DE102007036578A1 - Method for determining a slippage of a vehicle comprises determining driving dynamics parameters and/or driving dynamics conditions for determining the vehicle stoppage and feeding to a sensor for controlling the stability or traction - Google Patents

Abstract

Method for determining a slippage of a vehicle comprises determining the driving dynamics parameters and/or the driving dynamics conditions for determining the vehicle stoppage with respect to interrupting parameters and/or interrupting conditions and feeding to a sensor for controlling the stability or traction. An independent claim is also included for a driver assistant for assisting a driver of a vehicle. Preferred Features: The steering angle is evaluated for testing the operational state of the vehicle.

Description

The The invention relates to the field of vehicle driving aids and in particular a method having the features of the preamble of claim 1 and a start assist with the features of claim 6.

at a vehicle with a traction help or a start-up assistant the service brake system is used to assist the vehicle during a assisted startup to keep on a sloping road until sufficient for starting Torque is transmitted from the drive motor to the wheels. Usually while the service brake is controlled automatically, which for standstill required braking forces generated. For a longer one Standstill is for this also brought an electric parking brake device used.

The DE 10 2005 015 062 relates to a method for determining a vehicle standstill after braking, in which an automatic continuation of this operating state to prevent the vehicle from rolling away during startup is performed. Such methods describe a traction help, with the vehicles when starting on the mountain on the service brake to be prevented from rolling back. Slipping the vehicles on the mountain when detected vehicle arrest, they are no longer controllable due to the blocked by the traction help wheels. It is therefore proposed to check the operating state of the vehicle by means of vehicle dynamics variables and / or driving dynamics states and to cancel the automatic continuation of the operating state as a function of the test result. A special regulation for stability or traction control is initiated.

From the DE 44 46 823 C1 a device for preventing the rolling away of a vehicle is known in which at a proper, ie when the parking brake, parked vehicle, a standstill of the vehicle sicherstellender brake pressure is generated when the parking brake is released. This is intended to ensure unintentional rolling away of the vehicle as long as no starting procedure has been detected or until the parking brake of the vehicle is actuated.

From the WO 92/04213 An arrangement for holding a vehicle on the mountain is known, which allows a holding aid, a so-called Hillholder function on an inclined road.

The DE 195 25 552 A1 discloses a method for holding a vehicle on an inclined road and when starting on the mountain, in which taking into account the vehicle speed and the brake pedal operation or corresponding criteria braking force is applied to one or more vehicle wheels, in particular on the wheels of an axle, ie maintained, increased and is dismantled again. The braking force is adjusted as a function of the driving situation of the vehicle.

From the DE 196 25 919 A1 is a system for controlling the braking effect in a motor vehicle, in which detects the vehicle longitudinal speed and depending on this vehicle longitudinal speed, a creep suppression mode or a Hillholder mode are activated, so as to prevent a driver unwanted movement of the vehicle.

From the DE 196 21 628 A1 also discloses a method or apparatus for controlling a brake system of a vehicle, which allows a so-called hillholder function. This hill-holder function is activated by the fact that the driver actuates the brake pedal and there is a corresponding request signal, for example from a push-button actuable by the driver or from a vehicle standstill recognition.

Facilities with hillholder functions are further from the DE 34 26 669 A1 , of the DE 35 07 330 A1 , of the EP 0 822 129 A1 and the DE 36 18 532 A1 known.

From the DE 196 11 360 A1 a device for actuating the brake system of a road vehicle is known in which in a road vehicle with automatic transmission in traffic-related downtime phases in which a gear of the transmission is engaged with the engine running, a short time after the vehicle has come to a standstill by a target braking, the service brake is automatically activated, so that the driver can cancel the brake pedal operation and the vehicle is held on a flat or sloping roadway at a standstill. This parking brake operation of the service brake system of the vehicle is canceled when the driver operates the accelerator pedal whose position is monitored by means of a switch. This device also allows a traction on the mountain.

There are a variety of conditions under which startup ( WO 99/20921 . DE 199 50 162 . DE 10063061 . DE 198 25 642 ) or activation of the start-up assistant can or should take place. In this case, a start assist solves the problem encountered when driving on an inclined road, for example on a slope, that the vehicle rolls back a little when the driver takes his foot off the brake pedal to accelerate a short time later. Out of the DE 199 50 162 A1 is a start assist known, which is manually activated by the driver via the brake pedal, and manages without additional sensors. To activate the start-up assistant, the brake pressure applied by the driver is monitored. In this case, the driver must feed a certain pressure in the service brake for a certain time to trigger an automatic vehicle standstill on the mountain.

at most of the brake devices described above are the Starting aids automatically activated. In addition, it is known to activate the traction help by simultaneously pressing the brake pedal and a switch is operated become.

Other Systems use longitudinal acceleration sensors or longitudinal acceleration estimates, by means of which a slope can be determined. Dependent on from the determined slope and other conditions, such as Example, the brake pressure applied by the driver, the can Maintaining the vehicle standstill required on the mountain Brake pressure automatically be controlled in the wheel brakes of the vehicle.

The start-up aids for detecting vehicle standstill usually use the wheel speed sensors of the ABS system ( DE 198 25 642 A1 ). In this case, there is a risk that a shutdown of the wheels is erroneously concluded to be a standstill of the entire vehicle, even though the vehicle slips with locked wheels. Such activation may result in false activations at low friction levels. Since some functions, such as the "Rill-Start-Assist" (HSA), are to be activated only when the vehicle is stationary, in addition to the wheel speed signals, special controller methods monitor whether the vehicle is showing any signs of slipping active and should determine whether the vehicle slips with locked wheels, so that, for example, the affected controller method can be switched off immediately.

The Slip detection evaluates the yaw rate signal of the ESP controller, because vehicles have a slight rotational movement when they start to slide. Steering movements lead likewise to a slight yaw movement of the vehicle and provide from a control point of view, a disturbance variable for slip detection. Without suitable measures, it is possible to slide over strong Steering movements as they occur when maneuvering a vehicle can, trigger.

Of the Invention is therefore the object of a method and a Start-up assistant and provide a device that ensures that the activated slip detection is not supported by additional caused by the driver steering movements was triggered.

These The object is solved by the features of the independent claims. advantageous Further developments are specified in the subclaims.

• a) Ermitteln des Fahrzeugstillstands anhand des Drehverhaltens des Fahrzeugs,
• b) Einleiten der selbsttätigen Fortsetzung des Betriebszustandes durch Einsteuern oder Halten eines Betriebsbremsdruckes,
• c) Überprüfen des Betriebszustandes mittels Fahrdynamikgrößen und/oder Fahrdynamikzuständen,
• d) Aufheben der selbsttätigen Fortsetzung des Betriebszustandes in Abhängigkeit von dem Überprüfungsergebnis und
• e) Einleiten einer Sonderregelung zur Stabilitäts- oder Traktionskontrolle

wobei die Fahrdynamikgrößen und/oder Fahrdynamikzustände zur Ermittlung des Fahrzeugstillstandes gegenüber bekannten Störgrößen und/oder Störzuständen in Bezug gesetzt, neu bestimmt und als Überprüfungsergebnis der Sonderregelung zur Stabilitäts- oder Traktionskontrolle zugeführt werden.According to the invention, it is provided that the following steps are carried out to determine a sliding process:

• a) determining the vehicle standstill based on the rotational behavior of the vehicle,
• b) initiating the automatic continuation of the operating state by controlling or holding a service brake pressure,
• c) checking the operating state by means of driving dynamics variables and / or driving dynamics states,
• d) canceling the automatic continuation of the operating state depending on the test result and
• e) introducing a special stability or traction control system

wherein the driving dynamics parameters and / or driving dynamics states for determining the vehicle standstill with respect to known disturbance variables and / or interference states related, re-determined and fed as a check result of the special control for stability or traction control.

In A further embodiment of the invention provides that for checking the operating state evaluated the vehicle, the steering angle and / or its derivatives becomes.

In a further embodiment of the invention, an estimate of the yaw rate Ψ takes place. as the vehicle dynamics quantity, the disturbance quantity of the proportion von attributable to the execution of a steering movement. _Steer of yaw rate Ψ. of the vehicle and the result of the check is the difference Ψ. - Ψ. _Steer the special control for stability or traction control supplied.

• a) Ermitteln eines Fahrzeugstillstands anhand vom Drehverhalten der Fahrzeugräder,
• b) Einleiten der selbsttätigen Fortsetzung des Betriebszustandes durch Einsteuern oder Halten eines Betriebsbremsdruckes,
• c) Überprüfen des Betriebszustandes mittels Fahrdynamikgrößen und/oder Fahrdynamikzuständen,
• d) Aufheben der selbsttätigen Fortsetzung des Betriebszustandes in Abhängigkeit von dem Überprüfungsergebnis
• e) Einleiten einer Sonderregelung zur Stabilitäts- oder Trak tionskontrolle

und die Fahrdynamikgrößen und/oder Fahrdynamikzustände zur Ermittlung des Fahrzeugstillstandes gegenüber bekannten Störgrößen und/oder Störzuständen in Bezug gesetzt, neu bestimmt und als Überprüfungsergebnis der Sonderregelung zur Stabilitäts- oder Traktionskontrolle zugeführt werden.A particularly advantageous embodiment of the invention is the approach assistant for assisting the startup of a vehicle uphill where the steps

• a) determining a vehicle standstill based on the rotational behavior of the vehicle wheels,
• b) initiating the automatic continuation of the operating state by controlling or holding a service brake pressure,
• c) checking the operating state by means of driving dynamics variables and / or driving dynamics states,
• d) Canceling the automatic continuation of the operating state as a function of the Check result
• (e) the introduction of a special stability or traction control system

and set the driving dynamics parameters and / or driving dynamics states for determining the vehicle standstill in relation to known disturbance variables and / or fault conditions, re-determined and supplied as a check result of the special control for stability or traction control.

To The invention provides an advantageous start-up assistant, the driving dynamics variables the Yaw rate and / or the steering angle and / or their derivatives and / or freely rotating wheels and as driving dynamics states Intervention of an anti-skid control, traction control and / or used a yaw moment control.

One embodiment is shown in the drawing and will be described in more detail below.

Show it

1 a schematic representation of the forces acting on a vehicle during a vehicle movement on a slope.

2 a simplified block diagram of an elimination of a distraction caused by the steering and passing the corrected yaw rate to the slip detection module

wird durch die Gewichtskraft bestimmt.The invention is based on the knowledge that a vehicle ( 1 ), which from the driving state into a stationary state on a mountain ( 2 ) and equipped with a start-up assistant, can slip. On a slope, the gradient resistance G _g · sin α _St ( 3 ) counteracts the longitudinal force F _x , which is required to keep the vehicle at a standstill in the mountains. The friction coefficient necessary to transmit the longitudinal force

is determined by the weight.

A slippage of the vehicle can be triggered or influenced by the operating state of the standstill with a low coefficient of friction (eg on ice) and / or a large incline and / or high vehicle weight. An additional influencing factor is also the position of the center of gravity ( 4 ) and its change with the loading of the vehicle. If it exceeds a liability limit between the tires of the vehicle and the ground, the vehicle begins to move downhill.

The Invention advantageously makes the skid detection of the ESP controller towards steering wheel movements robust at standstill.

The method consists in that the portion attributable to steering movements Ψ. _Steer ( 30 ) of the yaw rate Ψ. ( 31 ) of the vehicle and supplied to the skid detection algorithm as a disturbance. This proportion is calculated from the steering angle Θ ( 32 ) and its derivative Θ. ( 33 ) and a factor k → Steer = (k _Θ , k _Θ ) ( 34 ) With

2 shows how the corrected yaw rate Ψ. _Corr 34 ) is obtained by subtracting the steering ratio: Ψ. Corr = Ψ. - Ψ. Steer ,

Alone the corrected yaw rate enters the slip detection, which now across from Steering movements in the stance is robust.

By the connection of the steering movement as a disturbance succeeds, the slip detection across from to make violent steering movements insensitive. This allows the Slip detection simultaneously with respect to the yaw rate component, which is due to chutes, be made more sensitive.

critical is that based on steering angle and steering angle speed of the appropriate proportion of the yaw rate of the vehicle is estimated, which is due to the steering movement at a standstill. The slip detection method then uses the yaw rate corrected by this percentage.

Claims (7)

A method for determining a skid, wherein the following steps are carried out: b) determining the vehicle standstill based on the rotational behavior of the vehicle, b) initiating the automatic continuation of the operating state by controlling or holding a service brake pressure, c) checking the operating state by means of vehicle dynamics variables and / or driving dynamics states, d) canceling the automatic continuation of the operating state as a function of the test result and e) introducing a special control for stability or traction control, characterized in that the driving dynamics parameters and / or driving dynamics states for determining the vehicle stationary set in relation to known disturbance variables and / or fault conditions, re-determined and fed as a check result of the special control for stability or traction control. Method according to claim 1, characterized that for checking the Operating state of the vehicle, the steering angle and / or its derivatives is evaluated. Method according to one of claims 1 to 2, characterized in that the yaw rate Ψ. as the driving dynamics quantity, the disturbance variable of the portion Ψ attributable to the execution of a steering movement. _Steer of yaw rate Ψ. estimated value of the vehicle and as the result of the examination the difference Ψ. -Ψ. _Steer the special control for stability or traction control is supplied. Method according to one of claims 1 to 3, characterized that in dependence from the check result the brake pressure is reduced. Method according to one of claims 1 to 4, characterized that in dependence from the check result the brake pressure is reduced and built up. Start assist to assist the start of a vehicle uphill in which the steps a) Determining a vehicle standstill based on the rotational behavior of the vehicle wheels, b) Initiate the automatic Continuation of the operating state by controlling or holding a service brake pressure, c) Checking the Operating state by means of vehicle dynamics variables and / or driving dynamics states, d) Cancel the automatic Continuation of the operating state depending on the result of the check e) Initiation of a special regulation for stability or traction control. thereby marked that the driving dynamics parameters and / or driving dynamics states for Determination of vehicle standstill against known disturbance variables and / or Fault conditions in Reference set, newly determined and as the result of the check of the special regulation for stability or traction control supplied become. Anfahrassistent according to claim 6, characterized that as driving dynamics variables the Yaw rate and / or the steering angle and / or their derivatives and / or freely rotating wheels and as driving dynamics states Interventions of an anti-skid control, a traction control system and / or yaw moment control.