DE102005037479A1 - Vehicle dynamics control system for a two-lane motor vehicle - Google Patents

Abstract

The invention relates to a driving dynamics control system for a two-lane motor vehicle, the transverse dynamics and / or yaw dynamics and / or longitudinal dynamics of which can be changed independently of or in addition to a specification by the driver by the control system and / or of the vehicle structure of which the lifting dynamics and / or the The pitch dynamics and / or roll dynamics can be changed by the control system independently of or in addition to forces resulting from the driver's specifications, with between two and six changeable degrees of freedom thus being available, and the behavior of the vehicle with regard to these degrees of freedom is determined by different actuators controlled by the control system. For at least two degrees of freedom, the transfer functions of a model-based pilot control can be set independently of one another to different values as a function of a specification by the driver, which values are then implemented by a corresponding number of actuators on the vehicle. A target driving behavior of the vehicle can be set by means of physically interpretable actuators with regard to bandwidth, damping, stationary behavior and zeroing of the transfer function between a steering angle preset by the driver and the float angle and / or yaw rate and / or lateral acceleration of the vehicle.

Description

The The invention relates to a driving dynamics control system for a two-lane Motor vehicle whose transverse dynamics and / or yaw dynamics and / or longitudinal dynamics independently from or in addition to a specification of the driver by the control system changeable is and / or of the vehicle body, the hub dynamics and / or the pitch dynamics and / or roll dynamics independent of or in addition to from the driver's specifications resulting forces by the control system changeable is, whereby there are between two and six variable degrees of freedom, and the behavior of the vehicle with respect to these degrees of freedom by different actuators controlled by the control system is determined.

Known are a variety of vehicle dynamics control systems, with which a targeted change of Driving dynamics of a two-lane motor vehicle, and in particular from the transverse dynamics and yaw dynamics is possible. These control systems use different actuators or different Intervention principles. So can the steered front wheels through Setting an additional steering angle or the total steering angle a stabilizing Yaw moment be applied. But this is also through bodies a steering angle to possibly slightly steerable wheels of Rear axle possible. Possible is an application of a stabilizing yaw moment as well by targeted distribution of the drive torque or the so-called drag torque of the vehicle drive unit between the left and the right Fzg. Side both on the front axle and on the rear axle of the vehicle by means of suitable coupling controls. Also by wheel-specific modulation of the brake pressure to the individual wheels a stabilizing yaw moment can be generated, as well as through modulation the roll stiffness distribution between front axle and rear axle, by redistributing the over transmitted the wheels Longitudinal forces of the Vehicle drive unit between front axle and rear axle.

In the known prior art, at least in terms of the lateral dynamics and yaw dynamics of the vehicle usually a control, ie, a target-actual comparison, wherein it is ensured that a predetermined by the driver steering request is implemented in a suitable manner. In the German Offenlegungsschrift DE 102 36 734 A1 Furthermore, a method is described for guiding a multi-lane vehicle on a curved path, which in the form of a pre-control of two input variables, namely the driver-specified steering angle and the current vehicle speed, actuates two actuators, namely one of the steerable (front) wheels of the vehicle steering actuator and any suitable actuator, with which the longitudinal force distribution between the Fzg. wheels of the two Fzg.seiten is designed differently.

With The present invention will now be a further improvement a precontrol of the vehicle behavior are shown (= task), although in the detailed explanations analogous to the just mentioned State of the art assumed a steering specification of the Fzg driver and thus, in particular, the lateral dynamics and yaw dynamics of the Vehicle is relevant, but the present invention is simple to the other degrees of freedom of a two-lane motor vehicle transferable is, namely both on its longitudinal dynamics, as well as on the hub dynamics and / or the pitch dynamics and / or the Roll dynamics of the vehicle body.

The solution this task is for a vehicle dynamics control system according to the preamble of the claim 1 characterized in that for at least two (of the said) degrees of freedom the transfer functions a model-based Pilot control in dependence from a specification of the driver independently to different Values are adjustable, which are then counted by an appropriate number be implemented by actuators on the vehicle. Advantageous developments are content of the subclaims.

According to the invention can (again based on the example of steering by the driver, ie based on a steering angle specification and the affected transverse dynamics and yaw dynamics of the vehicle) via at least two independent actuators (or control capabilities) at least in the linear range of dynamic vehicle behavior, the two Degrees of freedom of the lateral dynamics and the yaw dynamics of the motor vehicle via a coordinated pilot control are set independently. Thus, if all the wheels of the vehicle are steerable, for example, be set in extreme cases that the vehicle on a steering input of the driver out no yaw, but at a slip angle of 0 ° only a transverse movement (of course, in addition to the longitudinal movement) performs. Of course, however, such extreme conditions are not shown; However, it should be possible to be able to represent different proportions of yawing and transverse movement within reasonable limits in the example, and independently. Should the vehicle with the illustrated yawing motion and transverse movement can no longer be moved along the desired curved path, the driver can adjust his steering specification accordingly.

With a proposed vehicle dynamics control system is so to speak any behavior of the vehicle representable, and in particular in that for at least two (the possible) Degrees of freedom independently mutually different responses to a specification of the driver can be adjusted over different transfer functions a model-based Feedforward control, whereupon later Move even closer will be received. In the prior art, however, are not methods for the control engineering design of a vehicle dynamics control known, the one systematic design of a control system for realization For example, a desired lateral dynamics and a desire yaw dynamics of a Describe vehicle by means of a pilot control. Otherwise it is in the control systems on the market (for example ESP or in the so-called. Active steering of the Applicant) not the goal, the lateral dynamics and yaw dynamics independent from each other. Due to existing in the art Restrictions this is due to the present controller structures and the pursued goals practically impossible.

deviant from the already cited example case of a different Adjustment of the lateral dynamics and the yaw dynamics of a motor vehicle is in the context of a generalization, the mode of action of a corresponding Vehicle dynamics control system in the presence of suitable actuators basically transferable to all possible degrees of freedom a vehicle chassis. So can or can in addition to or alternatively for lateral dynamics or yaw dynamics also the longitudinal dynamics of the vehicle as well the stroke dynamics and / or the pitch dynamics and / or the roll dynamics be controlled according to the vehicle body. Basically So any combination of the six possible degrees of freedom of a motor vehicle be controlled accordingly, by default of one corresponding number of desired transfer functions (for this Degrees of freedom).

These transfer functions (or desired transfer functions) pose as well as the fact that it is a model-based feedforward is, characterizing features of claim 1. It can the model-based feedforward control in principle build on any models; but preferably comes (known to those skilled) so-called linear Einspurmodell used, otherwise can also be extended appropriately, so for example in terms of longitudinal dynamic influences or in terms of dynamic lateral force and / or roll dynamics of the vehicle. Furthermore let yourself the dynamic driving behavior of the vehicle (especially with regard to lateral dynamics and yaw dynamics) not only in the linear range, but also limited in the so-called transition area to the so-called tire saturation (The latter is the area in which, despite increasing the wheel slip angle no further increase the Radseitenkraft can be achieved) by a linear Einspurmodell describe. Priority should, however, the setting of different Values of the transfer functions for the Linear range of dynamic vehicle behavior may be possible.

A transfer function in the sense of the present explanation now describes the relationship between a variable predefined by the driver and the corresponding vehicle response thereto. So much simplified is the context Y = G _Y · X, where X is the default of the driver, ie, for example, a default steering angle, Y the behavior of the vehicle thereon, so for example, the yaw rate and / or the slip angle and / or Transverse acceleration, and G _Y the associated transfer function or transfer matrix or vector, according to the invention for at least two degrees of freedom, the transfer functions are adjustable to different values. (The symbol "·" stands for a multiplication.) The individual transmission functions preferably contain a proportion or factor describing the stationary behavior of the vehicle and a component or factor describing the (dynamic) instationary behavior of the vehicle Oscillation equation (or in other words by a vibration equation in the broad sense) be described, which contains or contain as characteristic quantities, at least in analogy to a vibration equation, inter alia, the vibration bandwidth or the natural frequency, a damping factor and the zeros.

As regards the actuators, with which the behavior of the vehicle can be adjusted as desired, these may be all actuators or actuators, which will be described in connection with the explanation of the plurality of known vehicle dynamics control systems, the influence on the lateral dynamics and the yaw dynamics have already been mentioned. For influencing the roll dynamics, stroke dynamics and pitch dynamics, further actuators basically known to the person skilled in the art may be provided. In this case, the actuators are preferably also selected such that these actuators are approximately equally distributed over the two axles of the vehicle for influencing two or more degrees of freedom. Is it the ones to be influenced? Degrees of freedom (again, as always exemplified) to the lateral dynamics and the yaw dynamics of the vehicle, it is advantageously of a first possibility of engagement on the front axle and a second possibility of engagement on the rear axle, either via the steering and / or the drive and / or To go out brakes in any combination. In principle, although two Verstelling opportunities on a (common) axis can be used, but this is unfavorable from a practical point of view, since at tire saturation on this axis the actuating efficiency of both actuators would be lost, while in the case of distribution on two axes in the case of saturation of an axis at least the Actuating the actuator remains on the other axis. Furthermore, as a rule, the actuators of one axle influence one another. While in the linear region of the vehicle behavior preferably steering and / or Rad longitudinal forces applying actuators are used, in the (already mentioned above) transition area due to a realization of a longitudinal force distribution between the front and rear axle and / or an influence of the Vertical dynamics of the vehicle and ultimately on intervention in the power output or torque output of Fzg. Drive unit possible.

The hereby proposed different transfer functions for at least two degrees of freedom in the control system automatically depending on boundary conditions, in particular dependent on from the driving speed and / or the driver predetermined steering angle be specified. Alternatively or additionally, it is also possible that different transfer functions, which have an effect on at least two degrees of freedom, by the Driver are specifiable, with the possibility of specifying any Values not favorable appears, but the possibility should be to make a choice among discrete values.

in the returning to the preferred example case again, namely that a desired yaw rate and / or a wish-slip angle and / or a desired lateral acceleration or desired transmission functions (or desired transmission behavior) for the Yaw rate (dynamic and / or stationary) and for the slip angle (dynamic and / or stationary) should be specifiable, so can theoretically, a large number of parameters can be specified freely. If, for example - like already stated above - the transfer functions one the stationary behavior of the vehicle describing share as well as the (dynamic) transient response of the vehicle, the latter being the be described by a vibration equation in the broadest sense can, as sizes u.a. the vibration bandwidth or the natural frequency, a damping factor and contains the zeros, so receives you already for these two degrees of freedom using two independent actuators (namely for example for a front-wheel steering as well as for a rear wheel steering) 16 parameters. In each case for the front axle actuator and for the rear axle actuator fall then namely as well as the yaw rate as well the float angle in each case 4 parameters, namely in each case the so-called. Stationary part and the three named transient shares.

there it is quite possible that a target driving behavior of the vehicle by means of physically interpretable Steller in terms of bandwidth, attenuation, stationary behavior and zeroing the transfer functions between a driver's steering angle specification and the slip angle and / or the yaw rate of the vehicle can be adjusted, so in particular in the context of the interpretation of a specific vehicle dynamics control system a specific vehicle or vehicle type. For example, one could Applicator quite 16 knobs or the like for the 16 parameters mentioned in the previous paragraph are provided, namely under the said physical interpretation.

It However, it may well be that a free selectability for all parameters in reality at all is not feasible because, for example, the respective actuator of a corresponding Default can not follow, for example, because its momentum is insufficient (in terms of bandwidth or because of rate limit) and / or because the required body energy is too high. It is therefore proposed the specification of the mentioned parameters relative to the passive driving behavior make. This results in a simple intuitive parameterization, for example, if a default in a percentage change to the behavior of a conventional, uncontrollable driving behavior of the vehicle can be made. With moderate requirement (for example 10% change) the respective actuator is not overwhelmed.

In the context of this, therefore, the conventional driving behavior in the linear range and transition range can first be identified. In this case, the data for the linear Einspurmo dell can be determined either once by means of identification and from these the equivalent parameters or maps are calculated, which are required for the determination of the transfer functions. However, it is also possible to directly identify gradients of these parameters over the driving speed (and / or over the predetermined steering angle and / or over the steering angle speed or the like) in driving tests. Subsequently, a desired dynamics can be set relative to these variables, but with times the possibility exists, an adaptation eg. To travel speed and / or steering angle specification and / or steering angle speed (or in dependence on these and / or other sizes) make. The 16 parameters already mentioned above by way of example can then be interpreted as physical "rotary buttons" with which the desired behavior of the vehicle can be determined, preferably in relation (for example by% data) to the conventional vehicle (whose transmission functions are not In order to reduce the complexity, it may make sense to group together those parameters which describe the dynamic portion of the transfer functions, each in a "rotary knob", ie returning to the already mentioned oscillation equation analogy only one rotary knob at a time for the bandwidth or for the attenuation or for the zeros.

One proposed vehicle dynamics control system is quite combinable or compatible with existing methods for longitudinal dynamics compensation, i.e. a compensation of the longitudinal dynamics influences the lateral dynamics and the yaw dynamics is at least two when controlled Actuators possible at the same time. Furthermore, a combination with usual Driving stabilization regulations or yaw rate regulations simple possible. advantageously, is an interpretation of the proposed feedforward with different Controller structures possible, so over inverse model precontrol or 2DOF structure (= two degrees of freedom) or over P / PID controller or a regulated pilot model, respectively stationary and / or dynamic. Also, a compensation of the actuator dynamics on inverse Models (linear, non-linear) or other structures (controlled pilot control, 2DOF structure, PID controller) can be used if the actuator dynamics (eg, in terms of bandwidth and positioning rate) not sufficiently fast is, it should be noted that quite a variety may differ from the above explanations, without the content of the claims to leave.

Basically (related on the several times mentioned preferred application) allows a proposed control system free design of the lateral dynamics and yaw dynamics of a vehicle in the linear range of driving behavior and restricted also in its transition area. The Desired driving behavior can be achieved by means of physically interpretable "buttons", for example for bandwidth, damping, stationary behavior and zeros regarding transmission behavior between steering instruction by the driver and slip angle, yaw rate and / or Transverse acceleration of the vehicle can be adjusted. So that can the vehicle in principle any transverse dynamics and yaw dynamics (dependent on the actuator dynamics and rate constraints). One with a system according to the invention equipped vehicle can thus the driving behavior of a (any) other (even virtual) vehicle to be imprinted (at least in presence a sufficient actuator dynamics). This feature can be a Differentiation of driving behavior by using different Parameterizations performed be, in the simplest case in the form of a so-called driving dynamics switch. A free specification of the lateral dynamics and the yaw dynamics causes this Freely definable lateral and yaw behavior in the linear range and in the transition range the tire, a forward-looking stabilization by feedforward, the Avoidance of driver-induced vibrations, easier controllability of the vehicle by enlarging the Linear range as well as an increased Stability reserve.

Claims (11)

Vehicle dynamics control system for a two-lane motor vehicle whose lateral dynamics and / or yaw dynamics and / or longitudinal dynamics is variable independently of or in addition to a specification of the driver by the control system and / or the vehicle body, the hub dynamics and / or the pitch dynamics and / or the rolling dynamics can be varied independently of or in addition to forces resulting from the driver's specifications by the control system, there thus being between two and six variable degrees of freedom, and the behavior of the vehicle with respect to these degrees of freedom is determined by different actuators controlled by the control system, characterized in that for at least two degrees of freedom, the transfer functions of a model-based precontrol in dependence on a specification of the driver are independently adjustable to different values, which then by a corresponding number of actuators on F be implemented. Vehicle dynamics control system according to claim 1, characterized characterized in that the setting of different transfer function values priority for the linear range of dynamic vehicle behavior is possible. Vehicle dynamics control system according to claim 1 or 2, characterized in that with respect to the two degrees of freedom and lateral dynamics dynamic yaw control of the driver two independent actuators by a coordinated pilot control, in the corresponding transfer functions stationary and / or transient within meaningful limits independently be set differently from each other, are controlled. Driving dynamics control system according to one of the preceding Claims, characterized in that one of the actuators on the front axle of the vehicle and the other or another on the rear axle the vehicle is effective. Driving dynamics control system according to one of the preceding Claims, characterized in that actuators for adjusting wheel steering angles at the Front axle and / or rear axle are provided and / or actuators for applying different longitudinal wheel forces the two sides of an axle or the vehicle. Driving dynamics control system according to one of the preceding Claims, characterized in that different transfer functions for at least two degrees of freedom depending of boundary conditions, in particular of the driving speed and / or from the driver specified steering angle and / or from the given Steering angular velocity can be specified. Driving dynamics control system according to one of the preceding Claims, characterized in that different transfer functions, the affect at least two degrees of freedom, by the driver can be specified. Vehicle dynamics control system according to claim 7, characterized characterized in that different transfer function by specifying of the relationship to the conventional, uncontrollable driving behavior of the vehicle can be specified. Driving dynamics control system according to one of the preceding Claims, characterized in that the transfer functions a the stationary behavior descriptive factor and a (dynamic) instationary behavior descriptive factor included. Driving dynamics control system according to one of the preceding Claims, characterized in that the the (dynamic) transient behavior descriptive factor of the transfer functions described by a system of equations in the manner of a vibration equation is, the or the like as sizes u.a. the bandwidth, a damping factor and contains the zero. Driving dynamics control system according to one of the preceding Claims, characterized in that a target driving behavior of the vehicle by means of physically interpretable controller in terms of bandwidth, Damping, stationary behavior and zeroing the transfer function between a driver's steering angle specification and the slip angle and / or the yaw rate and / or the lateral acceleration of the vehicle is adjustable.