CN105785377B

CN105785377B - Ultrasonic measuring system, movement mechanism and method for operating an ultrasonic transceiver

Info

Publication number: CN105785377B
Application number: CN201610011953.7A
Authority: CN
Inventors: A·克洛茨; T·赖纳; M·舒曼
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-01-09
Filing date: 2016-01-08
Publication date: 2021-04-20
Anticipated expiration: 2036-01-08
Also published as: DE102015200200B4; DE102015200200A1; GB2534034A; CN105785377A; GB2534034B; GB201600299D0; FR3031596B1; FR3031596A1

Abstract

The invention relates to an ultrasonic measuring system, a movement mechanism and a method for operating an ultrasonic transmitter-receiver unit. The method comprises the following steps: transmitting a first signal representing a first code word in a first measurement period by means of a first ultrasonic sensor of the first set of ultrasonic sensors; transmitting a second signal with a second ultrasonic sensor of the first group; receiving echoes of the first signal and the second signal with a third ultrasonic sensor; the part of the echo from the first signal is distinguished from the part of the echo from the second signal by means of decoding of the code word.

Description

Ultrasonic measuring system, movement mechanism and method for operating an ultrasonic transceiver

Technical Field

The invention relates to an ultrasonic measuring system, a movement mechanism and a method for operating an ultrasonic transceiver for a movement mechanism. The invention also relates in particular to improvements in signal recognition and preprocessing by coding.

Background

The use of ultrasonic transmitting and receiving devices (ultrasonic sensors for short) in automotive engineering has been known for many years for environmental recognition and distance measurement. The driver assistance function is also frequently based on ultrasonic sensors, which are usually arranged on the movement mechanism (hereinafter "vehicle" for the sake of simplicity) in groups of 4 to 6 for each safety lever.

DE 102008007667a1 discloses a method for operating a parking assistance system, in which an ultrasound-based distance sensor is activated in two different modes in a temporally different transmission sequence. Especially for the conversion proposal, the dependence of the vehicle speed is taken into account.

EP 1105749B 1 shows a device for detecting objects by means of an ultrasonic transceiver, by which a transmit signal is provided with a temporally changing identifier, which changes in particular according to a random function. In order to prevent the estimated waiting time for the evaluation of the received echoes from causing simultaneous interruption and subsequent superposition of a plurality of systems, it is further proposed that a randomly controlled waiting time be provided after the detected superposition of two systems. The selection of the new carrier frequency for preventing interference of the two systems should also be made randomly in order to prevent the two systems from also interfering with each other after the carrier frequency has changed.

DE 102011109830 a1 discloses a method for determining the origin of a received signal received by an ultrasonic sensor of a motor vehicle, wherein after receiving its reflection, differently coded transmitted signals are investigated and the contained code words are extracted. The extracted code words are then compared with the code words applied for the transmission signal coding. The correlation can be ignored.

Today's ultrasound systems typically operate with a fixed operating frequency in the range of 40kHz to 50kHz for both transmit and receive operation. The same operating frequency for all sensors ensures that a cross-echo operation is possible, i.e. the sensor can receive echoes at the frequency of the transmitting adjacent sensor. In order to use the cross-echo information correctly in a parking assistance system, an unambiguous assignment to the transmitting sensor is necessary. Multiple transmissions of the sensors with an unambiguous assignment of the echoes to the sensors is only possible if this can be ensured on the basis of the geometric relationships of the sensor mounting locations, for example front/rear or intermediate sensors with respect to side-mounted sensors. This limits the measurement update rate (measurement period per unit time) of the system in today's systems, since typically four front or rear sensors have overlapping "visibility areas" or detection areas and therefore cannot transmit in one measurement period at the same time. Furthermore, by using only one fixed operating frequency, limitations arise with regard to detection robustness, for example due to the low interference immunity with respect to the ultrasonic signals of other vehicles. It is therefore an object of the present invention to mitigate or eliminate the previously recognized disadvantages.

Disclosure of Invention

According to the invention, the previously recognized task is solved by a method for operating an ultrasound transceiver. The ultrasound transceiver device can be configured in particular for use in vehicles (motor vehicles, etc.). The ultrasonic transmitting and receiving device includes a plurality of ultrasonic sensors as described above, and the plurality of ultrasonic sensors are arranged with respect to each other such that at least detection regions thereof (the possibility of receiving echo signals from adjacent sensors) partially overlap each other. In a first step, a first signal representing a first code word is transmitted in a first measuring period by means of a first ultrasonic sensor of the first group of ultrasonic sensors. The first measurement cycle is to be understood as a time period in which an ultrasound signal is transmitted by the ultrasound transceiver and a first echo of a signal from the surroundings is received in the ultrasound transceiver. According to the invention, the first signal is modulated in such a way that its signal behavior over time is identifiable and reconstructably changeable. In other words, the first signal carries a kind of "fingerprint" which enables an unambiguous assignment of the echo based thereon to the original ultrasound sensor. Subsequently, a second signal is transmitted into the surroundings by means of a second ultrasonic sensor of the first group or of a further group. The second signal may likewise have a code word, which is different from the first signal. The echoes of the first and second signals are then received by means of a third ultrasonic sensor, which may be, for example, a first and/or a second ultrasonic sensor. Alternatively, the first and second ultrasonic sensor reference reception processes can also be understood as a third ultrasonic sensor, respectively. Alternatively, the third ultrasonic sensor may be an ultrasonic sensor additionally present with respect to the first and second ultrasonic sensors. Optionally, at least the echo of the first signal and/or the echo of the second signal may additionally be received by a fourth ultrasound sensor. The part from the first signal is then distinguished from the part from the second signal by means of decoding of the code words. This can be achieved, for example, by means of matched filtering (matched filter in english). In this case, the time profile of the filter is adapted to the time profile of the expected signal, so that echo signal portions which differ strongly from the first signal are suppressed in the filter output signal. Each of the portions of the signals contained in the received echoes can then be assigned to a corresponding transmission process or to an ultrasound sensor as a raw sensor and the investigation of the surroundings can be carried out according to the prior art, for example on the basis of signal propagation time, echo intensity, etc. In this way, more ultrasound signals can be transmitted and more echoes can be received per unit time, thereby significantly increasing the spatial and temporal resolution of the ultrasound transceiver device according to the invention over the prior art. Here, the information about the surroundings becomes more accurate and more reliable.

The dependent claims show preferred embodiments of the invention.

Preferably, the ultrasound sensors of the first group are spatially arranged in such a way that they are provided for receiving cross echoes from one another. This may be particularly applicable to all ultrasonic sensors of a group. In other words, one member of the group may at least receive echoes of another member of the group, preferably of all members of the group, as long as the reflecting object is suitable for this.

The second signal may represent a second codeword. In order to obtain good recognition security when distinguishing the part from the first signal from the part of the echo from the second signal, the markings of the first code word can each consist of a signal section whose temporal behavior can always be distinguished from the second signal by means of a matched filtering. In this way, it is excluded: the markings of the code words, the echoes of which potentially impinge in the same ultrasonic sensor, may be superimposed on one another in such a way that a clear assignment to the original ultrasonic sensor is prevented. One example of such a codeword is an orthogonal code. For example, two mutually separate signals may also be used for the first and second code words. This greatly improves the identification and assignment of the received echoes and enables a better immunity against mutual interference of the ultrasound sensors.

In particular, it can be ensured that successive time signal sections are distinguished from one another with respect to the fundamental frequency and/or the fundamental frequency profile, in particular with respect to the starting frequency and/or the target frequency and/or with respect to the direction of the frequency change and/or with respect to the speed of the frequency change and/or with respect to the frequency range (for example, marked by the lower boundary frequency and the upper boundary frequency or by the starting frequency and the target frequency) in order to be able to identify them after the reception of the echo by means of adapted filtering. Different identifiers or code words for the signals used in the ultrasound transceiver according to the invention can be unambiguously identified and distinguished from one another by suitable (digital and/or analog) filtering on the basis of individual signal properties or combinations of the above-mentioned signal properties.

The second signal may be characterized by, for example, a significantly shorter duration and/or a significantly different amplitude than the amplitude of the first signal. In particular, the shorter duration can result in faster results for unambiguous detection of the corresponding echo signals in the case of near field detection and in a significantly reduced near field detection limit. As a result, the distance to very close surrounding objects can be informed earlier and corresponding warnings can be output earlier if necessary. In the case of objects that are in relative motion in the direction of the ultrasound sensor system, a warning message can be output with a greater time advance

In this case, it is possible to: the evaluation of the echo from the second signal is also ended at a point in time which lasts. This may also occur when not only the first signal but also the second signal is reflected by the same surrounding object. The transmission of a particularly strongly shortened signal can be advantageous when the same ultrasonic sensor is to be used for receiving the corresponding echo and therefore the diaphragm of the ultrasonic sensor must not exceed a predefined vibration amplitude before a reliable identification of the echo with respect to the oscillation damping signal can be achieved.

In order to prevent Code-specific interference over a longer period of time, a method may be used, which in the context of the present invention shall be referred to as "Code switching". In this case, a third signal representing a third code word is transmitted by means of a first ultrasonic sensor of the first group of ultrasonic sensors in a second measuring cycle, which in particular follows the first measuring cycle. The first ultrasonic sensor transmits the first codeword as described above in the previous measurement period. As long as, for example, the first code word and the third code word are located in different frequency ranges, in particular in separate frequency ranges, a narrowband disturbance (for example by means of a further ultrasound signal) can disturb only one of the two code words in such a way that a reliable detection of its echo cannot be achieved. In contrast, in the event of continued interference, at least one of the transmitted code words also leads to an echo, which can be reliably detected and used for the detection of the surroundings.

The method according to the invention may further comprise transmitting a fourth signal representative of the first code word by means of a fourth ultrasonic sensor of the second group. The ultrasonic sensors of the first group may be arranged relative to the ultrasonic sensors of the second group such that they are not suitable for receiving echoes based on ultrasonic signals from the second group. In other words, the first code word is transmitted simultaneously by the first ultrasonic sensor and the fourth ultrasonic sensor during the first measurement period, so that the number of code words can be reduced and their marking distance increased. This improves the security of identification. The identification security is never reduced by the simultaneous application of the first code word, based on the fact that crosstalk between the first and second groups is already not able to occur due to geometrical considerations.

Preferably, the cruising speed of the ultrasound transceiver (which is arranged, for example, in a motor vehicle) can be compared with a predefined reference and, in response thereto, a code word to be transmitted in a temporally successive measuring cycle by the first ultrasound sensor is selected from a predefined plurality of code words. For example, the length of the code words can be adapted in order to be able to maintain a warning time until a collision by using a short code word or a plurality of short code words if the cruising speed is higher than a predefined reference. As described above, long code words may require too time-consuming detection at high cruising speeds, during which the surrounding objects and the impact times move dangerously close. In this way, the update speed and the detection region can be improved in this way at the expense of less interference suppression.

It is assumed according to the invention that the ultrasonic sensor used has the ability to transmit a coded transmission signal and to be able to simultaneously receive and recognize a plurality of strange codes of adjacent sensors. This can be achieved, for example, by linear frequency ramps and the use of correlation methods in the receiving unit. Additional detection robustness margins can be obtained by additional dithering (Jitter) of the order of the applied codewords and by additional variation of the code and by application of random latencies between the individual transmission modes (all of the above characteristics can be applied individually or in any combination with each other). In this way, e.g. other ultrasound sources or self-interference triggered by unwanted reflections can be suppressed.

According to a second aspect of the invention, an ultrasonic measuring system is proposed, which has a first set of ultrasonic sensors with a first ultrasonic sensor and a second set of ultrasonic sensors with a third ultrasonic sensor. The first group of ultrasonic sensors is geometrically arranged relative to the second group of ultrasonic sensors such that the first group of ultrasonic sensors is not suitable for receiving echoes of the signals of the second group. In other words, the reception of cross-echoes is (nearly) excluded under any technically feasible use condition. Furthermore, the ultrasonic measurement system is provided for implementing the method according to any of the preceding claims. The features, feature combinations and advantages derived therefrom correspond in a manner which is obvious to the features, feature combinations and advantages derived therefrom of the method according to the invention described above, so that reference can be made to the above-described embodiments in order to avoid repetitions.

According to a third aspect of the invention, a movement apparatus, in particular a vehicle (for example a passenger car, a transport vehicle, a load wagon, an aircraft and/or a ship), is proposed, which has an ultrasonic measuring system according to the second aspect of the invention. The movement mechanism can use the ultrasonic measuring system for the output of user information and/or for the operation of any driver assistance system. Reference is also made to the features, combinations of features and advantages of the aspects of the invention described above in relation to the movement mechanism.

In contrast to the prior art, the present invention does not only address jitter and a random latency of the transmitter control of the different ultrasonic sensors. In contrast, the ultrasound measurement system is also used to achieve the above-described advantages by a smart selection of the code ("code word") and the wiring of the ultrasound sensor in the system combination as a "transmitter", "receiver" or "transmitter and receiver", in such a way that the immediate near area and the far area of the surroundings can be covered and multiple transmissions in the overlapping detection areas of the sensor can be achieved. Optionally, the detection safety is increased by code switching in the sense of suppression of erroneous object recognition.

Drawings

Embodiments of the present invention are described in detail below with reference to the accompanying drawings. The figures show:

FIG. 1: a schematic system overview of an ultrasound measurement system configured in accordance with the present invention;

FIG. 2: a first table representing a first mode of operation of an ultrasonic measurement system constructed in accordance with the present invention;

FIG. 3: a second table representing an alternate mode of operation of an ultrasonic measurement system constructed in accordance with the present invention;

FIG. 4: a second table representing an alternate mode of operation of an ultrasonic measurement system constructed in accordance with the present invention;

FIG. 5: a fourth table representing an alternate mode of operation of an ultrasonic measurement system constructed in accordance with the present invention;

FIG. 6: a fifth table representing an alternate mode of operation of an ultrasonic measurement system constructed in accordance with the present invention;

FIG. 7: a flow chart illustrating the steps of one embodiment of a method according to the present invention.

Detailed Description

Fig. 1 shows a schematic top view of an exemplary embodiment of an ultrasonic measuring system 20 according to the invention with

ultrasonic sensors

1, 2, 3, 4, 5, 6 in the bumper of a passenger car 10 as a movement mechanism. The

ultrasound 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 conditionally able to receive cross-echoes from one another. The

ultrasound sensors

1, 2, 3, 4, 5, 6 are illustratively divided into groups G12, G23, G34, G45, G56 so that the possibility or impossibility of cross-echoes can be involved. For example, groups G12 and G45 are arranged at such a distance from one another that reception of an echo based on the signal of group G45 cannot be received by the

ultrasound sensors

1, 2 of group G12. The tables of fig. 2 to 6 relate to the operating mode, which can be used for the arrangement of the

ultrasonic sensors

1, 2, 3, 4, 5, 6 of fig. 1.

Fig. 2 shows a table for illustrating one possible transmit-receive mode of the

ultrasonic sensors

1, 2, 3, 4, 5, 6 (first row of the table) corresponding to the exemplary arrangement shown in fig. 1. Two further rows representing a first measuring period (number 1) and a second (temporally successive) measuring period (number 2) are shown below the first row. In the cells of the table:

"s" indicates that the sensor is not only sending but also receiving direct echoes during the measurement cycle;

"r" indicates that the sensor receives only the cross echo and does not transmit a signal during the measurement period;

"s/r" means that the sensor not only transmits but also receives direct echoes and cross-echoes during the measurement cycle.

In the right part of the table, it is recorded for the six

ultrasonic sensors

1, 2, 3, 4, 5, 6 (the numbers in the first row of all tables correspond to fig. 1) and the

measurement cycles

1 and 2, respectively, whether the

ultrasonic sensors

1, 2, 3, 4, 5, 6 act as direct echo receivers "D" and/or cross echo receivers "C" in the measurement cycle. The shading represents four different code words with which the

ultrasonic sensor

1, 2, 3, 4, 5, 6 transmits or faces (in the form of echoes) the four code words. Here, the codes used must respectively guarantee good mutual inhibition, with the following exceptions: the codes that only the first sensor has to transmit in the first measuring period and the sixth sensor in the second measuring period are not particularly suitable for mutual suppression in the listed examples.

Fig. 3 shows a possible improvement of the operating mode shown in fig. 2 by introducing a particularly short signal, which is indicated by the character "short". In contrast to the illustration in fig. 2, "short" indicates that the relevant sensor both transmits the short signal and is set up for the reception of the direct echo, as this is derived from the right-hand part of the table ("short" signals are received and evaluated in the same measurement cycle and in the

same ultrasound sensor

1, 2, 3, 4, 5, 6, respectively).

Fig. 4 shows a further development of the operating mode illustrated in fig. 3, by means of which the measurement update rate (measurement process per unit time) can be optimized. For this purpose, a short signal "short" is transmitted and received in each measuring cycle 1 to 4 by means of two

ultrasonic sensors

1, 2, 3, 4, 5, 6 which are spaced apart from one another. The signal may have, for example, short pulses with a fixed frequency, in particular consist of the pulses. In addition, a further transmission process is provided for the sixth ultrasonic sensor in the second measuring cycle and a further transmission process (in each case with reception of a direct echo) is carried out for the first ultrasonic sensor in the fourth measuring cycle. A good mutual suppression of the codes which are transmitted by the first and second ultrasonic sensors, for example, in the third measuring cycle is required for the operating mode illustrated in fig. 4. Additionally, good mutual rejection is required for the codes transmitted by the fifth and sixth ultrasonic sensors in the second measurement period.

Fig. 5 shows an example of a so-called code "handover" for improving the detection robustness in case of a high update rate. Instead of implementing only two different measuring cycle code word combinations as shown in fig. 2, in the third and fourth measuring cycles the first ultrasonic sensor 1 is operated with a code which is provided for the sixth ultrasonic sensor in the first and second measuring cycles (and vice versa). The same applies to the code which the second and third ultrasonic sensor or the fourth and fifth ultrasonic sensor transmit in the first and second measuring cycles. In this way, code-specific errors can be excluded at least for the duration of four measurement cycles.

Fig. 6 shows an example of code switching based on the transmission mode shown in fig. 3. The code transmitted by the first ultrasonic sensor 1 in the first measuring cycle is replaced by a code which has not been used until now after the fourth measuring cycle. The same applies to codes which are transmitted by the fifth ultrasonic sensor 5, for example, in the first measuring cycle. In this way, the replacement of the used code takes place after four measurement cycles at the latest, in order to avoid systematic recognition errors over a longer period of time and thus to improve collision recognition.

Fig. 7 shows the steps of an exemplary embodiment of a method for operating an ultrasound transceiver device according to the present invention. In step 100, a first signal representing a first code word is transmitted in a first measuring cycle by means of a first ultrasonic sensor of the first group of ultrasonic sensors and by means of a fourth ultrasonic sensor of the second group of ultrasonic sensors. In step 200, a second signal is transmitted by means of a second ultrasonic sensor of the first group. In step 300, echoes of the first signal and of the second signal are received by means of a third ultrasonic sensor, which is identical to the first and second ultrasonic sensors. In step 400, the part of the echo from the first signal and the part of the echo from the second signal are distinguished by means of decoding of the contained code word. The decoding of the code words enables a higher measured signal density per unit time without also erroneous recognition and allocation. In step 500, a third signal representing a third code word is transmitted in a second measuring period by means of a first ultrasonic sensor of the first group of ultrasonic sensors, thereby enabling a code switch for the purpose of avoiding code-specific identification errors in principle. The cruising speed of an ultrasonic sensor transceiver (e.g., of a motion mechanism configured according to the present invention) is compared to a predefined reference in step 600. In response thereto, in step 700, a short code word to be transmitted in the next measurement cycle, which is successive in time by the first ultrasonic sensor, is selected from a predefined plurality of code words. As long as the cruising speed does not exceed the predefined reference, increased use of, for example, short code words is facilitated in order to improve the reaction time of the system and thus to optimize the warning time.

Claims

1. A method for operating an ultrasound transceiver (20), comprising the steps of:

-sending (100), in a first measurement period, a first signal representative of a first code word by means of a first ultrasonic sensor (1) of a first group (G12) of ultrasonic sensors (1-6);

-sending (200) a second signal by means of a second ultrasonic sensor (2) of the first group (G12);

receiving (300), by means of a third ultrasonic sensor (1, 2), echoes of the first signal and of the second signal reflected by the same surrounding object;

distinguishing (400) the part of the echo from the first signal from the part of the echo from the second signal by means of decoding of the code word,

wherein the second signal has a substantially shorter duration and/or amplitude than the first signal,

wherein the evaluation of the echo from the second signal has ended at a time when the first signal is also evaluated.

2. Method according to claim 1, wherein the ultrasound sensors (1, 2) of the first group (G12) are spatially arranged such that they are arranged suitable for receiving cross-echoes from each other.

3. A method according to claim 1 or 2, wherein the second signal represents a second codeword.

4. The method according to claim 1 or 2, wherein the markings of the first code word each consist of a time signal segment whose temporal behavior can always be differentiated from the second signal by means of matched filtering.

5. The method of claim 4, wherein the method is applied to

A fundamental frequency; and/or

Fundamental frequency curve, in particular with respect to

Start frequency and/or target frequency and/or

A direction of frequency change; and/or

A frequency change speed; and/or

Frequency range

Successive time signal segments are distinguished from one another.

6. The method of claim 1 or 2, further comprising

-transmitting (500), by means of said first ultrasonic sensor (1) of said first group (G12) of ultrasonic sensors (1-6), a third signal representative of a third code word in a second measurement period; and/or

-transmitting (100) a fourth signal representing the first code word by means of a third ultrasonic sensor (4) of a second group (G45), wherein the ultrasonic sensors (1, 2) of the first group (G12) are spatially arranged such that they are not suitable for receiving echoes from signals of the second group (G45).

7. The method of claim 1 or 2, further comprising

The allocation between the used code words and the ultrasonic sensors (1-6) is changed for a subsequent transmission period, wherein the change takes place in particular in accordance with a predefined sequence and/or randomly.

8. The method of claim 1 or 2, further comprising

Comparing (600) the cruising speed of the ultrasound transceiver (20) with a predefined reference and in response thereto

The code word to be transmitted by the first ultrasonic sensor (1) in the next measurement cycle is selected (700) from a predefined plurality of code words, in particular of varying length.

9. An ultrasonic measurement system comprising

A first group (G12) of ultrasonic sensors (1, 2) having:

-a first ultrasonic sensor (1), and

-a second ultrasonic sensor (2) and

a second group (G45) of ultrasonic sensors (4, 5) having:

-a third ultrasonic sensor (4)

Wherein the first group (G12) of ultrasonic sensors (1, 2) are spatially arranged such that they are not suitable for receiving echoes of the second group (G45), wherein the ultrasonic measurement system (20) is provided for carrying out the method according to any one of the preceding claims.

10. A motion mechanism comprising the ultrasonic measurement system (20) of claim 9.