Object detection device, object detection method, and object detection program product

Abstract

The present invention relates to an object detection device (1) that detects an object (B) around a moving body (V) by being mounted on the moving body (V), and includes a reverberation measuring section (591), an object detection section (594), and a characteristic setting section. The reverberation measuring section measures a frequency of a reverberation signal generated in a transceiver (2) that transmits a transmission wave as an ultrasonic wave to the outside and receives a reception wave including an object-based reflection wave of the transmission wave. The object detection section detects an object based on the reception wave. The characteristic setting section that sets a transmission characteristic and / or a reception characteristic in the transceiver is a transmission control section (51) that sets a transmission characteristic of the transmission wave, and / or a circuit characteristic setting section (52) that sets a circuit characteristic in the transceiver, and the transmission characteristic and / or the reception characteristic is reduced when the reverberation frequency is measured by the reverberation measuring section than when the object is detected by the object detection section.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an object detection device that detects an object around a moving body and an object detection method. In addition, the present disclosure relates to an object detection program executed by the above-described object detection device. BACKGROUND

[0002] Patent Literature 1 discloses one example of an ultrasonic sonar. The ultrasonic sonar transmits an ultrasonic wave from an ultrasonic transducer and performs obstacle detection by receiving the ultrasonic wave reflected by an obstacle through the ultrasonic transducer. The ultrasonic sonar described in Patent Literature 1 detects an abnormality based on a result of reverberation time and frequency analysis after ultrasonic wave transmission is stopped.

[0003] Patent Literature 1: Japanese Patent No. 4267161 SUMMARY

[0004] Analysis of the reverberation signal, that is, measurement of the reverberation frequency, can be used for detection of an abnormality including attachment of foreign matter such as mud, correction of the transmission frequency, and the like. Therefore, it is required to perform analysis of the reverberation signal with as high precision as possible. The present disclosure is completed in view of the above-described exemplified cases and the like. That is, the present disclosure provides, for example, a device structure, a method, and a program capable of performing analysis of the reverberation signal with as high precision as possible.

[0005] The object detection device is configured to be mounted on a moving body and thereby detect an object around the moving body.

[0006] According to one aspect of the present disclosure, the object detection device includes:

[0007] a reverberation measuring section that measures a frequency of a reverberation signal generated at a transceiver, the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflection wave based on the transmission wave from the object;

[0008] an object detection section that detects the object based on the reception wave; and

[0009] a characteristic setting section that sets a transmission characteristic and / or a reception characteristic in the transceiver,

[0010] the characteristic setting section is configured to be a transmission control section that sets the transmission characteristic of the transmission wave and / or a circuit characteristic setting section that sets a circuit characteristic in the transceiver, and the transmission characteristic and / or the reception characteristic is reduced when the reverberation frequency is measured by the reverberation measuring section than when the object is detected by the object detection section.

[0011] According to another aspect of the present disclosure, the object detection method is an object detection method of detecting an object around a moving body, including the following processing or steps:

[0012] setting a transmission characteristic and / or a reception characteristic in a transceiver that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including a reflection wave based on the object from the transmission wave,

[0013] measuring a frequency of a reverberation signal generated in the transceiver, that is, a reverberation frequency,

[0014] detecting the object based on the reception wave,

[0015] in the setting of the transmission characteristic and / or the reception characteristic, the transmission characteristic and / or the reception characteristic is reduced when measuring the reverberation frequency than when detecting the object.

[0016] According to another aspect of the present disclosure, an object detection program is a program executed by an object detection device configured to detect an object around a mobile body by being mounted on the mobile body,

[0017] the process executed by the object detection device includes:

[0018] setting a transmission characteristic and / or a reception characteristic in a transceiver that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including a reflection wave based on the object from the transmission wave;

[0019] measuring a frequency of a reverberation signal generated in the transceiver, that is, a reverberation frequency; and

[0020] detecting the object based on the reception wave,

[0021] in the process of setting the transmission characteristic and / or the reception characteristic, the transmission characteristic and / or the reception characteristic is reduced when measuring the reverberation frequency than when detecting the object.

[0022] Further, in each column of the application file, a bracketed reference sign is sometimes attached to each element. However, the reference sign is only an example of a correspondence relationship between the same element and a specific unit described in the embodiments described later. Thus, the present disclosure is not at all limited by the description of the reference sign. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a block diagram showing a brief structure of an object detection device according to the embodiments.

[0024] Figure 2 is a brief circuit diagram showing an equivalent circuit structure in a part of the transceiver shown in FIG. 1. Figure 1

[0025] Figure 3 ​It means Figure 1 The timeline of an example of the operation of the object detection device shown.

[0026] Figure 4A It means in Figure 2 The circuit diagram shown is a graph illustrating the frequency characteristics when switch SW is turned on.

[0027] Figure 4B It means in Figure 2 The circuit diagram shown is a graph of the frequency characteristics when switch SW is turned off.

[0028] Figure 5A It means based on Figure 1 A summary time diagram of an example of the reverberation frequency measurement operation of the object detection device shown.

[0029] Figure 5B It is an enlarged representation Figure 5A A portion of the timeline.

[0030] Figure 6 It means Figure 1 A flowchart illustrating an example of the operation of the object detection device shown.

[0031] Figure 7 It means Figure 6 The flowchart shown is an example of a frequency offset calculation process.

[0032] Figure 8 It means Figure 6 The flowchart shown is an example of a main drive frequency correction process.

[0033] Figure 9 It means based on Figure 1 A summary time diagram of another example of the reverberation frequency measurement operation of the object detection device shown.

[0034] Figure 10 It means based on Figure 1 A summary time diagram of another example of the reverberation frequency measurement operation of the object detection device shown. Detailed Implementation

[0035] (Implementation Method)

[0036] Hereinafter, embodiments of the present disclosure will be described based on the accompanying drawings. Furthermore, various modifications applicable to a single embodiment may hinder understanding of that embodiment if inserted midway through a series of descriptions related to that embodiment. Therefore, modifications are described collectively after the description of the embodiments.

[0037] (structure)

[0038] If referenceFigure 1 The object detection device 1 is configured to detect an object B outside the vehicle V as a mobile body. Hereinafter, a state in which the object detection device 1 is mounted on the vehicle V is referred to as a "vehicle-mounted state". In addition, hereinafter, the vehicle V on which the object detection device 1 according to the present embodiment is mounted is referred to as the "own vehicle".

[0039] The object detection device 1 has a structure of a so-called ultrasonic sensor. Specifically, the object detection device 1 is configured to detect an object B around by transmission and reception of an ultrasonic wave, and acquire ranging information corresponding to the object B. The object detection device 1 is communicably connected to an external device, such as an obstacle detection ECU not shown, which controls various operations such as an object detection operation in the own vehicle and notification accompanying the same, via a vehicle-mounted network line. ECU is an abbreviation of Electronic Control Unit.

[0040] The object detection device 1 includes a transceiver 2, a drive signal generation section 3, a reception signal processing section 4, and a control section 5. The object detection device 1 has a structure in which the transceiver 2, the drive signal generation section 3, the reception signal processing section 4, and the control section 5 are housed and supported by one sensor housing.

[0041] The transceiver 2 is configured to transmit a transmission wave as an ultrasonic wave to the outside, and receive a reflection wave based on the object B. In the present embodiment, the object detection device 1 has a transceiving integrated structure. That is, the object detection device 1 is configured to include one transceiver 2, and thereby the transceiver 2 functions as a transceiver.

[0042] The transceiver 2 includes a transducer 21 and a transceiving circuit 22. The transducer 21 having a function of electromechanical conversion is configured as an ultrasonic microphone in which an electromechanical energy conversion element is built in a substantially cylindrical microphone housing. The transducer 21 outputs a transmission wave of an ultrasonic wave corresponding to an input electric signal, and conversely outputs an electric signal corresponding to an input reception wave of an ultrasonic wave. In the present embodiment, the transducer 21 includes a piezoelectric element as the electromechanical energy conversion element. In the vehicle-mounted state, the transducer 21 is disposed at a position facing an outer surface of the own vehicle, and thereby is arranged to be able to transmit a transmission wave to the outside of the own vehicle and to be able to receive a reflection wave from the outside of the own vehicle.

[0043] Specifically, the transducer 21 is mounted to the outer panel member V1 in the vehicle-mounted state so that the transceiving face 23 is exposed to the outside space of the host vehicle from the mounting hole V2, which is a through-hole, formed in the outer panel member V1 of the host vehicle. The outer panel member V1 is, for example, a bumper or a body panel, and is formed of a synthetic resin or a metal plate. The transceiving face 23 is an outer surface of the aforementioned microphone case in the transducer 21, and is provided to function as a transmission face of a transmission wave and a reception face of a reception wave. Further, the function and structure of the transducer 21 have become known or well-known at the filing date of the present application. Therefore, further detailed description of the function and structure of the transducer 21 is omitted in the present specification.

[0044] The transceiver 2 is provided with one transducer 21 and one transceiving circuit 22, respectively. The transducer 21 is electrically connected to the transceiving circuit 22. The transceiving circuit 22 has a digital / analog conversion circuit, an amplification circuit, an analog / digital conversion circuit, and the like.

[0045] The transceiving circuit 22 is configured to drive the transducer 21 based on the input drive signal, thereby causing the transducer 21 to transmit a transmission wave of a frequency corresponding to the frequency of the drive signal. The drive signal is a signal for driving the transceiver 2 to cause the transmission wave to be transmitted from the transducer 21, and is, for example, a pulse-shaped signal having a frequency within an ultrasonic wave band. Hereinafter, the frequency of the drive signal will be referred to as a "drive frequency".

[0046] In addition, the transceiving circuit 22 is configured to generate a reception signal by performing analog / digital conversion processing or the like on the element output signal, and output the reception signal to the reception signal processing section 4. The element output signal is an alternating voltage signal generated and output by the transducer 21 by vibration of the transceiving face 23 when the transceiving face 23 is excited by reception of the reception wave or the like. In the "reception signal", not only reception of the reception wave but also a reception signal generated due to reverberation occurring in the transceiver 2 after the drive signal is cut off. Hereinafter, the reception signal generated due to the reverberation will be referred to as a "reverberation signal". Further, the function and structure of the transceiving circuit 22 have become known or well-known at the filing date of the present application. Therefore, further detailed description of the function and structure of the transceiving circuit 22 is omitted in the present specification.

[0047] The drive signal generation section 3 is provided to generate the drive signal based on a control signal received from the control section 5, and output the drive signal to the transceiver 2, i.e., the transceiving circuit 22. The control signal is a signal for controlling the output of the drive signal from the drive signal generation section 3 to the transceiver 2.

[0048] The drive signal generation section 3 is provided to generate and output a drive signal corresponding to a waveform pattern encoded in a transmission wave according to the waveform pattern. Specifically, the drive signal generation section 3 is configured to selectively generate and output a chirp drive signal in which the transmission wave is a chirp wave and a CW drive signal in which the transmission wave is a CW wave. The chirp wave is a wave in which the frequency increases or decreases over time. The CW wave is a wave in which the frequency is constant. CW is an abbreviation for continuous waveform. The CW wave is also referred to as a CF wave. CF is an abbreviation for continuous frequency. The chirp wave is one type of FM wave. FM is an abbreviation for frequency modulation.

[0049] The reception signal processing section 4 is configured to generate an amplitude signal and a frequency signal by performing various signal processing on the reception signal. The amplitude signal is a signal corresponding to the amplitude of the reception signal. The frequency signal is a signal corresponding to the frequency of the reception signal. That is, the frequency signal is a signal corresponding to the waveform pattern related to the encoding in the reception signal. Specifically, the reception signal processing section 4 includes a filter processing section 41, an amplitude signal generation section 42, and a frequency signal generation section 43.

[0050] The filter processing section 41 is provided to perform filter processing for removing noise from the reception signal. The amplitude signal generation section 42 is provided to generate and output the amplitude signal based on the reception signal after the filter processing by the filter processing section 41. The frequency signal generation section 43 is provided to generate and output the frequency signal based on the reception signal after the filter processing by the filter processing section 41.

[0051] Further, the functions and structures of the filter processing section 41, the amplitude signal generation section 42, and the frequency signal generation section 43 are already known or well-known at the time of filing of the present application. Therefore, further detailed description of the functions and structures of the filter processing section 41, the amplitude signal generation section 42, and the frequency signal generation section 43 is omitted in the present specification.

[0052] The control section 5 is provided to control the overall operation of the object detection apparatus 1. Specifically, in the present embodiment, the control section 5 is a known microcomputer, and is provided with a CPU, a ROM, a non-volatile rewritable memory, a RAM, an input / output interface, and the like. The CPU is an abbreviation of Central Processing Unit. The ROM is an abbreviation of Read Only Memory. The non-volatile rewritable memory is, for example, an EPROM, an EEPROM, a flash memory, a magnetic recording medium, or the like. The EPROM is an abbreviation of Erasable Programmable Read Only Memory. The EEPROM is an abbreviation of Electrically Erasable Programmable Read Only Memory. The RAM is an abbreviation of Random access memory. The ROM, the non-volatile rewritable memory, and the RAM are non-transitory tangible storage media. The ROM and / or the non-volatile rewritable memory correspond to a storage medium that stores an object detection program related to the present embodiment.

[0053] The control section 5 is configured to execute various processes by reading out a program stored in the ROM or the non-volatile rewritable memory and executing the program. Specifically, the control section 5 is configured to control the transmission of the transmission wave in the transceiver 2, and to detect the object B on the basis of the reception wave received by the transceiver 2. That is, the control section 5 has a structure as an ECU built in the ultrasonic sensor.

[0054] The control section 5 has the following functional elements as functional structures realized on the microcomputer. That is, the control section 5 has a transmission control section 51, a circuit characteristic setting section 52, a filter characteristic setting section 53, an amplitude signal acquisition section 54, a frequency signal acquisition section 55, a delay correction section 56, a specific interval detection section 57, a measurement interval setting section 58, and a reception determination section 59.

[0055] The transmission control section 51 is provided to control the transmission state of the transmission wave from the transceiver 2 by outputting a control signal to the drive signal generation section 3. Specifically, the transmission control section 51 sets the drive frequency, the waveform pattern, the output timing, and the like in the drive signal generated and output by the drive signal generation section 3 by the control signal. In addition, the transmission control section 51 sets the drive current and the drive voltage by the control signal. The drive current and the drive voltage are the current and the voltage applied to the transducer 21.

[0056] The transmission control section 51, which is a characteristic setting section that sets a transmission characteristic and / or a reception characteristic in the transceiver 2, is provided to control or set a transmission characteristic of a transmission wave. That is, the transmission control section 51 is configured to control a sound pressure of a transmission wave using a transmission output characteristic of a pulse number, a drive current, a drive voltage, a duty ratio, and the like. In the present embodiment, the transmission control section 51 sets different transmission output characteristics (for example, a pulse number) in the pre-drive and the main drive. The so-called main drive is an application, that is, an output of a drive signal to the transceiver 2 at the time of a main measurement for acquiring ranging information for detecting the object B. The so-called pre-drive is an application, that is, an output of a drive signal to the transceiver 2 at the time of a pre-measurement for measuring a reverberation frequency. The reverberation frequency is a frequency of a reverberation signal. Hereinafter, in order to avoid lengthening of the description, "transmission / reception characteristic" is used in the present specification in the sense of a transmission characteristic and / or a reception characteristic.

[0057] The transmission control section 51 is configured to lower the transmission characteristic at the time of the pre-drive than at the time of the main drive. Specifically, the transmission control section 51 lowers the sound pressure of the transmission wave using a low pulse number at the time of the pre-drive than at the time of the main drive. In addition, the transmission control section 51 controls transmission of the transmission wave in the transceiver 2 so that the transmission wave is frequency-modulated as a chirp wave at the time of the main measurement, that is, the main drive, and is not frequency-modulated as a CW wave at the time of the pre-measurement, that is, the pre-drive.

[0058] The transmission control section 51 is provided to correct a drive frequency in accordance with a measurement result of the reverberation frequency of the transceiver 2 based on the pre-measurement. At this time, the transmission control section 51 sets a correction value of the drive frequency decided based on the measurement result of the reverberation frequency to a prescribed range.

[0059] The circuit characteristic setting section 52, which is a characteristic setting section that sets a transmission / reception characteristic in the transceiver 2, is provided to set a circuit characteristic in the transceiver 2. In the present embodiment, the circuit characteristic setting section 52 is configured to set different circuit characteristics at the time of a pre-measurement based on a reverberation frequency measurement of the pre-drive and at the time of a main measurement based on detection of the object B of the main drive. Specifically, the circuit characteristic setting section 52 sets a parallel connection state of a resistance connected in parallel to the transducer 21 in the transceiving circuit 22 to different states at the time of the pre-measurement and at the time of the main measurement. In addition, the circuit characteristic setting section 52 is configured to lower the reception characteristic at the time of the pre-drive than at the time of the main drive.

[0060] Figure 2 A portion on the secondary side that is a connection portion with the transducer 21 in the transceiving circuit 22 is shown together with an equivalent circuit of the transducer 21. Figure 2 In the present embodiment, the inductance LT and the resistance RT correspond to a secondary side winding provided in a transformer of the transceiving circuit 22. A portion on the primary side in the transceiving circuit 22 including a primary side winding of the above-described transformer is omitted from the drawing and the description.

[0061] The capacitance CI, the inductance LI, and the resistance Rl express the mechanical vibration in the transducer 21 as an equivalent circuit. By the series connection of the capacitance CI, the inductance LI, and the resistance Rl, a series resonance circuit RCs is constituted. The capacitance C2 is a capacitance component in the piezoelectric element defined by the distance between electrodes of the piezoelectric element, the electrode area, the dielectric constant of the piezoelectric body, and the like, and is connected in parallel with the series resonance circuit RCs in the equivalent circuit.

[0062] By the secondary side winding provided in the transformer of the transceiver circuit 22, the capacitance C2 in the transducer 21, the capacitor C3, and the resistance R2, a parallel resonance circuit RCp is constituted. The capacitor C3 is connected in parallel with the transducer 21 in order to adjust the temperature characteristics in the transceiver 2, and to adjust the resonance frequency in the parallel resonance circuit RCp. The resistance R2 is connected in parallel with the transducer 21 and the capacitor C3 in order to adjust the reverberation time and the amplification rate.

[0063] Further, the resistance R3 and the switch SW are provided in the parallel resonance circuit RCp. The resistance R3 is provided to function as an attenuator that reduces the amplification rate, and to realize the suitability of the reverberation frequency characteristics by reducing the Q value. The resistance R3 is connected in parallel with the transducer 21, the resistance R2, and the capacitor C3 via the switch SW. The switch SW is a so-called semiconductor switch, and is provided to be turned on and off by the control section 5, that is, the circuit characteristics setting section 52. The circuit characteristics setting section 52 turns on the switch SW at the time of the preliminary measurement, and on the other hand, turns off the switch SW at the time of the pre-drive, the main drive, and the main measurement.

[0064] Referring again to Figure 1 , the filter characteristics setting section 53 is provided to set the filter frequency condition in the filter processing section 41. That is, the filter characteristics setting section 53 adjusts the frequency band of the signal passing through the filter processing section 41 according to the change in the transmission frequency caused by the attachment of a foreign matter in the transceiver face 23, or the like. The "transmission frequency" is the frequency of the transmission wave. Specifically, the filter characteristics setting section 53 adjusts the above-mentioned frequency band based on the measurement result of the reverberation frequency.

[0065] The amplitude signal acquisition section 54 is provided to acquire the amplitude signal from the amplitude signal generating section 42. The frequency signal acquisition section 55 is provided to acquire the frequency signal from the frequency signal generating section 43. The delay correction section 56 is provided to correct the delay time generated between the amplitude signal and the frequency signal.

[0066] The specific-interval detecting section 57 is configured to detect a specific interval. The specific interval is an interval in which a difference frequency caused by a plurality of reverberation frequency components is considered to be generated in a reverberation signal. The difference frequency in the reverberation signal is a transitional phenomenon generated by a shift of the plurality of reverberation frequency components, accompanied by a relatively large frequency change and / or a relatively large amplitude break. If the reverberation frequency is measured in the above-mentioned interval in which the difference frequency is generated, the measurement accuracy is greatly reduced. In contrast to this, the non-specific interval is an interval in which the above-mentioned difference frequency is hardly considered to be generated. If the reverberation frequency is measured in the above-mentioned non-specific interval, the measurement accuracy is good.

[0067] Therefore, in the present embodiment, the specific-interval detecting section 57 detects a reverberation break interval in which a waveform break is generated in an amplitude signal corresponding to an amplitude of the reverberation signal, as a specific interval, that is, an interval in which the difference frequency is generated. Specifically, the specific-interval detecting section 57 detects a portion in which the amplitude signal is smaller than a reverberation break determination threshold in an interval before a gentle portion in which the amplitude signal decreases in a converging manner, as the interval in which the difference frequency is generated. In addition, the specific-interval detecting section 57 detects the specific interval on the basis of the correction result of the delay correcting section 56.

[0068] The measurement-interval setting section 58 is configured to set a measurement interval on the basis of the detection result of the specific interval of the specific-interval detecting section 57, in a non-specific interval. In the present embodiment, the measurement interval is an interval in which the reverberation frequency is measured, that is, calculated, in a pre-measurement. Specifically, the measurement-interval setting section 58 determines the non-specific interval by excluding the specific interval from an interval in which the pre-measurement is performed. Furthermore, the measurement-interval setting section 58 sets the measurement interval in the determined non-specific interval. More specifically, the measurement-interval setting section 58 sets the determined non-specific interval as the measurement interval.

[0069] The reception-determining section 59 is configured to perform various operations such as determination, diagnosis, detection, and the like, related to a reception signal, on the basis of the amplitude signal acquired in the amplitude-signal acquiring section 54 and the frequency signal acquired in the frequency-signal acquiring section 55. Specifically, the reception-determining section 59 has a reverberation measuring section 591, a diagnosis section 592, a code determining section 593, and an object detecting section 594.

[0070] The reverberation measuring section 591 is configured to measure, that is, calculate, the reverberation frequency in the measurement interval set by the measurement-interval setting section 58. The reception-determining section 59 hands over the measurement result of the reverberation frequency of the reverberation measuring section 591 to the transmission control section 51. In addition, the reception-determining section 59 hands over the measurement result of the reverberation frequency of the reverberation measuring section 591 to the filter characteristic setting section 53, so that the filter band adjustment performed by the filter characteristic setting section 53.

[0071] The diagnosis section 592 is configured to determine the presence or absence of an abnormality in the transducer 2 based on the amplitude signal and the frequency signal in the reverberation signal. That is, the diagnosis section 592 determines the presence of a disconnection, freezing, or foreign matter attachment based on the measurement result of the reverberation frequency by the reverberation measurement section 591. Specifically, the diagnosis section 592 determines that an abnormality in the transducer 2 is present when the measurement result of the reverberation frequency is outside a normal range set in advance by measurement or the like. Also, when it is determined that an abnormality in the transducer 2 is present, the diagnosis section 592 classifies the above abnormality into any one of a foreign matter attachment state, a freezing state, and a disconnection state according to the amount of deviation from the normal range, and outputs the classification result. Note that, for the abnormality determination based on the analysis result of the reverberation signal, for example, an abnormality determination that has become known or is known at the time of filing of the present application can be used. Therefore, the details of the abnormality determination are omitted from the description in the present specification.

[0072] The code determination section 593 is configured to determine a code corresponding to the frequency modulation method in the received wave. Specifically, the code determination section 593 determines whether the received wave is a normal wave based on the frequency signal acquired in the frequency signal acquisition section 55 and a predetermined reference signal stored in advance. The "normal wave" is a received wave in a case where the transducer 2 receives a reflected wave of the transmission wave transmitted by itself. In contrast, the received wave caused by a transmission wave from another device will be referred to as a "non-normal wave" hereinafter. The "another device" also includes another transducer 2 mounted on the host vehicle. Specifically, the code determination section 593 determines whether the received wave is a normal wave by performing pattern matching of the waveforms of the frequency signal and the reference signal.

[0073] The object detection section 594 is configured to detect the object B based on the received wave, that is, the received signal. That is, the object detection section 594 is configured to detect the object B based on the code determination result of the code determination section 593. Specifically, the object detection section 594 detects the presence of the object B and the distance between the transducer 21 and the object B based on the amplitude signal acquired by the amplitude signal acquisition section 54 and the like in a case where the received wave is a normal wave.

[0074] (Action Outline)

[0075] Hereinafter, the object detection device 1 according to the present embodiment, the object detection method executed thereby, and the object detection program will be referred to simply as "the present embodiment". Hereinafter, an outline of the action of the present embodiment will be described with reference to the drawings and together with the effects achieved by the present embodiment.

[0076] If the prescribed object detection condition is satisfied, the object detection device 1 starts an object detection operation. The object detection condition includes, for example, the traveling speed of the host vehicle being within a prescribed range, the moving position of the host vehicle being a traveling position including backing, and the like. If the object detection condition becomes not satisfied, the object detection device 1 ends the object detection operation.

[0077] In the object detection operation, the transmission control section 51 determines the arrival of the transmission process start timing at a prescribed cycle. The prescribed cycle is, for example, a cycle of several hundred milliseconds. The arrival of the transmission process start timing is determined using a timer or the like provided to the control section 5. If the transmission process start timing arrives, the transmission control section 51 outputs a control signal toward the drive signal generation section 3. As a result, the transmission process is executed.

[0078] Specifically, if the drive signal generation section 3 is input with the control signal, it generates a drive signal and outputs it toward the transceiver 2, that is, the transceiving circuit 22. The drive signal is output from the transmission process start timing to the transmission process end timing.

[0079] The transceiving circuit 22 drives the transducer 21 based on the input drive signal. As a result, the transducer 21 transmits an ultrasonic wave, that is, a transmission wave, of a frequency corresponding to the frequency of the drive signal toward the outside of the host vehicle. In this way, the object detection device 1 repeatedly transmits the transmission wave at a prescribed cycle in the object detection operation. Therefore, the prescribed cycle described above is also referred to as a "transmission cycle".

[0080] If the transmission process end timing arrives, the transceiver 2 outputs a reception signal that is an alternating voltage signal. After the transmission process end timing, a reverberation occurs in the transceiver 2. Therefore, the transceiver 2 outputs a reverberation signal.

[0081] The transceiver 2 executes a reception operation during a prescribed receivable period in the object detection operation. The receivable period is, in the structure of the present embodiment in which the transceiving is integrated, a period in which a dead zone due to the influence of reverberation or the like is removed from among the period between the transmission process end timing in the present transmission process and the transmission process start timing in the next transmission process. The transceiver 2 outputs an alternating voltage signal, that is, a reception signal, corresponding to the amplitude and frequency of the reception wave during the receivable period.

[0082] The reception signal processing section 4 generates an amplitude signal and a frequency signal by performing various signal processes on the reception signal. Specifically, the filter processing section 41 removes noise from the reception signal by performing a filter process on the reception signal. The amplitude signal generation section 42 generates an amplitude signal based on the reception signal after the filter process by the filter processing section 41. The frequency signal generation section 43 generates a frequency signal based on the reception signal after the filter process by the filter processing section 41. The reception signal processing section 4 outputs the generated amplitude signal and frequency signal to the control section 5.

[0083] In the control section 5, the amplitude signal acquisition section 54 acquires the amplitude signal from the amplitude signal generation section 42. The frequency signal acquisition section 55 acquires the frequency signal from the frequency signal generation section 43. The reception determination section 59 performs various actions such as determination, diagnosis, detection, and the like related to the reception signal based on the amplitude signal acquired in the amplitude signal acquisition section 54 and the frequency signal acquired in the frequency signal acquisition section 55.

[0084] Specifically, the reverberation measurement section 591 measures the reverberation frequency. The diagnosis section 592 determines the presence or absence of abnormality generation in the transceiver 2 based on the measurement result of the reverberation frequency of the reverberation measurement section 591. The diagnosis section 592 performs processing corresponding to the modality of the determined abnormality in a case where it is determined that abnormality is generated. For example, the diagnosis section 592 transmits an attachment determination signal to an external device not shown in a case where it is determined that attachment of a foreign matter in the transceiving surface 23. Thereby, an alarm of the intention that the ultrasonic sensor has attached a foreign matter such as mud, snow, or the like is issued to the occupant of the host vehicle.

[0085] The code determination section 593 determines the code corresponding to the frequency modulation pattern in the reception wave at the time of detecting the object B. That is, the code determination section 593 determines whether the reception wave is a normal wave based on the frequency signal acquired in the frequency signal acquisition section 55 and a prescribed reference signal stored in advance. The object detection section 594 detects the presence of the object B and the distance of the transducer 21 from the object B based on the amplitude signal acquired by the amplitude signal acquisition section 54 and the like in a case where the reception wave is a normal wave.

[0086] The transceiving surface 23 in the transducer 21 is exposed to the outside space of the host vehicle in the vehicle-mounted state. Therefore, a foreign matter such as mud, snow, or the like is sometimes attached to the transceiving surface 23. If a foreign matter is attached to the transceiving surface 23, the resonance frequency in the transceiver 2 changes. Nevertheless, if the driving frequency before the attachment of the foreign matter is directly applied, the strength of the transmission wave is unintentionally reduced, or the like, and the transceiving characteristics are reduced. In addition, in the case of chirp coding of the transmission wave, the modulation pattern, that is, the change pattern of the frequency in the transmission wave deviates from the prescribed pattern due to the attachment of the foreign matter. Then, the recognition rate of the code is reduced.

[0087] At this point, the reverberation frequency also changes in conjunction with the resonance frequency change based on the attachment of the foreign matter. Therefore, the driving frequency is corrected by the transmission control section 51 based on the measurement result of the reverberation frequency of the transceiver 2. In addition, the filter characteristic setting section 53 adjusts the frequency band of the signal passing through the filter processing section 41 to fit the corrected driving frequency. Thereby, even in an environment in which a foreign matter such as mud, snow, or the like is easily attached to the ultrasonic sensor, good transceiving characteristics and a code recognition rate can be achieved.

[0088] Furthermore, a predetermined error may occur in the measurement results of the reverberation frequency. In particular, a relatively large error may occur due to instantaneous phenomena such as electrical noise. Therefore, there is a concern about making inappropriate or excessive corrections in the correction of the drive frequency based on the reverberation frequency measurement results. In this regard, the transmission control unit 51 protects or limits the correction value of the drive frequency determined based on the reverberation frequency measurement results using a protection value. That is, for example, the transmission control unit 51 sets the correction value of the drive frequency or its change within a predetermined range. Specifically, for example, the transmission control unit 51 can limit the absolute value of the correction value or its change to below a predetermined value. As a result, inappropriate or excessive corrections can be effectively suppressed.

[0089] As is well known, when object B is within a close range, the timing of the received reflected wave may occur during reverberation. Additionally, as... Figure 2 As shown, in transceiver 2, in addition to the series resonant circuit RCs originating from transducer 21, a parallel resonant circuit RCp originating from the connection between transducer 21 and transceiver circuit 22 is also formed. Therefore, the reverberation frequency is affected not only by the series resonant frequency of the series resonant circuit RCs, but also by the parallel resonant frequency of the parallel resonant circuit RCp. Due to the attachment of foreign matter, the circuit constant in the series resonant circuit RCs changes, while the circuit constant in the parallel resonant circuit RCp remains unchanged. Therefore, under transceiver conditions where the influence of the parallel resonant frequency is greater, there are concerns that the anomaly detection of measurement results based on the reverberation frequency and the accuracy of drive frequency correction may not be good.

[0090] Therefore, in this embodiment, before the main drive and main measurement for detecting object B, a pre-drive and prediction amount that reduces the transceiver characteristics are executed. Specifically, the transmission control unit 51 and / or the circuit characteristic setting unit 52, which are characteristic setting units for setting the transceiver characteristics in transceiver 2, reduce the transceiver characteristics when the reverberation frequency is measured by the reverberation measurement unit 591 compared to when object B is detected by the object detection unit 594.

[0091] Figure 3 This represents a summary of the pre-driving and predictive operations performed during the predictor period Tp, and the main driving and main measurement operations performed during the subsequent main measurement period Tm. Figure 3 In the diagram, the vertical axis S represents the received signal, and the horizontal axis T represents the time. Additionally, Dp represents the drive signal in the pre-drive phase, and Dm represents the drive signal in the main drive phase. SZp represents the reverberation signal in the predicted quantity, and SRp represents the received signal of the reflected wave in the predicted quantity. SZm represents the reverberation signal in the main measurement phase, and SRm represents the received signal of the reflected wave in the main measurement phase. Tz is the measurement interval used to measure the reverberation frequency.

[0092] The pre-drive is output of a drive signal that is initially performed after the object detection condition is established. That is, if the object detection condition is established, the object detection device 1 first performs the pre-drive and the pre-measurement, and then performs the main drive and the main measurement using the results of the pre-measurement.

[0093] The transmission control section 51 reduces the sound pressure at the time of the pre-measurement for measuring the reverberation frequency by the reverberation measurement section 591, compared to the time of the main drive for detecting the object B by the object detection section 594. That is, the transmission control section 51 performs the pre-drive under the condition that the output is reduced compared to the main drive. Specifically, the transmission control section 51 sets the number of pulses in the pre-drive to be smaller than the number of pulses in the main drive.

[0094] Thus, the influence of the parallel resonance circuit RCp at the time of measuring the reverberation frequency can be reduced as much as possible. That is, by reducing the number of pulses, the generation of the difference frequency can be well suppressed. In addition, the influence of the pre-drive on the main drive and the main measurement can be suppressed as much as possible. Also, the influence of the reflected wave generated by the object B existing in the close range at the time of measuring the reverberation frequency can be reduced as much as possible. Therefore, the measurement of the reverberation frequency, and the abnormality determination and the drive frequency correction based on the measured reverberation frequency can be performed with high precision. In addition, the pre-measurement period Tp can be shortened as much as possible.

[0095] In the present embodiment, the transmission control section 51 frequency-modulates the transmission wave as a chirp wave at the time of detecting the object B by the object detection section 594. Thus, the recognition accuracy of the regular wave and the irregular wave is improved. In particular, by encoding the transmission wave with a plurality of bits, the recognition accuracy can be further improved.

[0096] On the other hand, if the drive frequency is frequency-modulated, the reverberation frequency is influenced by the drive frequency, so that stable reverberation frequency measurement with high precision is difficult. Therefore, the transmission control section 51 controls the transmission of the transmission wave in the transceiver 2 so that the transmission wave is not frequency-modulated at the time of measuring the reverberation frequency by the reverberation measurement section 591. That is, the drive signal in the pre-drive is set to a CW drive signal of a single frequency. As the above-mentioned single frequency, for example, the designed value of the series resonance frequency can be used. Thus, stable reverberation frequency measurement with high precision can be performed.

[0097] The circuit characteristic setting section 52 sets the transceiving circuit 22 to different circuit characteristics at the time of the pre-measurement for measuring the reverberation frequency by the reverberation measurement section 591, and at the time of the main measurement for detecting the object B by the object detection section 594. Specifically, the circuit characteristic setting section 52 sets the parallel connection state of the resistors in the parallel resonance circuit RCp in the transceiving circuit 22 to be different in the pre-measurement and the main measurement. More specifically, the circuit characteristic setting section 52 connects the resistor Rl in the parallel resonance circuit RCp in the transceiving circuit 22 in parallel in the pre-measurement, and connects the resistor Rl in series in the main measurement. Figure 2 The switch SW shown in the drawing is turned on in the pre-measurement, and on the other hand, is turned off in the main measurement.

[0098] Figure 4A Frequency characteristics of transceiving sensitivity in the transceiver 2 in a state in which the switch SW is turned on. Figure 4B Frequency characteristics of transceiving sensitivity in the transceiver 2 in a state in which the switch SW is turned off.

[0099] As shown in FIG. 2, the transceiver 2 has a series resonance circuit RCs and a parallel resonance circuit RCp on an equivalent circuit. Therefore, in a case where a driving frequency is assumed to be substantially equal to a series resonance frequency, frequency characteristics of transceiving sensitivity in a state in which the switch SW is turned off become a form having two peak values sandwiching the above-described driving frequency, as shown by a solid line in FIG. 3. Frequencies corresponding to the above-described two peak values are generated by a synthesis or interaction of the series resonance and the parallel resonance, and are different from both the series resonance frequency and the parallel resonance frequency. Further, even if circuit constants such as a resistance value in the parallel resonance circuit RCp are optimized in the state in which the switch SW is turned off, the frequency characteristics stay at a frequency characteristic in which the two peak values are substantially horizontally connected, as shown by a dotted line in FIG. 3. Figure 2 Figure 4B Figure 4B

[0100] On the other hand, by turning on the switch SW, a state in which the resistance R2 and the resistance R3 are connected in parallel is achieved. The above-described state substantially becomes equivalent to lowering the resistance value of the resistance R2. In the above-described state, as shown in FIG. 4, a frequency difference in the above-described two peak values becomes small, and typically becomes a state in which the peak values can be regarded as one. In this state, a difference frequency in reverberation is alleviated. In addition, a difference between a resonance frequency and a reverberation frequency in the transceiver 2 becomes small, and precision of establishment of the measured reverberation frequency and the resonance frequency increases. Therefore, measurement of the reverberation frequency, and abnormality determination and driving frequency correction based on the measured reverberation frequency can be performed with high precision. Figure 4A

[0101] Figure 5A Figure 5B Indicates one example of a reverberation signal. Figure 5B Is an enlarged view of a region surrounded by a dotted line in FIG. 5. In FIG. 5, the horizontal axis T indicates a time, and the vertical axis S indicates a reverberation signal waveform. In FIG. 5, Tv indicates an application interval of a driving signal, that is, a transmission interval, SA indicates an amplitude signal corresponding to the reverberation signal, and f indicates a frequency signal. THr is a reverberation time determination threshold value. A time at which a reference time Tr at which the amplitude signal decreases to the reverberation time determination threshold value THr after the transmission interval Tv ends is traced back by a prescribed time is determined as a start point of a time interval in which reverberation occurs, that is, a reverberation time. Figure 5A Figure 5A Figure 5B Figure 5A

[0102] ​​​​​​​​​As mentioned above, the reverberation frequency is affected not only by the series resonant frequency of the series resonant circuit RCs, but also by the parallel resonant frequency of the parallel resonant circuit RCp. This results in multiple reverberation frequency components, generating a difference frequency in the reverberation signal. The difference frequency generated in the reverberation signal is as follows: Figure 5A as well as Figure 5B The portion enclosed by the dashed ellipse in the middle shows waveform breakage in both the reverberation signal and the amplitude signal corresponding to its amplitude.

[0103] like Figure 5A As with time intervals Tg1 and Tg2, peak-shaped reverberation frequencies that deviate significantly from the frequency characteristics of transceiver 2 are observed in time intervals containing difference frequencies or waveform breaks. Therefore, if the reverberation frequency is measured in such time intervals, the measurement accuracy is significantly reduced. On the other hand, as with time intervals Tn1 and Tn2, the amplitude of reverberation frequency variation is smaller in time intervals where waveform breaks do not occur. Good measurement accuracy of the reverberation frequency is obtained in such time intervals.

[0104] Therefore, the specific interval detection unit 57 detects the specific interval as either the interval in which the reverberation signal generates a difference frequency caused by multiple reverberation frequency components, or the non-generating interval in which the aforementioned difference frequency is hardly generated. Furthermore, based on the detection results of the specific interval, the measurement interval setting unit 58 sets a measurement interval in the non-generating interval for the reverberation frequency to be measured by the reverberation measurement unit 591.

[0105] Specifically, in this embodiment, the specific interval detection unit 57 detects the reverberation breakage interval where waveform breakage occurs in the amplitude signal corresponding to the amplitude of the reverberation signal as the generation interval. Figure 5A In the example, the specific interval detection unit 57 detects the portion of the time interval before the gradual decrease in amplitude signal in the reverberation in a convergent manner, where the amplitude signal is less than the reverberation breakage determination threshold THd, as the generation interval. The detected specific interval, i.e. the generation interval, is... Figure 5A In the example, the first generation interval Tg1 and the second generation interval Tg2 are used. The smooth part is a time interval within a specified range around time Tr.

[0106] Based on the detected generation intervals, non-generation intervals can be determined. That is, by excluding generation intervals from the reverberation time, non-generation intervals can be identified. Specifically, in Figure 5A In the example, the first generating interval Tg1 and the second generating interval Tg2 are excluded from the reverberation time determined by the reference time Tr, thereby determining the first non-generating interval Tn1 and the second non-generating interval Tn2. The first non-generating interval Tn1 can also be referred to as the non-generating interval in the time interval before the smooth portion, i.e., the intermediate non-difference frequency interval. The second non-generating interval Tn2 includes the smooth portion.

[0107] Further, the measurement interval setting section 58 sets the measurement interval in each of the time intervals excluding the generation intervals, i.e., the non-generation intervals. Specifically, in the example shown in FIG. 6, the measurement interval setting section 58 sets the measurement interval in each of the first non-generation interval Tnl as the intermediate non-difference frequency interval and the second non-generation interval Tn2 including the flat portion. Figure 5A

[0108] The present embodiment measures the reverberation frequency in the non-generation interval in which the difference frequency is hardly considered to be generated. In particular, in the flat portion, the tendency that the reverberation frequency converges to a constant value is known from the case where the reverberation frequency varies in the second non-generation interval Tn2 shown in FIG. 6. Thus, the measurement accuracy of the reverberation frequency is improved. In addition, the abnormality determination and the drive frequency correction based on the measured reverberation frequency can be performed with high accuracy. Figure 5A

[0109] However, a delay time caused by a processing time difference between the amplitude signal generation section 42 and the frequency signal generation section 43 can be generated between the amplitude signal and the frequency signal. Specifically, in order to generate the amplitude signal in the amplitude signal generation section 42, a filtering process needs to be performed. Thus, in the case where the frequency signal is generated in the frequency signal generation section 43 using the zero-crossing method or the like, a relatively large delay time is generated.

[0110] Thus, the delay correction section 56 corrects the delay time generated between the amplitude signal corresponding to the amplitude of the reverberation signal and the frequency signal corresponding to the reverberation frequency. Further, the specific interval detection section 57 detects the specific interval based on the correction result of the delay correction section 56. Thereby, the setting of the measurement interval can be appropriately performed.

[0111] In the present embodiment, the diagnosis section 592 determines the presence or absence of an abnormality generation in the transceiver 2 based on the reverberation frequency measured with good accuracy as described above. Specifically, in the example shown in FIG. 6, the diagnosis section 592 determines the presence or absence of an abnormality generation in the transducer 21 based on the reverberation frequency in the first non-generation interval Tnl and the second non-generation interval Tn2. Figure 5A

[0112] Thus, the measurement interval setting section 58 sets the measurement interval Tz in each of the plurality of non-generation intervals. Specifically, in the example shown in FIG. 6, the measurement interval setting section 58 sets the measurement interval Tz in each of the first non-generation interval Tnl as the intermediate non-difference frequency interval and the second non-generation interval Tn2 including the flat portion. Figure 6 to Figure 8 ​​​In the example, measurement intervals Tz are set in each of the first non-generating interval Tn1 before the smooth section and the second non-generating interval Tn2 including the smooth section. Furthermore, the diagnostic unit 592 diagnoses the transceiver 2 malfunction based on the measurement results of the reverberation frequencies in each of the multiple measurement intervals Tz.

[0113] That is, for example, the diagnostic unit 592 diagnoses the presence or absence of foreign matter attachment based on the measurement results of the reverberation frequency in the time interval corresponding to the smooth portion, i.e., the second non-generation interval Tn2. Thus, high-precision foreign matter attachment determination is possible. Furthermore, for example, in addition to the time interval corresponding to the smooth portion, i.e., the second non-generation interval Tn2, the diagnostic unit 592 also determines the presence or absence of anomalies in the transceiver 2 based on the measurement results of the reverberation frequency in the time interval preceding the smooth portion, i.e., the first non-generation interval Tn1. Therefore, according to this embodiment, high-precision anomaly determination is possible.

[0114] In this embodiment, the transmission control unit 51 corrects the drive frequency of the transceiver 2 based on the reverberation frequency measured with good accuracy as described above. This enables excellent transmission and reception characteristics. In particular, when the transmitted wave is chirped-coded, a good code recognition rate can be achieved.

[0115] As detailed above, according to this embodiment, reverberation signal analysis can be performed with the highest possible accuracy. Furthermore, according to this embodiment, various actions such as transmission frequency correction and anomaly detection can be appropriately performed based on the high-precision reverberation signal analysis results. In particular, in reverberation frequency measurement, when using measurement methods such as the zero-crossing method or quadrature detection based on instantaneous values ​​to reduce computational load without using FFT (i.e., high-speed Fourier transform), there is a significant concern about accuracy degradation caused by difference frequencies. In this regard, according to this embodiment, even with methods such as the zero-crossing method, the computational load can be reduced, and reverberation frequency measurement results can be obtained with good measurement accuracy.

[0116] (Example of action)

[0117] The following uses Figure 6 The flowchart shown illustrates an example of a specific action or process in this embodiment. Furthermore, in the accompanying drawings, "step" is simply referred to as "S".

[0118] If the object detection conditions are met, the object detection device 1, i.e., the CPU in the control unit 5, will begin... Figure 7The object detection device 1 executes the object detection operation shown in the flowchart. If the object detection operation is started, first, in step 601, the object detection device 1 executes pre-drive. Specifically, the object detection device 1 drives the transducer 21 using a CW drive signal of a prescribed small number of pulses, thereby transmitting a low-output pre-measurement transmission wave. Further, in the case where the number of pulses is 1 or 2, even if the changing process of the drive frequency pattern is not performed, the drive signal becomes a CW drive signal as a matter of course. That is, in the pre-drive, even if the drive frequency pattern for the chirp wave is used, it is possible to realize a CW wave-like drive signal and transmission wave by merely reducing the number of pulses.

[0119] Next, in step 602, the object detection device 1 executes pre-measurement. The pre-measurement is started after the end of the pre-drive interval or at a prescribed timing after the end of the pre-drive interval. In the pre-measurement, the object detection device 1 measures the reverberation frequency on the basis of the amplitude signal and the frequency signal in the reverberation signal.

[0120] Next, in step 603, the object detection device 1 determines the presence or absence of abnormality generation in the transceiver 2 on the basis of the measured reverberation frequency. That is, the object detection device 1 determines the presence or absence of abnormality and the abnormality type on the basis of the measured reverberation frequency and a prescribed reference value. As the reference value of the reverberation frequency, for example, a design value, a measured value at the time of factory shipment of the object detection device 1, or the like can be used.

[0121] In the case where some abnormality is generated in the transceiver 2 (i.e., step 603 = No), the object detection device 1 advances the process to step 604. In step 604, the object detection device 1 determines whether the determined or detected abnormality is an abnormality of a type that enables continuation of the object detection operation, for example, whether it is foreign matter attachment, icing, or the like.

[0122] In the case where it is an abnormality that cannot continue the object detection operation (i.e., step 604 = No), the object detection device 1 ends the object detection operation after executing the process of step 605. The abnormality that cannot continue the object detection operation is, for example, a broken wire or the like.

[0123] In step 605, the object detection device 1 executes various processes in the case where the abnormality that cannot continue the object detection operation is generated. Specifically, for example, the object detection device 1 executes a process required to notify the abnormality generation of the transceiver 2 to the occupant of the host vehicle and / or a service factory or the like.

[0124] In the case of an abnormality in which the object detection operation can be continued (i.e., Step 604 = Yes), the object detection device 1 executes the process of Step 606 and advances the process to Step 607. In Step 606, the object detection device 1 executes a process for notifying the occupant of the host vehicle that the foreign matter attachment or icing has occurred in the transceiver 2. In addition, in the case of normality of the transceiver 2 (i.e., Step 603 = Yes), the object detection device 1 advances the process to Step 607.

[0125] In Step 607, the object detection device 1 calculates the frequency offset Δf. In the present action example, the frequency offset Δf is an amount of deviation of the resonance frequency in the transceiver 2. The detailed situation of the calculation process of the frequency offset Δf based on Step 607 will be described later using the flowchart of Figure 8 . After that, the object detection device 1 advances the process to Step 608.

[0126] In Step 608, the object detection device 1 determines whether the frequency offset Δf is smaller than a threshold value Δf_th. In the case of the frequency offset Δf being equal to or larger than the threshold value Δf_th (i.e., Step 608 = No), the object detection device 1 executes the process of Step 609 and advances the process to Step 610. In contrast, in the case of the frequency offset Δf being smaller than the threshold value Δf_th (i.e., Step 608 = Yes), the object detection device 1 skips the process of Step 609 and advances the process to Step 610.

[0127] In Step 609, the object detection device 1 executes a correction process of the main drive frequency. The main drive frequency is the drive frequency in the main drive. The detailed situation of the correction process of the main drive frequency based on Step 609 will be described later using the flowchart of Figure 7 .

[0128] The object detection device 1 executes the processes of Steps 610 to 614 in order. First, in Step 610, the object detection device 1 executes the main drive. Specifically, the object detection device 1 drives the transducer 21 using the chirp drive signal, thereby transmitting a transmission wave for main measurement to which a code corresponding to the frequency modulation method is imparted.

[0129] Next, in Step 611, the object detection device 1 executes the main measurement. Then, in Step 612, the object detection device 1 acquires the main measurement result, i.e., the amplitude signal and the frequency signal in the main measurement, in the control section 5. Furthermore, in Step 613, the object detection device 1 detects the object B based on the acquired main measurement result.

[0130] In step 614, the object detection device 1 determines whether to terminate the object detection operation. The object detection operation terminates, for example, when the object detection condition changes from true to false. Alternatively, the object detection operation terminates, for example, when a predetermined termination operation is performed by an occupant of the vehicle.

[0131] If the object detection operation continues (i.e., step 614 = No), the object detection device 1 returns to step 610 and executes the processing of steps 610 to 614 again. On the other hand, if the object detection operation ends (i.e., step 614 = Yes), the object detection device 1 ends the object detection operation.

[0132] Figure 6 express Figure 8 This is an example of the frequency offset Δf calculation process in step 607 of the flowchart shown. In the frequency offset Δf calculation process, the object detection device 1 sequentially executes the processes of steps 701 to 702.

[0133] In step 701, the object detection device 1 acquires a reference value fr_ref for the reverberation frequency. Specifically, the CPU in the control unit 5 reads the reference value fr_ref for the reverberation frequency from a ROM or a non-volatile rewritable memory.

[0134] In step 702, the object detection device 1 calculates the deviation of the resonant frequency in the transceiver 2, i.e., the frequency offset Δf, based on the measurement result of the reverberation frequency fr. Specifically, the frequency offset Δf is the difference between the measured reverberation frequency fr and the reference value fr_ref.

[0135] Thus, in this specific example, the deviation of the resonant frequency in transceiver 2, i.e., the frequency offset Δf, is calculated based on the deviation between the reverberation frequency fr and the reference value fr_ref.

[0136] Figure 6 express Figure 6 This is an example of the main drive frequency correction process in step 609 of the flowchart shown. In the main drive frequency correction process, the object detection device 1 first executes the processes of steps 801 to 804 sequentially.

[0137] In step 801, the object detection device 1 acquires or calculates a provisional correction value Me based on the frequency offset Δf. The provisional correction value Me can be calculated, for example, using the frequency offset Δf and a prescribed formula. Specifically, for example, the provisional correction value Me can be calculated by the sum or product of the frequency offset Δf and a value fc corresponding to a temperature correction, etc. Alternatively, the provisional correction value Me can be acquired, for example, using a mapping or checklist that at least sets the frequency offset Δf as a parameter.

[0138] In step 802, the object detection device 1 acquires the last correction value Mp. The last correction value Mp is the correction value M at the time when the last time the process of steps 801 to 804 was executed. Figure 1 The last correction value Mp is read out from the RAM or the nonvolatile rewritable memory by the CPU in the control section 5. In step 803, the object detection device 1 calculates the correction value difference AM. The correction value difference AM is the difference between the provisional correction value Me acquired or calculated in this time step 801 and the last correction value Mp. In step 804, the object detection device 1 determines whether the absolute value of the correction value difference AM is smaller than a prescribed value K. The prescribed value K is a positive number, and corresponds to the protection value with respect to the absolute value of the correction value M of the drive frequency.

[0139] In the case where the absolute value of the correction value difference AM is smaller than the prescribed value K (i.e., step 804 = Yes), the object detection device 1 executes the process of step 805, and then ends the correction process of the main drive frequency. In step 805, the object detection device 1 sets the provisional correction value Me as the correction value M this time. The correction value set is stored in the RAM or the nonvolatile rewritable memory in time series at prescribed times.

[0140] In the case where the absolute value of the correction value difference AM is the prescribed value K or more (i.e., step 804 = No), the object detection device 1 executes the process of step 806, and then ends the correction process of the main drive frequency. In step 806, the object detection device 1 sets the value obtained by dividing the product of the prescribed value K and the provisional correction value Me by the absolute value of the provisional correction value Me, and adding the value to the last correction value Mp, as the correction value M this time. Thus, the correction value M this time is protected by K or -K. The correction value M set is stored in the RAM or the nonvolatile rewritable memory in time series at prescribed times.

[0141] In the case where the absolute value of the correction value difference AM is the prescribed value K or more (i.e., step 804 = No), the object detection device 1 executes the process of step 806, and then ends the correction process of the main drive frequency. In step 806, the object detection device 1 sets the value obtained by dividing the product of the prescribed value K and the provisional correction value Me by the absolute value of the provisional correction value Me, and adding the value to the last correction value Mp, as the correction value M this time. Thus, the correction value M this time is protected by K or -K. The correction value M set is stored in the RAM or the nonvolatile rewritable memory in time series at prescribed times.

[0142] (Modified Examples)

[0143] The present disclosure is not limited to the above-described embodiments. Therefore, the above-described embodiments can be appropriately changed. Hereinafter, representative modified examples will be described. In the description of the following modified examples, mainly the points different from the above-described embodiments will be described. In addition, in the above-described embodiments and the modified examples, the same reference numerals are attached to the parts that are the same or equivalent to each other. Therefore, in the description of the following modified examples, as for the constituent elements having the same reference numerals as those of the above-described embodiments, the description in the above-described embodiments can be appropriately referred to, as long as there is no technical contradiction or special additional description.

[0144] The present disclosure is not limited to the specific device structure shown in the above-described embodiment. For example, the object detection device 1 is not limited to a vehicle-mounted structure, i.e., a structure mounted on the vehicle V. Thus, specifically, for example, the object detection device 1 can also be mounted on a ship or a flying body.

[0145] The object detection device 1 is not limited to Figure 5A the structure shown in which one transceiver 2 and one drive signal generation section 3 are provided respectively. That is, the object detection device 1 can also be provided with a plurality of transceivers 2. In this case, the drive signal generation section 3 can be provided in the same number as the transceivers 2.

[0146] At least any one of the capacitor C3, the resistor R2, and the inductor LT of the constituent elements of the parallel resonance circuit RCp can be omitted in the secondary-side winding of the transformer. Specifically, for example, in a case where the parallel resonance can be formed by the capacitance C2 in the transducer 21 and the inductance LT of the secondary-side winding of the transformer, the capacitor C3 can not exist. In a case of a structure driven by an inverter, the transformer is not needed. The resistor R3 is sometimes provided in a structure in which high sensitivity is intended to be obtained in the main measurement, but the present disclosure is effective even in this case.

[0147] The electromechanical energy conversion element provided in the transducer 21 is not limited to a piezoelectric element. That is, for example, as the electromechanical energy conversion element described above, a capacitive element can be used.

[0148] The two-dimensional position of the object B with respect to the host vehicle can sometimes be detected by triangulation using a plurality of transducers 21. In this case, for example, a transmission wave having the same frequency characteristic, i.e., code can be transmitted from each of a plurality of transducers 21 mounted on the host vehicle. At this time, the "regular wave" becomes a reception wave in a case where a reflection wave of the transmission wave transmitted from the host vehicle is received by the host vehicle. In contrast, the "irregular wave" becomes a reception wave in a case where a reflection wave of the transmission wave transmitted from another vehicle is received by the host vehicle. Thereby, it is possible to well suppress the influence caused by interference between a plurality of vehicles.

[0149] Alternatively, for example, a transmission wave arranged with different frequency characteristics, i.e., codes can be transmitted from each of a plurality of transducers 21 mounted on the host vehicle. Thereby, it is easy to strictly distinguish between the direct wave common to both the transmission-side transducer 21 and the reception-side transducer 21 and the indirect wave different from each other, and thus it is possible to well suppress misrecognition caused by the influence of multiple reflections and the like.

[0150] The object detection device 1 is not limited to the structure in which the transceiver 2, the drive signal generation section 3, the reception signal processing section 4, and the control section 5 are supported by one sensor housing. For example, all or at least a part of each functional structure provided in the drive signal generation section 3, the reception signal processing section 4, and the control section 5 can be provided outside the sensor housing in the ultrasonic sensor.

[0151] Some of the components of the drive signal generation section 3, the reception signal processing section 4, and the control section 5 can be provided in the above-described external device. Specifically, for example, some of the transmission control section 51 to the reception determination section 59 can be provided in the external device.

[0152] The drive signal generation section 3 and / or the reception signal processing section 4 can be provided in the control section 5. Specifically, for example, the amplitude signal generation section 42 and the amplitude signal acquisition section 54 can be integrated. Alternatively, the frequency signal generation section 43 and the frequency signal acquisition section 55 can be integrated.

[0153] In the present embodiment, each functional structure and method described above is implemented by a special-purpose computer provided with a CPU or the like. The above-described special-purpose computer is provided by a processor programmed to execute one or more functions and a memory that embody the functions using a computer program. However, the present disclosure is not limited to the above-described manner. That is, the control section 5 is not limited to a known microcomputer provided with a CPU or the like.

[0154] Specifically, for example, each functional structure and method described above can be implemented by a special-purpose computer provided by a processor constituted by one or more special-purpose hardware logic circuits. Alternatively, each functional structure and method described above can be implemented by one or more special-purpose computers constituted by a combination of a processor programmed to execute one or more functions and a memory and a processor constituted by one or more hardware logic circuits. That is, all or a part of the control section 5 can be an ASIC or an FPGA constituted so as to be able to implement the above-described functions, such as a gate array or the like. The ASIC is an abbreviation for Application Specific Integrated Circuit. The FPGA is an abbreviation for Field Programmable Gate Array.

[0155] In addition, the computer program can be stored in a non-transitory tangible storage medium that is readable by a computer as instructions executed by the computer. That is, the device or method according to the present disclosure can be embodied as a computer program including steps for implementing each function or method described above or a non-transitory tangible storage medium storing the program.

[0156] In the above-described embodiment, the functional configuration elements constituting the features of the present disclosure are provided in the control section 5. Therefore, the device related to the present disclosure can be evaluated as the control section 5 as an object detection control device. However, the present disclosure is not limited to the above-described mode. That is, for example, the device related to the present disclosure can also be evaluated as the object detection device 1 including the transceiver 2 and the like. Or, for example, in a case where a part of the transmission control section 51 to the reception determination section 59 is provided to an external device, the device related to the present disclosure can also be evaluated as the object detection device 1 and / or the external device.

[0157] The present disclosure is not limited to the specific operation mode and processing mode shown in the above-described embodiment. For example, in the above-described specific example, the prediction measurement is performed every time the object detection condition is established in one trip. However, the present disclosure is not limited to the above-described mode. That is, for example, the prediction measurement can be performed once in one trip. Specifically, for example, if the prediction measurement is performed at the time when the object detection condition is established for the first time in one trip, the prediction measurement can not be performed during the period until the ignition switch is turned off thereafter.

[0158] The code or code arrangement in the drive signal is not particularly limited. That is, for example, in a case where the up chirp is set to "1", the CW is set to "0", and the down chirp is set to "-1", a code including at least either one of "1" and "-1" for one bit or more can be given in the drive signal. Specifically, for example, the code arrangement of "1, 0", "-1, 0", "1, 1, 0", "1, 0, -1", "1, 1, 0, -1", and the like can be applied. In addition, as the up chirp and the down chirp, a so-called V-shaped chirp can also be used. Furthermore, the code or code arrangement in the drive signal can be changeable or unchangeable.

[0159] The more complex the code or code arrangement is in order to improve the recognition accuracy, the more the recognition accuracy is worried to be reduced due to the change in the transmission frequency caused by the attachment of foreign matter or the like. In addition, as described above, in the existing reverberation frequency measurement technology, it is difficult to perform the measurement of the reverberation frequency with high accuracy due to the influence of the parallel resonant circuit RCp. In this point, according to the present disclosure, based on the result of the reverberation frequency measurement with high accuracy and stability, the drive frequency, that is, the transmission frequency can be well corrected. Therefore, according to the present disclosure, the recognition accuracy can be more reliably improved by complicating the code or code arrangement.

[0160] The switching of the transmission / reception characteristics between the pre-drive and the pre-measurement and the main drive and the main measurement can be performed only according to the transmission characteristics, or only according to the reception characteristics. Or, the above-described switching can be performed only according to either one of the transmission control section 51 and the circuit characteristic setting section 52. In a case where the above-described switching is performed only according to the transmission control section 51, the circuit characteristic setting section 52 can be omitted.

[0161] At the pre-drive, instead of the low number of pulses, or together with it, at least one of the following can be used.

[0162] M1: Shift the drive frequency from the resonance frequency of the transceiver 2.

[0163] M2: Reduce the drive current compared to the main drive.

[0164] M3: Reduce the drive voltage compared to the main drive.

[0165] M4: Reduce the duty cycle compared to the main drive.

[0166] M5: Turn on the switch SW.

[0167] In the case of M1 described above, the drive frequency at the pre-drive is set to a value far from the middle value in the prescribed transceiving frequency band. Specifically, for example, the drive frequency described above can be set to a value near the upper limit value or the lower limit value in the transceiving frequency band. Further, the "prescribed transceiving frequency band" is a range of Si = 0 ~ Sib [dB] when Si = 0 [dB] at the resonance frequency f0 with the output or the sensitivity set to Si. Sib is typically, for example, -3 [dB]. The sensitivity is the sensitivity when the transducer 21 is used as a receiver. Further, such a transceiving frequency band can also be referred to as a "resonance band", a "-3 dB band", or a "3 dB band".

[0168] As in M5 described above, the circuit characteristic setting section 52 can turn on the switch SW not only at the pre-measurement but also at the pre-drive. Thereby, the output of the drive signal in the pre-drive can be suppressed to the extent necessary for the reverberation signal analysis, while suppressing the reception of the useless reflected wave.

[0169] As long as the purpose of measuring the reverberation frequency with high accuracy is achieved, it is not necessarily required to implement the pre-measurement. That is, in a manner in which the reverberation frequency is measured during the reverberation generation period after the drive in the main measurement without implementing the pre-measurement, the effect of improving the measurement accuracy can also be obtained by the present disclosure. Specifically, for example, the switch SW is turned on in the reverberation frequency measurement interval, and thereby the reverberation frequency can be measured with high accuracy.

[0170] The circuit characteristic changed by the circuit characteristic setting section 52 is not limited to the resistance component. That is, for example, instead of the resistance component, or together with it, the capacitance component and / or the inductance component can also be changed.

[0171] For example, as a method of changing the characteristic of the parallel resonance circuit RCp, there is also a method of cutting the transformer secondary side winding or the capacitor C3 corresponding to the inductance LT by the switch. By cutting the transformer secondary side winding or the capacitor C3 corresponding to the inductance LT, the parallel resonance frequency deviates, and thereby the effect of reducing the difference frequency is obtained.

[0172] The method of calculating the amount of deviation of the resonance frequency in the transceiver 2 is not limited to the above-described specific example. That is, for example, the frequency deviation Δf can be calculated based on the reverberation frequency deviation Δfr. The reverberation frequency deviation Δfr is the difference between the measured reverberation frequency fr and the reference value fr_ref. Specifically, the frequency deviation Δf can be calculated using the reverberation frequency deviation Δfr and a prescribed formula, for example. Alternatively, the frequency deviation Δf can be acquired using a map or a check table in which the reverberation frequency deviation Δfr is set as a parameter, for example. Alternatively, instead of the frequency deviation Δf, the frequency change rate Rf can be used. In this case, if explained according to the above-described specific example, the frequency change rate Rf can be calculated from Rf = fr / fr_ref using the measured reverberation frequency fr and the reference value fr_ref.

[0173] The correction value M of the drive signal is not limited to being calculated by the difference between the provisional correction value Me and the last correction value Mp. Specifically, for example, in the case where the above-described frequency change rate Rf is used, the correction value M can also be the ratio of the provisional correction value Me to the last correction value Mp. In this case, the corrected drive signal is calculated by multiplying or dividing the drive signal by the correction value M. That is, the correction value M is not limited to being calculated by the difference between the measured value fr of the reverberation frequency and the reference frequency fr_ref. Specifically, the correction value M can also be calculated by the ratio of the measured value fr of the reverberation frequency to the reference frequency fr_ref.

[0174] The correction value M of the drive signal is not limited to being calculated by comparison with the last correction value Mp. Specifically, comparison with an initial value that is normally measured can also be made.

[0175] The method of limiting, that is, protecting, the correction value M is also not limited to the above-described specific example. That is, for example, an upper limit value and a lower limit value can be set in the correction value M. In the upper limit value and the lower limit value of the correction value M, the absolute values can be the same or different.

[0176] In addition, for example, the correction value M can also be limited based on the ratio to the last correction value Mp. Specifically, for example, set to Me = Rf · Rc. Rc is a value corresponding to temperature correction or the like. In addition, set to the correction value ratio RMe = Me / Mp. In this case, if RMe < KL, set to the correction value M = KL · Mp. On the other hand, if RMe > KH, set to the correction value M = KH · Mp. In addition, if KL ≤ RMe ≤ KH, set to the correction value M = Me. Alternatively, for example, the correction value M can also be calculated from the result of moving average of the measured value fr of the reverberation frequency from the past history, whereby the effect of limiting the correction value M can be obtained.

[0177] In the above-described embodiments, the specific-interval detecting section 57 detects the generation interval as the specific interval. Thus, the non-generation interval can be determined. Therefore, the specific-interval detecting section 57 can be evaluated as indirectly detecting the non-generation interval as the second specific interval different from the first specific interval by directly detecting the generation interval as the first specific interval. Specifically, in the example of FIG. 10, the specific-interval detecting section 57 can be evaluated as also detecting the first non-generation interval Tnl and the second non-generation interval Tn2 by detecting the first generation interval Tgl and the second generation interval Tg2. Figure 9

[0178] However, the present disclosure is not limited to the above-described manner. That is, for example, the specific-interval detecting section 57 can also directly detect the non-generation interval as the specific interval. Specifically, the specific-interval detecting section 57 can also detect the flat portion as the specific interval based on the amplitude signal corresponding to the amplitude of the reverberation signal.

[0179] Figure 9 One example of a method of detecting the flat interval Ts corresponding to the flat portion is shown in FIG. 9. Further, Figure 9 The amplitude signal and the frequency signal of the received signal acquired in the state where the switch SW is on are shown in FIG. 10. In Figure 9 In FIG. 10, THs represents a flat determination threshold value for detecting the flat interval Ts. In this example, in order to make the amplitude convergence determination further more reliable, the flat determination threshold value THs is set to a value lower than the reverberation time determination threshold value THr.

[0180] If referring to Figure 10 , the specific-interval detecting section 57 detects a prescribed time interval in which the flat reference time Tsr is set as the end time as the flat interval Ts. The flat reference time Tsr is a time at which the amplitude signal decreases to the flat determination threshold value THs after the start time of the reverberation time Trev determined in a time interval of tracing back a prescribed time from the reference time Tr. Further, it is also possible to set the reverberation time determination threshold value THr on the low threshold value side so that the reverberation time determination threshold value THr and the flat determination threshold value THs become the same value. Further, in order to perform the abnormality determination, the reverberation time is used together with the frequency information.

[0181] Figure 10 Another example of a method of detecting the flat interval Ts is shown in FIG. 11. Further, Figure 9 The amplitude signal and the frequency signal of the received signal acquired in the state where the switch SW is off are shown in FIG. 12. According to Figure 10 and Figure 10 , the effects of alleviation of the difference frequency and improvement of the measurement accuracy of the reverberation frequency achieved by turning on the switch SW can be read.

[0182] In addition, in Figure 5A ​In the above, σ denotes the mean square error of the reverberation frequency. σth is a threshold for detecting the flat section Ts. The specific section detecting section 57 detects, as the flat section Ts, a section in which the frequency waveform whose mean square error σ of the reverberation frequency is smaller than the threshold σth is less disordered within the reverberation time.

[0183] The method of detecting the flat section Ts is not limited to the above-described examples. That is, for example, the flat section Ts can be detected based on the matching result of the amplitude signal waveform and the reference waveform for detecting the flat section. The reference waveform can also use the waveform measured at the normal time. Alternatively, the reference waveform can be a waveform derived by calculation from the circuit characteristics of the microphone and the circuit.

[0184] The measurement section setting section 58 can set the entire one non-generation section as the measurement section, or can set a part thereof as the measurement section. That is, for example, if the second non-generation section Tn2 is divided into two, the measurement section setting section 58 can set only the latter half of the flat section as the measurement section Tz. Figure 6 to Figure 8

[0185] The measurement of the reverberation frequency is performed multiple times, and statistical processing is performed, whereby the measurement accuracy of the reverberation frequency is further improved. As the statistical processing, for example, an average value calculation, a weighted average value calculation, a median extraction, a blunting process, or the like can be used. In the statistical processing, an exclusion process of a prescribed abnormal value or an "outlier" can also be applied.

[0186] Conceptually similar expressions of "acquire", "detect", "calculate", "operate", "infer", and the like can be replaced with each other as long as no technical contradiction is caused. In addition, the inequality signs in each determination process can have or not have equality signs. That is, for example, "equal to or greater than the threshold value" can be changed to "greater than the threshold value". Similarly, "equal to or less than the threshold value" can be changed to "less than the threshold value".

[0187] The components constituting the above-described embodiments are not necessarily essential except for cases where it is particularly indicated that they are essential and cases where it is clearly recognized as essential in principle. In addition, in cases where a numerical value is mentioned regarding the number, quantity, range, or the like of the components, the present disclosure is not limited to the specific numerical value except for cases where it is particularly indicated that it is essential and cases where it is clearly limited to the specific numerical value in principle. Similarly, in cases where the shape, direction, positional relationship, or the like of the components is mentioned, the present disclosure is not limited to the shape, direction, positional relationship, or the like except for cases where it is particularly indicated that it is essential and cases where it is limited to the specific shape, direction, positional relationship, or the like in principle.

[0188] The modified examples are not limited to the above-described examples. In addition, a plurality of modified examples can be combined with each other. Furthermore, all or a part of the above-described embodiments and all or a part of the modified examples can be combined with each other.​

[0189] (method, program)

[0190] The steps or processes that constitute the object detection method according to the present disclosure correspond to the steps or processes shown in the flowcharts of the above-described embodiments, modifications, and Figure 6 to Figure 8 the flowcharts of the above-described embodiments, modifications, and ​ the flowcharts of the above-described embodiments, modifications, and

[0191] Thus, the present disclosure represented by the above-described embodiments and modifications includes the following aspects with respect to the method and the program. Furthermore, the aspects described below can be applied in combination with each other as long as they are not technically contradictory.

[0192] According to a first aspect, an object detection method that detects an object (B) around a moving body (V) includes the following process. Furthermore, an object detection program includes the following process executed by an object detection device (1) configured to detect an object (B) around a moving body (V) by being mounted on the moving body. Moreover, the "process" can be referred to as a "step", a "procedure", or an "action".

[0193] The process includes:

[0194] setting a transmission characteristic and / or a reception characteristic in a transceiver (2) that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including an object-based reflection wave of the transmission wave;

[0195] measuring a frequency of a reverberation signal generated in the transceiver, that is, a reverberation frequency;

[0196] detecting an object based on the reception wave,

[0197] In the process of setting the transmission characteristic and / or the reception characteristic, the transmission characteristic and / or the reception characteristic is reduced when measuring the reverberation frequency than when detecting the object.

[0198] According to a second aspect, the process of setting the transmission characteristic and / or the reception characteristic includes the following process: reducing the sound pressure when measuring the reverberation frequency than when detecting the object.

[0199] According to a third aspect,

[0200] The process of setting the transmission characteristic and / or the reception characteristic includes the following process: controlling transmission of the transmission wave in the transceiver such that the transmission wave is subjected to frequency modulation when detecting the object, and on the other hand, the transmission wave is not subjected to frequency modulation when measuring the reverberation frequency,

[0201] When detecting the object, a code corresponding to a frequency modulation pattern in the reception wave is determined.

[0202] According to a fourth aspect, the process of setting the transmission characteristic and / or the reception characteristic includes a process of setting the transceiver to different circuit characteristics at the time of detecting the object and at the time of measuring the reverberation frequency.

[0203] According to a fifth aspect,

[0204] The transceiver includes a transducer (21) having an electromechanical conversion function, a transceiving circuit (22) electrically connected to the transducer,

[0205] The transceiving circuit has a capacitor (C3) and resistors (R2, R3) that constitute a parallel resonance circuit (RC2) by being connected in parallel with the transducer,

[0206] The process of setting the transmission characteristic and / or the reception characteristic includes a process of setting the parallel connection state of the resistors to be different at the time of detecting the object and at the time of measuring the reverberation frequency.

[0207] According to a sixth aspect, in the process of setting the transmission characteristic and / or the reception characteristic, a drive frequency of the transceiver is corrected based on a measurement result of the reverberation frequency.

[0208] According to a seventh aspect, in the process of correcting the drive frequency, a correction value of the drive frequency decided based on the measurement result is set to be within a prescribed range.

Claims

1. An object detection device configured to detect an object around a moving body by being mounted on the moving body, wherein The object detection device includes: a reverberation measuring section that measures a frequency of a reverberation signal generated in a transceiver that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including a reflection wave based on the object, an object detecting section that detects the object based on the reception wave, and a characteristic setting section that sets a transmission characteristic and / or a reception characteristic in the transceiver, the characteristic setting section is a transmission control section that sets the transmission characteristic of the transmission wave and / or a circuit characteristic setting section that sets a circuit characteristic in the transceiver, and the transmission characteristic and / or the reception characteristic are reduced when the reverberation frequency is measured by the reverberation measuring section than when the object is detected by the object detecting section.

2. The object detection device according to claim 1, wherein the transmission control section reduces a sound pressure of the transmission wave when the reverberation frequency is measured by the reverberation measuring section than when the object is detected by the object detecting section.

3. The object detection device according to claim 2, wherein a code determining section that determines a code corresponding to a frequency modulation method in the reception wave is further included, the transmission control section controls transmission of the transmission wave in the transceiver so that the transmission wave is frequency-modulated when the object is detected by the object detecting section and is not frequency-modulated when the reverberation frequency is measured by the reverberation measuring section.

4. The object detection device according to any one of claims 1 to 3, wherein the circuit characteristic setting section sets the transceiver to different circuit characteristics when the object is detected by the object detecting section and when the reverberation frequency is measured by the reverberation measuring section.

5. The object detection device according to claim 4, wherein the transceiver includes a transducer having an electromechanical conversion function and a transceiving circuit electrically connected to the transducer, the transceiving circuit has a capacitor and a resistor that constitute a parallel resonant circuit by being connected in parallel to the transducer, the circuit characteristic setting section sets the parallel connection state of the resistor to be different when the object is detected by the object detecting section and when the reverberation frequency is measured by the reverberation measuring section.

6. The object detection device according to any one of claims 1 to 3, wherein the transmission control section corrects a drive frequency of the transceiver based on a measurement result of the reverberation frequency by the reverberation measuring section.

7. The object detection device according to claim 6, wherein the transmission control section sets a correction value of the drive frequency decided based on the measurement result to be within a prescribed range.

8. An object detection method of detecting an object in the surroundings of a moving body, wherein a transmission characteristic and / or a reception characteristic in a transceiver that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including a reflection wave based on the object are set, a frequency of a reverberation signal generated in the transceiver, that is, a reverberation frequency, is measured, the object is detected based on the reception wave, and the transmission characteristic and / or the reception characteristic are reduced when the reverberation frequency is measured than when the object is detected. In the setting of the transmission characteristic and / or the reception characteristic, the transmission characteristic and / or the reception characteristic is reduced at the time of measuring the reverberation frequency, compared to the time of detecting the object.

9. The object detection method according to claim 8, wherein In the setting of the transmission characteristic and / or the reception characteristic, the sound pressure of the transmission wave is reduced at the time of measuring the reverberation frequency, compared to the time of detecting the object.

10. The object detection method according to claim 9, wherein In the setting of the transmission characteristic and / or the reception characteristic, the transmission of the transmission wave in the transceiver is controlled so that the transmission wave is subjected to frequency modulation at the time of detecting the object, and is not subjected to frequency modulation at the time of measuring the reverberation frequency. At the time of detecting the object, a code corresponding to the frequency modulation mode in the reception wave is determined.

11. The object detection method according to any one of claims 8 to 10, wherein In the setting of the transmission characteristic and / or the reception characteristic, the transceiver is set to different circuit characteristics at the time of detecting the object and at the time of measuring the reverberation frequency.

12. The object detection method according to claim 11, wherein The transceiver includes a transducer having an electromechanical conversion function, and a transceiving circuit electrically connected to the transducer, The transceiving circuit has a capacitor and a resistor configured to constitute a parallel resonance circuit by being connected in parallel to the transducer, In the setting of the transmission characteristic and / or the reception characteristic, the parallel connection state of the resistor is set to be different at the time of detecting the object and at the time of measuring the reverberation frequency.

13. The object detection method according to any one of claims 8 to 10, wherein In the setting of the transmission characteristic and / or the reception characteristic, the drive frequency of the transceiver is corrected on the basis of the measurement result of the reverberation frequency.

14. The object detection method according to claim 13, wherein In the correction of the drive frequency, an absolute value of a correction value of the drive frequency decided on the basis of the measurement result is set to be equal to or less than a prescribed value.

15. An object detection program product, which is an object detection program product executed by an object detection device configured to detect an object around a mobile body by being mounted on the mobile body, wherein The process executed by the object detection device includes: setting a transmission characteristic and / or a reception characteristic in a transceiver that transmits a transmission wave as an ultrasonic wave to the outside and receives a reception wave including a reflection wave of the transmission wave based on the object; measuring a frequency of a reverberation signal generated in the transceiver, that is, a reverberation frequency; detecting the object on the basis of the reception wave, In the process of setting the transmission characteristic and / or the reception characteristic, the transmission characteristic and / or the reception characteristic is reduced at the time of measuring the reverberation frequency, compared to the time of detecting the object.

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