DE102008021150A1 - Method for identification of missing driver activity at steering wheel of motor vehicle, involves determining hand moment of driver exerted at steering wheel - Google Patents

Abstract

The method involves determining the hand moment (HM) of the driver exerted at the steering wheel. A hand moment size is determined from the measured hand moment. A counter around a predetermined step size (SW1) is decremented based on the counter value of the previous clock if the hand moment size is smaller than the predetermined threshold (HMS1). The new counter value is stored for use in the next clock. An independent claim is included for a device for executing the missing driver activity identification method.

Description

The The invention relates to a method for detecting missing driver activity on the steering wheel of a motor vehicle according to the preamble of claim 1 and a corresponding device according to the The preamble of claim 10.

to Increasing safety during operation of a motor vehicle In road traffic, driver assistance systems are increasingly being used used, aimed at increasing driving safety are. Such assistance systems support the driver or may be used in emergency situations instead act of the driver. A system currently in circulation is the ADR system (automatic distance control), also under the Abbreviation ACC (Automatic Cruise Control) known in which both a cruise control and a distance control linked together. Next are lane keeping systems (Heading Control), in which by means of a corresponding Sensors recognized the lane and the system by accordingly forced steering attempts to get the vehicle on the To keep the lane. Such systems set an electric motor assisted steering ahead. Furthermore, combinations from the mentioned system in development.

Around now to bring about a further improvement in active safety, it is necessary to have information about the driver to gain his ability to react, as in an over-tired Driver also fail the above driver assistance systems. A monitoring of the driver and a subsequent Assessment of his condition are possible in different ways. For example, the steering and / or acceleration / braking behavior be monitored and evaluated by the driver. A basic one Question in the monitoring of driver activity is whether the driver while driving at all the steering wheel has seized or not. Does this not the steering wheel recorded, it is obvious that the driver in a State of reduced attention is located and that action, for example, in the form of a warning must be taken.

From the DE 10 2005 056 438 A1 is a method for clarifying the question of whether the driver of a motor vehicle has taken the steering wheel or not to refer, in which such parameters of the steering wheel measured that determine the system behavior of the steering wheel and these parameters are evaluated. 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.

adversely in the known methods or devices is that a superfluous Warning may be triggered when the driver intentionally briefly removed both hands from the steering wheel. superfluous Warnings reduce the acceptance of such System.

Of the Invention is therefore based on the object, a method and a device for detecting missing driver activity to create the steering wheel of a motor vehicle, reducing the number unjustified warnings to the driver is reduced.

The The object is achieved by a method having the features of the claim 1 and by a device with the features of claim 10 solved. Preferred embodiments of the method are Subject of the dependent claims.

• – Bestimmen mindestens einer Handmomentgröße aus dem gemessenen Handmoment,
• – Herunterzählen eines Zählers um eine vorgegebene erste Schrittweite ausgehend von dem Zählerwert des vorherigen Taktes, wenn die mindestens eine Handmomentgröße kleiner als eine vorgegebene erste Schwelle ist,
• – Abspeichern des neuen Zählerwertes zur Verwendung im nächsten Takt,
• – Vergleichen des neuen Zählerwertes mit einem Zählerschwellwert und Ausgeben einer Warnung, wenn der neue Zählerwert kleiner dem Zählerschwellwert ist, und
• – Ausführen des nächsten Taktes, wenn der neue Zählerwert größer oder gleich dem Zählerschwellwert ist.

The inventive method for detecting missing driver activity on the steering wheel of a motor vehicle, wherein the force exerted on the steering wheel hand torque of the driver is measured is clocked and has within a cycle of predetermined cycle time the following steps:

• Determining at least one moment of hand torque from the measured hand moment,
• Counting down a counter by a predetermined first increment starting from the counter value of the previous clock, when the at least one manual torque is smaller than a predetermined first threshold,
• Storing the new counter value for use in the next clock,
• Comparing the new counter value with a counter threshold value and outputting a warning if the new counter value is smaller than the counter threshold value, and
• - Execute the next clock if the new counter value is greater than or equal to the counter threshold value.

Preferably the counter is incremented by a second increment counted up to the count of the previous bar, if the at least one moment of hand size is greater or equal to the predetermined threshold. It is further preferred, that the second step size is a function of the manual moment size is.

With In other words, the idea underlying the invention consists to trigger a warning when the torque threshold longer than a given but variable period of time the driver's manual torque is exceeded. This is the manual torque of the driver with a predetermined frequency performed and a counter counted down, as long as the condition of falling below is true. Meets the condition not to, d. H. the measured manual torque is greater or equal to the momentary threshold, the counter becomes again counted up, with the speed with which the counter is counted up again, one Function of the applied hand torque is. A warning of Driver therefore only occurs when the value of the meter falls below a predetermined threshold, which only after a certain Time can be done. This ensures that the system is flexible Responded to activities of the driver.

Especially is preferably the manual torque with a second threshold, wherein the second step size one assumes greater value when the hand momentum size is greater than the second threshold, and one assumes smaller value when the manual torque size is less than or equal to the second threshold.

In a preferred embodiment is the Cycle time approx. 0.2 seconds. This is to express that the cycle time or cycle time is in the range of a few tenths of a second moved to within a reasonable period of a few seconds to get a statement about the driver's activity.

Further is preferably the counter value by an upper limit limited, wherein the first and / or second step size and / or first threshold and / or upper limit of the counter value can be changed depending on the situation are.

Under the term manual torque is here on the one hand understood the manual torque of the driver himself, d. H. the procedure is based on the evaluation of the manual torque of the driver, on the other hand is also the time derivative of the measured manual torque understood, which means that the procedure on the evaluation the time derivative of the manual torque is directed. The procedure can also be combined in the sense that it is contemplated directed both hand torque.

Therefore is preferably the manual torque by the measured hand moment and / or its time derivative formed. In other words, in a preferred embodiment becomes the manual torque of the driver within a stroke or cycle while in the other case the scheme is up the time derivative of the manual torque is directed. Further is It also makes the procedure both contemplative to support the hand moment as well as its derivative with In other words, the procedure is a combination of evaluation of the Hand moments and its derivative is. When considering the Derivation of the manual torque, this can be preferably filtered, to achieve a smoothing of the signal curve.

A inventive device for implementation of the method explained above has at least a sensor for determining the hand wheel torque applied to the steering wheel, a data processing device for carrying out the Procedure and a warning device.

Preferably the warning device by a display device and / or an acoustic warning device is formed. Furthermore, the device have a sensor for determining the steering wheel angle.

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

1 a block diagram of the device for detecting missing driver activity on the steering wheel, and

2 the method for detecting missing driver activity on the steering wheel in a schematic representation.

1 shows a block diagram of a device for detecting missing driver activity, as can be used for example in a lane departure warning based on a steering torque sensor. Shown is an electromechanical steering 1 that with a steering wheel 2 connected is. A driver 3 exercises active steering movements on the steering wheel 2 out, so that the manual torque HM of the driver 3 on the electromechanical steering 1 acts. An unillustrated sensor measures that on the steering wheel 2 and therefore the electromechanical steering 1 applied manual torque HM of the driver, which to a control unit 4 is transmitted. Another sensor can also optionally measure a high-resolution steering wheel angle and to the control unit 4 transfer. In the control unit 4 is carried out on the basis of the measured manual torque of the driver, the method for detecting missing driver activity on the steering wheel. If a missing driver activity has been detected, the controller triggers a display or warning device 5 that gives an optical and / or acoustic and / or haptic warning to the driver.

2 shows a schematic representation of the inventive method for detecting missing or lack of driver activity on the steering wheel, so to detect a free steering wheel. The measured manual torque HM of the driver of the current measurement cycle is an input value to an absolute value generator 10 fed, which forms the amount of the manual torque HM. The magnitude value of the manual torque HM is in a first comparator 11 with a lower first threshold HMS1 and in a second comparator 12 compared with an upper second threshold HMS2, being the first comparator 11 the boolean variable V1 and the second comparator outputs the boolean variable V2.

Is the comparison in the first comparator 11 positive, ie the measured manual torque HM is greater than the first threshold HMS1, then the Boolean variable V1 of the comparator 11 the boolean value "one". If, on the other hand, the comparison is negative, ie the magnitude of the measured manual torque HM is less than or equal to the first threshold HMS1, then the Boolean variable V1 has the value logic "zero".

The boolean variable V1 of the comparator 11 controls the logical input E2 of a switch 13 which still has the further inputs E1 and E3 and the output A. It chooses in the comparator 11 as in the comparators yet to be explained 12 and 13 , the control input E2 off, which of the two other inputs E1 and E3 is switched to the output a. Therefore, if E2 is at logic "one", the input E1 is switched to the output A, in the other case the input E3.

Is therefore the comparison in the comparator 11 negative, that is, the amount of the measured manual torque HM is less than or equal to the first threshold HMS1, the Boolean variable V1 has the value "zero", which causes the switch 13 the first step width SW1 applied to the input E3 to the output A of the switch 13 sets. In a preferred embodiment, the first step size SW1 has the value "-1". If you want to count faster down, a larger negative number can be the value of the first increment SW1.

The way to the output of the switch 13 switched through first increment SW1 with the negative value is an acting as a counter adder 14 supplied to the other input, the counter value of the previous clock is applied. Therefore, if the first step size is "-1", then the counter or adder becomes 14 counted down. The new counter value of the current measuring cycle now becomes a maximum generator 15 which determines the maximum between the current counter value and a lower counter limit, which here has the value "0". This always limits the current counter value down to the value "0". Values other than "0" for limiting the counter value when counting down are, of course, conceivable. As long as the current count value is greater than "0", the output of the maximum creator appears 15 the counter value of the current measure.

The current counter value is then passed through a minimum former 16 limited to the top. In the minimum former, the minimum between the current counter value and an upper counter value limit ZWM is determined. Therefore, as long as the counter value ZW is smaller than the upper limit ZWM, the current counter value ZW becomes a comparator 18 fed. In the comparator 18 the current counter reading is compared with a limit value ZWG. If the comparison is negative, ie the current payer value is greater than the counter limit value SWG, then the Boolean variable V3 generated from the comparison is "zero". If the comparison in the comparator 18 However, positive, ie the counter value ZW falls below the limit ZWG, so has the Boolean Variable V3 is the value "one". This signals that the driver is showing substantially no steering activity over an extended period of time, and a warning is generated based on the Boolean variable V3.

The above description deals with the case in which the driver shows no steering activities for a long period of time, so that a hand-off situation must be assumed. Now, while the counter is counting down, the driver can again apply steering torque to the steering wheel, as indicated by the upper part of the process 2 is dealt with.

In the comparator 12 will be parallel to the comparator 11 checks whether a second upper threshold HMS2 is smaller than the amount of the measured manual torque of the driver. If so, the variable V2 has the value "one" and the switch 14 the step size SW3 switches to the input E1 of the switch 13 , If the comparison is not correct, ie the second threshold is greater than the amount of the driver's manual torque, then the Boolean variable has the value "zero", with the result that the step size SW2 is applied to the input E1 of the switch 13 is switched through. The step widths SW2 and SW3 are positive integers having the property that the step size SW3 is greater than the step size SW2. This results in the counter being counted up faster in the case of a large detected manual torque than in the case of a smaller one.

Since the first threshold HMS1 is used to detect a driver's momentary or very small hand torque, whereas the second threshold HMS2 presupposes the presence of a steering torque, the second threshold is to be set greater than the first threshold. Thus, due to the presence of a steering torque of the driver, the Boolean variable V1 is necessarily "one", which causes the input E1 of the switch 13 placed on the output A is. In the presence of a steering torque of the driver is therefore decided by means of the second threshold HMS2, with which step size SW2 or SW3, the counter is counted up again.

The following values for the individual parameters have proven themselves in the method explained above: Cycle time: 0.2 s (ie the procedure is repeated every 0.2 s) ZWM 600 (maximum count) ZWG 100 (lower limit count) HMS1 0.3 Nm (first threshold) HMS2 0.6 Nm (second threshold) SW1 -1 (first step) SW2 15 (second step) SW3 160 (third step)

A Cycle time of 0.2 s means 50 cycles per second. Since in each pass the first increment SW1 = -1 of 600 is deducted, so 10 seconds are needed until the lower limit of the count value ZWG of 100 is reached.

One alternative method would be that instead of the above described use of the measured manual torque of the driver the change of the manual torque dHM / dt is evaluated. Thereby The system will be insensitive to a constant offset if necessary is a filtering of the derivative dHM / dt necessary to a corresponding To get signal quality.

The Principle would be in the case: if the hand moment over not a certain time, so the derivative is small, changes, this is a freehand situation.

Instead of The above moment limits are used in the alternative embodiment Limits used by hand torque changes. For example is a value for the first threshold below which the Counter down counts 0.075 Nm / s.

These first limit can be set depending on the driving condition and increased to 0.3 Nm / s in the case of an active controller intervention become.

Generally Both in the version regarding the hand moments as well as the manual torque changes the warning limits and / or Counter values and / or increments depending on the situation be set. For example, in curves earlier be warned or it can be used as a function of the turning radius the warning limits and / or counter values including Step sizes are changed.

Should For example, be warned in turns earlier, so can to change the first increment from -1 to -2 A warning then already occurs at a cycle time of 0.2 s at 5 s. Alternatively, the value of the maximum count be lowered from 600 to 350, which may also be a earlier warning causes.

1

electromechanical steering

2

steering wheel

3

driver

4

control unit

5

Display / warning device

10

Absolute value

11

first comparator

12

second comparator

13

switch

14

summing

15

maximum generator

16

minimum forming

17

Storage count

18

comparator

HM

manual torque the driver

HMS1

first (lower) threshold

HMS2

second (upper) threshold

SW1

first increment

SW2

second increment

SW3

third increment

V1

first boolean variable

V2

second boolean variable

V3

third boolean variable

ZWM

maximum count

ZWG

lower Limit counter

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102005056438 A1 [0004]
• - DE 19806458 A1 [0005]

Claims (12)

A method for detecting missing driver activity on the steering wheel of a motor vehicle, wherein the force applied to the steering wheel hand torque of the driver is measured, characterized in that the method is clocked and within a cycle of predetermined cycle time comprising the following steps: determining at least one manual torque from the measured manual torque, counting down a counter by a predetermined first increment starting from the counter value of the previous clock if the at least one manual torque is less than a predetermined first threshold, storing the new counter value for use in the next clock, comparing the new counter value with a counter threshold and issuing a warning, if the new counter value is less than the counter threshold, and executing the next clock if the new counter value is greater than or equal to the counter threshold. Method according to claim 1, characterized in that that the counter by a second increment from Counted up to the count of the previous clock becomes, if the manual moment size is greater or is equal to the given threshold, Method according to claim 2, characterized in that that the second step size is a function of the manual moment size is. Method according to claim 3, characterized that the hand momentum with a second threshold is compared, the second step size a larger Takes on value if the manual torque size is greater is considered the second threshold, and assumes a smaller value when the manual torque size is less than or equal to the second Threshold is. Method according to one of the preceding claims, characterized in that the counter value by a upper limit is limited. Method according to one of the preceding claims, characterized in that the first and / or second step size and / or first threshold and / or upper limit of the counter value Depending on the situation are changeable. Method according to one of the preceding claims, characterized in that the manual torque size by the measured hand moment and / or its time derivation is formed. Method according to claim 7, characterized in that that the procedure both on the consideration of the measured Hand moments and its derivative is addressed. Method according to claim 7 or 8, characterized that the time derivative of the manual torque subjected to a filtering becomes. Apparatus for carrying out the method according to one of the preceding claims, characterized the device has at least one sensor for determining the Steering wheel adjacent hand torque, a data processing device to carry out the method and a warning device having. Device according to claim 10, characterized in that that the warning device by a display device and / or an acoustic warning device is formed. Device according to one of claims 10 or 11, characterized in that the device comprises a sensor for determining the steering wheel angle.