基于ITS的汽车主动避撞性关键技术研究(二)

3.2.3 下位控制方法研究 由于车辆制动、驱动力特性中含有强烈非线性,同时车辆质量变动、道路坡度及风阻等外部干扰因素的存在,车辆下位控制器设计时如果不采用模型匹配控制方法,则控制系统的鲁棒跟随性和鲁棒稳定性必然是相互对立的两个性能。针对这一问题,本研究设计了二自由度控制器来实现车辆主动避撞系统下位控制的控制性能,此控制器的特征是闭环目标值应答特性可以通过反馈特性的设计来独立设定。在这种情况下,利用前馈补偿器来设定目标值的应答特性(本研究中是模型匹配特性),利用反馈补偿器的设计来实现反馈特性(本研究中是鲁棒跟随特性和鲁棒稳定特性),很好地实现了控制要求。 为了进行控制系统补偿器的设计,必须求出控制对象的标准传递函数。在本研究中,从控制对象的频率特性出发,利用响应特性的相似性来求得控制对象的传递函数。     

汽车主动避撞系统关键技术研究

介绍了汽车主动避撞系统的研究情况，主要包括：汽车主动避撞的技术思路、系统结构及关键技术。对该技术在我国的实用化研究提出了建议。     

汽车主动避撞系统中的报警方法及其关键技术

在分析现代汽车主动避撞系统特性的基础上设计了汽车主动避撞报警系统，对系统报警方法，雷达信号的Kalman滤波处理，雷达目标物有效性识别算法等关键技术进行了研究，给出了系统合理性及实用性验证的仿真及初步试验结果。     

基于ITS的汽车主动避撞性关键技术研究(一)

利用信息感知、动态辨识、控制等技术与方法提高汽车的主动安全性，是智能交通系统（ITS）的主要研发内容之一。介绍了基于ITS的汽车主动避撞关键技术的研究工作，主要包括：车辆运动中对周围障碍物的感知技术方法；危险或安全状态的动态辨识；具有主动避撞性能的ACC（Adaptive Cruise Control）技术等；给出了相关技术研究的仿真及实验结果，并对该技术在我国的实用化前景进行了展望。     

汽车主动悬架鲁棒保性能控制仿真研究

针对具有控制量和输出硬约束的不确定系统,研究了一种鲁棒保性能控制方法,将汽车主动悬架的控制问题视为有时域硬约束的鲁棒干扰抑制问题。将车身加速度作为系统的H2最小化输出性能指标,悬架动行程和轮胎动载荷作为H∞性能指标,得到系统的鲁棒H2/H∞最优保性能控制律。通过实例的仿真验证了鲁棒保性能控制方法的有效性和可行性,改善了带主动悬架系统汽车的乘坐舒适性。     

汽车主动避撞系统的发展现状及趋势

阐述了汽车主动避撞系统的实现思路和结构,重点介绍了状态识别、安全状态判断、系统控制理论方法等关键技术,指出了汽车主动避撞系统研究中存在的一些问题及发展趋势.     

智能网联汽车主动避撞系统发展综述

针对当前典型的主动避撞系统及技术发展进行了全面综述，介绍了主动避撞系统的分类及其技术原理，归纳主动避撞系统的核心关键技术研究现状及技术水平，并对已量产的主动避撞产品进行了总结，最后，对主动避撞系统的发展趋势进行了分析与预测。     

基于驾驶员特性的主动避撞分级制动策略与验证

为准确而直观地判断当前工况的危险程度,充分利用已知的车间运动信息,以安全时距模型为基础,提出了一种新的碰撞时间(TTC)的建模方法。基于危险判定指标TTC开发了一种符合驾驶员避撞特性的主动避撞系统;设计了主动避撞分级制动策略,其关键参数根据驾驶员特性和实车试验结果确定;同时,引入了一个预警门限值T_w,设计了采用声、光预警的主动避撞预警策略,帮助驾驶员实现有效避撞。实车试验结果表明:该系统的分级制动和预警策略符合驾驶员的避撞特性,体现了驾驶员控制的优先性和协调性,可有效避免碰撞,满足汽车主动避撞的要求。     

新型汽车主动避撞安全距离模型

针对现有模型的不足，以驾驶员车间距保持目的假设为基础建立了一种新型汽车主动避撞安全距离模型，通过驾驶员试验获得了反映驾驶员驾驶特点的模型参数。经仿真及试验对比，该模型计算结果体现了驾驶员的驾驶特点，能够适用于多种交通状况，满足了汽车主动避撞系统的要求。     

基于等效力的汽车主动避撞模型及其仿真

为使汽车主动避撞模型能够在人-车-路不同行车环境下保证汽车的主动避撞效果,建立了基于等效力的汽车主动避撞模型.通过以汽车风险评估中提出的等效力模型为基础,加入路面附着系数因子、驾驶员激进程度因子和汽车速度因子,得到行车等效力模型,通过实际行车等效力与不同行车环境中的标准等效力进行对比,实现汽车主动避撞预警.利用Simu...     

Decoupled robust control of vehicular platoon with identical controller and rigid information flow

Platoon driving has potential to significantly benefit road traffic. This study presents a decoupled robust control strategy for a vehicular platoon with identical feedback controller and rigid information topology. The node dynamics of vehicle with a lower-level controller is assumed to be covered by a multiplicative uncertainty model. The vehicular platoon control system is skillfully decomposed into an uncertain part and a diagonal system by applying linear transformation and eigenvalue decomposition on information flow graph. Then the requirements of robust stability and distance tracking error are equivalent to the H-infinity norm of decoupled sub-systems. Comparative simulations with a non-robust controller and different communication topologies are conducted to demonstrate the robust stability and distance tracking performances of the proposed method.     

Robust yaw stability control for electric vehicles based on active front steering control through a steer-by-wire system

A robust yaw stability control design based on active front steering control is proposed for in-wheel-motored electric vehicles with a Steer-by-Wire (SbW) system. The proposed control system consists of an inner-loop controller (referred to in this paper as the steering angle-disturbance observer (SA-DOB), which rejects an input steering disturbance by feeding a compensation steering angle) and an outer-loop tracking controller (i.e., a PI-type tracking controller) to achieve control performance and stability. Because the model uncertainties, which include unmodeled high frequency dynamics and parameter variations, occur in a wide range of driving situations, a robust control design method is applied to the control system to simultaneously guarantee robust stability and robust performance of the control system. The proposed control algorithm was implemented in a CaSim model, which was designed to describe actual in-wheel-motored electric vehicles. The control performances of the proposed yaw stability control system are verified through computer simulations and experimental results using an experimental electric vehicle.     

汽车纵向加/减速度多模型分层切换控制

针对汽车纵向动力学模型的大不确定性,设计了一种基于鲁棒控制理论的汽车纵向加速度多模型分层切换控制系统。通过分析汽车纵向动力学特性,用4个不确定模型覆盖对象不确定性,并应用LM I方法设计对应的鲁棒性能控制器集合。考虑鲁棒控制系统的特点,设计了一种对不确定性的系统增益进行估计的切换指标函数,以选择控制器进行控制。实验表明,提出的方法在大不确定性下可以对纵向加速度有效控制。     

车辆防抱系统鲁棒控制的研究

本文讨论了防抱制动系统鲁棒控制器设计问题，采用鲁棒和性能加权，系统有效地抗干扰和参数变化，使控制器有效地适应不同的路况及制动工况，与ＰＩＤ算法进行了比较，模拟的结果证实了该控制器的优良品质。     

Design and Evaluation of Robust Cooperative Adaptive Cruise Control Systems in Parameter Space

This paper is on the design of cooperative adaptive cruise control systems for automated driving of platoons of vehicles in the longitudinal direction. Longitudinal models of vehicles with simple dynamics, an uncertain first order time constant and vehicle to vehicle communication with a communication delay are used in the vehicle modeling. A robust parameter space approach is developed and applied to the design of the cooperative adaptive cruise control system. D-stability is chosen as the robust performance goal and the feedback PD controller is designed in controller parameter space to achieve this D-stability goal for a range of possible longitudinal dynamics time constants and different values of time gap. Preceding vehicle acceleration is sent to the ego vehicle using vehicle to vehicle communication and a feedforward controller is used in this inter-vehicle loop to improve performance. Simulation results of an eight vehicle platoon of heterogeneous vehicles are presented and evaluated to demonstrate the efficiency of the proposed design method. Also, the proposed method is compared with a benchmark controller and the feedback only controller. Time gap regulation and string stability are used to assess performance and the effect of the vehicle to vehicle communication frequency on control system performance is also investigated.     

Design of rollover prevention controller with linear matrix inequality-based trajectory sensitivity minimisation

This paper presents a method to design a rollover prevention controller for vehicle systems. The vehicle rollover can be prevented by a controller that minimises the lateral acceleration and the roll angle. Rollover prevention capability can be enhanced if the controlled vehicle system is robust to the variation of the height of the centre of gravity and the speed of the vehicle. For this purpose, a robust controller is designed with linear matrix inequality-based trajectory sensitivity minimisation. Differential braking and active suspension are adopted as actuators that generate yaw and roll moments, respectively. The newly proposed method is shown to be effective in preventing rollover by the simulation on a non-linear multibody dynamic simulation software, CarSim^®.     

Robust control for four-wheel-independent-steering electric vehicle with steer-by-wire system

A four-wheel-independent-steering (4WIS) electric vehicle (EV) with steer-by-wire (SBW) system is proposed in this paper. The fast terminal sliding mode controller (FTSMC) is designed for the SBW system to suppress external disturbances. Taking unstructured and structured uncertainties into consideration, a robust controller is designed for the 4WIS EV utilizing μ synthesis approach and the controller order reduction is implemented based on Hankel-Norm approximation. Since sideslip angle is the feedback signal of robust controller and it is hard to measure, the extended Kalman filter (EKF) is employed to estimate sideslip angle. To evaluate the vehicle performance with the designed control system, step and sinusoidal steering maneuvers are simulated and analyzed. Simulation results show that the designed control system have good tracking ability, strong robust stability and good robust performance to improve vehicle stability and handing performance.     

越野车辆差速器同步锁止机构自动控制系统模糊控制方法研究

本文采用模糊控制方法对差速器同步锁止机构自动控制系统进行了研究。建立了车辆模糊控制模型，并进行了模拟实验。模拟实验结果表明：基于模糊控制的差速器同步锁止机构自动控制系统鲁棒性强，控制效果好，系统的移植性好。     

Robust control for 4WS vehicles considering a varying tire-road friction coefficient

A µ-synthesis for four-wheel steering (4WS) problems is proposed. Applying this method, model uncertainties can be taken into consideration, and a µ-synthesis robust controller is designed with optimized weighting functions to attenuate the external disturbances. In addition, an optimal controller is designed using the well-known optimal control theory. Two different versions of control laws are considered here. In evaluations of vehicle performance with the robust controller, the proposed controller performs adequately with different maneuvers (i.e., J-turn and Fishhook) and on different road conditions (i.e., icy, wet, and dry). The numerical simulation shows that the designed µ-synthesis robust controller can improve the performance of a closed-loop 4WS vehicle, and this controller has good maneuverability, sufficiently robust stability, and good performance robustness against serious disturbances.     

New energy recovery H∞ robust controller for electric bicycles

The electric controller is one of the most crucial components in an electric bicycle. The overall performance of the whole system heavily depends on the properties of the controller. The authors use the robust control theory to design a new H_∞ robust controller for the closed speed-current dual-loop driving and braking system. The designed controller also incorporates the driving and energy recovery braking circuit. Therefore, it has energy recovery ability, which coverts the kinetic energy wasted in braking into electric energy to recharge the battery. This prolongs the driving distance per battery charge. The simulations and experiments show that the new H_∞ robust controller out-performs the traditional PID controller in many respects including stability, error, responding speed and driving distance per battery charge.