EP0869890A1 - Method of improving the control behaviour of an antilocking system - Google Patents

Method of improving the control behaviour of an antilocking system

Info

Publication number
EP0869890A1
EP0869890A1 EP96934741A EP96934741A EP0869890A1 EP 0869890 A1 EP0869890 A1 EP 0869890A1 EP 96934741 A EP96934741 A EP 96934741A EP 96934741 A EP96934741 A EP 96934741A EP 0869890 A1 EP0869890 A1 EP 0869890A1
Authority
EP
European Patent Office
Prior art keywords
acceleration
wheels
pressure reduction
wheel
value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP96934741A
Other languages
German (de)
French (fr)
Inventor
Ivica Batistic
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Teves AG and Co OHG
Original Assignee
ITT Automotive Europe GmbH
Alfred Teves GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ITT Automotive Europe GmbH, Alfred Teves GmbH filed Critical ITT Automotive Europe GmbH
Publication of EP0869890A1 publication Critical patent/EP0869890A1/en
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
    • B60T8/1763—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to the coefficient of friction between the wheels and the ground surface
    • B60T8/17636—Microprocessor-based systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2210/00—Detection or estimation of road or environment conditions; Detection or estimation of road shapes
    • B60T2210/10—Detection or estimation of road conditions
    • B60T2210/12—Friction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2210/00—Detection or estimation of road or environment conditions; Detection or estimation of road shapes
    • B60T2210/10—Detection or estimation of road conditions
    • B60T2210/12—Friction
    • B60T2210/124—Roads with different friction levels

Definitions

  • the invention relates to a method for improving the control behavior of an anti-lock braking system (ABS), in which the rotational behavior of the vehicle wheels is measured and for determining the slip, the wheel deceleration and acceleration and other control variables, for estimating the instantaneous coefficient of friction between the wheels and the roadway and for generating brake pressure control signals is evaluated.
  • ABS anti-lock braking system
  • Electronically controlled anti-lock braking systems are now part of the standard equipment of middle and upper class motor vehicles. There are different systems. In the vast majority of cases, the most important input and control variables of the anti-lock braking system are obtained with the aid of wheel sensors, which record the turning behavior of the individual vehicle wheels and pass them on to the electronics for evaluation. Brake pressure control signals are then calculated in the so-called controller, which contains the electronics, and are passed on to actuators for modulating the brake pressure or brake pressure control; in most cases these are electrically controllable hydraulic valves.
  • the instantaneous coefficient of friction or coefficient of friction between the vehicle grips and the road is an important variable for the anti-lock control, which the electronics approximately determines by measuring and logically linking the turning behavior of the individual wheels according to predetermined criteria and algorithms.
  • Information about the coefficient of friction can be found e.g. B. gain over the accumulated pressure reduction time during a control phase or instability of a wheel.
  • B. gain over the accumulated pressure reduction time during a control phase or instability of a wheel.
  • the object of the present invention is to develop a method which, in the case of such an electronic anti-lock braking system, enables a quick and reliable estimate of the instantaneous coefficient of friction or coefficient of friction between the wheel and the road. In particular, this involves the detection or confirmation of situations with a low coefficient of friction.
  • the increase in pressure reduction in this situation ensures that the non-driven vehicle wheels accelerate almost unhindered or braked and are thus able to provide reliable information about the actual vehicle speed. In this way, a "descender" which would result in a faulty vehicle reference speed — that is, as is known, the reference speed obtained by logically linking the individual wheel speed signals — would certainly be prevented. If the subsequent re-acceleration of the wheel is higher than the value that is plausible for the low friction coefficient, the assumption or logical conclusion that this is a situation with a low friction coefficient is revised and the wheel pressure on the analyzed (non-driven) wheel if a locking tendency occurs, degraded pulsed in the usual way.
  • a value between 1.2 and 2.5 g, in particular between 1.5 and 1.8 g, can be favorable for the limit value of the filtered maximum acceleration.
  • a time period between 50 and 100 ms, in particular a time period of approximately 80 ms, is expedient as the critical duration for the positive course of the filtered acceleration, when the low coefficient of friction is exceeded.
  • FIG. 1 shows a schematically simplified block diagram of the most important components of a circuit arrangement for carrying out the method according to the invention
  • FIG. 2 shows a flow chart to illustrate the course of the individual decision steps within the scope of the method according to the invention and 3 the diagram shows the speed curve of a wheel, the associated acceleration and filtered acceleration, and the time recording when the method according to the invention is carried out.
  • FIG. 1 An electronic circuit arrangement for processing the input signals of an anti-lock braking system and for generating brake pressure control signals is shown in FIG. 1.
  • the input signals of the control system are obtained with the help of wheel sensors SI to S4.
  • signals or data are derived from the information supplied by the sensors, which represent the speeds of the individual vehicle wheels vj-v 4 .
  • an evaluation circuit 2 the deceleration and acceleration a ⁇ -a 4 of the individual wheels, the changes over time in these variables (a j -ä 4 ) and the wheel slip ⁇ 1 - ⁇ 4 are calculated from these speed signals or data .
  • a vehicle reference speed v REF approximately corresponding to the vehicle speed is required as a reference variable for this slip calculation, which is determined in a circuit 3 by logically combining the individual wheel speed signals Vj-v 4 .
  • the evaluation circuit 2 depending on the embodiment of the control electronics, further signals dependent on the rotational behavior of the individual wheels, e.g. B. peak values, mean values, etc. are derived.
  • ABS logic circuit block 4 the extensive hardwired or programmed circuits contains, gel algorithms brake pressure control signals are predetermined based on Re "obtained which are supplied to a switch block 6 via a valve control 5, the brake pressure actuators, z. B. electromagnetically controllable Hydraulic valves, contains.
  • the ABS logic 4 in many cases contains one or more complete microcomputers or microcontrollers for processing the input data and for carrying out monitoring functions.
  • the valve block 6 can contain, for example, electrically controllable inlet and outlet valves assigned to the individual regulated wheels, with which the brake pressure in the individual wheel brakes can be adjusted to the calculated value.
  • the circuit arrangement according to FIG. 1 contains an additional circuit 7, which according to the invention is used to analyze the re-acceleration or the re-acceleration behavior of the non-driven vehicle wheels - in this case wheels 1 and 2.
  • the deceleration and acceleration signals aj, a 2 obtained with the aid of the evaluation circuit 2 and containing the required input information for the additional circuit 7 are therefore supplied to the additional circuit 7 via connecting lines 1, 1, 2 .
  • these deceleration or acceleration signals aj ... a 4 represent the first time derivative of the wheel speed v j ... v 4.
  • the ge ⁇ filtered speed signals a F3 , a F4 formed in the evaluation circuit 2 or - as in the representation chosen here - in the additional circuit 7.
  • the duration T F of the positive course of the filtered acceleration a F ⁇ , a F2 also required for the method according to the invention is likewise determined in the additional circuit 7.
  • FIG. 1 symbolically represents circuits and / or program blocks with which further ABS Functions and evaluation methods of the input information are implemented. It is namely expedient to evaluate, monitor and secure the information obtained by evaluating the wheel sensor signals according to different criteria in order to detect the very different situations to which the control system must respond in a suitable manner.
  • the data processing in the ABS logic 4 is adapted to the knowledge obtained with the circuit 8 or to the special conditions.
  • the operation of the additional circuit 7 required according to the invention is illustrated by the flow chart according to FIG. 2.
  • the following function is carried out by programming or logical linking with the aid of the additional circuit 7: after the START of this special function, the acceleration signals originating from the non-driven wheels are first determined in '9'; In the embodiment according to FIG. 1, this selection is made by the exclusive connection of the additional circuit 7 via the lines I 1 / I 2 to the non-driven vehicle wheels.
  • a branch 10 according to FIG. 2 first of all for a wheel, here for the left front wheel 'VL', ascertained whether the maximum value of the re-acceleration a ⁇ in a re-acceleration phase after a previous pressure reduction reaches a limit value a G.
  • the exemplary embodiment of the invention shown is a circuit arrangement for a vehicle with rear-wheel drive, which is why the front wheels VL, VR are the ones that are analyzed by the method according to the invention.
  • the decision steps 13, 14 and 15 correspond entirely to the steps 10 to 12 explained.
  • the conditions mentioned must be met for both non-driven wheels in order to have a low friction (at) value situation or a criterion for a program step 16 to recognize such a situation (suspected low friction coefficient).
  • a permanent pressure reduction is carried out in a step 17 until the wheel re-acceleration occurs in the subsequent control phase, i. H. when the wheel starts to become unstable. 2 - begins anew.
  • the method according to the invention therefore only comes into effect if predetermined limit values are observed or exceeded on both non-driven wheels.
  • a ma-- the wheel acceleration a has a
  • a Fmax of the filtered wheel acceleration a F has a limit between 1.2 and 2.5 g
  • the minimum value should be between 50 and 100 ms; in the particular embodiment, this minimum value was set at about 80 ms.
  • the curves "A" to "D” show the speed profile v R of a non-driven front wheel, the associated wheel acceleration A, the associated filtered acceleration a F and the time recording, e.g. B. with the aid of a correspondingly controlled counter or an integrator, detected and displayed in a situation in which the method according to the invention affects the control and leads to the improvement of the control.
  • Anti-lock control starts.
  • the temporal change in the wheel speed v R namely the deceleration and acceleration a, reaches a maximum value a in the re-acceleration phase at time t x . max (see Fig. 3B).
  • the filtered wheel deceleration and re-acceleration a r naturally reaches the maximum value - only the re-acceleration after the first instability of the wheel is of interest here
  • the duration of the positive course of the filtered acceleration reaches or exceeds a time limit value T G.
  • the maximum acceleration values a ma-- and a F ⁇ na-- are below the specified limit values a G and a FG .
  • the duration of the positive half wave T is above the limit value T G. Since the conditions for both non-driven wheels are fulfilled, it is concluded, as already explained with reference to FIG. 2, that a situation with "low friction (at) value" is inferred from this and an increased or even permanent pressure reduction in the following Instability phase, which begins at time t 4 in the example according to FIG. 3.
  • the analysis according to the invention ensures that the current coefficient of friction, and in particular a low coefficient of friction, is detected particularly reliably, quickly and reliably.
  • the detection of the low-friction (at) value situation is thus already possible through the wheel course in the first control phase by evaluating the re-acceleration of the non-driven wheels.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Regulating Braking Force (AREA)

Abstract

In order to improve the control behaviour of an antilocking system, a rapid reliable detection of a reduced friction travelling situation is carried out. For that purpose, the re-acceleration of the non-driven wheels following brake pressure reduction during an adjustment is analysed and the presence of a low friction value coefficient detected if in the re-acceleration phase the maximum re-acceleration (amax) of both non-driven wheels remains below a predetermined threshold (aG) while simultaneously the maximum filtered acceleration (aFmax) remains below a defined threshold (aFG) and if the duration (T) of the positive changes in the filtered acceleration (aF) in this phase exceeds a predetermined time threshold (TG). If these conditions are met, the brake pressure reduction in the subsequent instability phase of these wheels is increased, e.g. by permanent actuation of the pressure reduction valves.

Description

Verfahren zur Verbesserung des Regelverhaltens eines ABSProcess for improving the control behavior of an ABS
Die Erfindung bezieht sich auf ein Verfahren zur Ver¬ besserung des Regelverhaltens eines Antiblockiersystems (ABS), bei dem das Drehverhalten der Fahrzeugräder gemessen und zur Ermittlung des Schlupfes, der Radverzögerung und - beschleunigung und weiterer Regelgrößen, zur Abschätzung des momentanen Reibbeiwertes zwischen den Rädern und der Fahr¬ bahn und zur Erzeugung von Bremsdruck-Steuersignalen ausge¬ wertet wird.The invention relates to a method for improving the control behavior of an anti-lock braking system (ABS), in which the rotational behavior of the vehicle wheels is measured and for determining the slip, the wheel deceleration and acceleration and other control variables, for estimating the instantaneous coefficient of friction between the wheels and the roadway and for generating brake pressure control signals is evaluated.
Elektronisch geregelte Antiblockiersysteme zählen mittler¬ weile zu den Standardausrüstungen von Kraftfahrzeugen der mittleren und gehobenen Klasse. Es gibt unterschiedliche Sy¬ steme. In den allermeisten Fällen werden die wichtigsten Eingangs- und Regelgrößen des Antiblockiersystems mit Hilfe von Radsensoren gewonnen, die das Drehverhalten der einzel¬ nen Fahrzeugräder erfassen und zur Auswertung an die Elek¬ tronik weiterleiten. In dem sog. Regler, der die Elektronik enthält, werden dann Bremsdruck-Steuersignale errechnet, die zur Modulation des Bremsdrucks oder Bremsdruckregelung an Aktuatoren weitergeleitet werden; dabei handelt es sich in den meisten Fällen um elektrisch steuerbare Hydraulikventi¬ le.Electronically controlled anti-lock braking systems are now part of the standard equipment of middle and upper class motor vehicles. There are different systems. In the vast majority of cases, the most important input and control variables of the anti-lock braking system are obtained with the aid of wheel sensors, which record the turning behavior of the individual vehicle wheels and pass them on to the electronics for evaluation. Brake pressure control signals are then calculated in the so-called controller, which contains the electronics, and are passed on to actuators for modulating the brake pressure or brake pressure control; in most cases these are electrically controllable hydraulic valves.
Das Erkennen der tatsächlichen Regelungssituation aus den Informationen, die die Radsensoren liefern, und das folge¬ richtige Steuern des Bremsdruckes zur Blockierschutz¬ regelung, ist bekanntlich immer dann schwierig, wenn die In- terpretation des Drehverhaltens der Räder keine eindeutige Aussage über die momentane Straßensituation und das Fahr¬ zeugverhalten zuläßt.Recognizing the actual control situation from the information provided by the wheel sensors and the subsequent correct control of the brake pressure for anti-lock control is known to be always difficult when the in- interpretation of the turning behavior of the wheels does not allow a clear statement about the current road situation and the vehicle behavior.
Der momentane Reibwert oder Reibbeiwert zwischen den Fahr¬ zeugreifen und der Straße ist eine für die Blockierschutz¬ regelung wichtige Größe, die die Elektronik durch Messen und logische Verknüpfung des Drehverhaltens der einzelnen Räder nach vorgegebenen Kriterien und Algorithmen näherungsweise ermittelt. Informationen über den Reibbeiwert lassen sich z. B. über die akkumulierte Druckabbauzeit während einer Re¬ gelphase bzw. Instabilität eines Rades gewinnen. In bestimm¬ ten Situationen, nämlich bei geringer Differenz zwischen Antriebs- und Bremsmoment - als Folge eines vorsichtigen Anbremsens auf glatter Fahrbahn etc. - können sich jedoch "schleichende" Radverläufe ergeben, welche die Gefahr eines sog. "Abseilens", d.h. Unterlaufen aller Erkennungskriterien für eine Radinstabilität, mit sich bringen. Die Auswertelo¬ gik könnte also in solchen Situationen gewissermaßen "ir¬ regeführt" werden. Das Verhalten der Räder muß daher nach verschiedenen Prinzipien und Kriterien analysiert werden, um ein Fehlverhalten der Regelung auszuschließen.The instantaneous coefficient of friction or coefficient of friction between the vehicle grips and the road is an important variable for the anti-lock control, which the electronics approximately determines by measuring and logically linking the turning behavior of the individual wheels according to predetermined criteria and algorithms. Information about the coefficient of friction can be found e.g. B. gain over the accumulated pressure reduction time during a control phase or instability of a wheel. In certain situations, namely when there is a small difference between the drive and braking torque - as a result of careful braking on slippery roads, etc. - "creeping" wheel profiles can result, which increases the risk of so-called "abseiling", i.e. Undermine all detection criteria for a wheel instability. The evaluation logic could thus be "misled" to a certain extent in such situations. The behavior of the wheels must therefore be analyzed according to various principles and criteria in order to rule out any misconduct in the regulation.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Verfahren zu entwickeln, das bei einem solchen elektroni¬ schen Antiblockiersystem eine schnelle und zuverlässige Ab¬ schätzung des momentanen Reibwerts bzw. Reibbeiwerts zwi¬ schen Rad und Straße ermöglicht. Insbesondere geht es dabei um die Erkennung oder Bestätigung von Situationen mit nied¬ rigem Reibbeiwert.The object of the present invention is to develop a method which, in the case of such an electronic anti-lock braking system, enables a quick and reliable estimate of the instantaneous coefficient of friction or coefficient of friction between the wheel and the road. In particular, this involves the detection or confirmation of situations with a low coefficient of friction.
Es hat sich herausgestellt, daß diese Aufgabe mit dem im beigefügten Anspruch 1 beschriebenen Verfahren gelöst werden kann. Die Besonderheiten dieses Verfahrens bestehen darin, daß zum Erkennen eines Regelungsvorgangs auf niedrigem Reib¬ wert oder Überprüfen einer auf andere Weise von der Elek¬ tronik ermittelten Niedrigreibwert-Fahrsituation die Wie¬ derbeschleunigung der nichtangetriebenen Räder im Anschluß an einen regelungsbedingten Bremsdruckabbau an diesen Rädern analysiert wird und daß es als Fahrsituation auf niedrigem Reib(bei)wert zwischen Rad und Straße bewertet wird, wenn in der Wiederbeschleunigungsphase gleichzeitig die maximale Wiederbeschleunigung der beiden analysierten Räder unter einem spezifischen, vorgegebenen Grenzwert und die maximale gefilterte Beschleunigung dieser Räder unter einem anderen spezifischen, ebenfalls vorgegebenen Grenzwert liegen und wenn die Dauer des positiven Verlaufs der gefilterten Be¬ schleunigung in dieser Phase eine vorgegebene Zeitspanne überschreitet, und daß in dieser Niedrigreibbeiwert-Situa- tion der Bremsdruckabbau an diesen Rädern in der folgenden Instabilitätsphase erhöht wird. Diese Erhöhung kann zweck¬ mäßigerweise, wenn es sich um ein Regelungssystem mit ge¬ pulster Ansteuerung der Druckabbauventile handelt - dies ist eine übliche Methode -, durch einen ungepulsten Druckabbau erzielt werden.It has been found that this object can be achieved with the method described in appended claim 1. The peculiarities of this procedure are that in order to identify a control process with a low coefficient of friction or to check a low-friction value driving situation determined in another way by the electronics, the re-acceleration of the non-driven wheels following a control-related reduction in brake pressure on these wheels is analyzed and that it is a driving situation with low Friction (at) value between wheel and road is assessed if, in the re-acceleration phase, the maximum re-acceleration of the two analyzed wheels is simultaneously below a specific, specified limit value and the maximum filtered acceleration of these wheels is below a specific, also specified limit value and if the duration of the positive course of the filtered acceleration in this phase exceeds a predetermined period of time, and that in this low coefficient of friction situation the brake pressure reduction on these wheels is increased in the following instability phase. This increase can expediently be achieved by an unpulsed pressure reduction, if it is a control system with pulsed activation of the pressure reduction valves - this is a common method.
Durch die erfindungsgemäß vorgesehene Erhöhung des Druck¬ abbaus in dieser Situation wird erreicht, daß die nnichtan- getriebenn Fahrzeugräder nahezu ungehindert bzw. ungebremst beschleunigen und dadurch in der Lage sind, eine zu¬ verlässige Information über die tatsächliche Fahrzeug¬ geschwindigkeit abzugeben. Auf diese Weise wird einem "Ab- seiler", der eine fehlerhafte Fahrzeugreferenzgeschwindig¬ keit - das ist bekanntlich die durch logische Verknüpfung der einzelnen Radgeschwindigkeitssignale gewonnene Bezugs¬ geschwindigkeit - zur Folge hätte mit Sicherheit vorgebeugt. Ist die anschließende Wiederbeschleunigung des Rades höher als der für den Niedrigreibbeiwert plausible Wert, wird die Annahme bzw. logische Schlußfolgerung, daß es sich um eine Situation mit Niedrigreibbeiwert handelt, revidiert und der Raddruck an dem analysierten (nichtangetriebenen) Rad, wenn eine Blockiertendenz auftritt, in der gewohnten Weise ge¬ pulst abgebaut.The increase in pressure reduction in this situation, which is provided according to the invention, ensures that the non-driven vehicle wheels accelerate almost unhindered or braked and are thus able to provide reliable information about the actual vehicle speed. In this way, a "descender" which would result in a faulty vehicle reference speed — that is, as is known, the reference speed obtained by logically linking the individual wheel speed signals — would certainly be prevented. If the subsequent re-acceleration of the wheel is higher than the value that is plausible for the low friction coefficient, the assumption or logical conclusion that this is a situation with a low friction coefficient is revised and the wheel pressure on the analyzed (non-driven) wheel if a locking tendency occurs, degraded pulsed in the usual way.
Nach einem vorteilhaften Ausführungsbeispiel der Erfindung wird der Grenzwert für die maximale Beschleunigung auf einen Wert in der Größenordnung zwischen 2,5 und 4g, z. B. auf einen Wert von etwa 3g vorgegeben. Für den Grenzwert der gefilterten maximalen Beschleunigung kann ein Wert zwischen 1,2 und 2,5g, insbesondere zwischen 1,5 und 1,8g, günstig sein. Als kritische Dauer für den positiven Verlauf der ge¬ filterten Beschleunigung, bei deren Überschreitung Niedri¬ greibbeiwert erkannt wird, iεt eine Zeitspanne zwischen 50 und 100 ms, insbesondere eine Zeitspanne von etwa 80 ms zweckmäßig.According to an advantageous embodiment of the invention, the limit value for the maximum acceleration to a value in the range between 2.5 and 4g, z. B. predetermined to a value of about 3g. A value between 1.2 and 2.5 g, in particular between 1.5 and 1.8 g, can be favorable for the limit value of the filtered maximum acceleration. A time period between 50 and 100 ms, in particular a time period of approximately 80 ms, is expedient as the critical duration for the positive course of the filtered acceleration, when the low coefficient of friction is exceeded.
Weitere Vorteile, Merkmale und Anwendungsmöglichkeiten der Erfindung gehen aus der folgenden Beschreibung eines Aus¬ führungsbeispiels anhand der beigefügten Abbildungen hervor.Further advantages, features and possible uses of the invention will become apparent from the following description of an exemplary embodiment with reference to the attached figures.
Es zeigenShow it
Fig. 1 in schematisch vereinfachter Blockdarstellung die wichtigsten Komponenten einer Schaltungsanordnung zur Durchführung des Verfahrens nach der Erfindung,1 shows a schematically simplified block diagram of the most important components of a circuit arrangement for carrying out the method according to the invention,
Fig. 2 ein Flow-Chart zur Veranschaulichung des Ablaufs der einzelnen Entscheidungsschritte im Rahmen des erfin¬ dungsgemäßen Verfahrens und Fig. 3 im Diagramm den Geschwindigkeitsverlauf eines Rades, der zugehörigen Beschleunigung und gefilterten Be¬ schleunigung sowie die Zeiterfassung bei Durchfüh¬ rung des Verfahrens nach der Erfindung.2 shows a flow chart to illustrate the course of the individual decision steps within the scope of the method according to the invention and 3 the diagram shows the speed curve of a wheel, the associated acceleration and filtered acceleration, and the time recording when the method according to the invention is carried out.
Eine elektronische Schaltungsanordnung zur Verarbeitung der Eingangssignale eines Antiblockier-Systems und zur Erzeugung von Bremsdruck-Steuersignalen ist in Fig. 1 wiedergegeben. Die Eingangssignale des Regelungssystems werden mit Hilfe von Radsensoren SI bis S4 gewonnen. In einer Aufbereitungs- schaltung 1 werden aus den von den Sensoren gelieferten In¬ formationen Signale oder Daten abgeleitet, die die Geschwin¬ digkeiten der einzelnen Fahrzeugräder vj - v4 wiedergeben. In einer Auswerteschaltung 2 werden aus diesen Geschwindig¬ keitssignalen oder -daten u.a. die Verzögerung und Beschleu¬ nigung aλ - a4 der einzelnen Räder, die zeitlichen Änderungen dieser Größen (aj - ä4), der Radschlupf λ1 - λ4 errechnet.An electronic circuit arrangement for processing the input signals of an anti-lock braking system and for generating brake pressure control signals is shown in FIG. 1. The input signals of the control system are obtained with the help of wheel sensors SI to S4. In a processing circuit 1, signals or data are derived from the information supplied by the sensors, which represent the speeds of the individual vehicle wheels vj-v 4 . In an evaluation circuit 2, the deceleration and acceleration a λ -a 4 of the individual wheels, the changes over time in these variables (a j -ä 4 ) and the wheel slip λ 1 - λ 4 are calculated from these speed signals or data .
Als Bezugsgröße für diese Schlupfberechnung wird eine näherungsweise der Fahrzeuggeschwindigkeit entsprechende Fahrzeugreferenzgeschwindigkeit vREF benötigt, die in einem Schaltkreis 3 durch logische Verknüpfung der einzelnen Rad¬ geschwindigkeitssignale Vj - v4 ermittelt wird. In der Aus¬ wertungsschaltung 2 können je nach Ausführungsform der Re¬ gelelektronik noch weitere von dem Drehverhalten der ein¬ zelnen Räder abhängige Signale, z. B. Spitzenwerte, Mittel¬ werte usw. abgeleitet werden.A vehicle reference speed v REF approximately corresponding to the vehicle speed is required as a reference variable for this slip calculation, which is determined in a circuit 3 by logically combining the individual wheel speed signals Vj-v 4 . In the evaluation circuit 2, depending on the embodiment of the control electronics, further signals dependent on the rotational behavior of the individual wheels, e.g. B. peak values, mean values, etc. are derived.
In einem symbolisch als ABS-Logik dargestellten Schaltblock 4, der umfangreiche, festverdrahtete oder programmgesteuerte Schaltungen enthält, werden auf Basis vorgegebener Re"gel- algorithmen Bremsdrucksteuersignale gewonnen, die über eine Ventilansteuerung 5 einem Schaltblock 6 zugeführt werden, der Bremsdruckaktuatoren, z. B. elektromagnetisch steuerbare Hydraulikventile, enthält. Bei heutigen Systemen enthält die ABS-Logik 4 in vielen Fällen einen oder mehrere komplette Mikrocomputer oder MikroController zur Verarbeitung der Ein¬ gangsdaten und zur Durchführung von Überwachungsfunktionen.In a symbolically represented as ABS logic circuit block 4, the extensive hardwired or programmed circuits contains, gel algorithms brake pressure control signals are predetermined based on Re "obtained which are supplied to a switch block 6 via a valve control 5, the brake pressure actuators, z. B. electromagnetically controllable Hydraulic valves, contains. In today's systems, the ABS logic 4 in many cases contains one or more complete microcomputers or microcontrollers for processing the input data and for carrying out monitoring functions.
Der Ventilblock 6 kann beispielsweise den einzelnen geregel¬ ten Rädern zugeordnete, elektrisch steuerbare Einlaß- und Auslaßventile enthalten, mit denen sich der Bremsdruck in den einzelnen Radbremsen auf den errechneten Wert einstellen läßt.The valve block 6 can contain, for example, electrically controllable inlet and outlet valves assigned to the individual regulated wheels, with which the brake pressure in the individual wheel brakes can be adjusted to the calculated value.
Zur Durchführung des erfindungsgemäßen Verfahrens enthält die Schaltungsanordnung nach Fig. 1 eine Zusatzschaltung 7, die erfindungsgemäß zur Analyse der Wiederbeschleunigung bzw. des Wiederbeschleunigungsverhaltens der nicht angetrie¬ benen Fahrzeugräder - das seien hier die Räder 1 und 2 - herangezogen wird. Über Anschlußleitungen lχ,l2 werden daher der Zusatzschaltung 7 die mit Hilfe der Auswertungsschaltung 2 gewonnenen Verzögerungs- und Beschleunigungssignale aj,a2, die die benötigen Eingangsinformationen für die Zusatzschal¬ tung 7 enthalten, zugeführt. Diese Verzögerungs- oder Be¬ schleunigungssignale aj ... a4 stellen bekanntlich die erste zeitliche Ableitung der Radgeschwindigkeit vj ... v4 dar. In der Auswerteschaltung 2 oder - wie in der hier gewählten Darstellungsweise - in der Zusatzschaltung 7 werden die ge¬ filterten Geschwindigkeitssignale aF3,aF4 gebildet. Die au¬ ßerdem für das erfindungsgemäße Verfahren benötigte Dauer TF des positiven Verlaufs der gefilterten Beschleunigung aFι,aF2 wird ebenfalls in der Zusatzschaltung 7 ermittelt.To carry out the method according to the invention, the circuit arrangement according to FIG. 1 contains an additional circuit 7, which according to the invention is used to analyze the re-acceleration or the re-acceleration behavior of the non-driven vehicle wheels - in this case wheels 1 and 2. The deceleration and acceleration signals aj, a 2 obtained with the aid of the evaluation circuit 2 and containing the required input information for the additional circuit 7 are therefore supplied to the additional circuit 7 via connecting lines 1, 1, 2 . As is known, these deceleration or acceleration signals aj ... a 4 represent the first time derivative of the wheel speed v j ... v 4. In the evaluation circuit 2 or - as in the representation chosen here - in the additional circuit 7, the ge ¬ filtered speed signals a F3 , a F4 formed. The duration T F of the positive course of the filtered acceleration a F ι, a F2 also required for the method according to the invention is likewise determined in the additional circuit 7.
Schließlich ist in Fig. 1 noch eine weitere Zusatzschaltung 8 gestrichelt eingezeichnet, die symbolisch Schaltkreise und/oder Programmblöcke darstellt, mit denen weitere ABS- Funktionen und Auswertemethoden der Eingangsinformationen realisiert sind. Es ist nämlich zweckmäßig, die durch Aus¬ wertung der Radsensor-Signale gewonnenen Informationen nach unterschiedlichen Kriterien auszuwerten, zu überwachen und abzusichern, um den sehr unterschiedlichen Situationen, auf die die Regelung in der geeigneten Weise reagieren muß, zu erfassen. Mit Hilfe der in der nur angedeuteten Zusatzschal¬ tung 8 gewonnenen Signale wird die Datenverarbeitung in der ABS-Logik 4 den mit Hilfe der Schaltung 8 gewonnenen Er¬ kenntnissen bzw. den speziellen Bedingungen angepaßt.Finally, a further additional circuit 8 is shown in broken lines in FIG. 1, which symbolically represents circuits and / or program blocks with which further ABS Functions and evaluation methods of the input information are implemented. It is namely expedient to evaluate, monitor and secure the information obtained by evaluating the wheel sensor signals according to different criteria in order to detect the very different situations to which the control system must respond in a suitable manner. With the aid of the signals obtained in the additional circuit 8, which is only indicated, the data processing in the ABS logic 4 is adapted to the knowledge obtained with the circuit 8 or to the special conditions.
Die Arbeitsweise der erfindungsgemäß erforderlichen Zusatz¬ schaltung 7 wird durch das Flow-Chart nach Fig. 2 veran¬ schaulicht. Durch Programmierung oder logische Verknüpfung wird mit Hilfe der Zusatzschaltung 7 folgende Funktion ausgeführt: Nach dem START dieser Sonderfunktion werden als erstes in '9' die von den nichtangetriebenen Rädern stammen¬ den Beschleunigungssignale ermittelt; in dem Ausführungsbei¬ spiel nach Fig. 1 erfolgt diese Auswahl durch die aus¬ schließliche Anbindung der Zusatzschaltung 7 über die Lei¬ tungen I1/I2 an die nichtangetriebenen Fahrzeugräder.The operation of the additional circuit 7 required according to the invention is illustrated by the flow chart according to FIG. 2. The following function is carried out by programming or logical linking with the aid of the additional circuit 7: after the START of this special function, the acceleration signals originating from the non-driven wheels are first determined in '9'; In the embodiment according to FIG. 1, this selection is made by the exclusive connection of the additional circuit 7 via the lines I 1 / I 2 to the non-driven vehicle wheels.
In einer Verzweigung 10 wird dann gemäßFig. 2 zunächst für ein Rad, hier für das linke Vorderrad 'VL' , festgestellt, ob der Maximalwert der Wiederbeschleunigung a^ in einer Wie- derbeschleunigungsphase nach vorangegangenem Druckabbau einen Grenzwert aG erreicht. In dem dargestellten Aus¬ führungsbeispiel der Erfindung handelt es sich um eine Schaltungsanordnung für ein Fahrzeug mit Heckantrieb, wes¬ halb die Vorderräder VL, VR diejenigen sind, die nach- dem erfindungsgemäßen Verfahren analysiert werden. Liegen nun der Maximalwert der Wiederbeschleunigung aVL des linken Vorderrades VL unter dem vorgegebenen Grenzwert aG und der Maximalwert der gefilterten Wiederbeschleunigung aFVIι dieses Rades unter einem für die gefilterte Beschleunigung vorgegebenen Grenzwert aFG, was in einer Verzweigung 11 er¬ mittelt wird, folgt Schritt 12. Wird in "12" die Frage nach der ausreichenden Dauer TF des positiven Verlaufs der gefil¬ terten Beschleunigung "bejaht", ist also die Dauer TF größer als ein vorgegebener Grenzwert TGf schließt sich die gleicheIn a branch 10 according to FIG. 2 first of all for a wheel, here for the left front wheel 'VL', ascertained whether the maximum value of the re-acceleration a ^ in a re-acceleration phase after a previous pressure reduction reaches a limit value a G. The exemplary embodiment of the invention shown is a circuit arrangement for a vehicle with rear-wheel drive, which is why the front wheels VL, VR are the ones that are analyzed by the method according to the invention. If the maximum value of the re-acceleration a VL of the left front wheel VL is below the predetermined limit value a G and the maximum value of the filtered re-acceleration a FVIι of this wheel is below a limit value a FG which is determined for the filtered acceleration, which is determined in a branch 11 Step 12. If the answer to the sufficient duration T F of the positive course of the filtered acceleration is answered in "12", the duration T F is greater than a predetermined limit value T Gf , the same is concluded
Abfragefolge für das zweite nnichtangetrieben Rad, nämlich für das Vorderrad VR, an.Query sequence for the second non-driven wheel, namely for the front wheel VR.
Die Entscheidungsschritte 13,14 und 15 entsprechen vollends den erläuterten Schritten 10 bis 12. Die genannten Bedingun¬ gen müssen nämlich für beide nichtangetriebenen Räder er¬ füllt sein, um in einem Programmschritt 16 eine Niedrigreib(bei)wert-Situation bzw. ein Kriterium für eine solche Situation (Niedrigreibbeiwert-Verdacht) zu erkennen. Als Reaktion auf die Erkennung des Niedrigreib(bei)wertes wird in einem Schritt 17 ein permanenter Druckabbau bis zum Eintritt der Radwiederbeschleunigung in der anschließenden Regelphase, d. h. bei dem anschließenden Instabilwerden Hochlaufen des Rades, herbeigeführt. Die Abfrageprozedur dargestellt in Fig. 2 - beginnt von neuem.The decision steps 13, 14 and 15 correspond entirely to the steps 10 to 12 explained. The conditions mentioned must be met for both non-driven wheels in order to have a low friction (at) value situation or a criterion for a program step 16 to recognize such a situation (suspected low friction coefficient). In response to the detection of the low friction (at) value, a permanent pressure reduction is carried out in a step 17 until the wheel re-acceleration occurs in the subsequent control phase, i. H. when the wheel starts to become unstable. 2 - begins anew.
Das erfindungsgemäße Verfahren gelangt also nur dann zur Wirkung, wenn an beiden nichtangetriebenen Rädern vorgege¬ bene Grenzwerte eingehalten bzw. überschritten werden. Für den Maximalwert ama-- der Radbeschleunigung a hat sich einThe method according to the invention therefore only comes into effect if predetermined limit values are observed or exceeded on both non-driven wheels. For the maximum value a ma-- the wheel acceleration a has a
Grenzwert zwischen 2,5 und 4g - in einem speziellen Ausfüh¬ rungsbeispiel ein Grenzwert von etwa 3g - als zweckmäßig erwiesen. Für den Maximalwert aFmax der gefilterten Radbe- schleunigung aF hat sich ein Grenzwert zwischen 1,2 und 2,5gLimit value between 2.5 and 4 g - in a special exemplary embodiment a limit value of about 3 g - has proven to be expedient. For the maximum value a Fmax of the filtered wheel acceleration a F has a limit between 1.2 and 2.5 g
- im speziellen Beispiel zwischen 1,5 und 1,8g - als beson¬ ders vorteilhaft gezeigt. Für die Zeitspanne des positiven Verlaufs der gefilterten Beschleunigung aF in dieser Phase sollte der Mindestwert zwischen 50 und 100 ms liegen; in dem speziellen Ausführungsbeispiel wurde dieser Mindestwert auf etwa 80 ms festgesetzt.- In the specific example between 1.5 and 1.8 g - shown as particularly advantageous. For the period of the positive course of the filtered acceleration a F in this phase, the minimum value should be between 50 and 100 ms; in the particular embodiment, this minimum value was set at about 80 ms.
In Fig. 3 sind in den Kurven "A" bis "D" der Geschwindig¬ keitsverlauf vR eines nichtangetriebenen Vorderrades, die zugehörige Radbeschleunigung A, die zugehörige gefilterte Beschleunigung aF und die Zeiterfassung, z. B. mit Hilfe ei¬ nes entsprechend gesteuerten Zählers oder eines Integrators, in einer Situation erfaßt und dargestellt, in der sich das erfindungsgemäße Verfahren auf die Regelung auswirkt und zur Regelungsverbesserung führt.In FIG. 3, the curves "A" to "D" show the speed profile v R of a non-driven front wheel, the associated wheel acceleration A, the associated filtered acceleration a F and the time recording, e.g. B. with the aid of a correspondingly controlled counter or an integrator, detected and displayed in a situation in which the method according to the invention affects the control and leads to the improvement of the control.
Zum Zeitpunkt t0 zeigt das nichtangetriebene Rad, dessen Ge¬ schwindigkeit mit vR bezeichnet ist, Blockiertendenz. DieAt time t 0 , the non-driven wheel, the speed of which is designated v R , shows a tendency to lock. The
Blockierschutzregelung setzt ein. Die zeitliche Änderung der Radgeschwindigkeit vR, nämlich die Verzögerung und Beschleu¬ nigung a, erreicht in der Wiederbeschleunigungsphase zum Zeitpunkt tx einen Maximalwert a.max (siehe Fig. 3B). Die ge¬ filterte Radverzögerung und Wiederbeschleunigung ar erreicht naturgemäß den Maximalwert - es interessiert hier nur die Wiederbeschleunigung nach der ersten Instabilität des RadesAnti-lock control starts. The temporal change in the wheel speed v R , namely the deceleration and acceleration a, reaches a maximum value a in the re-acceleration phase at time t x . max (see Fig. 3B). The filtered wheel deceleration and re-acceleration a r naturally reaches the maximum value - only the re-acceleration after the first instability of the wheel is of interest here
- etwas später, nämlich zum Zeitpunkt t2 (siehe Fig. 3C). Die- a little later, namely at time t 2 (see FIG. 3C). The
Dauer des positiven Verlaufs der gefilterten Beschleunigung erreicht bzw. überschreitet einen Zeit-Grenzwert TG. In demThe duration of the positive course of the filtered acceleration reaches or exceeds a time limit value T G. By doing
Beispiel nach den Diagrammen in Fig. 3 liegen die Beschleunigungs-Maximalwerte ama-- und aFιna-- unter den vorgege¬ benen Grenzwerten aG bzw. aFG. Die Dauer der positiven Halb- welle T liegt über dem Grenzwert TG. Da die Bedingungen für beide nichtangetriebenen Räder erfüllt sind, wird, wie be¬ reits anhand der Fig. 2 erläutert, daraus auf das Vorliegen einer Situation mit "Niedrigreib(bei)wert" geschlossen und eine erhöhter oder sogar permanenter Druckabbau in der fol¬ genden Instabilitätsphase, die zum Zeitpunkt t4 in dem Bei¬ spiel nach Fig. 3 einsetzt, herbeigeführt.For example, according to the diagrams in FIG. 3, the maximum acceleration values a ma-- and a Fιna-- are below the specified limit values a G and a FG . The duration of the positive half wave T is above the limit value T G. Since the conditions for both non-driven wheels are fulfilled, it is concluded, as already explained with reference to FIG. 2, that a situation with "low friction (at) value" is inferred from this and an increased or even permanent pressure reduction in the following Instability phase, which begins at time t 4 in the example according to FIG. 3.
Durch die erfindungsgemäße Analyse wird eine besonders sichere, schnelle und zuverlässige Erkennung des aktuellen Reibbeiwertes und insbesondere eines niedrigen Reibbeiwertes gewährleistet. Die Erkennung der Niedrigreib(bei)wert-Situa- tion ist dadurch schon durch den Radverlauf in der ersten Regelphase durch Auswertung der Wiederbeschleunigung der nnichtangetriebenn Räder möglich. The analysis according to the invention ensures that the current coefficient of friction, and in particular a low coefficient of friction, is detected particularly reliably, quickly and reliably. The detection of the low-friction (at) value situation is thus already possible through the wheel course in the first control phase by evaluating the re-acceleration of the non-driven wheels.

Claims

Patentansprüche claims
1. Verfahren zur Verbesserung des Regelverhaltens eines Antiblockier-Systems, bei dem das Drehverhalten der Fahrzeugräder gemessen und zur Ermittlung des Schlupfes, der Radverzögerung und -beschleunigung sowie weiterer Regelgrößen, zur Abschätzung des momentanen Reibbeiwer¬ tes zwischen den Rädern und der Fahrbahn und zur Erzeu¬ gung von Bremsdruck-Steuersignalen ausgewertet wird, dadurch gekennzeichnet, daß die Wiederbeschleunigung (a) der nichtangetriebenn Räder im Anschluß an einen rege¬ lungsbedingten Bremsdruckabbau an diesen Rädern analy¬ siert wird und daß der Reibbeiwert zwischen Rad und Straße als niedrig bewertet wird, wenn in der Wiederbe- schleunigungsphase gleichzeitig die maximale Wieüeibe- schleunigung (amax) der beiden nichtangetriebenen Räder des Fahrzeugs unter einem vorgegebenen Grenzwert (aG) und die maximale gefilterte Beschleunigung (aFmax) dieser1. A method for improving the control behavior of an anti-lock braking system, in which the turning behavior of the vehicle wheels is measured and for determining the slip, the wheel deceleration and acceleration as well as further control variables, for estimating the instantaneous coefficient of friction between the wheels and the road and for generating ¬ supply of brake pressure control signals is evaluated, characterized in that the re-acceleration (a) of the non-driven wheels following a control-related brake pressure reduction on these wheels is analyzed and that the coefficient of friction between the wheel and the road is rated as low if in the re-acceleration phase simultaneously the maximum weighing acceleration (a max ) of the two non-driven wheels of the vehicle below a predetermined limit value (a G ) and the maximum filtered acceleration (a Fmax ) of these
Räder unter einem spezifischen, vorgegebenen Grenzwert (aFG) liegen und wenn die Dauer (T) des positiven Ver¬ laufs der gefilterten Beschleunigung (aF) in dieser Phase eine vorgegebene Zeitspanne (TG) überschreitet, und daß in dieser Niedrigreibbeiwert-Situation der Bremsdruck¬ abbau an den nichtangetriebenen Rädern in der folgenden Instabilitätsphase erhöht wird.Wheels are below a specific, predetermined limit value (a FG ) and if the duration (T) of the positive course of the filtered acceleration (a F ) in this phase exceeds a predetermined time period (T G ), and that in this low coefficient of friction situation the brake pressure reduction on the non-driven wheels is increased in the following instability phase.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß bei einem Antiblockiersystem mit Regelung des Bremsdruk- kes durch Druckaufbau- und Druckabbaupulse der Brems¬ druckabbau in der Niedrigreibbeiwert-Situation durch permanente Ansteuerung des Druckabbauventils erhöht wird. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeich¬ net, daß der Grenzwert (aG)für die maximale Beschleuni¬ gung (amax) auf einen Wert in der Größenordnung zwischen2. The method according to claim 1, characterized in that in an anti-lock braking system with control of the Bremsdruk- kes by pressure build-up and pressure reduction pulses the Brems¬ pressure reduction in the low coefficient of friction situation is increased by permanent control of the pressure reduction valve. Method according to Claim 1 or 2, characterized in that the limit value (a G ) for the maximum acceleration (a max ) is between a value of the order of magnitude
2,5g und 4g, z. B. auf einen Wert von etwa 3 g festge¬ setzt wird.2.5g and 4g, e.g. B. is set to a value of about 3 g.
Verfahren nach einem oder mehreren der Ansprüche I bisMethod according to one or more of claims I to
3, dadurch gekennzeichnet, daß der Grenzwert (aFa) für die maximale gefilterte Beschleunigung (aFmax) mit 1,2g bis 2,5g, insbesondere mit 1,5 - 1,8g vorgegeben wird.3, characterized in that the limit value (a Fa ) for the maximum filtered acceleration (a Fmax ) is specified with 1.2g to 2.5g, in particular with 1.5-1.8g.
Verfahren nach einem oder mehreren der Ansprüche 1 bisMethod according to one or more of claims 1 to
4, dadurch gekennzeichnet, daß der Grenzwert (TG) für die4, characterized in that the limit value (T G ) for the
Dauer (T) des positiven Verlaufs der gefilterten Rad¬ beschleunigung (aF) auf einen Wert zwischen 50 und 100 ms, insbesondere als ein Wert von etwa 80 ms, festge¬ setzt wird. Duration (T) of the positive course of the filtered wheel acceleration (a F ) is set to a value between 50 and 100 ms, in particular as a value of approximately 80 ms.
EP96934741A 1995-12-02 1996-10-18 Method of improving the control behaviour of an antilocking system Ceased EP0869890A1 (en)

Applications Claiming Priority (3)

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DE19545012A DE19545012B4 (en) 1995-12-02 1995-12-02 Method for improving the control behavior of an ABS
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PCT/EP1996/004530 WO1997020718A1 (en) 1995-12-02 1996-10-18 Method of improving the control behaviour of an antilocking system

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