轿车动力总成NVH性能分析及悬置优化

主要对动力总成的NVH性能进行研究,特别是动力总成的振动。首先建立NVH的数学模型,进行性能的理论分析和仿真。在此基础上,利用能量解耦法的原理对其悬置系统进行优化,以改进动力总成的NVH性能。仿真结果表明,优化后的系统结构参数极大地降低了整车振动,提高了乘坐舒适性。     

城轨虚拟编组关键性能指标及技术探讨

列车虚拟编组技术能够实现车辆资源的高效灵活利用,是解决轨道交通客流时空分布不均衡问题的有效方法,已成为国内外的研究热点。既有研究借鉴了汽车编队追踪的思路,主要关注于列车稳定追踪的相关方法,未能完全适应轨道交通的实际需求。针对城市轨道交通(简称“城轨”)虚拟编组研究的需要,深入分析城轨列车运行的特征,在此基础上总结提出包括站台停车时间差等在内的城轨列车虚拟编组应符合的技术性能指标;其次,针对虚拟编组的技术特征,提出包括大小交路和Y型线路等适合列车虚拟编组的潜在应用场景,并对实现虚拟编组的关键技术及其原理进行介绍,可为城轨列车虚拟编组研究提供参考。     

水下平台进水下潜过程的稳定性控制

介绍了某型水下平台的压载水系统组成,分析了其进水下潜过程的工作特点,结合静力学原理对平台进行分析和建模。针对进水控制系统为MIMO型且存在多变量耦合,采用模糊解耦的方法进行解耦分析,提出了一种基于模糊控制算法的平台进水下潜过程稳定性控制方法。经Matlab仿真表明,这种控制方法能够满足平台自动进水下潜过程的稳定性以及快速性要求。最后,通过实际系统水下试验进一步验证其可靠性。     

动车组转向架簧间大质量部件(牵引电机)振动解耦技术方案

针对更高速度等级动车组转向架的簧间大质量部件(牵引电机)振动解耦技术进行了专题研究,分析了牵引电机的横向悬挂刚度和阻尼对转向架动力学性能的影响。结果表明,让牵引电机和构架在横向方向解耦到一定程度,即适当降低牵引电机的横向悬挂刚度和阻尼,可提高转向架的蛇行临界速度。为达到较高蛇行临界速度所需的横向悬挂刚度和阻尼,提出了一种高速转向架牵引电机横向解耦弹性架悬机构技术方案。该方案能将电机的横向悬挂刚度降低至0.34 MN/m,可实现电机与构架的横向低刚度解耦。     

The Force-Angle Measure of Tipover Stability Margin for Mobile Manipulators

Mobile manipulators operating in field environments will be required to apply large forces, or manipulate large loads, and to perform such tasks on uneven terrain which may cause the system to approach, or reach, a dangerous tipover instability. To avoid tipover in an automatic system, or to provide a human operator with an indication of proximity to tipover, it is necessary to define a measure of available stability margin. This work presents a new tipover stability measure (the Force-Angle stability measure) which has a simple geometric interpretation, is easily computed, and is sensitive to changes in Center of Mass height. The proposed metric is applicable to systems subject to inertial and external forces, operating over even or uneven terrains. Requirements for computation and implementation of the measure are described, and several different categories of application of the measure are presented along with useful normalizations. Performance of the Force-Angle measure is demonstrated and compared with that of other stability margin measures using a forestry vehicle simulation. Results show the importance of considering both center-of-mass height and system heaviness, and confirm the effectiveness of the Force-Angle measure in monitoring the tipover stability margin.     

Asymptotic sideslip angle and yaw rate decoupling control in four-wheel steering vehicles

This paper shows that, for a four-wheel steering vehicle, a proportional-integral (PI) active front steering control and a PI active rear steering control from the yaw rate error together with an additive feedforward reference signal for the vehicle sideslip angle can asymptotically decouple the lateral velocity and the yaw rate dynamics; that is the control can set arbitrary steady state values for lateral speed and yaw rate at any longitudinal speed. Moreover, the PI controls can suppress oscillatory behaviours by assigning real stable eigenvalues to a widely used linearised model of the vehicle steering dynamics for any value of longitudinal speed in understeering vehicles. In particular, the four PI control parameters are explicitly expressed in terms of the three real eigenvalues to be assigned. No lateral acceleration and no lateral speed measurements are required. The controlled system maintains the well-known advantages of both front and rear active steering controls: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres and improved manoeuvrability. In particular, zero lateral speed may be asymptotically achieved while controlling the yaw rate: in this case comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced. Also zero yaw rate can be asymptotically achieved: in this case additional stable manoeuvres are obtained in obstacle avoidance. Several simulations, including step references and moose tests, are carried out on a standard small SUV CarSim model to explore the robustness with respect to unmodelled effects such as combined lateral and longitudinal tyre forces, pitch, roll and driver dynamics. The simulations confirm the decoupling between the lateral velocity and the yaw rate and show the advantages obtained by the proposed control: reduced lateral speed or reduced yaw rate, suppressed oscillations and new stable manoeuvres.     

Decoupling control in velocity-varying four-wheel steering vehicles with H∞ performance by longitudinal velocity and yaw rate feedback

In this paper, decoupling control with H_∞ performance for four-wheel steering (4WS) vehicles under varying longitudinal velocity is studied. A novel control scheme for a nonlinear model of three states, respectively, the longitudinal and lateral velocities, and yaw rate, is proposed to address this issue. The scheme is composed of two varying-parameter controllers designing problems for both longitudinal and lateral systems with coupling performance. Varying parameters of both these controllers depend only on longitudinal velocity. Controlled by these controllers, the longitudinal system is decoupled with lateral velocity and yaw rate, and the lateral system is input–output decoupling with H_∞ performance. In addition, feedback signals are the longitudinal velocity and yaw rate, hence observations or measurements of lateral velocity are not necessary. Simulations show that vehicles controlled by our scheme are input–output diagonal decoupling and execute very well while longitudinal velocity varies in a large range, coupling appears between longitudinal and lateral systems, and external disturbances do exist. In summary, this control scheme can improve handling characteristics, safety and comfort proved from theory to practice in this paper.     

基于免疫进化算法的发动机悬置系统稳健优化

在分析各种优化方法优缺点的基础上,建立发动机悬置系统六自由度动力模型。以六自由度方向的解耦率为最大优化目标,以各悬置点三向刚度为设计变量,选用免疫进化算法对发动机的悬置刚度参数进行优化,最后用Monte Carlo法对悬置系统进行稳健性分析。结果表明,优化解不仅能保证六自由度方向的高解耦率,还能保证悬置系统的稳健性,提高了产品的质量。     

风机系统改进及应用

风机系统应用于加压舱的空调系统,其功能为：船用加压舱进行正常工作过程中,利用风机系统对空调系统所产生的冷、热量与舱内空气进行有效交换,从而发挥空调系统应有的功能。本文主要介绍了某船加压舱空调系统中的风机系统的改进及应用。     

三电平PWM整流器半实物研究

本文基于三电平PWM整流器数学模型,采用状态反馈解耦后双闭环调节,辅以闭环观测器估计负载电流作前馈补偿的直接电流控制方案,同时通过辨识虚拟电网磁链,代替测量电网电压锁相作为控制中的定向矢量;针对三电平变换器中点电位平衡这一固有问题,采用准确解析计算使之平衡的零序电压分量,有效消除中点电位波动。最后搭建基于硬件在回路的半实物仿真实验装置,实现了低谐波双向能量传递,动静态性能良好,验证了控制策略的可行性和有效性。