Method and device for scanning a location

Abstract

A method for scanning a location, including the following features: an ego velocity is measured at predefined points in time, and a counter is incremented as a function of the ego velocity, and as soon as the counter reaches a predefined threshold value, the location is determined.

Claims

1. A method for scanning a location, comprising: measuring an ego velocity at predefined points in time; incrementing a counter as a function of the ego velocity; as soon as the counter reaches a predefined threshold value, determining the location; determining a weight factor as a function of the ego velocity, wherein the counter is incremented as a function of the weight factor; allocating a velocity interval from among a plurality of predefined velocity intervals to the ego velocity, which includes the ego velocity; and based on the allocated velocity interval, the weight factor is read out from a lookup table.

2. The method s recited in claim 1, wherein the respective location is transmitted via an air interface, and the lookup table is configured via the air interface.

3. The method as recited in claim 1, wherein the points in time are equidistant, and the counter is incremented by the weight factor.

4. The method as recited in claim 1, further comprising: forming a product from the weight factor and a time difference between the respective point in time in relation to a directly past point in time from among the points in time; wherein the counter is incremented by the product.

5. The method as recited in claim 1, wherein the location is determined with the aid of a global navigation satellite system.

6. A non-transitory machine-readable memory medium on which is stored a computer program for scanning a location, the computer program, when executed by a computer, causing the computer to perform: measuring an ego velocity at predefined points in time; incrementing a counter as a function of the ego velocity; and as soon as the counter reaches a predefined threshold value, determining the location, determining a weight factor as a function of the ego velocity, wherein the counter is incremented as a function of the weight factor; allocating a velocity interval from among a plurality of predefined velocity intervals to the ego velocity, which includes the ego velocity; and based on the allocated velocity interval, the weight factor is read out from a lookup table.

7. A telematics control unit for a motor vehicle, configured to scan a location, the telematics control unit configured to: measuring an ego velocity at predefined points in time; incrementing a counter as a function of the ego velocity; and as soon as the counter reaches a predefined threshold value, determining the location, determining a weight factor as a function of the ego velocity, wherein the counter is incremented as a function of the weight factor; allocating a velocity interval from among a plurality of predefined velocity intervals to the ego velocity, which includes the ego velocity; and based on the allocated velocity interval, the weight factor is read out from a lookup table.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are shown in the figures and are described in greater detail below.

(2) FIG. 1 shows a flow diagram of a method according to a first specific embodiment.

(3) FIG. 2 shows the dependency of the temporal resolution of a location determination on the velocity of an exemplary vehicle.

(4) FIG. 3 shows schematically, a telematics control unit according to a second specific embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(5) FIG. 1 illustrates the basic sequence of a method according to the present invention (10) across a single scanning cycle; the method steps will be described using the example of a position determination inside a vehicle. To begin with, the vehicle in this scenario measures its ego velocity (process 11) and increments a counter (process 12) as a function of the ego velocity. It then checks whether the counter has reached a predefined threshold value (decision 13). If this condition has been satisfied (branch Y), the vehicle carries out a position determination (process 14) and further processes it. The further processing may be carried out either in the memory medium or externally, by transmitting the data by way of a wire-conducted or wireless communications path (such as via an air interface). However, if the counter does not reach the mentioned threshold value, the vehicle will repeat the executed steps in due course, starting with another measurement (11).

(6) In order to achieve an acceptable compression, certain weight factors which are used as the basis for the desired scanning resolution are defined in a corresponding software. These weight factors are flexible and are able to be modified and configured at any time, also via the air interface.

(7) By way of example, the desired data resolution may be defined in the following manner:

(8) TABLE-US-00001 Velocity Typical Use Desired Range (km/h) Application Resolution (km) 0-50 Within city limits 0.2-1.sup.  50-100 Federal highway 1-6 100-250  Interstate  6-10

(9) In an effort to generalize the relation between the velocity and the desired resolution defined in this way, the resolution in km is plotted against the velocity in km/h, a curve is adapted on the basis of the tangens hyperbolicus, and the function graph according to FIG. 2 is obtained as a result.

(10) If the desired minimum resolution is denoted as a, the maximum resolution as b, and the driving velocity as v, then the following generalized relation may be derived for resolution R.sub.n given the selection of a suitable constant variable c:

(11) $R_n=\frac{1}{10}\left(\left(a+b\right)+\left(b-a\right)\tanh \frac{v-v_0}{c}\right)$

(12) Weight factor G.sub.n thus satisfies the following equation:

(13) $G_n=\frac{{\mathrm{Tv}}_n}{R_n}$

(14) In order to determine a velocity-dependent scanning rate, a certain weight factor is allocated to each value of the velocity. For each velocity v.sub.1 to v.sub.n that is polled per second, the corresponding weight factor G.sub.1 to G.sub.n is selected and used in order to increment a counter by the selected weight factor. As soon as the counter reaches a predefined threshold value T, the data are transmitted and the counter is reset to zero. In this case, the location is ascertained using GPS or some other global navigation-satellite system (GNSS) and transmitted.

(15) In such a case, threshold value T is selected so that the counter reaches it according to the described method (10) when—at the given velocity—a distance that corresponds to the desired spatial resolution has been covered, that is to say, after the following driving time:

(16) $t_n=\frac{R_n}{v_n}$

(17) The threshold value may thus be determined as the smallest common multiple of the values t.sub.1 to t.sub.25 according to the following lookup table (LUT):

(18) TABLE-US-00002 n v.sub.n R.sub.n t.sub.n G.sub.n 1 0-10 km/h 0.1000 km 72.00 s 1.00 2 10-20 km/h 0.3000 km 72.00 s 1.00 3 20-30 km/h 0.5000 km 72.00 s 1.00 4 30-40 km/h 0.7000 km 72.00 s 1.00 5 40-50 km/h 0.9000 km 72.00 s 1.00 6 50-60 km/h 1.3167 km 86.18 s 0.84 7 60-70 km/h 2.1167 km 117.23 s 0.61 8 70-80 km/h 2.9167 km 140.00 s 0.51 9 80-90 km/h 3.7167 km 157.41 s 0.46 10 90-100 km/h 4.5167 km 171.16 s 0.42 11 100-110 km/h 5.625 km 192.86 s 0.37 12 110-120 km/h 6.875 km 215.22 s 0.33 13 120-130 km/h 8.125 km 234.00 s 0.31 14 130-140 km/h 9.375 km 250.00 s 0.29 15 140-150 km/h 10.625 km 263.79 s 0.27 16 150-160 km/h 10.72 km 248.98 s 0.29 17 160-170 km/h 10.76 234.76 s 0.31 18 170-180 km/h 10.8 km 222.17 s 0.32 19 180-190 km/h 10.84 km 210.94 s 0.34 20 190-200 km/h 10.88 km 200.86 s 0.36 21 200-210 km/h 10.92 km 191.77 s 0.38 22 210-220 km/h 10.96 km 183.52 s 0.39 23 220-230 km/h 11.00 km 176.00 s 0.41 24 230-240 km/h 11.04 km 169.12 s 0.43 25 240-250 km/h 11.08 km 162.81 s 0.44

(19) Threshold value T is freely definable but may be in a correlation with the driving time, for instance as the smallest common multiple of the values t.sub.0 to t.sub.n.

(20) It is understood that the weight factor and the threshold value are able to be defined either using a predefined lookup table (LUT) or, in a deviating specific embodiment, they can also be defined using a direct calculation of the desired resolution, without departing from the scope of the present invention.

(21) In order to define a lookup table that is independent of the accuracy of the polling frequency—the above table is configured for an accuracy of is—the sequence is able to be modified in the following manner: To begin with, a lookup table for a high scanning rate of 1000 Hz, for example, is calculated. In this case, the difference Δt of the instantaneous time and the time of the last scanning would have to be utilized in each iteration. The counter is then incremented by the product of time difference Δt and the weight factor allocated to the instantaneous velocity.

(22) This method (10) may be implemented in software or hardware, for example, or in a mixed form of software and hardware, such as in a telematics control unit (20), as illustrated by the schematic representation of FIG. 3.