组合阀旁通流量式ECHPS控制器设计与试验

提出了一种组合阀式旁通流量控制的电控液压助力转向系统(ECHPS),该ECHPS具有随车速变化的可变助力特性。设计了ECHPS控制器,运用Multisim软件对控制器硬件电路进行了仿真分析,最后通过台架试验对控制器及ECHPS性能进行了测试。结果表明,控制器性能稳定可靠,ECHPS助力特性随车速变化明显,既保证了重型商用车的低速转向轻便性,又改善了中高速行驶时的转向盘路感,提高了车辆的操纵稳定性和行驶安全性。     

电动助力转向系统组合型助力特性研究

建立了装有EPS的整车转向动力学模型,以某微型轿车管柱式EPS为例,对常见的直线型、折线型和曲线型助力特性进行了对比分析.根据直线型和曲线型助力特性在转向轻便性和路感方面的互补性,设计了一种新的组合型助力特性.实车仿真结果表明,所设计的组合型助力特性在路感方面优于直线型和折线型,在转向轻便性方面优于曲线型,能较好地协调不同车速时的转向轻便性和路感要求.     

基于整车多自由度的电动助力转向系统建模与仿真

在电动助力转向系统（EPS）的数学模型和整车八自由度模型基础上,建立了基于Matlab／Simulink的电动助力转向系统仿真模型。基于扭矩输入对电动助力转向系统应用PID进行助力控制。仿真结果表明,所设计的电动助力转向系统在改善转向轻便型和路感的同时,具有很好的抗干扰性能,能提高汽车行驶的操纵稳定性和安全性。     

电动轮汽车差速助力转向路感分析

电动轮汽车为汽车转向技术提供了一种新的方法,它运用了差速助力转向系统,在可以实现转向灵敏和转向路感的完美结合的同时,有效降低了汽车转向系统的能耗,解决了转向系统机械结构复杂的问题,提高了汽车行驶的安全性,是一种比较理想的汽车动力转向技术。文中采用拉格朗日方法建立考虑车身侧倾的3自由度汽车转向系统模型,并对差动助力转向系统进行转向路感分析,通过在Matlab中建立模型进行仿真,研究各个参数对路感的影响,得出了影响路感的参数。     

电子控制速度传感型动力转向

随着动力转向在汽上的日益普及,对其性能的要求已不再是单纯地为了减轻操作强度,而是能根据车速与行驶条件的不同而产生相应的、合适的转向力。理想的动力系统应在车桥停车状态时能提供足够的助力,使原地转向容易,即随着车速的增加助力逐渐减少,当高速行驶时则无助力但仍保有普通的“路感”。为此要求只能采用可变助力的液压动力转向系统。例如     

电动助力转向系统助力特性研究

概述了电动助力转向系统(EPS)的结构和工作原理,并介绍了电动助力转向系统助力特性的设计方法。在分析了电动助力转向系统各组成部分数学模型的基础上,构建了基于Simulink与carsim的电动助力转向系统仿真模型,仿真结果表明:所设计的助力特性较好地协调了转向轻便性和路感之间的矛盾。     

汽车可变转向系统结构及工作原理

现在,普通轿车都带有转向助力系统。转向助力系统可以大大减轻驾驶者的疲劳强度,但是也有一点副作用,那就是汽车高速行驶时由路面通过轮胎反馈到方向盘的路感降低了,高速时方向盘太轻造成方向稳定性变差。所以有了可变助力转向原理,就是在车速高时减少助力方向盘变重增加稳定性,低速时增加助力方向盘变轻减轻疲劳强度。     

电动助力转向助力特性的仿真分析

首先利用ADAMS软件建立分析电动助力转向系统的整车动力学仿真模型,然后系统分析助力特性曲线的特征型式对转向轻便性和路感的影响。这种研究方法能缩短产品的开发周期和节约试验经费。     

线控转向系统路感模糊控制仿真分析

驾驶员希望通过转向盘的力矩信息感知汽车的行驶状态。文章主要研究汽车转向盘力特性与转向盘转角、车速、侧向加速度及转向阻力矩的关系,运用多变量模糊控制技术研究了线控转向系统的路感,通过ADAMS提供离线汽车数据,在Matlab／Simulink中对路感多变量模糊控制器进行了仿真,并对其中一种控制结构进行了硬件在环试验,给出了路感多变量模糊控制的一种参数调整方法以及路感数据。表明仿真同硬件在环仿真结果基本一致,验证了路感多变量模糊控制方法可行。     

电动助力转向系统助力特性的仿真分析

首先利用ADAMS软件建立了分析电动助力转向系统的整车动力学仿真模型,然后系统分析了助力特性曲线的特征形式对转向轻便性和路感的影响。这种研究方法能缩短产品的开发周期、节约试验经费。     

电动转向系统特性分析

建立了电动转向系统的动态模型,应用控制理论,分析了该系统动态特性中的助力特性、随从特性、转向路感以及系统稳定所需的条件,讨论了主要参数的变化对其产生的影响。动态特性分析及参数讨论对该系统的工程设计有一定的指导意义。     

A model of driver steering control incorporating the driver's sensing of steering torque

Steering feel, or steering torque feedback, is widely regarded as an important aspect of the handling quality of a vehicle. Despite this, there is little theoretical understanding of its role. This paper describes an initial attempt to model the role of steering torque feedback arising from lateral tyre forces. The path-following control of a nonlinear vehicle model is implemented using a time-varying model predictive controller. A series of Kalman filters are used to represent the driver's ability to generate estimates of the system states from noisy sensory measurements, including the steering torque. It is found that under constant road friction conditions, the steering torque feedback reduces path-following errors provided the friction is sufficiently high to prevent frequent saturation of the tyres. When the driver model is extended to allow identification of, and adaptation to, a varying friction condition, it is found that the steering torque assists in the accurate identification of the friction condition. The simulation results give insight into the role of steering torque feedback arising from lateral tyre forces. The paper concludes with recommendations for further work.     

Objectification of steering feel around straight-line driving for vehicle/tyre design

This paper presents the objectification techniques for the assessment of steering feel including {on-centre} feel and steering response by measurement data. Here, new objective parameters are developed by considering not only the process by which the steering feel is evaluated subjectively but also by the ergonomic perceptive sensitivity of the driver. In order to validate such objective parameters, subjective tests are carried out by professional drivers. Objective measurements are also performed for several cars at a proving ground. The linear correlation coefficients between the subjective ratings and the objective parameters are calculated. As one of new objective parameters, steering wheel angle defined by ergonomic perception sensitivity shows high correlation with the subjective questionnaires of on-center responses. Newly defined steering torque curvature also shows high correlation with the subjective questionnaires of on-center effort. These correlation results conclude that the subjective assessment of steering feel can be successfully explained and objectified by means of the suggested objective parameters.     

Interaction of vehicle and steering system regarding on-centre handling

For the on-centre handling behaviour of vehicles the steering system is absolutely important. To investigate the interaction of the vehicle and steering system a validated, especially tailored simulation model was developed. Some meaningful vehicle and steering system parameters are altered to show the influence on steering wheel torque, steering feel and understeer. The results underline the importance of an accurate steering system model. Identified measures to improve the centre feel and steering response were a stiffer torsion bar, a higher cornering stiffness or a lower overall steering ratio. The steering response, however, suffers when the centre feel is improved by a higher trail. The steering rack friction reduces mainly the steering response while the steering column friction decreases the centre feel whereas a stiffer torsion bar lessens the understeer tendency.     

Interaction of vehicle and steering system regarding on-centre handling

For the on-centre handling behaviour of vehicles the steering system is absolutely important. To investigate the interaction of the vehicle and steering system a validated, especially tailored simulation model was developed. Some meaningful vehicle and steering system parameters are altered to show the influence on steering wheel torque, steering feel and understeer. The results underline the importance of an accurate steering system model. Identified measures to improve the centre feel and steering response were a stiffer torsion bar, a higher cornering stiffness or a lower overall steering ratio. The steering response, however, suffers when the centre feel is improved by a higher trail. The steering rack friction reduces mainly the steering response while the steering column friction decreases the centre feel whereas a stiffer torsion bar lessens the understeer tendency.     

Influencing driver chosen cornering speed by means of modified steering feel

This paper presents an investigation about influencing the driver's behaviour intuitively by means of modified steering feel. For a rollover indication through haptic feedback a model was developed and tested that returned a warning to the driver about too high vehicle speed. This was realised by modifying the experienced steering wheel torque as a function of the lateral acceleration. The hypothesis for this work was that drivers of heavy vehicles will perform with more margin of safety to the rollover threshold if the steering feel is altered by means of decreased or additionally increased steering wheel torque at high lateral acceleration. Therefore, the model was implemented in a test truck with active steering with torque overlay and used for a track test. Thirty-three drivers took part in the investigation that showed, depending on the parameter setting, a significant decrease of lateral acceleration while cornering.     

Research on control strategy for differential steering system based on H mixed sensitivity

The differential steering system (DSS) of electric wheel vehicle gets rid of the restrictions of traditional steering system completely. As an ideal steering technology, it not only realizes the perfect combination of the road feel and the steering portability, but also realizes the harmony and unification between the steering maneuverability and safety. The structure and basic theory of the DSS of electric wheel vehicle are discussed in this paper. Based on these, the dynamic model of the steering system is built. Considering of the uncertainties and disturbances existing in the model, the H_∞ mixed sensitivity control theory is applied to achieve better tracking performance and road feel in the process of steering. Then, a H_∞ mixed sensitivity controller is designed to restrain the effect of the road disturbance and model uncertainties. The simulation results indicate that the DSS with the designed controller can effectively restrain the effect of noises and disturbances caused by random motivation from road, torque sensor measurement and model parameter uncertainty, and enable the driver to obtain satisfactory road feel.