The Steering Characteristics of Multiple Axle Bogie Systems

SUMMARY

Legislation limits the load that may be transferred to the roadway by the axies of a commercial vehicle and this has resulted in the development of multi axle bogies for both the tractor and trailer units of articulated vehicles and at the rear of rigid vehicles, some of these bogies contain self steering or articulation steered axles

Experience shows that the tyre wear characteristics of multi axle bogies may be unsatisfactory. The paper analyses the role of such bogies in the context of vehicle handling and shows how the lateral tyre forces vary between the axles. An hypotheses relating the forces in a steady state turn to wear is given. The analysis may also be applied to the general case of vehicle handling.     

Dynamic Behaviour of Ore Wagons in Curves at Malmbanan

The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increase in axle load is thereby wanted. The fleet of ore wagons of today at Malmbanan/Ofotbanan in northern Sweden and Norway has to be updated. It is of interest to find out if it is possible to allow a higher axle load on the track with new wagons

To be able to understand and predict the effects on track wear depending on what type of vehicle that is in use, the contact forces between wheels and rails have to be determined. A computer aided analysis has been made of the dynamic behaviour of three test vehicles equipped with different types of three-piece bogies running at Malmbanan. The vehicles are modelled and their interaction with the track is analysed using the multibody simulation package GENSYS

The simulations show that, even if the axle load is increased from 25 tons to 30 tons and the velocity is increased from 50 km/h to 60 km/h, it is possible to reduce lateral track forces and wear in curves by using a different bogie than the standard three-piece bogie used today.     

Dynamic Behaviour of Ore Wagons in Curves at Malmbanan

SUMMARY

The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increase in axle load is thereby wanted. The fleet of ore wagons of today at Malmbanan/Ofotbanan in northern Sweden and Norway has to be updated. It is of interest to find out if it is possible to allow a higher axle load on the track with new wagons

To be able to understand and predict the effects on track wear depending on what type of vehicle that is in use, the contact forces between wheels and rails have to be determined. A computer aided analysis has been made of the dynamic behaviour of three test vehicles equipped with different types of three-piece bogies running at Malmbanan. The vehicles are modelled and their interaction with the track is analysed using the multibody simulation package GENSYS

The simulations show that, even if the axle load is increased from 25 tons to 30 tons and the velocity is increased from 50 km/h to 60 km/h, it is possible to reduce lateral track forces and wear in curves by using a different bogie than the standard three-piece bogie used today.     

Vehicle-Generated Road Damage: A Review

The literature concerned with road damage caused by heavy commercial vehicles is reviewed. The main types of vehicle-generated road damage are described and the methods that can be used to analyse them are presented. Attention is given to the principal features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Also discussed are those vehicle features which, to a first approximation, can be studied without consideration of the dynamics of the vehicle, including axle and tyre configurations, tyre contact conditions and static load sharing in axle group suspensions. The main emphasis of the paper is on the dynamic tyre forces generated by heavy vehicles: their principal characteristics, their simulation and measurement, the effects of suspension design on the forces and the methods that can be used to estimate their influence on road damage. Some critical research needs are identified.     

Efficiency analysis of a multiple axle vehicle with hydrostatic transmission overcoming obstacles

Transmission configurations in off-road vehicles with multiple driven axles can be a determining factor in the obstacle surmounting capacity and also in the vehicle efficiency. An off-road articulated vehicle with four driven axles, four bogies and two modules has been considered for the global hydrostatic transmission efficiency analysis and for the vehicle functional efficiency analysis. The power flow through the transmission system has been quantified from the combustion engine shaft to each axle of the wheels. It has been done for different the operating conditions and taking into account the wheel–terrain interaction and the transmission configuration, that could lead to a forced slippage of some of the wheels. Results show the influence of the different wheels’ requirements, the transmission configuration limitations and the considered control strategy on the global transmission and vehicle functional efficiencies.     

商用车双转向桥中间杆系优化设计

商用车双转向桥包含两个独立的转向梯形机构,它们之间的运动是通过中间杆系来传递的.在设计双转向桥转向系统时,为了避免转向桥轮胎异常磨损,需要两个转向桥的车轮转角协调变化.提出了一种对现有双转向桥中间杆系优化设计的方法,可协调车辆第一、第二转向桥的转角关系,避免了横向滑移导致的双前桥车轮转向时造成的轮胎异常磨损.     

Rail Vehicles' Riding Quality and Comfort Related to Theoretical and Experimental Optimization Application to High Speed Trains

SUMMARY

The literature concerned with road damage caused by heavy commercial vehicles is reviewed. The main types of vehicle-generated road damage are described and the methods that can be used to analyse them are presented. Attention is given to the principal features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Also discussed are those vehicle features which, to a first approximation, can be studied without consideration of the dynamics of the vehicle, including axle and tyre configurations, tyre contact conditions and static load sharing in axle group suspensions. The main emphasis of the paper is on the dynamic tyre forces generated by heavy vehicles: their principal characteristics, their simulation and measurement, the effects of suspension design on the forces and the methods that can be used to estimate their influence on road damage. Some critical research needs are identified.     

Influence of the transmission configuration of a multiple axle vehicle on the obstacle surmounting capacity

Conventional wheeled vehicles have serious mobility limitations in rough terrain while walking vehicles have inherent drawbacks such as a high number of DOF and actuators, control complexity and low-energy efficiency. Vehicles that passively adapt the position of multiple wheels to maintain contact with the ground can be a good compromise between both conventional wheeled and walking vehicles. One way to increase the number of wheels in contact with the ground is using bogies. However, the kinematics of a multiple axle vehicle moving on irregular terrain is quite complex since every wheel can require different angular speed to avoid slippage. The present work aims to quantify the obstacle surmounting capacity of a four axle, double-bogie vehicle depending on the transmission configuration, since it can provoke the slippage of some of its wheels.

Some results are presented corresponding to the vehicle moving on a straight upward slope of different angles and facing variable obstacles in any of its axles.

It can be observed that as more restricted the transmission is, more wheels are forced to slip and less traction the vehicle has, and, as a consequence, less obstacle surmounting capacity.     

Front-Rear Interaction of a Pitch-Plane Truck Model

Results from a previously reported experimental study on heavy articulated vehicles show that the choice of tractor unit strongly affects the dynamic tyre forces generated by the trailer axles, but the choice of trailer unit does not strongly affect the tyre forces generated by the tractor axles. These results have implications for assessing the road-friendliness of tractor and trailer units. The objectives of the work described in this paper are to understand the dynamic interaction between the tractor and trailer unit, and to identify the conditions for which strong interaction exists. A mathematical model with two degrees of freedom is used to simulate the pitch-plane dynamics of an articulated vehicle. Three idealized vehicles are investigated and three conditions for strong dynamic interaction are identified. It is thought that these conditions are likely to exist in a large proportion of heavy trucks.     

Vehicle dynamics control of an electric-all-wheel-drive hybrid electric vehicle using tyre force optimisation and allocation

ABSTRACT

Hybrid Electric Vehicles (HEV) offer improved fuel efficiency compared to conventional vehicles at the expense of adding complexity and at times, reduced total power. As a result, HEV generally lack the dynamic performance that customers enjoy. To address this issue, the paper presents a HEV with electric All-Wheel-Drive capabilities via the use of torque vectoring electric rear axle drive (TVeRAD) to power the rear axle. The addition of TVeRAD to a front wheel drive HEV improves the total power output. To improve the handling characteristics of the vehicle, the TVeRAD provides torque vectoring at the rear axle. A bond graph model of the drivetrain is developed and used in co-simulation with CarSim. The paper proposes a control system which utilises control allocation to optimise tyre forces. The proposed control system is tested in the simulation environment with a high fidelity CarSim vehicle model. Simulation results show the control system is able to maximise vehicle longitudinal performance while avoiding tyre saturation on low mu surfaces. More importantly, the control system is able to track the desired yaw moment request on a high speed double lane change manoeuvre through the use of the TVeRAD to improve the handling characteristic of the vehicle.     

Independent Suspension, Self Steered Axle, and 4WS for Busses

The dynamic behavior of commercial vehicles fitted with differentr types of suspension mechanisms and steering devices is investigated in this paper. Six vehicle models have been constructed: 2WS-SA is a standard two wheel steering bus with solid axles; 2WS-DW is a 2WSA vehicle with independent double wishbone suspension in front and rear axles; SSA-SA is a 2WS system with solid axles, the rear one being mounted on a self steered mechanism; SSA-DW is a vehicle with independent double wishbone suspension in the front axle, and a solid self steered rear axle; 4WS-SA has four wheel steering with solid axles; and 4WS-DW is a 4WS vehicle with independent double wishbone suspension in front and rear axles. The dynamic response of these models has been assessed in terms of lateral acceleration, yaw velocity, tire forces, tire force reserves, and slip angles. The expected advantages of a 4WS system (higher acceleration rates and lower slip angles) will be corroborated but, at the same time, it will be shown that they are obtained at the cost of lower force reserves. Self steered mechanisms produce smaller body slip angles, but it will be shown that they give rise to larger yaw velocity overshootings. The particular independent suspension analyzed does not show significant improvements with respect to the solid axle counterpart.     

Integrated chassis control for a three-axle electric bus with distributed driving motors and active rear steering system

This paper describes an integrated chassis control framework for a novel three-axle electric bus with active rear steering (ARS) axle and four motors at the middle and rear wheels. The proposed integrated framework consists of four parts: (1) an active speed limiting controller is designed for anti-body slip control and rollover prevention; (2) an ARS controller is designed for coordinating the tyre wear between the driving wheels; (3) an inter-axle torque distribution controller is designed for optimal torque distribution between the axles, considering anti-wheel slip and battery power limitations and (4) a data acquisition and estimation module for collecting the measured and estimated vehicle states. To verify the performances, a simulation platform is established in Trucksim software combined with Simulink. Three test cases are particularly designed to show the performances. The proposed algorithm is compared with a simple even control algorithm. The test results show satisfactory lateral stability and rollover prevention performances under severe steering conditions. The desired tyre wear coordinating performance is also realised, and the wheel slip ratios are restricted within stable region during intensive driving and emergency braking with complicated road conditions.     

交通视频辅助的桥梁动态称重方法研究

为了进一步提升既有的桥梁动态称重技术，提出一种交通视频辅助的新型桥梁动态称重方法。首先介绍基于深度神经网络的计算机视觉目标检测技术和一种计算机视觉坐标转换方法，实现从交通监控视频中实时地探测与定位桥上行驶的车辆和车轴。然后引入桥梁应变分解方法和应变影响面识别方法，建立车重、车辆位置与桥梁应变之间的映射关系，从而建立一种综合利用时间和空间冗余信息对车辆进行称重的方法。该方法构建超定的影响面加载方程组，使用最小二乘法求解该方程组以得到桥上行驶车辆的轴重和总重。最后总结出一套交通视频辅助的桥梁动态称重方法框架。为验证以上方法，在某连续大箱梁桥的缩尺模型以及实桥上进行试验。试验包含单车、双车、跟车、并行、直行、变道、匀速、变速等复杂交通工况。模型试验结果表明：该方法的车辆总重识别误差均值为-2.02%，标准差为4.77%；车辆轴重的识别误差均值为4.77%，标准差为17.50%。实桥试验结果表明：该方法的车辆总重识别误差均值为0.21%，标准差为1.53%；车辆轴重的识别误差均值为-3.59%，标准差为42.67%。除此以外，所提出的方法还可用于识别桥上车辆的数量、类型、轴数、实时位置、运动轨迹、行驶速度等多粒度交通信息。     

State estimation in roll dynamics for commercial vehicles

Accurate lateral load transfer estimation plays an important role in improving the performance of the active rollover prevention system equipped in commercial vehicles. This estimation depends on the accurate prediction of roll angles for both the sprung and the unsprung subsystems. This paper proposes a novel computational method for roll-angle estimation in commercial vehicles employing sensors which are already used in a vehicle dynamic control system without additional expensive measurement units. The estimation strategy integrates two blocks. The first block contains a sliding-mode observer which is responsible for calculating the lateral tyre forces, while in the second block, the Kalman filter estimates the roll angles of the sprung mass and those of axles in the truck. The validation is conducted through MATLAB/TruckSim co-simulation. Based on the comparison between the estimated results and the simulation results from TruckSim, it can be concluded that the proposed estimation method has a promising tracking performance with low computational cost and high convergence speed. This approach enables a low-cost solution for the rollover prevention in commercial vehicles.     

Influence of polygonal wear of railway wheels on the wheel set axle stress

The coupled vehicle/track dynamic model with the flexible wheel set was developed to investigate the effects of polygonal wear on the dynamic stresses of the wheel set axle. In the model, the railway vehicle was modelled by the rigid multibody dynamics. The wheel set was established by the finite element method to analyse the high-frequency oscillation and dynamic stress of wheel set axle induced by the polygonal wear based on the modal stress recovery method. The slab track model was taken into account in which the rail was described by the Timoshenko beam and the three-dimensional solid finite element was employed to establish the concrete slab. Furthermore, the modal superposition method was adopted to calculate the dynamic response of the track. The wheel/rail normal forces and the tangent forces were, respectively, determined by the Hertz nonlinear contact theory and the Shen–Hedrick–Elkins model. Using the coupled vehicle/track dynamic model, the dynamic stresses of wheel set axle with consideration of the ideal polygonal wear and measured polygonal wear were investigated. The results show that the amplitude of wheel/rail normal forces and the dynamic stress of wheel set axle increase as the vehicle speeds rise. Moreover, the impact loads induced by the polygonal wear could excite the resonance of wheel set axle. In the resonance region, the amplitude of the dynamic stress for the wheel set axle would increase considerably comparing with the normal conditions.     

基于Hyperworks的微型车车桥疲劳寿命分析与研究

驱动桥是汽车上主要部件之一,驱动桥的质量好坏会大大影响到车辆的安全使用。在车辆不断向高速、轻量、低能耗和高性能发展的今天,微型车车桥的安全性日益受到关注。本文以实体单元为基础,通过Proe软件对微型汽车车桥进行建模,利用Hyperworks对模型进行有限元模拟分析。在随机载荷下的对其疲劳寿命予以分析,并对驱动桥的疲劳强度进行了计算,得出了驱动桥的应力和变形分布。通过强度评价和疲劳寿命估算,验证了该车桥设计的合理性,为商用车车桥设计研发提供了参考。     

多轴移动荷载下沥青路面的动态响应特性

为分析多轴移动荷载下沥青路面的动态响应特性,通过现场调查建立了不同轴型作用下沥青路面的三维有限元模型,分别研究了单后轴、双后轴及三后轴轴载均匀分布、三后轴车轴载不均匀分布及三后轴车前轴悬空条件下对路面的影响。结果表明:多轴车轴距大于3 m时,各轴对路面的作用相互独立,轴数的增加对路面竖向位移产生叠加作用,对路表最大剪应力及压应力影响不明显;三后轴车中轴对路面竖向位移作用最大,较前轴及后轴分别增大23.7%和18.2%,中轴及后轴对路表剪应力有一定影响,而各轴对路表最大压应力基本没有影响。研究结果显示多轴车轴载不均匀分布对路面破坏会产生较大影响。     

A combined-slip predictive control of vehicle stability with experimental verification

In this paper, a model predictive vehicle stability controller is designed based on a combined-slip LuGre tyre model. Variations in the lateral tyre forces due to changes in tyre slip ratios are considered in the prediction model of the controller. It is observed that the proposed combined-slip controller takes advantage of the more accurate tyre model and can adjust tyre slip ratios based on lateral forces of the front axle. This results in an interesting closed-loop response that challenges the notion of braking only the wheels on one side of the vehicle in differential braking. The performance of the proposed controller is evaluated in software simulations and is compared to a similar pure-slip controller. Furthermore, experimental tests are conducted on a rear-wheel drive electric Chevrolet Equinox equipped with differential brakes to evaluate the closed-loop response of the model predictive control controller.     

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.