帕萨特领驭轿车定速巡航系统浅析与维修

以使用维修为切入点,阐述帕萨特领驭轿车定速巡航控制系统的组成、控制原理、对系统进行电路分析,基于电路分析给出维修思路和故障案例。     

The bricycle: a bicycle in zero gravity can be balanced or steered but not both

A bicycle or inverted pendulum can be balanced, that is kept nearly upright, by accelerating the base. This balance is achieved by steering on a bicycle. Simultaneously one can also control the lateral position of the base: changing of the track line of a bike or the position of hand under a balanced stick. We show here with theory and experiment that if the balance problem is removed, by making the system neutrally stable for balance, one cannot simultaneously maintain balance and control the position of the base. We made a bricycle, essentially a bicycle with springy training wheels. The stiffness of the training wheel suspension can be varied from near infinite, making the bricycle into a tricycle, to zero, making it effectively a bicycle. The springy training wheels effectively reduce or even negate gravity, at least for balance purposes. One might expect a smooth transition from tricycle to bicycle as the stiffness is varied, in terms of handling, balance and feel. Not so. At an intermediate stiffness, when gravity is effectively zeroed, riders can balance easily but no longer turn. Small turns cause an intolerable leaning. Thus there is a qualitative difference between bicycles and tricycles, a difference that cannot be met halfway.     

凌志400型汽车稳定性控制系统结构及原理解析

对凌志400汽车上采用的稳定性控制系统(VSC)在结构和原理上进行分析,探讨抑制汽车过量不足或过多转向的办法。     

Robust state feedback stabilization of articulated steer vehicles

In this work, a full-state feedback controller is designed to prevent the oscillatory instability or snaking behaviour of an articulated steer vehicle. To design the controller, first, a linearized model of the vehicle is developed and analyzed to identify the most important uncertain tire parameters with regard to the snaking mode. By using this linearized model, the equations of motion are represented in the form of a polytopic system, which depends affinely on the most important uncertain tire parameters. Then, by solving some linear matrix inequalities, both the Lyapunov and state feedback matrices for the robust stabilization of the vehicle are found. The performance of the resulting controller is evaluated by conducting several simulations based on the linearized model. To verify the results from the linearized model analysis, some simulations are also done by a virtual prototype of the vehicle in ADAMS. The results based on the linearized model are reasonably consistent with those from the simulations in ADAMS. They show that the controller can effectively stabilize the vehicle during the snaking mode in different driving conditions.     

Straight-ahead running of road vehicles – analytical formulae including full tyre characteristics

ABSTRACT

During straight-ahead running, the longitudinal axis of road vehicles, notably cars, is not parallel to road axis. This occurrence is general and is due both to road cross slope (road banking) and to tyre characteristics, particularly ply-steer and conicity. In order to describe such a phenomenon, the paper develops a new and relatively simple analytical model. Despite the model is linear, the solution which is provided is exact, since straight-ahead motion occurs with small angles and both the elastokinematics of suspension system and tyre characteristics can be modelled by linearised equations. The Handling Diagram theory is updated and completed by introducing the actual shifts of tyre characteristics. The validation of the analytical expressions is performed by using a MSC Adams^TM full model of a car. A subjective-objective experimental test campaign provides preliminary substantiation of the ability of the derived formulae to describe tyre performance. By means of the unreferenced analytical formulae developed in the paper, we allow, given the vehicle, the proper tyre design specification and vice-versa. In particular, a formula is given to make null the steering torque during straight-ahead driving. The derived analytical formulae may provide a sound understanding of the straight-ahead running of road vehicles.     

Elaboration and quantitative assessment of manoeuvrability for motorcycle lane change

The desire to quantitatively assess vehicle manoeuvrability and handling has led to the development of various expressions, or metrics, which typically relate system input to system output. With regard to motorcycle manoeuvrability, a notable example of such a measure, or metric, is the Koch index [Koch, J., 1978, Experimentelle und Analytische Untersuchungen des Motorraad-Fahrer Systems. Dissertation, Berlin.]. This article describes the development of a new metric applied to lane change (LC) tests and coined ‘LC roll index’. This metric takes into account the peak-to-peak values of the rider-input steering torque divided by the peak-to-peak roll rate response of the vehicle and normalizes this quantity by the forward velocity. In addition to this new metric, an analytical expression is developed, which in many cases summarizes a motorcycle’s LC performance in a single, terse, analytical term. Experimental results are presented for three vastly different motorcycles: a scooter, a street, and a touring motorcycle performing variations of the LC manoeuvre. Numerous test runs for each vehicle are analysed and the results are summarized along with those presented in the recent literature. Finally, simulation results are presented to highlight the correlation between the proposed indices and handling.     

On the handling performance of a vehicle with different front-to-rear wheel torque distributions

ABSTRACT

The handling characteristic is a classical topic of vehicle dynamics. Usually, vehicle handling is studied by analyzing the understeer coefficient in quasi-steady-state maneuvers. In this paper, experimental tests are performed on an electric vehicle with four independent motors, which is able to reproduce front-wheel-drive, rear-wheel-drive and all-wheel-drive (FWD, RWD and AWD, respectively) architectures. The handling characteristics of each architecture are inferred through classical and new concepts. The study presents a procedure to compute the longitudinal and lateral tire forces, which is based on a first estimate and a subsequent correction of the tire forces that guarantee the equilibrium. A yaw moment analysis is performed to identify the contributions of the longitudinal and lateral forces. The results show a good agreement between the classical and new formulations of the understeer coefficient, and allow to infer a relationship between the understeer coefficient and the yaw moment analysis. The handling characteristics vary with speed and front-to-rear wheel torque distribution. An apparently surprising result arises at low speed: the RWD architecture is the most understeering configuration. This is discussed by analyzing the yaw moment caused by the longitudinal forces of the front tires, which is significant for high values of lateral acceleration and steering angle.     

Lane-keeping benefits of practical rear axle steer

The classic two-degree-of-freedom yaw-plane or ‘bicycle’ vehicle model is augmented with two additional states to describe lane-keeping behaviour and further augmented with an additional control input to steer the rear axle. A simple driver model is hypothesised where the driver closes a loop on a projected lateral lane position. The driver can select the preview distance to compensate driver/vehicle dynamics, consistent with the ‘cross-over’ model found in the literature. A rear axle steer control law is found to be a function of the front axle steering input and vehicle speed that exhibits stability similar to a positive-real system, while at the same time improving the ability of the driver/vehicle system to track a complex curved lane and improving steady-state manoeuvrability. The theoretically derived control law bears similarity to practical embodiments allowing a deeper understanding of the functional value of steering a rear axle.     

Elaboration and quantitative assessment of manoeuvrability for motorcycle lane change

The desire to quantitatively assess vehicle manoeuvrability and handling has led to the development of various expressions, or metrics, which typically relate system input to system output. With regard to motorcycle manoeuvrability, a notable example of such a measure, or metric, is the Koch index [Koch, J., 1978, Experimentelle und Analytische Untersuchungen des Motorraad-Fahrer Systems. Dissertation, Berlin.]. This article describes the development of a new metric applied to lane change (LC) tests and coined 'LC roll index'. This metric takes into account the peak-to-peak values of the rider-input steering torque divided by the peak-to-peak roll rate response of the vehicle and normalizes this quantity by the forward velocity. In addition to this new metric, an analytical expression is developed, which in many cases summarizes a motorcycle's LC performance in a single, terse, analytical term. Experimental results are presented for three vastly different motorcycles: a scooter, a street, and a touring motorcycle performing variations of the LC manoeuvre. Numerous test runs for each vehicle are analysed and the results are summarized along with those presented in the recent literature. Finally, simulation results are presented to highlight the correlation between the proposed indices and handling.     

ZK6831H型客车高速发飘的研究

当后置客车达到一定速度时,操纵稳定性变差已成为客车行业面临的技术难题之一。本文探讨-8m客车高速操纵稳定性变差产生的原因以及解决的办法。