向基神经网络(RBF,Radial Basis Functionneural network)相融合。通过扩展卡尔曼滤波算法得出路面附着系数估计所需要的车辆状态参数,结合轮速等直接数据采用径向基神经网络对路面附着系数进行估计。神经网络的训练样本通过Carsim/Simulink收集不同行驶工况,并采用差值寻优的方法对径向基神经网络算法中的决定系数进行优化。基于双移线工况验证了该算法在路面附着系数估计上具有较高的精准度。 相似文献
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The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model.But it is not enough to use this kind of model for practical applications.In this paper,based on considering the influence of factors such as,seat and passengers a MDOF(multi-degree-of-freedom)model describing the vehicle motion is set up.The MODF model,which is 8DOF of four independent suspensions and four wheel tracks,is more applicable by comparison of its analysis result with some conventional vehicle models.Therefore,it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration.Based on the derived 8DOF odel,a controller is designed by using LQ(linear quadratic)control theory,and the appropriate control scheme is selected by testing various performance indexes.Computer simulation 8is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density(PSD).Vibrations corresponding to ride comfort are derived under the foregoing road disturbances.The response results for uncontrolled and controlled system are compared.The response of vehicle vibration is greatly suppressed and quickly damped.which testifies the effect of the active suspenson.The results achieved for various controllers are compared to invesigate the influence of different control schemes on the control effect. 相似文献
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Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time
localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model
is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor
node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of
the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF
algorithm. 相似文献
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This paper focuses mainly on the stability analysis of two-lane traffic flow with lateral friction, which may be caused by irregular driving behavior or poorly visible road markings, and also attempts to reveal the formation mechanism of traffic jams. Firstly, a two-lane optimal velocity (OV) model without control signals is proposed and its stability condition is obtained from the viewpoint of control theory. Then delayed-feedback control signals composed of distance headway information from both lanes are added to each vehicle and a vehicular control system is designed to suppress the traffic jams. Lane change behaviors are also incorporated into the two-lane OV model and the corresponding information about distance headway and feedback signals is revised. Finally, the results of numerical experiments are shown to verify that when the stability condition is not met, the position disturbances and resulting lane change behaviors do indeed deteriorate traffic performance and cause serious traffic jams. However, once the proper delayed-feedback control signals are implemented, the traffic jams can be suppressed efficiently. 相似文献
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Equivalent circuit model-based state-of-charge (SOC) estimation has been widely studied for power lithium-ion batteries. An appropriate relaxation period to measure the open-circuit voltage (OCV) should be investigated to both ensure good SOC estimation accuracy and improve OCV test efficiency. Based on a battery circuit model, an SOC estimator in the combination of recursive least squares (RLS) and the extended Kalman filter is used to mitigate the error voltage between the measurement and real values of the battery OCV. To reduce the iterative computation complexity, a two-stage RLS approach is developed to identify the model parameters, the battery circuit of which is divided into two simple circuits. Then, the measurement values of the OCV at varying relaxation periods and three temperatures are sampled to establish the relationships between SOC and OCV for the developed SOC estimator. Lastly, dynamic stress test and federal test procedure drive cycles are used to validate the model-based SOC estimation method. Results show that the relationships between SOC and OCV at a short relaxation time, such as 5 min, can also drive the SOC estimator to produce a good performance. 相似文献
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为了深入研究路面养护中抗滑界限与公路设计中制动距离限值间的关系,提出了考虑路面摩擦特性时确定制动距离的方法.基于理论流体动力学和基本力学原理,考虑轮胎类型、水膜厚度、路表特性、行车速度等因素,建立了稳态滚动轮胎的有限元模型;运用该模型计算了不同运行条件下的制动距离;通过比较分别满足养护和设计界限的制动距离,确定了路表允... 相似文献
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Steffen Nestler 《Structural equation modeling》2013,20(3):461-473
This article applies Bollen’s (1996) 2-stage least squares/instrumental variables (2SLS/IV) approach for estimating the parameters in an unconditional and a conditional second-order latent growth model (LGM). First, the 2SLS/IV approach for the estimation of the means and the path coefficients in a second-order LGM is derived. An empirical example is then used to show that 2SLS/IV yields estimates that are similar to maximum likelihood (ML) in the estimation of a conditional second-order LGM. Three subsequent simulation studies are then presented to show that the new approach is as accurate as ML and that it is more robust against misspecifications of the growth trajectory than ML. Together, these results suggest that 2SLS/IV should be considered as an alternative to the commonly applied ML estimator. 相似文献
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On the basis of analyzing the system constitution of vehicle semi-active suspension,a 4-DOF(degree of freedom)dynamic model is established.A tunable fuzzy logic controller is designed by using without quantification method and taking into account the uncertainty,nonlinearity and complexity of parameters for a vehicle suspension system.Simulation to test the performance of this controller is performed under random excitations and definite disturbances of a C grade road,and the effects of time delay and changes of system parameters on the vehicle suspension system are researched.The numerical simulation shows that the performance of the designed tunable fuzzy logic controller is effective,stable and reliable. 相似文献
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为改善汽车的平顺性,将模糊控制算法引入半主动悬架,对其控制系统进行研究。首先以四自由度汽车半主动悬架为研究对象建立了其数学模型与仿真模型;在Matlab中利用模糊逻辑工具箱Fuzzy Toolbox设计了半主动悬架模糊控制器;在此基础上,利用Matlab/Simulink软件搭建半主动悬架模糊控制系统并在白噪声路面及阶跃路面信号激励下进行仿真试验。实验结果表明,所设计的模糊控制器可以有效改善汽车的平顺性并提高汽车的行驶安全性。 相似文献
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This paper presents the development of a proportional-integral-derivative (PID)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PID hydraulic actuator force control loop, in combination with an outer PID suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains. 相似文献
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对汽车垂直方向振动的分析,对汽车的元件进行合理的简化,建立8自由度动力学模型,给出了模型的质量矩阵、刚度矩阵和阻尼矩阵.根据实际的车型,按比例缩小设计出汽车的振动模拟装置.然后通过凸轮实现路面的模拟输入,利用空气弹簧模拟汽车的内部弹簧元件.根据系统的拉格朗日方程,求解系统8自由度动力学运动微分方程,采用龙格-库塔（Runge-Kutta）法,在Matlab的环境下进行汽车运动求解,得到汽车在不同路面行驶的振动规律. 相似文献
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龚鹏飞 《实验室研究与探索》2021,(1):97-100
为验证不同种类的交通事故现场处置车辆在不同的停放方式下对交通事故现场的防御效果,采用PC-Crash 12.0中文版软件设计了一种仿真实验。通过模拟误闯入交通事故处置现场的车辆与防御车辆的碰撞,以防御车辆被误闯入车辆撞击后沿道路前进方向运行的距离作为防御效果的评价指标,运行的距离越短,防御效果越好。仿真结果表明:大型车辆的防御效果要明显优于小型车辆;当防御车辆一定时,最佳的防御角度随误闯入车辆的速度增加而减少;当误闯入车辆的速度位于中速(50 km/h)时,防御车辆与道路前进方向的夹角在30°左右时防御效果最佳。 相似文献
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WU Yun LUO Han-wen DING Ming YAN Chong-guang 《浙江大学学报(A卷英文版)》2006,7(12):2104-2109
INTRODUCTION Orthogonal frequency division multiplexing (OFDM) has become a promising technology for future wireless communication systems (Kim et al., 2003; 3GPP TSG-RAN-1.TR, 2004) due to its ability to transform a wideband frequency selective channel to a set of parallel flat-fading narrow-band channels, which substantially simplifies the channel equaliza- tion problem. However, a critical weakness of OFDM is its sensitivity to carrier frequency offset (CFO) since it can only t… 相似文献
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The least means squares (LMS) adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freedom vehicle suspension model, LMS adaptive controller was designed. The acceleration of the sprung mass,the dynamic tyre load between wheels and road,and the dynamic deflection between sprung mass and unsprung mass were determined as the evaluation targets of suspension performance. For LMS adaptive control suspension, compared with passive suspension, acceleration power spectral density of sprung mass acceleration under the road input model decreased 8-10 times in high frequency resonance band or low frequency resonance band. The simulation results show that LMS adaptive control is simple and remarkably effective. It further proves that the active control suspension system can improve both the riding comfort and handling safety in various operation conditions, and the method is fit for the active control of the suspension system. 相似文献
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Precise navigation for a 4WS mobile robot 总被引：1，自引：0，他引：1
何波 《浙江大学学报(A卷英文版)》2006,7(2):185-193
INTRODUCTION Precise navigation is being researched and ap- plied in various fields, especially for outdoor mobile robots (Wang et al., 1998; Lee, 1997; Iida et al., 2000), such as those used in cargo container trans- portation at seaport, in precision agriculture, military vehicles, etc. As we know, applied sensors and rele- vant data processing basically determine the accuracy of navigation. In our research, GPS and encoders are used as navigation sensors. As an absolute positioning s… 相似文献
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A new relative efficiency of parameter estimation for generalized Gauss-Markov linear model was proposed. Its lower bound was also derived. Its properties were explored in comparison with three currently very popular relative efficiencies. The new relative efficiency not only reflects sensitively the error and loss caused by the substitution of the least square estimator for the best linear unbiased estimator, but also overcomes the disadvantage of weak dependence on the design matrix. 相似文献