DE102018222227A1 - Procedure for adjusting a vehicle speed - Google Patents

Abstract

The invention relates to a method for adapting a vehicle speed (20) of a vehicle to a curve (14). In a step (S1), a curvature curve of a curve curve (14) lying ahead on a route (10) is determined. In a further step (S2), a vehicle speed curve (22, 22 ') for driving on the curve curve (14) lying ahead is determined as a function of the determined curve curve. In a further step (S3), the vehicle is controlled to adapt a current vehicle speed (21) to the defined vehicle speed curve (22, 22 '). The invention also relates to a control device which is set up to carry out the method.

Description

Technical field

The present invention relates to a method for adapting a vehicle speed to a curve. Furthermore, the present invention relates to a control device which is set up to carry out the method.

State of the art

With vehicle sensors provided on a vehicle, moving vehicles can be detected in a section of road ahead. According to the DE 10 2012 219 850 A1 A section of the route ahead is monitored with such vehicle sensors in order to obtain information about an obstacle to driving or about a possible free journey in the section of the route ahead.

Presentation of the invention

The present invention relates to a method for adapting a vehicle speed of a vehicle to a curve. The course of the curve can have a curved section of a route. The curved section can for example run at least in sections along a curve or a roundabout.

As a step, the method comprises determining a curvature course of a curve course lying ahead on a route. The curvature course can have a course of a route curvature along the route. The section curvature can be formed by a reciprocal curve radius present in a curve. The route ahead in the direction of travel of a vehicle can also be referred to as the horizon or forecast horizon. In the course of the method, for example, a route up to two kilometers long ahead can be considered in an efficient manner to determine a curvature course. The vehicle can be a commercial vehicle, for example a semi-trailer. The vehicle can have a trailer. Likewise, the vehicle can be a passenger car or another vehicle.

As a further step, the method comprises defining a vehicle speed curve for driving on the curve curve ahead as a function of the determined curve curve. When determining the vehicle speed profile, centrifugal forces acting on the vehicle when driving on the curve profile can be taken into account. The vehicle speed curve can have at least one fixed vehicle speed. The curvature curve and the vehicle speed curve can be related by a functional connection. Vehicle speeds as a function value of the curvature curve can be defined as a function of location or time. Vehicle speeds can thus be defined as a speed path along the route ahead or along the curvature.

The defined vehicle speed curve can define the speed to be driven before the curve, ie on a straight route. The defined vehicle speed curve can then further define the speed to be driven in the curve curve. The defined vehicle speed curve can also define the speed to be driven after the curve, ie again on a straight route.

As a further step, the method comprises controlling the vehicle, in particular the drive of the vehicle, to adapt a current vehicle speed to the defined vehicle speed curve. In particular, the method includes automatic control of the vehicle. Controlling the vehicle, in particular the vehicle drive, can include changing an operating state or selecting an operating mode of a drive machine or an engine of the vehicle. The motor can basically be an internal combustion engine, an electric motor and / or another motor. For example, the vehicle can be controlled in such a way that the vehicle rolls or sails when starting off, when driving through and / or when driving after a curve. Controlling the vehicle may include changing gears or changing a gear ratio. Controlling the vehicle can thus have a reduction and / or an increase in a drive torque provided by a drive machine in order to decrease and / or increase the vehicle speed. The control of the vehicle drive can automatically intervene in a free travel of the vehicle. A set cruise control speed of the vehicle can be undercut.

In the context of the invention, an automated speed reduction can be carried out before and during cornering. Different thrust phases of a drive machine can be used in a fuel-efficient manner before and during cornering. When driving off and when cornering, fuel-efficient operation of the vehicle and on the other hand, safe driving can be achieved. Automated braking of the vehicle can be advantageous since a driver often cannot fully see distances up to a curve and the course of the curve as such from his restricted field of vision. A resulting fuel-inefficient braking behavior of a driver can be avoided with the present invention. Closure of vehicle brakes can also advantageously be reduced in this way.

In one embodiment of the method, the step of determining the curvature has a map-based determination of the preceding curve. The curve course ahead can be derived from map data, which may have a course ahead of the route traveled by the vehicle. The curve shape along the curve shape can be determined from the derived curve shape by local differentiation. The step of determining the curvature curve can be carried out using a vehicle navigation system, which can provide a current vehicle position and map data. The data used can first be checked for plausibility before use. For example, outliers can be identified in the data.

In a further embodiment of the method, the step of determining the curvature has a sensor-based detection of the curve curve ahead. As an alternative or in addition to a map-based determination of the curve shape lying ahead, it can be derived from sensor data. For this purpose, sensors can be arranged on the vehicle for detecting a route ahead. The sensor system can be camera-based sensor system, wherein at least one camera arranged on the vehicle can capture a camera image of the route ahead. With camera images and / or map data, a route can thus be recorded in advance. The camera images and / or the map data can therefore act as preview data. The curve curve ahead can be extracted from a camera image by means of feature recognition of contours of the curve curve or of road markings. As described, the curve shape can then be determined from the extracted curve shape.

A sensor-based detection of the curve shape lying ahead can also be carried out to check or check the plausibility of a curve-based curve shape. An actual route deviating from map data can thus be recognized during the journey and taken into account when determining the curvature course. A temporary curve shape, which can be a non-mapped curve shape, can thus also be determined. The temporary course of the curve can, for example, be a route along a construction site.

In a further embodiment of the method, the vehicle speed curve is a position-based curve. Alternatively, the vehicle speed curve can be a time-based curve. The position-based course can be based on a relative position or distance of the vehicle from the curve course. The time-based course can be based on a time period of the vehicle until it enters the curve or until the corner is entered. A position-based speed profile can also take into account a gradient or a topography along the curve profile. Changes in altitude, which result in going up or down a hill along the curve, can also be taken into account when controlling the vehicle drive or when setting the speed.

In the context of this embodiment, the method can have, as further steps, determining a current vehicle position and controlling the speed of the vehicle taking into account the current vehicle position. The current vehicle position can be determined using a satellite positioning system. For example, a GNSS antenna can be arranged on the vehicle in order to determine the current vehicle position from GNSS satellite signals. Controlling the vehicle can include continuously adapting a current vehicle speed as a function of the current vehicle position. If the current vehicle position is known, the speed that corresponds to the current position can be determined from the position-based speed profile, for example.

In a further embodiment of the method, the vehicle speed profile has a speed minimum at or along a maximum curvature of the curve profile. In other words, the vehicle speed curve can have a minimum speed for limiting a vehicle speed at the maximum curvature of the curve curve. The minimum or minimum speed can thus determine the lowest speed when driving along the curve. The speed minimum can determine the speed at which the Vehicle can safely drive the maximum curvature of the curve, that is to say without leaving a lane, for example, due to centrifugal forces acting on it.

In the context of this embodiment, the step of controlling the vehicle comprises braking the vehicle to the minimum speed. Braking can take place actively or passively. Active braking can in principle be carried out with any vehicle system for braking or decelerating the vehicle. Such braking can be brought about by a vehicle brake or by a vehicle drive. A vehicle brake can be an engine brake, a service brake or a service brake of the vehicle. Passive braking can be brought about, for example, by air resistance when the vehicle is sailing or due to a downhill force when driving the vehicle uphill. When sailing, a prime mover of the vehicle can be switched off and disconnected from a drive train of the vehicle.

The steps of determining the curvature course of the curve ahead and establishing the vehicle speed course or setting the speed minimum can be carried out repeatedly or iteratively. The vehicle speed curve can thus be checked and continuously adapted to a curvature curve that can currently be determined.

In a further embodiment of the method, braking the vehicle to the minimum speed comprises operating the vehicle in overrun mode. In the overrun mode, an engine brake can brake the vehicle and thus reduce the vehicle speed. The driving condition can be referred to as overrun mode or push mode, in which the motor is dragged through the vehicle, that is to say is kept rotating, when the force connection is not disconnected (e.g. when the clutch is not depressed). The fuel supply can be interrupted. For this purpose, an electric motor can be operated in a generator mode, for example. A drag power of a vehicle engine can thus be used in an advantageous and energy-efficient manner to brake the vehicle. Applying a service brake of the vehicle may not be at least partially necessary to brake the vehicle. The wear of the service brake can thus be reduced in an advantageous manner.

In a further embodiment of the method, braking the vehicle to the minimum speed comprises actuating a braking device of the vehicle. In addition or as an alternative to operating the vehicle in an overrun mode to brake the vehicle, a wheel brake or a useful brake can be actuated.

In a further embodiment of the method, the step of determining the vehicle speed curve for driving on the curve curve ahead is carried out taking into account a speed specification that is independent of the curve curve. The independent speed specification can be a speed limit before, along or after the curve. The speed limit can have a lower speed than a speed minimum which is defined for a maximum curvature of the curve. The speed curve can therefore follow a curve-independent speed specification at least in sections. A speed limit that overlaps with a curvature-dependent speed specification can thus be given priority when driving on a curve.

The speed limit can be specified by a traffic sign along the route. The traffic sign can contain a speed specification. The traffic sign can also be a place sign, for example, which indicates a speed limit. The traffic sign can be mapped in the map data, whereby the speed limit can be derived from the map data. Alternatively or additionally, the traffic sign can also be recognized in a camera image, as a result of which the speed limit can be derived from the camera image.

In a further embodiment of the method, the step of determining the vehicle speed curve for driving on the curve curve ahead is carried out taking into account at least one vehicle operating state and / or at least one roadway state. The vehicle operating state can have at least one of a mass, a driving resistance, a drag curve and an autonomy level of the vehicle or a trailer attached to the vehicle. The roadway condition can have at least one of a roadway width, a roadway longitudinal incline, a roadway cross slope, a roadway ripple, a roadway roughness and a degree of soiling of a roadway. The vehicle operating state and / or the state of the roadway can be used to determine the minimum speed when driving through the curve. Thus, in addition to the Curvature course also parameters external to the vehicle for safe cornering are taken into account.

In a further embodiment of the method, the defined vehicle speed profile has a continuously differentiable profile. The continuously differentiable course can in principle be any functional relationship of a higher order between the vehicle speed and the vehicle position. As an alternative or in addition, the defined vehicle speed profile can have a sectionally linear vehicle speed profile. The continuously differentiable course can be derived from a sectionally linear vehicle speed course. The derivation of the continuously differentiable course can be determined by an interpolation, at least in some areas, of the sectionally linear vehicle speed course. The continuously differentiable course allows a particularly good control or regulation of the vehicle speed.

After driving on the curve section, the vehicle speed can again be specified or set by a driver. This can take place when exiting or after exiting a curve, the vehicle speed then being able to be freely selected by the driver again in principle in free travel.

The present invention also relates to a control device which is set up to carry out the method according to one of the embodiments described above.

Figure list

• 1 shows a vehicle speed curve for explaining the method for adapting a vehicle speed to a curve shape according to an embodiment of the present invention.
• 2nd shows a flowchart with steps of the method for adapting a vehicle speed to a curve shape according to an embodiment of the present invention.

Detailed description of embodiments

In 1 are defined vehicle speed profiles 22 , 22 ' shown. The vehicle speed curves 22 , 22 ' are shown in a diagram, the abscissa of the route 10 and its ordinate is the vehicle speed 20 a vehicle (not shown). The vehicle is at a current vehicle position 11 in a first straight route 13 in front of you on the route 10 ahead curve 14 . The course of the curve 14 is by starting a curve 16 and a curve end 17th limited. After the curve 14 a second straight route follows 13 ' .

In a first step S1 of the method of the present embodiment, the curvature (not shown) along the curve portion ahead 14 of the vehicle. First of all, the curve in front of the vehicle 14 with associated curve radii based on map data, as described above. From the curve 14 the curvature curve is derived.

In a subsequent step S2 depending on the step S1 determined curvature curve a vehicle speed curve 22 fixed. First of all, there is a minimum speed 25th at the maximum point of curvature of the curve taking into account the maximum amount of curvature 15 , from a vehicle-external speed limit, from a road condition and / or from a vehicle operating state, as described above. Based on the determined minimum speed 25th first a sectionally linear vehicle speed curve 22 ' certainly. In a first section 2nd shows the sectionally linear vehicle speed curve 22 ' along the first straight route 13 until the beginning of the curve 16 a constant vehicle speed 20 , for example the current driving speed of the vehicle. In a second phase 4th shows the sectionally linear vehicle speed curve 22 ' about the beginning of the curve 16 down to the curve section 14 into it a linearly decreasing vehicle speed 20 on. The beginning of the linearly declining course is set in such a way that a consumption-optimized braking to the minimum speed 25th is made possible.

In a third phase 6 shows the sectionally linear vehicle speed curve 22 ' in the remaining curve 14 until the end of the curve 17th a constant speed, namely the determined minimum speed 25th on. In a fourth phase 8th shows the sectionally linear vehicle speed curve 22 ' about the end of the curve 17th out into the second straight course 13 ' into it a linearly increasing vehicle speed 20 on. The vehicle speed in this section can increase up to the speed of the vehicle after the curve. In a fifth phase 2 ' shows the sectionally linear vehicle speed curve 22 ' along the second straight route 13 ' again a constant vehicle speed 20 , namely the Vehicle speed after exiting the curve.

Based on the sectionally linear vehicle speed curve 22 ' becomes a continuously differentiable vehicle speed curve 22 fixed. The continuously differentiable vehicle speed curve 22 differs from the sectionally linear vehicle speed curve 22 ' in that it is at the transition points between the linear profile sections 2nd , 4th , 6 , 8th , 2 ' has continuously differentiable transitions. In the middle of the linear sections 2nd , 4th , 6 , 8th , 2 ' the continuously differentiable vehicle speed curve is correct 22 coincides with the linear portions in the present embodiment.

In one step S3 the speed of the vehicle is controlled so that this in step S2 steadily differentiable speed curve 22 follows. In a maximum curvature 15 of the curve section 14 is the vehicle speed 20 essentially equal to the minimum speed 25th . For braking the vehicle to the minimum speed 25th the vehicle is operated in overrun mode as described above.

In a fourth step S4 becomes the current vehicle speed 21st checked for a discrepancy between the current speed 21st and to determine the target speed defined in S2. Based on the comparison, the step S3 performed again to adjust the speed of the vehicle to the target speed. The steps S3 and S4 are repeated continuously to point to the curve 14 by continuously adjusting the vehicle speed 20 to respond reliably.

Reference list

2nd

first course section

2 '

fifth phase

4th

second course section

6

third course section

8th

fourth phase

10th

Route

11

current vehicle position

13

first straight route

13 '

second straight route

14

Curve shape

15

Maximum curvature

16

Beginning of curve

17th

End of curve

20

Vehicle speed

21

current vehicle speed

22

Constantly differentiable vehicle speed curve

22 '

linear vehicle speed curve

25th

Minimum speed

S1

Determination of curvature

S2

Definition of vehicle speed curve

S3

Control vehicle

S4

Check vehicle speed

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102012219850 A1 [0002]

Claims (10)

Method for adapting a vehicle speed (20) of a vehicle to a curve (14), comprising the steps Determining (S1) a curvature of a curve (14) lying ahead on a route (10), Determining (S2) a vehicle speed curve (22, 22 ') for driving on the curve curve (14) lying ahead as a function of the determined curve curve and Control (S3) of the vehicle to adapt a current vehicle speed (21) to the defined vehicle speed curve (22, 22 '). Procedure according to Claim 1 , wherein the step of determining (S1) the curvature has a map-based determination and / or a sensor-based detection of the preceding curve (14). Method according to one of the preceding claims, wherein the vehicle speed curve (22, 22 ') is a position-based curve and the method as further steps, determining a current vehicle position (11) and controlling (S3) the vehicle, taking into account the current vehicle position (11) having. Method according to one of the preceding claims, wherein the vehicle speed profile (22, 22 ') has a speed minimum (25) at a maximum curvature (15) of the curve profile (14) and the step of controlling (S3) the vehicle braking the vehicle to the speed minimum (25). Procedure according to Claim 4 , wherein braking the vehicle to the minimum speed (25) comprises operating the vehicle in overrun mode. Procedure according to Claim 4 or 5 wherein braking the vehicle to the minimum speed (25) comprises actuating a braking device of the vehicle. Method according to one of the preceding claims, wherein the step of determining (S2) the vehicle speed profile (22, 22 ') for driving on the preceding curve profile (14) is carried out taking into account a speed specification which is independent of the curvature profile. Method according to one of the preceding claims, wherein the step of determining (S2) the vehicle speed profile (22, 22 ') for driving on the preceding curve profile (14) is carried out taking into account at least one vehicle operating state and / or at least one road state. Method according to one of the preceding claims, wherein the defined vehicle speed profile (22) has a continuously differentiable profile (22). Control device which is set up to carry out the method according to one of the Claims 1 to 9 to execute.

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