Effect of the off-road terrains on the ride comfort of construction vehicles

In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.

Technology Development of Unmanned Underwater Vehicles (UUVs)

In recent years, the weapon systems have been changing drastically because of the advancement of science technology and the change of military concept of combat. There is an unmanned system at the center of all those changes. Especially, in case of maritime environment, as the center stage of combat has changed from ocean to coastal areas, it is difficult for the existing naval forces to effectively operate in shallow waters. Therefore, unmanned underwater vehicles (UUVs) are being required at an increasing pace. In this paper, we analyze the characteristics of already developed UUVs, which are the key unmanned system of the marine battlefield environment in the future. Through the analysis of development cases and the investigation of the essential technologies, the critical design issues of UUVs are elaborated. We also suggest the future directions of the UUV technologies based on the case analysis.

Optimization of suspension system of heavy off-road vehicle for stability enhancement using integrated anti-roll bar and coiling spring mechanism

Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.

General Torsional Stiffness Matching of Off-road Vehicle

Increasing frame torsional stiffness of off-road vehicle will lead to the decrease of body torsional deformation, but the increase of torsional loads of frame and suspension system and the decrease of wheel adhesive weight. In severe case, a certain wheel will be out of contact with road surface. Appropriate matching of body, frame and suspension torsional stiffnesses is a difficult problem for off-road vehicle design. In this paper, these theoretically analytic models of the entire vehicle, body, frame and suspension torsional stiffness are constructed based on the geometry and mechanism of a light off-road vehicle＇s body, frame and suspension. The body and frame torsional stiffnesses can be calculated by applying body CAE method, meanwhile the suspension＇s rolling angle stiffness can be obtained by the bench test of the suspension＇s elastic elements. Through fixing the entire vehicle, using sole timber to raise wheels to simulate the road impact on a certain wheel, the entire vehicle torsional stiffness can be calculated on the geometric relation and loads of testing. Finally some appropriate matching principles of the body, frame and suspension torsional stiffness are summarized according to the test and analysis results. The conclusion can reveal the significance of the suspension torsional stiffness on off-road vehicle＇s torsion-absorbing capability. The results could serve as a reference for the design of other off-road vehicles.

Analysis of Design Directions for Unmanned Surface Vehicles (USVs)

In recent years, because of the development of marine military science technology, there is a growing interest in the unmanned systems throughout the world. Also, the demand of Unmanned Surface Vehicles (USVs) which can be autonomously operated without the operator intervention is increasing dramatically. The growing interests lie in the facts that those USVs can be manufactured at much lower costs, and can be operated without the human fatigue, while can be sent to the hostile or quite dangerous areas that are inherently unhealthy for human operators. The utilization and the deployment of such vessels will continue to grow in the future. In this paper, along with the technological development of unmanned surface vehicles, we investigate and analyze the cases of already developed platforms and identify the trends of the technological advances. Additionally, we suggest the future directions of development.

Noise and vibration measurements in a Viking military vehicle

Noise and whole-body vibration measurements were made in a Viking military vehicle to determine the variation that should be expected during repeat measures,the effect of speed(up to 60 km/h in 5 km/h increments),and during travel over different types of terrain(comprising concrete road,gravel track and rough cross-country).Measurements were made at various crew positions(including the driver and commander)in both the front and the rear cabs in the vehicles.Three translational axes of vibration were measured in each seat.Two speeds were investigated over road(35 km/h and 55e60 km/h)and gravel(20 km/h and 35 km/h)surfaces.The effect of varying speed of the vehicle on the measured noise and vibration magnitudes was also investigated.The highest sound pressure level(LAeq)of 104 dB(A)was measured at the commander’s standing position during travel over concrete road at 55 km/h.Higher noise levels occurred for a standing commander compared with when sitting on the seat.A maximum single axis frequency-weighted vibration magnitude of 1.0 m/s^(2) r.m.s.was measured on the driver’s seat during travel over track at 35 km/h.Higher vibration magnitudes occurred during travel over track compared with travel over road.Both noise and vibration exposure of crew within the Viking vehicle increased with increasing speed of the vehicle.

Hopf Bifurcation Analysis and Control for Electrical System of Military Vehicle

Electrical system of military vehicle is a typical parameterized nonlinear system where complicated bifurcations may exist and threaten its safe and stable operation. An algebraic criterion for Hopf bifurcation is presented briefly and applied to find Hopf bifurcation point of the electrical system with automatic voltage regulator(AVR) dynamics in military vehicle. Hopf bifurcation controllers are designed for this electrical system by using wash-out filter,linear feedback,nonlinear feedback and their combination. The linear feedback control makes the system bring Hopf bifurcation at preferable parameter,the nonlinear feedback control modifies the type of the bifurcation,and the wash-out filter enhances the system damping,thus,the Hopf bifurcation is eliminated and the electrical system stability is ensured. Simulation results show the controller's validity.

Study on Modeling and Control Strategy for Electric Drive Motor of Tracked Vehicles

Aimed at the requirements for electric transmission system of a military tracked vehicle, the motor's design indexes were analysed and calculated. A model based on saturate inductance parameter of interior permanent magnet (IPM) synchronous motor was brought forward by using finite element analysis. And its control strategy based on the largest running capability was studied also. The experiment results for a scale model show that the modelling method improves the model's accuracy, and the motor's control strategy is effective.

Vehicle and terrain interaction based on Adams-Matlab co-simulation

A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.

基于光纤光栅“活塞式”封装的军用车辆振动传感研究

提出一种基于光纤光栅(fiber bragg grating,FBG)“活塞式”封装的军用车辆高可靠性振动传感器。FBG和圆柱体振子连接,并固定于圆柱体外壳的上下底面。圆柱体振子直径略小于圆柱体外壳内径,在外界振动信号激励下,振子带动FBG在圆柱体外壳内做“活塞式”往复运动,进而对FBG轴向应变产生调制。基于“活塞式”封装方式,振子被约束于外壳内,提高了传感器机械稳定性,避免了其他方向振动导致的测量误差。实验结果显示,传感器在0.1~0.7 g的振动加速度范围内的灵敏度为48.2 pm/g。公路路况车载试验下的振动信号较为平稳,最大加速度为±0.2g。河床路况车载试验下的振动信号成分更为复杂,最大振动加速度约为±0.4g,不同路况车载试验及模拟射击冲击下的实验结果与路况环境相符。

考虑不同路面特征的军用履带车辆循环工况构建

为全面有效地评估车辆动力系统的燃油经济性,建立考虑不同路面特征的履带车辆循环工况。收集铺面路、砂石路和起伏土路3种路面的实车运行数据作为原始数据样本,并利用小波分析对数据进行滤波处理。基于处理后的实车数据,综合利用主成分分析法、K均值聚类和马尔可夫链构建3种路面下的典型循环工况,并对构建的工况进行相似度分析。研究结果表明:采用新方法能够有效地构建出符合军用履带车辆运行特点的循环工况,3种路面下循环工况的特征均与原始数据有极高的相似度;3种路面车速-加速度联合概率分布与原始数据的均方根误差分别为0.0356、0.0039和0.0196,新构建的工况能够有效反映履带车辆的真实运行情况。

土壤对军用越野车辆机动性能影响分析

在软地面上的机动性能是军用高机动性越野车辆的主要性能之一,对于其野外作业有重要的战略意义。为了探究不同类型松软土壤地面路况对越野车辆机动性能的影响,基于离散元法对土壤进行建模,通过土壤堆积角测试试验以及土壤圆锥指数试验进行土壤刚度对标测试。通过DEM-MBD联合仿真方法,利用精确的土壤模型,对不可压缩干燥土壤、不可压缩湿润土壤、可压缩干燥土壤、可压缩湿润土壤4种不同类型土壤进行仿真分析,通过对比越野车辆平均速度、牵引力、驱动扭矩、轮胎沉陷量,探究土壤类型对越野车辆机动性能的影响。越野车在湿润土壤上比在干燥土壤上牵引力减少了6.98%,在不可压缩土壤上的稳定行驶速度比在可压缩土壤上稳定行驶速度高34.2%,在湿润的土壤路面上速度更加稳定。研究成果弥补了国内车辆地面力学领域土壤对整车机动性影响的空白,可为军车野外复杂地形(如沙地、雪地、泥泞等)作战时选择最优的行驶路面,提高作战效率。

军用混合动力汽车应用及展望

通过文献综述总结了军用混合动力汽车的优势,对比分析了国内外先进的军用混合动力汽车的性能和特点,梳理出现有军用混合动力汽车所具有的共性问题是:电池的安全性无法保障、电动机寿命易受恶劣环境影响较、成本较高。对军用混合动力汽车的发展趋势进行展望,研究表明:未来军用混合动力汽车性能更均衡、串联式构型加电动轮驱动是未来发展趋势、无人地面车辆将会在未来军事领域发挥重要作用。

军用车辆太阳辐射热效应模拟试验室设计

通过研究太阳辐射国内外相关试验测试标准,对比了不同标准中太阳辐射热效应试验温度、辐照度等指标要求,作为太阳辐射热效应模拟试验室的设计输入条件。针对军用车辆的特点,设计了太阳辐射热效应模拟试验室,该试验室可满足大尺寸军用车辆五面照射的试验需要,通过灯阵设计仿真与验证,试验室辐照度均匀度在10%以内。结合温度控制和太阳模拟系统联合控制,实现了太阳辐射日循环环境模拟,并结合A1干热地区指标要求进行了试验验证。通过试验测试表明,太阳辐射热效应模拟试验室均匀度和允差范围满足GJB 150.7A的设备要求,对军用车辆的太阳辐射热效应试验室设计具有参考价值。

A survey on multi-sensor fusion based obstacle detection for intelligent ground vehicles in off-road environments

With the development of sensor fusion technologies, there has been a lot of research on intelligent ground vehicles, where obstacle detection is one of the key aspects of vehicle driving. Obstacle detection is a complicated task, which involves the diversity of obstacles, sensor characteristics, and environmental conditions. While the on-road driver assistance system or autonomous driving system has been well researched, the methods developed for the structured road of city scenes may fail in an off-road environment because of its uncertainty and diversity.A single type of sensor finds it hard to satisfy the needs of obstacle detection because of the sensing limitations in range, signal features, and working conditions of detection, and this motivates researchers and engineers to develop multi-sensor fusion and system integration methodology. This survey aims at summarizing the main considerations for the onboard multi-sensor configuration of intelligent ground vehicles in the off-road environments and providing users with a guideline for selecting sensors based on their performance requirements and application environments.State-of-the-art multi-sensor fusion methods and system prototypes are reviewed and associated to the corresponding heterogeneous sensor configurations. Finally, emerging technologies and challenges are discussed for future study.

无人机航拍军事车辆实时检测及定位算法

针对地面高价值军事车辆难以实时观测定位的问题,提出无人机航拍军事车辆实时检测及定位算法。创建真实作战场景下的多类型多尺度航拍军事车辆目标检测数据集Armed_vehicle;在轻量级神经网络模型YOLOX-Tiny中引入大卷积核注意力模块,采用边框回归函数,达到85.82%的检测准确率,且在检测速率上具有优势;创新性地提出一种基于无人机可见光图像的单目视觉定位算法,在百米飞行高度上的目标平均定位误差为3.69 m,表明所提算法能准确地获取地面目标的地理位置,具有良好的综合性能与应用前景。

Off-road testing scenario design and library generation for intelligent vehicles

To realize the widespread application and continuous functional development of intelligent vehicles,test and evaluation of vehicle's functionality and Safety Performance in complex off-road scenarios are fundamental.Since traditional distance-based road tests cannot meet the evolving test requirements,a method to design the function-based off-road testing scenario library for intelligent vehicles(IV)is proposed in this paper.The testing scenario library is defined as a critical set of scenarios that can be used for IV tests.First,for the complex and diverse off-road scenarios,a hierarchical,structural model of the test scenario is built.Then,the critical test scenarios are selected adaptively according to the vehicle model to be tested.Next,those parameters representing the challenging test scenarios are selected.The selected parameters need to fit the natural distribution probability of scenarios.The critical test-scenario library is built combing these parameters with the structural model.Finally,the test scenarios that are most approximate to the natural driving scenario are determined with importance sampling theory.The test-scenario library built with this method can provide more critical test scenarios,and is widely applicable despite different vehicle models.Verified by simulation in the off-road interaction scenarios,test would be accelerated significantly with this method,about 800 times faster than testing in the natural road environment.

电喷发动机故障诊断与维修技术研究

为了提高发动机的维修质量,本文提出了发动机故障诊断方法研究,提出了发动机故障维修技术研究,通过传感器技术实时监测发动机的各种运行参数,随后,利用小波变换与分形理论对这些参数进行处理和分析,有效地提取出故障特征。通过计算振动信号的分形维数和盒维数,开发了基于离散小波变换(DWT)的故障诊断算法,通过对比实际运行数据与标准值或模型预测值,迅速准确地判断出发动机的故障类型和位置。

国外军用UUV发展现状与趋势

作为海洋无人化体系战争中重要的一员,水下无人潜航器(UUV)具有机动性好、隐蔽性强和智能度高等优点,被广泛应用于情报侦查、鱼雷反制以及反潜作战等军事任务中,军用UUV成为各国军事装备争相研制的热点装备之一。文章主要论述军用UUV的发展现状、系统组成以及关键技术,并从扩大军用UUV的应用范围和提高作战效能等方面分析其发展趋势。

混合动力技术在军用汽车上的应用

以BJ212军用轻型越野车为例,对其改为混合动力后的驱动型式、动力总成参数的确定以及性能预测等方面进行了初步探讨。结果表明,改变后的越野车易于实现纯电动行驶和停车发电的功能,更能适应野战部队的需要。与原车相比,最高车速提高30%,最大爬坡度提高34%,油耗降低30%,同时能在纯电动模式下以50km/h的速度行驶33.7km。