DE102011109039A1 - Motor vehicle operating method, involves changing operating phases into free-wheel operation phase, and activating free-wheel operation phase based on expected time curve and longitudinal dynamics control mode - Google Patents

Abstract

The method involves detecting an environment of a vehicle, and determining driving conditions in which a fuel-saving control is provided. Prediction of regulating intervention is carried out during operation phases, and expected time curve (VE) of a state variable (V) is determined based on a travel distance of another vehicle lying ahead of the former vehicle. The operating phases are changed into a free-wheel operation phase i.e. idling operation phase. The free-wheel operation phase is activated based on the expected time curve and a longitudinal dynamics control mode.

Description

The invention relates to a method for operating a vehicle with an adjustable speed-related and / or distance-related longitudinal dynamics control, wherein an environment of the vehicle is detected and driving situations in which a fuel-saving control of a driving speed is possible, are determined.

From the not yet published DE 10 2010 055 373.5 is a method for controlling a longitudinal dynamics of a motor vehicle and a motor vehicle, wherein by means of an object detection unit, an environmental size of the motor vehicle is determined by means of a driving condition detection unit a driving condition of the motor vehicle characterizing driving condition variable is determined and a target acceleration of the motor vehicle in dependence on the driving state variable and the environment size is determined. The longitudinal dynamics of the motor vehicle is regulated as a function of the desired acceleration by means of a motor control unit and a brake control unit, wherein the setpoint acceleration is additionally determined as a function of a weighting factor for lowering a sensitivity of the method in less critical situations for the motor vehicle.

In addition, from the EP 1 475 265 A2 a method for fuel-efficient operation of a vehicle known. The method provides that a target object as well as a first distance to the determined target object are determined and a range of the vehicle is determined on the assumption that there is no operative connection between an internal combustion engine and the drive wheels. Furthermore, a second distance is determined as a function of the first distance and a predefinable tolerance range, wherein the tolerance range is less than or equal to the first distance, wherein further a gear reduction is determined, so that the internal combustion engine is operated in the fuel cut-off mode, if the gear reduction in operative connection with the drive wheels and the internal combustion engine is brought.

The invention has for its object to provide a comparison with the prior art improved method for operating a vehicle with a speed-related and / or distance-related longitudinal dynamics control.

The object is achieved by the features specified in claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method for operating a vehicle having an adjustable speed-related and / or distance-related longitudinal dynamics control, wherein the longitudinal dynamics control operating phases with regulating engagement and operating phases without regulating engagement, an environment of the vehicle is detected and driving situations in which a fuel-saving operation without regulatory intervention possible, determined. According to the invention, a prediction is carried out in operating phases with regulating intervention, by means of which an expected time profile of a state variable is determined as a function of a driving distance ahead of the vehicle, that at the current time a change from the operating phase with regulating intervention into a freewheeling operation, as operating phase would take place without regulating intervention, and that the free-running operation is activated in dependence on the state variable and / or in dependence on a mode of longitudinal dynamics control.

In an advantageous embodiment of the method, the freewheeling operation is an idling operation.

The longitudinal dynamics control in the sense of the invention is understood to mean an operating mode which comprises both operating phases with control intervention and operating phases with suspended control and thus without regulating intervention (= idling phases or free-running phases).

By means of the method, the freewheeling or idling operation of the vehicle is activated in a particularly advantageous manner only in such situations, when a topography of a current and / or the vehicle ahead driving route allows rolling of the vehicle without significant driving speed changes. When determining whether a roll of the vehicle in freewheeling or idling mode for resource-saving, for example, fuel-saving driving makes sense, a slope of the current and the vehicle ahead route is taken into account.

In the longitudinal dynamics control of the vehicle is a constant speed control, also called cruise control, and / or distance control. The longitudinal dynamics control thus preferably includes as operating mode the constant speed control modes, distance during a distance control and approach during a distance control, wherein the freewheeling or idling operation of the vehicle means that an operative connection between a drive unit, such as an internal combustion engine, and the drive wheels of the vehicle is disconnected.

The freewheeling or idling operation is preferably stopped when at least one predetermined termination conditions is met, the transition from freewheeling. or idling operation for the operating phase with regulating intervention is carried out in a sliding manner and is performed within a situation-dependent predefinable fade time. The fade time is specified shorter in particular in dynamic situations than in more agile dynamic situations, so that in dynamic situations a faster system response is obtained than in extensive undynamic situations.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 schematically a time course of an expected idling operation speed of a vehicle,

2 FIG. 2 schematically shows a time profile of a weighting factor expected during idling operation of the vehicle; FIG.

3 to 6 schematically different embodiments of functions of a size for determining a weighting factor.

Corresponding parts are provided in all figures with the same reference numerals.

In 1 is a first diagram 1 with an expected time course V _{E of} a speed v of a vehicle in idle mode, in which a longitudinal dynamics control in an operating phase with suspended control and thus without regulatory intervention is shown. The X-axis represents the time and the Y-axis the velocity v.

The vehicle has a driver assistance system for longitudinal dynamics control, which automatically regulates a torque of an engine of the vehicle or a braking torque of a brake system of the vehicle such that a speed predetermined by a driver is maintained as setting speed v _setting .

The longitudinal dynamics control can be operated in operating modes or phases with regulatory intervention, such as constant speed control or distance during a distance control or approaching a slower target object (emergence to a slower target object) during the distance control. Also, the longitudinal dynamics control can be operated in an operating phase with suspended control and thus without regulating intervention, such as idling operation.

If the driver activates an accelerator pedal or a brake pedal of the vehicle when constant-speed control is activated, the constant-speed control is deactivated or temporarily interrupted.

Furthermore, the vehicle has an environment detection device, by means of which environmental data of the vehicle are detected. The environmental data are detected and / or determined by means of sensor units and preferably by means of map data of a digital road map and / or by means of a satellite-based navigation system.

In addition, the vehicle has an eco-zone determination unit, which is connected to the environment detection device of the vehicle, wherein the vehicle is in a so-called eco mode, which is adjustable with activated longitudinal dynamics control, operable.

If the vehicle is operated in the eco mode, the vehicle is in idle mode, in which an operative connection between a drive unit, such as an internal combustion engine and the drive wheels of the vehicle is disconnected. In idle mode, the drive unit is operated at a predetermined idle speed or put out of service. This will cause consumption, eg. As fuel or electrical energy, reduced during operation of the vehicle.

Depending on an embodiment of the vehicle, instead of the idling mode, another freewheel mode may be selected in which the operative connection between a drive unit of the vehicle and the drive wheels is disconnected.

In this case, the idling operation is adjustable even in a vehicle with automatic transmission in a D-position of the transmission.

If the drive unit is an electric motor by way of example, free-running without engine speed is possible and also conceivable, whereby at the same time consumption of electrochemical energy is at least reduced.

The driver assistance system is activated, for example, in constant-speed control mode, ie, the driver of the vehicle has _{set the setting} speed v _set with which the vehicle is traveling by entering a speed value.

Assuming that the vehicle is to be operated in idle mode from then on, a prediction is performed, in which under Using an environmental data provided by the environmental detection device, an expected state variable is determined with reference to a slope of a current and a driving route ahead of the vehicle.

During operation of the vehicle in an operating phase with regulating intervention, such as when constant cruise control is set, an expected time course V _{E of} a state variable v, in particular the vehicle's expected idling speed v, is determined during the prediction.

In order to determine a gradient resistance or a downgrade drive, an inclination value currently present in the vehicle and / or a gradient profile ascertainable from the digital map are or will be used.

In this case, a first tolerance band TB1 of a setpoint or set speed v _set , and a second tolerance band TB2 of a set speed V _{set are} specified as tolerance ranges with respect to the speed v of the vehicle, the two tolerance bands TB1, TB2 being within a third tolerance band TB3. In this case, the first tolerance band TB1 is encompassed by the second tolerance band TB2.

The idling operation of the vehicle is activated when it is determined from the expected course V _{E of} the speed v that the speed v of the vehicle, which is set upon activation of the idling mode, after a predetermined first minimum dwell time TD1 in the first tolerance band TB1 of the set speed v _setting will be located.

Alternatively, the idling operation of the vehicle is activated when the expected course V _{E of} the speed v, which is set upon activation of the idle mode, after a predetermined second minimum dwell time TD2, which is greater than the first minimum dwell time TD1, within the second tolerance band TB2 the setting speed v _set will be.

The activated idle mode of the vehicle is terminated when one of a plurality of predetermined termination conditions is met. In particular, it is envisaged to end the idling operation when the driver of the vehicle actuates the accelerator pedal or the brake pedal by a predeterminable minimum or if a current speed v of the vehicle is outside of the third tolerance band TB3.

In addition, it is provided that idling operation is terminated or not activated at all when at least one existing driver assistance function, a critical driving situation or a driving situation critical for the vehicle has been detected.

In idle driving situations, the idling mode of the vehicle is preferably activated for a predetermined minimum duration.

After terminating the idling mode, the speed v of the vehicle is adjusted with a desired acceleration of the constant-speed control or a driver assistance system then controlling in a detected critical driving situation with a cross-fading time, wherein the cross-fading time can be selected depending on the situation. That is, during the crossfade time, the vehicle is gradually accelerated from the current acceleration to the target acceleration to be set during the operational phase with regulatory intervention. This gives a smooth transition from idle operation, d. H. from the operational phase with no regulatory intervention to the operational phase with regulatory intervention, so that the transition is comfortable; d. H. without a jerk felt by the driver or by the vehicle occupants as unpleasant. The situation-dependent choice of the fade time means in particular that the fade time is chosen to be lower in dynamic situations than in less dynamic situations. For example, the fade time is reduced from a predetermined normal value when the driver of the vehicle changes the target speed or when a critical situation arises due to an obstacle appearing in front of the vehicle.

Particularly preferably, the driver of the vehicle before driving or during driving set whether he wants to use an idle operation of the vehicle to save fuel.

2 shows a second diagram 2 an expected time course G _{E of} a weighting factor G in the idling mode of the vehicle when the longitudinal dynamics control is operated in the operating mode distance during a distance control.

If the driver assistance system for longitudinal dynamics control is in the form of proximity control, the speed v of the vehicle is regulated as a function of a distance to a target vehicle ahead of the vehicle. The distance forms a control variable for the distance control.

If the vehicle drives with the distance control activated, then a prediction can be carried out become. In this case, an expected time profile G _{E of} a state variable, in particular an expected during idling operation weighting factor G, the so-called eco-weighting factor, determined, wherein the weighting factor G is a measure of stationarity of the distance control.

In this case, the weighting factor G based on various predetermined functions f1 (dt _error ), f2 (V _{rel_norm} ) a size, z. B. based on a function f1 (dt _error ) of a distance _error dt _error and based on a function f2 (v _{rel_norm} ) the normalized relative velocity V _{rel_norm} and / or based on functions of the speed v and / or the actual distance d _actual , are determined. Distance _error dt _error here is an actual target deviation of the time interval between the vehicle and the preceding vehicle to understand and under normalized relative velocity v _{rel_norm} is the quotient of a relative velocity v _rel between the vehicle and the vehicle in front and an actual speed v _Is the vehicle to understand.

Simple embodiments for determining the weighting factor G are, for example, the determination of the minimum from the functions of the distance _error dt _error and the normalized relative speed v _{rel_norm} : G = minimum (f1 (dt _error ), f2 (V _{rel_norm} )), or determining the product from the functions of the distance _error dt _error and the normalized relative speed v _{rel_norm} : G = f1 (dt _error ) · f2 (V _{rel_norm} ).

The weighting factor G is thus given as a function of the distance _error dt _error and as a function of the normalized relative speed V _{rel_norm} , wherein the weighting factor G can be specified such that it has a maximum of, for example, one, if the distance _error dt _error and the normalized relative speed V _{rel_norm} are nearly zero and with increasing amount of the _{pitch error} dt _error and / or with increasing amount of the normalized relative velocity V _{rel_norm} up to a predetermined minimum of z. B. decreases zero.

3 to 6 show possible examples of function _{curves of} the variables distance _error dt _error and relative speed V _{rel_norm} for determining the weighting factor G.

2 1 shows a first eco-tolerance band ETB1 of the weighting factor G, a second Eco-tolerance band ETB2 of the weighting factor G comprising the first Eco-tolerance band ETB1 and a third Eco-tolerance band ETB3 of the weighting factor G comprising the second Eco-tolerance band ETB2. The Eco-tolerance bands ETB1 , ETB2, ETB3 include the range of values between the maximum of the weighting factor G and in each case a predetermined limit G _min1 , G _min2 , G _min3 .

The region shown below in the figure as hatched area below the third eco-tolerance range ETB3 marks the value range of the weighting factor G lying outside the eco zone. If the prediction determines that the weighting factor G will assume a value outside the eco zone, then the idle mode is not activated, or it is, if it is already activated, terminated after the predetermined minimum duration.

The idling operation of the vehicle is then activated when it results from the expected course G _{E of} the weighting factor G that the vehicle will be located within the first eco-tolerance band ETB1 of the weighting factor G after a predetermined first minimum dwell time TD1.

Alternatively, the idling operation of the vehicle is activated when the vehicle is in a second Eco-tolerance band ETB2 of the weighting factor G after a second minimum dwell time TD2 '. The second minimum residence time TD2 'is greater than the first minimum residence time TD1'.

The idling operation of the vehicle is terminated when one of a plurality of predetermined termination conditions is met. In particular, it is provided to end the idling mode when the driver of the vehicle actuates the accelerator pedal or the brake pedal by a predeterminable minimum or when at least one existing driver assistance function detects a critical driving situation or a situation that becomes critical for the vehicle. In addition, it is provided that the idling operation is terminated when the determined weighting factor G leaves the third eco-tolerance band ETB3.

Analogous to the operating mode constant speed control, the transition from idle mode to mode with regulating intervention also takes place here in the operating mode distance-keeping sliding during a situation-dependent pre-fade time. The situation-dependent choice of the fade time means in particular that the fade time is chosen to be lower in dynamic situations than in less dynamic situations. For example, the fade time is reduced from a predetermined normal value when a critical situation is detected or when the target vehicle changes its speed.

In a further embodiment for activating the idling mode in the distance control mode, it is provided that in acceleration phases during the approach to a preceding vehicle, ie the target vehicle, a further expected time profile of the speed expected during idling operation is determined as state variable.

From the further expected time course of the speed, a time duration until reaching the speed of the target vehicle and then resulting distance between the vehicle and the target vehicle are determined.

In this embodiment, the idling mode is activated, if it results from the further expected time course of the speed that the vehicle will reach the speed of the target vehicle within a predeterminable first time interval and that then between the vehicle and the target vehicle resulting distance in a predeterminable first interval interval will be. That is, the idling is activated when a speed _matching period T _Dauer1 , which corresponds to the time period which the vehicle is expected to take to reach the speed of the target vehicle, will be within the first time interval, and that a speed _matching interval d _{Dauer1 corresponding} to the Distance that is likely to result between the vehicle and the target vehicle when the vehicle has reached the speed of the target vehicle will be within the first distance interval. The distance can be a spatial distance or a time interval, ie a time gap. The first time interval and the first distance interval are advantageously predefined as a function of the situation, in particular as a function of the setpoint distance to which the distance between the vehicle and target vehicle is to be adjusted, as well as the instantaneous speeds of the vehicle and the destination vehicle.

The first distance interval defines a tolerance range around the target distance that is to be maintained after the speed of the target vehicle has been reached. Specifying the first time interval ensures that idling will only be activated if it can remain active for a minimum period of time and is maximally long enough for the driver not to feel the approach process to be unreasonably long.

Furthermore, the activation of the idling mode is permitted only when the target vehicle is moving slower than the vehicle.

In addition, the activation is only permitted if a currently requested acceleration of the active driver assistance system for longitudinal dynamics control is greater than an instantaneous acceleration, which will occur during idling operation of the vehicle.

The idling operation of the vehicle is terminated when predetermined termination conditions are met. In particular, it is envisaged to end the idling mode when the driver of the vehicle actuates the accelerator pedal or the brake pedal by a predeterminable minimum, if at least one existing driver assistance function detects a critical driving situation or a driving situation becoming critical for the vehicle if the current speed of the vehicle is lower or equal to the speed of the target vehicle when the current distance between the vehicle and the target vehicle is less than the target distance, when the target vehicle is no longer detected, when the speed _matching time period T _{Dauer1 is} outside a predetermined second time interval, or if the speed _{matching distance} d _{Dauer1 is} out of range predetermined second interval interval is. The second time interval and the second distance interval are predefined in such a way that they include the first time interval or the first distance interval. As a result, a hysteresis for the switching of the operating phases is realized.

Analogous to the operating mode distance keeping, the transition from idle mode to mode with regulating intervention also takes place here in the mode approaching slipping during a cross-fading time, which, as explained in connection with the operating mode spacing, is specified depending on the situation.

A movement model for a pre-simulation is determined as a function of at least one air resistance, a rolling resistance and / or a pitch resistance, and / or a downgrade drive.

LIST OF REFERENCE NUMBERS

1

first diagram

2

second diagram

dt _error

spacing error

ETB1

first eco-tolerance band

ETb2

second eco-tolerance band

ETB3

third eco-tolerance band

f ₁

function

f ₂

function

G

weighting factor

G _E

expected course

G _min

minimum weighting factor

TB1

first tolerance band

TB2

second tolerance band

TB3

third tolerance band

TD1

first minimum length of stay

TD2

second minimum residence time

TD1 '

first minimum length of stay

TD2 '

second minimum residence time

v

speed

V _E

expected course

v _Set

setting speed

v _{rel_norm}

normalized relative speed

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010055373 [0002]
• EP 1475265 A2 [0003]

Claims (10)

Method for operating a vehicle having an adjustable speed-related and / or distance-related longitudinal dynamics control, wherein the longitudinal dynamics control comprises operating phases with regulatory intervention and operating phases without regulatory intervention and wherein an environment of the vehicle is detected and driving situations in which a fuel-saving regulation of a speed (v) is possible to be determined, characterized in that in operating phases with regulatory intervention, a prediction is carried out by an expected time course (V _E , G _E ) of a state variable (v, G) for the case depending on a driving distance ahead of the vehicle it is determined that at the current time a change from the operating phase with regulating intervention would take place in a freewheeling operation as an operating phase without regulating intervention, and that the freewheeling operation in dependence of the expected course (V _E , G _E ) and depending on ei ner mode of longitudinal dynamics control is activated. A method according to claim 1, characterized in that the vehicle is a vehicle with an internal combustion engine and that the freewheeling operation is an idling operation in which an operative connection between the internal combustion engine and drive wheels of the vehicle is disconnected. A method according to claim 1 or 2, characterized in that is used to determine the expected course (V _E , G _E ) of the state variable (v, G) is a slope of the underlying route. Method according to one of the preceding claims, characterized in that as expected course (V _E , G _E ) of the state variable an expected course (V _E ) of the speed (v) of the vehicle, which will set in the freewheeling operation, is determined. Method according to one of the preceding claims, characterized in that the freewheeling operation in dependence on the expected course (V _E , G _E ) of the state variable (V _E , G _E ) and depending on whether the longitudinal dynamics control in a mode constant speed control, distance during a distance control or approaching a preceding target vehicle during a distance control is activated. A method according to claim 5, characterized in that during operation of the longitudinal dynamics control in the constant speed control mode - an expected in coasting operation (V _E ) of the speed (v) of the vehicle is determined as the expected course of the state variable, - a first tolerance band (TB1) a Setting speed (v _set ) and a second tolerance band (TB2) of the setting speed (v _set ) encompassing the first tolerance band (TB1) are activated and - the freewheeling mode is activated if the speed (v) after a predeterminable first minimum dwell time (TD1) in the first tolerance band (TB 1) will be the set speed (v _set) or when the speed (v) at least after a predetermined second minimum retention time (TD2) which is greater than the first Mindestesverweildauer (TB2) is in the second tolerance band (TB2) of the setting speed (v _set ) will be. A method according to claim 5 or 6, characterized in that during operation of the longitudinal dynamics control in the operating mode spacing during the distance control an expected in free-running operation curve (G _E ) of a weighting factor (G) is determined as the expected course of the state variable, wherein the weighting factor (G) is a measure of the stationarity of the distance control, and that the freewheeling operation is activated at a high stationarity of the distance control, which is recognized on the basis of the course (G _E ) of the weighting factor (G). Method according to Claim 7, characterized in that - a first eco-tolerance band (ETB1) of the weighting factor (G) and a second eco-tolerance band (ETB2) of the weighting factor (G) comprising the first eco-tolerance band (ETB1) are predefined, the eco-tolerance bands (ETB1, ETB2) each comprise the range of values between a maximum of the weighting factor (G) and a predetermined limit (G _min1 , G _min2 ), - and that the freewheeling mode of the vehicle is activated if the expected course ( G _E ) of the weighting factor (G) reveals that the vehicle will be located within the first eco-tolerance band (ETB1) of the weighting factor (G) after a predetermined first minimum dwell time (TD1 ') or after a second minimum dwell time (TD2'). which is greater than the first minimum dwell time (TD1 '), will be in the second eco-tolerance band (ETB2) of the weighting factor (G). Method according to one of claims 5 to 8, characterized in that during operation of the longitudinal dynamics control in the approaching mode during the distance control - an expected course in free-running operation (V _E ) of the speed (v) of the vehicle is determined as the expected course of the state variable, and the freewheeling operation is activated, if from the expected course (V _E ) of the speed (v) indicates that the vehicle will reach the speed of a preceding target vehicle within a predeterminable time interval and that upon reaching the speed of the preceding target vehicle, the distance between the vehicle and the preceding destination vehicle will be within a predeterminable distance interval. Method according to one of the preceding claims, characterized in that the freewheeling operation is aborted when at least one predetermined termination conditions is met, wherein the transition from the freewheeling operation to the operating phase with regulating intervention takes place slidably and is performed within a situation-dependent predefinable fade time.

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