汽车高速紧急避障路径跟踪与主动防侧翻控制

为提高匹配机械弹性车轮汽车在高速紧急避障时的效率与安全性,在Simulink中建立了整车非线性八自由度模型,并基于车轮样机台架试验数据,利用Matlab遗传算法工具箱对机械弹性车轮模型参数进行分级辨识.综合考虑行驶车速、轨迹跟踪误差、方向盘转角以及侧翻评价指标,建立了八自由度驾驶员—汽车预瞄跟随闭环系统模型.分析了汽车在不同行驶车速时所需的方向盘角输入信息与侧翻状态响应,总结出汽车高速转向时的侧翻动态特性.为高速安全通过规划的避障路径,在转向控制驾驶员模型基础上建立了速度控制驾驶员模型,当侧翻评价指标超过安全阈值时利用制动踏板降低车速,当纵向车速小于期望安全车速时利用加速踏板提高车速.仿真分析表明建立的高速避障路径跟踪与控制策略能高效完成避障路径跟踪,同时能有效降低紧急避障时的侧翻风险.     

车辆纵向速度分相控制

针对汽车纵向运动系统具有强烈非线性和参考速度输入不确定的特点,提出一种车辆纵向速度分相控制方法,可以用于车辆纵向速度闭环仿真,也可以用于智能驾驶系统纵向速度控制。算法采用分相控制思想,将车辆的纵向运动分成稳速控制相、加速控制相、急加速控制相、制动控制相、急减速控制相5个相。前3个相内采用油门控制,后2个相内采用刹车控制,在每一个相内采用抗积分饱和PID或比例控制。仿真结果表明,分相控制具有良好的速度跟随精度,并很好地解决了油门和制动的切换问题。     

Combined Control Allocation and Sliding Mode Control in the Dynamic Control of a Vehicle with Eight In-Wheel Motors

An eight wheel independently driving steering (8WIDBS) electric vehicle is studied in this paper. The vehicle is equipped with eight in-wheel motors and a steer-by-wire system. A hierarchically coordinated vehicle dynamic control (HCVDC) system, including a high-level vehicle motion controller, a control allocation, an inverse tire model and a lower-level slip/slip angle controller, is proposed for the over-actuated vehicle system. The high-level sliding mode vehicle motion controller is designed to produce desired total forces and yaw moment, distributed to longitudinal and lateral forces of each tire by an advanced control allocation method. And the slip controller is designed to use a sliding mode control method to follow the desired slip ratios by manipulating the corresponding in-wheel motor torques. Evaluation of the overall system is accomplished by sine maneuver simulation. Simulation results confirm that the proposed control system can coordinate among the redundant and constrained actuators to achieve the vehicle dynamic control task and improve the vehicle stability.     

Longitudinal Control Strategy f or Vehicle Adaptive Cruise Control Systems

A new longitudinal control strategy for vehicle adaptive cruise control (ACC) systems is presented. The running relationship between the ACC vehicle and the detected target vehicle is described by the relative velocity and the deviation between the actual headway distance and the prescribed safety distance. Based on this, two state space models are built and the linear quadratic optimal control theory is used to yield desired velocity for the ACC-equipped vehicle when with the target vehicle detected. By switching among four control modes, the desired velocity profile is designed to deal with different running situations. A velocity controller, which includes a PID controller for throttle openness and a neural network controller for brake application, is developed to achieve the desired velocity profile. The proposed control strategy is applied to a non-linear vehicle model in a simulation environment and is shown to provide the ACC vehicle comfortable ride and satisfying safety.     

基于空气悬架客车1/2模型的模糊控制仿真

为了改善空气悬架客车动态性能的控制效果,以空气悬架客车1/2 模型为控制对象,以车身垂直运动和俯仰运动加速度为控制指标,以B级路面为随机输入,应用模糊控制技术对1/2车辆模型进行了计算机控制仿真分析。结果表明:在引入垂直振动和俯仰振动2 个控制器后,车辆的行驶平顺性和操纵稳定性均得到了明显改善。     

提高车辆转向稳定性的车身主动侧倾控制研究

车辆高速转向时，车身向弯道外侧倾斜，严重时会导致侧翻事故.针对此问题，开展了提高车辆转向稳定性的车身主动侧倾控制研究.首先建立了考虑横摆和侧倾运动的六自由度车辆动力学模型；然后确定了车辆在转向运动时的期望侧倾角，并以此为控制目标设计主动侧倾控制器，使车身实际侧倾角逼近期望侧倾角.在不同行驶工况下，仿真研究了车身侧倾角、乘员感知加速度和横向载荷转移率，并考察了实现主动侧倾控制所需的主动悬架功耗和由主动侧倾引起的悬架动挠度变化.研究结果表明：主动侧倾控制能实现车辆转向时实际侧倾角迅速逼近期望侧倾角，且在复杂行驶工况下依然能使车辆具有良好的行驶稳定性；主动侧倾控制减小了悬架的动挠度峰值，使乘员感知侧向加速度和横向载荷转移率都能快速接近零值，且实现主动侧倾的主动悬架功耗较小，保证了车辆的经济性能.     

Observer-based hybrid control algorithm for semi-active suspension systems

In order to improve ride comfort and handling performance of the vehicle, an adaptive hybrid control algorithm is proposed for semi-active suspension systems. The virtues of sky-hook is combined with ground-hook control strategies and a more suitable compromise for the suspension systems is chosen. The hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high speed conditions. Damping continuous adjustable absorber is used to continuously control the damping force so as to eliminate the damping force jerk instead of traditional on-off control policy. Based on suspension stroke measured by sensors, unscented Kalman filter is designed to estimate the suspension states in real-time for the realization of hybrid control, which improves the robustness of the control strategy and is adaptive to different types of road profiles. Finally, the proposed control algorithm is validated under the following two typical road profiles: half-sine speed bump road and the random road. The simulation results indicate that the hybrid control algorithm could offer a good coordination between ride comfort and handling of the vehicle.     

静液传动高速履带车辆转向参数匹配与控制

为了解决静液传动履带车辆转向时外侧系统压力容易过高以及转向轨迹控制问题,基于双侧轮边液压驱动结构特点,提出了外侧马达采用压力、发动机转速双参数控制,内侧跟随外侧采用速度闭环控制的转向控制策略,对目标相对转向半径与方向盘转角、车速,马达排量与发动机转速、系统压力等参数进行了匹配。建立了整车转向仿真模型与实车实验系统。仿真与实验结果表明,控制策略能有效控制系统压力,参数匹配结果能满足转向控制要求,车辆按照目标相对转向半径实现了准确快速转向。     

Nonlinear Derivative and Integral Sliding Control for Tracked Vehicle Steering with Hydrostatic Drive

在静液驱动履带车辆转向过程中,车辆的运动状态总是不确定的,且阻力存在非线性、大范围的变化。因此,提高静液驱动履带车辆的转向稳定性,满足未来战场的需要具有重要意义。本文提出了一种滑模控制算法,并将其应用于保证期望横摆角速度的控制。首先通过运动学和动力学分析,建立了速度控制器和横摆角速度控制器。其次设计了非线性微分积分滑模控制算法,通过积分控制项降低积分饱和,有效地抑制不光滑路面的扰动,通过非线性微分控制项提高了系统的反应速度,减小了控制量的抖振。在RecurDyn中对静液驱动履带车辆进行建模,在控制软件MATLAB/Simulink中对转向控制策略模块进行建模。整个模型的联合仿真表明,该控制策略能够提高车辆的转向响应速度,平滑控制输出,且抖振小,具有较强的鲁棒性。     

基于模糊PID控制器的麦弗逊悬架联合仿真研究

通过实验测出磁流变阻尼器在不同电流作用下的力与速度关系的阻尼系数特征数据,并将所得阻尼数据导入麦弗逊悬架多体动力学模型;计算簧载质量速度及其变化率作为主动悬架控制的输出量;半主动悬架采用模糊PID复合控制器,用模糊控制策略对PID控制器在给定的参数范围内进行在线实时调整;在MATLAB中搭建悬架系统联合仿真模型。仿真计算结果表明:在各不同车速阶段,采用模糊PID复合控制器均对改善悬架的总体性能有明显作用;且车身垂直加速度、悬架动行程及车轮侧向滑移量在低频阶段改善突出,提升了整车在不同车速范围内的乘坐舒适性与操作稳定性。     

Fuzzy Logic Control for Semi-Active Suspension System of Tracked Vehicle

The model of half a tracked vehicle semi-active suspension is established. The fuzzy logic controller of the semi-active suspension system is constructed. The acceleration of driver‘s seat and its time derivative are used as the inputs of the fuzzy logic controller, and the fuzzy logic controller output determines the semi-active suspen-sion controllable damping force. The fuzzy logic controller is to minimize the mean square root of acceleration of the driver‘s seat. The control forces of controllable dampers behind the first road wheel are obtained by time delay, and the delay times are determined by the vehicle speed and axles distances. The simulation results show that this control method can decrease the acceleration of driver‘s seat and the suspension travel of the first road wheel,the ride quality is improved obviously.     

车辆纵向加速度自抗扰控制研究

使用自抗扰控制(ADRC)方法对车辆纵向加速度控制进行研究.首先给出以油门开度指令为控制量的发动机动态模型和车辆纵向动力学模型,对ADRC进行简要介绍;然后将模型变换为适于自抗扰控制的仿射系统,设计车辆纵向加速度ADRC控制器;最后在车辆和发动机参数摄动以及道路扰动的环境下进行仿真.结果表明,ADRC控制器能够使车辆获得快速、平稳和高精度的加速度控制效果.     

自动化公路系统车队换道变结构控制

基于车辆纵横向动力学耦合模型,研究了自动化公路系统车队换道的纵横向耦合控制.假定车队中每个跟随车辆依靠车间通信接收引导车辆以及该车前面相邻车辆的位移、速度信息,利用车载传感器获得车辆横摆角速度信息.基于满足正反梯形约束条件的侧向加速度,计算车辆换道时的期望横摆角和横摆角速度.采用有限时间滑模趋近律,设计了车队换道纵横向耦合变结构跟踪控制规律,基于李雅普诺夫稳定性理论,对控制系统的稳定性进行分析.仿真结果显示,采用文中设计的控制规律,对于车队中每个跟随车辆,在实现车辆自动换道的同时,纵向上能够保持满意的车间距离.     

Investigation on hierarchical control for driving stability and safety of intelligent HEV during car-following and lane-change process

The longitudinal and lateral coordinated control for autonomous vehicles is fundamental to achieve safe and comfortable driving performance. Aiming at this for hybrid electric vehicles (HEV) during the car-following (CF) and lane-change (LC) process while accelerating, a hierarchical control strategy for vehicle stability control is proposed. This new approach is different from the conventional hierarchical control. On the basis of model predictive control (MPC) theory, a two-layer MPC controller is designed at the top level of the control structure. The upper layer is a linear time-varying MPC (LTV-MPC), while the lower layer is a hybrid MPC (HMPC). For the LTV-MPC controller, a control-oriented linear discrete model for HEV is established, which integrates the dynamic model with three degrees of freedom (DOF) and the car-following model. The lower-layer HMPC controller is designed on the basis of the analysis for HEV hybrid characteristics and the modelling for the mixed logic dynamic (MLD) model of the HEV powertrain. As for the bottom level, a control plant including the HEV powertrain model and the 7 DOF nonlinear dynamics of the vehicle body is established. In addition, the system stability is proven. A deep fusion of vehicle dynamics control and energy management is achieved. Compared with LC-ACC control and conventional ACC control, the simulation and the hardware-in-the-loop (HIL) test results under different driving scenarios show that the proposed hierarchical control strategy can effectively maintain lateral stability and safety under severe driving conditions. Additionally, the HEV powertrain output torque and the gear-shift point are coordinated and controlled by the HMPC controller.

     

基于模糊—PID控制的对开路面汽车制动稳定性研究

提出了利用横摆力矩控制汽车在对开路面制动稳定性的方法.根据建立的动力学模型确立了相关的控制策略和控制模式,设计了参数自整定的模糊PID控制器,仿真与道路试验结果表明,利用汽车制动稳定性横摆力矩模糊-PID控制方法,能减少汽车在对开路面制动时的跑偏或激转等危险,且使汽车在制动偏驶后能快速恢复正确行驶车道,而将模糊-PID控制与模糊控制,PID控制得到的仿真结果进行对比也证明模糊-PID控制能更好的满足控制要求,从而验证了参数自整定模糊-PID控制方法对于提高汽车制动稳定性和行驶安全性的可行性.     

一种新的智能小车控制策略

传统寻迹智能小车的研究局限于设定好的路径,为了提升其自主性,提出了一种新的智能小车控制策略,融合了姿态调整算法以及避障算法,并结合模糊规则库实现了转向角与速度的协调.通过曲线拟合验证了转向角与转弯半径的关系,运用坐标变换思想大大简化了智能车位置以及圆弧切点的计算,同时,由于姿态调整算法的引入,避免了大角度转弯造成的减速运行,提高了智能车的平均速度.最后通过仿真和实验证明了算法及其控制策略的有效性.     

Implementation of MPC-Based Trajectory Tracking Considering Different Fidelity Vehicle Models

In order to investigate how model fidelity in the formulation of model predictive control(MPC) algorithm affects the path tracking performance, a bicycle model and an 8 degrees of freedom(DOF) vehicle model, as well as a 14-DOF vehicle model were employed to implement the MPC-based path tracking controller considering the constraints of input limit and output admissibility by using a lower fidelity vehicle model to control a higher fidelity vehicle model. In the MPC controller, the nonlinear vehicle model was linearized and discretized for state prediction and vehicle heading angle, lateral position and longitudinal position were chosen as objectives in the cost function. The wheel step steering and sine wave steering responses between the developed vehicle models and the Carsim model were compared for validation before implementing the model predictive path tracking control. The simulation results of trajectory tracking considering an 8-shaped curved reference path were presented and compared when the prediction model and the plant were changed. The results show that the trajectory tracking errors are small and the tracking performances of the proposed controller considering different complexity vehicle models are good in the curved road environment. Additionally, the MPC-based controller formulated with a high-fidelity model performs better than that with a low-fidelity model in the trajectory tracking.     

电动车辆ABS的改进线性二次型最优控制

为充分利用轮毂电机控制精确和响应迅速的优势,提高电动车辆制动防抱死控制的稳定性,提出一种用于轮毂电机电动车辆制动防抱死系统(ABS)协调控制的改进线性二次型最优控制方法.建立电动车辆纵向动力学模型;结合复合制动系统的协调控制策略,分析现有线性二次型最优控制算法无法用于防抱死控制器设计的原因,提出一种通过构造虚拟阻尼量以及无穷小量来建立黎卡提方程的改进型线性二次型最优控制算法,并据此设计了防抱死控制器.在高附着路面、中附着路面和低附着路面3种不同行驶工况,对分别安装有改进线性二次型最优防抱死控制器和滑模防抱死控制器的电动车辆的紧急制动性能进行了仿真分析.结果表明:在不同附着系数路面行驶工况下,改进线性二次型最优控制算法能够有效提高电动汽车防抱死控制系统的控制精度和响应速度.     

基于线性矩阵不等式的智能车轨迹跟踪控制

针对传统的基于精确数学模型的智能车轨迹跟踪控制器跟踪精度低,鲁棒性弱,很难适应复杂多变的驾驶环境等问题,结合线性矩阵不等式(LMI)鲁棒控制具有易于求解、抗干扰能力强等优点,提出基于LMI的智能车轨迹跟踪控制方法. 将车辆侧向动力学状态空间模型进行坐标变换,得到基于跟踪误差的车辆侧向动力学状态空间模型,采用饱和线性轮胎得到车辆侧向动力学多胞型模型;设计LMI反馈控制器,在控制器中引入前馈控制量,以消除侧向位置稳态误差. Carsim和Matlab/Simulink的联合仿真表明,该控制器在保证车辆稳定性的基础上具有较高的跟踪精度,对车速和路面附着系数具有较强的鲁棒性. 与模型预测控制器(MPC)和预瞄驾驶员模型(PDM)控制器进行对比,结果表明,设计的该控制器轨迹跟踪精度更优.     

高速无人驾驶车辆轨迹跟踪和稳定性控制

针对高速无人驾驶车辆运动控制过程中轨迹跟踪精度和稳定性难以同时保障的问题,提出综合前馈-反馈及自抗扰控制(ADRC)补偿相结合的横向控制算法. 通过车速和道路曲率信息计算前馈稳态前轮转向角,将质心侧偏角引入航向偏差,以车辆航向角偏差和侧向偏差作为参考量进行反馈控制,通过前馈-反馈控制提升瞬态轨迹跟踪性能. 设计自抗扰控制器,通过扩张状态观测器对未建模动态和内外界干扰进行估计,通过将后轮侧偏角控制在参考值附近来补偿前轮转角,提升无人驾驶车辆的转向稳定性和控制器的鲁棒性. 不同工况下的仿真结果表明,利用该方法可以保证高速无人驾驶车辆稳定地跟踪期望路径行驶,轨迹跟踪偏差较小,对车辆参数变化和外界干扰具有较强的鲁棒性.