线控转向系统转向盘力回馈控制模型的研究

根据轮胎和传统转向系的力学特性提出了利用车轮转角和车速计算得到转向盘回馈力的思路,并以此建立了线控转向系统转向盘回馈力控制模型,仿真和试验表明该模型能够满足路感要求。     

电动助力转向系统的回正与主动阻尼控制策略研究

针对配备电动助力转向系统的车辆低速时回正性差,而中高速时又容易出现回正超调的现象,提出了一种新型的回正与主动阻尼控制策略。该控制策略以功能原理为理论基础,可以随车速和转向盘转角的不同而调整回正力矩或阻尼力矩的大小。实车试验的结果证明,该控制策略能够改善车辆低速时的回正性,抑制车辆中高速时的回正超调现象,并且在施加了回正与主动阻尼控制后,驾驶员的操纵手感没有受到不良的影响。     

电动助力转向系统回正控制算法研究

提出了一种电动助力转向系统回正控制算法以提高转向盘的回正性。开发了一种基于转向盘转角估计的PID控制算法，该控制算法不需要转向盘转角或者电动机转速传感器，降低了控制系统的成本。同时，对提出的控制算法进行了仿真，并与其它回正控制算法的试验进行对比，结果证实此算法可提高转向盘的回正性和稳定性。     

装载机避障轨迹规划及模型预测轨迹跟踪

轮式装载机在工作区域行驶时,避障过程频繁,以往的避障轨迹规划未考虑整车转向半径约束和车速变化,也较少考虑整车在动力学模型条件下的轨迹跟踪性能.针对上述情况,以自动驾驶轮式装载机为对象,基于最优快速随机扩展树算法(RRT*),考虑车身膨胀圆个数,生成全局最优避障路径,以整车最小稳定转向半径为约束,利用CC-Steer算法...     

Nonlinear optimal integrated vehicle control using individual braking torque and steering angle with on-line control allocation by using state-dependent Riccati equation technique

This paper proposes the solution of state-dependent Riccati equation as a nonlinear optimal regulator to stabilise the motion dynamics of the vehicle model subjected to sudden disturbance inputs in the lateral direction. The proposed nonlinear regulator coordinates individually actuated wheel braking torque and steering wheel angle simultaneously in an optimal manner. Performance criteria are satisfied by solving the Riccati equation based on the given cost function subjected to the nonlinear vehicle dynamics. On-line control allocation in terms of optimal brake torque distribution enhanced by optimal wheel steering angle input is achieved. Furthermore, the proposed optimal nonlinear regulator is an active fault-tolerant control system against partial by-wire actuator failures while guaranteeing stability with good performance due to its capability to allocate the individual control inputs in an optimal way. The main aim is to stabilise the motion dynamics of the vehicle model during short-term emergency situations along the desired straight trajectory manageable by average drivers and to provide vehicle stability and handling predictability through the interaction of individual wheel braking and steering actuators. Simulation results are used to illustrate the effectiveness of the proposed methodology.     

Numerical Simulation of Vehicle Behavior during Straight Line Keeping on Undulating Road Surfaces

Numerical design of vehicles having optimal straight line stability on undulating road surfaces requires an accurate vehicle model based on knowledge of the relevant phenomena. Therefore, vehicle behavior on undulating straight roads has been analyzed and modeled. Measurements on a flat road surface have shown that the dedicated vehicle model yields accurate simulation results of the steering response to medium steering wheel angle inputs. In addition, the model has been validated by measuring two vehicle responses during normal driving on an undulating straight road: viz. the responses to the small steering wheel angle input and to the input by the global inclination of the road surface.     

基于MATLAB/Simulink的车辆转向稳定性的仿真研究

汽车的操纵稳定性是衡量汽车安全性最基本的指标之一,影响汽车行驶稳定性的基本因素主要有横摆角速度与质心侧偏角,将汽车简化为二自由度模型,建立关于横摆角速度与质心侧偏角的转向微分方程.基于MATLAB/Simulink软件建立仿真模型,对前轮转向与四轮转向典型的二自由度汽车模型进行仿真分析.对比两轮转向和四轮转向的稳定性....     

Low cost design of parallel parking assist system based on an ultrasonic sensor

This paper presents a low cost design and implementation of a parallel parking assist system (PPAS) based on ultrasonic sensors. Generally, a PPAS requires several types of sensors, such as an ultrasonic sensor, camera sensor, radar sensor and laser sensor for parking space detection. However, our proposed PPAS only requires two ultrasonic sensors on the front and lateral sides for parking space detection. Moreover, a steering angle sensor and wheel speed sensor installed in the vehicle are used to obtain vehicle position information for localization in ultrasonic range data. The hardware architecture of the PPAS based on an electronic control unit (ECU) module, sensor modules and a human machine interface (HMI) module was proposed. Moreover, the software architecture of the PPAS is based on system initialization, scheduling, recognition and a control algorithm. In particular, a novel sensor algorithm was proposed to minimize the vehicle corner error of the ultrasonic sensor. A prototype of the PPAS based on the proposed architecture was constructed. The experimental results demonstrate that the implemented prototype is robust and successfully performs parking space detection and automatic steering control. Finally, the low cost design and implementation of the PPAS was possible due to the cheap ultrasonic sensors, simple hardware design and low computational complexity of the proposed algorithm.     

Numerical Simulation of Vehicle Behavior during Straight Line Keeping on Undulating Road Surfaces

SUMMARY

Numerical design of vehicles having optimal straight line stability on undulating road surfaces requires an accurate vehicle model based on knowledge of the relevant phenomena. Therefore, vehicle behavior on undulating straight roads has been analyzed and modeled. Measurements on a flat road surface have shown that the dedicated vehicle model yields accurate simulation results of the steering response to medium steering wheel angle inputs. In addition, the model has been validated by measuring two vehicle responses during normal driving on an undulating straight road: viz. the responses to the small steering wheel angle input and to the input by the global inclination of the road surface.     

An Advanced Steering System with Active Kinesthetic Feedback for Handling Qualities Improvement

SUMMARY

Advanced Steering System with artificial steering wheel torque-active kinesthetic information feedback for improving handling qualities is discussed. Fundamentally the structure of the system may be considered to another form of model following control. In this system, a driver always remains in the control loop and receives steering control information which give him/her a direct hint to steer a steering wheel. This system works as a stability and control augmentation system of the vehicle to improve the vehicle handling qualities both in compensatory and pursuit control task, and is expected to reduce driver's workload. Effects of this system are analyzed in terms of man-machine system characteristics. Identification of driver dynamics was carried out to find why such improvement could be achieved. Availability of the proposed system is verified by analysis, simulator and proving ground tests.     

Steady-state steering of a tilting three-wheeled vehicle

The design of a narrow-track enclosed vehicle for urban transport was the subject of the CLEVER project. Due to its narrow track and requirement for car-like controls, an actively controlled tilting system was integrated into the chassis to allow for high lateral accelerations without rolling over. The cornering behaviour of this unique vehicle concept is investigated and compared with the ideal Ackermann response. The steer kinematics of this 1F1T (one front wheel, one wheel tilting) configuration are assessed through the use of a steady-state steering model, with attention focused on how steer parameters such as tilt axis height and inclination can be tuned to provide the required response. A prototype vehicle was designed and built and the results of experimental testing are presented to illustrate the real balancing performance of the combined steering and tilting approach used for the CLEVER vehicle. The experimental results follow the trends demonstrated in the model.     

直线行驶过程中汽车方向盘转角的研究分析

介绍了一种汽车方向盘转角传感器,搭建了汽车方向盘转角数据采集系统。依据在北京五环路上的行驶实验,分析了驾驶前期和后期方向盘转角特性的不同,得出驾驶员正常驾驶汽车直线行驶时方向盘转角范围约在其回正位置的左右7°之间,方向盘紧定时间在9s内。实验结果为驾驶行为研究、驾驶疲劳监测及相关产品的开发提供了参考。     

An Advanced Steering System with Active Kinesthetic Feedback for Handling Qualities Improvement

Advanced Steering System with artificial steering wheel torque-active kinesthetic information feedback for improving handling qualities is discussed. Fundamentally the structure of the system may be considered to another form of model following control. In this system, a driver always remains in the control loop and receives steering control information which give him/her a direct hint to steer a steering wheel. This system works as a stability and control augmentation system of the vehicle to improve the vehicle handling qualities both in compensatory and pursuit control task, and is expected to reduce driver's workload. Effects of this system are analyzed in terms of man-machine system characteristics. Identification of driver dynamics was carried out to find why such improvement could be achieved. Availability of the proposed system is verified by analysis, simulator and proving ground tests.     

分段式转向梯形断开点的优化设计

文章建立了某轮式车辆的前独立悬架和转向系统的参数化模型,阐述了分段式梯形断开点设计需要遵循的两点原则,分析了断开点三个方向坐标对阿克曼转向特性以及车轮跳动过程中前束角变化的影响,以实际外轮转角与理论外轮转角差值最小以及前束角变化最小为优化目标,对断开点位置进行了优化分析。研究结果表明,断开点坐标的优化可以改善车辆转向特性,同时提高转向系统与悬架系统的运动协调性,为轮式车辆转向梯形的设计提出了较为合理的优化方案。     

Development of yonden electric vehicle “PIVOT”

A project was carried out to develop an appealing new electric vehicle that features those dynamic capabilities, including such universal drive as point rotation and lateral drive, which cannot be achieved by conventional engine-powered vehicles. The new electric vehicle, called “PIVOT”, was realized through the development of special steering and suspension systems that can steer each wheel at an angle wider than 90 degrees either way, the development of a control unit that can separately control the traction force and steer angles for each wheel, and the use of drive unit with motor-in-the-wheel systems.     

Vehicle steering returnability with maximum steering wheel angle at low speeds

In this paper, an analytical model with suitable vehicle parameters, together with a multi-body model is proposed to predict steering returnability in low-speed cornering with what is expected to be adequate precision as the steering wheel moves from lock to lock. This model shows how the steering response can be interpreted in terms of vertical force, lateral force with aligning moment, and longitudinal force. The simulation results show that vertical steering rack forces increase in the restoring direction according to steering rack displacement for both the inner and outer wheels. As lateral forces due to side-slip angle are directed toward the medial plane of the vehicle in both wheels, the outer wheel pushes the steering wheel in the returning direction while the inner wheel does not. In order to improve steering returnability, it is possible to increase the total steering rack force in both road wheels through adjustments to the kingpin axis and steering angle. This approach is useful for setting up a proper suspension geometry during conceptual chassis design.     

基于功能安全的分布式驱动电动汽车前轮失效补偿控制

分布式驱动电动汽车可以实现四轮转矩分配和差动转向,提升整车的动力学控制性能和经济性,但是四轮转矩独立可控的特点也对功能安全提出挑战.当前轮单侧电机出现执行器故障失效情况时,不仅会产生附加横摆力矩降低车辆安全性,差动转向功能的存在还会使车辆严重偏航.基于此,在设计分布式驱动-线控转向一体化底盘的基础上,基于功能安全提出一...     

Yaw rate and side-slip control considering vehicle longitudinal dynamics

Most conventional vehicle stability controllers operate on the basis of many simplifying assumptions, such as a small steering wheel angle, constant longitudinal velocity and a small side-slip angle. This paper presents a new approach for controlling the yaw rate and side-slip of a vehicle without neglecting its longitudinal dynamics and without making simplifying assumptions about its motion. A sliding-mode controller is used to develop a differential braking controller for tracking a desired vehicle yaw rate for a given steering wheel angle, while keeping the vehicle’s side-slip angle as small as possible. The trade-off that exists between yaw rate and side-slip control is described. Conventional and proposed algorithms are presented, and the effectiveness of the proposed controller is investigated using a seven-degree-of-freedom vehicle dynamics model. The simulation results demonstrate that the proposed controller is more effective than the conventional one.     

电动助力转向系统回正控制策略研究

在分析电动助力转向系统回正模型的基础上,提出了电动助力转向回正控制算法。尝试直接采用扭矩信号作为转向盘转角估计的依据,并以此为基础提出不需配置转角传感器的回正控制策略。在matlab中建立了电动助力转向系统的模型,并利用Simulink工具箱对算法进行了仿真。仿真结果表明,所提出的回正控制策略能提高转向盘的回正性能,并为台架试验打下了基础。     

Additional 4WS and Driver Interaction

This investigation is based on a complex 4-wheel vehicle model of a passenger car that includes steering system and drive train. The tyre properties are described for all possible combined longitudinal and lateral slip values and for arbitrary friction conditions. The active part is an additional steering system of all 4 wheels, additionally to the driver's steering wheel angle input. Three control levels are used for the driver model that thereby can follow a given trajectory or avoid an obstacle.

The feedback control of the additional 4 wheel steering is based on an observer which can also have adaptive characteristics. Moreover a virtual vehicle model in a feedforward scheme can provide desired steering characteristics.

To get information for critical situations a cornering manoeuvre with sudden u-split conditions is simulated. Further a similar manoeuvre is used to evaluate the reentry in a high friction area from low friction conditions. And finally the performance of the controller is shown in a severe lane change manoeuvre.