Feedback brake distribution control for minimum pitch

The distribution of brake forces between front and rear axles of a vehicle is typically specified such that the same level of brake force coefficient is imposed at both front and rear wheels. This condition is known as ‘ideal’ distribution and it is required to deliver the maximum vehicle deceleration and minimum braking distance. For subcritical braking conditions, the deceleration demand may be delivered by different distributions between front and rear braking forces. In this research we show how to obtain the optimal distribution which minimises the pitch angle of a vehicle and hence enhances driver subjective feel during braking. A vehicle model including suspension geometry features is adopted. The problem of the minimum pitch brake distribution for a varying deceleration level demand is solved by means of a model predictive control (MPC) technique. To address the problem of the undesirable pitch rebound caused by a full-stop of the vehicle, a second controller is designed and implemented independently from the braking distribution in use. An extended Kalman filter is designed for state estimation and implemented in a high fidelity environment together with the MPC strategy. The proposed solution is compared with the reference ‘ideal’ distribution as well as another previous feed-forward solution.     

Nonlinear robust control of integrated vehicle dynamics

A new methodology to design the vehicle GCC (global chassis control) nonlinear controller is developed in this paper. Firstly, to handle the nonlinear coupling between sprung and unsprung masses, the vehicle is treated as a mechanical system of two-rigid-bodies which has 6 DOF (degree of freedom), including longitudinal, lateral, yaw, vertical, roll and pitch dynamics. The system equation is built in the yaw frame based on Lagrange's method, and it has been proved that the derived system remains the important physical properties of the general mechanical system. Then the GCC design problem is formulated as the trajectory tracking problem for a cascade system, with a Lagrange's system interconnecting with a linear system. The nonlinear robust control design problem of this cascade interconnected system is divided into two H _∞ control problems with respect to the two sub-systems. The parameter uncertainties in the system are tackled by adaptive theory, while the external uncertainties and disturbances are dealt with the H _∞ control theory. And the passivity of the mechanical system is applied to construct the solution of nonlinear H _∞ control problem. Finally, the effectiveness of the proposed controller is validated by simulation results even during the emergency manoeuvre.     

越野汽车变传动比差速器的研究

提出了一种新型变传动比锥齿轮差速器，其特点是传动比变化周期突破了单周节限制，变化幅度得以显著增大，从而增大了差速器锁紧系数，提高了汽车的越野通过能力。给出了一种非圆锥齿轮副传动的啮合分析方法，以曲面上曲线的短程曲率为桥梁和纽带，将球面节曲线伸展成平面当量节曲线，进而把复杂的球面啮合阿题简化成平面啮合问题。     

多轴汽车车身稳定性的研究

本文建立了多轴汽车纵、横向倾角及其角加速度的通用计算方法，且对相关因素的影响作了具体的分析。     

Vehicle Response to Stochastic Roadways

Dynamic response calculations for vehicles traversing irregular surfaces are usually accomplished using frequency domain methods involving spectral densities and transfer functions. Here an alternative procedure is developed which allows direct computation of mean square values and correlations of system variables for both transient and steady-state conditions. The method is based upon the differential equation for the covariance matrix which is directly related to the state equations for the vehicle. Multiple white noise inputs can be incorporated as well as inputs at two wheels which follow the same track at a distance from one another..The method is suitable for computer implementation without the complex algebra associated with finding all necessary transfer functions and the necessity of evaluating integrals in order to find mean square values using the conventional approach. As an illustration, a simple vehicle model is worked out completely and the variation of pitch and heave motion as a function of vehicle speed is plotted.     

Vehicle Response to Stochastic Roadways

SUMMARY

Dynamic response calculations for vehicles traversing irregular surfaces are usually accomplished using frequency domain methods involving spectral densities and transfer functions. Here an alternative procedure is developed which allows direct computation of mean square values and correlations of system variables for both transient and steady-state conditions. The method is based upon the differential equation for the covariance matrix which is directly related to the state equations for the vehicle. Multiple white noise inputs can be incorporated as well as inputs at two wheels which follow the same track at a distance from one another..The method is suitable for computer implementation without the complex algebra associated with finding all necessary transfer functions and the necessity of evaluating integrals in order to find mean square values using the conventional approach. As an illustration, a simple vehicle model is worked out completely and the variation of pitch and heave motion as a function of vehicle speed is plotted.     

Vision-based fusion of robust lane tracking and forward vehicle detection in a real driving environment

With the goal of developing an accurate and fast lane tracking system for the purpose of driver assistance, this paper proposes a vision-based fusion technique for lane tracking and forward vehicle detection to handle challenging conditions, i.e., lane occlusion by a forward vehicle, lane change, varying illumination, road traffic signs, and pitch motion, all of which often occur in real driving environments. First, our algorithm uses random sample consensus (RANSAC) and Kalman filtering to calculate the lane equation from the lane candidates found by template matching. Simple template matching and a combination of RANSAC and Kalman filtering makes calculating the lane equation as a hyperbola pair very quick and robust against varying illumination and discontinuities in the lane. Second, our algorithm uses a state transfer technique to maintain lane tracking continuously in spite of the lane changing situation. This reduces the computational time when dealing with the lane change because lane detection, which takes much more time than lane tracking, is not necessary with this algorithm. Third, false lane candidates from occlusions by frontal vehicles are eliminated using accurate regions of the forward vehicles from our improved forward vehicle detector. Fourth, our proposed method achieved robustness against road traffic signs and pitch motion using the adaptive region of interest and a constraint on the position of the vanishing point. Our algorithm was tested with image sequences from a real driving situation and demonstrated its robustness.     

Effects of end coils on the natural frequency of automotive engine valve springs

In this paper, we present a method for estimating the natural frequencies of various engine valve springs such as constant pitch, two-step variable pitch, three-step variable pitch, and progressive springs. Since a valve spring’s surging amplitude is magnified when the spring’s natural frequency coincides with the frequency of the cam profile harmonic components, estimating the natural frequency of the spring is the first step in predicting valve spring surging phenomena. A new method for calculating the valve spring’s natural frequency is proposed in this paper that considers the end coil effect. This method predicts not only the natural frequency of a helical spring at a fixed number of active turns, but also the change in the natural frequency as the spring is compressed. The experimental results demonstrate that nonlinear characteristics of engine valve springs can be predicted from the given initial pitch curves.     

轿车悬架空间五连杆机构尺度综合

对轿车悬架五连杆机构进行自由度计算；论述应用位置反解方程进行该机构刚体导引尺度综合的一般方法；指出轮轴构件作圆弧轨迹平动时能使车轮轨迹角不变；阐述进行该机构尺度综合的设计计算方法；由算例得到一组与实际相符的位置与结构参数值，供悬架设计时参考。     

Clarification of the mechanism of wiper blade rubber squeal noise generation

As automobiles become quieter, the noise of wiper blade rubber in motion may become a problem for passengers. To resolve this noise, especially the squeal noise, we constructed an equation of motion for the wiper blade vibration by observation and FEM stress analysis. Based on the derived equation, we discovered several important design and material items which can be utilized to reduce squeal noise.     

Investigation into untripped rollover of light vehicles in the modified fishhook and the sine maneuvers. Part I: Vehicle modelling, roll and yaw instability

Vehicle rollovers may occur under steering-only maneuvers because of roll or yaw instability. In this paper, the modified fishhook and the sine maneuvers are used to investigate a vehicle's rollover resistance capability through simulation. A 9-degrees of freedom (DOF) vehicle model is first developed for the investigation. The vehicle model includes the roll, yaw, pitch, and bounce modes and passive independent suspensions. It is verified with the existing 3-DOF roll-yaw model. A rollover critical factor (RCF) quantifying a vehicle's rollover resistance capability is then constructed based on the static stability factor (SSF) and taking into account the influence of other key dynamic factors.

Simulation results show that the vehicle with certain parameters will rollover during the fishhook maneuver because of roll instability; however, the vehicle with increased suspension stiffness, which does not rollover during the fishhook maneuver, may exceed its rollover resistance limit because of yaw instability during the sine maneuver. Typically, rollover in the sine maneuver happens after several cycles.

It has been found that the proposed RCF well quantifies the rollover resistance capability of a vehicle for the two specified maneuvers. In general, the larger the RCF, the more kinetically stable is a vehicle. A vehicle becomes unstable when its RCF is less than zero. Detailed discussion on the effects of key vehicle system parameters and drive conditions on the RCF in the fishhook and the sine maneuver is presented in Part II of this study.     

盾构推进液压系统控制模式的分析比较

盾构为隧道施工的重大技术装备,推进系统性能的好坏直接影响盾构姿态、施工开挖隧道线路的精准度以及掘进速度。盾构在软弱地层的施工过程中,某些盾构容易出现姿态控制困难及"栽头"现象,文章通过对不同厂家推进系统控制模式进行研究及原因分析,从理论上与实际监测进行比较得出结论。就目前国内外盾构产品而言,推进液压系统控制模式主要有2种,比例压力流量复合控制方案和比例减压阀控制方案,通过AMESim仿真、理论分析,并结合现场的实际监测数据比较了2种控制模式下执行机构动态响应特性,从而对盾构的可操作性及姿态控制特性进行分析比较,以期对推进液压系统的设计及盾构的选型、使用有一定的参考价值。     

某车型行李舱门开启弹力过大的解决措施

为解决某车型行李舱门开启时弹力过大问题,探究改变行李舱门开启时弹力的方法,文章以鹅颈式铰链加扭杆弹簧的布置形式为研究对象,对行李舱门在各个开启状态时的受力情况加以分析。通过将行李舱门铰链摆臂安装孔位置上移（与原孔孔心距10mm）和将扭杆弹簧固定端与活动端之间的初始角度由35°减小为30°,使行李舱门满足各个开启状态时的最佳受力情况,为今后的扭杆弹簧以及行李舱门铰链的设计提供了参考。     

贵阳小黄河河道整治及截污工程设计

阐述了贵阳市小河区内主要河流之一———小黄河河道的防洪、截污管、景观、水面组织等综合整治工程的设计概况以及存在的主要问题。工程建成后,使小河区环境卫生条件有很大改观,同时也提高了居民的生活质量。     

Investigation of a passenger car's dynamic response due to a flywheel-based kinetic energy recovery system

With the advent of flywheel-based kinetic energy recovery systems in automotive applications new safety issues arise as a consequence of the flywheel's high rotational speed. While the special structural safety requirements of the components are well discussed in the literature, there is still little research on the influence of gyroscopic effects on vehicle dynamics. The aim of this paper is to investigate the influence of a typical high-speed flywheel on the driving dynamics of an average passenger car. To this end the equations of motion of a gyroscope are derived, which relate the vehicle's roll, pitch and yaw rate with the transverse torque acting on the flywheel. These equations are implemented in a commercial vehicle dynamics simulation program in order to determine the reaction torques acting on the vehicle within a representative range of driving situations. Numerical simulations indicate that the gyroscopic effect can be considered insignificant in standard driving situations.     

Estimation of valve spring surge amplitude using the variable natural frequency and the damping ratio

Internal vibration of the valve spring is a critical factor in determining the dynamic characteristics of high-speed valve train systems. Because precise prediction of the spring surge amplitude is a difficult problem, especially for nonlinear variable-pitch springs, the development stage requires a process of trial and error. In the present study, a new method that considers the variable natural frequency and variable damping ratio is proposed to predict the spring surge amplitude. First, the change in the natural frequency and damping ratio caused by compression is predicted from the initially given pitch curve at the free height. Second, the spring surge amplitude is estimated by solving the wave equation with nonlinear variable coefficients. The surge amplitudes of typical valve springs are also measured using a motoring test rig and are compared with theoretical results predicted by the spring drawing and cam profile data.     

哈尔滨市防洪基本情况和防灾减灾的对策措施

该文综述哈尔滨市城市防洪工程总体情况、汛情和洪涝灾害分析、城市防洪存在的主要问题以及防洪减灾的对策措施。     

Estimation of land vehicle roll and pitch angles

In this article, two kinematics-based observers are proposed to estimate the vehicle roll and pitch angles by using an inertial measurement unit. The observers are mathematically proven to be stable if the vehicle yaw rate is not zero. With a design variation of the observer gains, the estimated roll or pitch angle is shown to further asymptotically converge to the true value, eliminating possible errors caused by the biases of the acceleration signals. Simulation results show that accurate estimation of both pitch and roll angles can be achieved without the help of external sensors such as global positioning systems, either by using the accelerometer-based reference pitch or roll angle as the maneuver varies, or by using an observer with zero steady-state error property.     

湿热地区沥青混合料配合比设计研究

针对我国南方湿热多雨的气候条件,通过采用贝雷法对连续密级配沥青混合料进行矿料级配设计和检验,提出了与之相应的贝雷法检验指标适用范围。研究表明,采用贝雷法对连续密级配沥青混合料进行设计,可使矿料级配达到骨架密实结构的效果,具有良好的抗永久变形能力和抗水损害能力,并较好地改善了沥青路面施工中的级配离析问题和压实度不足问题,满足了湿热地区对沥青路面的性能要求。