汽车防抱死制动系统的H_∞鲁棒控制

为克服道路条件变化与汽车载质量、制动器效能因数和胎压等参数摄动及因忽略系统非线性因素而出现的未建模动态特性给汽车制动防抱死系统(ABS)控制带来的不良影响,提高其鲁棒性和控制精度,运用汽车动力学理论,建立了ABS系统的数学模型并进行了适当简化。采用混合灵敏度方法设计了基于滑移率控制的ABS系统H∞鲁棒控制器。利用Matlab/Simulink对所设计的鲁棒控制系统进行了仿真,并与传统PID控制作了对比分析。结果表明,ABS鲁棒控制器在控制精度、鲁棒稳定性及响应时间等方面都优于传统PID控制;在汽车载质量、制动效能因数和道路条件等发生变化的情况下,ABS鲁棒控制器均能承受参数变化的不确定性,并将车轮滑移率有效地控制在期望值附近,明显提高了整车的制动性能。     

汽车防抱死制动系统H_∞控制与PID控制的比较研究

控制方法是汽车防抱死制动系统的核心技术。为了提高ABS系统的鲁棒性能,在建立汽车防抱死制动系统数学模型的基础上,设计了H∞控制器,在Matlab/Simulink平台上对基于H∞控制器的ABS系统进行了动态仿真,并与基于传统PID控制器的ABS系统进行对比。通过对仿真结果进行比较发现,PID控制和H∞控制都能使ABS系统获得较好的制动性能;H∞控制响应迅速、具有优秀的稳定性和鲁棒性,总体控制效果优于PID控制。     

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。     

基于模型匹配方法的汽车主动避撞下位控制系统

针对汽车主动避撞系统下位控制的鲁棒性要求，应用模型匹配控制理论，设计了汽车主动避撞下位系统的控材器；并解决了下位控制系统鲁棒稳定性和鲁棒跟随性难以得到兼顾的问题；通过实车试验结果对此控制器性能进行了验证；获得了较好的效果。     

主动转向系统的神经网络模型逼近自适应控制的研究

将主动转向系统模型与2自由度整车模型相结合,组成被控对象模型。为提高具有非线性特性和不确定性的主动转向系统的自适应性能和鲁棒性能,采用基于线性RBF神经网络的模型逼近自适应控制方法,以横摆率和以横摆率与侧偏角变化率相组合为被控对象参数分别设计C1和C2两种自适应控制器,并对它们进行鲁棒性和稳定性分析。采用1阶参考模型和指令滤波器,对两种自适应控制器和考虑不确定性的H∞鲁棒控制器进行了多种非线性对比仿真。结果表明,自适应控制器比H∞鲁棒控制器有更好的动态和静态跟随性能;而两种自适应控制器中,C2控制器又略胜一筹。     

无人驾驶车辆侧向鲁棒控制的研究

介绍了车辆模型，提出了一种侧向鲁棒控制器的设计方法，给出了道路曲率的平滑算法及闭环系统的仿真结果，并进行了跟踪误差分析。各种工况下的仿真结果表明，该方法设计的鲁棒控制系统能够同时满足精确道路跟踪、良好的舒适性以及抗多种干扰的鲁棒性等多项性能要求。     

摩托车用机械式ABS功能分析与性能测试

为提高中、低档摩托车的制动安全性能，根据摩托车防抱制动系统（Anti-Lock Brake System，简称ABS）的功能原理，设计出能有效地控制制动压力迅速上升的机械式防抱死控制器，对该控制器进行高、中、低三种路面状况输入输出端制动压力的静态和动态试验以及实际路况试验，取得了预期效果。目前该控制器已投入小批量生产。     

车辆电动悬架的混合不确定建模与μ综合控制器设计

考虑悬架和电机作动器的参数摄动和控制输入的高阶未建模不确定性,利用线性分式变换理论对已开发的车辆电动悬架系统进行混合不确定建模和仿真,并设计了μ综合控制器.仿真得到了主动悬架和被动悬架的频率和时间响应.结果表明,相比被动悬架,所设计的μ综合控制器对乘坐舒适性有很大的提升.μ分析表明,与基于主动悬架名义模型设计的H∞综合控制器相比,μ综合控制器可使闭环系统获得更好的鲁棒稳定性和鲁棒性能.     

摇臂推杆式电磁主动悬架的鲁棒控制与优化

针对被动悬架和半主动悬架在抑制车辆振动方面存在的不足,提出一种摇臂推杆式电磁主动悬架并试制样机,它具有结构新颖、加工容易和模块化设计等特点。对该悬架系统非线性特性进行分析,得到等效刚度和等效簧下质量等参数的摄动区间。在保证系统鲁棒稳定性的前提下,以车身加速度、悬架动行程、轮胎动位移和主动力最小作为优化目标,设计鲁棒H∞控制器。为降低控制器保守性,将车身质量参数摄动范围分段,优化设计自适应鲁棒H∞控制器,通过静态查表方式离线控制,保证实时性,且无需切换控制器,避免对乘员产生的冲击感。     

基于鲁棒反馈控制理论的路径跟踪控制器设计

为了提高智能车辆路径跟踪的精确性和鲁棒性，基于李雅普诺夫稳定性（Lyapunov Stability）理论设计了鲁棒反馈路径跟踪控制器，运用舒尔（Schur）补引理并求解线性矩阵不等式（LMI）得到控制系统的反馈矩阵。通过搭建CarSim/Simulink联合仿真平台将鲁棒反馈控制器与线性二次型调节器（LQR）进行对比分析，以不同的车速分别在不同附着系数的路面上进行仿真，验证所设计控制器的性能。仿真结果表明：在不同路面和车速工况下，相较于LQR控制器，基于李雅普诺夫稳定性理论的鲁棒反馈控制器具有更高的控制精度，同时具有更强的鲁棒性。     

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.     

Handling stability improvement through robust active front steering and active differential control

The design of the integrated active front steering and active differential control for handling improvement of road vehicles is undertaken. The controller design algorithm is based on the solution of a set of linear matrix inequalities that guarantee robustness against a number of vehicle parameters such as speed, cornering and braking stiffnesses. Vehicle plane dynamics are first expressed in the generic linear parameter-varying form, where the above-stated parameters are treated as interval uncertainties. Then, static-state feedback controllers ensuring robust performance against changing road conditions are designed. In a first series of simulations, the performance of the integrated controller is evaluated for a fishhook manoeuvre for different values of road adhesion coefficient. Then, the controller is tested for an emergency braking manoeuvre executed on a split-μ road. In all cases, it is shown that static-state feedback controllers designed by the proposed method can achieve remarkable road handling performance compared with uncontrolled vehicles.     

基于视觉识别的线控制动压力滑模控制

制动安全是车辆主动安全的关键技术之一。制动决策和执行器控制是影响线控制动系统性能的两个主要因素。路面自适应性和控制器鲁棒性分别对制动决策和执行器控制有着重要影响,制约着线控制动系统的发展。本文中以一种液压调控的线控制动系统为基础,针对路面自适应性和控制器鲁棒性问题,提出一种双层结构的制动系统控制器,上层采用计算机视觉的方法对路面类型进行识别,根据识别结果制定当前路面的最佳滑移率;下层针对制动系统参数不确定性问题,引入滑模控制理论对制动过程中的最佳滑移率进行跟踪控制。通过仿真与实验验证,结果表明,双层结构的制动系统控制器相比传统控制器,路面的自适应性好,制动距离更短,控制器鲁棒性好。     

Improvement of drivability and fuel economy with a hybrid antiskid braking system in hybrid electric vehicles

When braking on wet roads, Antilock Braking System (ABS) control can be triggered because the available brake torque is not sufficient. When the ABS system is active, for a hybrid electric vehicle, the regenerative brake is switched off to safeguard the normal ABS function. When the ABS control is terminated, it would be favorable to reactivate the regenerative brake. However, recurring cycles from ABS to motor regenerative braking could occur. This condition is felt to be unpleasant by the driver and has adverse effects on driving stability. In this paper, a novel hybrid antiskid braking system using fuzzy logic is proposed for a hybrid electric vehicle that has a regenerative braking system operatively connected to an electric traction motor and a separate hydraulic braking system. This control strategy and the method for coordination between regenerative and hydraulic braking are developed. The motor regenerative braking controller is designed. Control of regenerative and hydraulic braking force distribution is investigated. The simulation and experimental results show that vehicle braking performance and fuel economy can be improved and the proposed control strategy and method are effective and robust.     

Fault-tolerant braking control with integerated EMBs and regenerative in-wheel motors

This paper presents a fault-tolerant brake torque controller for four-wheel-distributed braking systems with in-wheel motors and Electro-Mechanical Brakes (EMB). Mechanical and electrical faults can degrade the performance of the EMB actuators and, thus, their effects need to be compensated in vehicle dynamics level. In this study, the faults are identified as performance degradation and expressed by the gains of each actuator. Assuming the brake force distribution and the regenerative braking ratios, the over-actuated braking system is simplified into a two-input system. A sliding mode controller is designed to track the driver’s braking and steering commands, even if there exist faults in EMBs. In addition, adaptive schemes are constructed to achieve the fault-tolerant control in braking. The proposed controller and strategies are verified in the EMB HILS (Hardware-in-loop-simulation) unit for various conditions.     

Robust control of anti-lock brake system

A robust control algorithm for an anti-lock brake system is proposed. The method used is based on static-state feedback of longitudinal slip and does not involve controller scheduling with changing vehicle speed or road adhesion coefficient estimation. An improvement involving scheduling of longitudinal slip reference with longitudinal acceleration measurement is included. Electromechanical braking actuators are used in simulations, and the algorithm used in this study is shown to have high performance on roads with constant and varying adhesion coefficients, displaying nice robustness properties against large vehicle speed and road adhesion coefficient variations. Guidelines are provided for tuning controller gains to cope with unknown actuator delay and measurement noise.     

Combined emergency braking and turning of articulated heavy vehicles

‘Slip control’ braking has been shown to reduce the emergency stopping distance of an experimental heavy goods vehicle by up to 19%, compared to conventional electronic/anti-lock braking systems (EBS). However, little regard has been given to the impact of slip control braking on the vehicle’s directional dynamics. This paper uses validated computer models to show that slip control could severely degrade directional performance during emergency braking. A modified slip control strategy, ‘attenuated slip demand’ (ASD) control, is proposed in order to rectify this. Results from simulations of vehicle performance are presented for combined braking and cornering manoeuvres with EBS and slip control braking with and without ASD control. The ASD controller enables slip control braking to provide directional performance comparable with conventional EBS while maintaining a substantial stopping distance advantage. The controller is easily tuned to work across a wide range of different operating conditions.     

Design of a hydraulic anti-lock braking modulator and an intelligent brake pressure controller for a light motorcycle

The object of this paper is to design a new hydraulic modulator and an intelligent sliding mode pulse width modulation (PWM) brake pressure controller for an anti-lock braking system, for application to light motorcycles. The paper presents a design principle and a mathematical analysis of the hydraulic anti-lock braking modulator. The intelligent sliding mode PWM brake pressure controller based on vehicle acceleration is designed and tested. A three-phase pavement experiment and a rear brake influence test are undertaken to verify the performance of the controller and the modulator. A light motorcycle is built for the real vehicle anti-lock braking experiments. The experimental results show that both the intelligent controller and the hydraulic modulator designed in the study perform well in the anti-lock braking operation.     

A practical identifier design of road variations for anti-lock brake system

Emergency brake technologies have always been a major interest of vehicle active safety-related studies. On homogeneous surfaces, traditional anti-lock brake system (ABS) can achieve efficient braking performance and maintain the handling capability as well. However, when road conditions are time variant during the braking process, or different at the bilateral wheels, braking stability performance is likely to be degraded. To address this problem and enhance ABS performances, a practical identifier of road variations is developed in this study. The proposed identifier adopts a statechart-based approach and is hierarchically constructed with a wheel layer and a full vehicle layer identifier. Based on the identification results, modifications are made to a four-phase wheel-behaviour-based ABS controller to enhance its performance. The feasibility and effectiveness of the proposed identifier in collaborating with the modified ABS controller are examined via simulations and further validated by track tests under various practical braking scenarios.     

基于模糊解耦控制的车辆转向制动系统研究

车辆转向系统和制动系统之间存在着很强的速度耦合关系,造成两个系统之间的性能相互影响,使得车辆在转向制动这一工况成了汽车最危险的工况之一。本文结合实际车辆参数建立转向系统的二自由度模型和制动系统的单车轮模型,针对车辆转向制动工况设计了模糊解耦控制器,实现了车辆的转向与制动同时控制。经验证含有模糊解耦控制的车辆转向制动系统具有很好的动态控制效果,并且有很强的鲁棒性和自适应性。