Device for correcting a spacing value and/or for correcting a relative speed value, vehicle, and method

Abstract

A device for increasing the precision of the distance and the relative velocity of a camera-based sensor with the aid of longitudinal acceleration for use in vehicles, e.g., in passive safety applications. In a first arithmetic unit of the inventive device, a correction of a slowly repeated camera-based measurement of the distance to an object is performed with the aid of an internal, longitudinal acceleration signal sampled at a much higher rate, wherein the inventive correction may be performed within an arithmetic unit of the camera, within a passive safety system or in a unit outside the camera and outside the safety system in the vehicle.

Claims

1. A device for correcting a distance value and/or for correcting a relative-velocity value for a vehicle, the device comprising: a first arithmetic processor of the vehicle configured to: correct a distance value of the vehicle relative to an object present in a surroundings of the vehicle and/or to correct a relative-velocity value v.sub.1 of the vehicle relative to the object: 1) by determining the corrected distance value and/or the corrected relative-velocity value v.sub.1 from camera images captured by a camera of the vehicle only when a time period during which the distance value and/or the relative-velocity value v.sub.1 are to be corrected is greater than or equal to a time period required to perform the correction by the camera images, and 2) by determining the corrected distance value and/or the corrected relative-velocity value v.sub.1 from a proper-acceleration value a of the vehicle measured by an acceleration sensor only when the time period during which the distance value and/or the relative-velocity value v.sub.1 are to be corrected is less than the period required to perform the correction by the camera images, and control a physical system of the vehicle based on the corrected distance value and/or the corrected relative-velocity value v.sub.1.

2. The device according to claim 1, wherein the first arithmetic processor is designed to calculate a velocity value v.sub.2 in the form of a time integral from t=0 to t.sub.1 of the measured proper-acceleration value a, according to the formula: ${}_0^{t1}a\mathrm{dt}.$

3. The device according to claim 2, wherein the first arithmetic processor is designed to generate a corrected distance value and/or to generate a corrected relative-velocity value v.sub.3, wherein v.sub.3=v.sub.1v.sub.2 for the corrected relative-velocity value v.sub.3 generated by the first arithmetic processor if the measured proper-acceleration value a is negative and thus represents a deceleration, and wherein v.sub.3=v.sub.1+v.sub.2 for the corrected relative-velocity value v.sub.3 generated by the first arithmetic processor if the measured proper-acceleration value a is positive.

4. The device according to claim 1, further comprising: a storage unit, wherein a threshold value a.sub.SW of the proper acceleration of the vehicle is stored in the storage unit, and wherein the first arithmetic processor is designed to compare the measured proper-acceleration value a with the threshold value a.sub.SW stored in the vehicle and to correct the distance value and/or the relative-velocity value v.sub.1 only if an amount of the measured proper acceleration a is greater than an amount of the stored threshold value a.sub.SW.

5. The device according to claim 1, wherein the acceleration sensor is a longitudinal-acceleration sensor adapted to measure a longitudinal-acceleration value a of the vehicle.

6. A vehicle having a device for correcting a distance value and/or for correcting a relative-velocity value for the vehicle according to claim 1.

7. The vehicle according to claim 6, said vehicle further comprising: a passive safety system, wherein the passive safety system is designed to actuate at least one component selected from the group consisting of a seat belt tensioner, an airbag, a pedestrian airbag, a restraint system, a passive restraint means, and an active hood, and wherein the passive safety system is designed to use the distance value corrected by the first arithmetic processor and/or the relative-velocity value corrected by the first arithmetic processor to actuate one of the components.

8. A method for correcting a distance value and/or a relative-velocity value of a vehicle, said method comprising: providing, by an arithmetic processor of the vehicle, a distance value of the vehicle relative to an object present in a surroundings of the vehicle and/or a relative-velocity value v.sub.1 of the vehicle relative to said object, said distance value and said relative-velocity value v.sub.1 being determined on the basis of images from a camera, providing, by the arithmetic processor of the vehicle, a proper-acceleration value a of the vehicle measured by an acceleration sensor, and performing, by the arithmetic processor of the vehicle, a correction of the distance value and/or performing a correction of the relative-velocity value v.sub.1 relative to the object: 1) by determining the corrected distance value and/or the corrected relative-velocity value v.sub.1 from the images captured by the camera of the vehicle only when a time period during which the distance value and/or the relative-velocity value v.sub.1 are to be corrected is greater than or equal to a time period required to perform the correction by the camera images, and 2) by determining the corrected distance value and/or the corrected relative-velocity value v.sub.1 from a proper-acceleration value of the vehicle measured by the acceleration sensor only when the time period during which the distance value and/or the relative-velocity value v.sub.1 are to be corrected is less than the period required to perform the correction by the camera images, and controlling a physical system of the vehicle based on the corrected distance value and/or the corrected relative-velocity value v.sub.1.

9. The method according to claim 8, said method further comprising: calculating a velocity of an impact of the vehicle on the object at a corresponding moment of impact, and wherein the corrected distance value and/or the corrected relative-velocity value are/is used to calculate impact velocity and the moment of impact.

10. The method according to claim 8, said method further comprising: using the corrected distance value and/or the corrected relative-velocity value to actuate a component of the vehicle selected from the group consisting of a seat belt tensioner, an airbag, a restraint system, a passive restraint means, and an active hood.

11. The device according to claim 3, wherein time t.sub.1 is selected such that t.sub.1 is smaller than a delay time required by the determination of the distance value and/or of the relative-velocity value v.sub.1 by the camera images.

12. The method according to claim 9, said method further comprising: using the corrected distance value and/or the corrected relative-velocity value to actuate a component of the vehicle selected from the group consisting of a seat belt tensioner, an airbag, a restraint system, a passive restraint means, and an active hood.

13. The device according to claim 2, wherein time t.sub.1 is selected such that t.sub.1 is smaller than a delay time required for the determination of the distance value and/or of the relative-velocity value v.sub.1 by the camera images.

14. The device according to claim 2, further comprising: a camera, and a second arithmetic processor, wherein the camera is designed to generate images of the surroundings of the vehicle, wherein the second arithmetic processor is designed to determine the distance value of the vehicle relative to the object and/or the relative-velocity value v.sub.1 of the vehicle relative to the object on the basis of the generated images of the camera, and wherein a time t.sub.2 is required for image generation by the camera and for the determination of the distance value and/or of the relative-velocity value by the second arithmetic processor, and wherein t.sub.1 is selected such that t.sub.1 is smaller than t.sub.2.

15. The device according to claim 3, further comprising: a second arithmetic processor, wherein the camera obtains images of the surroundings of the vehicle, wherein the second arithmetic processor is designed to determine the distance value of the vehicle relative to the object and/or the relative-velocity value v.sub.1 of the vehicle relative to the object on the basis of the generated images of the camera, and wherein a time t.sub.2 is required for obtaining images by the camera and for the determination of the distance value and/or of the relative-velocity value by the second arithmetic processor, and wherein t.sub.1 is selected such that t.sub.1 is smaller than t.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a vehicle having a device for correcting a distance value and/or for correcting a relative-velocity value according to an exemplary embodiment of the invention.

(2) FIG. 2 shows a vehicle having a device for inventive correction according to an exemplary embodiment of the invention.

(3) FIG. 3 shows a flow chart of a method according to an exemplary embodiment of the invention.

(4) The figures are shown schematically and not true to scale. When the same or similar reference numerals are used in different figures in the following description, they denote the same or similar elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) FIG. 1 shows a vehicle 101 having a device 100 for correcting a distance value and/or for correcting a relative-velocity value for the vehicle 101. The device 100 has a first arithmetic unit 102. An acceleration sensor 103 measuring proper-acceleration values a of the vehicle is also present in the vehicle 101, said acceleration sensor 103 performing said measurements in a continuous or clocked manner. The vehicle 101 also has a camera 104 generating images of the surroundings of the vehicle. The second arithmetic unit 105 is arranged within the camera 104. The second arithmetic unit is designed to determine the (within the meaning of the invention) uncorrected distance value of the vehicle relative to an object and/or the uncorrected relative-velocity value v.sub.1 of the vehicle relative to the object on the basis of the generated images of the camera. This distance value and/or relative-velocity value of the vehicle determined by camera images is transmitted to the device 100. The first arithmetic unit 102 of the device 100 is designed to correct the distance value and/or relative-velocity value transmitted by the second arithmetic unit. In particular, the arithmetic unit 102 is designed to perform this correction depending on a proper-acceleration value a of the vehicle 101 measured by the acceleration sensor 103. The inventive correction of relative velocity can realize safety-relevant advantages for the user of the vehicle 101 particularly in time periods between a first determination of relative velocity and a second determination of relative velocity in the second arithmetic unit 105. In particular, the device 100 may transmit the corrected value/s to a passive safety system 106 of the vehicle. The passive safety system 106 can actuate the component 107 on the basis of the corrected values of the distance and/or of the relative velocity of the vehicle. The component 107 may be designed, e.g., as a seat belt tensioner, an airbag, a restraint system, a pedestrian airbag, a passive restraint means, and an active hood. The passive safety system 106 is designed to use the corrected values or the corrected value to actuate one of the components, i.e., the corrected values determined by the first arithmetic unit are directly used for an actuating decision.

(6) By means of the device 100, an increase in the precision of the distance and/or the relative velocity of a camera-based sensor with the aid of longitudinal acceleration for use in passive safety systems is provided, wherein the acceleration sensor 103 may be designed, e.g., as a longitudinal-acceleration sensor whose data are used, for a short time, to correct the data of the sluggish camera-based detection system, wherein correction may be performed for a time period in which a too sluggish reaction of the determination by the camera 104 with the second arithmetic unit 105 is to be expected. This time period may depend on the technical realization of the camera system and may have different lengths. With the aid of the acceleration signal of the acceleration sensor 103, which can be sampled at a higher rate, a further corrected distance value and/or relative-velocity value is generated by the first arithmetic unit 102 that may then be used instead of the raw data of the slow, camera-based system in the passive safety system 106, e.g., to predict accident severity, the moment of impact, and impact velocity. For example, the device 100 may use the motion equation to anticipate the future motion of the vehicle that can be estimated by means of the currently measured acceleration of the vehicle.

(7) According to a further exemplary embodiment of the invention, FIG. 2 shows a vehicle 201 having an inventive device 200, in which the first arithmetic unit 202 is arranged. The vehicle 201 also has a camera 204 generating images for determining the distance value and/or the relative-velocity value of the vehicle. These values are determined in the separately arranged second arithmetic unit 205. The vehicle 201 also has a longitudinal-acceleration sensor 203 measuring the longitudinal acceleration of the vehicle 201, wherein relative velocity is symbolically indicated by arrow 207 in FIG. 2. Furthermore, a second vehicle 208 is symbolically shown as an object present in the surroundings of the vehicle 201. Furthermore, a system 206, to which the device 200 transmits the corrected values, is shown. For example, this system 206 is designed as a passive safety system, but other exemplary embodiments of the system 206 are also possible. In the vehicle 201, the camera 204 generates an image of a surroundings of the vehicle. In the second arithmetic unit 205, the distance value of the vehicle relative to the second vehicle 208 and, on the basis thereof, the relative velocity v.sub.1 207 of the vehicle relative to the second vehicle 208 are determined. The longitudinal-acceleration sensor 203 has measured the proper acceleration a of the vehicle and transmitted this value to the first arithmetic unit 202. This first arithmetic unit corrects the previously determined distance value and/or the previously determined relative-velocity value by means of the proper acceleration of the vehicle measured by the acceleration sensor, whereby a corrected distance value and/or a corrected relative-velocity value are/is generated by the first arithmetic unit 202, wherein the first arithmetic unit calculates a velocity value v.sub.2 in the form of a time integral from t=0 to t.sub.1 of the measured proper-acceleration value a. Subsequently, these generated values may be used for further purposes, particularly for the actuating decision of components of the passive safety system. In this manner, an essentially improved prediction of impact velocity and of the moment of impact to be expected is achieved at least for accidents with stationary or non-accelerated targets. In particular, such a prediction of impact velocity and a prediction of the moment of impact to be expected can be calculated on the basis of the corrected values in the vehicle, which may be performed, e.g., in the first arithmetic unit 202.

(8) According to a further exemplary embodiment of the invention, FIG. 3 shows a flow chart of a method for correcting a distance value and/or a relative-velocity value of a vehicle. In step S1, a distance value of the vehicle relative to an object present in a surroundings of the vehicle and/or a relative-velocity value v.sub.1 of the vehicle relative to said object are/is provided, said distance value and said relative-velocity value v.sub.1 being determined on the basis of camera images. A proper-acceleration value a of the vehicle measured by an acceleration sensor is also provided (in step S2 of FIG. 3). In step S3, a correction of the previously provided distance value and/or a correction of the previously provided relative-velocity value v.sub.1 are/is performed, wherein the correction of the distance value/of the relative-velocity value v.sub.1 is performed depending on the proper-acceleration value a of the vehicle.

(9) Thus, this method uses the motion equation to anticipate the future motion of the vehicle that can be estimated by means of the currently measured acceleration of the vehicle.

(10) According to a further exemplary embodiment, the method according to FIG. 3 includes the additional step of calculating a velocity of the impact of the vehicle on the object at a corresponding moment of impact. The corrected distance value and/or the corrected relative-velocity value are/is used to calculate impact velocity and the moment of impact.

(11) In a further specified exemplary embodiment, the additional step of using the corrected distance value and/or the corrected relative-velocity value to actuate a component of the vehicle is added to the method according to FIG. 3 or to the previously mentioned method. This component may be, e.g., a seat belt tensioner, an airbag, a restraint system, a passive restraint means, a pedestrian airbag, and/or an active hood.

(12) According to a further exemplary embodiment, the method includes the additional step of estimating a distance of the vehicle to the object on the basis of at least two camera images. Furthermore, the step of calculating the relative velocity of the vehicle relative to the object by dividing the estimated distance by a time difference between the corresponding camera images is included.

(13) In addition, it should be noted that comprising does not exclude any other elements or steps and a does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. Reference numerals in the claims are not to be considered as being restrictive.