基于可拓决策法的车辆自适应避撞控制方法研究

车辆的避撞控制可以有效避免或缓解车辆的碰撞事故,是自动驾驶汽车的关键控制技术之一.各种交通条件、不确定的道路附着系数以及复杂的液压制动执行系统都会降低避撞控制的有效性.因此,本文提出了一种基于可拓决策法的自适应避撞控制,该控制方法对路面附着系数具有自适应性,并能够精确控制制动系统的制动液压力.首先,设计了滑模观测器来估计轮胎纵向力,并基于观测得到的轮胎纵向力,进一步提出带遗忘因子的递推最小二乘法估计道路附着系数.其次,基于递推最小二乘法的估计值,提出了基于路面附着系数自适应调节的自适应避撞控制方法,该方法基于可拓决策法的先决判定决定当前时刻应采用何种避撞控制策略,即采用可拓决策方法判断进行点刹预警制动、全制动或者不制动.再次,通过对执行系统-电控液压制动系统进行精确的液压控制,实现主动减速控制效果.最后,采用软件联合仿真手段对上述方法进行了验证,结果表明所提出的算法在避撞行驶工况中具有良好的避撞效果.

基于负泊松比结构的汽车B柱结构耐撞性优化设计

为了提高汽车的侧面耐撞性,基于传统B柱基本结构,提出了一种填充负泊松比内芯的新型B柱结构.根据我国新车评价规程C-NCAP要求,建立基于新型B柱结构的整车侧面碰撞模型;采用最优拉丁超立方试验设计法采取样本点,建立B柱各评价指标与设计变量之间的响应面模型;在此基础上,以B柱侵入位移和侵入速度为优化目标,采用NSGA-Ⅱ优化算法对新型B柱结构进行多目标优化设计.结果表明:新型B柱结构使得整车侧面碰撞的侵入位移下降了7.44%,侵入速度下降了5.10%,两者都有明显降低,这显著改善了汽车的侧面耐撞性能.

基于汽车车身制造工艺学课程的线上线下混合式教学方法研究

随着信息技术的不断进步,线上线下混合式教学模式已成为我国高等教育重要的发展方向,其以学生为中心和因材施教的理念弥补了传统教学模式的短板。线上、线下课程如何各司其职并进行深度融合是提高课程质量的关键,该文以汽车车身制造工艺学课程为基础,探究了线上线下混合式教学中采用的“任务驱动型”“传统型+研究型”和基于“教师—学生—助教”反馈机制的教学方法,以促进学生学习个性化、自主性和探究性的发挥,锻炼学生的创新实践能力,培养学生的团队意识,整体提升课程质量。

基于自适应容积粒子滤波的车辆状态估计

针对车辆状态估计中由模型的强非线性、噪声的非高斯分布等相关因素导致估计精度下降甚至发散的问题,本文提出了基于自适应容积粒子滤波(Adaptive cubature particle filter,ACPF)的车辆状态估计器。首先基于非稳态动态轮胎模型,构建高维度非线性八自由度车辆模型。其次利用自适应容积卡尔曼滤波(Adaptive cubature Kalman filter,ACKF)算法更新基本粒子滤波(Particle filter,PF)算法的重要性密度函数,以完成自适应容积粒子滤波算法设计。利用车载传感器信息,运用ACPF算法实现对车辆的侧倾角、质心侧偏角等关键状态变量高精度在线观测。搭建Simulink-Carsim联合仿真平台进行了算法的验证,结果表明该算法状态估计精度高于传统无迹粒子滤波(Unscented particle filter,UPF)算法,且算法运算效率高于UPF算法,而传统PF估计值发散。研究结果为实现车辆动力学精准控制提供了理论支持。

A型纯电动客车EHPS助力电机转速控制优化

针对A型纯电动客车EHPS助力电机恒定高速运转的问题,本文设计理想转向盘力矩曲线,建立A型纯电动客车的整车模型和EHPS系统模型,推导出理想EHPS助力特性曲线,得到各车速及转向盘转角下的目标电机转速。基于Simulink和AMESIM对模型进行联合仿真,仿真结果表明:助力电机转速控制优化后的EHPS能满足车辆低速转向时的轻便性和高速转向时驾驶员的路感,并改善节能性。

犹他游动放线菌SW1311中阿库来菌素A酰基酶在棘白菌素类抗真菌药物合成中的应用(英文).

棘白菌素类抗真菌药物米卡芬净和阿尼芬净的合成工艺中包括一个关键步骤:水解除去FR901379分子和棘白菌素B(echinocandin B,ECB)分子的脂肪酸侧链,形成环状的6元多肽核心。FR901379和ECB的水解可以分别被FR901379酰基酶和阿库来菌素A酰基酶(aculeacin A acylase,AAC)催化,因此,FR901379酰基酶和AAC的发掘、表征和生产在米卡芬净和阿尼芬净的工业生产上具有重要的应用价值。本研究首先筛选到了犹他游动放线菌SW1311,发现该菌株发酵液具有酰基酶活性,并摸索了不同发酵条件对酰基酶活性的影响。然后将犹他游动放线菌SW1311中的AAC基因克隆到改造过的质粒载体p IJ8660中,并将该质粒转化到天蓝色链霉菌(Streptomyces coelicolor)A3(2)中对AAC基因进行高表达,得到重组菌株sSCO-AAC。最后将sSCO-AAC生产的AAC活性和所需培养时间与犹他游动放线菌SW1311进行比较,表征了sSCO-AAC的发酵液水解FR901379的反应。结果表明,犹他游动放线菌SW1311中的酰基酶具有水解FR901379和青霉素V的酰基活性。用重组菌株sSCO-AAC生产的AAC活性比犹他游动放线菌SW1311的高4.6倍,且该重组菌株所需的培养时间比犹他游动放线菌SW1311缩短了30%。该结果不仅将ACC的应用范围从阿尼芬净合成拓宽到了米卡芬净合成,而且还揭示出天蓝色链霉菌A3(2)可以作为一个良好的AAC表达菌株。本研究对阿尼芬净和米卡芬净的工业化生产具有潜在的应用价值。

Tracking Performance of Electric Power Steering System Based on the Mixed H_2/H_∞ Strategy

The tracking performance of motor current is an important factor that affects the assistance torque of electric power steering （EPS） system. Bad tracking performance will cause assistant torque delay, and make road feeling bad, and is influenced by the input steering torque and system measuring noise. However the existing methods have some shortages on system＇s robust dynamic performance and robust stability. The mixed H2/H∞ strategy for recirculating ball-type EPS system in a pure electric bus is proposed, and vehicle dynamic model of the system is established. Due to the existence of system model uncertainty, disturbance signals, sensor noises and the demand of system dynamic performance, the indexes of robust performance and road feeling for drivers are defined as the appraisal control objectives. The H∞ method is introduced to design the H∞ controller, and the H2 method is applied to optimize the H∞ controller, thus the mixed H2/H∞ controller is designed. The response of EPS system to the motor current command with amplitude of 20 A, the road disturbance with amplitude of 500 N and the sensor random noise with the amplitude of 1 A is simulated. The simulation results show that the recirculating ball-type EPS system with the mixed H2/H∞ controller can attenuate the random noises and disturbances and track the boost curve well, so the mixed H2/H∞ controller can improve the system＇s robust performance and dynamic performance. For the purpose of verifying the performance of the designed control strategy, the motor current tracking performance ground tests are conducted with step response input of the steering wheel, double-lane steering test and lemniscate steering test, respectively. The tests show that the mixed H2/H∞ controller for the recirculating ball-type EPS system of pure electric bus is feasible. The designed controller can solve the robust performance and robust stability of the system, thus improve the tracking performance of the EPS system and provide satisfied road feeling for the drivers.

Local Path Planning and Tracking Control of Vehicle Collision Avoidance System

Automotive collision avoidance technology can effectively avoid the accidents caused by dangerous traffic conditions or driver's manipulation errors.Moreover,it can promote the development of autonomous driving for intelligent vehicle in intelligent transportation.We present a collision avoidance system,which is composed of an evasive trajectory planner and a path following controller.Considering the stability of the vehicle in the conflict-free process,the evasive trajectory planner is designed by polynomial parametric method and optimized by genetic algorithm.The path following controller is proposed to make the car drive along the designed path by controlling the vehicle's lateral movement.Simulation results show that the vehicle with the proposed controller has good stability in the collision process,and it can ensure the vehicle driving in accordance with the planned trajectory at different speeds.The research results can provide a certain basis for the research and development of automotive collision avoidance technology.

Torque Distribution of Electric Vehicle with Four In-Wheel Motors Based on Road Adhesion Margin

With the worsening of energy crisis and environmental pollution,electric vehicles with four in?wheel motors have been paid more and more attention. The main research subject is how to reasonably distribute the driving torque of each wheel. Considering the longitudinal motion,lateral motion,yaw movement and rotation of the four wheels,the tire model and the seven DOF dynamic model of the vehicle are established in this paper. Then,the torque distribution method is proposed based on road adhesion margin,which can be divided into anti ? slip control layer and torque distribution layer. The anti?slip control layer is built based on sliding mode variable structure control,whose main function is to avoid the excessive slip of wheels caused by road conditions. The torque distribution layer is responsible for selecting the torque distribution method based on road adhesion margin. The simulation results show that the proposed torque distribution method can ensure the vehicle quickly adapt to current road adhesion conditions,and improve the handling stability and dynamic performance of the vehicle in the driving process.

民法典视域下哲学客体、法学客体与人格权客体辨析

《中华人民共和国民法典(草案)》公布后,其中的人格权编争议较大,争议问题聚焦于人格权的客体,对人格权客体质疑又溯源于哲学客体。在哲学发展史上,关于主体与客体的关系和界分,在不同阶段有不同的认识。近代哲学使主体和客体彻底对立,这是本体论哲学观,该观点影响到西方民法上人格权的立法,也影响到我国人格权立法的制度设计。在后现代认识论哲学上,凡相互存在某种关系的事物或存在,均可以成立主、客体关系。关于法学上的客体——法律关系客体和权利客体之间的关系以及它们各自的客体是什么,学术界未见统一说法。不论是法律关系客体还是权利客体首先必须是具体的,笔者支持“多客体说”。法律关系客体与权利客体是相同的。虽然哲学上的客体与法学上的客体在本体论上不同,但在认识论上二者可以高度统一。人格权的客体就是各种人格要素,除身体权外,人格权的客体均为精神存在而非物质实体,但却是客观存在的,完全符合哲学上客体生成的要件。人格利益权利化是没有“客体”障碍的。

四轮分布式线控转向系统稳定与协调控制研究

四轮分布式线控转向车辆拥有四个独立控制的车轮,在行驶过程中受到外界干扰时容易导致四个车轮转角响应不同步,从而影响车辆行驶稳定性。提出一种分层式四轮分布式线控转向系统稳定与协调控制策略,上层采用模型预测控制算法计算参考四轮转角对理想的横摆角速度和质心侧偏角进行跟踪从而实现车辆的稳定性控制,下层采用超扭转二阶滑模控制算法跟踪上层计算出的参考车轮转角,提高执行机构响应速度和精度,消除干扰影响。通过Carsim和Matlab/Simulink联合仿真对提出的稳定与协调控制策略进行不同工况下的仿真验证。结果表明,在受到外界干扰时,所提出的稳定与协调控制策略能够大幅降低转向执行机构的跟踪时延,提高横摆角速度和质心侧偏角的跟踪效果,有效提升四轮分布式线控转向车辆的稳定性。

基于Bi-GLSTM网络的车辆驾驶意图分析与识别

驾驶意图识别能有效提高自车对其他交通参与者的轨迹预测能力,是实现智能车自主决策和规划的基础。然而动态复杂交通环境下周围车辆的交互是实现准确可靠驾驶意图识别亟待解决的挑战之一。为提高在动态复杂交通场景下驾驶意图识别的准确率,提出基于双向图长短时记忆网络(Bidirectional graph long short term memory,Bi-GLSTM)网络的驾驶意图时序识别模型。首先基于局部加权回归散点平滑法对原始数据集中的位置、速度和加速度进行平滑处理,并联合纵横向运动参数为数据标注驾驶意图;然后建立图注意力神经网络,分析和提取周围车辆与目标车辆之间的交互特征,嵌入注意力机制,分析周围车辆对目标驾驶意图的重要性,增强模型对相关性较大的车辆运动状态关注程度;融合周围车辆交互特征和目标车辆历史运动特征,为提高模型在动态复杂交通环境下的鲁棒性和可靠性,基于双向长短时记忆网络提取特征之间的时序特征;最后在公开数据集HighD上训练并验证模型的有效性,结果表明相比于图神经网络、循环神经网络等模型,识别准确率分别提高了11.33%、55.31%;通过可视化注意力权重,说明所提出的模型也一定程度上解决了可解释性问题。

考虑交互博弈的无信号交叉路口自动驾驶车辆决策规划研究

为了解决无信号交叉路口自动驾驶车辆决策保守,与周围车辆交互性差的问题,提出一种考虑交互博弈的无信号交叉路口自动驾驶车辆决策规划算法。该方法分为以下几步,首先基于运动学模型及道路约束对自车和周围车辆进行初步的运动预测,并建立两车的交互动作空间,得到车辆可能的行驶域。其次,建立一个新颖的危险度评估方法,能评估两车在任意位置、任意姿态、任意速度下的碰撞危险度,用于各交互动作状态行为值的求解。进一步基于斯塔克伯格主从博弈求出两车的均衡动作策略,该策略即为当前交通环境下考虑交互得到的最优动作。最后,通过Prescan/Simulink构建交叉路口场景进行联合仿真,来验证该算法的合理性。结果表明所提出的考虑交互博弈的算法在保证安全性的基础上,能相对于基于决策树和无交互的方法分别提高7.3%和12.4%的效率,并能在多车复杂工况下与周围车辆进行灵活交互。

分布式驱动电动汽车关键技术及产业化展望

中国科协第390次青年科学家论坛--分布式驱动电动汽车关键技术与产业化前景于2019年11月29-30日在北京举行。此次论坛由中国机械工程学会承办,《机械工程学报》编辑部JME学院和北京理工大学电动车辆国家工程实验室协办。本文为论坛主席及5位执行主席根据研讨情况,对分布式驱动电动汽车关键技术及产业化趋势和方向进行的预判。

组喷孔喷嘴对双对置柴油机喷雾及燃烧的影响

针对双对置柴油机混合气形成困难的特点,采用CONVERGE CFD软件,建立双对置柴油机数值仿真模型。设计3种汇聚型组喷孔喷嘴的喷孔布置方案,研究在保持喷油压力不变的前提下,对3种方案下喷雾、混合气形成和燃烧过程进行分析。结果表明:与传统喷嘴相比,改进后的组喷孔喷嘴对喷雾贯穿距影响较小,有利于缸内湍流动能的提高,加快缸内混合气的形成速率。同时,组喷孔喷嘴使燃油分布更加均匀,分布区域也更广,有利于改善油气混合质量,提高双对置发动机气缸压力和燃烧效率,达到提升双对置发动机性能的效果。其中,第3种组喷孔布置方案下发动机指示功率可提高7.6%。

Control strategy of a novel electric power steering system integrated with active front steering function

A novel electric power steering system(EPS) integrated with active front steering(AFS) is developed.It has functions of both AFS system and EPS system with two actuator units:the AFS actuator unit and the EPS actuator unit.The AFS actuator unit controls the displacement transfer behavior of the steering system,and improves the handling stability under adverse road conditions by varying the steering ratio directly related to the speed and road conditions.The EPS actuator unit controls the force transfer behavior of the steering system,and improves the steering portability and road feel of the vehicle.Based on a dynamic model,the mixed H2/H∞ control strategy of the EPS actuator and the active steering intervention control strategy of the AFS actuator are designed.The simulation indicates that the novel EPS system with the designed control strategies has obvious advantages in vehicle handling stability and the driver's road feel over the traditional EPS system,and extends the vehicle's steering performance.

Primary studies on integration optimization of differential steering of electric vehicle with motorized wheels based on quality engineering

The model of the differential steering system(DSS) of electric vehicle with motorized wheels and the three-degree-of-freedom dynamic model of vehicle are built.Based on these models,the concepts and quantitative expressions of steering road feel,steering portability and steering stability are proposed.Through integrating the Monte Carlo descriptive sampling,elitist non-dominated sorting genetic algorithm(NSGA-II) and Taguchi robust design method,the system parameters are optimized with steering road feel and steering portability as optimization targets,and steering stability and steering portability as constraints.The simulation results show that the system optimized based on quality engineering can improve the steering road feel,guarantee steering stability and steering portability and thus provide a theoretical basis for the design and optimization of the electric vehicle with motorized wheels system.

Path planning and stability control of collision avoidance system based on active front steering

Vehicle collision avoidance system is a kind of auxiliary driving system based on vehicle active safety,which can assist the driver to take the initiative to avoid obstacles under certain conditions,so as to effectively improve the driving safety of vehicle.This paper presents a collision avoidance system for an autonomous vehicle based on an active front steering,which mainly consists of a path planner and a robust tracking controller.A path planner is designed based on polynomial parameterization optimized by simulated annealing algorithm,which plans an evasive trajectory to bypass the obstacle and avoid crashes.The dynamic models of the AFS system,vehicle as well as the driver model are established,and based on these,a robust tracking controller is proposed,which controls the system to resist external disturbances and work in accordance with the planning trajectory.The proposed collision avoidance system is testified through CarSim and Simulink combined simulation platform.The simulation results show that it can effectively track the planning trajectory,and improve the steering stability and anti-interference performance of the vehicle.

Mixed H_2/H_∞ road feel control of EPS based on genetic algorithm

In view of the existence of uncertainties such as system model and disturbance signal in the electric power steering(EPS) sys-tem,and the demand for system dynamic performance,the mixed H2/H∞ controller based on genetic algorithm is proposed.In order to obtain satisfactory steering feel,robust performance and steering stability,models of EPS system and a two-degree-of-freedom car are set up,then the state space model and the augmented matrixes are built.The H∞ method is introduced to minimize the effect of disturbances on the outputs,and the H2 method is applied to optimizing the system performance based on genetic algorithm.The simulation results show that the modified mixed H2/H∞ controller,which synthesizes the advantage of H2 control and H∞ control,has better robust performance and robust stability.The designed controller can attenuate the noises and disturbances caused by road random motivation,torque sensor measurement and model parameter uncertainty,ena-bling the driver to obtain satisfactory road feel.

Multidiscipline collaborative optimization of differential steering system of electric vehicle with motorized wheels

Based on the multidiscipline design optimization theory, a multidiscipline collaborative optimization model of the differential steering system of electric vehicle with motorized wheels is built, with the steering economy as the main system and the steering road feel, the steering flexibility and the mechanic character of the steering sensors as the subsystems. Considering the coupled relationship of each discipline, the main system is optimized by the multi-island algorithm and the subsystems are optimized by the sequential quadratic programming algorithm. The simulation results show that the steering economy can be optimized by the collaborative optimization, and that the system can get good steering road feel, good steering flexibility and good mechanic character of the steering sensors.