GB2498840A

GB2498840A - Method and device for sensing at least one moving object in the environment of a vehicle

Info

Publication number: GB2498840A
Application number: GB1221931.7A
Authority: GB
Inventors: Marcus Schneider; Michael Schoenherr; Ulrich Klee
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-12-06
Filing date: 2012-12-05
Publication date: 2013-07-31
Anticipated expiration: 2032-12-05
Also published as: GB2498840B; DE102011087839A1; FR2983586A1; FR2983586B1; ITMI20122060A1

Abstract

A method is created for sensing at least one moving object (20) in the environment of a vehicle, wherein the acoustic signals (45) transmitted by means of at least one ultrasonic sensor (30) and reflected by the object are received and evaluated for the purpose of determining the position and/or the movement of the object (20). The ultrasonic sensor (30) is switched over, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive mode, in which it can emit and receive acoustic signals, to a receive-only mode, in which it cannot emit, but can receive, acoustic signals. Further, the noise signals (46) emitted by the moving object (20) and received by means of the switched over to the receive-only mode are evaluated for the purpose of determining the position and/or the movement of the moving object.

Description

Description Title

Method and device for sensing at least one moving object in the environment of a vehicle

Field of the invention

The present invention relates to a method for sensing at least one moving object in the environment of a vehicle, wherein the acoustic signals transmtted by means of at least one ultrasonic sensor and reflected by the object are received and evaluated for the purpose of determining the position and/or the movement of the object. The inve.ntion also relates to a corresponding device for sensing at least one moving object in the environment of a vehicle. Furthr, the invention relates to a method for monitoring a blind spot df a vehicle by means of a method according to the invention for sensing at least one moving object in the environment of a vehicle. Furthermore, the invention relates to a blind-spot monitoring system for monitoring a blind spot of a vehicle by means of a device according to the invention for sensing at least one moving object in the environment of a vehicle. Finally, the invention relates to a vehicle assistance system having a device accordig to the invention for Sensing at least one movlhg object in the environment of a vehicle and/or a blind-spot monitoring system according to the invention.

Prior art

There are already known systems such as, for example, side-view assist systems (SVA systems), parking pilot systems or blind-spot monitoring systems, which provide the driver with information about objects in the environment of a vehicle, in particular in the blind spot of the vehicle.

-Ultrasonic sensors, inter alla, can be used in such systems for the purpose of detecting the objects.

Such a system, in particular a side-view assist system, is known, for example, from the document cvo 2008/017542. This side-view assist system comprises at least one ultrasonic sensor for sensing a moving object in the environment of a vehicle, a control unit for determining the distahce and/or the relative speed of the object, with the ambient conditions relevant thereto being taken into account as a measurement valüé, and an output unit for triggering a signal, when required, on the basis of the determined measurement value. The same side-view assist system additionally comprises at least one further ultrasonic sensor, for determining the aforementioned ambient conditions simultaneously with the determinatibn of the distance or the relevant speed of the moving object by means of the other ultrasonic sensor.

In the case of the aforementioned systems, the objects in the environment of a vehicle are sensed by means of at least one ultrasonic sensor switched to Ttran t and * receive mode", on the basis of a pulse-echo method.

However, if there is excessive vehicle ambient noise, this method no longer works The reason for this is that the ultrasonic measuring systems known from the prior art are based on the fact that the sensed signals represent the echoes of the emitted sound pulses. If the noise, component is too high, then, at virtually any distances, "false

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objects are sensed, resulting in a defective warning behaviour This noise is increased greatly, for example, as the speed increases; or by the tyre noises in the case of a variety of road surface conditions, for example in the case of a wet road surface, such that the sensing of objects by means of thepulse_echo method no longer works. For this reason, in the case of the side-vie assist systems known from the prior art the side-view assist function for sensing objects by means of the pulse-echo method is limited, for example, to a vehicle speed of 140 km/h. Consequently, these side-view assist systems are deactivated in the case of a vehicle speed of, for example, 140 km/h.

Furthermore, the document DE -102 34 611 Al discloses a method for monitoring the environment of a vehicle, wherein ambient noises are used as an additional information source for analysis of the ambient situation of a vehicle. A blind-pot warning system described therein comprises a distance_sensing sensor, which can be, for example; an ultrasonic sensor, a radar sensor o, also, an infrared sensor. In addition, the system comprises a directional microphone, which substantially senses ambient noises in a defined segment of environment In addjtior-j to the detection of a vehicle present in the blind spot, ambient noises are picked up by means of the directional microphone in order to classify the detected object on the basis of the acodstic signal. In addition, the coustic signal can also be used to deduce the relative speed between the first veic1e and the detected vehicle. For this, it is stated that this i_s advantageous Particularly in respect of any measurement failures and measurement errors of the sensor according to the invention.

Further, the document DE 102009 003 257 Al discloses the practice of using ultrasonic sensors for sensing noise signals.

Disclosure of the invention

Provided according to the invention is a method for sensing at least one moving object in the environment of a vehicle, wherein the acoustic signals transmitted by means of at -least one ultrasonic sensor and reflected by the object are received and evaluated for the purpose of determining the position and/or the movement of the object. In this case, the ultrasonic sensor is switched over, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive mode, in which it can emit and receive acoustic signal-s, to a receive-only mode, in which it cannot emit, but can receive, acoustic signals. Further, the noise signals emitted by the moving object *and received by the ultrasonic sensor switched over 0 the receive-only mode are evaluated for the purpose of determining the position and/or the mbvement of the moving object.

Furthermore provided according to the invention is a device for snsing at least one moving object in the envil±cnraent * of a vehicle, which device is realized to receive the * acoustic signals transmitted by means of at least one ultrasonic sensor and reflected by the object, and to * -. evaluate them by means of a control device for the purpose * of determining the position and/or the movement of the -5-, object. Furthermore, the control device is realized to switch over the ultrasonic sensor, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive mode, *in which it can emit and receive acoustic signals, to a receive-only mode, in which it cannot emit, but can receive, acoustic signals. Further, the control device is realized to evaluate the noise ignals emitted by the moving object and received by means of the ultrasonic sensor switched over to the receive-only mode, for the purpose of determining the position and/or the movement of the moving object.

The dependent claims disclose preferred developments of the invention.

In the case of the method according to the invention, the respective ambient situation, in particular the existing ambient noise, is used as a basi to determine whether the ultrasonic sensor is to operate in a transmit and receive mode, on the basis of a pulse-echo method, or in a different mode, not based on a pulse-echo method, such as, for example, in a receive-only mode. The ultrasonic sensor switched over to the receive mode is used in this case such that it serves only as a receiver and does not itself emit any ultrasonic signals.

Travelling vehicles always also emit a noise signal in the ultrasonic range, in particular because of wind, engine and tyre noises. In some cases, this noise signal can become * so strong that it exceeds the actual useful signal. By * means of an ultrasonic sensor used only as a receiver, however, it is possible to.determine an object distance solely on the basis of such a noise signal, for example emitted by an approaching vehicle Object detection can thus be performed, despite the noise signal being greater than the useful signal.

In.the case of the method according to the invention, the vehicle ambient noise level is determined, in particular, by means of a noise estimation method, in particular based on a frequency analysis.

In other words, switchover of the ultrasonic sensor to the receive-only mode can be effected, on the one hand, from a defined speed of the vehicle or by means of a continuous noise estimation method. In fhis case, the ambient noise can be determined, for example, by means of a frequency analysis. -It is advantageous in this case that the optimum operating state of the ultrasonic sensors used is always selected for the functioning of the device according to the invention, in dependence on the existing ambient conditions. Further; in this case the noise signal caused by an object is inte.rpreted as a useful signal, in particular as a distance * -signal for sensing the object. The device according to the invention can therefore remain activated as much as ever -and can have a good functionality, even if the ambient noise signal exceeds the actual useful signal of the ultrasonic sensors and, in particular, even in the case of very high vehicle speeds, of over 140 km/h. Further, also ensured is a significant reduction in the functionality limitations of the device according to the invention that result from the existing road surface conditions. -In the case of a particularly advantageous exemplary embodiment of the invention, the threshold_value characteristic (threshold-value curve) of the ultrasonic sensor switched over to receive-only mode is parameterised in such a way that an assignment can be effected between a distance of the object; *in relation to the vehicle, and a vehicle ambient noise level.

In other words, the ultrasonic sensor switched over to receive-only mode is parameterised in such a way that unambiguous assignment of the object distance on the basis * of the ambient noise level is possible.

Further provided accordin to the invention is a method for monitoring a blind spot of a vehicle, wherein the sensing of at least one moving object in the blind spot of the vehicle is effected by means of a method according to the invelition for sensing at least one moving object in the environment of a vehicle.

Furthrmore provided according to the invention is a blind-spot monitoring system for monitoring a blind spot of a vehicle, which system comprises a device according to the invention used for sensing at leat one moving object in the blind spot of the vehicle.

It is advantageous, in the case of the blind-spot monitoring system according to the invention, that it can remain activated as much as ever and can reliably monitor the blind spot bf the vehicle, even if the noise signal exceeds the actual useful signal, in particular even if the vehicle is travelling at high speeds of, for example, over kin/h. If the arñbient noise level is high, the ultrasonic noise being emitted from vehicles passing the first vehicle is even greater. Therefore, by means of the blind-spot monitoring device according to the invention, object detection or object identification can be effected solely on the basis of the high ambient noise received by means of the ultrasonic ensors, for example by means of the yre noises, produced on a wet road surface, that are caused b' the passing vehicles.

Also provided according to the invention is a vehicle assistance system having a device according to the inveption and/or a blind-spot monitoring system according to the invention.

Brief description of the drawings

Exemplary embodiments of the invention are described in detail in the following with reference to the accompanying drawings. In the drawings: Figure 1 shows a device fcr sensing at leastone moving object in the environment of a vehicle, according to a first embodiment of the invention, and Figures 2a to 2c each show a parametrised threshold-value characteristic, as a function of time, for the ultrasonic sensor from Figure 1, switched over to a receive-only mode, wherein, in Fiures 2b and 2c, the instants at which a measurement signal -produced from a received noise.signal exceeds the threshold_value characteristic -9-in each case, and the ccrresonding threshold values are shown.

Embodiments of the invention Figure 1 shows a device 10 for sensing at least one moving object 20 in the environment o a vehicle (not represented), according to a first embodiment-of the invention: The device 15 realized to receive the acoustic signals 45 transmitted 40 by means of at least one ultrasonic sensor 30 and reflected by the object 20, and to evaluate them by means of a control device 50 for the purpose of deternining the Position and/or the movement of the object 20. Furthermore, the control device 50 is realized to switch over the ultrasonic sensor -30, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive mode to a receive-only mode. Further, the control device is realized-to evaluate the noise signals 46, emitted by the moving object 20 and received by means of the ultrasonic sensor 30 switched over to the receive-only mode, for the purpose of determining the distance d and/cr the movement of the moving object 20.

In particular, the control device 50 is further realized to parameterise -the threshold_value characte.ristic of the ultrasonic sensor 30, switched over to.the receive-only mode, in such a way that unambiguous assignment between the object distande d and the vehicle ambient noise level can be effected -A parameterised threshold_value characteristic SWK for the ultrasonic sensor from Figure 1, switched over to a -10 -receive-only mode, is represented in each of Figures 2a to 2c. In each of these figures, the course of the threshold value sw is shown as a function of time T. According to the invetjon an ultrasonic-sensor switched over to the receive-only mode is to be parameterised such that unambiguous assignment of the object distance on the basis of the noise level is possible. This is still possible if the characteristic SWK for determining the digital distance value is a continuously falling functioh, as represented in each of Figures 2a to 2c. The characteristic represents the threshold-value curve SWK that must be exceeded by an ultrasonic signal in order for there to be a dIgital signal associated with detection of an object.

Used in this case is such a pararneterisation in which "the louder" an object is, "the closer" its presence is considered to be. For this purpose, Figures 2b and 2c also show the instants Tl, T2 at which a measurement signal, produced from a received noise.signal, exceeds the threshold_value characteristic SWK in each case, and the corresponding threshold values swn, SWK2. In Figures 2b and 2c, RN1 and Rt'32 denote the respective noise level present in the environment of the vehicle. Further, dl and- d2 are the object distances, which correspond to the -measured instants Ti andT2.

The travel situaEion depicted in Figures 2a to 2c can be interpreted -such that Figure ?a Corresponds to a passing vehicle that is so far away that it is not detected. When *the vehicle has approached such that, as represented in Figure 2b it has produced a noise level RN1 in the vehicle environment, it is detected on the basis of a noise signal emitted by it, at a first instant Tl, at which the first -1_i -noise signal has exceeded the threshold-value characteristic swx, at a first threshold value SW1. The thus measured first instant Ti Is assigned to a first object distance dl.

If the vehicle approaches further, then, as represented in -Figure 2c, it produces in the vehicle environment a noise level RN2 that is greater than the noise level 1*11. The vehfcle is dtbcted on the basis of a second noise signal emittedby it, at a second instant T2, earlier than the firstinstant Ti; at which the second noise signal has exceeded the threshold-value characteristic SWK, at a second threshold value SW2 that is greater than the first threshold value SW1. The thus determined second instant T2 is assigned to a second, lesser object distance d2.

In addition to the preceding written disclosure, eSpress reference is made, supplementall to the representation in Fiures 1 and 2a to 2c.

Claims

<claim-text>Claims 1. A method for sensing at least one moving object in the environment of a vehicle, wherein the acoustic signals transmitted by means of at least one ultrasonic sensor and reflected by the object are received and evaluated for the purpose of determining the position and/or the movement of the object, characterized in that the ultrasonic senor is switched over, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive mode, in which it can emit and receive acoustic signals, to a receive-only mode, in which it cannot emit, but can receive, acoustic signals, and the noise signals emitted by the mcvin object ahd received by means of the ultrasonic sensor switched ove± to the receive-only node are evaThated for the purpose of determining the position and/or the movement of the moving object..</claim-text> <claim-text>2. The method according to Claim 1, characterized in that the vehicle, ambient noise level IS determined by means of a noise estimation method, in particular based on a frequency analysis.</claim-text> <claim-text>3. The method according to either of the preceding claims, characterized in that a threshold-value characteristic of the ultrasonic sensor switched over to.receive-only mode is parameterised in such a way that an assignment can be effected between a distance of the object, in relation to the vehicle, and a vehicle ambient noise level.</claim-text> <claim-text>4. The method.for monitoring a blind spot ofa vehicle, wherein the sensing of at least one moving object in the blind spot of the vehicle is effected by means of a method according to any one of the preceding claims.</claim-text> <claim-text>5. A device for sensing at least one moving object in the environment of a vehicle, which device is realized to receive the acoustic signals transmitted by means of at least one ultrasonic sensor and reflected by the object, and to evaluate them by means of a control device for the purpose of determining the position and/or the movement of the object, characterized in that the control device is further realized to switch over the ultrasonic sensor, in dependence on the speed of the vehicle and/or a determined vehicle ambient noise level, from a transmit and receive rhode, in which it can emit and receive acoustic signals, to a receive-only mode, in which it cannot emit, but can receive, acoustic signals, and to evaluate the noise signals, emitted by the moving object and received by means of the ultrasonic sensor switched over to the receive-only mode, for the purpose of determining the position and/or the movement of the moving object.</claim-text> <claim-text>6. The device according to Claim 5, characterized in that the control device is further realized to determine the vehicle ambient noise level by means of a noise estimation method, in particular based on a frequency analysis.</claim-text> <claim-text>7. The device according to either of Claims 5 or 6, characterized in that the control device is further realized to parameterise the threshold-value characteristic of the ultrasonic sensor, switched over to the receive-only mode, in such a way that assignment between a distance of the object, in relation to the vehicle, and the vehicle. ambient noise level can be effected.</claim-text> <claim-text>8. A blind-spot moliitoring system for monitoring a blind spot of a vehicle, which system comprises a device according to at least one of Claims 5 to 7, fpr sensing at least one moving object in the blind spot of the vehicle.</claim-text> <claim-text>9.. A vehicle assistance system having a devibe according to any one of Claims 5 to 7 and/or having a blind-spot monitoring system according to claim 8.</claim-text> <claim-text>10. A method for sensing at least one moving object in the environment of a vehicle as herein described with reference to the accompanying drawings.</claim-text> <claim-text>11. A device for sensing at least one moving obj.ect in the environment of a vehicle as herein described with reference to the accompanying drawings.</claim-text> <claim-text>12. A blind-spot monitoring system as herein described with reference to the accompanying drawings.</claim-text> <claim-text>13. A vehicle assistance system as herein described with reference to the accompanying drawings.</claim-text>