Performance analysis of air suspension system of heavy truck with semi-active fuzzy control

In order to analyze and evaluate the performance of the air suspension system of heavy trucks with semi-active fuzzy control, a three-dimensional nonlinear dynamical model of a typical heavy truck with 16-DOF（degree of freedom） is established based on Matlab/Simulink software. The weighted root-mean-square（RMS） acceleration responses of the vertical driver ＇s seat, the pitch and roll angle of the cab, and the dynamic load coefficient（DLC） are chosen as objective functions, and the air suspension system is optimized and analyzed by the semi-active fuzzy control algorithm when vehicles operate under different operation conditions. The results show that the influence of the roll angle of the cab on the heavy truck ride comfort is clear when vehicles move on the road surface conditions of the ISO level D and ISO level E at a velocity over 27.5 m/s. The weighted RMS acceleration responses of vertical driver＇ s seat, the pitch and roll angle of the cab are decreased by 24%, 30% and 25%, respectively,when vehicles move on the road surface condition of the ISO level B at a velocity of 20 m/s. The value of the DLC also significantly decreases when vehicles operate under different operation conditions. Particularly, the DLC value of the tractor driver axle is greatly reduced by 27.4% when the vehicle operates under a vehicle fully-loaded condition on the road surface condition of ISO level B at a velocity of 27.5 m/s.

Nonlinear dynamic analysis of interaction between vehicle and road surfaces for 5-axle heavy truck

Based on the analysis of nonlinear geometric characteristics of the suspension systems and tires, a 3D nonlinear dynamic model of a typical heavy truck is established. The impact factors of dynamic tire loads, including the dynamic load stress factors, and the maximal and the minimal vertical dynamic load factors, are used to evaluate the dynamic interaction between heavy vehicles and roads under the condition of random road surface roughness. Matlab/Simulink is used to simulate the nonlinear dynamic system and calculate the impact factors. The effects of different road surface conditions on the safety of vehicle movement and the durability of parts of a vehicle are analyzed, as well as the effects of different structural parameters and different vehicle speeds on road surfaces. The study results provide both the warning limits of road surface roughness and the limits of corresponding dynamic parameters for the 5-axle heavy truck.

Comparison of two suspension control strategies for multi-axle heavy truck

Two simple and effective control strategies for a multi-axle heavy truck, modified skyhook damping (MSD) control and proportional-integration-derivative (PID) control, were implemented into functional virtual prototype (FVP) model and compared in terms of road friendliness and ride comfort. A four-axle heavy truck-road coupling system model was established using FVP technology and validated through a ride comfort test. Then appropriate passive air suspensions were chosen to replace the rear tandem suspensions of the original truck model for preliminary optimization. The mechanical properties and time lag of dampers were taken into account in simulations of MSD and PID semi-active dampers implemented using MATLAB/Simulink. Through co-simulations with Adams and MATLAB, the effects of semi-active MSD and PID control were analyzed and compared, and control parameters which afforded the best comprehensive performance for each control strategy were chosen. Simulation results indicate that compared with the passive air suspension truck, semi-active MSD control improves both ride comfort and road-friendliness markedly, with optimization ratios of RMS vertical acceleration and RMS tyre force ranging from 10.1% to 44.8%. However, semi-active PID control only reduces vertical vibration of the driver's seat by 11.1%, 11.1% and 10.9% on A, B and C level roads respectively. Both strategies are robust to the variation of road level.

Rollover Prevention and Motion Planning for an Intelligent Heavy Truck

It is very necessary for an intelligent heavy truck to have the ability to prevent rollover independently.However,it was rarely considered in intelligent vehicle motion planning.To improve rollover stability,a motion planning strategy with autonomous anti rollover ability for an intelligent heavy truck is put forward in this paper.Considering the influence of unsprung mass in the front axle and the rear axle and the body roll stiffness on vehicle rollover stability,a rollover dynamics model is built for the intelligent heavy truck.From the model,a novel rollover index is derived to evaluate vehicle rollover risk accurately,and a model predictive control algorithm is applicated to design the motion planning strategy for the intelligent heavy truck,which integrates the vehicle rollover stability,the artificial potential field for the obstacle avoidance,the path tracking and vehicle dynamics constrains.Then,the optimal path is obtained to meet the requirements that the intelligent heavy truck can avoid obstacles and drive stably without rollover.In addition,three typical scenarios are designed to numerically simulate the dynamic performance of the intelligent heavy truck.The results show that the proposed motion planning strategy can avoid collisions and improve vehicle rollover stability effectively even under the worst driving scenarios.

Active Noise Control of the Heavy Truck Interior Cab

In order to control the noise of the heavy truck interior cab effectively, the active noise control methods are employed. First, an interior noise field test for the heavy truck is performed, and frequencies of interior noise of this vehicle are analyzed. According to the spectrum analysis of acquired noise signal, it is found out that the main frequencies of interior noise are less than 800Hz. Then the least squares lattice （LSL） algorithm is used as signal processing algorithm of the controller and a closed-loop control DSP system, based on TMS 320VC5416, is developed. The residual signal at driver＇s ear is used as feedback signal. Lastly, the developed ANC system is loaded into the heavy truck cab, and controlling the noise at driver＇ s ear for that truck at different driving speeds is attempted. The noise control test results indicate that the cab interior noise is reduced averagely by 0.9 dBA at different driving speeds.

Numerical simulation of dynamic response of subgrade under moving heavy truck in cold regions

This paper reports on the dynamic response of highway subgmde under moving heavy Wuck in cold regions. Numerical simulations are performed in two stages. In the first stage, the moving heavy truck vibration, induced by mad roughness, is calculated through a three-dimensional dynamic interaction model of heavy tmckavement-subgrade, and the lime-histories of nodal loads on the top of the base are calculated through this model. In the second stage, a two-dimensional dynamic finite element model of the bgrade-ground system is formulated, using the calculated nodal loads from the first stage as input. The dynamic resporkse of the subgrade is validated by field measurements, and the effects of mack type, axle loading, running speed, and road roughness on the vertical dynamic slress in the unfrozen period and the spring thawing period are analyzed and discussed.

基于Trucksim的整车动力性能仿真分析

利用Trucksim软件对某重型商用车进行建模及动力性能仿真,将仿真结果与理论计算值进行比较和分析。结果表明,采用Trucksim建模仿真得到的动力性指标结果均比理论计算结果更加准确。

Probabilistic Lane-Change Decision-Making and Planning for Autonomous Heavy Vehicles

To improve the safety and driving stability of the autonomous heavy truck, it is necessary to consider the differences of driving behavior and drivable trajectories between the heavy trucks and passenger cars. This study proposes a probabilistic decision-making and trajectory planning framework for the autonomous heavy trucks. Firstly, the driving decision process is divided into intention generation and feasibility evaluations, which are realized using the utility theory and risk assessment, respectively. Subsequently the driving decision is made and sent to the trajectory planning module. In order to reflect the greater risks of the truck to other surrounding vehicles, the aggressiveness index(AI) is proposed and quantified to infer the asymmetrical risk level of lane-change maneuver. In the planning stage, the lateral and roll dynamics stability domains are developed as the constraints to exclude the candidate trajectories that would cause vehicle instability. Finally, the simulation results are compared between the proposed model and the artificial potential filed model in the scenarios extracted from the naturalistic driving data. It is shown that the proposed framework can provide the human-like lane-change decisions and truck-friendly trajectories, and performs well in dynamic driving environments.

重卡发展技术路线及电气化进程探讨

近年来,中国重卡产销量进入震荡下行和深度调整阶段,动力构成优化速度加快。在“双碳”目标和汽车电动化两大国家战略背景下,中国重卡正在经历从燃油车向电动、氢重卡的逐渐转型。各技术路线的经济性直接影响其发展速度和发展规模,不同技术路线的重卡在实际使用过程中各有优势,政策层面对各技术路线的发展导向和支持力度也明显不同。未来中国重卡动力构成优化速度将明显加快,预计短期内LNG重卡依然是替代柴油重卡的主力,电动重卡销量将明显提升,氢燃料电池重卡继续保持小规模增长,并有望于“十五五”期间取得明显的技术突破。建议沿着油-气(LNG为主)-电-氢的道路稳步推进重卡的电气化进程。

集装箱港口集疏运重卡电动化的经济性分析

为分析集装箱港口集疏运重卡电动化的经济性,考虑购置税优惠、补贴、贷款、排放成本等因素,建立广义总拥有成本现值估算模型,构建经济性分析指标,并分析“购买底盘+电池”(方案1)和“购买底盘+租赁电池”(方案2)的经济性。结果表明,在设定条件下,无论是否考虑排放成本,两种方案都不具经济性,但考虑排放成本能有效缓解重卡电动化的成本劣势。当考虑排放成本且其他因素不变时,若电池租金<5.61万元,或电价≤1.28元/(kW·h),或油价≥8.48元/L,或柴油重卡能耗强度≥0.40 L/km,或电动重卡能耗强度≤1.34 (kW·h)/km,方案2具有经济性。类似地,若使方案1具有经济性,应满足电池价格<22.11万元,或电价<1.23元/(kW·h),或油价>8.72元/L,或柴油重卡能耗强度≥0.41 L/km,或电动重卡能耗强度≤1.28 (kW·h)/km。免征电动重卡购置税能有效改善两种方案的经济性指标。调增单位排放成本或电动重卡补贴额度虽能确保两种方案都具有经济性,但其所需调增幅度较高,可能增加重卡司机或政府的经济负担。

重卡传动轴用高强7075铝合金热流变行为及径向锻造微观组织演变

为研究重型卡车轻量化传动轴用高强7075铝合金在径向锻造时的热变形行为,将大直径7075铝合金挤压棒料预热退火后,取样进行了不同变形条件下的等温压缩试验。分别考虑温度与应变速率对应变强化及软化的影响,构建了适用于中大型7075铝合金传动轴热加工的改进Hansel-Spittel本构模型。根据动态材料模型理论获得了7075铝合金的热加工图,并据此分析了7075铝合金棒料在典型径向锻造工艺中的组织变化。研究结果表明:改进Hansel-Spittel模型能更准确地模拟预热退火态7075铝合金的峰值和稳态流变应力,预测值与试验值的平均相对误差仅为2.71%;7075铝合金在温度为350~450℃、应变速率为0.01~10 s^(-1)范围内具有较高的热加工稳定性,高温及低应变速率的变形条件有利于材料的微观组织演化;预热退火态7075铝合金棒料在经过截面收缩率为55.6%的径向锻造工艺和T6热处理后,原始板条晶粒转变为细化大转角晶粒组织,抗拉强度提高至651 MPa,延伸率提高至12.5%,综合性能得到显著改善。

重型载货汽车长下坡制动控制策略

单一制动器温度升高出现制动热衰退现象后,其余制动器热负荷增加会影响整车制动效能,针对此问题提出了基于制动力观测模型的重型载货汽车长大下坡制动控制策略。首先,利用制动鼓温度能够准确表征制动力的特性建立了制动力观测模型;其次,依据整车制动器热衰退演变机理及车辆制动失稳机理,提出了结合散热量、地面附着率、滑移率及轴载的控制策略;然后,为了实现制动力的跟踪控制,建立了基于MPC制动力优化控制模型;为了验证提出的控制策略,建立了基于TruckSim和Matlab联合仿真模型;最后,进行低温制动工况、高温制动工况和基于滑移率的制动控制策略仿真验证。结果表明:低温工况能够抑制制动器温度的快速升高;高温工况能够降低制动器提前出现热衰退的风险,在保证整车制动效能的同时,预留了必要安全措施时间;基于滑移率的控制策略可以保证车辆制动稳定性。结果表明:所提出的控制策略既能相对均衡地控制制动器温度上升速度,又能避免因某一制动器温度快速升高而增加其余制动器热负荷,且保证制动稳定性,从而提高了重型载货汽车长下坡制动安全性。

基于行驶特征区间划分的重型载货汽车实际道路能耗评价方法

提出一种基于行驶特征区间划分的能耗评价方法。通过对中国货车行驶工况的工况点分布特征进行分析,确定了速度和加速度区间的数量与边界的划分方案。考虑道路坡度的影响,进行实际道路试验数据筛选,并用于计算不同行驶特征区间内的燃油消耗量平均值。结合中国货车行驶工况在不同行驶特征区间内的累计行驶里程,计算能耗评价结果。为了验证该方法的有效性,开展了3次底盘测功机试验和2次实际道路行驶试验,结果表明,所提出的能耗评价方法能提高重型载货汽车实际道路能耗评价结果的复现性。

矿用重载轮胎趾口空问题的研究

通过市场返回轮胎断面剖析,结合有限元仿真分析造成矿用重载轮胎趾口空的原因,并提出相应的解决措施。通过采取适当减小胎圈内直径,适当增大胎圈与轮辋过盈量、三角胶尺寸、胎体反包高度,提高耐磨胶的硬度和耐老化性能,在推荐充气压力和负荷范围内使用轮胎及在车辆上安装液压减速器以降低刹车片使用频次等措施,可降低趾口空发生率,延长轮胎使用寿命。

矿用重载轮胎接地印痕的研究

以14.00R25宽体自卸车轮胎为例,通过轮胎使用情况调研,结合实验室测试和轮胎有限元仿真,研究矿用重载轮胎接地印痕及接地压力分布。结果表明:宽体自卸车轮胎接地印痕形状应接近矩形且接地压力分布均匀;影响轮胎接地印痕及接地压力分布的主要因素为断面高宽比、胎冠弧半径和弧度高、带束层角度和宽度、花纹沟壁角度和花纹沟宽度等。通过有限元仿真优化设计可避免轮胎出现花纹掉块和非均匀磨损等问题,提高设计效率。

超重型消防车地下室顶板荷载等效取值研究

目前国内各大城市均有采购多辆101 m登高平台消防车(63 t),其重量远远超过了《建筑结构荷载规范》(GB 50009—2012)中原型消防车的重量(30 t),《建筑结构荷载规范》(GB 50009—2012)未对此类消防车给出具体的等效均布荷载取值。以101 m登高平台消防车(63 t)为研究对象,首先通过绘制板的跨中弯矩影响面来确定其最不利位置,然后利用ABAQUS计算出2种荷载工况下板的跨中弯矩值,最后再等效出101 m登高平台消防车(63 t)分别在7 m×7 m、8 m×8 m、9 m×9 m双向板的荷载取值。结果表明:板跨大于6 m的地下室双向板消防车荷载不建议直接取规范值,可按照设计需要采用相应流程进行等效;若对地下室顶板设计精度要求不高,当双向板板跨大于8 m时,63 t级消防车可参照规范要求进行荷载等效。

货运交通电气化技术的电气化公路方案与氢能方案对比研究

重型货车是我国交通运输行业的高耗能设备和主要的碳排放来源,其柴油年消耗量约占我国柴油年消耗总量的40%、CO_(2)年排放量占交通运输领域CO_(2)年排放总量的50%左右。在“双碳”目标和能源革命的背景下,构建绿色清洁、安全高效的公路货运方式,推进重载货运交通的低碳化和清洁化转型,这已成为一种必然趋势。目前,重型货车电气化主要有充电方案、换电方案、氢能重卡方案以及电气化公路方案。文章主要介绍了氢能重卡方案和电气化公路方案,并基于某运煤专线,通过成本核算,对比分析了二者的经济性和应用场景。分析结果表明,对于固定运输线路的货运交通,当年运量大于204.83万吨时,采用电气化公路方案更具有经济性;当年运量低于204.83万吨时,氢能重卡方案成本则更低。

参与电网削峰调节的电动重卡换电站调度策略

换电站因其快速、便捷的特点获得了迅猛的推广和发展。在电动重卡领域,换电站建设已初具规模并保持高速发展。如何对电动重卡换电站进行充电调度以实现电网友好,是一个重点研究方向。首先,针对电动重卡换电需求在时间上分布规律较弱的特点,使用统计分析法分析换电站历史运行数据,得到一天内各时段的换电需求预测值;其次,提出基于换电需求预测的日内调度策略和基于实际换电需求的日内实时修正策略,以确定电池充电数量和允许充电时间;然后,建立以电网削峰为目标的时间-功率模型,结合电网背景负荷曲线,使用差分算法对电池的充电功率和实际充电时间进行求解;最后,通过算例证明了调度策略和时间-功率模型的有效性。

基于模型标定的重型卡车座椅动态舒适性仿真研究

为了减轻重型卡车驾驶员的疲劳,增加了减振机构来提高座椅的动态舒适性。提出一种基于模型标定的座椅动态舒适性研究方法。首先通过台架试验得到了空气弹簧的刚度和阻尼器的阻尼参数。然后对座椅进行模态试验和传递率特性试验,获得座椅模态频率与传递率信息,采用迭代寻参的方法确定连接部位的刚度和阻尼参数,从而建立准确的有限元模型。最后进行模态、传递率和随机振动仿真分析,通过仿真结果评估座椅动态舒适性。结果表明,仿真与试验的模态频率误差小于3%,传递率峰值误差小于10%,且该座椅固有频率与人体敏感频率不重合,座椅在非共振频率段的传递率较小。降低共振频率下传递率的波峰值与响应点的均方根加速度值可以提高座椅的动态舒适性。

燃料电池重卡动力系统参数匹配与能量管理策略仿真分析

为提高燃料电池重卡综合性能,首先确定了其动力系统构型方案,依据整车动力性与经济性要求对驱动电机、燃料电池以及动力电池进行部件选型和参数匹配,利用AVL Cruise软件搭建了整车物理模型。制定了一种基于模糊控制方法的能量管理策略,并在MATLAB/Simulink环境下建立模糊控制能量管理策略模型。通过MATLAB DLL方式实现了能量管理策略模型与整车物理模型的联合仿真。仿真结果表明所提出的整车动力系统设计方案和能量管理策略能够满足整车动力性并有效地提高了整车的燃料经济性。