JP2019200194A - Object detection device and parking support device - Google Patents

Abstract

To realize detection of an object existing within a closer range.SOLUTION: According to one example of an embodiment, an object detection device includes: a transmission and reception unit having an oscillator capable of transmitting and receiving an ultrasonic wave to transmit a transmission signal subjected to encoding for giving identification information of a prescribed code length by the oscillator, and to receive the transmission signal reflected by an object existing around as a reception signal; a correlation processing unit for acquiring a first correlation value corresponding to similarity between identification information of the transmission signal and identification information of the reception signal just after the transmission of the transmission signal is completed, and determining whether or not to receive a reception signal to which identification information whose similarity to the identification information of the transmission signal has a prescribed level or more is given on the basis of a comparison result between the first correlation value and a first threshold; and a detection unit for detecting information on the object in the case of determining that the reception signal is received, the reception signal having the identification information whose similarity to the identification information of the transmission signal has the prescribed level or more.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to an object detection device and a parking assistance device.

  Conventionally, a transmission signal as an ultrasonic wave is transmitted by a vibrator such as a piezoelectric element, and a transmission signal reflected by an object is received by a vibrator as a reception signal to obtain a difference in timing of transmission and reception of the ultrasonic waves. Thus, a technique for acquiring information related to an object such as a distance to the object is known.

International Publication WO2016 / 167003

  In the above-described technology using a vibrator, even if transmission of a transmission signal is completed, the vibrator continues to vibrate due to inertia, so it takes time for the vibration of the vibrator to subside. Such time is called reverberation time. Here, when the received signal is received during the reverberation time, the vibration of the vibrator generated by the received signal and the vibration of the vibrator remaining due to inertia are mixed. In this case, for example, it is difficult to accurately detect only the received signal due to a certain threshold value related to amplitude, and conventionally, detection of the received signal has been avoided until the reverberation time ends.

  However, in situations where the object to be detected is very close, such as when the difference between the vehicle width and the parking frame (wall, etc.) is very small, the transmission will occur before the reverberation time ends. It is also possible that the signal will come back. Therefore, there is a need for a technique for detecting a received signal and detecting an object located at a closer distance even before the reverberation time ends.

  Therefore, one of the problems of the present disclosure is to provide an object detection device and a parking assistance device that can realize detection of an object present at a closer distance.

  An object detection device as an example of the present disclosure includes a transducer capable of transmitting and receiving ultrasonic waves, and transmits a transmission signal subjected to encoding that gives identification information of a predetermined code length by the transducer, A transmission / reception unit that receives a transmission signal reflected by an object present in the surroundings as a reception signal, and the first corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal immediately after the transmission of the transmission signal is completed. 1 correlation value is acquired, and based on the comparison result between the first correlation value and the first threshold value, a reception signal to which identification information having a degree of similarity with the identification information of the transmission signal is given is received. If it is determined that a reception signal to which identification information having a degree of similarity between the correlation processing unit for determining whether or not the transmission signal is equal to or higher than a predetermined level has been received, information on the object is A detection unit for detecting That.

  According to the above configuration, whether or not the transmission signal is reflected and received as a reception signal immediately after the transmission of the transmission signal is completed using the identification information given to the transmission signal (and the reception signal). Can be determined. Accordingly, since the received signal can be detected even before the reverberation time ends, it is possible to provide an object detection device that can realize detection of an object present at a closer distance.

  In the above-described object detection device, the correlation processing unit includes at least part of the identification information of the transmission signal from immediately after the transmission of the transmission signal is completed until the reverberation time until the vibration due to the inertia of the vibrator subsides ends. The first correlation value corresponding to the similarity between at least a part of the identification information of the received signal is obtained, and the identification information of the transmission signal is obtained based on the comparison result between the first correlation value and the first threshold value. It is determined whether or not a received signal to which identification information having a similarity level equal to or higher than a predetermined level has been received. According to such a configuration, unlike the case of always considering the information of all the code lengths of the identification information, the time required for obtaining (calculating) the first correlation value can be shortened. Detection can be realized.

  Further, in the above-described object detection device, the correlation processing unit sets the first threshold value to be compared with the first correlation value immediately after the transmission of the transmission signal is completed and after the reverberation time until the vibration due to the inertia of the vibrator subsides ends. The first first threshold value is different from the second first threshold value as a threshold value to be compared with the first correlation value immediately after the transmission signal transmission is completed and before the reverberation time ends. According to such a configuration, appropriate detection of an object can be realized by using different first thresholds depending on the situation.

  In the object detection device described above, the second first threshold value is set so as to decrease with time. According to such a configuration, it is possible to obtain an appropriate second first threshold value that matches a transmission signal (reception signal) that attenuates with time (that is, an increase in propagation distance).

  In the object detection device described above, the correlation processing unit acquires the first correlation value, and then is adjacent to the first pattern corresponding to the temporal change of the first correlation value, the first peak, and the first peak. A second correlation value corresponding to the similarity with at least a part of a second pattern set in advance so as to include a second peak smaller than the first peak is acquired, and the second correlation value and the second threshold value are acquired. On the basis of the comparison result with the transmission signal, it is determined whether a plurality of signals are received as reception signals to which identification information having a similarity level equal to or higher than a predetermined level is received. When it is determined that a plurality of signals are received, information regarding a plurality of objects that respectively cause reflection of the plurality of signals is detected as information regarding the object. According to such a configuration, information relating to reflection in a plurality of modes can be more accurately obtained by two correlation processes of the correlation process for acquiring the first correlation value and the correlation process for acquiring the second correlation value. Can be detected.

  In this case, the correlation processing unit changes the section of the second pattern used for acquiring the second correlation value according to the elapsed time after the transmission of the transmission signal is completed. According to such a configuration, an appropriate second correlation value can be obtained using an appropriate section of the second pattern according to the elapsed time after the transmission of the transmission signal is completed. .

  In this case, the correlation processing unit uses the section on the terminal end side of the second pattern for acquisition of the second correlation value as the elapsed time after the transmission of the transmission signal is completed is shorter. When the elapsed time after the transmission is completed is equal to or longer than the predetermined time, the entire second pattern is used for obtaining the second correlation value. According to such a configuration, the second pattern section used for acquiring the second correlation value is appropriately set according to the relationship between the elapsed time after the transmission of the transmission signal is completed and the predetermined time. Can do.

  Further, in this case, the predetermined time is a reverberation time from immediately after the transmission of the transmission signal is completed until the vibration due to the inertia of the vibrator subsides. According to such a configuration, it is possible to more appropriately set the second pattern section used for acquiring the second correlation value in consideration of the reverberation time.

  In the above-described object detection device, the detection unit calculates a distance to the object as information on the object based on a difference between the timing at which the transmission signal is transmitted and the timing at which the reception signal is received. including. According to such a configuration, the distance to the object can be obtained as a detection result.

  An object detection device as another example of the present disclosure includes a transducer capable of transmitting and receiving ultrasonic waves, and transmits a transmission signal that has been encoded to give identification information of a predetermined code length by the transducer. A transmission / reception unit that receives a transmission signal reflected by an object existing in the surroundings as a reception signal, and a reverberation time until the vibration due to the inertia of the vibrator is stopped after the transmission of the transmission signal is completed A correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal is acquired, and the similarity with the identification information of the transmission signal is predetermined based on a comparison result between the correlation value and the threshold value. Reception provided with identification information having a level of similarity between the correlation processing unit for determining whether or not a reception signal provided with identification information having the above level is received and the identification information of the transmission signal is higher than a predetermined level Determines that a signal has been received If it comprises a detection unit for detecting information about an object, the.

  According to the above configuration, the reverberation time from the completion of the transmission of the transmission signal using the identification information given to the transmission signal (and the reception signal) until the vibration due to the inertia of the vibrator subsides. Until the process ends, it can be determined whether the transmission signal is reflected and received as a reception signal. Accordingly, since the received signal can be detected even before the reverberation time ends, it is possible to provide an object detection device that can realize detection of an object present at a closer distance.

  In addition, an object detection device as still another example of the present disclosure includes a transducer capable of transmitting and receiving ultrasonic waves, and transmission subjected to encoding that gives identification information of a predetermined code length by the transducer. A transmission / reception unit that transmits a signal and receives a transmission signal reflected by an object present in the surroundings as a reception signal, and a degree of similarity between transmission signal identification information and reception signal identification information after transmission signal transmission is completed And a first pattern corresponding to a temporal change of the first correlation value, and a first peak and a second peak smaller than the first peak adjacent to the first peak. As described above, the information on the object is obtained based on the correlation processing unit that acquires the second correlation value corresponding to the similarity with at least a part of the preset second pattern and the comparison result between the second correlation value and the threshold value. A detection unit for detecting

  According to the configuration as described above, the correlation processing for acquiring the first correlation value and the correlation processing for acquiring the second correlation value are executed after the transmission signal transmission is completed. Thus, it is possible to provide an object detection device capable of realizing detection of an object present at a closer distance.

  Further, a parking assist device as still another example of the present disclosure is an object detection device mounted on a vehicle, and includes a vibrator capable of transmitting and receiving ultrasonic waves, and the vibrator has a predetermined code length. A transmission / reception unit that transmits a transmission signal encoded with identification information and receives a transmission signal reflected by a surrounding object as a reception signal, and a transmission signal immediately after transmission of the transmission signal is completed The correlation value corresponding to the similarity between the identification information of the received signal and the identification information of the received signal is acquired, and based on the comparison result between the correlation value and the threshold, it is determined whether the similarity is at a predetermined level or higher. An object detection device comprising: a correlation processing unit; and a detection unit that detects information related to an object when the similarity is determined to be at a predetermined level or higher; and a detection unit of the object detection device mounted on the vehicle. Regarding detected objects Based on the information provided with a parking assist processing unit for executing parking assist vehicle, a.

  According to the above configuration, whether or not the transmission signal is reflected and received as a reception signal immediately after the transmission of the transmission signal is completed using the identification information given to the transmission signal (and the reception signal). Can be determined. Thereby, since the received signal can be detected even before the reverberation time ends, it is possible to provide a parking assistance device that can realize detection of an object present at a closer distance.

  In the parking assistance device described above, the object detection device includes a plurality of object detection devices, and the plurality of object detection devices detect information on the object simultaneously and in parallel using different identification information. According to such a configuration, since the situation around the vehicle can be detected more quickly and in detail based on a plurality of detection results acquired in parallel, the parking can be performed more quickly and more accurately. Support can be realized.

FIG. 1 is an exemplary and schematic view showing an external appearance of a vehicle including an object detection device according to the first embodiment (and the second embodiment) as viewed from above. FIG. 2 is an exemplary and schematic diagram illustrating a configuration of the object detection device according to the first embodiment. FIG. 3 is an exemplary schematic graph showing an example of a waveform of a signal transmitted and received by the object detection device according to the first embodiment. FIG. 4 is an exemplary and schematic flowchart illustrating a series of processing executed by the object detection apparatus according to the first embodiment to detect an object. FIG. 5 is an exemplary and schematic block diagram illustrating a configuration of a parking assistance device including an object detection device according to a modification of the first embodiment. FIG. 6 is an exemplary schematic diagram for explaining the necessity of the second embodiment. FIG. 7 is an exemplary schematic view showing a reference pattern according to the second embodiment. FIG. 8 is an exemplary schematic view showing the result of the secondary correlation processing according to the second embodiment. FIG. 9 is an exemplary and schematic flowchart illustrating a series of processing executed by the object detection device according to the second embodiment to detect an object.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The configuration of the embodiment described below, and the operation and result (effect) brought about by the configuration are merely examples, and are not limited to the following description.

<First Embodiment>
FIG. 1 is an exemplary and schematic diagram showing an external view of a vehicle 1 including object detection devices 101 to 104 according to a first embodiment (and a second embodiment to be described later). Although details will be described later, the object detection apparatuses 101 to 104 perform transmission / reception of ultrasonic waves and acquire a time difference of the transmission / reception, thereby obtaining an object including a human being present (for example, the obstacle X1 shown in FIG. 2). ) Is a sensing device that detects information related to.

  As shown in FIG. 1, the object detection devices 101 to 104 are mounted on a vehicle body 2 of a four-wheel vehicle 1 including a pair of left and right front wheels 3F and a pair of left and right rear wheels 3R. More specifically, the object detection devices 101 to 104 are installed at different positions on the rear end of the vehicle body 2 such as a rear bumper.

  In the first embodiment, the hardware configurations and functions of the object detection devices 101 to 104 are the same. Therefore, hereinafter, for the sake of simplicity, the object detection devices 101 to 104 may be collectively referred to as the object detection device 100.

  FIG. 2 is an exemplary and schematic diagram illustrating a configuration of the object detection device 100 according to the first embodiment. As shown in FIG. 2, the transmitter / receiver 110 and the controller 120 are included.

  The transmission / reception unit 110 includes a transducer 111. The transducer 111 includes a vibrator 111a such as a piezoelectric element, and realizes transmission / reception of ultrasonic waves by the vibrator 111a.

  More specifically, the transducer 111 transmits an ultrasonic wave generated according to the vibration of the vibrator 111a as a transmission signal, and the ultrasonic wave transmitted as the transmission signal is reflected by an object existing outside and returned. The vibration of the vibrator 111a brought about by coming is received as a reception signal. In FIG. 2, an obstacle X1 installed on the road surface X2 is illustrated as an object that reflects ultrasonic waves from the transducer 111.

  Here, in the above-described technique using the vibrator 111a, even if the transmission of the transmission signal is completed, the vibrator 111a continues to vibrate due to inertia. Reverberation time). Here, when the received signal is received during the reverberation time, the vibration of the vibrator 111a generated by the received signal and the vibration of the vibrator 111a remaining due to inertia are mixed. In this case, for example, it is difficult to accurately detect only the received signal due to a certain threshold value related to amplitude, and conventionally, detection of the received signal has been avoided until the reverberation time ends.

  However, in situations where the object to be detected is very close, such as when the difference between the vehicle width and the parking frame (wall, etc.) is very small, the transmission will occur before the reverberation time ends. It is also possible that the signal will come back. Therefore, there is a need for a technique for detecting a received signal and detecting an object located at a closer distance even before the reverberation time ends.

  Therefore, in the first embodiment, the following hardware and functions are provided to the transmission / reception unit 110 and the control unit 120, thereby realizing detection of an object that is present at a closer distance.

  In the first embodiment, the transmission / reception unit 110 includes an oscillator 112, a modulator 113, and a demodulator 114 in addition to the transducer 111 described above. These configurations are realized in hardware by an analog circuit, for example.

  The oscillator 112 oscillates a signal having a predetermined frequency for vibrating the vibrator 111 a of the transducer 111 and outputs the oscillated signal to the modulator 113.

  The modulator 113 modulates the signal input from the oscillator 112 based on the signal input from the control unit 120, and outputs the modulated signal to the transmitter / receiver 111 as a voltage signal for vibrating the vibrator 111a. . In the first embodiment, the modulation method may be a single or combination of generally known methods such as an amplitude modulation method, a phase modulation method, and a frequency modulation method. In the first embodiment, the modulator 113 may be configured to appropriately switch a plurality of modulation schemes based on an instruction from the control unit 120.

  Demodulator 114 demodulates the signal input from transducer 111 and outputs the demodulated signal to control unit 120. As the modulation method, a method corresponding to the modulation method used by the modulator 113 is used.

  The control unit 120 includes a storage unit 121, an encoding processing unit 122, a correlation processing unit 123, and a distance measuring unit 124. For example, when the control unit 120 is configured as a processing device having hardware similar to that of a normal computer such as a processor or a memory, the processor 120 reads out and executes a program stored in the memory. It is realized functionally (that is, through cooperation between hardware and software). In the first embodiment, each unit constituting the control unit 120 may be realized in hardware by a dedicated analog circuit or the like.

  The storage unit 121 stores various data used by the control unit 120 to realize its functions.

  The encoding processing unit 122 performs encoding that adds identification information of a predetermined code length to the transmission signal, using modulation by the modulator 113. More specifically, the encoding processing unit 122 generates a bit string composed of a series of 0 or 1 bits as identification information unique to the object detection apparatus 100. The length of this bit string corresponds to the code length of the identification information given to the transmission signal. The encoding processing unit 122 outputs the generated bit string to the modulator 113 and causes the modulator 113 to perform modulation according to each bit of the bit string, thereby adding identification information corresponding to the bit string to the transmission signal. Encoding is realized.

  For example, when the amplitude modulation method is used as the modulation method, the modulator 113 receives and transmits a bit string as identification information from the encoding processing unit 122 according to whether each bit of the bit string is 0 or 1. The amplitude of the voltage signal output to the wave device 111 is changed. Similarly, when the phase modulation scheme is used as the modulation scheme, the modulator 113 outputs a voltage signal output to the transducer 111 according to whether each bit of the bit string input from the encoding processing unit 122 is 0 or 1 When the frequency modulation method is used as the modulation method, the frequency of the voltage signal output to the transmitter / receiver 111 according to whether each bit of the bit string input from the encoding processor 122 is 0 or 1 To change.

  The correlation processing unit 123 acquires a correlation value corresponding to the degree of similarity (matching degree) between the identification information of the transmission signal and the identification information of the reception signal, and based on the comparison result between the correlation value and the threshold value (first threshold value). Thus, it is determined whether or not the similarity is at a predetermined level or higher. The correlation value reaches a peak exceeding the threshold when the waveforms of the transmission signal and the reception signal match. Such a correlation value can be acquired (calculated) based on, for example, a generally well-known correlation function. The correlation processing unit 123 uses the correlation value acquired based on the correlation function or the like, and the bit string generated by the encoding processing unit 122 as identification information given to the transmission signal and demodulated by the demodulator 114 It is determined whether or not the bit string as identification information identified from the received signal is similar (matched) at a predetermined level or higher. Based on the determination result, the received signal demodulated by the demodulator 114 is detected by the object. It is determined whether or not the transmission signal is reflected and returned.

  The distance measuring unit 124 is a detection unit that detects information related to an object (for example, the presence or absence of an object, a distance to the object, and the like) when the similarity is determined to be at a predetermined level or higher. More specifically, the distance measurement unit 124 includes a timing at which a transmission signal is transmitted (more specifically, started to be transmitted), and a timing at which a reception signal is received (more specifically, at which reception has started). The distance to the object is calculated as information on the object by the so-called TOF (Time Of Flight) method based on the difference between the two.

  Here, in the first embodiment, as described above, the identification information is given to the transmission signal, and the demodulator 114 uses the correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal. It is determined whether or not the demodulated reception signal is a transmission signal that has been reflected back by an object. Since the identification information is basically not lost by reflection, based on the identification information, even when the reception signal is received during the reverberation time, due to the vibration of the vibrator 111a generated by the reception signal and the inertia Only the former can be detected from the vibration of the remaining vibrator 111a.

  Therefore, in the first embodiment, the correlation processing unit 123 acquires the correlation value immediately after the transmission of the transmission signal is completed, and based on the comparison result between the correlation value and the threshold (first threshold), the transmission signal It is determined whether or not the similarity between the identification information of the received signal and the identification information of the received signal is at a predetermined level or higher.

  FIG. 3 is an exemplary and schematic graph showing an example of a waveform of a signal transmitted and received by the object detection apparatus 100 according to the first embodiment. In the graph shown in FIG. 3, the horizontal axis corresponds to time, and the vertical axis corresponds to the signal level (for example, amplitude) of the signal transmitted and received by the object detection apparatus 100 via the transducer 111 (vibrator 111a). To do.

  In the graph shown in FIG. 3, a solid line L11 represents an example of an envelope that represents a signal level of a signal transmitted and received by the object detection apparatus 100, that is, an temporal change in the degree of vibration of the vibrator 111a. From this solid line L11, the vibrator 111a is driven and oscillated for a time T1 from the timing t0, so that transmission of the transmission signal is completed at the timing t1, and then during the time T2 until the timing t2, the inertial force is applied. It can be read that the vibration of the vibrator 111a continues while being attenuated. Therefore, in the graph shown in FIG. 3, time T2 corresponds to so-called reverberation time.

  A solid line L11 indicates that the degree of vibration of the vibrator 111a has exceeded a predetermined threshold value Th1 represented by a one-dot chain line L21 at a timing t4 when the time Tp has elapsed from the timing t0 when transmission of the transmission signal is started (or more than ) Peak. This threshold value Th1 is an example of a first threshold value, and reception of a reception signal as a transmission signal returned by the vibration of the vibrator 111a being reflected by an object to be detected (for example, the obstacle X1 shown in FIG. 2). Or caused by reception of a received signal as a transmitted signal that is reflected back by an object that is not the subject of the specimen (eg, road surface X2 shown in FIG. 2) It is a value set in advance for the purpose. FIG. 3 shows an example in which the threshold Th1 is set as a constant value that does not change regardless of the passage of time. In the first embodiment, the threshold Th1 is set as a value that changes over time. May be.

  For example, it is possible to determine that a vibration having a peak exceeding (or more than) the threshold value Th1 is caused by reception of a reception signal as a transmission signal reflected and returned by an object to be detected. It can be determined that the vibration having a peak equal to or less than (or less than) the threshold value Th1 is caused by reception of a reception signal as a transmission signal reflected and returned by an object not to be detected. Therefore, it can be read from the solid line L11 that the vibration of the vibrator 111a at the timing t4 is caused by the reception of the reception signal as the transmission signal reflected and returned by the object to be detected.

  In the solid line L11, the vibration of the vibrator 111a is attenuated after the timing t4. Therefore, the timing t4 is the timing at which reception of the reception signal as the transmission signal reflected and returned by the object to be detected is completed, in other words, the transmission signal last transmitted at timing t1 returns as the reception signal. Corresponding to the timing. In the solid line L11, the timing t3 as the peak start point at the timing t4 is the timing at which reception of the reception signal as the transmission signal reflected and returned by the object to be detected starts, in other words, at timing t0. This corresponds to the timing at which the transmission signal transmitted first returns as the reception signal. Therefore, in the solid line L11, the time ΔT between the timing t3 and the timing t4 is equal to the time T1 as the transmission time of the transmission signal.

  Here, in order to obtain the distance to the object to be detected by the TOF method, the time Tf between the timing t0 when the transmission signal starts to be transmitted and the timing t3 when the reception signal starts to be received is obtained. Necessary. This time Tf is obtained by subtracting a time ΔT equal to the time T1 as the transmission time of the transmission signal from the time Tp as the difference between the timing t0 and the timing t4 when the signal level of the reception signal reaches the peak Th1. Can be obtained. The timing t0 can be easily specified as the timing at which the object detection apparatus 100 starts operating, and the time T1 is determined in advance by setting or the like, so that the distance to the object to be detected is determined by the TOF method. It is important to specify the timing t4.

  Therefore, in the first embodiment, as described above, the transmission signal is subjected to predetermined encoding so that identification information having a predetermined code length is given to the transmission signal and the reception signal. In the first embodiment, the correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal is acquired, and the similarity is determined based on the comparison result between the correlation value and the first threshold value. It is determined whether the level is higher than a predetermined level. Note that the first threshold value to be compared with the correlation value is a value corresponding to the threshold value Th1. According to such a configuration, the timing at which the degree of similarity is determined to be a predetermined level or higher can be specified as the timing t4 when the received signal reaches a peak exceeding the threshold Th1, so that the detection target can be detected by the TOF method. The distance to the object can be obtained.

  Now, consider a case where a transmission signal returns as a reception signal before the end of the reverberation time because an object to be detected exists at a short distance. In this case, in the graph shown in FIG. 3, a waveform represented by an envelope like a broken line L12 appears at time T2 (reverberation time) between timing t1 and timing t2.

  Since the transmission signal that returns during the reverberation time propagates only for a short distance, the degree of attenuation is small. Therefore, the vibration (see the broken line L12) is larger than the vibration that remains in the vibrator 111a due to inertia (see the solid line L11). ). Therefore, in the first embodiment, even after the timing t1 at which the transmission of the transmission signal is completed until the timing t2 at which the reverberation time ends, transmission is performed by the object to be detected by the same method as that after the timing t2 described above. It is possible to determine whether the signal is reflected and returned as a received signal.

  However, the signal level of the received signal to be detected immediately after timing t1 to timing t2 is different from the reception level of the received signal to be detected after timing t2. Therefore, the threshold Th2 (see the two-dot chain line L22) as an example of the first first threshold used between immediately after the timing t1 and the timing t2, and the second first threshold used as a reference after the timing t2. As an example, the threshold value Th1 (see the alternate long and short dash line L21) needs to be switched according to time.

  Since the transmission signal attenuates as the propagation distance increases, the signal level of the reception signal decreases as the timing at which the transmission signal returns as the reception signal is delayed. Therefore, in the first embodiment, in order to accurately detect a received signal whose signal level decreases with time, the threshold value Th2 is set to decrease with time. FIG. 3 shows an example in which the one-dot chain line L21 representing the threshold value Th1 and the two-dot chain line L22 representing the threshold value Th2 are continuous at the timing t2 when the reverberation time ends. In the embodiment, the threshold value Th1 and the threshold value Th2 may not be set continuously.

  Thus, in the first embodiment, not only after the reverberation time ends, but also immediately after the transmission signal transmission is completed and until the reverberation time ends, the identification information of the transmission signal and the reception signal are identified. A correlation value corresponding to the degree of similarity with the information is acquired, and it is determined whether or not the degree of similarity is a predetermined level or more based on a comparison result between the correlation value and the threshold value.

  However, in the first embodiment, a correlation value between the first first threshold value as a threshold value to be compared with the correlation value after the reverberation time ends and the time after the reverberation time ends after the transmission of the transmission signal is completed. And a second first threshold value as a threshold value to be compared with each other. The first first threshold value is a value corresponding to the threshold value Th1. The second first threshold value is a value corresponding to the above-described threshold value Th2, and is set so as to decrease with time. In the first embodiment, it is assumed that the object detection apparatus 100 (for example, the correlation processing unit 123) performs the switching between the first first threshold value and the second first threshold value. In this case, both the first first threshold value and the second first threshold value are stored in the storage unit 121.

  Note that if determination of similarity is performed based on all identification information, that is, the entire bit string as identification information, the reliability of the determination result is high, but the calculation may take time, for example, reverberation time is short. In some cases, it may be desirable not to perform similarity determination based on all identification information. Therefore, according to the first embodiment, at least from immediately after the transmission of the transmission signal is completed until the reverberation time ends, a part of the identification information, for example, several bits located at the head of the bit string as the identification information. The degree of similarity may be determined based only on the above. That is, according to the first embodiment, at least a part of the identification information of the transmission signal and the reception signal from immediately after the transmission of the transmission signal is completed until the reverberation time until the vibration due to the inertia of the vibrator 111a ends. A correlation value corresponding to the degree of similarity with at least a part of the identification information is obtained, and the degree of similarity is at a predetermined level or higher based on a comparison result between the correlation value and the threshold (second first threshold). It may be determined whether or not there is.

  FIG. 4 is an exemplary and schematic flowchart illustrating a series of processing executed by the object detection apparatus 100 according to the first embodiment to detect an object.

  In the processing flow shown in FIG. 4, first, in S401, the object detection apparatus 100 (for example, the encoding processing unit 122, the transducer 111, the oscillator 112, and the modulator 113) uses the encoded signal as a transmission signal. Send.

  In step S402, the object detection apparatus 100 (for example, the control unit 120) determines whether or not a predetermined time set as the transmission time of the transmission signal has elapsed.

  If it is determined in S402 that the predetermined time has not yet elapsed, the process returns to S401. On the other hand, if it is determined in S402 that the predetermined time has elapsed, the process proceeds to S403.

  In S403, the object detection device 100 (for example, the correlation processing unit 123) acquires a correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal. That is, the object detection apparatus 100 acquires the correlation value immediately after the transmission of the transmission signal is completed.

  In step S404, the object detection apparatus 100 (for example, the correlation processing unit 123) determines whether or not the reverberation time has ended. This determination may be performed based on a reverberation time set in advance according to the specifications of the vibrator 111a, or the actual vibration of the vibrator 111a is monitored to detect whether the vibration has subsided. May be implemented.

  If it is determined in S404 that the reverberation time has ended, the process proceeds to S405. In step S405, the object detection apparatus 100 (for example, the correlation processing unit 123) determines whether or not the correlation value acquired in step S403 is equal to or greater than the first first threshold set as a correlation value comparison target after the end of the reverberation time. Determine whether.

  If it is determined in S405 that the correlation value is less than the first first threshold, the identification information of the transmission signal and the identification information of the reception signal are not similar (match) at a predetermined level or higher, that is, the transmission signal Can be determined as having not yet returned as a received signal due to reflection. Therefore, in this case, the process returns to S403, and the correlation value is acquired again.

  On the other hand, if it is determined in S404 that the reverberation time has not yet ended, the process proceeds to S406. In S <b> 406, the object detection apparatus 100 (for example, the correlation processing unit 123) determines whether or not the correlation value acquired in S <b> 403 is equal to or greater than the second first threshold set as a correlation value comparison target during the reverberation time. to decide.

  If it is determined in S406 that the correlation value is less than the second first threshold, the identification information of the transmission signal and the identification information of the reception signal are not similar (match) at a predetermined level or higher, that is, the transmission signal Can be determined as having not yet returned as a received signal due to reflection. Therefore, in this case, the process returns to S403, and the correlation value is acquired again.

  Here, in the case where it is determined in S405 that the correlation value is greater than or equal to the first first threshold value, and in the case where it is determined that the correlation value is greater than or equal to the second first threshold value in S406, the transmission signal It can be determined that the identification information of the received signal and the identification information of the received signal are similar (matched) at a predetermined level or higher, that is, the transmitted signal is returned as the received signal by reflection. Therefore, in this case, the process proceeds to the next S407.

  In step S407, the object detection apparatus 100 (for example, the distance measurement unit 124) receives the timing at which the transmission signal is transmitted (more specifically, when transmission is started) and the reception signal as the transmission signal returned by reflection. The distance to the object that reflected the transmission signal is acquired (calculated) by the TOF method based on the difference from the timing (more specifically, reception is started). Then, the process ends.

  As described above, the object detection apparatus 100 according to the first embodiment includes the transmission / reception unit 110, the correlation processing unit 123, and the distance measurement unit 124 configured as follows. The transmission / reception unit 110 includes a transducer 111a capable of transmitting and receiving ultrasonic waves. The transducer 111a transmits a transmission signal that has been encoded to give identification information of a predetermined code length, and is reflected by an object. The received transmission signal is received as a reception signal. The correlation processing unit 123 acquires a correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal immediately after the transmission of the transmission signal is completed. Based on the comparison result with the first first threshold value or the second first threshold value), it is determined whether or not the similarity is at a predetermined level or higher corresponding to the threshold value. The distance measuring unit 124 detects information related to an object (distance to the object) when the similarity is determined to be at a predetermined level or higher.

  According to the above configuration, whether or not the transmission signal is reflected and received as a reception signal immediately after the transmission of the transmission signal is completed using the identification information given to the transmission signal (and the reception signal). Can be determined. As a result, the received signal can be detected even before the reverberation time ends, so that it is possible to realize detection of an object present at a closer distance.

  Furthermore, the above configuration is effective when a plurality of object detection devices 100 are provided. For example, in a configuration in which a plurality of object detection devices 101 to 104 as shown in FIG. 1 are provided, if the identification information of the object detection devices 101 to 104 is different, a certain object detection device 100 transmits. When the transmission signal returns as a reception signal, it is possible to avoid erroneous detection of the reception signal by another object detection device 100. That is, in the first embodiment, the object detection apparatuses 101 to 104 can detect information on an object simultaneously and in parallel by using different identification information. According to such a configuration, the situation around the vehicle 1 can be detected more quickly and in detail based on a plurality of detection results acquired in parallel, so that it is quicker and more accurate. Parking assistance can be realized.

<Modification>
In the above description, the technique of the first embodiment is applied to a configuration that detects information about an object by transmitting and receiving ultrasonic waves, but the technique of the first embodiment is a wave other than ultrasonic waves. The present invention can also be applied to a configuration in which information about an object is detected by transmission / reception of sound waves, millimeter waves, electromagnetic waves, or the like.

  Further, in the first embodiment described above, the object detection apparatus 100 itself controls operations such as switching of the transmission signal modulation method and switching between the first first threshold value and the second first threshold value. Illustrated. However, these operations may be realized under the control from the outside, as in the modification described below.

  FIG. 5 is an exemplary schematic block diagram illustrating a configuration of a parking assistance device 500 including the object detection device 100a according to the modification of the first embodiment. As shown in FIG. 5, the parking assistance device 500 includes an object detection device 100 a and a parking assistance ECU (Electronic Control Unit) 501.

  The object detection device 100a is a sensing device that detects information related to an object existing in the vicinity, similar to the object detection device 100 according to the first embodiment described above. The parking assistance ECU 501 is a microcomputer as a parking assistance control unit that realizes parking assistance (including automatic parking). The object detection apparatus 100a and the parking assistance ECU 501 are connected via a communication path 550 using a LIN (Local Interconnect Network), a UART (Universal Asynchronous Receiver / Transmitter), or the like.

  In the modification, the basic hardware configuration and functions of the transmission / reception unit 110a and the control unit 120a included in the object detection device 100a are substantially the same as those in the first embodiment described above. However, in the modification, the operations performed in the object detection device 100a, such as switching of the transmission signal modulation method and switching between the first first threshold value and the second first threshold value, are controlled by the parking assist ECU 501. This is different from the first embodiment described above in that it is realized under the above. According to such a configuration, the function of the object detection device 100a can be simplified.

Second Embodiment
In the first embodiment described above, information about an object is detected based on a correlation value (peak) obtained as a result of one correlation process. However, for example, as shown in FIG. 6 below, it may be difficult to accurately detect information on an object simply by considering a correlation value obtained as a result of one correlation process.

  FIG. 6 is an exemplary schematic diagram for explaining the necessity of the second embodiment. In the example shown in FIG. 6, a solid line L610 indicates a time-varying pattern of correlation values based on a transmission signal returned at a strong level in accordance with, for example, reflection from a hard object or reflection from an object at a short distance. A broken line L620 represents an envelope representing a temporal change pattern of a correlation value based on a transmission signal returned at a weak level in accordance with, for example, reflection from a soft object or reflection from an object at a long distance. Is a line.

  In general, an envelope representing a temporal change pattern of a correlation value may have a first peak called a main lobe and a second peak smaller than the first peak adjacent to the first peak called a side lobe. Are known. Accordingly, in the example shown in FIG. 6, the solid line L610 includes the first peak P611 and the second peaks P612 and P613 on both sides of the first peak P611, and the broken line L620 includes the first peak P621. And second peaks P622 and P623 on both sides of the first peak P621.

  In the example shown in FIG. 6, for simplicity, one side lobe exists on both sides of the main lobe, and the level (size) of these two side lobes is substantially the same. In practice, there may be more than one sidelobe, and the level of each sidelobe may vary.

  Further, in the example shown in FIG. 6, for convenience of explanation, the temporal change pattern of two types of correlation values corresponding to reflection in two different modes is represented by a solid line L610 corresponding to the reflection in the first mode. And a broken line L620 corresponding to the reflection in the second mode. However, normally, since the reflection mode cannot be distinguished in advance, the pattern of temporal change of the correlation value actually obtained in the correlation processing is a pattern in which the solid line L610 and the broken line L620 are combined.

  Here, in the correlation value obtained by the technique of the first embodiment described above, it is a first peak called a main lobe that can be compared with a threshold value (first threshold value). However, in the example shown in FIG. 6, the first peak P621 of the broken line L620 corresponding to the reflection in the second mode is in time series with the second peak P613 of the solid line L610 corresponding to the reflection in the first mode. Since they partially overlap as seen, it is difficult to accurately extract only the first peak P621 of the broken line L620 from the combined pattern. That is, from the example shown in FIG. 6, it is difficult to accurately detect information regarding an object that causes reflection in the second mode.

  Therefore, the object detection apparatus 1100 (see FIG. 2) according to the second embodiment is based on the configuration and processing described below, and a plurality of (for example, two types) such as the example shown in FIG. Even in situations where multiple temporal changes (for example, two types) of correlation values in response to reflections in different modes appear in a partially overlapping form, more information about each object that causes reflection in each mode Realize accurate detection.

  The configuration of the object detection device 1100 according to the second embodiment is substantially the same as the configuration of the object detection device 100 according to the first embodiment (see FIG. 2) described above. However, in the second embodiment, the functions of the correlation processing unit 1123 and the distance measuring unit 1124 of the control unit 1200 are different from those of the first embodiment described above.

  More specifically, in the second embodiment, the correlation processing unit 1123 first corresponds to the similarity between the identification information of the transmission signal and the identification information of the reception signal by the same correlation processing as in the first embodiment described above. A first correlation value is acquired. For example, in the example shown in FIG. 6, the pattern in which the solid line L610 and the broken line L620 are combined corresponds to the time change of the first correlation value. In the following description, the first correlation value may be referred to as a primary correlation value, and the correlation process for obtaining the primary correlation value may be referred to as a primary correlation process. The primary correlation process can be acquired based on a generally well-known correlation function or the like.

  And in 2nd Embodiment, the correlation process part 1123 is the similarity of the 1st pattern corresponding to the time change of said 1st correlation value, and at least one part of the reference | standard pattern as a preset 2nd pattern. A second correlation value corresponding to is obtained. The reference pattern is information as shown in FIG. 7, which is acquired by estimating in advance the relationship between the main lobe and the side lobe in the temporal change of the primary correlation value by calculation or the like. Hereinafter, the second correlation value may be referred to as a secondary correlation value, and the correlation processing for obtaining the secondary correlation value may be referred to as a secondary correlation processing. The secondary correlation process can also be acquired based on a generally well-known correlation function or the like, similar to the above-described primary correlation process.

  FIG. 7 is an exemplary schematic diagram illustrating an example of a reference pattern according to the second embodiment. In the example shown in FIG. 7, the solid line L700 corresponds to the reference pattern.

  As shown in FIG. 7, the reference pattern shown by the solid line L700 is similar to the patterns of the solid line L610 and the broken line L620 shown in FIG. 6, and is adjacent to the first peak P701 and the first peak P701. And a second peak P702 that is smaller than the first peak P701.

  Therefore, if (secondary) correlation processing is performed on the reference pattern indicated by the solid line L700 and the pattern obtained by combining the solid line L610 and the broken line L620 shown in FIG. 6, based on the similarity between the two, Information relating to the pattern indicated by the solid line L610 and information relating to the pattern indicated by the broken line L620 can be acquired in a form separated from the pattern obtained by combining the solid line L610 and the broken line L620 at a certain level. That is, according to the secondary correlation processing, the information on the reflection in a plurality of modes is mixed from information mixed in a state indistinguishable from each other (the above-mentioned primary correlation value), as shown in FIG. Information separated at a certain level for each aspect can be acquired.

  FIG. 8 is an exemplary schematic view showing the result of the secondary correlation processing according to the second embodiment. In the example shown in FIG. 8, the solid line L801 is a temporal change pattern of the secondary correlation value that appears as a result of the secondary correlation processing for the solid line L610 shown in FIG. 6 and the solid line L700 shown in FIG. 7. Correspondingly, a broken line L802 corresponds to a temporal change pattern of the secondary correlation value that appears as a result of the secondary correlation processing for the broken line L620 shown in FIG. 6 and the solid line L700 shown in FIG.

  In the example shown in FIG. 8, for convenience of explanation, the temporal change pattern of the secondary correlation value is illustrated by being divided into a solid line L801 and a broken line L802. However, similarly to the relationship between the solid line L610 and the broken line L602 shown in FIG. 6, the temporal change pattern of the secondary correlation value actually obtained in the secondary correlation process is a pattern in which the solid line L801 and the broken line L802 are combined. .

  However, the temporal change pattern of the secondary correlation value actually obtained in the secondary correlation processing is in a form separated into a plurality of (for example, two) patterns having peaks at different positions in time series at a certain level. . For example, in the example shown in FIG. 8, the temporal change pattern of the secondary correlation value is separated into a pattern indicated by a solid line L801 and a pattern indicated by a broken line L802 at a certain level.

  Here, the pattern indicated by the solid line L801 is a pattern that appears because the solid line L610 shown in FIG. 6 is similar to the solid line L700 shown in FIG. 7, and the pattern shown by the broken line L802 is This is a pattern that appears because the broken line L620 shown in FIG. 6 is similar to the solid line L700 shown in FIG. Since the pattern indicated by the solid line L801 and the pattern indicated by the broken line L802 reach peaks at different positions in time series, reflections in two different modes are detected from the secondary correlation values shown in FIG. Is possible.

  As described above, according to the secondary correlation processing, information related to reflection in a plurality of modes can be acquired in a form separated at a certain level for each mode of reflection. Therefore, if an appropriate threshold value Th800 is set and the threshold value Th800 is compared with the secondary correlation value, information regarding reflection in each aspect can be appropriately detected collectively. The threshold value Th800 is an example of a “second threshold value”.

  For example, in the example shown in FIG. 8, two patterns, a pattern indicated by a solid line L801 and a pattern indicated by a broken line L802, can be detected as patterns having a peak having a level equal to or higher than the threshold Th800. Therefore, according to the example shown in FIG. 8, it can be detected that the transmission signal is reflected in two different modes and returned as two different received signals.

  Then, considering the timing at which the transmission signal is transmitted and the timing at which the two different types of received signals are received, information on each of the objects that cause reflection in the two types of modes is detected. be able to. That is, if the difference between the timing at which the transmission signal is transmitted and the timing at which the first reception signal is received is taken into account, the distance to the object that causes reflection in the first mode can be detected. Considering the difference between the timing at which the transmission signal is transmitted and the timing at which the second received signal is received, the distance to the object that causes reflection in the second mode can be detected.

  Thus, according to the second embodiment, even in a situation where the temporal changes of a plurality of primary correlation values corresponding to reflections in a plurality of different modes appear in a partially overlapping form, the secondary correlation Based on the value, it is possible to more accurately detect information regarding each object that causes reflection in each aspect.

  That is, in the second embodiment, after acquiring the primary correlation value, the correlation processing unit 1123 obtains at least one of the first pattern corresponding to the temporal change of the primary correlation value and the second pattern preset as the reference pattern. A secondary correlation value corresponding to the degree of similarity is obtained. Then, the distance measurement unit 1124 detects information related to the object (distance to the object) based on the comparison result between the secondary correlation value and the second threshold value.

  More specifically, the correlation processing unit 1123 acquires the primary correlation value, then acquires the secondary correlation value, and based on the comparison result between the second correlation value and the second threshold, It is determined whether or not a plurality of signals are received as received signals to which identification information having a similarity level of a predetermined level or higher is given. Then, when it is determined that a plurality of signals have been received, the distance measuring unit 1124 uses, as information on the object, information on the plurality of objects that respectively cause reflection of the plurality of signals (distances to the plurality of objects). Detect.

  Incidentally, as described above, when attention is paid to the vibrator 111a immediately after the transmission of the transmission signal is completed (for example, immediately after the timing t1 in FIG. 3) until the reverberation time elapses, the vibration remaining in inertia (see the solid line L11). ) (See the broken line L12) is easy to detect, but vibrations smaller than the vibration remaining in inertia (see the solid line L11) are difficult to detect. Therefore, in the reverberation time, it is not always possible to accurately detect all temporal changes in the signal level of the received signal. Therefore, the primary correlation value in the reverberation time is normal for all main lobes and side lobes (ie, the reference pattern). It is not necessarily in the same manner as the whole.

  Therefore, in the second embodiment, the correlation processing unit 1123 changes the interval of the reference pattern used for acquiring the secondary correlation value according to the elapsed time after the transmission of the transmission signal is completed. For example, if the elapsed time from the completion of transmission of the transmission signal is equal to or greater than the reverberation time, all the changes in the signal level of the received signal can be detected, so the primary correlation value is similar to the entire reference pattern. Expect to show a pattern. On the other hand, if the elapsed time from the completion of transmission of the transmission signal is less than the reverberation time, only the end-side part after the reverberation time can be detected from the time change of the signal level of the received signal. It is expected that the correlation value shows a pattern similar to only the terminal portion in the time series in the reference pattern. Therefore, in the second embodiment, as shown in FIG. 7, in the former case, the correlation processing unit 1123 uses the entire section W700 of the reference pattern indicated by the solid line L700 for acquiring the secondary correlation value, and the latter. In this case, a part of the end side section W701 of the reference pattern indicated by the solid line L700 is used to obtain the secondary correlation value.

  That is, in the second embodiment, the correlation processing unit 1123 uses the section on the terminal end side of the reference pattern for acquisition of the secondary correlation value as the elapsed time after the transmission of the transmission signal is completed is shorter. When the time is equal to or longer than the predetermined time, the entire reference pattern is used for obtaining the secondary correlation value. Note that the predetermined time can be set, for example, to coincide with the reverberation time from immediately after the transmission of the transmission signal is completed until the vibration due to the inertia of the vibrator 111a subsides. With this setting, it is possible to acquire an appropriate secondary correlation value using an appropriate reference pattern according to the elapsed time after the transmission of the transmission signal is completed.

  FIG. 9 is an exemplary and schematic flowchart illustrating a series of processes executed by the object detection device 1100 according to the second embodiment to detect an object.

  In the processing flow shown in FIG. 9, first, in S901, the object detection device 1100 (for example, the transducer 111) transmits a transmission signal. This transmission signal is encoded so as to include identification information having a predetermined code length, as in the first embodiment.

  In step S902, the object detection device 1100 (for example, the transducer 111) receives the reception signal. Since this reception signal is a transmission signal that has been reflected and returned by the object, it should be encoded so as to include identification information of a predetermined code length, like the transmission signal.

  In step S903, the object detection device 1100 (for example, the correlation processing unit 1123) performs the primary correlation corresponding to the similarity between the identification information of the transmission signal transmitted in step S901 and the identification information of the reception signal received in step S902. Get the value.

  In step S904, the object detection device 1100 (for example, the correlation processing unit 1123) causes the secondary correlation corresponding to the similarity between the temporal change pattern of the primary correlation value acquired in step S903 and the preset reference pattern. Get the value.

  In step S905, the object detection apparatus 1100 (for example, the correlation processing unit 1123) executes threshold processing that compares the secondary correlation value acquired in step S904 with the predetermined second threshold described above. In this threshold value processing, based on the comparison result between the secondary correlation value and the second threshold value, information relating to reflection in a plurality of aspects, more specifically, the degree of similarity with the identification information of the transmission signal is greater than or equal to a predetermined value. It is determined whether or not a plurality of signals are received as reception signals to which identification information that is level is assigned.

  In step S906, the object detection device 1100 (for example, the distance measuring unit 1124) acquires the distance to the object based on the result of the threshold processing in step S905. More specifically, when the object detection apparatus 1100 determines that a plurality of signals have been received in the threshold processing in S905, the object detection apparatus 1100 includes information regarding a plurality of objects that respectively cause reflection of the plurality of signals as information regarding the object ( The distance to each of a plurality of objects is acquired. Then, the process ends.

  As described above, the object detection apparatus 1100 according to the second embodiment includes the correlation processing unit 1123 and the distance measuring unit 1124. The correlation processing unit 1123 acquires a primary correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal after the transmission of the transmission signal is completed, and corresponds to the temporal change of the primary correlation value. The similarity between the first pattern and at least part of the reference pattern as the second pattern set in advance so as to include the first peak and the second peak smaller than the first peak adjacent to the first peak. Get the corresponding secondary correlation value. The ranging unit 1124 detects information related to the object (distance to the object) based on the comparison result between the secondary correlation value and the second threshold value.

  More specifically, in the second embodiment, the correlation processing unit 1123 obtains the primary correlation value, and then the first pattern (see FIG. 6) corresponding to the temporal change of the primary correlation value and the preset first pattern. A secondary correlation value (see FIG. 8) corresponding to the similarity between at least a part of the two reference patterns (see FIG. 7) is acquired, and the comparison result between the secondary correlation value and the second threshold value is obtained. Based on this, it is determined whether or not a plurality of signals have been received as reception signals to which identification information having a similarity level equal to or higher than a predetermined level is obtained. Then, when it is determined that a plurality of signals have been received, the distance measuring unit 1124 uses, as information on the object, information on the plurality of objects that respectively cause reflection of the plurality of signals (distances to the plurality of objects). Detect.

  According to the configuration as described above, the correlation processing for acquiring the first correlation value and the correlation processing for acquiring the second correlation value are executed after the transmission signal transmission is completed. Thus, it is possible to detect an object that is present at a closer distance, and more accurately detect information related to reflection in a plurality of modes.

  Here, in the second embodiment, the correlation processing unit 1123 changes the interval of the reference pattern used for obtaining the secondary correlation value according to the elapsed time after the transmission of the transmission signal is completed. According to such a configuration, an appropriate secondary correlation value can be acquired using an appropriate section of the reference pattern according to the elapsed time after the transmission of the transmission signal is completed.

  Further, in the second embodiment, the correlation processing unit 1123 uses the interval on the terminal side of the reference pattern for acquisition of the secondary correlation value as the elapsed time from completion of transmission of the transmission signal is shorter, and transmits the second correlation value. When the elapsed time from completion of signal transmission is a predetermined time or more, the entire reference pattern is used for obtaining the secondary correlation value. According to such a configuration, it is possible to appropriately set the interval of the reference pattern used for acquiring the secondary correlation value according to the relationship between the elapsed time after the transmission of the transmission signal is completed and the predetermined time. it can.

  In the second embodiment, the predetermined time is, for example, a reverberation time from immediately after transmission signal transmission is completed until vibration due to inertia of the vibrator subsides. According to such a configuration, it is possible to more appropriately set the interval of the reference pattern used for acquiring the secondary correlation value in consideration of the reverberation time.

<Modification of Second Embodiment>
Needless to say, in the second embodiment, a modification similar to the modification of the first embodiment described above can be applied. That is, the technique of the second embodiment can be applied to a configuration in which information about an object is detected by transmitting and receiving sound waves, millimeter waves, electromagnetic waves, and the like. In addition, the various processes in the second embodiment may be realized in a form that the object detection device executes under its own control, or a parking assistance control unit in which the object detection device is connected to the object detection device. It may be realized in the form of being executed under the control.

  As mentioned above, although embodiment and the modification of this indication were described, embodiment and the modification which were mentioned above are an example to the last, Comprising: It is not intending limiting the range of invention. The above-described novel embodiments and modifications can be implemented in various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The above-described embodiments and modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Vehicle 100, 100a, 101, 102, 103, 104, 1100 Object detection apparatus 110 Transmission / reception part 111a Transducer 123, 1123 Correlation processing part 124, 1124 Distance measurement part (detection part)
500 Parking assistance device 501 Parking assistance ECU (parking assistance control unit)

Claims (13)

The transmission having a transducer capable of transmitting and receiving ultrasonic waves, transmitting a transmission signal subjected to encoding that gives identification information of a predetermined code length, and reflected by an object existing around A transceiver for receiving a signal as a received signal;
Immediately after the transmission of the transmission signal is completed, a first correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal is acquired, and the first correlation value and the first threshold value are acquired. A correlation processing unit that determines whether or not the received signal to which the identification information having a similarity with the identification information of the transmission signal is equal to or higher than a predetermined level is received based on a comparison result with the transmission signal;
A detection unit that detects information related to the object when it is determined that the received signal to which the identification information having the similarity with the identification information of the transmission signal is equal to or higher than the predetermined level has been received;
An object detection device comprising: The correlation processing unit includes at least a part of the identification information of the transmission signal, from immediately after the transmission of the transmission signal is completed until the reverberation time until the vibration due to inertia of the vibrator subsides ends, Obtaining the first correlation value corresponding to the degree of similarity with at least a part of the identification information of the received signal, and based on the comparison result between the first correlation value and the first threshold value, It is determined whether or not the received signal to which the identification information having a similarity with the identification information is at a predetermined level or higher is received.
The object detection apparatus according to claim 1. The correlation processing unit has a first threshold as the first threshold value to be compared with the first correlation value immediately after the transmission of the transmission signal is completed and after the reverberation time from when the vibration due to the inertia of the vibrator subsides ends. The first threshold value and the second first threshold value as the first threshold value to be compared with the first correlation value immediately after the transmission signal transmission is completed and before the reverberation time ends are different from each other. ,
The object detection apparatus according to claim 1 or 2. The second first threshold is set so as to decrease with time.
The object detection apparatus according to claim 3. After obtaining the first correlation value, the correlation processing unit is smaller than the first pattern corresponding to the temporal change of the first correlation value, the first peak, and the first peak adjacent to the first peak. Based on a comparison result between the second correlation value and the second threshold value, the second correlation value corresponding to the degree of similarity with at least a part of the second pattern set in advance so as to include the second peak is acquired. Determining whether or not a plurality of signals have been received as the received signal to which the identification information having a level of similarity with the identification information of the transmission signal is equal to or higher than the predetermined level,
The detection unit detects information on a plurality of objects that respectively cause reflection of the plurality of signals as information on the object when it is determined that the plurality of signals are received;
The object detection apparatus of any one of Claims 1-4. The correlation processing unit changes an interval of the second pattern used for obtaining the second correlation value according to an elapsed time after the transmission of the transmission signal is completed.
The object detection device according to claim 5. The correlation processing unit uses the section on the terminal end side of the second pattern for acquisition of the second correlation value as the elapsed time after the transmission of the transmission signal is completed is shorter, When the elapsed time after the transmission is completed is equal to or longer than a predetermined time, the entire second pattern is used for obtaining the second correlation value.
The object detection apparatus according to claim 6. The predetermined time is a reverberation time from immediately after transmission of the transmission signal is completed until vibration due to inertia of the vibrator subsides.
The object detection apparatus according to claim 7. The detection unit includes a distance measurement unit that calculates a distance to the object as information on the object based on a difference between a timing at which the transmission signal is transmitted and a timing at which the reception signal is received.
The object detection apparatus of any one of Claims 1-8. The transmission having a transducer capable of transmitting and receiving ultrasonic waves, transmitting a transmission signal subjected to encoding that gives identification information of a predetermined code length, and reflected by an object existing around A transceiver for receiving a signal as a received signal;
The degree of similarity between the identification information of the transmission signal and the identification information of the reception signal after the transmission of the transmission signal is completed and until the reverberation time until the vibration due to inertia of the vibrator subsides ends. The received signal to which the identification information whose similarity with the identification information of the transmission signal is equal to or higher than a predetermined level is given based on a comparison result between the correlation value and a threshold. A correlation processing unit for determining whether or not
A detection unit that detects information related to the object when it is determined that the received signal to which the identification information having the similarity with the identification information of the transmission signal is equal to or higher than the predetermined level has been received;
An object detection device comprising: The transmission having a transducer capable of transmitting and receiving ultrasonic waves, transmitting a transmission signal subjected to encoding that gives identification information of a predetermined code length, and reflected by an object existing around A transceiver for receiving a signal as a received signal;
After the transmission of the transmission signal is completed, a first correlation value corresponding to the similarity between the identification information of the transmission signal and the identification information of the reception signal is acquired, and the time change of the first correlation value is handled Corresponding to at least a part of the second pattern preset to include the first pattern and the second peak smaller than the first peak adjacent to the first peak and the first peak. A correlation processing unit for obtaining a second correlation value;
A detection unit configured to detect information on the object based on a comparison result between the second correlation value and a threshold;
An object detection device comprising: An object detection device mounted on a vehicle, having a transducer capable of transmitting and receiving ultrasonic waves, and transmitting a transmission signal subjected to encoding to give identification information of a predetermined code length by the transducer. A transmission / reception unit that receives the transmission signal reflected by an object existing in the surroundings as a reception signal, and the identification information of the transmission signal and the identification information of the reception signal immediately after the transmission of the transmission signal is completed. The first correlation value corresponding to the degree of similarity is acquired, and the identification information whose similarity to the identification information of the transmission signal is at a predetermined level or more based on a comparison result between the first correlation value and a threshold value The reception signal to which the identification information having a level of similarity between the correlation processing unit for determining whether or not the reception signal to which the transmission signal has been received and the identification information of the transmission signal is equal to or higher than the predetermined level Is received If it is constant, a detection unit for detecting information about the object, the object detecting device comprising a,
A parking support processing unit that performs parking support of the vehicle based on information about the object that is mounted on the vehicle and detected by the detection unit of the object detection device;
A parking assistance device comprising: The object detection device includes a plurality of object detection devices,
The plurality of object detection devices detect information on the object in parallel using the different identification information,
The parking assistance device according to claim 12.

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