GB2510262A

GB2510262A - Environment sensor system which evaluates interfering sound sources

Info

Publication number: GB2510262A
Application number: GB1400605.0A
Authority: GB
Inventors: Christopher Brown; Michael Scherl; Florian Haug
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2013-01-15
Filing date: 2014-01-14
Publication date: 2014-07-30
Anticipated expiration: 2034-01-14
Also published as: GB201400605D0; DE102013200458A1; FR3001040B1; CN103926580B; FR3001040A1; GB2510262B; CN103926580A

Abstract

An environment sensor system 1, suitable for use in a vehicle as an anti-collision aid, comprises a first receiver array (Sx) having a first receiver and a second receiver. The receivers are preferably ultrasound transceivers. Furthermore, the system comprises a transmitter for generating acoustic echoes at environment objects (R) and an evaluating unit which is configured to evaluate a phase difference between a reception signal received with the first receiver and the second receiver. A first directional information item for an interfering sound source (Q) causing interfering sound present in the reception signal can thus be ascertained for the first receiver array. In the reception signal, sound components containing a corresponding first directional information item are evaluated and can be suppressed. The first and second receiver may be disposed at an acoustic distance from each other which is less than the quotient of a speed of sound to be expected under operating conditions, and of twice a working frequency of the receivers. The system may further comprise a second array (Sy) comprising two further receivers, the first and second arrays cooperating to identify interfering sound sources.

Description

Description Title

Environment sensor system

Prior art

The present invention relates to an environment sensor system. In particular, the present invention relates to an ultrasound-based environmenc sensor system with improved robustness of the evaluation to interfering sound sources.

Environment sensor systems are used in the prior art, in particular in the automotive industry, to obtain information about distances from environment objects. Most of these systems are based on the evaluation of echoes which are picked up by system-based receivers. To generate the echoes at environment objects, suitable signals are radiated by the system into the system environment. On the basis of the propagation time of the received echoes, it is possible to infer the distance of the corresponding environment object from the receiver. In this process, interfering sound sources in the environment of the system can prevent or complicate an echo recognition. In particular, pulse-like interfering noises and sources in the ultrasound range can be suppressed only with difficulty for ultrasound-based systems.

In the automotive sector, furthermore, ultrasound sensor systems are known which consist of two to six individual sensors and are each installed in the vehicle rear end and/or in the vehicle front end. The distance from the obstacles is determined from the propagation time of the signals, the horizontal direction in which the environment object is situated, by trilateration. If, however, interfering sound sources are present in the environment, all the receivers of the system detect signals which do not correlate with the transmissicn pulse. Typically, obstacles at many or even all distances are then detected. For example, road sweeping machines, building machinery, tyre rolling noises, very heavy footsteps, a rattling set of keys or ultrasound systems of other vehicles (for example in a car park) interfere wiTh the evaluation of received echoes. In other words, in such a case it is typically no longer possible to distinguish interference and actual obstacles.

Furthermore, sound-based array systems are known in the prior art, which can determine the angle to a sound source on the basis of a phase difference between a plurality of receivers. Such a system is shown in FR-28l7973-A1 or DE 10 2010 062 990 Al. In such systems, two independent receivers are arranged very close to one another and from the phase difference of an incident wave front between the two receivers a direction of incidence is inferred.

However, in such systems too, interfering sound sources can interfere with an echo recognition (or phase difference evaluation) such that the system is "blind".

Disclosure of the invention

The above-mentioned disadvantages are solved according to the invention by a system having the features according to Claim 1. Accordingly, an environment sensor system according to the invention has a first receiver array which can be embodied, for example as in DE 10 2010 062 990 Al, with a first receiver and a second receiver. A receiver in the context of the present invention is thus to be understood as "a unit which can convert an incident signal independently of other receivers", so that it is possible to ascertain, for example, a phase difference for one and the sane incident wave fron between two receivers arranged adjacent to one another, Of course, the receiver array can comprise a plurality of receivers, in particular arranged in different directions. In particular, the receiver array can conprise ultrasound transducers as first and second receiver. Additionally, the system can comprise a transmitter. The latter can be provided in the form of a dedicated component or realised by a transmission function also in the receivers of a receiver array. By means of the transmitter, the system according to the invention can be configured to emit a transmission signal, the echo(es) of which can, according to the invention and as explained below, be recognised and separately evaluated from arriving interfering sound. Furthermore, the system according to the invention comprises an evaluating unit which is configured to evaluate a phase (difference) between a reception signal received with the first receiver and the second receiver.

The evaluating unit can, for example, comprise a microcontroller, a microprocessor or another unit for signal evaluation which can additionally perform further system-internal or system-external functions. Furthermore, the evaluating unit is configured to ascertain a first directional information item for an interfering sound source for the first receiver array causing interfering sound present in the reception signal. In a one-dimensional receiver array, in which therefore at least two receivers are arranged horizontally beside one another, the first directional information item can thus ascertain a horizontal direction (or azimuth or horizontal angle) for an incident interfering sound wave front. An interfering sound signal can in this case be characterised and recognised by different properties. For example, in the context of a measuring cycle (i.e. for example of the time between a first and a second emission of a measuring signal into the environment) , an echo is to be expected only once from one and the same direcion, since other objects situated behind a reflecting environment object from the view of the receiver (array are acoustically shaded, i.e. cannot cast any echoes (apart from diffraction effects) Thus, as soon as a plurality of echoes or continuous sound is assigned to one and the same direction within a particular period of time predefined by the length of a measuring cycle, the presence of an interfering sound source can be inferred for This direction. Furthermore, the evaluating unit is configured to suppress (interfering) sound components present in the reception signal corresponding to the first directional information item. In other words, additional (useful) signals (such as e.g. echoes) which are present in the reception signal can likewise be resolved according to the direction and their evaluation enabled by not including sound components, corresponding solely to the first directional information item, in the evaluation (e.g. a propagation time or distance determination) . The directional resolution is in this case obtained, according to the invention, via the phase difference of the wave fronts arriving at the receiver array. This affords the advantage that, despite considerable interfering sound sources in the environment of the system, the system is "blind" solely to sound components corresponding to the directional information items of the interfering sound source, while sound components corresponding to other directional information items can be evaluated as known in the prior art by examining, for example, the signals (e.g. pulse wave fronts) with regard to their relative delay. In particular, a transmitter assigned to the system according to the invention can be used to radiate a signal into the environment of the system. In the evaluation of echoes received from the environment, on the one hand a delay between the emission of the signal and the reflected (useful) sound components can be detected and a distance travelled can be ascertained therefrom. On the other hand, a correlation between an emitted signal and a received reflected signal can also be carried out, in order to ascertain a relationship berween the two signals.

The dependent claims show preferred developments of the invention.

Preferably, the first and the second receiver of the receiver array according to the invention can have a distance from one another which is less than the guotient of a speed of sound to be expected under operating conditions and of twice a working frequency of the first receiver and of the second receiver. In the context of the present invention, "distance" is therefore to be understood with respect to the distance of the receivers from one another as an "acoustic" distance, thus, for example, the distance between respectiveiy corresponding sections of the receivers (membrane centre or the like) . As known, the speed of sound is dependent on different properties of the propagation medium, an outside air temperature of 50°C being mentioned as an exampie in the present case. The working freguency of customary ultrasound environment systems is in the range between approx. 35 kHz and 65 kHz, preferably between 45 kHz and 55 kHz, and is most preferably 48 kHz. The above arrangement ensures a suitable position-information or directional resolution of arriving ultrasound signals from the environment of the system.

More preferably, the first receiver array can comprise a third receiver, the third receiver defining with the first receiver and the second receiver a plane normal to the environment to be detected. In other words, the first and the second receiver can be spaced from one another in the horizontal direction, while the third receiver is arranged vertically to the first receiver and/cr to the second receiver. Furthermore, the evaluating unit can be configured to evaluate a phase difference between a reception signal received with the third receiver and the first receiver. In this way, it is also possible to evaluate a directional information item with regard to a vertical direction (or "height") for environment sound sources and echoes. Alternacively or additionally, the evaluation unit can be configured to evaluate a phase information item between a reception signal received with the third receiver and the second receiver. In this way, the system is configured by means of the evaluating unit to ascertain a second directional information item for an interfering sound source for the first receiver array causing interfering sound present in the reception signal.

In other words, an interfering sound source can be assigned by the above-defined arrangement not only with regard to a direction in the horizontal, but also with regard to a direction of incidence along a vertical, and taken into account in the evaluation of arriving sound components. For example, these sound components can be suppressed in order to be able to evaluate sound sources corresponding to other directional information items (for example (spherical) coordinates) . In this way, The range of the receiver array according to the invention in which the receiver array is temporarily blinded" by inerfering sound sources is reduced.

More preferably, the system according to the invention can further comprise a second receiver array with a fourth receiver and a fifth receiver. For the arrangement of the fourth receiver and the fifth receiver with respect to one another, the statements made in connection with the first and the second receiver can in this case apply analogously.

Furthermore, the evaluating unit can be configured to identify a direction from which interfering sound arrives at the first receiver array, on the basis of a first, and in particular also a second, directional information item ascertained by means of the first receiver array. If now a corresponding direction for the same interfering sound source is ascertained by means of the second receiver array, the evaluating unit can locate the interfering sound source exactly at the point of intersection of the two directions. In other words, with the aid of the second array it is not only possible to identify an interfering sound source with regard to its horizontal and vertical direction, but to determine an exact position from which received scund components in the recepticn signal are tc be suppressed. For the above-mentioned method, a certain distance of the two receiver arrays from one another is advantageous, since in this way an obtuse angle at the point of intersection of the two directions is favoured. In other words, a system configured as above is able to locate an interfering sound source according to its position and reliably recognise all environment objects at a certain distance from the interfering sound source, since at least at one of the two arrays the interfering sound source arrives from a different direction than the echoes of the real environment objects shaded or drowned out by it. Tn this way, a markedly smaller environment region is disturbed by an interfering sound source which influences a recognition of environment objects situated in the detection range of at least two arrays.

Of course, the evaluating unit can in this case further be configured to evaluate and locate also signals present remotely from the interfering sound source according to their position. In this way, a particularly good and interference-immune directional resolution can be carried out by means of the system according to the invention which is used.

It is helpful in this regard if the reception ranges of the first receiver array and of the second receiver array extensively overlap. In this way, it is possible to identify the interfering sound source from different directions as explained above and to ascertain the exact position (as described above) from the result.

More preferably, the receivers, in particular also the evaluating unit, are configured to be installed in a vehicle. For example, a first receiver array and a second receiver array can be arranged in a bumper of a vehicle at the vehicle front end and be connected to a common evaluating unit. In this case, it is advantageous if the receivers of the first receiver array and of the second receiver array communicate with the evaluating unit via separate channels. For example, these channels can be formed as individual lines. In principle, however, a coding of the information inside the receivers or inside the receiver arrays is, of course, also possible, with the result that lines can be saved and the information can be collected or can be led to The evaluating unit via a common channel.

More preferably, the system can be provided and configured for distance measurement, in particular to comprise means for outputting a signalling. These can, for example, generate an audio signal transmitter and/or a visual output and/or a haptically experienceable output. In this case, it is in particular advantageous to indicate such distances from environment objects and, using predefined threshold values, tc assess which predict a collision course fcr the vehicle. In this way, a fundamentally imminent collision can be reliably detected and averted.

More preferably, the system according to the invention can comprise one or more transmission units for emitting signals into the environmenc. For example, the receiver arrays themselves can be configured to transmit signals into the environment. In this way, it is particularly easily possible to relate the emitted signals to arriving echoes, avoiding additional outlay on hardware.

More preferably, the receivers can be ultrasound receivers, in particular ultrasound transceivers. In this way, the receiver arrays according to the invention are also formed as ultrasound-based receiver arrays, in particular ultrasound-based transceiver arrays.

According to a further aspect of the present invention, a vehicle comprising a system formed and configured as discussed above is proposed. In this case, the evaluating unit can, for example, perform further vehicle-specific functions, so that optionally computing power can be jointly used with other functions.

Brief description of the drawings

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings, in which: Figure 1 is a sketch illustrating the principle of the ultrasound-based recognition of an angle of incidence; Figure 2 is sketch illustrating the principle of a blinding of known ultrasound systems according

to the prior art;

Figure 3 is a system forned according to the invention, according to a first exemplary embodiment, Figure 4 is a flow diagram illustrating method steps of an exemplary embodiment acoording to the present invention; Figure 5 is a system formed acoording to the invention, according to a second exempiary embodiment; and Figure 6 shows a schematic illustration of an exempiary embodiment of a vehicle according to the invention having two systems according to an exemplary embodiment of a system according to the invention.

Embodiments of the invention Figure 1 shows an environment sensor system 1, comprising a receiver array S, which comprises a first receiver -1 and a second receiver 5x2. A wave front W from the environment of the system 1 is incident on the receivers Sxi and Sx2 of the receiver array S, at an angle. If a plane wave front W is assumed, there results a pach difference 6 between signal components arriving at the first receiver Si and at the second receiver 5x2. Since the speed of sound is known or can be determined from ascertainable quantities (for example using a temperature sensor) , It is possible Infer, from the distance between the receivers S->,2 together with the phase difference of the signals, the size of the angle a and hence a first directional information item for the interfering sound source, insofar as the signal/echo has been recognised e.g. by means of the above-described technique as interfering sound.

Figure 2 shows an environment sensor system 10 according to the prior art. A first reoeiver S1 and a seoond receiver S7 are arranged in a bumper 20 at a comparatively large distance from one another. An interfering sound source Q provides permanent interference of the receivers S< and S, so that environment objects in the respective reception ranges F and F7 remain unrecognised, that is to say the receivers S1 and S,j are "blind" to these objects.

Figure 3 shows a system 1 which is formed and configured according to the invention and in which a first receiver array S. and a second receiver array S are arranged in a bumper 20. An interfering sound source Q is arranged both in the reception range F,11 of the first receiver array S and in the reception range F7,yd of the second receiver array S and interferes with the reception of both receiver arrays S-,. Of two recognisable objects R, a first is arranged in an undisturbed region of the reception range E7+1, while a second object R is arranged both in the reception range E,+i and in the second reception range F7. This region is completely disturbed by the interfering sound source Q. However, the first receiver array S. can ascertain a first directional information item for the interfering sound source Q and the second receiver array S7 can identify a second directional information item for the interfering sound source Q. In this way, the object lying in both reception ranges E7,7+1 can nevertheless be recognised. An object U lying outside the second reception range F,711 but inside the first reception range E,+1 still remains unreoognised, sinoe a seoond directional information item from a second (other) viewing angle is not available to the system according to the invention.

Figure 4 shows a flow diagram, visualising method steps as can be carried out on the use of a system 1 according to the invention. The system srarts (Start") for example by switching on an ignition of a vehicle, engaging a reverse gear, actuating a corresponding actuating device or the like. In step 100 the environment is scanned, i.e. signals are received, by means of the first and second receiver array S, S. Tn step 200 it is ascertained whether a corresponding transmission signal has been transmitted. Tn other words, the reception signal is examined to establish whether it is a transmission signal of the system reflected by an environment object R. In step 300 a case differentiation takes place: if It is an echo (Y) , in step 400 an evaluation regarding the echo propagation time takes place. Optionally, a warning signal is output to a user when the distance falls below a predefined minimum distance. Subseguently, the method is continued with step 100, as described above. If in step 300 it is ascertained that the reception signal is interference (N) , in step 500 the reception signal is processed in a second manner. For example, this signal component in the reception signal is suppressed or is disregarded in the evaluation.

Subseguently, the method continues with the evaluation of step 100. At each instant between the steps, it is checked whether a predefined termination condition is fulfilled. If this is fulfilled, the method ends.

Figure 5 shows a system 1 according to the invention, which shows an evaluating unit 3 and a signalling device in the form of a loudspeaker 4 which is connected to the evaluating unit 3. Connected to the evaluating unit 3 is a two-dimensional receiver array S, consisting of receivers S>1 to S33. With the aid of this two-dimensional array, an exact direction for an interfering sound source emitting interfering sound can be ascertained. If two receiver arrays are used and they are situated at a minimum distance from one another, a point for the interfering sound source can be exactly determined by virtue of the ascertainable directional information items. In contrast to the arrangement illustrated in Figure 3, according to which only a "straight line" situated perpendicularly to the plane of the drawing can be determined for possible locations of the interfering sound source Q, it is possible by means of two receiver arrays at an evaluating unit 3 also to determine the last remaining coordinate for the interfering sound source and leave out interfering sound emitted by it in the evaluaion.

Figure 6 shows a passenger car 5 as the vehicle, which has both at its front end and a its rear end a bumper 20 with a system 1 shown in Figure 5. Cf course, the systems here can have a plurality of receiver arrays S which are connected to a respective evaluating unit 3 illustrated.

The advantages as have been described above for the system according to the invention are obtained.

A central idea of the present invention is not solely to evaluate the directional information items for echoes arriving at an environment sensor system, but to prevent a temporary "blinding" (in the acoustic sense) of individual receivers due to the presence of interfering sound sources by performing a directional resolution also for interfering sound sources and, depending on the configuration used, being able to ascertain a plurality of directional information items or even an exact position for the interfering sound source. Signals received according to the position of the interfering sound source can thereby be processed in the further course of the evaluation in a predefined manner, e.g. blanked out or disregarded.

Even though the inventive aspects of the present invention have been described in detail with the aid of the exemplary embodinents explained in conjunction with the appended drawing figures, modifications and cortinations of features of the exemplary embodiments set out are possible for a person skilled in the art, without departing from the scope of the present invention, the scope of protection of which is defined by the appended claims.