Method for limiting vehicle speed when traveling along a curve

Abstract

The present invention relates to a method for limiting the travel speed (v) of a vehicle when traveling around a curve (K), comprising the steps of: calculating the progression of the curvature (κ) of a road section ahead of the vehicle using a digital map; calculating the progression of an allowable curve speed (v) depending on the progression of the curvature (κ) and on the physical load limits of the vehicle; controlling the vehicle when traveling around the curve (K) so as not to exceed the calculated allowable curve speed (v) and controlling the vehicle so that the curvature (κ) does not exceed a specified curvature limit value (κ lim ) are identified as curved sections by evaluating the course of the curvature (κ), local curvature maxima are identified on the identified curved sections, and for each local curvature maxima, the curvature (κ) and the permissible lateral acceleration (a querzul The allowable curve speed (v) is calculated depending on

Description

[Technical field]

[0001] The present invention relates to a method for limiting the driving speed of a vehicle when driving around a curve according to the preamble of claim 1 . [Background technology]

[0002] There are many approaches in the literature for determining the optimal location of the recommended speed when driving around a curve, but they are often insufficient or do not reflect reality well. Complex curve shapes are often considered with only one speed limit. As a result, automatic and predictive speed control systems often adjust the speed at the wrong time (or in the wrong place) when driving around a curve.

[0003] DE 10 2006 006 365 A1 describes a device and a method for controlling the longitudinal movement of a vehicle, in which surrounding and / or section data are detected and used as a basis for influencing the vehicle depending on the position of the vehicle on the route, the route curvature profile and the maximum speed profile dependent thereon are predetermined, this maximum speed profile is corrected to adapt to the physical load limits of the vehicle and a speed limit is implemented on the basis of the corrected maximum speed profile.

[0004] DE 10 2009 023 489 A1 describes a method and a device for controlling the speed of a vehicle. On the basis of digital map data, a maximum speed curve is calculated that depends on the road section ahead. Furthermore, the speed of the vehicle is limited according to the calculated maximum speed curve in such a way that, even if the speed is greater than the speed of the maximum speed curve, it does not fall below a specified speed limit. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide an improved method for limiting the travel speed of a vehicle when negotiating a curve. [Means for solving the problem]

[0006] This object is achieved in accordance with the invention by a method for limiting the travel speed of a vehicle when negotiating a curve as claimed in claim 1.

[0007] Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0008] In the method according to the invention for limiting the travelling speed of a vehicle when going around a curve, the course of the curvature of the road section ahead of the vehicle is determined, in particular by means of a digital map and / or by means of data from a sensor system for surrounding detection, the course of the permissible curve speed is determined as a function of this course of curvature and the physical load limits of the vehicle, and the vehicle is controlled when going around a curve in such a way that the determined permissible curve speed is not exceeded. According to the invention, a road section whose curvature is greater than a specified curvature limit value is identified as a curve section by evaluating the curvature course, local curvature maxima are identified on this identified curve section, and if several local curvature maxima are identified on the curve section, the permissible curve speed is calculated for each local curvature maxima as a function of the curvature and the permissible lateral acceleration.

[0009] The invention described herein sets an associated curve speed, and optionally multiple speed limits, at an associated location within the curve, allowing the speed control system to function accurately and reliably.

[0010] In one embodiment, the permissible lateral acceleration is specified as a function of the curvature, particularly as a characteristic curve or look-up table.

[0011] In one embodiment, the identified curve interval is divided into a number of adjacent curve sections, the boundaries between adjacent curve sections being formed by local curvature maxima.

[0012] In one embodiment, the deviation between the permissible curve speeds at the start and end of each curve section is calculated, and if the calculated deviation exceeds a specified speed threshold, at least one further permissible curve speed is calculated on the respective curve section by interpolation, in particular linear interpolation, based on the permissible curve speeds at the start and end of the respective curve section.

[0013] In one embodiment, the greater the calculated deviation between the permissible curve speeds at the start and end of the respective curve section, the greater the number of calculated further permissible curve speeds is selected.

[0014] In one embodiment, the respective position for the at least one further permissible curve speed is determined by determining the associated curvature and calculating the exact position of the further speed limit by linear interpolation between the two curvature values.

[0015] In one embodiment, a characteristic curve or look-up table is used to calculate the allowable lateral acceleration depending on the speed.

[0016] In one embodiment, a retroactive check for the need for an additional speed limit is performed based on the acceleration process, and if the acceleration required to reach the speed limit at the subsequent curvature maximum exceeds a specified or specifiable, adjustable acceleration limit, the additional speed limit is omitted (removed).

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Brief description of the drawings]

[0018] [Figure 1] FIG. [Diagram 2] FIG. 2 is a schematic diagram of a curve divided into curve sections. [Diagram 3] FIG. 4 is a schematic diagram of a characteristic curve of the permissible lateral acceleration depending on the curve curvature. [Figure 4]FIG. 2 is a schematic diagram of a curve divided into curve sections. [Diagram 5] FIG. 4 is a schematic diagram of a characteristic curve of the permissible lateral acceleration as a function of speed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In all the figures, corresponding parts are provided with the same reference numerals.

[0020] The present invention relates to a method for limiting the driving speed of a vehicle when navigating a curve K.

[0021] According to the invention, in particular with the aid of a digital map, the curvature profile (change) of the road section ahead of the vehicle is calculated. The evaluation of the curvature profile determines whether the curvature κ (also called the curve curvature κ) falls within a specified (predetermined) curvature limit value κ lim A road section with a curvature κ greater than k is identified as a curve section. The curvature κ is understood here to be the amount (magnitude) of curvature, i.e. any sign indicating the direction of the curvature, i.e. whether the curvature is to the left or to the right, is not taken into account. In the identified curve section, local curvature maxima k2, k6, k8, k12 are identified. For each local maximum, an allowable curve speed v is calculated depending on the curvature κ and the allowable lateral acceleration (as a function of ). When driving around the curve K, the vehicle is controlled so as not to exceed the calculated allowable curve speed v.

[0022] FIG. 1 is a schematic diagram of the curve.

[0023] A curve K is divided into regions k1 to k16 having a curve entrance KE and a curve exit KA, and a curvature threshold κ lim In this case, in FIG. 1, the curve entrance KE has a curvature κ larger than the curvature threshold κ lim In FIG. 1, the curve exit KA is the area k0 before the curve K with a curvature κ smaller than the curvature threshold κ lim The region k14 behind the curve K has a curvature κ smaller than

[0024] FIG. 2 is a schematic diagram of a curve K divided into curve sections KS1 to KS5.

[0025] Between the curve entrance KE and the curve exit KA, the curve K can be further divided into curve sections KS1 to KS5, each having a section start and a section end.

[0026] The start section KS1 starts at the curve entrance KE, i.e. in region k0 in Figure 2, and extends to the subsequent curve curvature maximum, i.e. in region k2 in Figure 2. The end section KS5 ends at the curve exit, i.e. in region k14 in Figure 2, and starts at the last curvature maximum, i.e. in region k12 in Figure 2.

[0027] One or more intermediate sections KS2 to KS4 may be located between the start section KS1 and the end section KS5, each intermediate section KS2 to KS4 starting at a curvature maximum, i.e., region k2, k6, k8 in FIG. 2, respectively, and extending to a subsequent curvature maximum, i.e., region k6, k8, k12 in FIG. 2.

[0028] In alternative embodiments, a different number of curve sections KS1 to KSn may be provided.

[0029] This allows a plurality of curve sections KS1 to KSn to be formed in the same direction.

[0030] In one embodiment, a speed limit v zul is not given.

[0031] The first speed limit in the first curve section KS1 (region k0 to k2) may be at the location of the first curvature maximum (region k2) or an additional speed limit v zul It may be located at the position.

[0032] Within curve sections KS1 to KSn there may be at least one curvature maximum, but up to two curvature maximums.

[0033] At all curvature maxima, the speed limit v zul can be calculated based on the following formula:

[0034]

number

[0035] Permissible lateral acceleration a querzul (κ) can be used as a characteristic curve KL1 that depends on the curve curvature κ.

[0036] FIG. 3 is a schematic diagram of the characteristic curve KL1.

[0037] Within the characteristic curve KL1, linear interpolation must be performed between its reference points (grid points).

[0038] For example, the characteristic curve KL1 may have the following reference points:

[0039] [Table 1]

[0040] Speed ​​limit at maximum curvature v zul can be determined as follows:

[0041] If the curve section KS1 to KSn under consideration starts with a curvature maximum, the required acceleration falls below a specified or specifiable adjustable limit value (i.e. the speed limit v of the subsequent maximum value zul is quantitatively close to the preceding maximum), the subsequent curvature maximum should be omitted.

[0042] If the following maximum speed limit v zul is omitted.

[0043]

number

[0044] Speed ​​limit at curve exit KA v zul (Legal speed limit v legal The position of the

[0045] If the curve section KS1 to KSn under consideration ends at the curve end point KE (i.e. the curvature κ is below the specified or adjustable curvature limit), then the curvature κ is greater than the current speed limit v zul A position before the curve end point KE corresponding to the desired curve end point KE is calculated. This position is the desired curve end point KE. This position is calculated as follows:

[0046]

number

[0047] Curve curvature κ and legal speed limit v legal The relationship may be stored in a characteristic curve or a look-up table.

[0048]

number

[0049] Permissible lateral acceleration a querzul and the legal speed limit v legal The relationship may be stored in a characteristic curve or a look-up table.

[0050]

number

[0051] The curve end point KE, in this application, is, for example, a specific bit width, for example, 8 bits, and the highest value of the numerical range, for example, 255, which can indicate a state in which data is unavailable. At the curve end point KE, the legal speed limit v legal You can then drive again.

[0052] The additional speed limits within the individual curve sections KS1 to KSn can be calculated as follows:

[0053] The absolute velocity difference Δv between the start of the curve section and the end of the curve section is considered, and the velocity difference parameter v P1 , v P2 is compared to.

[0054] In case a), Δv <v P1 In this case, no additional speed limit is set.

[0055] In case b), Δv>v P1 In this case, an additional speed limit is set at the position corresponding to Δv / 2.

[0056] In case c), Δv>v P2 In this case, two additional speed limits are set at positions corresponding to Δv / 3 and 2Δv / 3.

[0057] FIG. 4 is a schematic diagram of a curve K divided into curve sections KS1 to KS3.

[0058] The start section KS1 starts at the curve entrance KE, i.e. in region k0 in Figure 4, and extends to the following curve curvature maximum, i.e. in region k8 in Figure 4. The end section KS3 ends at the curve exit KA, i.e. in region k14 in Figure 4, and starts at the last curvature maximum, i.e. in region k12 in Figure 4.

[0059] The intermediate section KS2 is located between the start section KS1 and the end section KS3. The intermediate section KS2 starts at the curve curvature maximum, i.e. the region k8 in FIG. 4, and extends to the following curve curvature maximum, i.e. the region k12 in FIG. 4. At the start of the start section KS1, a speed limit of 100 km / h is set. At the end of the start section KS1, a speed limit of 67 km / h is set. The absolute speed difference Δv between the start of the start section KS1 and the end of the start section KS1 is 33 km / h. In the illustrated example, the speed difference parameter v P1 ,v P2 is set as follows: v P2 =30km / h v P1 =20km / h

[0060] The first additional speed limit is v ACS1 =100-33 / 3=89km / h. The second additional speed limit is v ACS2 =100-2 * 33 / 3=78km / h.

[0061] Furthermore, for the additional speed limit, an associated position can be determined, for which reason an associated curve curvature can be determined.

[0062] The exact position of the additional speed limit is calculated, for example, by linear interpolation between the two curvature values. The permissible lateral acceleration a depends on the speed v. querzul A characteristic curve for calculating the

[0063] FIG. 5 is a schematic diagram of the characteristic curve KL2.

[0064] For example, the characteristic curve KL2 may have the following reference points:

[0065] [Table 2]

[0066]

number

[0067] A follow-up check (retrospective check) on the need for additional speed limits can be carried out based on the acceleration process. Additional speed limits can be, for example, the speed limit v at a subsequent curvature maximum. zul If the acceleration required to reach exceeds a specified or specifiable, adjustable acceleration limit (i.e., if the additional speed limit differs too much from the subsequent maximum value and is therefore invalid), it is omitted.

[0068] The additional speed limit is omitted, for example, in the following cases:

[0069]

number

[0070] Acceleration limit a limit1 and a limit2 may be predetermined to be different or the same. [Prior art documents] [Patent documents]

[0071] [Patent Document 1] DE 102006006365 A1 [Patent Document 2] DE 102009023489

Claims

1. 1. A method for limiting a driving speed (v) of a vehicle when traveling around a curve (K), comprising the steps of: calculating a progression of a curvature (κ) of a road section ahead of the vehicle; calculating a progression of an allowable curve speed (v) depending on the progression of the curvature (κ) and on the physical load limits of the vehicle; and controlling the vehicle when traveling around the curve (K) in such a way that the calculated allowable curve speed (v) is not exceeded, - the curvature (κ) is less than the specified curvature limit (κ ｌｉｍ ) is identified as a curved section by evaluating the course of the curvature (κ), - local curvature maxima are identified on the identified curve section, - if several local curvature maxima are identified on the curve section, for each local curvature maxima, the curvature (κ) and the permissible lateral acceleration (a ｑｕｅｒｚｕｌ The allowable curve speed (v) is calculated depending on - the identified curve segment is divided into a number of adjacent curve sections (KS1 to KSn) having at least one end overlapping with each other, the overlapping being formed by the local curvature maxima; A method comprising:

2. The allowable lateral acceleration (a ｑｕｅｒｚｕｌ ) is specified depending on the curvature (κ) 2. The method according to claim 1 .

3. The allowable lateral acceleration (a ｑｕｅｒｚｕｌ ) is designated as a characteristic curve (KL1) or a look-up table depending on the curvature (κ) 3. The method according to claim 2 .

4. A deviation between the permissible curve speeds (v) at the start and end of each of the curve sections (KS1 to KSn) is calculated, and if the calculated deviation exceeds a specified speed threshold, at least one further permissible curve speed (v) is calculated on each of the curve sections (KS1 to KSn) by interpolation based on the permissible curve speeds (v) at the start and end of each of the curve sections (KS1 to KSn). The method according to any one of claims 1 to 3, characterized in that

5. The interpolation is performed as a linear interpolation.

5. The method according to claim 4 .

6. The greater the calculated deviation between the permissible curve speeds (v) at the start and end of each curve section (KS1 to KSn), the greater the number of calculated further permissible curve speeds (v) is selected.

5. The method according to claim 4 .

7. The respective position for the at least one further permissible curve speed (v) is determined by determining the associated curvature (κ) and calculating the exact position of the additional speed limit by linear interpolation between the two curvature values.

5. The method according to claim 4 .

8. The characteristic curve (KL2) or the look-up table determines the permissible lateral acceleration (a) as a function of the permissible curve speed (v). ｑｕｅｒｚｕｌ ) is used to calculate 8. The method according to claim 7 .

9. A retroactive check for the necessity of the additional speed limit is performed based on an acceleration process, and if in the retroactive check it is determined that the acceleration required to reach the speed limit at the subsequent curvature maximum from the additional speed limit exceeds a predetermined acceleration value, the additional speed limit is omitted.

8. The method according to claim 7 .

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