DE102020201472B4 - Acoustic localization of an event - Google Patents

Abstract

An acoustic sensor (115) for a vehicle (100), the acoustic sensor (115) comprising: a microphone (205); a first interface (215) for connection to a data bus (240); a second interface (220) for connection to a system clock line (245); a clock generator (240); a processing device (210) which is set up to acquire sensor data of the microphone (205) at points in time which are dependent on a clock rate of the clock generator (260) and to transmit it via the data bus (240); wherein the clock generator (240) is set up in a first operating mode to match the clock provided by the clock generator (260) to a system clock on the system clock line (245), and in a second operating mode on the basis of the clock provided by the clock generator (260) Clock to provide a system clock on the system clock line (245), wherein the acoustic sensor (115) is set up to superimpose a predetermined signal on the detected sensor data in response to a pilot pulse detected on the system clock line (245) in the first operating mode.

Description

The present invention relates to the acoustic localization of an event. In particular, the invention relates to the transmission of synchronized audio data over a data bus.

A large number of different driver assistants can be provided on board a vehicle, in particular a motor vehicle. Some of these assistants can warn a human driver of a danger in the vicinity of the vehicle. For this purpose, the environment can be scanned using different sensors. On the basis of the scanned information, the danger can be determined and an indication of the danger can be output.

In the present case, an event in the vicinity of the vehicle is to be determined by means of an arrangement of acoustic sensors on the vehicle. Each acoustic sensor comprises a microphone and is set up to transmit sensor data provided by the microphone to a control device by means of a data bus. The control device can determine and, in particular, localize the event on the basis of the transmitted sensor data.

To determine and localize the event, it is necessary to examine recorded sensor data in a common time frame of reference. The data bus can delay the transmission of a recorded sensor value by an unknown amount, so that the time reference of the sensor value on the receiver side can be lost. Providing each individual recorded sensor value with a point in time of the recording can massively increase the bandwidth required for the transmission.

the US 020170041127 A1 discloses systems and methods for acoustic gesture recognition. the WO 2015/065792 A1 discloses camera slave controllers with multiple slave identifiers.

An object on which the present invention is based therefore consists in specifying an improved technique for the acoustic localization of an event by means of a distributed system. The invention solves this problem by means of the subjects of the independent claims. Subclaims reproduce preferred embodiments.

According to a first aspect of the present invention, an acoustic sensor for a vehicle comprises a microphone; a first interface for connection to a data bus; a second interface for connection to a system clock line; a clock generator; and a processing device which is set up to acquire sensor data of the microphone at points in time which are dependent on a clock rate of the clock generator and to transmit it via the data bus. The clock generator is configured to match the clock provided by the clock generator to a system clock on the system clock line in a first operating mode, and to provide a system clock on the system clock line based on the clock provided by the clock generator in a second operating mode.

A large number of structurally identical acoustic sensors can be connected to one another by means of a data bus and a system clock line in order to together result in a sensor system which provides the respective microphones with recorded sensor data that are synchronized with one another. The sensor data can in particular be evaluated more precisely by means of a control device connected to the data bus in order to determine and / or localize an acoustic event that can be detected by at least two acoustic sensors. According to the invention, the acoustic sensors are not synchronized via the data bus, which usually cannot guarantee a time-synchronous transmission of information, but via a dedicated system clock line. Which of the acoustic sensors of the sensor system are in the first operating mode, and which ones are in the second operating mode, can be determined dynamically when the sensor system is started.

In one embodiment, the processing device is set up to dynamically determine an identification of the acoustic sensor for communication on the data bus. For this purpose, the processing device can send out an identification request which is either directed to a permanently predetermined subscriber or to a group of subscribers (multicast, broadcast). The identification can then be issued by a control device connected to the data bus. The identification can be used in the manner of an address to send information to the acoustic sensor or from the acoustic sensor to another participant in the data bus, or to receive information on the data bus. Due to the dynamic assignment of the identification, identical acoustic sensors can be used to build a sensor system. The identification can be determined once, for example when the sensor system is started up for the first time, or regularly, for example every time the sensor system is started up.

In a particularly preferred embodiment, the acoustic sensor is set up for connection to a control line, the processing device being set up to control one of the operating modes as a function of a signal on the control line. In particular, the Operating mode can be controlled depending on an identification of the acoustic sensor. For example, numerical identifications can be used and the second operating mode can be assumed by the acoustic sensor that is assigned, for example, the first, the last, the lowest, the highest or a predetermined identification. The control line can be used to switch on the acoustic sensors one after the other in a well-defined sequence, each newly activated acoustic sensor receiving its identification before a further acoustic sensor is switched on. For this purpose, the control line can in particular be provided as a power supply for the acoustic sensor. The control line can be looped through several acoustic sensors of the sensor system in a predetermined order (daisy chain). In this way, the assignment of an identification and / or the control of the operating modes of the acoustic sensors can be controlled economically and reliably.

Using terms common in electrical engineering, an acoustic sensor can be described as a “slave” in the first operating mode and as a “master” in the second operating mode. In a sensor system, it is preferably ensured that exactly one acoustic sensor is configured as the master and the others as slaves.

An acoustic sensor operating as a slave can be set up to synchronize the clock provided by means of its clock generator to a synchronization pulse on the system clock line. Synchronization pulses can be given at regular intervals, for example once per second. By synchronizing, the acoustic sensor can ensure that the clock provided by means of its clock generator is not only as fast as the clocks of the other acoustic sensors, but also has a predetermined phase relationship with them, in particular synchronicity. This can make it easier to classify sensor values over time that were recorded by different acoustic sensors.

The acoustic sensor configured as a master can be set up to regularly provide a synchronizing pulse on the system clock line. A frequency with which the sync pulse is provided can be determined based on the system clock.

For the precise processing of the recorded sensor values, it may be necessary to prove the synchronicity of the acoustic sensors of the sensor system.

According to the invention, the acoustic sensor configured as a slave is set up to superimpose a predetermined signal on the recorded sensor data in response to a pilot pulse recorded on the system clock line. The predetermined signal is usually periodic and can also be called a pilot tone. In the present case, the pilot tone can, for example, be in a frequency range that is detected by the microphone of the acoustic sensor. An exemplary pilot tone can have a frequency of approximately 20 kHz. The frequency of the pilot tone can be selected as a function of the clock rate of the clock generator. Pilot tones from different acoustic sensors can be compared with one another and, in particular, it can be determined whether there is a phase difference between the pilot tones. To this end, it can be determined whether the pilot tones assume the same values at synchronous points in time, in particular the value zero in each case. If the pilot tones are synchronous with one another, then the recorded sensor values of the acoustic sensors are also synchronous with one another and the acoustic event can be determined with a high degree of accuracy.

It is particularly preferred that the pilot tone comprises a sinusoidal signal. The mean value of a sinusoidal signal is zero, so that the recorded sensor values of the microphone are not shifted up or down on average over time, and the sinusoidal signal ideally does not contain any harmonics, so that it can easily be separated from the recorded sensor values after transmission.

An acoustic sensor configured as a master can be set up to provide a pilot pulse on the system clock line in response to a pilot message on the data bus. The pilot message can in particular be transmitted from a control device to the master acoustic sensor. As a result, the control device does not need its own connection to the system clock line. In addition, the pilot pulse can always be given synchronously with the system clock. Points in time at which acoustic sensors configured as slaves activate their pilot tones can be better synchronized with one another.

In addition to a ground connection, the acoustic sensor can have no more than six further connections for connection to another acoustic sensor. The ground connection is usually connected to a body of the vehicle and can be uncritical in terms of signaling. Of the six connections, two can be connected to a serial data bus, two more can be connected to a differential system clock line and the last two can be connected to the looped control line, that is to say comprise an incoming power supply and an outgoing power supply.

The acoustic sensor can be used on board a vehicle by means of a Be equipped with the connector to which the six connections are located. The connector often has to meet special requirements, for example with regard to contact reliability, resistance to aging, watertightness or resistance to vibration. By using no more than six connections, a standard connector can be used which, due to its widespread use, can be relatively inexpensive. A connector with more than six connections can be mechanically significantly larger and considerably more expensive.

According to a second aspect of the present invention, a sensor system comprises a plurality of acoustic sensors described herein, a control device, a data bus and a system clock line. The acoustic sensors are connected to the control device by means of the data bus and to one another by means of the system clock line. The system clock line can be implemented in the manner of a serial bus in that it connects the acoustic sensors to one another in a predetermined order. The control device is preferably set up to evaluate acoustic data that are based on sensor values of the microphones recorded by the acoustic sensors. In addition, the control device can be set up to distribute identifications to the acoustic sensors. In addition, the control device can be set up to configure the acoustic sensors in such a way that exactly one works as a master in the second operating mode and all others work as a slave in the first operating mode.

According to the invention, the control device is set up to recognize a predetermined pattern in the sensor data provided by the acoustic sensors and then to cause the acoustic sensors to superimpose a predetermined signal on each detected sensor data. The predetermined pattern may include an acoustic signature of a predetermined event. This signature can include, for example, a frequency, a bandwidth, a time profile or a volume. Only when the predetermined pattern has been recognized can the superimposition of the predetermined signal be controlled via the recorded sensor data. This can in particular take place in that the control device sends a pilot message to the master acoustic sensor, which can then send a pilot pulse to the remaining acoustic sensors so that they each activate their pilot tones. The recognition of the pattern without the pilot tones allows a fine response to a low acoustic signal, and the evaluation of the superimposed sensor data allows checking whether the sensor data are synchronized with one another. A signal-to-noise ratio (SNR) can be reduced by using the pilot tones, but this can be less disturbing after the pattern has been recognized. This applies in particular to an expected case of a relevant acoustic signal, which can be detected by the acoustic sensors at first quietly and later louder.

The control device is further preferably set up to determine an event from which the received sound originates on the basis of sensor data which have been received by the acoustic sensors and which contain the predetermined signal. The event can in particular include a source that emits sound into the area of the vehicle where the sound can be detected by at least one of the acoustic sensors. The control device can in particular determine a direction, a distance and / or a movement of the event.

According to a third aspect of the present invention, a vehicle comprises a sensor system as described herein. The vehicle can in particular comprise a motor vehicle. The motor vehicle is also preferably designed as a passenger vehicle, alternatively also as a motorcycle, truck or bus.

According to a fourth aspect of the present invention, a method for determining an event in the surroundings of a vehicle by means of a plurality of acoustic sensors which are attached to different points of the vehicle, each include a microphone and are connected to a control device by means of a serial data bus, comprises steps of detecting Sensor values from microphones of the acoustic sensors; transmitting the sensor values from the acoustic sensors to the control device; determining the event based on the transmitted sensor values; controlling the acoustic sensors to superimpose a predetermined signal on their sensor values; and determining the event based on the superimposed sensor values.

The method can preferably be carried out by means of one or more processing devices of an acoustic sensor and / or a processing device of a sensor system described herein. For this purpose, the respective processing device can comprise a programmable microcomputer or microcontroller and the method can be in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the system or the acoustic sensor or vice versa.

It is further preferred that, according to the method, it is determined on the basis of the signal superimposed on the sensor values that the sensor values are closed synchronous times were recorded. If there is a corresponding synchronicity over a predetermined period, it can be assumed that the acoustic sensors record their sensor values synchronously and at the same scanning speeds.

• 1 ein Fahrzeug mit einem Sensorsystem;
• 2 ein Sensorsystem für ein Fahrzeug;
• 3 ein Ablaufdiagramm eines Verfahrens; und
• 4 beispielhafte zeitliche Verläufe an einem Sensorsystem;

darstellt.The invention will now be described in more detail with reference to the accompanying figures, in which:

• 1 a vehicle with a sensor system;
• 2 a sensor system for a vehicle;
• 3 a flow chart of a method; and
• 4th exemplary time courses on a sensor system;

represents.

1 shows a vehicle 100 with a sensor system 105 . The vehicle 100 preferably comprises a motor vehicle, in particular a passenger car, and is furthermore preferably set up for use in public road traffic. The sensor system 105 is set up for an acoustically perceptible event 110 to determine and provide an indication of the event 110 to spend. The event may be preferred 110 can be determined more precisely, in particular with regard to its type, its direction, its distance or its movement relative to the vehicle 100 .

The event 110 can for example comprise a siren, a tone sequence horn, a siren or a similar acoustic signal generator. The event 110 can towards the vehicle 100 be stationary or mobile. In a preferred embodiment, the event 110 recognized in a first phase and localized in a second phase. Optionally, it can be decided in a third phase whether the event 110 an influence on the control of the vehicle 100 has, for example, by an otherwise applicable right of way regulation due to the event 110 is changed. For example, this may be the case if the event 110 includes an ambulance, fire engine, or police force vehicle.

The sensor system 105 comprises several preferably structurally identical acoustic sensors 115 in different places on the vehicle 100 may be attached, and a control device 120 . The acoustic sensors 115 and the control device 120 are preferably by means of a preferably bus-type connection system 125 connected to each other, which are essentially linear in the vehicle 100 can extend. For connecting an acoustic sensor 115 with the connection system 125 can be a connector 130 be provided, which further preferably comprises no more than six separate electrical connections (also called contacts or pins). The connector 130 can be set up, in particular, in the exterior of the vehicle 100 attached acoustic sensor 115 to contact safely and permanently. Acoustic sensors are purely exemplary in the present illustration 115 in a front left, a front right, a rear left and a rear right area of the vehicle 100 and labeled ACS1 through ACS4 for ease of reference.

2 shows a sensor system 105 for a vehicle 100 . In an upper area is a control device 120 shown, and in a lower area several acoustic sensors 115 . The number of acoustic sensors 115 is, as indicated in the right-hand area by broken lines, generally not restricted. Purely by way of example, three acoustic sensors are used in the present figure 115 went out.

An acoustic sensor 115 preferably comprises a microphone 205 , a processing facility 210 , a first interface 215 and a second interface 220 . There are also two connections 225 provided inside the acoustic sensor 115 by means of a switch 230 can be connected to each other.

The microphone 205 can for example be designed as a micromechanical component (MIMS). The processing facility 210 is set up in particular to measure sensor values of the microphone 205 to capture and through the first interface 215 provide. The first interface 215 is for connection to a data bus 240 set up the acoustic sensors 115 and preferably also the control device 120 connects with each other. The data bus 240 is preferably transmitted differentially and comprises two lines. In a preferred embodiment, the data bus 240 be designed as a CAN bus. Any other bus, in particular a serial bus, can, however, also be used.

The second interface 220 is for connection to a system clock line 245 set up. The system clock line 245 can also be transmitted differentially on two lines. The transmission can take place, for example, according to the RS-485 standard, other transmission types or protocols are also possible. A control line 250 is in the present embodiment by the individual acoustic sensors 115 looped through. The control line 250 begins, for example, with an energy supply 255 that board the vehicle 100 for example can be applied to terminal 30. The control line runs from there 250 to the acoustic sensor shown on the left 115 . Only when that counter 230 is closed, energy is from the power supply 255 to the next (here the middle) acoustic sensor 115 transfer. The switches 230 are in an open position when idle, so that an acoustic sensor 115 can be switched on one after the other. As will be explained in more detail below, it is preferred that an acoustic sensor 115 When energy arrives, its own identification for communication on the data bus 240 determined and only then his switch 230 closes to a possibly following acoustic sensor 115 to provide with energy. One for the energy supply 255 required ground connection 235 for example with terminal 31 of the vehicle 100 can be connected to each of the acoustic sensors 115 be provided.

Also includes each acoustic sensor 115 a clock generator 260 , which is set up to set a clock for the respective acoustic sensor 115 provide. The processing facility 210 uses this clock to determine when a sensor signal from the microphone 205 recorded and via the data bus 240 to the control device 120 should be transmitted. The clock generator 260 preferably comprises a quartz or another resonant circuit of sufficient quality. About internal clocks of various acoustic sensors 115 to synchronize with each other, it is proposed to use one of the acoustic sensors 115 operate as a master and the others as slaves. The master acoustic sensor 115 provides based on the from its clock generator 260 provided clock a system clock on the system clock line 245 ready. An acoustic sensor configured as a slave 115 equals the speed of its clock generator 260 on the basis of an over the system clock line 245 received system clock. The adjustment can be carried out, for example, by means of a locked phase shifter (phase locked loop, PLL).

To the clock generators 245 Set not only to the same speed, but also to the same phases, can be set periodically via the system clock line 245 a sync pulse can be transmitted. This can in particular from the master acoustic sensor 115 are provided, for example at equal time intervals. The clock of a clock generator 260 can for example be set by means of the PLL in such a way that a rising edge of the system clock is on the system clock line 245 temporally with a rising edge of a local clock of the acoustic sensor 115 coincides. Instead of a rising edge, a falling edge can also be viewed on one and / or both sides.

A localization of the event 110 may require sampling times of the acoustic sensors 115 are safely synchronized with each other. To check this, any clock generator can 260 be set up to send a predetermined signal to the recorded sensor values of its own microphone 205 to be superimposed before the sensor values via the data bus 240 be transmitted. The predetermined signal preferably comprises a pilot signal, which can in particular comprise a pure sine tone as possible, the frequency of which is preferably simply derived from the clock of the local clock generator 260 can be derived. An exemplary pilot tone has a frequency of approx. 20 kHz. The pilot tone can be through an acoustic sensor 115 be switched on exactly when on the system clock line 245 there is a pilot pulse. The pilot tone can be switched off again when the pilot pulse is no longer present. The control device 120 is preferably set up to emit pilot tones from the acoustic sensors 115 in terms of signaling from the respectively provided sampled sensor values of the microphones 205 to separate. Are the pilot tones of the acoustic sensors 115 synchronous, for example because they have their zero crossings at identical measuring times, there is synchronicity between the measured values provided by the acoustic sensors 115 given. The event 110 can then be determined more precisely on the basis of the measured values received. In particular, there can be a direction from which the event 110 on the acoustic sensors 115 acts, can be determined on the basis of differences in transit time of the acoustic signal. The transit time differences are usually shown by phase differences in the measurement data streams of the individual acoustic sensors 115 .

The use of the pilot tone can worsen a signal-to-noise ratio, so that in particular a low acoustic signal of the event 110 difficult to see. It is therefore suggested that the event 110 first to be determined on the basis of recorded sensor values that are not overlaid with a pilot tone. This allows a sensitive determination of the event 110 take place. In particular, a predetermined pattern based on a predetermined event 110 indicates improved can be found in the data streams.

Could the pattern from the controller 120 can be determined via the data bus 240 a pilot message to the acoustic sensor configured as master 115 send. The master acoustic sensor 115 can then send the pilot pulse to the system clock line 245 activate. It can thus be ensured that the control device 120 controls the activation and deactivation of the pilot tone itself, so that the pilot tone can be better taken into account during processing.

To transmit the system clock, a sync pulse and a pilot pulse on the system clock line 245 it is suggested to use different pulse ratios. For example, a square wave signal can be used whose rising edges always have the same time intervals. If a pulse ratio on / off falls below a predetermined threshold value, for example 30%, a synchronous pulse may be present. If the ratio exceeds a second predetermined threshold value, for example approx. 70%, a pilot pulse can be present. Other assignments are also possible and threshold values can also be selected differently.

3 shows a flow chart of a method 300 , in particular in connection with a sensor system 105 can be executed. It deals with the procedure 300 mainly the control of the acoustic sensors 115 .

In one step 305 can identify the acoustic sensors 115 of the sensor system 105 to be determined. This is done by every acoustic sensor 115 assigned a unique identification. Acoustic sensors are preferred 115 switched on one after the other in a sequence determined by their wiring and inquire in each case with the control device 120 or another device provided for this purpose, their identification before the next acoustic sensor 115 turn on in the order.

One of the acoustic sensors is preferably used in parallel with the determination of the identifications 115 designated as masters and the others as slaves. For example, the acoustic sensor 115 , who is the first to receive his identification, can be configured as the master. For example, numerical identifiers can be assigned in ascending order and as soon as all acoustic sensors 115 configured, everyone can determine whether they have the smallest identification and thus work as a master.

An acoustic sensor configured as a slave 115 can be done in one step 310 a system clock on the system clock line 245 determine and one internally by means of its clock generator 260 adjust the generated clock to this. Preferably only when the matching has been successful with a predetermined quality, it can be done in one step 315 a measurement can be carried out. A sensor value of the microphone 205 can be recorded and the recorded sensor value can be transmitted via the data bus 240 to the control device 120 be transmitted. The step 315 can be repeated periodically in the manner of an endless loop depending on the specific cycle.

In one step 320 a sync pulse can be determined. The sync pulse is preferred over the system clock line 245 from the master acoustic sensor 115 transmitted. The clock generator 260 of a slave acoustic sensor 115 can respond to the received sync pulse in one step 325 be synchronized. Subsequently, with the scanning and transmission of sensor values in step 315 to be continued.

In one step 330 can be a pilot pulse on the system clock line 245 to be determined. The pilot pulse can also be sent by the master acoustic sensor 115 on the system clock line 245 be provided. In response to the pilot pulse, the slave acoustic sensor can 115 in one step 335 generate a predetermined signal, in particular a pilot tone, and superimpose it on the detected sensor values. The pilot tone can only be superimposed on the sensor values as long as the pilot pulse is on the system clock line 245 can be captured. Alternatively, the pilot tone can also be generated by corresponding signals on the system clock line 245 can be switched on and off in a dedicated manner.

In one step 340 can sensor signals from one or more acoustic sensors 115 from the control unit 120 can be received and evaluated. The evaluation can take place in different phases and a transition between the phases can be made by the control unit 120 be controlled, in particular by transmitting a control message to the acoustic sensor configured as a master 115 via the data bus 240 .

The acoustic sensor configured as master 115 can be done in one step 350 its own clock by means of its clock generator 260 and on this basis the system clock on the system clock line 245 provide. Then he can do it in one step 355 that the step 315 of a slave acoustic sensor 115 can correspond to his microphone 205 scan and recorded sensor values on the data bus 240 to the control device 120 to transfer. It can be time or event-controlled in one step 360 a sync pulse on the system clock line 245 provide. He can also do it in one step 365 a pilot pulse on the system clock line 245 provide. The step 365 takes place preferably after from the control device 120 a message to the master acoustic sensor 115 which contains a pilot message, i.e. a request for pilot tones in the data streams of the acoustic sensors 115 to use.

4th shows exemplary time courses on a sensor system 105 . A time is plotted in the horizontal direction. A system clock MC is shown in the upper area, which is on the system clock line 245 is transmitted. These include acoustic sensors for example 115 with the designations ACS1, ACS2 and ACS3 in each case chronological progressions 405 represented by provided sensor values.

In the present embodiment, the system clock MC comprises a square-wave signal with a pulse duty factor of approximately 50%. In a first period of time 410 the pulse duty factor is significantly lower, for example approx. 10%, and in a second time segment 415 significantly higher, for example approx. 90%. The first paragraph 410 can be used as a sync pulse and the second time segment 415 be defined as a pilot pulse. The exact synchronization time of the first section 410 can for example be the second rising edge within the first section 410 be.

In a corresponding manner, the decisive point in time of the pilot pulse for the rising edge can be after two periods with the increased pulse duty factor, as shown. Other reference times can be defined in a similar way.

It can be seen that after a point in time t1 at which the pilot pulse of the second section 415 takes effect every course 405 one pilot tone each of the sensor values of the acoustic sensors ACS1 to ACS3 420 is superimposed. The acoustic sensors 115 provide the sensor values overlaid with the pilot tones via the data bus 240 to the control device 120 ready. The control device 120 can do the pilot tones 420 extract from the incoming sensor data.

The individual acoustic sensors 115 put their pilot tones 420 each on the basis of their clock generators 245 ready. The pilot tones 420 of the individual acoustic sensors 115 can only have the same frequencies and phase if the clock generators 245 the acoustic sensors 115 run at exactly the same speed and synchronized with each other, i.e. are in phase with each other. Should have two frequency generators 245 not be synchronized, so are the pilot tones 420 at the control device 120 not in phase. Assign two frequency generators 245 If the frequencies are not exactly the same, their corresponding wavelengths are different and the pilot tones are phase inequality 420 can be observed periodically. It is preferred on the part of the control device 120 examined whether the pilot tones 420 have mutually synchronous zero crossings.

List of reference symbols

100

vehicle

105

Sensor system

110

acoustically perceptible event

115

Acoustic sensor

120

Control device

125

Connection system

130

Connectors

205

microphone

210

Processing facility

215

first interface (to the data bus)

220

second interface (to the system clock line)

225

Connection (to control line)

230

counter

235

Ground connection

240

Data bus

245

System clock line

250

Control line

255

power supply

260

Clock generator

300

procedure

305

Determine ID

310

Determine the system clock, adjust your own clock

315

Sampling the microphone, transmitting the sensor value

320

Determine the sync pulse

325

synchronize your own clock

330

Determine the pilot pulse

335

Apply pilot tone

340

Evaluation of sensor values

350

Provide your own cycle, generate system cycle

355

Sampling the microphone, transmitting the sensor value

360

Provide sync pulse

365

Provide pilot pulse

405

Sensor value (history)

410

first section

415

second part

420

Pilot tone

Claims (13)

An acoustic sensor (115) for a vehicle (100), the acoustic sensor (115) comprising: a microphone (205); a first interface (215) for connection to a data bus (240); a second interface (220) for connection to a system clock line (245); a clock generator (240); a processing device (210) which is set up to acquire sensor data of the microphone (205) at points in time which are dependent on a clock rate of the clock generator (260) and to transmit it via the data bus (240); wherein the clock generator (240) to it is set up, in a first operating mode, to match the clock provided by the clock generator (260) to a system clock on the system clock line (245), and in a second operating mode, based on the clock provided by the clock generator (260), a system clock on the system clock line ( 245), the acoustic sensor (115) being set up to superimpose a predetermined signal on the detected sensor data in the first operating mode in response to a pilot pulse detected on the system clock line (245). Acoustic sensor (115) Claim 1 , wherein the processing device (210) is set up to dynamically determine an identification of the acoustic sensor (115) for communication on the data bus (240). Acoustic sensor (115) Claim 1 or 2 , further wherein the acoustic sensor (115) is set up for connection to a control line (250), and the processing device (210) is set up to control one of the operating modes as a function of a signal on the control line (250). Acoustic sensor (115) according to one of the preceding claims, wherein the acoustic sensor (115) is set up in the first operating mode to synchronize the clock provided by means of the clock generator (260) to a sync pulse on the system clock line (245). Acoustic sensor (115) according to one of the preceding claims, wherein the acoustic sensor (115) is set up to regularly provide a synchronizing pulse on the system clock line (245) in the second operating mode. Acoustic sensor (115) according to any one of the preceding claims, wherein the signal comprises a sinusoidal signal. Acoustic sensor (115) according to one of the preceding claims, wherein the acoustic sensor (115) is set up to provide a pilot pulse on the system clock line (245) in response to a pilot message on the data bus (240) in the second operating mode. Acoustic sensor (115) according to one of the preceding claims, comprising a ground connection (235) and no more than six further connections for connection to another acoustic sensor (115). Sensor system (105), comprising a plurality of acoustic sensors (115) according to one of the preceding claims; a controller (120); and a data bus (240); wherein the acoustic sensors (115) are connected to the control device (120) by means of the data bus (240); and a system clock line (245) to which the acoustic sensors (115) are connected, the control device (120) being set up to recognize a predetermined pattern in the sensor data provided by the acoustic sensors (115) and then to cause the acoustic sensors ( 115) superimpose each acquired sensor data with a predetermined signal. Sensor system (105) Claim 9 wherein the control device (120) is set up to determine, on the basis of the sensor data of the acoustic sensors (115) containing the predetermined signal, an event which causes the predetermined pattern. Vehicle (100) comprising a sensor system (105) according to Claim 9 or 10 . Method (300) for determining an event in the vicinity of a vehicle (100) by means of a plurality of acoustic sensors (115) which are attached to different locations on the vehicle (100), each comprising a microphone (205) and by means of a serial data bus (240) a control device are connected; the method comprising the following steps: acquiring (315, 355) sensor values from microphones (205) of the acoustic sensors (115); Transmitting (315, 355) the sensor values from the acoustic sensors (115) to the control device; Determining the event based on the transmitted sensor values; Controlling (330, 365) the acoustic sensors (115) to superimpose their sensor values with a predetermined signal; and determining the event based on the superimposed sensor values. Method (300) according to Claim 12 , wherein it is determined on the basis of the signal superimposed on the sensor values that the sensor values were recorded at synchronous points in time.

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