车辆动态数学模型辅助的惯性导航系统

提出了一种利用车辆的动态数学模型改善车载低成本惯性导航系统精度的方法.通过车辆的运动学模型和非完整约束条件得到虚拟的位置和速度观测量,与前向速度一起辅助惯性导航系统,惯性导航系统修正后的方位角又用来改善车辆的运动学数学模型.利用解析分析和协方差仿真方法研究了该组合导航系统的可观测性.理论分析和仿真结果都证明了通过车辆动态数学模型的辅助,低成本惯性导航系统的精度可以得到改善.该方法可作为当全球定位系统(GPS)暂停工作时的一种备份导航系统,在较长时间内限制惯性导航系统的误差。

基于偏振光辅助定向的车辆自主式导航方法研究

针对车载惯性导航系统运动学辅助算法中,航向角误差发散,无法长时间得到高精度、高可靠性导航参数的问题,提出一种基于大气偏振光分布规律高精度定向的运动学辅助惯导精度提高算法。通过车载偏振光传感器系统测量解算获得的航向角信息和车辆动态数学模型提供的虚拟位置与速度观测量,与惯性导航系统的输出一起,利用多源信息融合技术进行导航参数的滤波估计,结果能实时反馈校正惯性导航系统和车辆动态数学模型。通过计算机仿真与分析表明,该改进的惯性导航系统辅助方法能够有效抑制航向角误差发散,定位精度较纯惯导及传统惯导运动学辅助方法显著增强,且对最终实现陆地作战车辆精确可靠的自主导航定位具有一定的工程应用价值。

平面设计中横向力系数与舒适度关系的探讨

道路路线设计规范在定义极限圆曲线半径时,把横向力系数作为衡量车辆稳定性的一个重要因素。通过车辆动态模型仿真车辆在同一圆曲线不同横坡上行驶,表明乘客的舒适度感受与横向力系数是不等同的,车辆轮胎与地面的横向力系数随着超高横坡的变化而变化。仿真结果发现比现行设计规范中所设超高极限圆半径值增加约10%才能满足车辆最不利轮胎处的横向力系数要求。

Dynamic behaviors of pretensioned cable AERORail structure

The AERORail, a new aerial transport platform, was chosen as the object of this work. Following a review of the literature on static behaviors, model tests on the basic dynamic mechanical characteristics were conducted. A series of 90 tests were completed with different factors, including tension force, vehicle load and vehicle speed. With regard to the proper tension and vehicle load, at a certain speed range, the tension increments of the rail's cable were proved relatively small. It can be assumed that the change of tension is small and can be reasonably ignored when the tension of an entire span is under a dynamic load. When the tension reaches a certain range, the calculation of the cable track structure using classical cable theory is acceptable. The tests prove that the average maximum dynamic amplification factor of the deflection is small, generally no more than 1.2. However, when the vehicle speed reaches a certain value, the amplified factor will reach 2.0. If the moving loads increase, the dynamic amplification factor of dynamic deflection will also increase. The tension will change the rigidity of the structure and the vibration frequency; furthermore, the resonance speed will change at a certain tension. The vibration is noticeable when vehicles pass through at the resonance speed, and this negative impact on driving comfort requires the right velocity to avoid the resonance. The results demonstrate that more design details are required for the AERORail structure.

Practical Model for Real Structure and Performance of Heavy Vehicles

In this paper, a new practical model for real heavy vehicle structure is developed to investigate dynamic responses under steering/acceleration or braking maneuvers. The generalized six DoFs （degrees-of-freedom） nonlinear vehicle model M1 including longitudinal, lateral, yaw, vertical, roll and pitch dynamics is validated using the measured data reported in different studies. This model takes the CG （center of gravity） of sprung mass, unsprung mass and total vehicle mass into account. Based on this model, the effects of the inertia parameters on the vehicle dynamic responses are investigated for more comprehensive assessments of the model structure. Another nonlinear vehicle model 342 derived from M1 which assumes that the vehicle has a single CG as reported in literature is also developed. The dynamic responses of the vehicle model Mj are compared with those of the model M2 to demonstrate the performance potential of the proposed nonlinear model. The results of dynamic responses with the nonlinear vehicle model MI suggest that the model could offer considerable potential in realizing enhanced ride and handling performance, as well as improved roll and pitch properties in a flexible manner.

Damage evolution and dynamic response of cement asphalt mortar layer of slab track under vehicle dynamic load

The damage evolution and dynamic performance of a cement asphalt(CA)mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper.Initially,a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory.In this model,the strength of the CA mortar elements is treated as a random variable,which follows the Weibull distribution.The inclusion of strain rate dependence affords considering its influence on the damage development and the transition between viscosity and elasticity.Comparisons with experimental data support the reliability of the model.A three-dimensional finite element(FE)model of a slab track is then created with the commercial software ABAQUS,where the devised model for the CA mortar is implemented as a user-defined material subroutine.Finally,a vertical vehicle model is coupled with the FE model of the slab track,through the wheel-rail contact forces,based on the nonlinear Hertzian contact theory.The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction.The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load.The dynamic compressive strain,the strain rate,and the induced damage increase significantly with an increase in the initial damage,whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage.Also,it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer.

Maneuver control of the hypersonic gliding vehicle with a scissored pair of control moment gyros

A maneuver control approach using a scissored pair of control moment gyros is proposed to improve the penetration ability of a hypersonic gliding vehicle(HGV) with a relatively high lift-drag ratio. Then, a multivariable strong coupling nonlinear bank-toturn dynamical model is established for the case of lateral maneuvering of an HGV equipped with a scissored pair of control moment gyros. According to the requirement of coordinated turning of the HGV in a lateral maneuver, a decoupling controller based on feedback linearization and a linear quadratic optimal algorithm is designed. Finally, the large airspace maneuvering trajectories of the HGV including S-shaped, cycloid and spiral maneuvering modes are designed by applying overload control technology. Simulations demonstrate that the designed maneuvering trajectory significantly increases the airspace range and flexibility of the vehicle. The coordinated turn control system achieves an accurate and rapid tracking of the maneuvering trajectories in large airspace.

Vehicle height control of electronic air suspension system based on mixed logical dynamical modelling

Due to the coexistence and coupling of continuous variables and discrete events, the vehicle height adjustment process of electronic air suspension system can be regarded as a typical hybrid system. Therefore, the hybrid system theory was applied to design a novel vehicle height control strategy in this paper. A nonlinear mechanism model of the vehicle height adjustment system was established based on vehicle system dynamics and thermodynamic theory for variable-mass gas charge/discharge system. In order to model both the continuous/discrete dynamics of vehicle height adjustment process and the on-off statuses switching of solenoid valves, the framework of mixed logical dynamical(MLD) modelling was used. On the basis of the vehicle height adjustment control strategy, the MLD model of the adjustment process was built by introducing auxiliary logical variables and auxiliary continuous variables. Then, the co-simulation of the nonlinear mechanism model and the MLD model was conducted based on the compiling of HYSDEL. The simulation and experimental results show that the proposed control strategy can not only adjust the vehicle height effectively, but also achieve the on-off statuses direct control of solenoid valves.