DE10359216A1 - Adapted to the roll behavior of a vehicle vehicle dynamics control system - Google Patents

Abstract

The invention relates to a device and a method for stabilizing a vehicle in a situation critical to a fall, in which various controller input variables (ay, day / dt, P) are detected by means of a sensor system (2, 6) and a tilt stabilization algorithm (4, 5) by means of a Actuator (3, 9, 10) engages in the driving operation to stabilize the vehicle. In order to be able to take account of different loading states of the vehicle, a tilt tendency (K1) of the vehicle is estimated from the relationship between a variable describing the steering behavior of the vehicle and a variable describing the roll behavior of the vehicle, and this is taken into account in the tilt stabilization.

Description

The The invention relates to a method for stabilizing a vehicle in a situation critical to tilting according to the preamble of the claim 1, as well as a vehicle dynamics control system for tilt stabilization of a Vehicle according to the preamble of claim 9.

Vehicles with a high center of gravity, such as minivans, SUVs (Sport Utility Vehicles) or vans, especially when cornering with too high lateral acceleration tend to tilt about the longitudinal axis. In such vehicles, tilt stabilization systems, such as ROP (Roll-Over-Prevention) or ROM (Roll-Over-Mitigation) are therefore often used, which stabilize the vehicle in dynamic driving critical situations and reduce the tilting movement of the vehicle about the longitudinal axis. A known from the prior art vehicle dynamics control system with ROP function is exemplary in 1 shown.

1 shows a highly simplified schematic block diagram of a known ROP system, which is essentially a controller 1 with a ROP control algorithm, a sensor system 2 for detecting a tilt-critical driving state and an actuator 3 for performing a stabilization engagement. Detects the controller 1 Due to the sensor signals a situation critical to tilting, for example, intervenes by means of a brake on the outside front wheel in the driving. Other systems also operate by means of another actuator, such as an active spring / damper system (normal force distribution system) or an active steering system in the driving operation.

at Known Kippstabilisierungssystemen is a tilt-critical situation usually recognized by a descriptive of the lateral dynamics of the vehicle Size (the hereinafter referred to as indicator size S. is determined) and threshold monitored. That the indicator size becomes compared with a characteristic threshold and when exceeded the threshold carried out a stabilization intervention. The Indicator size usually determines also the strength stabilization intervention.

The Indicator size is in usually a function of the lateral acceleration ay, the temporal change the lateral acceleration day / dt of the vehicle and possibly further Influencing factors P.

2 shows the various input variables that are included in the calculation of the indicator size S. As can be seen, the inputs ay, day / dt, P become according to a function 4 linked and from the indicator size S calculated. The thus obtained indicator quantity S finally becomes the control algorithm 5 fed. The enabling or disabling of the tilt stabilization algorithm 5 is thus linked to the amount of lateral acceleration or its gradient.

The tilting behavior of a vehicle is in addition to the structural properties of the vehicle essentially dependent on the load. In addition, design features such as the suspension, age-related change and thus affect the tendency of the vehicle tilt. Such influences are at the in 1 not considered considered vehicle dynamics control with tilt stabilization function ROM or ROP.

Known Tilt stabilization functions ROP and ROM are therefore particular for SUVs or Pickup truck often very sensitive, i. tuned to high loading conditions and soft suspension. A stabilization intervention is therefore already at very low Lateral acceleration values triggered. This has the disadvantage that at normal or low load the tilt stabilization interventions take place too early and too hard.

It It is therefore the object of the present invention to provide a tilt stabilization method for vehicles, and to provide a corresponding vehicle dynamics control system, with the the rolling behavior of the vehicle learned simply and reliably and thus a different load or a different one technical condition of the vehicle as part of a tilt stabilization considered can be.

Is solved this task according to the invention by the specified in claim 1 and in claim 8 Characteristics. Further embodiments of the invention are the subject of dependent claims.

One essential aspect of the invention consists of a steering behavior descriptive size (e.g. the steering angle or the steering speed) and the roll behavior descriptive size (e.g. the roll rate or the spring deflection) information about the Tipping tendency (in the following only "tilting tendency") of a vehicle estimate and the tilt stabilization system to the thus determined tilt tendency adapt. The tilting tendency of the vehicle is preferably after every start (ignition a) of the vehicle in the course of driving re-learned and at considered the tilt stabilization.

The Evaluation of the relationship between the behavior describing the steering behavior Size (below referred to as the steering size) and the size describing the roll behavior (hereinafter referred to as roll size) has the advantage that the tendency to tilt (or roll stability) of the vehicle especially reliable estimated can be and thus different loading conditions or a modified considered technical condition in the vehicle dynamics control can be.

The determined tilt tendency can e.g. directly into the calculation of Incorporate indicator size S and thus the triggering time or deactivation time of the stabilization intervention.

Optional can the information about the tendency to tilt also contribute to the tilt stabilization algorithm and a characteristic property or size of the algorithm, e.g. an approach threshold, a control deviation, e.g. for a wheel slip, or a manipulated variable, such as e.g. the braking torque or the engine torque influence. The mentioned Characteristic properties or sizes are thus a function the tilting tendency. At high tilt tendency, i. high center of gravity or poor suspension, thus stabilization intervention can be initiated earlier or with stronger Extent to be carried out as with low tilt tendency.

to Determining the tilting tendency of the vehicle can be both the static as well as the dynamic relationship between a steering and a Wank size evaluated become. Preferably, at least dynamic driving situations, such as e.g. dynamic cornering, evaluated with regard to the tilt tendency and thus during the ride, the actual tilt tendency of the vehicle always determined more precisely.

at the steering size is in particular, the (measured) steering angle or a result derived size, like e.g. the steering speed. The roll size includes e.g. the wheel-upforce, the Spring way for individual wheels that Vertical acceleration or the roll angle, or derived therefrom Sizes, like e.g. the change the compression travel or the roll rate (change the roll angle).

In a stationary one Driving situation is preferably the relationship between the steering angle and a static roll size, like e.g. the compression travel of individual wheels evaluated and estimated a tendency to tilt.

In a dynamic driving situation is e.g. the connection between the steering speed and a dynamic roll size, such as e.g. the roll rate, evaluated.

Next The purely static or dynamic consideration can also be the dynamic change a roll size in one stationary Driving situation are evaluated. In a stationary cornering e.g. shows a vehicle depending on the load condition or condition of the suspension a different vibration behavior about the longitudinal axis. The tilt tendency or roll stability of the vehicle can thus also by evaluation of the amplitude and / or frequency of the oscillation a roll size over the Time appreciated become.

According to one preferred embodiment The invention is based on the steering and the roll size by means of fuzzy logic Tilting indicator determined that indicates the tipping tendency of the vehicle.

Of the Tipping indicator may additionally be weighted with a rating function that improves the quality of the learning process considered and thus a measure of reliability of the calculated tilt indicator. The evaluation function evaluated preferably the number of learning operations and / or their duration while a ride. This ensures in particular that the Tilt tendency under difficult estimation conditions not falsely too little appreciated becomes.

The estimate the tilting tendency is preferably carried out only in predetermined driving situations, the e.g. in terms of the steering angle, the lateral acceleration or another the lateral dynamics Description of a vehicle size certain predetermined conditions fulfill. This ensures that the result of the estimation is as possible reliable is.

To a restart of the vehicle is the tendency to tilt or tipping indicator preferably initialized to a value that has a high tendency to tilt of the Vehicle represents and thus an early one and causes rather strong intervention of the tilt stabilization algorithm. Only with increasing driving time and thus after some learning phases adjusts a tilt indicator, which represents the actual load condition.

Become strong within one or more learning phases (driving situations) determined different Kippindikatoren, preferably that is selected and based on the vehicle stabilization, which has the highest tendency to tilt represents.

The invention will be explained in more detail below with reference to the accompanying drawings tert. Show it:

1 a schematic block diagram of a known Kippstabilisierungssystems;

2 a schematic representation of the formation of an indicator size S of a tilt stabilization algorithm;

3 a block diagram of a tilt stabilization system according to an embodiment of the invention; and

4 a block diagram showing the generation of a Kippindikators K1.

Regarding the explanation of 1 and 2 Reference is made to the introduction to the description.

3 shows a schematic block diagram of a tilt stabilization system. The system includes a controller 1 with a tilt stabilization algorithm ROM (Roll Over Mitigation), a sensor system 2 . 6 for detecting driving state variables, and actuators 9 . 10 with which stabilization interventions are implemented. The blocks 4 . 7 . 8th are realized in software and serve the processing of the sensor signals (block 7 ), the estimate of the tendency to tilt or roll stability of the vehicle (Block 8th ) and the generation of an indicator size S (block 4 ).

To determine a ride-critical driving situation, the tilt stabilization system uses the existing ESP sensor technology 2 , This includes in particular wheel speed sensors, a steering angle sensor, a lateral acceleration sensor, etc. The sensor signals are in block 7 further processed and thereby in particular suppressed and filtered. Preferably, a plausibility monitoring of the sensor signals is performed.

Selected signals, namely the lateral acceleration ay, its gradient day / dt and optionally further influencing variables P flow into the block 4 , Therein, as above. 2 has been described, an indicator quantity S is calculated, with which the release or deactivation of stabilization measures is controlled. The indicator size also determines the strength of the stabilization intervention.

In addition to the ESP sensor technology 2 The tilt stabilization system can provide additional sensors 6 to measure a roll size. The sensors 6 Thus, for example, a sensor for measuring the wheel contact forces, the compression travel, the vertical acceleration or the roll rate or a derived therefrom size, such as the respective gradient include. The sensor signals are in block 7 processed and then the fuzzy information processing 8th fed. The block 8th receives as inputs at least one steering and one roll size.

at the steering size is it is in particular the (measured) steering angle Lw or a thereof derived size, like e.g. the steering speed dLw / dt. The roll size W includes e.g. the wheel-up forces, one Compression travel, vertical acceleration or roll angle, or derived variables, such as e.g. the change of the compression travel or the roll rate (change of roll angle).

The fuzzy information processing 8th is able to evaluate both a static and a dynamic relationship between a steering and a roll size W and to determine therefrom a tilt indicator K1, which indicates the tendency to tilt or the roll stability of the vehicle. In a stationary consideration of a driving situation, for example, the relationship between the steering angle and a static roll size W, such as the compression travel is evaluated and estimated a tendency to tilt. In a dynamic consideration, for example, the relationship between the steering speed and a dynamic roll size W, such as the roll rate, evaluated.

The block 8th includes fuzzy information processing, with which the relationship between the steering and Wankgröße mapped and from the combination of the individual sizes, the tendency to tilt or roll stability of the vehicle is estimated. As part of the fuzzy estimation within block 8th For example, a finite set of linguistic values to which fuzzy sets are assigned are defined on the basis amounts of a steering amount Lw and a roll size W. Together with the rule base, which models the relationship between individual linguistic values of the steering variable and the roll size, they represent the expert knowledge about the relationship between driver specification and roll dynamics depending on the center of gravity.

With the aid of the fuzzy logic processing steps known as "fuzzification" and "inference", the steering and the roll size are mapped to the linguistic variable "change in the center of gravity". The base set of these variables consists eg of the linguistic values (compared to normal loading) "unchanged", "slightly increased" and "greatly increased". By defuzzification one finally obtains the tilt indicator K1, for example in the interval [0... 1], which is a measure of the current tilt tendency of the vehicle. The tilt indicator K1 can, for example, values between 0: center of gravity unchanged, ie, normal tendency to tilt, and 1: center of gravity greatly increased, ie high tendency to tilt accept. Instead of mapping the tilt tendency to a continuous Basic set is also the classification into several discrete classes imaginable ("fuzzy classification").

Next purely static or dynamic consideration may additionally be e.g. the dynamic change a roll size W in a stationary one Driving situation are evaluated. In a stationary cornering shows a vehicle depending on the load condition or condition of the suspension a different vibration behavior about the longitudinal axis. The tilt tendency or roll stability of the vehicle can thus also by evaluation of the amplitude and / or frequency of the oscillation a roll size at fixed Estimated steering angle become.

The resulting tilt indicator K1 is now used to provide characteristics or magnitudes of the tilt stabilization algorithm 5 or to modify the strength of a stabilization engagement according to the tilt tendency. For this purpose, for example, the starting threshold of the algorithm, the permissible control deviation of a controlled variable, such as a wheel slip, or an internally calculated manipulated variable can be changed.

Optional can also the indicator size S depending be calculated from the tilting tendency. In addition, the driver a increased Tilt tendency and thus an increased Danger of tipping also be displayed, such. by means of a signal lamp in the instrument cluster.

4 shows an embodiment of an algorithm for estimating the tilt indicator K1 by means of fuzzy information processing 8th , The estimation method is performed only in given favorable driving situations, ie those situations that have a high significance for the estimation. For this purpose, the fuzzy algorithm 8th given driving dynamics variables G supplied by means of which the driving situation can be assessed. If the driving dynamics parameters G, such as a lateral acceleration or a steering speed satisfy at least one predetermined condition, the fuzzy algorithm is fulfilled 8th activated or deactivated.

In addition, a confidence variable V is generated which determines the quality of the estimate and thus the reliability of the tilt indicator 2 rated. The confidence variable V can, for example, take into account the number of learning processes and / or the duration during a journey.

The one of fuzzy information processing 8th generated tilt indicator K2 and the confidence variable V are then by means of a map 11 linked together. In terms of quality, low values of the confidence variable V (eg V = 0) produce high values for the resulting tilt indicator K3 (ie high risk of tilting) and high values of the confidence variable V (eg V = 1) produce a tilt indicator with K3 = K2 , Depending on the quality of the estimate is that of the fuzzy information processing 8th So determined Kippindikator K2 so either maintained, ie K3 = K2, or increased towards more critical values.

The tilt indicator K3 finally becomes an initialization and filter unit 12 fed. The unit 12 is set up in such a way that, after each restart of the vehicle, it outputs a starting value for the tilt indicator K1, which for safety's sake has a relatively high value, such as K1 = 1. This value thus causes a sensitive adjustment of the stabilization algorithm 5 , While driving, the tilt indicator K1 is reduced if necessary.

The unit 12 also serves to filter the estimated values K3 determined during a journey and to base the resulting value K1 on the tilt stabilization. The filtering is preferably performed as a maximum of all estimated values K3 over time or as a moving average over a certain number of estimated values.

The unit 12 is also set up so that for longer trips without sufficient learning phases, such as highway driving without curves, the tilt indicator K1 is increased to a value that represents a higher tendency to tilt and thus to a more sensitive control of the stabilization algorithm 5 leads. The unit 12 is also activated or deactivated as a function of predetermined driving dynamics parameters G.

The The arrangement described above allows a particularly accurate and reliable estimate of Tilting a vehicle by both a static and a a dynamic consideration of the relationship between a steering and a roll size.

1

control unit

2

ESP sensor

3

actuators

4

function to form an indicator size

5

rollover stabilization

6

Wankgrößen sensors

7

signal processing and monitoring

8th

Fuzzy information processing

9

braking system

10

engine management

11

map

12

initialization and filter unit

ay

lateral acceleration

/ Dt day

modification the lateral acceleration

P

factors

lw

steering variable

W

roll variable

K1, K2, K3

tilt indicators

S

indicator size

Claims (11)

Method for tilt stabilization of a vehicle in critical driving situations, in which different driving state variables (ay, day / dt, P) are detected by means of a sensor system (a) 2 . 6 ) and a tilt stabilization algorithm ( 4 . 5 ) in a tilt-critical situation by means of an actuator ( 3 . 9 . 10 is engaged in the driving operation to stabilize the vehicle, characterized in that from the relationship between a steering amount (Lw) and a roll size (W) information about the tendency to tilt (K1) of the vehicle is estimated, which takes into account in the context of a tilt stabilization becomes. A method according to claim 1, characterized in that an indicator variable (S) by means of which a stabilization intervention is enabled or disabled, or a characteristic property or magnitude of the tilt stabilization algorithm ( 4 . 5 ) is determined as a function of the tilt tendency (K1). Method according to claim 1, characterized in that that the steering size is one Steering angle (Lw) or a steering speed (dLw / dt) includes. Method according to claim 1, characterized in that that the roll size (W), the wheelwright forces, the compression travel, the vertical acceleration or the roll angle, or derived quantities, such as e.g. the roll rate. According to one of the preceding claims, characterized in that a rise threshold of the tilt stabilization algorithm ( 4 . 5 ), a control deviation or a manipulated variable of the algorithm ( 5 ) is changed as a function of the tilt tendency (K1). Method according to claim 1, characterized in that that from the steering size (Lw) and the roll size (W) Tilt indicator (K1) is determined, the tilt tendency of the vehicle displays. A method according to claim 5, characterized in that the tilt indicator (K1) by means of fuzzy information processing ( 8th ) is determined. Method according to claim 7, characterized in that the tilt indicator (K3) is evaluated with a weighting function (V) that is the quality of the estimate of the tilt indicator (K3). Vehicle dynamics control system for tilt stabilization of a vehicle in critical driving situations, comprising a control device ( 1 ) in which a tilt stabilization algorithm ( 4 . 5 ), a sensor system ( 2 ) for detecting current actual values (ay, day / dt, P) of the control and an actuator ( 3 ) for performing a stabilization intervention, characterized in that a sensor system ( 6 ) for determining a roll size (W) and a sensor system ( 2 ) for determining a steering variable (Lw), and a device ( 8th ) is provided, which is estimated from the steering and the roll size (W) a tendency to tilt (K1) of the vehicle, which is taken into account in the context of a tilt stabilization. Vehicle dynamics control system according to claim 9, characterized in that the control unit ( 1 ) an indicator quantity (S), by means of which a stabilization intervention is enabled or disabled, or a characteristic property or magnitude of the tilt stabilization algorithm ( 4 . 5 ) is determined as a function of the tilt tendency (K1). Vehicle dynamics control system according to claim 9 or 10, characterized in that the sensors ( 6 ) for determining a roll size (W) comprises a roll rate sensor.