DE102009039028B4 - Method and device for detecting the steering wheel activity of a driver - Google Patents

Abstract

A method of detecting the steering wheel activity of a driver of a motor vehicle equipped with a driver assistance system acting on the steering of the motor vehicle, wherein in a first block (1) the manual steering torque (FM) exerted on the steering wheel by the driver is determined, the manual steering torque (FM) is differentiated, and the amount of the differentiated manual steering torque forms the steering torque velocity (LMV), which is compared with a predetermined first threshold (S1), so that the result of the comparison results in the value of a first Boolean variable (B1), in a second block (5) determined by the driver assistance system to the steering torque (RM) is determined, the control torque (RM) is differentiated, and the amount of the differentiated control torque (RM) the control torque (RMV) results, from the control torque (RMV) a steering torque change limit (LMG) is derived , and the steering torque (LMV) with the Lenkmomentänderun gsgrenze (LMG) for determining the value of a second Boolean variable (B1) is compared, and is derived from a logical operation (11) of the first and second Boolean variables (B1, B2), whether the driver has taken the steering wheel or not.

Description

The invention relates to a method for detecting the steering wheel activity of a driver with a driver assistance system acting on the steering of the motor vehicle, a device for carrying out such a method and the use of such a device in a lane keeping assistance system.

To increase safety when operating a motor vehicle on the road, driver assistance systems are increasingly being used, which are aimed at increasing driving safety. Such assistance systems assist the driver or may act in emergency situations instead of the driver. One system currently in use is the ADR system, also known by the abbreviation ACC (Automatic Cruise Control), in which both a cruise control and a cruise control are interlinked. Furthermore, lane keeping assistance systems (heading control) are familiar in which the lane is detected by means of an appropriate sensor system and the system tries to keep the vehicle on the lane by correspondingly enforced steering operations. Such systems usually require an electric motor assisted steering. Furthermore, combinations of said system are under development.

In order to bring about a further improvement in the active safety, it is necessary to obtain information about the driver with regard to his ability to react, since in an overtired driver, the aforementioned driver assistance systems also fail. A monitoring of the driver and a subsequent assessment of his condition are possible in various ways. For example, the steering and / or acceleration / braking behavior of the driver can be monitored and evaluated. A fundamental question in monitoring driver activity is whether or not the driver has ever caught the steering wheel while driving. If he has not detected the steering wheel, it is reasonable to assume that the driver is in a state of reduced attention and that measures, for example in the form of a warning, must be taken.

From the DE 10 2005 056 438 A1 A method for clarifying the question of whether the driver of a motor vehicle has taken the steering wheel or not. In the method, such parameters of the steering wheel are measured and evaluated, which determine the system behavior of the steering wheel. The evaluated parameters are then compared with reference parameters, wherein the reference parameters reflect either the situation in which the driver holds the steering wheel or in which the driver has not taken the steering wheel. If the deviation between the evaluated parameters and the reference parameter is greater than a predetermined threshold, a warning, ie an alarm, is triggered.

Furthermore, from the DE 198 06 458 A1 a vehicular steering apparatus having a free-hand recognizing apparatus, in which the hands-free travel is detected on the basis of at least the vehicle speed and the steering torque. In this case, the journey is assessed as freehand if the vehicle speed is greater than a predetermined speed value and the measured steering torque is less than a predetermined threshold.

A disadvantage of the above methods or devices is that a superfluous warning can be triggered when the driver has intentionally taken both hands off the steering wheel for a short time. Superfluous warnings reduce the acceptance of such a system.

Furthermore, the post-published publication describes DE 10 2008 021 150 A1 a method for detecting a driver's hands-free travel, in which the absolute value of the driver's manual steering torque and / or its derivative is determined, wherein a hand-off case is closed, if for a predetermined time, a predetermined value of the manual steering torque and / or the Manual steering torque is not exceeded.

The publication DE 60 2004 012 105 T2 discloses a method for detecting the steering wheel activity of a driver of a motor vehicle equipped with a driver assistance system acting on the steering of the motor vehicle, wherein in a first block the force exerted by the driver on the steering wheel manual steering torque is determined, the manual steering torque is differentiated, and the amount of differentiated manual steering torque Lenkmomentgeschwindigkeit forms, which is compared with a predetermined first threshold, so that the result of the comparison results in the value of a first Boolean variable, and
in a second block, the control torque exerted by the driver assistance system on the steering is determined and the first threshold value is adjusted as a function of the control torque.

The publication DE 198 06 458 A 1 likewise discloses a method for detecting the steering wheel activity of a driver of a motor vehicle equipped with a driver assistance system acting on the steering of the motor vehicle, which method is based on the method of the document cited above DE 60 2004 012 105 T2 equivalent.

Since, in the regulation of the driver's manual steering torque, the predetermined torque value to be undershot for detecting a free-hand travel is relatively small, vehicle or steering-specific tolerances, for example friction in the steering system or an offset in the steering torque sensor, can lead to the hands-off case, ie the freehand, is not recognized. Likewise, a control based on the manual steering torque velocity due to the fixed and low comparison limit can lead to erroneous behavior.

The invention is therefore an object of the invention to provide a method and an apparatus for improved detection of a free travel of a driver of a vehicle equipped with a driver assistance system motor vehicle.

The object is achieved by a method having the features of claim 1, by an apparatus having the features of claim 7 and by the use of such a device having the features of claim 10. Preferred embodiments are the subject of the dependent claims.

• in einem ersten Block wird das vom Fahrer auf das Lenkrad ausgeübte Handlenkmoments bestimmt, dieses Handlenkmoment wird differenziert, es wird der Betrag des differenzierten Handlenkmoments gebildet, der die Lenkmomentgeschwindigkeit darstellt, und diese Lenkmomentgeschwindigkeit wird mit einer vorgegeben ersten Schwelle verglichen, so dass sich als Ergebnis des Vergleichs ein Wert einer ersten boolschen Variablen ergibt,
• in einem zweiten Block wird das vom Fahrerassistenzsystem auf die Lenkung ausgeübte Regelmoment bestimmt, dieses wird Regelmoment differenziert, es wird der Betrag des differenzierten Regelmoments gebildet, der die Regelmomentgeschwindigkeit darstellt, aus der Regelmomentgeschwindigkeit wird eine Lenkmomentänderungsgrenze abgeleitet, und es wird die Handlenkmomentgeschwindigkeit mit der Lenkmomentänderungsgrenze zur Bestimmung eines Werts einer zweiten boolschen Variablen verglichen, und
• es wird aus einer logischen Verknüpfung der ersten und zweiten boolschen Variablen abgeleitet, ob der Fahrer das Lenkrad ergriffen hat oder nicht.

The inventive method for detecting the steering wheel activity of a driver of a vehicle equipped with a driver assistance system acting on the steering of the motor vehicle has the following features:

• in a first block, the manual steering torque exerted by the driver on the steering wheel is determined, this manual steering torque is differentiated, the amount of the differentiated manual steering torque representing the steering torque speed is formed, and this steering torque speed is compared with a predetermined first threshold, so that as a result of the comparison gives a value of a first Boolean variable,
• in a second block, the control torque exerted on the steering by the driver assistance system is determined, this control torque is differentiated, the amount of the differentiated control torque representing the control torque speed is calculated, a steering torque change limit is derived from the control torque speed, and the manual steering torque with the steering torque change limit is determined to compare a value of a second Boolean variable, and
• It is derived from a logical combination of the first and second Boolean variables, whether the driver has taken the steering wheel or not.

Preferably, the manual steering torque of the driver and the control torque of the assistance system in the differentiation step are each subjected to a filtering. This compensates for short-term fluctuations in the measurements.

To determine the steering torque change limit, the maximum is preferably formed between the amount of the control torque speed and a predetermined second threshold. Further, for further determination of the steering torque change limit, the minimum between the maximum resulting in the previous step and a third threshold is formed.

Preferably, the first Boolean variable and the second Boolean variable will be ORed to a third Boolean variable. This third Boolean variable is used to determine if the driver has grabbed the steering wheel or not.

More preferably, the third Boolean variable controls a switch, wherein as a function of the third Boolean variable the output of the controlled switch either reduces a counter for detecting a non-engagement of the steering wheel by a predetermined first increment or the counter is subjected to a RESET, since the driver Steering wheel has seized.

The device according to the invention for carrying out the above-explained method comprises a sensor unit for determining the driver's manual torque, a control device for acting on the steering unit of the motor vehicle with a control torque, a sensor unit for determining the control torque, and a control and evaluation unit for determining a free-hand drive of the driver the driver's manual torque and the control torque.

Preferably, the device is clocked and has a device for determining a time duration during which the driver does not generate a steering torque speed on the steering wheel. Preferably, the device has an electric motor assisted steering.

A preferred use of said device is the use in a lane keeping assistance system of a motor vehicle for determining whether or not the driver has a free ride. The device or the method explained above can of course also be used in other assistance systems that can exert a control torque on the steering device and in which there is a need to recognize whether the driver has taken the steering wheel, the so-called hands-on case , or whether the driver has not taken the steering wheel, also referred to as a hands-off case.

Therefore, in the case of the lane departure warning system, if this establishes a control torque, the manual steering torque exerted by the driver increases more in the "hands-on" case than in the "hands-off" case, the increase or its absolute value being dependent on the axle load-dependent steering characteristic curve. The limit below which the steering torque should be depends on the control torque of the lane departure warning system. For this purpose, the "limit" is preferably adapted to the control torque during a steering intervention of the assistant, so that the measured response to the steering torque sensor, which is measured solely due to the inertia of the steering wheel, does not adversely affect the detection of driver activity on the steering wheel. At the same time, a relatively large change in the steering torque rate causes the hands-off detection to be reset.

• 1 ein Blockschaltbild der Vorrichtung zur Erkennung der Fahreraktivität am Lenkrad eines Kraftfahrzeugs.

A preferred embodiment of the invention will be described below with reference to the single drawing. It shows

• 1 a block diagram of the device for detecting the driver activity on the steering wheel of a motor vehicle.

The device for detecting the driver activity on the steering wheel of a motor vehicle has a sensor device, not shown, for determining the driver's hand torque exerted by the driver on the steering wheel FM and a device, not shown, for determining a control torque exerted by a driver assistance system as a result of a control intervention on the steering unit RM on. As a driver assistance system, for example, a lane keeping assistance system comes into question, which acts on an electro-mechanical steering.

The measured driver's hand moment FM is in a first processing block 1 a filtering and differentiation in a corresponding unit 2 subjected. Thereafter, the filtered and differentiated signal, which is still signed, becomes an amount formation 3 and the amount of the differentiated signal is obtained. Since the question is to be decided as to whether or not the driver has grasped the steering wheel, the direction of the steering torque does not depend on the following, and therefore, the magnitude of the differentiated signal becomes the steering torque speed LMV designated. The steering torque speed LMV will be in a comparator 4 with a first threshold S1 to compare. If the comparison is positive, ie if the steering torque is greater than the first threshold S1 is, so gets a first Boolean variable B1 the value "1". If the comparison is negative, then the first Boolean variable B1 set to the value "0".

In a second block 5 is concurrently the torque generated by an assistance system on the steering RM determined and a filtering and differentiation in a corresponding device 6 subjected. The differentiated signal is associated with a sign, which in an absolute value 7 is removed, wherein the direction independent amount of the differentiated signal as a control torque velocity RMV referred to as. In one unit 8th becomes the maximum between the control torque speed RMV and a second threshold S2 educated. In other words, the control torque speed RMV must exceed a lower limit, here by the second threshold S2 is realized. The maximum thus formed M is then restricted to an upper limit by setting the minimum between the maximum determined M and a third threshold S3 in a corresponding facility 9 is formed. The signal thus limited up and down sets the steering torque change limit LMG ie, forms the limit under which the steering torque speed LMV must lie, so that a free-hand condition is accepted. In a comparator 10 therefore becomes a second boolean variable B2 from a comparison between the one in the first block 1 determined steering torque velocity LMV and in the second block 5 determined steering torque change limit LMG certainly. Is the steering torque speed LMV greater than or equal to the steering torque change limit LMG so becomes the second Boolean variable B2 assigned the value "1". If the comparison is negative, the second Boolean variable receives the value "0".

The first block 1 determined first Boolean variable B1 and in the second block 5 determined second Boolean variable B2 are in an OR operation 11 to a third boolean variable HOR linked, where the variable HOR has the effect of a hands-off RESET, as will be apparent from the following.

The third Boolean variable HOR becomes the control input of a controllable switch 12 fed. Is the value of the variable HOR "0", so will the output A of the switch 12 a first increment SW1 supplied and in the case of "1" a second step size SW2 , As possible step sizes, for example SW1 the value -1 and SW2 have the value 1000.

The exit A of the switch 13 becomes a counter unit 13 fed. This counter unit 13 serves to track the freewheeling of the motor vehicle over a long period of time to generate when exceeding a predetermined period of time, the message that the driver has not taken the steering wheel. Since the in 1 If the device is clocked, the counter is counted down 13 starting from a given initial number at a defined time interval. So knows the counter 13 is the value n at the current clock and is the boolean variable HOR this clock "0" becomes -1 for the first increment SW1 added to the counter value n, leaving the counter 13 then has the value n-1. Holds therefore the third Boolean variable HOR the value "0" until the counter 13 reaches or falls below the value 0, the counter unit resets 13 the value of a fourth Boolean variable HO to "0", which means that the driver does not have his hands on the steering wheel for a given period of time. In other words, in this case, the hands-off state is signaled.

Has the variable Hands-Off-Reset HOR the logical value "1" becomes the second increment SW2 on the output of the switch 12 connected. If the second step size has the above-mentioned high value of, for example, 1000, then the counter is reinitialized and a reset is thus carried out. This has the Boolean output variable HO the counter unit is "1", which means that the driver has his hands on the steering wheel and a possible hand-off message must be reset.

The described device or method is also based on the idea that when the driver holds the steering wheel and the lane departure warning by means of a control torque engages in the action, so quickly builds a driver's steering torque, and faster than if the driver's hands were not on the steering wheel , As a result, the steering torque change, i. the steering torque is high, and the hands-off signal is reset.

• S1: 0,5 Nm/s, S2: 0,075 Nm/s, S3: 1 Nm/s, SW1: 1 und SW2: 1000

Preferred values of said thresholds and step sizes are as follows:

• S1 0.5 Nm / s, S2 0.075 Nm / s, S3 : 1 Nm / s, SW1 : 1 and SW2 : 1000

LIST OF REFERENCE NUMBERS

FM

Driver manual torque

RM

Rule moment of the assistance system

LMV

Steering torque speed

RMV

Modulating torque speed

M

maximum

S1

first threshold

S2

second threshold

S3

third threshold

LMG

Steering torque change limit

B1

first boolean variable

B1

second boolean variable

HOR

Hands-off reset (third boolean variable)

SW1

first step

SW2

second step

A

switch output

HO

Hands-off (fourth boolean variable)

1

Block 1

2

Filter and differentiate

3

magnitude formation

4

comparator

5

Block 2

6

Filter and differentiate

7

magnitude formation

8th

Maximum formers

9

minimum Education

10

comparator

11

Or link

12

controlled switch

13

counter unit

Claims (10)

A method for detecting the steering wheel activity of a driver of a vehicle equipped with a driver assistance system acting on the steering of the motor vehicle, wherein in a first block (1) the hand steering torque (FM) exerted by the driver on the steering wheel is determined, the manual steering torque (FM) is differentiated, and the amount of the differentiated manual steering torque forms the steering torque speed (LMV) which corresponds to a predetermined first threshold (S1 ) is compared, so that the result of the comparison results in the value of a first Boolean variable (B1), in a second block (5) the control torque (RM) exerted on the steering by the driver assistance system is determined, the control torque (RM) is differentiated, and the magnitude of the differentiated control torque (RM) gives the control torque speed (RMV), from the control torque speed (RMV a steering torque change limit (LMG) is derived, and the steering torque speed (LMV) is compared with the steering torque change limit (LMG) for determining the value of a second Boolean variable (B1), and is derived from a logical operation (11) of the first and second Boolean variables (B1, B2), whether the driver has taken the steering wheel or not. Method according to Claim 1 , characterized in that the manual steering torque (FM) and the control torque (RM) are subjected to filtering in the differentiating step. Method according to Claim 1 or 2 , characterized in that for determining the steering torque change limit (LMG), the maximum (M) between the amount of the control torque speed (RMV) and a predetermined second threshold (S2) is formed. Method according to Claim 3 , characterized in that for determining the steering torque change limit (LMG), the minimum between the resulting maximum (M) and a third threshold (S3) is formed. Method according to one of the preceding claims, characterized in that the first Boolean variable (B1) and the second Boolean variable (B2) are combined with an OR operation (11) to form a third Boolean variable (HOR) which is used for the determination whether the driver has grabbed the steering wheel or not. Method according to Claim 5 , characterized in that the third Boolean variable (HOR) drives a switch (12), the output (A) of the switch (12) either being the value of a counter (13) for detecting a value as a function of the third Boolean variable (HOR) Non-engagement of the steering wheel by a predetermined first increment (SW1) is reduced or the counter (13) is subjected to a RESET, since the driver has taken the steering wheel. Apparatus for carrying out the method according to one of the preceding claims with a sensor unit for determining the driver's manual torque, a control device for acting on the steering unit of the motor vehicle with a control torque, a sensor unit for determining the control torque, and a control and evaluation unit for determining a free-hand drive of the driver the driver's manual torque and the control torque. Device after Claim 7 , characterized in that the device is clocked and has means (13) for determining a period of time during which the driver does not generate a steering torque speed on the steering wheel. Device after Claim 7 or 8th , characterized in that the device has an electric motor assisted steering. Use of the device according to one of Claims 7 to 9 in a lane keeping assistance system of a motor vehicle for determining whether or not there is a driver's hands-free ride.

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