JP7379819B2 - Object detection device and parking assist device - Google Patents

Description

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

Conventionally, a transducer such as a piezoelectric element transmits a transmission signal as an ultrasonic wave, and the transducer receives the transmission signal reflected by an object as a reception signal, and obtains the difference in the timing of transmission and reception of those ultrasonic waves. There is a known technology for acquiring information about an object, such as the distance to the object, by doing so.

International Publication WO2016/167003 Publication

In the above-mentioned technology using a vibrator, even after the transmission of the transmission signal is completed, the vibrator continues to vibrate due to inertia, so it takes time for the vibrator to stop vibrating. Such time is called reverberation time. Here, when a received signal is received during the reverberation time, vibrations of the vibrator generated by the received signal and vibrations of the vibrator remaining due to inertia coexist. In this case, it is difficult to accurately detect only the received signal using, for example, a certain amplitude threshold, so conventionally, detection of the received signal has been avoided until the reverberation time has expired.

However, in situations where the object to be detected is very close, for example when the difference between the vehicle width and the parking frame (wall, etc.) is very small, the transmission may be delayed before the reverberation time expires. It is also possible that the signal will return. Therefore, there is a need for a technique that detects a received signal even before the reverberation time ends and realizes detection of an object that exists at a closer distance.

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 existing 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 the transducer transmits a transmission signal encoded with identification information of a predetermined code length, Immediately after the transmission of the transmitted signal is completed, a transmitting/receiving unit receives the transmitted signal reflected by surrounding objects as a received signal. 1 correlation value is obtained, and based on the comparison result between the first correlation value and the first threshold value, it is determined whether the degree of similarity between the identification information of the transmitted signal and the identification information of the received signal is at a predetermined level or higher. Detects the distance to the object based on the correlation processing unit that makes the determination and, if the similarity is at a predetermined level or higher, the transmitted signal and the received signal to which identification information whose similarity is at a predetermined level or higher is attached. and a detection unit that determines that the transmitted signal has not yet returned as a received signal due to reflection when the similarity is at a level lower than a predetermined level, and the correlation processing unit determines that transmission of the transmitted signal has been completed. from immediately until the end of the reverberation time until the vibrations due to inertia of the vibrator subside, the degree of similarity between at least part of the identification information of the transmitted signal and at least part of the identification information of the received signal is determined. Obtain a first correlation value, and determine whether the degree of similarity between the identification information of the transmitted signal and the identification information of the received signal is at a predetermined level or higher, based on the comparison result between the first correlation value and the first threshold value. Determine.

According to the above configuration, by using the identification information given to the transmitted signal (and the received signal), immediately after the transmission of the transmitted signal is completed, it is possible to determine whether the transmitted signal has been reflected and received as a received signal. It is possible to determine whether Thereby, the received signal can be detected even before the reverberation time ends, so it is possible to provide an object detection device that can detect objects that are present at a closer distance.

In addition, according to such a configuration, unlike the case where information on all code lengths of identification information is always considered, the time required to obtain (calculate) the first correlation value can be shortened, so it can be performed more quickly. Object detection can be realized.

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

Further, in the object detection device described above, the second first threshold value is set to become smaller as time passes. According to such a configuration, it is possible to obtain an appropriate second first threshold value that matches a transmitted signal (received signal) that attenuates with the passage of time (that is, an increase in propagation distance).

Further, in the object detection device described above, after acquiring the first correlation value, the correlation processing unit generates a first pattern corresponding to a time change of the first correlation value, a first peak, and a pattern adjacent to the first peak. obtain a second correlation value corresponding to the degree of similarity between at least a part of a second pattern preset to include a second peak smaller than the first peak, and set the second correlation value and a second threshold value. Based on the comparison result with the identification information of the transmitted signal, the detection unit determines whether or not a plurality of signals are received as received signals to which identification information having a degree of similarity with the identification information of the transmission signal is at a predetermined level or higher; When it is determined that a plurality of signals have been received, information regarding a plurality of objects each causing a reflection of a plurality of signals is detected as information regarding the object. According to such a configuration, information regarding reflections in a plurality of aspects can be more accurately obtained by performing two correlation processes: a correlation process to obtain the first correlation value and a correlation process to obtain the second correlation value. can be detected.

In this case, the correlation processing section changes the section of the second pattern used to obtain the second correlation value, depending on 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 depending on the elapsed time after the transmission of the transmission signal is completed. .

In addition, in this case, the shorter the elapsed time after the transmission of the transmission signal is completed, the more the correlation processing unit uses the section on the terminal side of the second pattern to obtain the second correlation value. If the elapsed time since the transmission is completed is a predetermined time or more, the entire second pattern is used to obtain the second correlation value. According to such a configuration, the section of the second pattern used to obtain the second correlation value can be appropriately set depending on the relationship between the elapsed time after the transmission of the transmission signal is completed and the predetermined time. I can do it.

Furthermore, in this case, the predetermined time is the 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, the section of the second pattern used to obtain the second correlation value can be more appropriately set in consideration of the reverberation time.

Further, in the object detection device described above, the detection unit includes a distance measurement unit that calculates the distance to the object as information about the object based on the 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 has a transducer capable of transmitting and receiving ultrasonic waves, and the transducer transmits a transmission signal encoded with identification information of a predetermined code length. There is a transmitting/receiving unit that receives the transmitted signal reflected by surrounding objects as a received signal, and a reverberation time from when the transmission of the transmitted signal is completed until the vibration due to the inertia of the vibrator subsides. During the process, a correlation value corresponding to the similarity between the identification information of the transmitted signal and the identification information of the received signal is obtained, and based on the comparison result between the correlation value and the threshold value, the identification information of the transmitted signal and the identification information of the received signal are acquired. a correlation processing unit that determines whether or not the degree of similarity with the transmitted signal is at a predetermined level or higher; and when the degree of similarity is at a predetermined level or higher, identification information that indicates that the degree of similarity with the transmitted signal is at a level higher than a predetermined level is provided. a detection unit that detects the distance to the object based on the received signal and determines that the transmitted signal has not yet returned as the received signal due to reflection when the degree of similarity is less than a predetermined level; , is provided.

According to the above configuration, the reverberation time from when the transmission of the transmission signal is completed until the vibration due to the inertia of the vibrator subsides is determined by using the identification information given to the transmission signal (and the reception signal). Until the end of the process, it can be determined whether the transmitted signal is reflected and received as a received signal. Thereby, the received signal can be detected even before the reverberation time ends, so it is possible to provide an object detection device that can detect objects that are present at a closer distance.

Further, a parking assist device as yet another example of the present disclosure is an object detection device mounted on a vehicle, and includes the above-described object detection device and a parking support device mounted on the vehicle and detected by a detection unit of the object detection device. A parking assistance processing unit that executes parking assistance for a vehicle based on information regarding the object.

According to the above configuration, by using the identification information given to the transmitted signal (and the received signal), immediately after the transmission of the transmitted signal is completed, it is possible to determine whether the transmitted signal has been reflected and received as a received signal. It is possible to determine whether As a result, the received signal can be detected even before the reverberation time ends, so it is possible to provide a parking assistance device that can detect objects that are present at a closer distance.

In the parking assistance device described above, the object detection device includes a plurality of object detection devices, and each of the plurality of object detection devices simultaneously detects information regarding the object using mutually different identification information. According to such a configuration, the situation around the vehicle can be detected more quickly and in more detail based on multiple detection results obtained simultaneously, so parking can be performed more quickly and with higher precision. Support can be realized.

FIG. 1 is an exemplary and schematic diagram showing the appearance of a vehicle equipped with an object detection device according to a first embodiment (and a second embodiment) viewed from above. FIG. 2 is an exemplary and schematic diagram showing the configuration of the object detection device according to the first embodiment. FIG. 3 is an exemplary and schematic graph showing an example of the 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 showing a series of processes executed by the object detection device according to the first embodiment to detect an object. FIG. 5 is an exemplary and schematic block diagram showing the configuration of a parking assistance device including an object detection device according to a modification of the first embodiment. FIG. 6 is an exemplary and schematic diagram for explaining the necessity of the second embodiment. FIG. 7 is an exemplary and schematic diagram showing a reference pattern according to the second embodiment. FIG. 8 is an exemplary and schematic diagram showing the results of the secondary correlation processing according to the second embodiment. FIG. 9 is an exemplary and schematic flowchart showing a series of processes executed by the object detection device according to the second embodiment to detect an object.

Embodiments of the present disclosure will be described below based on the drawings. The configuration of the embodiment described below, and the actions and results (effects) brought about by the configuration are merely examples, and are not limited to the contents described below.

<First embodiment>
FIG. 1 is an exemplary and schematic diagram showing the appearance of a vehicle 1 equipped with object detection devices 101 to 104 according to a first embodiment (and a second embodiment described later) viewed from above. Although the details will be described later, the object detection devices 101 to 104 transmit and receive ultrasonic waves and obtain the time difference between the transmission and reception, thereby detecting objects (for example, obstacles X1 shown in FIG. ) is a sensing device that detects information about

As shown in FIG. 1, the object detection devices 101 to 104 are mounted on a vehicle body 2 of a four-wheeled 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 at the rear end of the vehicle body 2, for example on the rear bumper.

Note that 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 showing the configuration of the object detection device 100 according to the first embodiment. As shown in FIG. 2, it includes a transmitting/receiving section 110 and a control section 120.

The transceiver section 110 includes a transducer 111. The transducer 111 has a vibrator 111a such as a piezoelectric element, and transmits and receives ultrasonic waves using the vibrator 111a.

More specifically, the transducer 111 transmits an ultrasonic wave generated in response to the vibration of the transducer 111a as a transmission signal, and the ultrasonic wave transmitted as the transmission signal is reflected by an external object and returned. The vibration of the vibrator 111a caused by the vibration is received as a reception signal. Note that, in FIG. 2, an obstacle X1 installed on the road surface X2 is illustrated as an object that reflects the ultrasonic waves from the transducer 111.

In the above technology using the vibrator 111a, even after the transmission of the transmission signal is completed, the vibrator 111a continues to vibrate due to inertia, so it takes time (so-called reverberation time). Here, when a 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 coexist. In this case, it is difficult to accurately detect only the received signal using, for example, a certain amplitude threshold, so conventionally, detection of the received signal has been avoided until the reverberation time has expired.

However, in situations where the object to be detected is very close, for example when the difference between the vehicle width and the parking frame (wall, etc.) is very small, the transmission may be delayed before the reverberation time expires. It is also possible that the signal will return. Therefore, there is a need for a technique that detects a received signal even before the reverberation time ends and realizes detection of an object that exists at a closer distance.

Therefore, in the first embodiment, the transmitting/receiving section 110 and the control section 120 are provided with the following hardware and functions, thereby realizing detection of an object existing at a closer distance.

In the first embodiment, the transceiver section 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 using analog circuits, for example.

The oscillator 112 oscillates a signal of a predetermined frequency for vibrating the vibrator 111a 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 transducer 111 as a voltage signal for vibrating the vibrator 111a. . Note that in the first embodiment, the modulation method may be one or a combination of commonly known methods such as an amplitude modulation method, a phase modulation method, and a frequency modulation method. Further, in the first embodiment, the modulator 113 may be configured to appropriately switch among a plurality of modulation schemes based on instructions from the control unit 120.

The demodulator 114 demodulates the signal input from the transducer 111 and outputs the demodulated signal to the control unit 120. The modulation method used is one that corresponds to the modulation method used by the modulator 113.

The control section 120 includes a storage section 121, an encoding processing section 122, a correlation processing section 123, and a distance measuring section 124. For example, in the case where the control unit 120 is configured as a processing device having hardware similar to a normal computer such as a processor and a memory, these configurations are possible as a result of the processor reading and executing a program stored in the memory. It is realized functionally (that is, through cooperation between hardware and software). Note that in the first embodiment, each part constituting the control unit 120 may be implemented in hardware using 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 uses modulation by the modulator 113 to perform encoding for adding identification information of a predetermined code length to the transmission signal. More specifically, the encoding processing unit 122 generates a bit string consisting of a series of 0 or 1 bits as identification information unique to the object detection device 100. The length of this bit string corresponds to the code length of identification information added 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. Realize encoding.

For example, when using an amplitude modulation method as a modulation method, when a bit string as identification information is input from the encoding processing unit 122, the modulator 113 transmits and receives data depending on whether each bit of the bit string is 0 or 1. The magnitude of the amplitude of the voltage signal output to the wave generator 111 is changed. Similarly, when using a phase modulation method as a modulation method, the modulator 113 outputs a voltage signal to the transducer 111 depending on whether each bit of the bit string input from the encoding processing section 122 is 0 or 1. When using a frequency modulation method as a modulation method, the frequency of the voltage signal output to the transducer 111 changes depending on whether each bit of the bit string input from the encoding processing unit 122 is 0 or 1. change.

The correlation processing unit 123 obtains a correlation value corresponding to the degree of similarity (degree of coincidence) between the identification information of the transmitted signal and the identification information of the received signal, and based on the comparison result between the correlation value and a threshold (first threshold). Then, it is determined whether the degree of similarity is at a predetermined level or higher. The correlation value exceeds the threshold and reaches its peak when the waveforms of the transmitted signal and the received signal match. Such a correlation value can be obtained (calculated) based on, for example, a generally well-known correlation function. The correlation processing unit 123 uses the correlation value obtained based on a correlation function or the like to combine the bit string generated by the encoding processing unit 122 as identification information given to the transmission signal and the bit string demodulated by the demodulator 114. It is determined whether or not the bit string as identification information specified from the received signal is similar (coincident) at a predetermined level or higher, and based on the determination result, the received signal demodulated by the demodulator 114 is It is determined whether the transmitted signal is a reflected and returned transmission signal.

The distance measurement unit 124 is a detection unit that detects information regarding an object (for example, the presence or absence of an object, the distance to the object, etc.) when it is determined that the above-mentioned similarity is at a predetermined level or higher. More specifically, the ranging unit 124 determines the timing at which the transmission signal was transmitted (more specifically, it started to be transmitted) and the timing at which the reception signal was received (more specifically, it started to be received). The distance to the object is calculated as information regarding the object using the so-called TOF (Time of Flight) method based on the difference between the distance and the object.

Here, in the first embodiment, as described above, identification information is added 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 received signal. It is determined whether the demodulated received signal is a transmitted signal that has been reflected back by an object. Identification information is basically not lost due to reflection, so based on the identification information, even if a received signal is received during the reverberation time, the vibration of the transducer 111a generated by the received signal and the inertia It becomes possible to detect only the former from the remaining vibration of the vibrator 111a.

Therefore, in the first embodiment, the correlation processing unit 123 acquires the above-mentioned 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 correlation processing unit 123 calculates the It is determined whether the degree of 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 the waveform of a signal transmitted and received by the object detection device 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 device 100 via the transducer 111 (oscillator 111a). do.

In the graph shown in FIG. 3, a solid line L11 represents an example of an envelope representing a time change in the signal level of a signal transmitted and received by the object detection device 100, that is, the degree of vibration of the vibrator 111a. From this solid line L11, it can be seen that the vibrator 111a is driven and vibrates for a time T1 from timing t0, and the transmission of the transmission signal is completed at timing t1. It can be seen that the vibration of the vibrator 111a continues while being attenuated. Therefore, in the graph shown in FIG. 3, time T2 corresponds to the so-called reverberation time.

A solid line L11 indicates that the degree of vibration of the vibrator 111a exceeds (or exceeds) a predetermined threshold Th1 represented by a dashed-dotted line L21 at timing t4, which is the time Tp that has elapsed from timing t0 when transmission of the transmission signal started. ) reaches its peak. This threshold value Th1 is an example of a first threshold value, and the reception of a received signal as a transmitted signal in which the vibration of the vibrator 111a is reflected by an object to be detected (for example, an obstacle X1 shown in FIG. 2) and returned. or by receiving a received signal as a transmitted signal reflected back by an object other than the sample target (for example, the road surface X2 shown in FIG. 2). This is a preset value for Although FIG. 3 shows an example in which the threshold Th1 is set as a constant value that does not change over time, in the first embodiment, the threshold Th1 is set as a value that changes over time. It's okay.

For example, a vibration having a peak exceeding (or more than) the threshold Th1 can be determined to be caused by the reception of a received signal as a transmitted signal that has been reflected back by the object to be detected. , it can be determined that a vibration having a peak equal to or less than the threshold Th1 is caused by the reception of a received signal as a transmitted signal reflected by an object that is not a detection target. 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 received signal as the transmitted signal reflected by the object to be detected and returned.

Note that in the solid line L11, the vibration of the vibrator 111a is attenuated after timing t4. Therefore, timing t4 is the timing when the reception of the received signal as the transmitted signal reflected by the object to be detected is completed, in other words, the transmitted signal last transmitted at timing t1 returns as the received signal. Corresponds to the timing. In addition, in the solid line L11, timing t3, which is the starting point of the peak at timing t4, is the timing when the reception of the received signal as the transmitted signal reflected by the object to be detected starts, in other words, timing t0. This corresponds to the timing at which the first transmitted signal returns as a received 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 find the distance to the object to be detected using the TOF method, it is necessary to find 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. It becomes necessary. This time Tf is calculated by subtracting a time ΔT equal to the time T1 as the transmission time of the transmitted signal from the time Tp which is the difference between the timing t0 and the timing t4 at which the signal level of the received signal reaches its peak exceeding the threshold Th1. It can be found by The timing t0 can be easily identified as the timing when the object detection device 100 starts operating, and the time T1 is predetermined by settings etc., so the distance to the object to be detected can be determined by the TOF method. It is important to specify timing t4.

Therefore, in the first embodiment, as described above, the transmission signal is subjected to predetermined encoding so that the transmission signal and the reception signal are given identification information of a predetermined code length. The first embodiment acquires a correlation value corresponding to the similarity between the identification information of the transmitted signal and the identification information of the received signal, and determines the degree of similarity based on the comparison result between the correlation value and the first threshold. It is determined whether the level is higher than a predetermined level. Note that the first threshold value to which the correlation value is compared is a value corresponding to the threshold Th1 described above. According to such a configuration, the timing at which the degree of similarity is determined to be at a predetermined level or higher can be specified as the timing t4 at which the received signal reaches a peak exceeding the threshold Th1. It becomes possible to find the distance to the object.

By the way, let us consider a case where the object to be detected is present at a short distance and the transmitted signal returns as a received signal before the reverberation time ends. In this case, in the graph shown in FIG. 3, a waveform represented by an envelope like a broken line L12 appears in the time T2 (reverberation time) between timing t1 and timing t2.

The transmitted signal that returns during the reverberation time has a small degree of attenuation because it has only propagated over a short distance, so it causes vibrations (see broken line L12) that are larger than the vibrations remaining due to inertia (see solid line L11) in the vibrator 111a. ). Therefore, in the first embodiment, even between the timing t1 when the transmission of the transmission signal is completed and the timing t2 when the reverberation time ends, the transmission signal is transmitted by the object to be detected using the same method as after the timing t2 described above. It is possible to determine whether the signal has been reflected and returned as a received signal.

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

Note that the transmitted signal is attenuated as the distance of propagation becomes longer, so the later the timing at which the transmitted signal returns as a received signal, the lower the signal level of the received signal becomes. Therefore, in the first embodiment, in order to accurately detect a received signal whose signal level decreases with time, the threshold Th2 is set to decrease with time. Note that FIG. 3 shows an example in which the dashed-dot line L21 representing the threshold Th1 and the dashed-double line L22 representing the threshold Th2 are continuous at the timing t2 when the reverberation time ends. In this embodiment, the threshold Th1 and the threshold Th2 may not be set consecutively.

In this way, the first embodiment uses the identification information of the transmitted signal and the identification information of the received signal not only after the reverberation time ends, but also from immediately after the transmission of the transmitted signal is completed until the reverberation time ends. A correlation value corresponding to the degree of similarity with the information is acquired, and based on a comparison result between the correlation value and a threshold value, it is determined whether the degree of similarity is at a predetermined level or higher.

However, in the first embodiment, a first threshold is used as a threshold to be compared with the correlation value after the reverberation time ends, and a correlation value is set between immediately after the transmission of the transmission signal is completed and until the reverberation time ends. and the second first threshold value as the threshold value to be compared are made to be different from each other. The first first threshold is a value corresponding to the threshold Th1 described above. Further, the second first threshold is a value corresponding to the threshold Th2 described above, and is set to become smaller as time passes. In the first embodiment, it is assumed that the object detection device 100 (for example, the correlation processing unit 123) itself switches between the first first threshold value and the second first threshold value. In this case, both the first threshold value and the second first threshold value are stored in the storage unit 121.

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

FIG. 4 is an exemplary and schematic flowchart showing a series of processes executed by the object detection device 100 according to the first embodiment to detect an object.

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

Then, in S402, the object detection device 100 (for example, the control unit 120) determines whether 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 passed, the process returns to S401. On the other hand, if it is determined in S402 that the predetermined time has elapsed, the process advances to S403.

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

Then, in S404, the object detection device 100 (for example, the correlation processing unit 123) determines whether the reverberation time has ended. This determination may be made based on a reverberation time that is preset according to the specs of the vibrator 111a, or by monitoring the actual vibration of the vibrator 111a to detect whether the vibration has subsided. It may be implemented by

If it is determined in S404 that the reverberation time has ended, the process proceeds to S405. Then, in S405, the object detection device 100 (for example, the correlation processing unit 123) determines whether the correlation value acquired in S403 is greater than or equal to the first first threshold set as a comparison target for correlation values after the reverberation time ends. to judge.

In S405, if it is determined that the correlation value is less than the first threshold value, the identification information of the transmitted signal and the identification information of the received signal are not similar (matched) at a predetermined level or higher, that is, the transmitted signal It can be determined that the signal has 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. Then, in S406, the object detection device 100 (for example, the correlation processing unit 123) determines whether the correlation value acquired in S403 is greater than or equal to the second first threshold set as a comparison target for correlation values during the reverberation time. to decide.

In S406, if it is determined that the correlation value is less than the second first threshold, the identification information of the transmitted signal and the identification information of the received signal are not similar (matched) at a predetermined level or higher, that is, the transmitted signal It can be determined that the signal has 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 equal to or greater than the first first threshold value, and in the case where it is determined in S406 that the correlation value is equal to or greater than the second first threshold value, the transmitted signal It can be determined that the identification information of the received signal and the identification information of the received signal are similar (coinciding) at a predetermined level or higher, that is, the transmitted signal has returned as a received signal due to reflection. Therefore, in this case, the process advances to the next step S407.

In S407, the object detection device 100 (for example, the distance measuring unit 124) determines the timing at which the transmission signal was transmitted (more specifically, the transmission started) and when the reception signal as the transmission signal returned by reflection was received. The distance to the object that reflected the transmission signal is obtained (calculated) using the TOF method based on the difference between the timing when the signal was received (more specifically, when the signal began to be received), and the time when the transmission signal started to be received. Then, the process ends.

As described above, the object detection device 100 according to the first embodiment includes the transmitting/receiving section 110, the correlation processing section 123, and the distance measuring section 124 configured as follows. The transmitting/receiving unit 110 has a transducer 111a capable of transmitting and receiving ultrasonic waves, and the transducer 111a transmits a transmission signal encoded with identification information of a predetermined code length, and transmits a transmission signal that is reflected by an object. The transmitted signal is received as a received signal. Immediately after the transmission of the transmission signal is completed, the correlation processing unit 123 acquires a correlation value corresponding to the degree of similarity between the identification information of the transmission signal and the identification information of the reception signal, and calculates the correlation value and the first threshold value (described above). Based on the comparison result with the first first threshold or the second first threshold, it is determined whether the degree of similarity is at a predetermined level or higher corresponding to the threshold. The distance measuring unit 124 detects information regarding the object (distance to the object) when it is determined that the degree of similarity is at a predetermined level or higher.

According to the above configuration, by using the identification information given to the transmitted signal (and the received signal), immediately after the transmission of the transmitted signal is completed, it is possible to determine whether the transmitted signal has been reflected and received as a received signal. It is possible to determine whether Thereby, the received signal can be detected even before the reverberation time ends, so it is possible to detect objects that are 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 are provided as shown in FIG. When a transmitted signal is returned as a received signal, it is possible to prevent other object detection devices 100 from erroneously detecting the received signal. That is, in the first embodiment, the object detection devices 101 to 104 can simultaneously detect information about objects using mutually different identification information. According to such a configuration, the situation around the vehicle 1 can be detected more quickly and in more detail based on a plurality of detection results obtained simultaneously. Parking assistance can be realized.

<Modified example>
Note that in the above description, the technology of the first embodiment is applied to a configuration that detects information about an object by transmitting and receiving ultrasonic waves, but the technology of the first embodiment is applicable to waves other than ultrasonic waves. It can also be applied to a configuration that detects information about an object by transmitting and receiving sound waves, millimeter waves, electromagnetic waves, etc.

Furthermore, in the first embodiment described above, the object detection device 100 has a configuration in which it controls operations such as switching the modulation method of the transmission signal and switching between the first threshold value and the second threshold value. Illustrated. However, these operations may also be realized under external control, as in a variant described below.

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

The object detection device 100a is a sensing device that detects information regarding objects existing in the surroundings, similar to the object detection device 100 according to the first embodiment described above. Furthermore, the parking assistance ECU 501 is a microcomputer that serves as a parking assistance control unit that implements parking assistance (including automatic parking). The object detection device 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 modified example, the basic hardware configuration and functions of the transmitting/receiving 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 modified example, operations performed in the object detection device 100a, such as switching the modulation method of the transmission signal and switching between the first first threshold value and the second first threshold value, are controlled by the parking assist ECU 501. This embodiment differs from the first embodiment described above in that it is realized under the following conditions. 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 regarding the object is detected based on (the peak of) the correlation value obtained as a result of one correlation process. However, as shown in FIG. 6 below, for example, it may be difficult to accurately detect information about an object just by considering the correlation value obtained as a result of one correlation process.

FIG. 6 is an exemplary and schematic diagram for explaining the necessity of the second embodiment. In the example shown in FIG. 6, the solid line L610 represents the pattern of time change in the correlation value based on the transmitted signal that has returned at a strong level due to reflection from a hard object or reflection from a nearby object, for example. The broken line L620 is an envelope representing a pattern of temporal changes in correlation values based on a transmitted signal that is returned at a weak level due to reflection from a soft object or reflection from a distant object, for example. It is a line.

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

Note that in the example shown in FIG. 6, for simplicity, there is one side lobe on each side of the main lobe, and the levels (sizes) of these two side lobes are approximately the same. In reality, two or more sidelobes may exist, and the levels of each sidelobe may vary.

In addition, in the example shown in FIG. 6, for convenience of explanation, the pattern of time change of two types of correlation values according to reflection in two different modes is the solid line L610 corresponding to reflection in the first mode. , and a broken line L620 corresponding to reflection in the second mode. However, since the mode of reflection cannot usually be distinguished in advance, the pattern of temporal change in the correlation value actually obtained in the correlation process 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 the first peak called the main lobe that can be compared with the threshold (first threshold). 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 when viewed, 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 the object that causes reflection in the second manner.

Therefore, the object detection device 1100 (see FIG. 2) according to the second embodiment detects a plurality of (for example, two types) of objects, such as the example shown in FIG. 6, based on the configuration and processing described below. Even in situations where temporal changes in multiple (for example, two types) of correlation values in response to reflections in different modes appear partially overlapping, it is possible to obtain more information about each object that causes reflection in each mode. Achieve accurate detection.

Note that 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 section 1123 and the ranging section 1124 of the control section 1200 are different from those in the first embodiment described above.

More specifically, in the second embodiment, the correlation processing unit 1123 first performs correlation processing similar to that in the first embodiment described above to determine the similarity between the identification information of the transmitted signal and the identification information of the received signal. Obtain a first correlation value. For example, in the example shown in FIG. 6, a pattern in which the solid line L610 and the broken line L620 are combined corresponds to the temporal change in the first correlation value. In addition, below, a 1st correlation value may be described as a primary correlation value, and the correlation process for acquiring the said primary correlation value may be described as a primary correlation process. The primary correlation process can be obtained based on a generally well-known correlation function.

In the second embodiment, the correlation processing unit 1123 calculates the degree of similarity between the first pattern corresponding to the time change of the first correlation value and at least a part of a preset reference pattern as a second pattern. A second correlation value corresponding to is obtained. The reference pattern is information as shown in FIG. 7, which is obtained 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. In addition, below, a 2nd correlation value may be described as a secondary correlation value, and the correlation process for acquiring the said secondary correlation value may be described as a secondary correlation process. Similarly to the above-mentioned first-order correlation processing, the second-order correlation processing can also be obtained based on a generally well-known correlation function.

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

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

Therefore, if (secondary) correlation processing is performed on the reference pattern shown by the solid line L700 and the pattern obtained by combining the solid line L610 and the broken line L620 shown in FIG. From the pattern in which the solid line L610 and the broken line L620 are combined, information regarding the pattern indicated by the solid line L610 and information relating to the pattern indicated by the broken line L620 can be obtained in a form that is separated to some extent. In other words, according to the second-order correlation processing, from information in which information regarding reflections in multiple aspects is mixed and indistinguishable from each other (the above-mentioned first-order correlation value), reflections as shown in FIG. It is possible to obtain information separated at a certain level for each aspect.

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

In addition, in the example shown in FIG. 8, for convenience of explanation, the pattern of time change of the secondary correlation value is shown divided into a solid line L801 and a broken line L802. However, similar to the relationship between the solid line L610 and the broken line L602 shown in FIG. 6, the pattern of time change 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 pattern of temporal changes in secondary correlation values actually obtained in secondary correlation processing is separated to a certain level into multiple (for example, two) patterns that have peaks at different positions in the time series. . For example, in the example shown in FIG. 8, the pattern of temporal change in the secondary correlation value is separated to some extent into a pattern shown by a solid line L801 and a pattern shown by a broken line L802.

Here, the pattern shown by the solid line L801 is a pattern that appears due to the similarity between the solid line L610 shown in FIG. 6 and the solid line L700 shown in FIG. 7, and the pattern shown by the broken line L802 is This pattern appears because the broken line L620 shown in FIG. 6 and the solid line L700 shown in FIG. 7 are similar. Since the pattern shown by the solid line L801 and the pattern shown by the broken line L802 reach their peaks at different positions in the time series, two different types of reflections are detected from the secondary correlation values shown in FIG. It is possible to do so.

In this way, according to the secondary correlation processing, information regarding reflections in a plurality of aspects can be obtained in a form separated at a certain level for each reflection aspect. Therefore, by setting an appropriate threshold Th800 and comparing the threshold Th800 with the secondary correlation value, it is possible to appropriately detect information regarding reflection in each aspect at once. Note that the threshold Th800 is an example of a "second threshold".

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

Then, by considering the timing at which the transmission signal was transmitted and the timing at which the two different types of reception signals described above were received, information regarding each of the objects that cause reflection in the two types described above can be detected. be able to. That is, by considering the difference between the timing at which the transmission signal was transmitted and the timing at which the first reception signal was received, it is possible to detect the distance to the object that causes the reflection in the first aspect. , by considering the difference between the timing at which the transmission signal was transmitted and the timing at which the second reception signal was received, it is possible to detect the distance to the object that causes the reflection in the second mode.

As described above, according to the second embodiment, even in a situation where temporal changes in a plurality of first-order correlation values in response to reflections in a plurality of different aspects appear in a partially overlapping manner, the second-order correlation Based on the values, it is possible to more accurately detect information about each object that causes reflection in each aspect.

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

More specifically, after acquiring the primary correlation value, the correlation processing unit 1123 acquires the secondary correlation value, and based on the comparison result between the second correlation value and the second threshold, identifies the transmission signal with the identification information. It is determined whether a plurality of signals have been received as received signals to which identification information having a degree of similarity equal to or higher than a predetermined level is provided. Then, when it is determined that a plurality of signals have been received, the distance measuring unit 1124 collects information regarding a plurality of objects that cause reflections of a plurality of signals (distances to each of the plurality of objects) as information regarding the object. Detect.

By the way, as mentioned above, if we focus on the vibrator 111a from immediately after the transmission of the transmission signal is completed (for example, immediately after timing t1 in FIG. 3) until the reverberation time has elapsed, we can see that the vibration remaining due to inertia (see solid line L11) ) (see broken line L12) is easy to detect, but vibrations smaller than the vibration remaining due to inertia (see solid line L11) are difficult to detect. Therefore, since it is not always possible to accurately detect all time changes in the signal level of the received signal during the reverberation time, the first-order correlation value during the reverberation time detects all the main lobes and side lobes as usual (i.e., the reference pattern (in a form similar to the whole of).

Therefore, in the second embodiment, the correlation processing unit 1123 changes the section of the reference pattern used to obtain the secondary correlation value, depending on the elapsed time after the transmission of the transmission signal is completed. For example, if the elapsed time after the transmission of the transmitted signal is completed is longer than the reverberation time, all time changes in the signal level of the received signal can be detected, so the primary correlation value is similar to that of the entire reference pattern. expected to show a pattern. On the other hand, if the elapsed time after the transmission of the transmitted signal is completed is less than the reverberation time, only the terminal side part after the reverberation time has elapsed among the time changes in the signal level of the received signal can be detected. It is expected that the correlation value will show a pattern similar only to the terminal side portion of the reference pattern in time series. 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 to obtain the secondary correlation value; In this case, a section W701 on the terminal side of a part 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 shorter the elapsed time after the completion of transmission of the transmission signal, the more the correlation processing unit 1123 uses the section on the terminal side of the reference pattern to obtain the secondary correlation value. If the time is longer than the predetermined time, the entire reference pattern is used to obtain the secondary correlation value. Note that the predetermined time can be set to match, for example, 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 obtain an appropriate secondary correlation value using an appropriate reference pattern depending on the elapsed time after the transmission of the transmission signal is completed.

FIG. 9 is an exemplary and schematic flowchart showing 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 to include identification information of a predetermined code length, similarly to the first embodiment described above.

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

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

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

Then, in S905, the object detection device 1100 (for example, the correlation processing unit 1123) performs threshold processing to compare the secondary correlation value acquired in S904 with the above-mentioned predetermined second threshold. In this threshold processing, based on the comparison result between the quadratic correlation value and the second threshold, information regarding reflections in multiple aspects, more specifically, if the similarity with the identification information of the transmitted signal is higher than a predetermined value. It is determined whether a plurality of signals have been received as received signals to which identification information having a level has been added.

Then, in S906, the object detection device 1100 (for example, the distance measuring unit 1124) obtains the distance to the object based on the result of the threshold processing in S905. More specifically, when it is determined that a plurality of signals have been received in the threshold processing in S905, the object detection device 1100 generates information ( (distance to each of multiple objects). Then, the process ends.

As described above, the object detection device 1100 according to the second embodiment includes the correlation processing section 1123 and the distance measuring section 1124. After the transmission of the transmission signal is completed, the correlation processing unit 1123 obtains a primary correlation value corresponding to the degree of similarity between the identification information of the transmission signal and the identification information of the reception signal, and calculates the primary correlation value corresponding to the temporal change in the primary correlation value. The degree of similarity between the first pattern and at least a part of a reference pattern as a second pattern that is preset to include a first peak and a second peak that is smaller than the first peak adjacent to the first peak. Obtain the corresponding secondary correlation value. The distance measuring unit 1124 detects information regarding 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, after acquiring the primary correlation value, the correlation processing unit 1123 creates a first pattern (see FIG. 6) corresponding to the temporal change of the primary correlation value and a preset pattern. A secondary correlation value (see FIG. 8) corresponding to the degree of similarity between at least a part of the reference pattern (see FIG. 7) as the two patterns is obtained, and a comparison result between the secondary correlation value and the second threshold value is obtained. Based on this, it is determined whether a plurality of signals have been received as received signals to which identification information having a degree of similarity with the identification information of the transmitted signal is equal to or higher than a predetermined level. Then, when it is determined that a plurality of signals have been received, the distance measuring unit 1124 collects information regarding a plurality of objects that cause reflections of a plurality of signals (distances to each of the plurality of objects) as information regarding the object. Detect.

According to the above configuration, two correlation processes, the correlation process to obtain the first correlation value and the correlation process to obtain the second correlation value, can be performed after the transmission of the transmission signal is completed. With this, it is possible to realize detection of an object existing at a closer distance, and it is also possible to more accurately detect information regarding reflection in a plurality of modes.

Here, in the second embodiment, the correlation processing unit 1123 changes the section of the reference pattern used to obtain the secondary correlation value, depending on the elapsed time after the transmission of the transmission signal is completed. According to such a configuration, it is possible to obtain an appropriate secondary correlation value using an appropriate section of the reference pattern depending on the elapsed time after the transmission of the transmission signal is completed.

In addition, in the second embodiment, the correlation processing unit 1123 uses the section on the terminal side of the reference pattern to obtain the secondary correlation value, and transmits If the elapsed time since the completion of signal transmission is longer than a predetermined time, the entire reference pattern is used to obtain the secondary correlation value. According to such a configuration, it is possible to appropriately set the section of the reference pattern used to obtain 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. can.

Note that in the second embodiment, the above-mentioned predetermined time is, for example, the 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, the section of the reference pattern used to obtain the secondary correlation value can be more appropriately set in consideration of the reverberation time.

<Modified example of second embodiment>
It goes without saying that modifications similar to those of the first embodiment described above can also be applied to the second embodiment. That is, the technique of the second embodiment can also be applied to a configuration that detects information about an object by transmitting and receiving sound waves, millimeter waves, electromagnetic waves, and the like. Further, the various processes in the second embodiment may be implemented by the object detection device under its own control, or the object detection device may be executed by a parking assistance control unit connected to the object detection device. It may also be realized by executing under the control of.

Although the embodiments and modifications of the present disclosure have been described above, the embodiments and modifications described above are merely examples, and are not intended to limit the scope of the invention. The novel embodiments and modified examples described above can be implemented in various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The above-described embodiments and modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

1 Vehicle 100, 100a, 101, 102, 103, 104, 1100 Object detection device 110 Transmission/reception section 111a Vibrator 123, 1123 Correlation processing section 124, 1124 Distance measurement section (detection section)
500 Parking support device 501 Parking support ECU (parking support control unit)

Claims (11)

It has a transducer capable of transmitting and receiving ultrasonic waves, and the transducer transmits a transmission signal encoded with identification information of a predetermined code length, and the transmission signal is reflected by surrounding objects. a transmitting/receiving unit that receives the 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 a first threshold are obtained. a correlation processing unit that determines whether the degree of similarity between the identification information of the transmitted signal and the identification information of the received signal is at a predetermined level or higher based on a comparison result;
When the degree of similarity is at a predetermined level or higher, the distance to the object is detected based on the transmitted signal and the received signal to which the identification information for which the degree of similarity is at a level equal to or higher than the predetermined level. and a detection unit that determines that the transmitted signal has not yet returned as the received signal due to reflection when the degree of similarity is less than a predetermined level ,
The correlation processing unit may process at least a portion of the identification information of the transmission signal and the The first correlation value corresponding to the degree of similarity with at least a part of the identification information of the received signal is acquired, and based on the comparison result between the first correlation value and the first threshold, the determining whether the degree of similarity between the identification information and the identification information of the received signal is at a predetermined level or higher;
Object detection device. The correlation processing unit is configured to calculate a first correlation value as the first threshold value to be compared with the first correlation value after a reverberation time period from immediately after the transmission of the transmission signal is completed until vibrations due to inertia of the vibrator subsides. A first threshold value and a second first threshold value as the first threshold value to be compared with the first correlation value between immediately after the transmission of the transmission signal is completed and until the reverberation time ends are different from each other. Let,
The object detection device according to claim 1. The second first threshold is set to decrease over time.
The object detection device according to claim 2. After acquiring the first correlation value, the correlation processing unit generates a first pattern corresponding to a time change of the first correlation value, a first peak, and a first peak that is smaller than the first peak adjacent to the first peak. A second correlation value corresponding to the degree of similarity between at least a part of a second pattern preset to include a second peak is obtained, and based on a comparison result between the second correlation value and a second threshold value. determining whether a plurality of signals have been received as the received signal to which the identification information having a degree of similarity with the identification information of the transmission signal is equal to or higher than the predetermined level;
When it is determined that the plurality of signals have been received, the detection unit detects, as information regarding the object, a distance to a plurality of objects that each cause a reflection of the plurality of signals.
The object detection device according to any one of claims 1 to 3. The correlation processing unit changes the section of the second pattern used to obtain the second correlation value according to the elapsed time after the transmission of the transmission signal is completed.
The object detection device according to claim 4. The correlation processing unit uses a section on the terminal side of the second pattern to obtain the second correlation value as the elapsed time from completion of transmission of the transmission signal is shorter. If the elapsed time since the transmission is completed is equal to or greater than a predetermined time, the entire second pattern is used to obtain the second correlation value;
The object detection device according to claim 5. The predetermined time is a reverberation time from immediately after the transmission of the transmission signal is completed until vibrations due to inertia of the vibrator subside.
The object detection device according to claim 6. The detection unit includes a distance measurement unit that calculates a distance to the object as information regarding 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 device according to any one of claims 1 to 7. It has a transducer capable of transmitting and receiving ultrasonic waves, and the transducer transmits a transmission signal encoded with identification information of a predetermined code length, and the transmission signal is reflected by surrounding objects. a transmitting/receiving unit that receives the signal as a received signal;
The degree of similarity between the identification information of the transmitted signal and the identification information of the received signal during the period from when the transmission of the transmitted signal is completed until the end of the reverberation time until vibrations due to inertia of the vibrator subside. , and based on a comparison result between the correlation value and a threshold, determine whether the degree of similarity between the identification information of the transmitted signal and the identification information of the received signal is at a predetermined level or higher. a correlation processing unit that determines whether
When the degree of similarity is at a predetermined level or higher, the distance to the object is detected based on the transmitted signal and the received signal to which the identification information for which the degree of similarity is at a level equal to or higher than the predetermined level. a detection unit that determines that the transmitted signal has not yet returned as the received signal due to reflection when the degree of similarity is at a level lower than a predetermined level ;
An object detection device equipped with. An object detection device mounted on a vehicle, the object detection device according to any one of claims 1 to 9;
a parking assistance processing unit that is mounted on the vehicle and executes parking assistance for the vehicle based on information regarding the object detected by the detection unit of the object detection device;
A parking assistance device equipped with The object detection device includes a plurality of object detection devices,
The plurality of object detection devices simultaneously detect information regarding the object using the different identification information.
The parking assistance device according to claim 10.

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