WO2017005688A1

WO2017005688A1 - Method for evaluating a received signal of an ultrasonic sensor

Info

Publication number: WO2017005688A1
Application number: PCT/EP2016/065698
Authority: WO
Inventors: Michael Hallek; Thomas Jung; Prasad Haridas; Thomas Neumann
Original assignee: Valeo Schalter Und Sensoren Gmbh
Priority date: 2015-07-07
Filing date: 2016-07-04
Publication date: 2017-01-12
Also published as: DE102015110960A1

Abstract

The invention relates to a method for evaluating a received signal (9) of an ultrasonic sensor of a motor vehicle (1), in which method the ultrasonic sensor is excited to send an ultrasonic signal by means of a transmitted signal, the received signal (9) is determined on the basis of the ultrasonic signal reflected by an object (8) in the surrounding area (7) of the vehicle (1), a correlation signal (10) is determined from a correlation of the transmitted signal with the received signal (9), and the received signal (9) is assessed on the basis on an amplitude (A_E) of the received signal (9) and an amplitude (A_K) of the correlation signal (10), wherein a ratio of the amplitude (A_E) of the received signal (9) and the amplitude (A_K) of the correlation signal (10) is determined, and the received signal (9) is assessed on the basis of the determined ratio.

Description

METHOD FOR EVALUATING A RECEIVE SIGNAL ONE

ULTRASOUND SENSORS

The present invention relates to a method for evaluating a received signal of an ultrasonic sensor of a motor vehicle, in which the ultrasonic sensor for emitting an ultrasonic signal is excited by a transmission signal, based on the reflected from an object in the vicinity of the motor vehicle ultrasonic signal, the received signal is determined, a correlation signal from a Correlation of the transmission signal is determined with the received signal and based on an amplitude of the received signal and an amplitude of the correlation signal, the received signal is evaluated. In addition, the present invention relates to an ultrasonic sensor device for a motor vehicle. Furthermore, the present invention relates to a driver assistance system with such an ultrasonic sensor device. Finally, the present invention relates to a motor vehicle with such a driver assistance system.

The interest is directed in the present case in particular to ultrasonic sensors for

Motor vehicles. Such ultrasonic sensors are used, for example, to detect objects in an environment of the motor vehicle. Furthermore, the distance to an object can be determined with the ultrasonic sensors. The

Ultrasonic sensors usually comprise a membrane, which is excited to emit an ultrasonic signal with a corresponding transducer to mechanical vibrations. For this purpose, the transducer is excited by means of a corresponding transmission signal, for example an electrical voltage. The ultrasound signal emitted by the ultrasound sensor is reflected by the object and strikes the membrane of the ultrasound sensor again. As a result of the incoming ultrasonic signal, the membrane is excited to mechanical vibrations. This mechanical

Vibrations can be detected with the transducer and in the form of a

Receiving signal, such as an electrical voltage can be provided. On the basis of the received signal, the transit time between the transmission of the

Ultrasonic signal and the arrival of the reflected ultrasonic signal and from this the distance between the motor vehicle and the object are determined.

Ultrasonic sensors are used, for example, in driver assistance systems, such as

Parking assistance systems, used. In today's parking aid systems more and more functionalities are used, which stand out from the classic parking operation. In addition to the cross-functional use of ultrasonic sensors, such as For example, for automatic braking, the classification of objects in the environment plays an increasingly important role. Above all, it is more crucial

Significance that with increasing number of functions also the activation times of the ultrasonic sensors are extended. The ultrasonic sensors are activated at low vehicle speeds and continuously perform measurements. This leads to an increased mutual influence of the systems.

For this purpose, it is known from the prior art that modern ultrasound systems encode their emitted ultrasound signals accordingly in order to distinguish their own emitted ultrasound signal from others. This describes the

DE 10 2010 033 384 A1 discloses a method for evaluating an echo signal for

Vehicle environment detection, which preferably operates in the ultrasonic frequency range. In this case, a measurement signal is emitted with a predefinable coding and received a resulting encoded echo signal with Nutzsignalanteilen and / or interference signals and evaluated. In order to distinguish the different signal components and to recognize the useful signal components, the received echo signal is evaluated according to a correlation with the transmitted measuring signal. In this case, a signal component of the received echo signal can be classified as relevant if the weighted amplitude and the weighted correlation of the signal components of the received echo signal each reach or exceed a predetermined predetermined threshold value.

It is an object of the present invention to provide a solution, such as

Receiving signals of an ultrasonic sensor of a motor vehicle can be evaluated easier and more reliable.

This object is achieved by a method by a

Ultrasonic sensor device, by a driver assistance system and by a

Motor vehicle with the features according to the respective independent claims. Advantageous embodiments are the subject of the dependent claims, the description and the figures.

An inventive method is used to evaluate or rate a received signal of an ultrasonic sensor of a motor vehicle. In this case, the ultrasonic sensor is excited to emit an ultrasonic signal with a transmission signal. In addition, based on the object in the environment of the

Motor vehicle reflected ultrasonic signal determines the received signal. Furthermore, will determines a correlation signal from a correlation of the transmission signal with the reception signal. In addition, based on an amplitude of the received signal and an amplitude of the correlation signal, the received signal is evaluated. In addition, it is provided that a ratio of the amplitude of the received signal and the amplitude of the correlation signal is determined and the received signal is evaluated on the basis of the determined ratio.

The inventive method relates to an ultrasonic sensor for a motor vehicle. The ultrasound sensor can be part of a driver assistance system, for example, with which objects in the surroundings of the motor vehicle can be detected. For detecting the object, an ultrasonic signal is transmitted with the ultrasonic sensor. For this purpose, a membrane of the ultrasonic sensor with a corresponding transducer, such as a piezoelectric element, are excited to mechanical vibrations. In this case, the transducer element with a transmission signal, in particular a time-varying voltage can be applied. The ultrasonic signal reflected by the object in the vicinity of the motor vehicle again strikes the membrane, whereby mechanical vibrations are generated. This mechanical

Vibrations of the membrane can be detected with the transducer element and output in the form of the received signal, in particular a time-varying electrical voltage. The transit time between the emission of the ultrasound signal and the reception of the reflected ultrasound signal and, therefrom, the distance between the motor vehicle and the object can then be determined on the basis of the transmission signal.

In the present case, it should now be determined whether the received signal originates from a real object in the surroundings of the motor vehicle or is based on a fault or an interference signal. In particular, it should be evaluated whether the received signal describes a real echo of the ultrasonic signal or a so-called apparent echo or ghost echo. For the evaluation of the received signal, on the one hand, the amplitude of the received signal is determined. Furthermore, the transmission signal with the

Received signal correlates and determines an amplitude of the correlation signal. The correlation signal thus describes the similarity or the correspondence between the transmission signal, which characterizes the emitted ultrasonic signal, and the reception signal, which characterizes the received echo of the ultrasonic signal. If the correlation signal has a relatively high amplitude, it can be assumed that the received signal from the

Transmission signal comes. Based on the amplitude of the received signal can be estimated whether the received signal describes a real echo of the ultrasonic signal or whether it originates from an interfering signal. By evaluating the ratio of

Amplitude of the received signal and the amplitude of the correlation signal, the received signal can be easily and reliably evaluated.

Preferably, the correlation signal is determined by means of a normalized correlation function. The correlation signal is determined from a predetermined, normalized correlation of the transmission signal with the reception signal. In this case, the correlation or the correlation function can be normalized such that at a

full match of the transmit signal with the receive signal, the amplitude of the correlation signal has a predetermined value. This predetermined value may correspond to the amplitude of the transmission signal or the amplitude of the reception signal. Thus, a predetermined value is given for the amplitude of the correlation signal with the case that the transmission signal completely coincides with the reception signal. In the real measurement, the received signal will not completely match the transmission signal. This is due to the air damping and / or the

Reflecting properties of the object justified. Nevertheless, the transmission signal and the reception signal have a relatively high similarity to each other. This results in a value for the amplitude of the correlation signal that is in the range of

predetermined value. This allows the received signal to be simple and

reliable way to be evaluated.

In one embodiment, the received signal is evaluated as a useful signal if the amplitude of the received signal and the amplitude of the correlation signal in

Are essentially the same. In other words, if the ratio of the amplitude of the received signal and the amplitude of the correlation signal has substantially the value one, the received signal is evaluated as a useful signal. As a useful signal, the received signal can be evaluated in particular when the received signal describes the real echo of the ultrasonic signal. Thus, it can be determined in a simple and reliable manner whether the received signal describes a real echo or a false echo.

According to a further embodiment, a distance between the motor vehicle and the object is determined based on the received signal, if the received signal is evaluated as a useful signal. The determination of the amplitude of the received signal and the amplitude of the correlation signal can be carried out with an evaluation device of the

Ultrasonic sensor itself or an ultrasonic sensor device, which the ultrasonic sensor and the evaluation comprises.

Likewise, the evaluation or evaluation of the received signal can be carried out with this evaluation device. The evaluation device can be formed for example by a corresponding electronics, a signal processor, a microprocessor or the like. Furthermore, it can be provided that the determination of the distance between the motor vehicle and the object is carried out with a control device or an electronic control device of the motor vehicle. The evaluation device can then transmit the received signal together with information which describes whether the received signal is a useful signal or an interfering signal to the control device. If that

Received signal is evaluated as a useful signal, the received signal from the

Control device to be evaluated directly.

In a further embodiment, the received signal is evaluated as an interference signal if the amplitude of the correlation signal is smaller than the amplitude of the received signal. If the amplitude of the received signal is significantly larger than the amplitude of the

Correlation signal, it can be assumed that the received signal is an interference signal or noise components comprises. These interference signals can originate, for example, from the signals from other ultrasonic sensors. Furthermore, such interference signals, for example, from compressed air sources, for example

Compressed air sources of trucks, which can also produce signals in the ultrasonic range come. Furthermore, the interference signal components can originate, for example, from monitoring systems for parking space recognition or for counting vehicles in road traffic, which are arranged, for example, in or at traffic lights. If the received signal is based on an interfering signal, it has a low agreement with the transmitting signal, resulting in a small amplitude of the correlation signal. Based on the comparison of the amplitude of the correlation signal and the

Amplitude of the received signal, this can be easily detected.

Preferably, it is provided that the received signal is filtered, if the

Received signal is evaluated as an interference signal. Again, as already explained, the evaluation of the received signal can take place with an evaluation device of the ultrasound sensor or of the ultrasound sensor device itself. In this case, the received signal can be transmitted to the control device together with the information that the received signal is an interference signal. By means of the control device, the received signal can then be correspondingly filtered in order to filter out the interference signal components from the received signal. Thus, that can Receive signal are filtered only if it has been judged that this interference signal comprises shares. It can also be provided that the control device evaluates the received signal accordingly in order to classify the interference signal components.

Furthermore, it is advantageous if the transmission signal is output with a predetermined coding. If, for example, a plurality of ultrasonic sensors is arranged on the motor vehicle, each of the ultrasonic sensors can be equipped with a

predetermined transmission signal to be excited. For coding, the transmission signal can be provided in the manner of a bit sequence. Thus, it can additionally be checked whether receive signals are based on the transmitted transmission signal.

An inventive ultrasonic sensor device for a motor vehicle is for

Performing a method according to the invention designed. The

Ultrasonic sensor device may comprise the ultrasonic sensor and the evaluation device. These can be arranged in a common housing as an example.

An inventive driver assistance system for a motor vehicle comprises an ultrasonic sensor device according to the invention. In addition, the driver assistance system may include, for example, a control device, which is formed by an electronic control unit (ECU - Electronic Control Unit) of the motor vehicle. The control device can be connected to the ultrasonic sensor device for data transmission. Furthermore, it can be provided that the driver assistance system has a plurality of

Ultrasonic sensor devices comprises.

A motor vehicle according to the invention comprises an inventive

Driver assistance system. The motor vehicle is designed in particular as a passenger car.

The preferred embodiments presented with reference to the process according to the invention

Embodiments and their advantages apply correspondingly to the ultrasonic sensor device according to the invention, the driver assistance system according to the invention and the motor vehicle according to the invention.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description, as well as those mentioned below in the description of the figures and / or features and feature combinations shown alone in the figures are not only in the combination given, but also in others

Combinations or alone, without departing from the scope of the invention. Thus, embodiments of the invention are to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained. Embodiments and combinations of features are also to be regarded as disclosed, which thus do not have all the features of an originally formulated independent claim.

The invention will now be described with reference to preferred embodiments and with reference to the accompanying drawings.

Showing:

1 shows a motor vehicle according to an embodiment of the present invention

Invention, which a driver assistance system with

Ultrasonic sensor devices comprises;

Fig. 2 is a received signal of an ultrasonic sensor device and a

Correlation signal describing the correlation of a transmission signal with the reception signal according to a first embodiment; and

Fig. 3, the received signal and the correlation signal according to another

Embodiment.

In the figures, the same and functionally identical elements are the same

Provided with reference numerals.

Fig. 1 shows a motor vehicle 1 according to an embodiment of the present invention, a plan view. The motor vehicle 1 is in the present case as

Passenger cars trained. The motor vehicle 1 comprises a

Driver assistance system 2. The driver assistance system 2 in turn comprises a

Control device 3, which may be formed for example by an electronic control unit (ECU - Electronic Control Unit) of the motor vehicle 1. In addition, the driver assistance system 2 comprises at least one ultrasound sensor device 4. In the present case, the driver assistance system 2 comprises eight ultrasound sensor devices 4. Four ultrasound sensor devices 4 are located in a front region 5 of the

Motor vehicle 1 and four ultrasonic sensor devices 4 arranged in a rear portion 6 of the motor vehicle 1. The ultrasonic sensor devices 4 comprise an ultrasonic sensor, not shown here, with which an object 8 in an environment 7 of the motor vehicle 1 can be detected. The ultrasonic sensor devices 4 and the ultrasonic sensors are used in particular to determine a relative position between the object 8 and the motor vehicle 1. The

Ultrasound sensor devices 4 may, for example, in corresponding

Through holes are arranged in the bumpers of the motor vehicle 1. It can also be provided that the ultrasonic sensor devices 4 are arranged concealed under the bumpers.

The ultrasound sensors of the ultrasound sensor devices 4 usually comprise a membrane, which may for example be pot-shaped and may be formed from aluminum. This membrane can be excited with a corresponding transducer element, such as a piezoelectric element to mechanical vibrations. In this way, an ultrasound signal can be emitted with the respective ultrasound sensor device 4, which is then reflected by the object 8 and returned to the ultrasound sensor device or the membrane. By the reflected ultrasonic signal or the echo of the ultrasonic signal, the membrane is excited to mechanical vibrations. These mechanical vibrations can be detected with the transducer element and in the form of a

Receiving signal 9 are output.

The transducer element is acted upon or excited by a predetermined transmission signal, in particular a time-varying voltage.

The received signal 9, which is provided with the transducer element, should now be evaluated or evaluated accordingly. This is shown schematically in FIG. There, the received signal 9 or an envelope of the received signal 9 as a function of the time t is shown on the left side. The course of a correlation signal 10 as a function of time t is shown on the right-hand side. The correlation signal 10 is from the correlation of the transmission signal with the Received signal 9 determined. In this case, an amplitude A _{K of} the correlation signal 10 is normalized accordingly. In the present case, an amplitude A _{E of} the received signal 9 is compared with the amplitude A _{K of} the correlation signal 10. This can be done with the

Evaluation of the ultrasonic sensor device 4 are performed.

From the comparison it follows that both the amplitude A _{E of} the received signal 9 and the amplitude A _{K of} the correlation signal 10 have the value 1, 2. The ratio of the amplitude A _{E of} the received signal 9 and the amplitude A _{K of} the correlation signal 10 are approximately equal to one. In this case, it can be considered that the reception signal 9 originates from the transmission signal. This can be done by the

Evaluation device of the ultrasonic sensor device 4, the reception signal 9 are transmitted together with the information that it is the reception signal 9 is a useful signal or an echo signal.

In comparison, FIG. 3 shows the case in which the received signal 9 is an interference signal or a signal with interference components. Here, the amplitude A _{E of} the received signal 9 in comparison to the amplitude A _{K of} the

Correlation signal 10 a much higher amplitude. In this case, the correlation signal 10 has an amplitude A _K which reaches the value 2. Here it could be assumed that there is a match between the transmission signal and the reception signal 9. On the basis of the evaluation of the ratio of the amplitudes A _E and A _K can be determined that this is an interference signal

or a received signal 9 with Störsignalanteilen acts. This information can be transmitted from the evaluation device of the ultrasonic sensor device 4 to the

Control device 3 are transmitted. In this case, the received signal 9 can be filtered accordingly by means of the control device 3. Thus, in particular the received signals 9 can be classified or evaluated accordingly.

In particular, it can be determined whether the received signal 9 describes a real echo or a so-called apparent echo.

Claims

claims

1 . Method for evaluating a received signal (9) of an ultrasound sensor of a motor vehicle (1), in which the ultrasound sensor for emitting an ultrasound signal is excited with a transmission signal, based on the reflected from an object (8) in the environment (7) of the motor vehicle (1)

Ultrasound signal, the received signal (9) is determined, a correlation signal (10) from a correlation of the transmission signal with the received signal (9) is determined and based on an amplitude (A _E ) of the received signal (9) and an amplitude (A _K ) of the correlation signal ( 10) the received signal (9) is evaluated,

characterized in that

a ratio of the amplitude (A _E ) of the received signal (9) and the amplitude (A _K ) of the correlation signal (10) is determined and the received signal (9) is evaluated on the basis of the determined ratio.

2. The method according to claim 1,

characterized in that

the correlation signal (10) is determined by means of a normalized correlation function.

3. The method according to claim 1 or 2,

characterized in that

the received signal (9) is evaluated as a useful signal if the amplitude (A _E ) of the received signal (9) and the amplitude (A _K ) of the correlation signal (10) in

Are essentially the same.

4. The method according to claim 3,

characterized in that

a distance between the motor vehicle (1) and the object (8) is determined on the basis of the received signal (9) if the received signal (9) is evaluated as a useful signal.

5. Method according to one of the preceding claims,

characterized in that the received signal (9) is evaluated as an interference signal if the amplitude (A _K ) of the correlation signal (10) is smaller than the amplitude (A _E ) of the received signal (9).

Method according to claim 5,

characterized in that

the received signal (9) is filtered if the received signal (9) is evaluated as an interference signal.

Method according to one of the preceding claims,

characterized in that

the send signal is output with a predetermined coding.

Ultrasonic sensor device (4) for a motor vehicle (1), which is designed to carry out a method according to one of the preceding claims.

Driver assistance system (2) for a motor vehicle (1) with at least one

Ultrasonic sensor device (4) according to claim 8.

Motor vehicle (1) with a driver assistance system (2) according to claim 9.