EP1941299A1

EP1941299A1 - Method for determining a variable

Info

Publication number: EP1941299A1
Application number: EP06792901A
Authority: EP
Inventors: Ruediger Jordan
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-10-14
Filing date: 2006-08-18
Publication date: 2008-07-09
Also published as: WO2007042339A1; DE102005049129A1

Abstract

In the inventive method for determining a variable associated with an object (4), wherein the object (4) has a plurality of points (2) which are suitable for reflecting measurement signals, the probability (6) of reflections occurring at these points (2) is taken into account for the purpose of evaluating at least one measurement signal.

Description

Method for determining a size

description

The invention relates to a method and a device for determining a size associated with an object, as well as a computer program and a computer program product.

State of the art

A radar sensor usually measures maxima of temporary reflections on objects. However, these reflections do not describe any fixed points on the object but wander and jump depending on the viewing angle. Even the smallest changes in the viewing angle are sufficient to obtain a different reflection behavior. For objects that are larger than the separability of the radar sensor, several

Reflexes are measured simultaneously. Currently, a clustering of reflections through a fixed window (e.g., 2m * 8m) and an averaging of readings is practiced. To determine a trailing edge of the object, the locally closest reflex is selected. This can lead to sham movements of the object when the reflex jumps on the object or another part of the object reflects it more strongly. A further problem is a passing on a vehicle, the reflex running on an outer edge of the object in the direction of the own vehicle. In the worst case, this apparent movement of the object can lead to a false triggering of a Predictive Safety System (PSS).

Based on this, a method having the features of claim 1, a device having the features of claim 7, a computer program having the features of claim 10 and a computer program product having the features of claim 11 are presented. Advantages of the invention

In the method according to the invention for determining at least one quantity or state variable associated with an object, wherein the object has a plurality of locations suitable for the reflection of measurement signals, the

Evaluation of at least one measurement signal, an occurrence probability for reflections at these locations taken into account.

The inventive device for determining at least one associated with an object size, wherein the object more for the reflection of a

Measuring signal has suitable locations. The device is designed to take account of an occurrence probability for reflections at these points in order to evaluate at least one measurement signal.

Advantageous embodiments emerge from the dependent claims.

The invention also relates to a computer program with program code means for carrying out all the steps of a method according to the invention when the computer program is executed on a computer or a corresponding computing unit, in particular a device in a device according to the invention.

The invention further relates to a computer program product with program code means which are stored on a computer-readable data carrier to perform all the steps of a method according to the invention, when the computer program is executed on a computer or a corresponding computing unit, in particular a device in a device according to the invention.

In the invention, a statistical approach that takes into account the probability of reflecting points or points on an extended object, for example a vehicle, is used. Incoming measurements are weighted differently, depending on the current probability of occurrence. This in turn depends on the size, in particular a relative location or a relative speed, which is related to the object. For this purpose, the Occurrence probability derived from a comprehensive reflection model of the object.

With the invention, a so-called. Radar-reflex modeling is possible. Via environmental measurements it is possible to determine a location and / or a speed of a

Determine surrounding environment of the device object. In this case, a signal is transmitted and reflected by a location of the object as at least one measurement signal and received by a sensor. The device can be arranged in a vehicle and serve to monitor objects in an environment of this vehicle.

From all the measurement signals that have arrived from the object, a fused measurement value can finally be formed that optimally describes the sought-after physical quantities of the object. In a subsequent tracking algorithm, the fused measurement value can be further processed.

By applying a statistical distribution of the probability of occurrence and thus of radar reflections on the object, a location or velocity determination and thus an estimate of the state of the object can be carried out more accurately and reliably. Apparent movements of the object, which are caused by reflex movements on the object and thus falsify a measurement result, can be minimized with the method. Furthermore, movements in the longitudinal and in the transverse direction relative to the device can be taken into account.

A separate treatment of any size or measurement dimension, such as distance,

Speed or lateral offset of the object may increase handling of the model.

When evaluating measurement signals, which are provided by sensors or radar sensors which can be separated by an angle, passages on vehicles thus occur in the vehicle

Means no apparent movements in the longitudinal or transverse direction, ie the estimated location of the object does not move along an outer edge of the object, but describes on average the center of a trailing edge of the object. - A -

The method can be used with predictive safety systems (PSS2) and adaptive cruise control (ACCplus) systems.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

drawing

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described below in detail with reference to the drawings.

FIG. 1 shows in a diagram a probability of occurrence used for a distance measurement.

FIG. 2 shows in a diagram a probability of occurrence used for a speed measurement.

Figure 3 shows an example of an evaluation of a turntable measurement in a schematic representation.

FIG. 4 shows a diagram of a vehicle expansion model.

FIG. 5 shows a diagram of a distribution of reflections.

FIG. 6 shows a diagram of a reflex point shift. embodiment

The figures are interrelated and cross-described, like reference numerals designate like components.

When measuring a correct distance to a trailing edge as a point 2 of an object 4, which is designed here as a vehicle, the occurrence probability 6 or probability distribution of radar reflections shown in the diagram in FIG. 1 is taken as the basis, this is along the ordinate 8 plotted on the abscissa 10 for the distance.

One reason for an asymmetry of the occurrence probability 6 is that the trailing edge of the object 4 is not always estimated correctly. It happens, for example, that when measured for the first time objects 4 not the trailing edge but the leading edge is measured. The probability that the real trailing edge is farther back, which corresponds to a smaller distance, is higher than that the real trailing edge is further forward, which corresponds to a greater distance.

For a measurement of a correct speed of the object 4, the probability of occurrence 12 of radar reflections shown in the diagram from FIG. 2 is taken as the basis, which is also plotted along the ordinate 8 over the abscissa 10 for the distance.

Here, one reason for an imbalance is that the trailing edge is not always estimated exactly as point 2 of the object 4, but that each point, and therefore each point 2 of the object 4, can provide a correct velocity measurement. Measurements of the speed of the trailing edge are i.d.R. more accurate than those from more forward points of the object 4, as more power is reflected from the trailing edge.

For measuring a transverse offset of the object 4, the center of the trailing edge is estimated in its transverse direction. However, it should be noted that an exact location of the reflex strongly depends on a viewing angle of the object 4. Detailed examinations of objects 14, in a vehicle shown schematically in FIG. 3, which are measured on a turntable in at least two spatial directions x, y 16, 18, have shown that a measured angle lies on average at the points 20, 22, 24 which have the smallest relative distance to a sensor. When viewed from the front, a center is measured as the location 20 of the vehicle. In big

View angle ranges are measured only as corners 22, 24 of the vehicle corners. In between there are flowing transitions.

In accordance with these findings, an expansion model 26 for vehicles in a first and second spatial direction x, y 28, 30 has been developed as shown in FIG. It consists of a rectangular body 32 with a circular curve 34. Since in road traffic usually the trailing edge is measured as a point 33 of an object 35 via the expansion model 26, it is sufficient to model this. The goal is to estimate the center 37 of the trailing edge as a function of a viewing angle φ 38 from a sensor 36. This results in an occurrence probability of a distribution of reflections 40 at different locations, which is dependent on the viewing angle φ 38 of the object 35 or of the vehicle.

As can be seen from FIG. 4, the most probable displacement .DELTA.dy 42 of the reflex 40 to the center 37 of the trailing edge can be determined as the location 33 of FIG

Calculate object 35.

Figure 5 shows three examples of reflections distributions 44, 46, 48 plotted along an ordinate 50 along an abscissa 52 for the view angle φ 38 (Figure 4).

One problem, however, is an estimate of relative view angles. 54 odφ 56 according to FIG. 4, since these quantities are not measured directly by the sensor 36 or radar sensor. However, they can be estimated via the relative movement in x- and y-direction, 28, 30, over a road course or on the basis of a current own course of the observing sensor 36. However, the larger the distance between the sensor 36 and the object 35, the more uncertain the estimate becomes. This must be taken into account insofar as the estimated shift of reflections 40 at smaller distances is less important. By probabilistic considerations one obtains the set of curves 58 for shifts of reflections 40 shown in the diagram in FIG. 6 (FIG. 4). Each of these curves is for different distances dy 60 in the y-direction 28 according to FIG. 4 in the direction of distances dx 62 in the x-direction 28 according to FIG

Ordinate 64 plotted over the most likely displacement Δdy 42 along the abscissa 66. For this purpose, both a plurality of viewing angles φ 38 as well as measured values for distances dx 62 and dy 60 are generally supplied by the sensor 36.

All measured values are weighted by the probability of occurrence, so that this describes the sought-after physical variable. To determine a transverse offset, measurement signals, which preferably also lie on the trailing edge, are physically most heavily weighted.

From the probability of occurrence, a fused pseudo-measured value is formed, which describes the currently most probable velocity of the object 35 and the most probable location for the center 37 of the trailing edge of the object 35. This pseudo-measured value can be determined by means of common tracking algorithms, e.g. via Kalman filter, further processed.

Claims

claims

Method for determining at least one quantity associated with an object (4, 14, 35), wherein the object (4, 14, 35) comprises a plurality of points (2, 20, 22, 24, 33) suitable for reflection of measuring signals in which for the evaluation of at least one measurement signal an occurrence probability (6, 12) for

Reflections at these points (2, 20, 22, 24, 33) is taken into account.

2. The method of claim 1, wherein a relative location of the object (4, 14, 35) is determined.

3. The method of claim 1 or 2, wherein a relative speed of the object (4, 14, 35) is determined.

4. The method according to any one of the preceding claims, wherein the at least one measurement signal according to the probability of occurrence (6, 12) is weighted.

5. The method according to any one of the preceding claims, wherein the size of the object to be determined (4, 14, 35) depending on the probability of occurrence (6, 12) is determined.

6. The method according to any one of the preceding claims, wherein from the at least one measurement signal, a fused measurement is formed.

7. Apparatus determining at least one quantity associated with an object (4, 14, 35), wherein the object (4, 14, 35) has a plurality of locations (2, 20, 22, 24, 33) suitable for reflection of a measuring signal , which is adapted to account for the evaluation of at least one measurement signal, a probability of occurrence of reflections at these locations (2, 20, 22, 24, 33).

8. Apparatus according to claim 7, comprising means for evaluating the at least one measurement signal.

9. Device according to claim 7 or 8, comprising a transmitter for emitting a signal and a sensor (36) for receiving at least one of the object (4, 14,

35) has reflected measuring signal.

A computer program comprising program code means for carrying out all the steps of a method according to any one of claims 1 to 6, when the computer program is executed on a computer or a corresponding arithmetic unit, in particular a device in a device according to one of claims 7 to 9.

A computer program product comprising program code means stored on a computer-readable medium for carrying out all the steps of a method according to any one of claims 1 to 6, when the computer program is stored on a computer or a corresponding computing unit, in particular a device in a device according to one of claims 7 to 9, is executed.