车辆自适应巡航分层控制系统的联合仿真研究

为改善车辆自适应巡航控制（ACC）系统的功能并使其控制系统的性能更加完善,本文中研究一种ACC系统建模和分层控制方法。采用Prescan与Simulink建立了一种车辆纵向动力学模型,设计了具有上、下两层结构的自适应巡航控制系统,控制器基于Matlab/Simulink进行建模,上层结构通过最优控制理论计算出理想的期望跟车加速度,下层结构将期望跟车加速度作为输入量对车辆进行相应的加速和减速控制,通过对汽车距离差和相对速度的计算和推理,实时调整本车加速度。结果表明,所建立的巡航控制系统可以较好的实现车辆自适应巡航功能,并且保证良好的跟踪性、安全性和适应性。该控制算法具有响应速度快、超调量小、能够消除系统偏差等优点。     

定速巡航分层控制策略硬件在环研究

为了提高车辆在行驶过程中的安全性与舒适性,减轻驾驶员的负荷,提出一种定速巡航分层控制策略,该策略将巡航工况分为几种不同的巡航模式,通过调节发动机的转速实现车速的控制。在上层控制中研究巡航控制模式决策问题,检查所要进入的巡航模式是否被允许;在中层控制中研究巡航退出条件是否成立,如果成立,则退出巡航,如果不成立则继续按照原来的控制策略进行巡航;在下层控制器中研究车辆实际巡航控制,运用增量式PID调节来控制车辆巡航目标速度、车辆实际速度、发动机的转速等。在此基础上,对所搭建的定速巡航分层控制策略进行实车硬件在环验证,主要验证减速-保持模式、加速-保持模式、加速—减速—阶升模式。试验结果表明,所开发的定速巡航分层控制策略,可实现车辆按照驾驶员的意图进行巡航过程中加减速的目的,并且巡航控制子模式与主模式的实际切换符合策略要求,能够提高整车的安全性与舒适性。     

带启停巡航功能的全速自适应巡航控制器的设计

带启停巡航功能的全速自适应巡航控制是研究自动驾驶系统的基础。提出了一种分层控制方法实现全速巡航功能:上层控制器基于线性二次型最优控制的车辆自适应巡航控制系统;并在该系统之上分析启停巡航控制的运动特征,对车辆起步时的加速度进行修正,改变控制器的参数,实现了启停巡航控制;设计了一种启停巡航功能和ACC平滑过渡的方法;下层控制器来实现上层控制器的期望加速度。采用车辆动力学仿真软件Carsim与Matlab/Simulink联合仿真并将控制逻辑编写为C语言代码然后下载至实车控制器进行实车试验,试验结果与仿真结果表明所设计的控制器既能满足启停巡航控制平稳起步与制动停车的要求,同时满足高速ACC的较小跟踪距离误差和速度误差,证明了所设计控制器的有效性和实用性。     

液压马达式汽车主动稳定杆系统建模与控制

以液压马达式主动稳定杆系统为研究对象,推导得到了液压马达式主动稳定杆的非线性动力学模型。利用线性化反馈的滑模控制方法设计了其控制器,并利用Lyapunov理论对控制系统的稳定性进行了证明。通过CarSim和MATLAB/Simulink对主动稳定杆系统进行了联合仿真,得出安装液压马达式主动稳定杆系统的车辆在双移线工况下运行的响应曲线。为了验证设计的控制方法,进行了实车试验。结果表明,与被动稳定杆相比,主动稳定杆系统具有较好的抗侧倾特性以及乘坐舒适性。     

城市工况汽车智能巡航控制与仿真

为改善或提高汽车行驶安全性及驾驭汽车的轻松舒适性,提出了基于城市工况的汽车智能巡航控制方法,建立了汽车纵向系统动力学模型。以巡航车与前车的理想安全距离与实际相对距离差及两车的相对速度差作为巡航控制变量,设计了智能巡航模糊逻辑控制器,实现了巡航车辆节气门开度与制动踏板行程的自动调节。利用MATLAB/Simulink建立了智能巡航仿真模块,并以城市工况下低速智能跟随工况为例进行了仿真。结果表明:该方法有效地实现了巡航车智能跟随前方车辆,并保证两车的安全行驶车距。     

非完整约束多轴驱动车辆的路径跟踪控制

针对具有非完整约束特性的多轴驱动车辆,分析多轴驱动形式下的转向几何关系及其运动学约束关系并建立动力学方程,采用基于制导路径跟踪理论的方法评价跟踪误差,推导消除误差所需的姿态角和路径参数更新公式;通过设计李亚普诺夫函数进行稳定性分析,证明了系统的全局一致渐进稳定性;采用非线性状态反馈精确线性化方法导出线性化的车辆动力学模型,在此基础上设计带有干扰观测器的滑模变结构速度跟踪控制器,并采用典型运动路径进行路径跟踪的仿真测试。仿真结果表明,所提出的跟踪控制策略能够满意地实现多轴驱动车辆对给定目标路径的跟踪。     

转向缸系统反馈线性化分析与系统解耦

为解决汽车转向缸加载控制中出现的诸如强位置干扰、多通道耦合、非线性等问题,将线性系统和非线性系统理论引入系统控制器的设计中,对各通道耦合问题开展了以前馈补偿为基础的解耦控制,所设计的前馈补偿结构简单,解耦网络阶次低;针对非线性问题提出了将非线性系统精确反馈线性化与最优控制相结合的方法,设计了基于精确反馈线性化的最优控制器,该方法将复杂的非线性系统问题转化为线性系统的综合问题,采用渐近输出跟踪方法实现系统控制。仿真结果表明:采用前馈补偿解耦控制器可以有效消除耦合,但当系统存在高度非线性时,仅采用前馈补偿解耦控制不能达到高品质的性能要求,而进一步设计的基于精确反馈线性化的最优控制器考虑系统非线性时,系统能快速、准确达到预置设定。     

直线电动机驱动3-DOF磁浮平台推力解耦控制

介绍一种新型的磁悬浮平台,应用多变量非线性的逆系统理论,对直线电动机驱动的磁悬浮平台这一多变量、非线性和强耦合的对象通过状态反馈线性化实现动态解耦控制,使其成为三个子系统。同时借助干扰观测器对扰动实现完全抑制。仿真结果表明,这种控制方案有良好的动态、静态特性和鲁棒性。     

悬臂梁非线性振动的压电分阶最优控制

提出非线性的分阶最优控制策略,并将其应用于悬臂梁非线性振动的压电减振控制.建立悬臂梁非线性压电减振系统动力学模型,导出减振系统的非线性动力学运动微分方程.将梁振动挠度和压电驱动器的控制电压同时展开为小参数形式,利用摄动法实现非线性压电控制微分方程的线性化.通过空间解耦,得到状态空间方程.设计非线性分阶控制器,对该减振系统进行分阶最优控制.     

智能车辆自适应巡航控制系统建模与仿真

为实现智能车辆的自适应巡航功能,基于模糊逻辑和滑模控制理论设计了具有上下两层结构的自适应巡航控制系统。通过对节气门开度和制动压力进行协调控制,使智能车辆能准确跟踪期望加速度。同时,构建了用于保证该系统控制协调性的切换逻辑曲线。仿真结果表明,自适应巡航控制系统能够使智能车辆在加速行驶、车辆跟踪和制动减速等行驶工况下保持良好的跟踪性和适应性。     

Adaptive cruise control with stop&go function using the state-dependent nonlinear model predictive control approach

In the design of adaptive cruise control (ACC) system two separate control loops - an outer loop to maintain the safe distance from the vehicle traveling in front and an inner loop to control the brake pedal and throttle opening position - are commonly used. In this paper a different approach is proposed in which a single control loop is utilized. The objective of the distance tracking is incorporated into the single nonlinear model predictive control (NMPC) by extending the original linear time invariant (LTI) models obtained by linearizing the nonlinear dynamic model of the vehicle. This is achieved by introducing the additional states corresponding to the relative distance between leading and following vehicles, and also the velocity of the leading vehicle. Control of the brake and throttle position is implemented by taking the state-dependent approach. The model demonstrates to be more effective in tracking the speed and distance by eliminating the necessity of switching between the two controllers. It also offers smooth variation in brake and throttle controlling signal which subsequently results in a more uniform acceleration of the vehicle. The results of proposed method are compared with other ACC systems using two separate control loops. Furthermore, an ACC simulation results using a stop&go scenario are shown, demonstrating a better fulfillment of the design requirements.     

New chatter-free sliding mode synchronization of steer-by-wire systems under chaotic conditions

Vehicle safety issues and its systems dependence on electronics are rapidly increasing. In intelligent vehicles, rigid components are replaced with controlled x-by-wire systems including configurable electronic elements. In the paper, through complete modeling of Steer-by-wire (SBW) nonlinear dynamics, the chaotic motion of the system is elucidated by a new yaw stability control method. The designed chatter free Sliding mode controller (SMC) is used to synchronize chaotic motion of the SBW system. Following stability and robustness analysis, computer simulations show that the proposed control system is quite significant for nonlinear systems like the SBW system. Besides, the robustness of the SMC against exogenous disturbance protects vehicle from undesired slide and spin motions.

     

基于路面识别的汽车ABS滑模控制方法的研究

为了提高汽车的制动效能和行驶安全性,针对目前常用的汽车ABS控制方法,在没有考虑道路状况变化对汽车滑移率及减速度等参量变化的影响而容易引起汽车侧滑、甩尾等不良状况,提出了基于路面识别的汽车ABS滑模控制方法,该方法根据制动过程中的汽车滑移率及减速度来进行路面识别,动态地获取汽车最佳滑移率,并以此对汽车ABS进行滑模控制;然后以单轮整车制动模型为对象,利用MATLAB/Simulink软件对该控制方法进行计算机仿真实验分析;结果表明,与常用的汽车ABS逻辑门限值及无路面识别的滑模控制方法相比,该方法可以使汽车制动时间减少5%～12%,从而使汽车制动效能和行驶安全性得以提高。     

Novel fuzzy feedback linearization strategy for control via differential geometry approach

The study investigates a novel fuzzy feedback linearization strategy for control. The main contributions of this study are to construct a control strategy such that the resulting closed-loop system is valid for any initial condition with almost disturbance decoupling performance, and develop the feedback linearization design for some class of nonlinear control systems. The feedback linearization control guarantees the almost disturbance decoupling performance and the uniform ultimate bounded stability of the tracking error system. Once the tracking errors are driven to touch the global final attractor with the desired radius, the fuzzy logic control is immediately applied via a human expert’s knowledge to improve the convergence rate. One example, which cannot be solved by the first paper on the almost disturbance decoupling problem, is proposed in this paper to exploit the fact that the almost disturbance decoupling and the convergence rate performances are easily achieved by the proposed approach.     

Evaluation of regenerative braking based on single-pedal control for electric vehicles

More than 25% of vehicle kinetic energy can be recycled under urban driving cycles. A single-pedal control strategy for regenerative braking is proposed to further enhance energy efficiency. Acceleration and deceleration are controlled by a single pedal, which alleviates driving intensity and prompts energy recovery. Regenerative braking is theoretically analyzed based on the construction of the single-pedal system, vehicle braking dynamics, and energy conservation law. The single-pedal control strategy is developed by considering daily driving conditions, and a single-pedal simulation model is established. Typical driving cycles are simulated to verify the effectiveness of the single-pedal control strategy. A dynamometer test is conducted to confirm the validity of the simulation model. Results show that using the single-pedal control strategy for electric vehicles can effectively improve the energy recovery rate and extend the driving range under the premise of ensuring safety while braking. The study lays a technical foundation for the optimization of regenerative braking systems and development of single-pedal control systems, which are conducive to the promotion and popularization of electric vehicles.     

Development of an Intelligent Vehicle Experiment System

Existing vehicle experiment systems tend to focus on the research of vehicle dynamics by conducting performance tests on every system or some parts of the vehicle so as to improve the entire performance of the vehicle.Virtual technology is widely utilized in various vehicle test-beds.These test-beds are mainly used to simulate the driving training,conduct the research on drivers' behaviors,or give virtual demonstrations of the transportation environment.However,the study on the active safety of the running vehicle in the virtual environment is still insufficient.A virtual scene including roads and vehicles is developed by using the software Creator and Vega,and radars and cameras are also simulated in the scene.Based on dSPACE's rapid prototyping simulation and its single board DS1103,a simulation model including vehicle control signals is set up in MATLAB/Simulink,the model is then built into C code,and the system defined file(SDF) is downloaded to the DS1103 board through the experiment debug software ControlDesk and is kept running.Programming is made by mixing Visual C++ 6.0,MATLAB API and Vega API.Control signals are read out by invoking library function MLIB/MTRACE of dSPACE.All the input,output,and system state values are acquired by arithmetic and are dynamically associated with the running status of the virtual vehicle.An intelligent vehicle experiment system is thus developed by virtue of program and integration.The system has not only the demonstration function,such as general driving,cruise control,active avoiding collision,but also the function of virtual experiment.Parameters of the system can be set according to needs,and the virtual test results can be analyzed and studied and used for the comparison with the existing models.The system reflects the running of the intelligent vehicle in the virtual traffic environment,at the same time,the system is a new attempt performed on the intelligent vehicle travel research and provides also a new research method for the development of intelligent vehicles.     

基于切入工况的自适应巡航控制系统性能测试方法研究

设计了一种基于切入工况的自适应巡航系统性能测试方法,以更好地模拟实际驾驶中前车加塞的情况,并提出了可提高自适应巡航控制系统在切入工况下的驾驶体验的有效建议.介绍了自适应巡航系统系统框架、测试设备、测试场地以及测试工况;采用控制变量法,分别以两车速度差、前车切入纵向距离和前车切入横向速度为单一变量,详细制定自适应巡航系统...     

用于扑翼飞行器气动力测试的三维力传感器研究与实验

气动力测试对验证扑翼飞行器的设计方法和优化改进飞行器重要系统特征参数起着重要的作用。 介绍了一种新研制 的结构简单、低成本、高性能的三维力传感器,用于扑翼机气动力测试系统,重点介绍了三维力传感器的设计和标定方法。 首 先,通过弹性机构的微变运动学建模验证了结构设计的可行性;然后,对传感器进行解耦标定实验,得到传感器的非线性误差小 于 1. 19% ,耦合误差小于 3. 21% ,灵敏度大于 1. 1 V/ N;最后,通过对一款小型扑翼飞行器的气动力进行测试,获得了扑翼机主 翼气动力随影响参数变化的定量评价数据,为扑翼机实现室内和室外的机动灵巧飞行,提供了有效帮助。     

基于自抗扰控制算法的两轮自平衡车分析

为解决两轮自平衡车因系统的不确定和驾驶者的不同而导致它的系统参数变化的问题,将自抗扰控制(ADRC)技术应用到两轮自平衡车的自适应控制中。该系统是以加速度计、陀螺仪为姿态传感器,与连有同轴的永磁有刷直流电机为执行机构的两轮自平衡车,考虑车轮与地面的摩擦力因素,通过物理学分析,运用牛顿力学方程建立了系统对应的非线性数学模型,得到了其状态空间方程,将系统解耦成平衡与转向两个独立的子系统,应用自抗扰控制技术估算出系统的总扰动,对系统进行了控制补偿,提出了基于自抗扰控制算法来实现两轮自平衡车的控制的方法。在Matlab中的Simulink模型/建模平台上进行了仿真评价,并通过搭建实验平台进行了不同路况的试验验证。试验结果表明:自抗扰控制技术能够满足两轮自平衡车控制的目标,可以用来控制两轮自平衡车系统。