【作者】 殷卫乔；

【导师】 李幼德；

【作者基本信息】 吉林大学 ， 车辆工程， 2014， 博士

【摘要】 随着经济的发展我国汽车保有量逐年增加，每年因交通事故造成了巨大的经济损失和人员伤亡，车辆的安全性能越来越受到关注。伴随着汽车电子技术的进步，汽车底盘控制系统得到了快速发展并被广泛应用,提高了车辆的行驶安全性。当车辆上同时安装多个控制系统时，会导致车辆结构十分复杂，传感器和执行器数目过多，部分系统功能存在重叠或控制目标存在冲突。如果不对这些系统进行协调控制，可能会导致车辆的整体性能下降。近年来车辆自动化程度越来越高，X-by-wire系统逐渐在车辆得到应用。该项技术降低了机械系统的复杂程度，使车辆布置更灵活，最重要的是更容易实现转向系统、制动系统以及悬架系统等底盘系统的集成控制。因此，针对线控系统的协调控制成为车辆底盘控制领域研究的热点。线控系统集成控制效果的影响因素有两个方面：一方面是软件上协调控制各子系统的算法，另外一个方面是硬件上对线控执行机构控制的精确程度。针对上述问题，本文结合教育部霍英东基金资助项目“汽车智能集成电控制动系统研究”、国家自然科学基金资助项目“基于线控制动的汽车动力学控制研究”以及“汽车电控分时制动调压装置的关键科学问题与关键技术”。在总结国内外研究成果的基础上，以某轻型汽车为研究对象，开展基于线控执行机构精细调节的转向/制动控制系统的研究。针对线控执行机构进行理论分析和仿真研究，提出了线控执行机构的精细调节方法。建立了主动转向和主动制动系统集中式控制结构框架，采用非线性模型预测控制方法设计了主动转向/制动控制算法，利用模糊控制理论设计了线控转向和线控制动控制器。建立了包含线控转向和线控制动系统的车辆动力学模型，自主设计并搭建了目标车辆的线控转向/制动协调控制离线仿真平台以及硬件在环试验台，分别进行了离线仿真分析和硬件在环试验，验证了所设计的转向/制动控制算法。本文主要内容包括：1、建立基于线控系统的车辆动力学模型根据本文集成控制系统控制策略研究需要，建立了十五自由度非线性车辆动力学模型。整车模型包括簧载质量的六个自由度（纵向、侧向、垂向、侧倾、俯仰和横摆转动）、非簧载质量的四个垂向振动、前轮转向和四个车轮的旋转运动，以及辅助计算模块、轮胎模型、驾驶员模型和线控系统模型等，为搭建转向/制动离线仿真平台和硬件在环试验台奠定了基础。2、线控执行机构精细调节方法研究线控执行机构的控制精度是影响底盘集成控制效果的关键因素之一。本文针对线控执行机构——永磁无刷直流电机建立数学模型，并在MATLAB/SIMLINK下建立无刷直流电机模型。通过仿真分析得出对无刷直流电机PWM控制时，由于相电流在换相和非换相时刻均存在波动，进而导致转矩的波动。接着分析了对无刷直流电机采用不同PWM调制方式控制时，换向期间非换相相上电流波动和非换向期间导通相上电流波动；最后分析了本文采用的pwm-on-pwm调制方式时无刷直流电机的动态性能；提出30°电角度控制的数字实现方法；最后通过对比仿真验证控制效果。所提出30°电角度的数字估算方法，在不增加成本的条件下得到30°电角度时刻。所采用的pwm-on-pwm调制方式不增加开关损耗的同时有效的抑制了转矩的波动，实现对线控执行机构——无刷直流电机转矩的精细调节，为线控系统转向/制动高层控制器的开发奠定基础。3、线控转向和制动协调控制研究设计了针对线控转向和制动稳定性控制算法整体结构。提出适用于初始工作点位于平衡点或非平衡点的非线性模型控制算法。采用用非线性四轮三自由度的车辆模型为参考模型设计了非线性模型预测控制算法，以纵向速度、横摆角度、横摆角速度和侧向位移为控制目标，求解了优化的控制输入主动前轮转角和主动四轮制动力；利用模糊控制规律实现执行层制主动前轮转角和主动制动力的调节，完成主动转向和主动制动的综合协调控制算法。4、离线仿真平台搭建及离线仿真分析根据车辆动力学模型和主动转向主动制动稳定性控制算法，利用Matlab软件搭建离线仿真平台。仿真平台包括车辆动力学仿真软件和控制算法Simulink模块、仿真平台图形界面。该平台将离线仿真控制、参数调节和数据后处理有机结合，使控制算法参数调节更便捷。利用所搭建的离线仿真平台，进行了阶跃转向、正弦转向工况和方波渐增转向下的离线仿真。试验结果表明：本文设计的转向/制动协调控制系统能够有效的消除主动转向和主动制动系统的干涉，显著提高车辆的操纵稳定性能。5、硬件在环试验台搭建及试验研究为了进一步验证本文设计的线控转向/制动控制系统的有效性，设计了基于线控系统的硬件在环试验台方案，搭建了基于dSPACE实时仿真平台线控转向/制动控制硬件在环试验台。在试验条件下模拟车辆运行的实际运行环境，减小线控转向/制动控制系统开发中对道路试验的依赖，降低成本和缩短开发周期。试验台包括实时平台、硬件系统和软件部分，对硬件系统各部分进行了选型和设计。在搭建的硬件在环试验台上进行了典型工况的硬件在环试验。试验结果表明：线控系统硬件在环试验台软、硬件匹配合理；本文设计的基于线控的转向/制动系统实现了线控执行机构的精细调节，具有良好的控制效果，能够有效的提高车辆的操纵稳定性。更多还原

【Abstract】 China’s vehicle population has increased every year with the economic development,huge economic losses and casualties have been made because of traffic accidents each year,people take more and more attention to safety performance of vehicle. Accompanied byadvances in vehicle electronic technology, vehicle chassis control system have beendeveloping rapidly and is widely used, which improve the driving safety of vehicle. Whenmultiple control systems installed on the vehicle, which will lead to the vehicle structure isvery complex, the number of sensors and actuators is excessive, part of the system functionsis overlapped or exists control target conflict. Without coordinated control to these systems,the overall performance of the vehicle decreased. The degree of automation is graduallyincreased in recent years, X-by-wire system gradually been applied in the vehicle. Thistechnology reduces the complexity of the mechanical system, which makes arrangement ofthe vehicle more flexible, the most important thing is easier to achieve integrated chassiscontrol for the steering systems, suspension systems, braking systems. Accordingly,coordinated control of by-wire system has become a focus in vehicle chassis control research.The integrated control effect factors of by-wire systems have two aspects: one is thealgorithm of coordinated control subsystems in software, the other is the precision of by-wiresystem actuators control in hardware.In response to these problems, this paper is combined with Ministry of educationHenry Fok funded project “Vehicle intelligent integrated electric control system research”,NFSC project“Research on vehicle dynamics control based on brake-by-wire”,“The keyscientific issues and key technologies of vehicle electronic control timeshare brake pressure regulating device”. Based on the summery of domestic and foreign research results, thispaper takes a light vehicle as the research object and conducts steering/braking controlsystem research base on accurate regulation of by-wire actuators. Based on theoreticalanalysis and simulation experiment on by-wire actuators, accurate regulation method ofby-wire actuators is proposed. Centralized control structure framework of active steering andactive braking system is established, it uses nonlinear model predictive control methoddesigned active steering/braking control algorithm, it uses fuzzy control theory designedsteer-by-wire and brake-by-wire controller. Vehicle dynamics model includes steer-by-wireand brake-by-wire systems is established, steer-by-wire and brake-by-wire coordinatedcontrol offline simulation platform and hardware in the loop test platform of target vehicle isindependently designed and built, off-line simulation and hardware in the loop test werecarried out to verify the steering/braking control algorithm which has been designed.The main contents include:1. Establishing the vehicle dynamics model based on by-wire systemAccording to the requirements of integrated control system strategy, a fifteen degree offreedom nonlinear vehicle dynamics model has been established. Vehicle model includes sixdegrees of freedom for sprung mass (longitudinal, lateral, vertical, roll, pitch and yawmotion), the four vertical vibration degrees of freedom for the unsprung mass, the frontwheel steering and the rotation of four wheels, and an auxiliary calculation module, tiremodel, the driver model and by-wire system models, which provided the foundations forbuilding of the steering/braking offline simulation platform and hardware in the loop testplatform.2. By-wire actuators accurate regulation methodThe precision of by-wire actuators is a key factor to influence the control effect ofintegrated chassis control.Mathematical model of by-wire actuators--brushless DC motorwas built in this paper, and established a brushless DC motor model in MATLAB/SIMLINK. The simulation analysis results indicate when pulse width modulation (PWM)method is used to control the brushless DC motor, phase current fluctuations exists at commutation and non-commutation time, leading to fluctuations in torque. Then analyzedusing different PWM modulation control brushless DC motor, Non-commutation existsphase current fluctuations during commutation period and the conduction phase currentexists phase current fluctuations during non-commutation period. Finally, the dynamicperformance of brushless DC motor when used pwm-on-pwm modulation has been analyzed.30°electrical angle digital implementation method was raised. Finally, comparing thesimulation result verified control effect. Using the proposed30°electrical angle digitalimplementation method obtained30°electrical angle moment at no additional cost.Pwm-on-pwm modulation without increasing switching losses effectively inhibited torquefluctuations, achieved accurate regulation of by-wire actuators--brushless DC motor torque,which provided the foundations for building of the steering/braking by-wire systemsuperior controller development.3. Steering/braking by-wire system coordinated controlThe overall structure of steering/braking by-wire stability control algorithm wasdesigned in this paper. Nonlinear model control algorithm was raised which applied to theinitial balanced point and non-balanced point. Nonlinear model predictive control algorithmwas designed by using nonlinear four wheel three degrees of freedom vehicle model as areference model. The algorithm used longitudinal speed, yaw angle, yaw rate and lateraldisplacement as the control target to solve optimized control input for active front corner andactive four braking force. This paper achieved regulation of active front steering and activebraking force in execution layer by using fuzzy control, and completed a comprehensivecoordinated control algorithm of active steering and active braking.4. Constructing offline simulation platformAccording to the vehicle dynamics model and active steering and active brakingstability control algorithm, this paper built up offline simulation platform by using Matlabsoftware. Simulation platform including vehicle dynamics simulation software, controlalgorithms Simulink module and simulation platform graphical interface. The platformcombined the off-line simulation control and parameter adjustment and data post-processing well, which made the control algorithm parameter adjustment more convenient. Offlinesimulation of step steering, sine steering and square wave incremental steering were carriedout on offline simulation platform.The results showed that: the designed steering/braking coordinated control system caneffectively eliminate active steering and active braking system interference, which cansignificantly improve the vehicle steering stability.5. Building hardware in the loop test platform and experiment researchIn order to verify the effectiveness of the designed steering/braking by-wire controlsystem, the by-wire control system hardware in the loop test platform program wasdesigned, a steering/braking control hardware in the loop test platform was built based ondSPACE real-time simulation platform. This paper simulated the vehicle actual operatingenvironment under the test conditionsand, which reduced the dependent on road tests insteering/braking by-wire control system development, which reduced costs and shorten thedevelopment cycle. Test platform including real-time platform, hardware and softwarecomponents, this paper selected and designed various parts of a hardware system. Typicalconditions were performed on the hardware in the loop test platform.The results showed that: the software and hardware of by-wire system hardware in theloop test platform matched reasonable. The designed steering/braking by-wire systemachieved accurate regulation of by-wire actuators, which has good control effect, it caneffectively improve the vehicle handling stability.更多还原