DE102015200200B4 - Ultrasonic measuring system, means of transport and method for operating an ultrasonic transceiver - Google Patents

Abstract

Method for operating an ultrasonic transceiver (20) comprising the steps
- Transmission (100) of a first signal representing a first code word by means of a first ultrasonic sensor (1) of a first group (G12) of ultrasonic sensors (1-6) in a first measurement cycle,
- Transmission (200) of a second signal by means of a second ultrasonic sensor (2) of the first group (G12),
- receiving (300) echoes of the first signal and the second signal by means of a third ultrasonic sensor (1, 2), and
- Differentiate (400) from the first signal originating parts of the echo from the second signal originating parts by decoding the code word, the second signal having a significantly shorter duration and / or a significantly different amplitude than the first signal.

Description

State of the art

The present invention relates to an ultrasonic measuring system, a means of transportation and a method for operating an ultrasonic transceiver device for a means of transportation. More particularly, the present invention relates to improvements in signal detection and conditioning through coding.

The use of ultrasonic transmitter-receiver devices (“ultrasonic sensors” for short) has been known for many years in automobile construction for detecting the environment and measuring proximity. Driver assistance functions are also often based on ultrasonic sensors, which are typically provided in clusters of 4 to 6 per bumper on the means of transportation (hereinafter “vehicle” for the sake of simplicity).

DE 10 2008 007 667 A1 discloses a method for operating a parking assistance system, in which ultrasonic-based distance sensors are activated in two different modes with temporally different transmission sequences. In particular, it is proposed for the switching to use a dependency on the vehicle speed.

EP 1 105 749 B1 shows a device for detecting objects by means of ultrasonic transceivers, by means of which the transmission signals are provided with an identifier that changes over time, which is changed in particular on the basis of a random function. In order to prevent a waiting time estimated for the evaluation of received echoes from leading to a simultaneous failure of a number of systems and subsequent overlapping again, it is further proposed that a randomly controlled waiting time be provided after a detected overlapping of two systems. The selection of a new carrier frequency to prevent interference between two systems should also be random, in order to prevent the two systems from interfering with one another even after the carrier frequency change.

DE 10 2011 109 830 A1 discloses a method for determining the origin of a received signal received by an ultrasonic sensor of a motor vehicle, in which differently coded transmission signals are examined after receiving their reflection and the code word contained is extracted. The extracted code word is then compared with the code word used to encode the transmission signal. A correlation can therefore be omitted.

Today's ultrasonic systems typically work with a fixed operating frequency in the range of 40 kHz to 50 kHz for transmission and reception. The identical working frequency for all sensors ensures that cross-echo operation is possible, i. H. a sensor can receive echoes on the frequency of the transmitting neighboring sensor. In order to use the cross-echo information correctly in a parking assistance system, it must be clearly assigned to the transmitting sensor. Multiple transmissions from sensors with a clear assignment of the echoes to the sensor is only possible if this can be ensured based on the geometric relationships of the sensor installation positions, e.g. B. Front/rear or central sensors compared to the side-mounted sensors. In today's systems, this limits the measurement update rate of the system (measurement cycles per unit of time), since typically four front or rear sensors have overlapping "fields of vision" or detection areas and therefore cannot transmit simultaneously in one measurement cycle. In addition, the use of only one fixed working frequency results in limitations in the detection robustness, for example due to low interference immunity to ultrasonic signals from other vehicles. It is therefore an object of the present invention to alleviate or eliminate the disadvantages identified above.

Furthermore, the DE 10 2011 120 447 A1 a method for operating an ultrasonic sensor, in which a transmission signal modulated by means of phase jumps is transmitted, a reflected transmission signal is received and the received signal is evaluated with regard to the phase jumps.

In addition, the DE 10 2007 029 959 A1 a method for detecting the environment by means of a pulse emitted by a converter and detecting the reflections, the transmission pulses of simultaneously operated converters being distinguishable by individual modulation

Disclosure of Invention

The object identified above is achieved according to the invention by a method for operating an ultrasonic transceiver. The ultrasonic transceiver can be designed in particular for use in a vehicle (automobile or the like). As described above, it comprises a plurality of ultrasonic sensors which are arranged in relation to one another in such a way that at least their detection ranges (possibility of receiving an echo signal which originates from an adjacent sensor) partially overlap one another. In a first step, we use a first signal representing a first code word a first ultrasonic sensor of a first group of ultrasonic sensors emitted in a first measurement cycle. A first measurement cycle is understood to be such a period of time in which an ultrasonic signal is emitted by the ultrasonic transceiver and a first echo of the signal from the environment is received in the ultrasonic transceiver. According to the invention, the first signal is modeled in such a way that its signal properties are changed over time in a recognizable and reconstructable manner. In other words, the first signal bears a kind of "fingerprint" which enables echoes based on it to be unambiguously assigned to the original ultrasonic sensor. A second signal is then sent into the environment by means of a second ultrasonic sensor from the first group or from another group. The second signal can also have a code word, which then, however, differs from the first signal. Subsequently, echoes of the first signal and the second signal are received by means of a further ultrasonic sensor, it being possible for the further ultrasonic sensor to be the first and/or the second ultrasonic sensor, for example. Alternatively, the first and the second ultrasonic sensor can each be understood as a further ultrasonic sensor in relation to the reception process. Alternatively, the further ultrasonic sensor can be an ultrasonic sensor that is additionally present compared to the first and the second ultrasonic sensor. Optionally, at least the echo of the first signal and/or the echo of the second signal can also be received by a fourth ultrasonic sensor. Subsequently, portions originating from the first signal are differentiated from portions originating from the second signal by decoding the code word. This can be done, for example, by means of a matched filter. In this case, the time profile of the filter is adapted to the time profile of an expected signal, as a result of which echo signal components in the filter output signal that differ greatly from the first signal are suppressed. Each part of the signals contained in the received echo can then be assigned to a corresponding transmission process or ultrasonic sensor as the original sensor, and an examination of the environment, e.g. B. based on the signal propagation time, the echo strength, etc. can be performed according to the prior art. In this way, more ultrasonic signals can be emitted and echoes received per unit of time, as a result of which the spatial and temporal resolution for an ultrasonic transceiver device according to the invention is significantly increased compared to the prior art. The information about the environment becomes more accurate and reliable.

The dependent claims show preferred developments of the invention.

The ultrasonic sensors of the first group are preferably arranged in relation to one another in such a way that they are set up to receive cross echoes from one another. This can apply in particular to all of the ultrasonic sensors in a group. In other words, a member of the group can receive at least one echo from another member of the group, preferably from all members of the group, provided the reflecting object is suitable for this.

The second signal can represent a second code word. In order to achieve good recognition reliability when distinguishing components of the echo originating from the first signal with respect to components of the echo originating from the second signal, the characters of the first code word can each consist of a signal section whose properties over time always differ from the second signal by means of adapted filtering are different. In this way, it is ruled out that characters of code words whose echoes are potentially incident on an identical ultrasonic sensor can superimpose one another in such a way that an unambiguous assignment to an original ultrasonic sensor is prevented. An example of such code words are orthogonal codes. For example, two separate signals can also be used for the first and the second code word. This greatly increases the detection and mapping of the received echoes and allows for better immunity from mutual interference between the ultrasonic sensors.

In particular, it can be ensured that successive time signal sections differ with regard to a fundamental frequency and/or a fundamental frequency curve, in particular with regard to a start frequency and/or a target frequency and/or with regard to a frequency change direction and/or with regard to a frequency change speed and/or with regard to a frequency range (e.g. characterized by a lower and an upper limit frequency or by a start frequency and a target frequency) from each other, so that they can be identified by adapted filtering after receiving an echo. Due to individual or a combination of the aforementioned signal properties, different identifiers or code words for the signals used in the ultrasonic transceiver according to the invention can be clearly identified and distinguished from one another by suitable (digital and/or analog) filtering.

According to the invention, the second signal is characterized by a significantly shorter duration and/or an amplitude that differs significantly from the amplitude of the first signal. In particular, a shorter duration can mean that in the case of short-range detections, results for a clear identification of corresponding echo signals are available more quickly and the short-range detection limit is significantly reduced. As a result, distances to very close surrounding objects can be reported earlier and, if necessary, corresponding warnings can be issued earlier. Even in the case of objects moving relatively in the direction of the ultrasonic sensor system, a warning message can be issued with a longer lead time.

This makes it possible to complete an evaluation of an echo originating from the second signal at a point in time at which an evaluation of the first signal is still ongoing. This can also take place when both the first and the second signal are reflected by an identical surrounding object. In particular, the transmission of a greatly shortened signal can be advantageous if the same ultrasonic sensor is to be used to receive the corresponding echo and its membrane must therefore have fallen below a predefined vibration amplitude before the echo can be reliably identified from the decay signal.

To prevent code-specific interference over a longer period of time, a method can be used which is to be referred to as “code toggling” within the scope of the present invention. In this case, in a second measurement cycle, which in particular immediately follows the first measurement cycle, a third signal representing a third code word is transmitted by means of the first ultrasonic sensor of the first group of ultrasonic sensors. As described above, this first ultrasonic sensor had transmitted the first code word in a previous measurement cycle. If, for example, the first code word and the third code word are in different frequency ranges, in particular disjunctive frequency ranges, narrow-band interference (e.g. due to an external ultrasonic signal) can only interfere with one of the two code words in such a way that its echoes cannot be reliably detected . On the other hand, at least one of the transmitted code words leads to an echo, even if the interference persists, which can be reliably detected and used for environment detection.

Furthermore, the method according to the invention can include sending out a fourth signal representing the first code word by means of a fourth ultrasonic sensor of a second group. The ultrasonic sensors of the first group can be arranged opposite those of the second group in such a way that they are not suitable for receiving echoes which are based on ultrasonic signals originating from the second group. In other words, the first code word is emitted at the same time by the first ultrasonic sensor and the fourth ultrasonic sensor during the first measurement cycle, so that the large number of code words can be reduced and their character spacing can be increased. This increases the reliability of detection. Due to the fact that crosstalk between the first group and the second group cannot occur due to geometric considerations alone, the recognition reliability is in no way reduced by the simultaneous use of the first code word.

Preferably, a travel speed of the ultrasonic transceiver (which is arranged e.g. in an automobile) can be compared with a predefined reference and, in response to the result, a code word to be transmitted by the first ultrasonic sensor in a subsequent measurement cycle can be selected from a predefined plurality of code words. For example, the length of the code word can be adjusted in order to be able to maintain the warning time up to a collision at a cruising speed above the predefined reference by using a short code word or several short code words. As described above, a long code word at a high cruising speed could require detection that is too time-consuming, while the surrounding object and the time of the collision are getting dangerously close in the meantime. In this way, the update speed and the detection range can be improved in this way at the expense of less interference rejection.

According to the invention, it is assumed that the ultrasonic sensors used are able to emit a coded transmission signal and can simultaneously receive and recognize several foreign codes from neighboring sensors. This can be done, for example, by means of linear frequency ramps and the use of correlation methods in the receiving unit. An additional detection robustness reserve can be obtained by additional jittering of the order of the code words used and by additional variation of the codes and by using a stochastic waiting time between the individual transmission patterns (all of the aforementioned properties can be used individually or in any combination with one another). In this way, for example, foreign ultrasound sources or internal interference caused by unwanted reflections are suppressed.

According to a second aspect of the present invention, an ultrasonic measuring system is proposed which has a first group of ultrasonic sensors with a first and a second ultrasonic sensor and a second group of ultrasonic sensors with a further ultrasonic sensor. The ultrasonic sensors of the first group are arranged geometrically opposite those of the second group in such a way that they are not suitable for receiving echoes of signals from the second group. In other words, the reception of cross echoes is (almost) impossible under any technically sensible operating conditions. Furthermore, the ultrasonic measuring system is set up to carry out a method according to one of the preceding claims. The features, combinations of features and the resulting advantages correspond to those of the above-described method according to the invention in such a way that reference is made to the above explanations to avoid repetition.

According to a third aspect of the present invention, a means of transportation, in particular a vehicle (e.g. a car, a van, a truck, an aircraft and/or watercraft) is proposed which has an ultrasonic measuring system according to the second-mentioned aspect of the invention. The means of transportation can use the ultrasonic measurement system to output user information and/or to operate any driver assistance systems. Also with regard to the means of transportation, reference is made to the features, combinations of features and the advantages of the aspects of the invention described above.

Contrary to the state of the art, the present invention does not only propose the jittering and a stochastic waiting time of the transmitter controls of different ultrasonic sensors. Rather, through the skillful selection of codes ("code words") and a corresponding connection of the ultrasonic sensors in the system network as "transmitter", "receiver" or as "transmitter and receiver" to realize the advantages described above, the ultrasonic measuring system is used in such a way that the immediate The close range as well as the far range of the environment can be covered and multiple transmission in overlapping detection areas of the sensors is possible. Optionally, code toggling increases detection reliability in terms of suppressing erroneous object detections.

character list

• 1 eine schematische Systemübersicht eines erfindungsgemäß ausgestalteten Ultraschallmesssystems;
• 2 eine erste Tabelle, welche eine erste Betriebsweise eines erfindungsgemäß ausgestalteten Ultraschallmesssystems repräsentiert;
• 3 eine zweite Tabelle, welche eine alternative Betriebsweise eines erfindungsgemäß ausgestalteten Ultraschallmesssystems repräsentiert;
• 4 eine dritte Tabelle, welche eine alternative Betriebsweise eines erfindungsgemäß ausgestalteten Ultraschallmesssystems repräsentiert;
• 5 eine vierte Tabelle, welche eine alternative Betriebsweise eines erfindungsgemäß ausgestalteten Ultraschallmesssystems repräsentiert;
• 6 eine fünfte Tabelle, welche eine alternative Betriebsweise eines erfindungsgemäß ausgestalteten Ultraschallmesssystems repräsentiert; und
• 7 ein Flussdiagram veranschaulichend Schritte eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens.

Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing is:

• 1 a schematic system overview of an ultrasonic measuring system designed according to the invention;
• 2 a first table, which represents a first mode of operation of an ultrasonic measuring system designed according to the invention;
• 3 a second table, which represents an alternative mode of operation of an ultrasonic measuring system designed according to the invention;
• 4 a third table, which represents an alternative mode of operation of an ultrasonic measurement system designed according to the invention;
• 5 a fourth table, which represents an alternative mode of operation of an ultrasonic measurement system designed according to the invention;
• 6 a fifth table, which represents an alternative mode of operation of an ultrasonic measuring system designed according to the invention; and
• 7 a flow chart illustrating steps of an embodiment of a method according to the invention.

Embodiments of the invention

1 shows a schematic plan view of an exemplary embodiment of an ultrasonic measuring system 20 according to the invention, which has ultrasonic sensors 1, 2, 3, 4, 5, 6 in a bumper of a passenger car 10 as a means of locomotion. The ultrasonic sensors 1, 2, 3, 4, 5, 6 have respective transmission lobes 11, 12, 13, 14, 15, 16. The ultrasonic sensors 1, 2, 3, 4, 5, 6 are each connected via a signal line to a central control device 7 as an evaluation unit. Depending on the surrounding objects, the ultrasonic sensors 1, 2, 3, 4, 5, 6 are only able to a limited extent to be able to receive cross echoes from one another. By way of example, the ultrasonic sensors 1, 2, 3, 4, 5, 6 are divided into groups G12, G23, G34, G45, G56 in order to be able to refer to the possibility or impossibility of cross-echo reception. For example, groups G12 and G45 are arranged at a distance from one another in such a way that echoes based on signals from group G45 cannot be received by ultrasonic sensors 1, 2 of group G12. The tables of 2 until 6 affect operations like them for an array of ultrasonic sensors 1, 2, 3, 4, 5, 6 of 1 can be used.

2 shows a table to illustrate a possible transmit-receive pattern for the ultrasonic sensors 1, 2, 3, 4, 5, 6 (first line of the table) according to in 1 illustrated exemplary arrangement. Below the first line are two further lines representing a first measuring cycle (number 1) and a second (following in time) measuring cycle (number 2). In the cells of the table means
-"s" that the sensor both sends and directly receives echoes in the measurement cycle,
-"r" that the sensor only receives cross echoes in the measurement cycle and does not emit any signals, and
- "s/r" means that the sensor both transmits and receives direct and cross echoes. In the right part of the table for the six ultrasonic sensors 1, 2, 3, 4, 5, 6 (numbering within the first line of all tables accordingly 1 ) and the measuring cycles 1 and 2 respectively entered whether the ultrasonic sensor 1, 2, 3, 4, 5, 6 functions in the measuring cycle as a direct echo receiver "D" and/or as a cross echo receiver "C". The hatchings represent four different code words with which the ultrasonic sensors 1, 2, 3, 4, 5, 6 transmit or are confronted (in the form of echoes). With one exception, the codes used must ensure good mutual suppression: Only the codes that the first sensor sends in the first measurement cycle and the sixth sensor in the second measurement cycle do not have to be particularly suitable for mutual suppression in the example given.

3 shows a possible modification of the in 2 mode of operation shown by the introduction of particularly short signals, which are marked with the lettering "short". Unlike the legend of 2 "short" means that the sensor in question both transmits the short signal and is set up to receive direct echoes, as can be seen from the right half of the table ("short" signals are always within the same measuring cycle and the same ultrasonic sensor 1, 2, 3, 4, 5, 6 received and evaluated).

4 shows a further development of the in 3 illustrated mode of operation, through which the measurement update rate (measurements per unit of time) can be optimized. For this purpose, in each measuring cycle 1 to 4, a short “short” signal is sent out and received by means of two ultrasonic sensors 1, 2, 3, 4, 5, 6 spaced apart from one another. This can, for example, have a short pulse with a fixed frequency, in particular consist of such a pulse. In addition, a further transmission process was provided for the sixth ultrasonic sensor in the second measurement cycle and a further transmission process (each with a reception of direct echoes) was implemented for the first ultrasonic sensor in the fourth measurement cycle. For the inside 4 illustrated operating mode, a good mutual suppression of those codes from each other is required, which are emitted, for example, in the third measurement cycle from the first and second ultrasonic sensors. In addition, good mutual suppression is required for those codes which the fifth and sixth ultrasonic sensors emit in the second measurement cycle.

5 shows an example of a so-called code "toggling" to increase the detection robustness at high update rates. instead of as in 2 shown to implement only two different measurement cycle code word combinations, in the third and fourth measurement cycle the first ultrasonic sensor 1 is operated with that code which was provided in the first and second measurement cycle for the sixth ultrasonic sensor (and vice versa). The same applies to those codes which the second and further ultrasonic sensors or the fourth and fifth ultrasonic sensors have emitted in the first and second measuring cycle. In this way, code-specific errors can be ruled out at least over a period of four measurement cycles.

6 shows an example of code toggling based on the in 3 shown transmission patterns. In this case, the code which the first ultrasonic sensor 1 transmits in the first measurement cycle is replaced after the fourth measurement cycle with a code that has not been used up to now. The same applies to that code which, for example, the fifth ultrasonic sensor 5 transmits in the first measurement cycle. In this way, the code used is changed after four measurement cycles at the latest in order to avoid systematic detection errors over a longer period of time and thus improve collision detection.

7 shows steps of an embodiment of a method according to the invention for operating an ultrasonic transceiver. In step 100 a first signal representing a first code word is transmitted by a first ultrasonic sensor of a first group of ultrasonic sensors and by a fourth ultrasonic sensor of a second group of ultrasonic sensors in a first measuring cycle. In step 200 a second signal is emitted by a second ultrasonic sensor of the first group. In step 300, echoes of the first signal and the second signal are receive another ultrasonic sensor, which is identical to the first ultrasonic sensor. In step 400, portions of the echo originating from the first signal are distinguished from portions originating from the second signal by decoding the code words contained. The decoding of the code words enables a higher measurement signal density per unit of time with error-free recognition and assignment. In step 500, a third signal representing a third code word is emitted by the first ultrasonic sensor of the first group of ultrasonic sensors in a second measurement cycle, whereby code toggling is implemented to fundamentally avoid code-specific recognition errors. In step 600, a travel speed of the ultrasonic transceiver device (eg a means of transportation designed according to the invention) is compared with a predefined reference. In response to the result, in step 700 a short code word to be sent from the first ultrasonic sensor in a subsequent, next measurement cycle is selected from a predefined plurality of code words. If the cruising speed has exceeded the predefined reference, increased use of short code words is initiated, for example, in order to improve the reaction times of the system and thereby optimize the advance warning times.

Claims (11)

Method for operating an ultrasonic transceiver (20) comprising the steps - Transmission (100) of a first signal representing a first code word by means of a first ultrasonic sensor (1) of a first group (G12) of ultrasonic sensors (1-6) in a first measurement cycle, - Transmission (200) of a second signal by means of a second ultrasonic sensor (2) of the first group (G12), - receiving (300) echoes of the first signal and the second signal by means of a third ultrasonic sensor (1, 2), and - Differentiate (400) from the first signal originating parts of the echo from the second signal originating parts by decoding the code word, the second signal having a significantly shorter duration and / or a significantly different amplitude than the first signal. procedure after claim 1 , The ultrasonic sensors (1, 2) of the first group (G12) being spatially arranged in such a way that they are set up to receive cross echoes from one another. procedure after claim 1 or 2 , wherein the second signal represents a second code word. Method according to one of the preceding claims, in which the characters of the first code word each consist of a time signal section whose properties over time can always be distinguished from the second signal by means of adapted filtering. procedure after claim 4 , where successive time signal sections differ from one another with regard to - a fundamental frequency, and/or - a fundamental frequency curve, in particular with regard to - a starting frequency and/or a target frequency and/or - a frequency change direction, and/or - a frequency change speed, and/or - a frequency range. Method according to one of the preceding claims, wherein an evaluation of an echo originating from the second signal has already been completed at a point in time at which the first signal is still being evaluated. A method according to any one of the preceding claims further comprising - Transmission (500) of a third signal representing a third code word by means of the first ultrasonic sensor (1) of the first group (G12) of ultrasonic sensors (1-6) in a second measuring cycle, and/or - Transmission (100) of a fourth signal representing the first code word by means of a further ultrasonic sensor (4) of a second group (G45), the ultrasonic sensors (1, 2) of the first group (G12) being spatially arranged in such a way that they are not suitable to receive echoes from the second group (G45) of signals. A method according to any one of the preceding claims further comprising - Changing an assignment between the code words used and the ultrasonic sensors (1-6) for a subsequent transmission cycle, the changing taking place in particular according to a predefined sequence and/or stochastically. A method according to any one of the preceding claims further comprising - comparing (600) a cruising speed of the ultrasonic transceiver (20) to a predefined reference and responsive thereto - Selecting (700) one of the first ultrasonic sensor (1) to be sent in a next measurement cycle code word from a predefined plurality of code words, in particular a changed length. Ultrasonic measuring system comprising - a first group (G12) of ultrasonic sensors (1, 2) with - a first ultrasonic sensor (1), and - a second ultrasonic sensor (2) and - a second group (G45) of ultrasonic sensors (4, 5) with - a further ultrasonic sensor (4), wherein the ultrasonic sensors (1, 2) of the first group (G12) are spatially arranged in such a way that they are not suitable for receiving echoes of the second group (G45) and wherein the ultrasonic measuring system (20) is set up, to carry out a method according to any one of the preceding claims. Means of locomotion comprising an ultrasonic measuring system (20). claim 10 .

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