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

Abstract

An object detection device (1) configured to detect an object (B) around a moving body (V) by being mounted on the moving body comprises a reverberation measurement unit (591), a specific interval detection unit (57), and a measurement interval setting unit (58). The reverberation measurement unit measures the reverberation frequency, which is the frequency of a reverberation signal generated by a transceiver (2) that transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave based on a reflection wave of an object including the transmission wave. The specific interval detection unit detects a specific interval, which is a generation interval in which the generation of beats caused by a plurality of reverberation frequency components is confirmed in the reverberation signal, or a non-generation interval in which the generation of such beats is hardly confirmed. The measurement interval setting unit sets a measurement interval in which the reverberation measurement unit measures the reverberation frequency in the non-generation interval based on the detection result of the specific interval.

Description

Technical Field

[0001] The present disclosure relates to an object detection device and an object detection method for detecting an object around a moving object, and also to an object detection program executed by such an object detection device. Background Art

[0002] Patent document 1 discloses an example of ultrasonic sonar. The ultrasonic sonar transmits ultrasonic waves from an ultrasonic transducer and receives the ultrasonic waves reflected by an obstacle to detect obstacles. The ultrasonic sonar described in Patent document 1 detects abnormalities based on the results of reverberation time and frequency analysis after the ultrasonic transmission stops.

[0003] Patent Document 1: Japanese Patent No. 4267161

[0004] Analysis of the reverberation signal, that is, measurement of the reverberation frequency, can be used for detection of abnormalities including adhesion of foreign matter such as mud, correction of the transmission frequency, etc. Therefore, it is required to analyze the reverberation signal as accurately as possible. Summary of the invention

[0005] The present disclosure has been made in view of the above-mentioned circumstances, etc. That is, the present disclosure provides, for example, a device configuration, a method, and a program that can analyze a reverberation signal with as high accuracy as possible.

[0006] The object detection device is mounted on a moving body and is configured to detect objects around the moving body.

[0007] According to one aspect of the present disclosure, an object detection device comprises:

[0008] a reverberation measuring unit for measuring a reverberation frequency, which is a frequency of a reverberation signal generated by a transceiver for transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflection wave of the transmission wave reflected by the object;

[0009] a specific section detecting unit that detects a specific section, the specific section being a generation section in which generation of beats caused by a plurality of reverberation frequency components is confirmed in the reverberation signal, or a non-generation section in which generation of such beats is hardly confirmed; and

[0010] The measurement section setting unit sets a measurement section for measuring the reverberation frequency by the reverberation measuring unit in the non-generation section based on the detection result of the specific section.

[0011] According to another aspect of the present disclosure, an object detection method is an object detection method for detecting objects around a moving body, comprising the following processing or sequence, namely:

[0012] detecting a specific interval, the specific interval being a generation interval in which generation of beats caused by a plurality of reverberation frequency components is confirmed in a reverberation signal generated by a transceiver, or a non-generation interval in which generation of such beats is hardly confirmed, the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflected wave resulting from the transmission wave being reflected by the object;

[0013] Based on the detection result of the specific interval, a measurement interval for measuring the frequency of the reverberation signal, that is, the reverberation frequency, is set in the non-generation interval; and

[0014] In the set measurement interval, the reverberation frequency is measured.

[0015] According to another aspect of the present disclosure, the object detection program is a program executed by an object detection device configured to be mounted on a moving body and detect objects around the moving body.

[0016] The processing performed by the object detection device includes:

[0017] a process of detecting a specific interval, the specific interval being a generation interval in which generation of beats caused by a plurality of reverberation frequency components is confirmed in a reverberation signal generated by a transceiver, or a non-generation interval in which generation of such beats is hardly confirmed, the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflected wave resulting from the transmission wave being reflected by the object;

[0018] Based on the detection result of the specific interval, a measurement interval for measuring the frequency of the reverberation signal, that is, the reverberation frequency is set in the non-generation interval; and

[0019] The reverberation frequency is measured in the set measurement interval.

[0020] In addition, in each column of the application, there are cases where reference figures in brackets are added to each element. However, such reference figures are only an example of the correspondence between the element and the specific unit described in the embodiment described later. Therefore, the present disclosure is not limited in any way by the description of the above-mentioned reference figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a block diagram showing a schematic configuration of an object detection device according to an embodiment.

[0022] Figure 2 Yes means Figure 1 A schematic circuit diagram showing an equivalent circuit configuration of a portion of a transceiver is shown.

[0023] Figure 3 Yes means Figure 1A timing diagram of an operation example of the object detection device shown.

[0024] Figure 4A It means in Figure 2 Graph of frequency characteristics when the switch SW is turned on in the circuit diagram shown.

[0025] Figure 4B It means in Figure 2 Graph of frequency characteristics when the switch SW is turned off in the circuit diagram shown.

[0026] Figure 5A Yes means Figure 1 FIG. 1 is a timing chart schematically showing an example of the reverberation frequency measurement operation of the object detection device shown.

[0027] Figure 5B Is magnification Figure 5A A portion of the timing diagram is shown.

[0028] Figure 6 Yes means Figure 1 A flowchart of an operation example of the object detection device shown.

[0029] Figure 7 Yes means Figure 6 A flow chart of one example of a frequency shift calculation process is shown.

[0030] Figure 8 Yes means Figure 6 FIG. 1 is a flowchart showing an example of the main drive frequency correction process.

[0031] Fig. 9 Yes means Figure 1 FIG. 1 is a timing chart schematically showing another example of the reverberation frequency measurement operation of the object detection device shown.

[0032] Fig.10 Yes means Figure 1 FIG. 1 is a timing chart schematically showing another example of the reverberation frequency measurement operation of the object detection device shown. DETAILED DESCRIPTION

[0033] (Implementation Method)

[0034] The following describes the embodiments of the present disclosure based on the accompanying drawings. In addition, if various modifications that can be applied to an embodiment are inserted in the middle of a series of descriptions related to the embodiment, there is a concern that it will hinder the understanding of the embodiment. Therefore, the modifications are collectively recorded after the description of the embodiment.

[0035] (constitute)

[0036] If you refer to Figure 1, the object detection device 1 is configured to detect an object B around the vehicle V, that is, outside the vehicle V, by being mounted on the vehicle V as a moving body. Hereinafter, the state in which the object detection device 1 is mounted on the vehicle V is referred to as the "vehicle-mounted state". In addition, the vehicle V in which the object detection device 1 of the present embodiment is mounted is referred to as the "host vehicle" hereinafter.

[0037] The object detection device 1 has a structure as a so-called ultrasonic sensor. Specifically, the object detection device 1 is configured to detect surrounding objects B and obtain distance measurement information corresponding to the object B by transmitting and receiving ultrasonic waves. The object detection device 1 is connected to an external device such as an obstacle detection ECU (not shown) in the vehicle that controls various actions such as object detection actions and reports accompanying the actions via an on-board network line in a manner that enables information communication. ECU is an abbreviation for Electronic Control Unit.

[0038] The object detection device 1 includes a transceiver 2, a drive signal generator 3, a reception signal processor 4, and a control unit 5. The object detection device 1 has a structure in which the transceiver 2, the drive signal generator 3, the reception signal processor 4, and the control unit 5 are accommodated and supported by a sensor housing.

[0039] The transceiver 2 is configured to transmit a transmission wave as an ultrasonic wave toward the outside, and receive a reflected wave when the transmission wave is reflected by the object B. In the present embodiment, the object detection device 1 has a transceiver integrated structure. That is, the object detection device 1 is configured to include one transceiver 2, and the transceiver 2 performs the transceiver function.

[0040] The transceiver 2 has a transducer 21 and a transceiver circuit 22. The transducer 21 having an electro-mechanical conversion function is configured as an ultrasonic microphone having an electro-mechanical energy conversion element built into a substantially cylindrical microphone housing. The transducer 21 outputs an ultrasonic transmission wave corresponding to an input electrical signal, and conversely outputs an electrical signal corresponding to an input ultrasonic reception wave. In the present embodiment, the transducer 21 has a piezoelectric element as an electro-mechanical energy conversion element. In the vehicle-mounted state, the transducer 21 is arranged at a position facing the outer surface of the vehicle, so that it is configured to be able to transmit a transmission wave to the outside of the vehicle and to be able to receive a reflected wave from the outside of the vehicle.

[0041] Specifically, when the transducer 21 is mounted on the vehicle, the transceiver surface 23 is installed on the outer panel component V1 so that the transceiver surface 23 is exposed to the external space of the vehicle from the through hole formed on the outer panel component V1 in the vehicle, that is, the mounting hole V2. The outer panel component V1 is, for example, a bumper or a body panel, and is formed of a plate made of synthetic resin or metal. The transceiver surface 23 is the outer surface of the above-mentioned microphone housing in the transducer 21, and is configured to function as a transmitting surface for transmitting waves and a receiving surface for receiving waves. In addition, the function and structure of the transducer 21 are already known or well-known at the time of filing this application. Therefore, in this specification, more detailed descriptions of the function and structure of the transducer 21 are omitted.

[0042] Each of the transceivers 2 includes a transducer 21 and a transceiver circuit 22. The transducer 21 is electrically connected to the transceiver circuit 22. The transceiver circuit 22 includes a digital / analog conversion circuit, an amplifier circuit, an analog / digital conversion circuit, and the like.

[0043] The transceiver circuit 22 is configured to drive the transducer 21 based on the input drive signal, so that the transducer 21 emits a transmission wave having 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 signal having a frequency within the ultrasonic frequency band. The frequency of the drive signal is hereinafter referred to as the "drive frequency".

[0044] In addition, the transceiver circuit 22 is configured to generate a received signal and output it to the received signal processing unit 4 by performing analog / digital conversion processing on the element output signal. The element output signal is an AC voltage signal generated and outputted by the transducer 21 through the vibration of the transceiver surface 23 when the transceiver surface 23 is excited by the reception of the received wave, etc. The "received signal" includes not only the reception of the received wave, but also the signal generated by the reverberation generated in the transceiver 2 after the drive signal is cut off. The received signal generated by the reverberation will be referred to as the "reverberation signal" hereinafter. In addition, the function and structure of the transceiver circuit 22 were already known or well-known at the time of filing the present application. Therefore, more detailed descriptions of the function and structure of the transceiver circuit 22 are omitted in this specification.

[0045] The drive signal generator 3 generates a drive signal based on a control signal received from the control unit 5 and outputs the drive signal to the transceiver 2, that is, the transceiver circuit 22. The control signal is a signal for controlling the output of the drive signal from the drive signal generator 3 to the transceiver 2.

[0046] The drive signal generating unit 3 is configured to generate and output a drive signal corresponding to the waveform pattern in a transmission wave encoded according to the waveform pattern. Specifically, the drive signal generating unit 3 is configured to selectively generate and output a chirped drive signal such that the transmission wave becomes a chirped wave, and a CW drive signal such that the transmission wave becomes a CW wave. A chirped wave is a wave whose frequency increases or decreases over time. A CW wave is a wave with a constant frequency. CW is the abbreviation of continuous waveform. CW waves are also called CF waves. CF is the abbreviation of continuous frequency. Chirped waves are a type of FM waves. FM is the abbreviation of frequency modulation.

[0047] The received signal processing unit 4 is configured to generate an amplitude signal and a frequency signal by performing various signal processing on the received signal. The amplitude signal is a signal corresponding to the amplitude of the received signal. The frequency signal is a signal corresponding to the frequency of the received signal. That is, the frequency signal is a signal corresponding to the waveform pattern related to the coding in the received signal. Specifically, the received signal processing unit 4 includes a filter processing unit 41, an amplitude signal generating unit 42, and a frequency signal generating unit 43.

[0048] The filter processing unit 41 is configured to perform a filter process for removing noise from a received signal. The amplitude signal generating unit 42 is configured to generate and output an amplitude signal based on the received signal after the filter processing by the filter processing unit 41. The frequency signal generating unit 43 is configured to generate and output a frequency signal based on the received signal after the filter processing by the filter processing unit 41.

[0049] In addition, the functions and structures of the filter processing unit 41, the amplitude signal generating unit 42, and the frequency signal generating unit 43 are already known or well-known at the time of filing the present application. Therefore, in this specification, more detailed descriptions of the functions and structures of the filter processing unit 41, the amplitude signal generating unit 42, and the frequency signal generating unit 43 are omitted.

[0050] The control unit 5 is configured to control the overall operation of the object detection device 1. Specifically, in the present embodiment, the control unit 5 is a well-known microcomputer having a CPU, a ROM, a non-volatile rewritable memory, a RAM, an input / output interface, and the like. CPU is the abbreviation of Central Processing Unit. ROM is the abbreviation of Read Only Memory. Examples of non-volatile rewritable memories include EPROM, EEPROM, flash memory, and magnetic recording media. EPROM is the abbreviation of Erasable Programmable Read Only Memory. EEPROM is the abbreviation of Electrically Erasable Programmable Read Only Memory. RAM is the abbreviation of Random access memory. ROM, non-volatile rewritable memory, and RAM are non-migrating physical storage media. ROM and / or non-volatile rewritable memory are equivalent to storage media storing the object detection program of the present embodiment.

[0051] The control unit 5 is configured to perform various processes by reading and executing a program stored in a ROM or a nonvolatile rewritable memory. Specifically, the control unit 5 is configured to control the transmission of the transmission wave in the transceiver 2 and detect the object B based on the reception wave received by the transceiver 2. That is, the control unit 5 has a configuration as an ECU built into the ultrasonic sensor.

[0052] The control unit 5 has the following functional elements as a functional configuration implemented on a microcomputer. That is, the control unit 5 has a transmission control unit 51, a circuit characteristic setting unit 52, a filter characteristic setting unit 53, an amplitude signal acquisition unit 54, a frequency signal acquisition unit 55, a delay correction unit 56, a specific section detection unit 57, a measurement section setting unit 58, and a reception determination unit 59.

[0053] The transmission control unit 51 is configured to control the transmission state of the transmission wave from the transceiver 2 by outputting a control signal to the drive signal generating unit 3. Specifically, the transmission control unit 51 sets the drive frequency, waveform mode, and output timing of the drive signal generated and output in the drive signal generating unit 3 through the control signal. In addition, the transmission control unit 51 sets the drive current and drive voltage through the control signal. The drive current and drive voltage are the current and voltage applied to the transducer 21.

[0054] The transmission control unit 51, which is a characteristic setting unit for setting the transmission characteristics and / or receiving characteristics in the transceiver 2, is configured to control or set the transmission characteristics of the transmission wave. That is, the transmission control unit 51 is configured to control the sound pressure of the transmission wave using transmission output characteristics such as the number of pulses, driving current, driving voltage, and duty cycle. In the present embodiment, the transmission control unit 51 sets different transmission output characteristics (for example, the number of pulses) in the main drive and the pre-drive. The main drive refers to the acquisition of ranging information for the detection of the object B, that is, the application or output of the driving signal to the transceiver 2 during the main measurement. The pre-drive refers to the application or output of the driving signal to the transceiver 2 during the reverberation frequency measurement before the main measurement, that is, the pre-measurement. The reverberation frequency is the frequency of the reverberation signal. In the following, in order to avoid redundancy in the description in the specification, the "transmission and reception characteristics" are used in the meaning of the transmission characteristics and / or the receiving characteristics in the present specification.

[0055] The transmission control unit 51 is configured to reduce the transmission characteristics during pre-driving compared to the main driving. Specifically, the transmission control unit 51 reduces the sound pressure of the transmission wave by using a lower number of pulses than during the main driving during pre-driving. In addition, the transmission control unit 51 controls the transmission of the transmission wave in the transceiver 2 in such a manner that the transmission wave is frequency modulated as a chirped wave during the main measurement, i.e., the main driving, and the transmission wave is not frequency modulated as a CW wave during the pre-measurement, i.e., the pre-driving.

[0056] The transmission control unit 51 is configured to correct the driving frequency based on the measurement result of the reverberation frequency of the transceiver 2. At this time, the transmission control unit 51 makes the correction value of the driving frequency determined based on the measurement result of the reverberation frequency within a predetermined range.

[0057] The circuit characteristic setting unit 52, which is a characteristic setting unit for setting the transmission and reception characteristics in the transceiver 2, is provided to set the circuit characteristics in the transceiver 2. In the present embodiment, the circuit characteristic setting unit 52 is configured to set different circuit characteristics in the reverberation frequency measurement based on the pre-drive, that is, the pre-measurement, and in the detection of the object B based on the main drive, that is, the main measurement. Specifically, the circuit characteristic setting unit 52 sets the parallel connection state of the resistor connected in parallel with the transducer 21 in the transceiver circuit 22 to different states in the pre-measurement and the main measurement. In addition, the circuit characteristic setting unit 52 is configured to lower the reception characteristics in the pre-drive compared to the main drive.

[0058] Figure 2 The portion of the transceiver circuit 22 that is connected to the transducer 21, that is, the secondary side portion is shown together with the equivalent circuit of the transducer 21. Figure 2In FIG. 1 , the inductance LT and the resistance RT correspond to the secondary winding of the transformer provided in the transceiver circuit 22. Illustration and description of the primary side portion of the transceiver circuit 22 including the primary winding of the transformer are omitted.

[0059] Capacitor C1, inductor L1, and resistor R1 show the mechanical vibration in transducer 21 as an equivalent circuit. A series resonant circuit RCs is formed by connecting capacitor C1, inductor L1, and resistor R1 in series. Capacitor C2 is a capacitance component in the piezoelectric element specified by the inter-electrode distance, electrode area, and dielectric constant of the piezoelectric element, and is connected in parallel with the series resonant circuit RCs in the equivalent circuit.

[0060] A parallel resonant circuit RCp is formed by the secondary winding of the transformer provided in the transceiver circuit 22, the capacitor C2, the capacitor C3, and the resistor R2 in the transducer 21. The capacitor C3 is connected in parallel with the transducer 21 to adjust the temperature characteristics in the transceiver 2 and the resonant frequency in the parallel resonant circuit RCp. The resistor R2 is connected in parallel with the transducer 21 and the capacitor C3 to adjust the reverberation time and the amplification factor.

[0061] In addition, a resistor R3 and a switch SW are provided in the parallel resonant circuit RCp. The resistor R3 is provided to function as an attenuator that reduces the amplification factor, and to achieve the adaptation of the reverberation frequency characteristics by reducing the Q value. The resistor R3 is connected in parallel with the transducer 21, the resistor 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 unit 5, that is, the circuit characteristic setting unit 52. The circuit characteristic setting unit 52 turns on the switch SW during the pre-measurement, and on the other hand, turns off the switch SW during the pre-drive, the main drive, and the main measurement.

[0062] Refer again Figure 1 The filter characteristic setting unit 53 is configured to set the filter frequency condition in the filter processing unit 41. That is, the filter characteristic setting unit 53 adjusts the frequency band of the signal passing through the filter processing unit 41 according to the change in the transmission frequency caused by the adhesion of foreign matter on the transmission and reception surface 23, etc. The "transmission frequency" is the frequency of the transmission wave. Specifically, the filter characteristic setting unit 53 adjusts such a frequency band based on the measurement result of the reverberation frequency.

[0063] The amplitude signal acquisition unit 54 is configured to acquire the amplitude signal from the amplitude signal generation unit 42. The frequency signal acquisition unit 55 is configured to acquire the frequency signal from the frequency signal generation unit 43. The delay correction unit 56 is configured to correct the delay time generated between the amplitude signal and the frequency signal.

[0064] The specific interval detection unit 57 is configured to detect a specific interval. The specific interval is a generation interval or a non-generation interval. The generation interval is a time interval in which the generation of beats caused by multiple reverberation frequency components is confirmed in the reverberation signal. The beat in the reverberation signal refers to a transition phenomenon caused by the offset of multiple reverberation frequency components, accompanied by a relatively large frequency change and / or a relatively large amplitude break. If the reverberation frequency is measured in such a generation interval, the measurement accuracy is greatly reduced. In contrast, the non-generation interval is a time interval in which the generation of such a beat is almost not confirmed. If the reverberation frequency is measured in such a non-generation interval, the measurement accuracy is good.

[0065] Therefore, in the present embodiment, the specific section detection unit 57 detects a reverberation break section in which a waveform break occurs in the amplitude signal corresponding to the amplitude of the reverberation signal as a generation section, i.e., a specific section. Specifically, the specific section detection unit 57 detects a portion of the time section before the lower end portion where the amplitude signal decreases in a convergent manner, where the amplitude signal is less than the reverberation break determination threshold value, as the generation section. In addition, the specific section detection unit 57 detects the specific section based on the correction result of the delay correction unit 56.

[0066] The measurement interval setting unit 58 is configured to set a measurement interval in the non-generation interval based on the detection result of the specific interval by the specific interval detection unit 57. In the present embodiment, the measurement interval is a time interval for measuring, i.e., calculating the reverberation frequency using the predicted measurement. Specifically, the measurement interval setting unit 58 determines the non-generation interval by removing the generation interval from the time interval in which the predicted measurement is performed. Then, the measurement interval setting unit 58 sets the measurement interval in the determined non-generation interval. In more detail, the measurement interval setting unit 58 sets the determined non-generation interval as the measurement interval.

[0067] The reception determination unit 59 is configured to perform various operations such as determination, diagnosis, and detection related to the reception signal based on the amplitude signal acquired by the amplitude signal acquisition unit 54 and the frequency signal acquired by the frequency signal acquisition unit 55. Specifically, the reception determination unit 59 includes a reverberation measurement unit 591, a diagnosis unit 592, a code determination unit 593, and an object detection unit 594.

[0068] The reverberation measurement unit 591 is configured to measure, i.e., calculate, the reverberation frequency in the measurement interval set by the measurement interval setting unit 58. The reception determination unit 59 delivers the measurement result of the reverberation frequency by the reverberation measurement unit 591 to the transmission control unit 51. In addition, the reception determination unit 59 delivers the measurement result of the reverberation frequency by the reverberation measurement unit 591 to the filter characteristic setting unit 53 so as to be used for the filter band adjustment performed by the filter characteristic setting unit 53.

[0069] The diagnosis unit 592 is configured to determine whether an abnormality has occurred in the transceiver 2 based on the amplitude signal and the frequency signal in the reverberation signal. That is, the diagnosis unit 592 determines the occurrence of disconnection, freezing, foreign matter adhesion, etc. based on the measurement result of the reverberation frequency of the reverberation measurement unit 591. Specifically, the diagnosis unit 592 determines that an abnormality has occurred in the transceiver 2 when the measurement result of the reverberation frequency is outside the normal range set in advance by measurement or the like. Moreover, when the diagnosis unit 592 determines that an abnormality has occurred in the transceiver 2, the abnormality is classified into any one of a foreign matter adhesion state, a freezing state, and a disconnection state according to the deviation from the normal range, and the classification result is output. In addition, for such abnormality determination based on the analysis result of the reverberation signal, for example, an abnormality determination that is already known or well-known at the time of filing this application can be used. Therefore, the detailed description of the abnormality determination is omitted in this specification.

[0070] The code determination unit 593 is configured to determine the code corresponding to the frequency modulation method in the received wave. Specifically, the code determination unit 593 determines whether the received wave is a regular wave based on the frequency signal acquired by the frequency signal acquisition unit 55 and a predetermined reference signal stored in advance. A "regular wave" is a received wave when the transceiver 2 receives a reflected wave of a transmission wave sent by itself. In contrast, the received wave caused by a transmission wave from other devices will be referred to as an "irregular wave" below. The "other devices" also include other transceivers 2 mounted on the vehicle. Specifically, the code determination unit 593 determines whether the received wave is a regular wave by performing pattern matching between the waveform of the frequency signal and the waveform of the reference signal.

[0071] The object detection unit 594 is configured to detect the object B based on the received wave, that is, the received signal. That is, the object detection unit 594 is configured to detect the object B based on the code determination result of the code determination unit 593. Specifically, when the received wave is a normal wave, the object detection unit 594 detects the existence 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 unit 54.

[0072] (Action Summary)

[0073] Hereinafter, the object detection device 1 of the present embodiment, and the object detection method and object detection program executed by the device are simply referred to as “the present embodiment.” Hereinafter, an outline of the operation of the present embodiment will be described together with the effects achieved by the present embodiment with reference to the drawings.

[0074] If the specified object detection conditions are met, the object detection device 1 starts the object detection operation. The object detection conditions include, for example, that the vehicle's travel speed is within a specified range, that the vehicle's gear is in a travel gear that includes reverse travel, etc. If the object detection conditions are not met, the object detection device 1 ends the object detection operation.

[0075] In the object detection operation, the transmission control unit 51 determines the arrival of the transmission processing start timing at a predetermined period. The predetermined period is, for example, a period of several hundred milliseconds. The arrival of the transmission processing start timing is determined using a timing unit such as a timer provided in the control unit 5. If the transmission processing start timing arrives, the transmission control unit 51 outputs a control signal to the drive signal generating unit 3. Thus, the transmission processing is executed.

[0076] Specifically, when the control signal is input, the drive signal generating unit 3 generates a drive signal and outputs it to the transceiver 2, that is, the transceiver circuit 22. The drive signal is output from the transmission process start timing to the transmission process end timing.

[0077] The transceiver circuit 22 drives the transducer 21 based on the input drive signal. In this way, the transducer 21 transmits ultrasonic waves, i.e., transmission waves, of a frequency corresponding to the frequency of the drive signal toward the outside of the vehicle. In this way, the object detection device 1 repeatedly transmits the transmission waves at a predetermined period during the object detection operation. Therefore, the above-mentioned predetermined period is also referred to as a "transmission period".

[0078] When the transmission processing end timing arrives, the transceiver 2 outputs a reception signal which is an AC voltage signal. Immediately after the transmission processing end timing, reverberation occurs in the transceiver 2. Therefore, the transceiver 2 outputs a reverberation signal.

[0079] During the specified receivable period in the object detection operation, the transceiver 2 performs the receiving operation. In the configuration of the present embodiment of the transceiver-integrated type, the receivable period is the period between the end timing of the transmission process in the current transmission process and the start timing of the transmission process in the next transmission process, excluding the dead zone caused by the influence of reverberation, etc. During the receivable period, the transceiver 2 outputs an AC voltage signal corresponding to the amplitude and frequency of the received wave, that is, a received signal.

[0080] The received signal processing unit 4 generates an amplitude signal and a frequency signal by performing various signal processing on the received signal. Specifically, the filter processing unit 41 removes noise from the received signal by performing filtering processing on the received signal. The amplitude signal generating unit 42 generates an amplitude signal based on the received signal after filtering processing by the filter processing unit 41. The frequency signal generating unit 43 generates a frequency signal based on the received signal after filtering processing by the filter processing unit 41. The received signal processing unit 4 outputs the generated amplitude signal and frequency signal to the control unit 5.

[0081] In the control unit 5, the amplitude signal acquisition unit 54 acquires the amplitude signal from the amplitude signal generation unit 42. The frequency signal acquisition unit 55 acquires the frequency signal from the frequency signal generation unit 43. The reception determination unit 59 performs various operations such as determination, diagnosis, and detection related to the reception signal based on the amplitude signal acquired by the amplitude signal acquisition unit 54 and the frequency signal acquired by the frequency signal acquisition unit 55.

[0082] Specifically, the reverberation measurement unit 591 measures the reverberation frequency. The diagnosis unit 592 determines whether an abnormality has occurred in the transceiver 2 based on the measurement result of the reverberation frequency by the reverberation measurement unit 591. When the diagnosis unit 592 determines that an abnormality has occurred, it performs processing corresponding to the type of abnormality determined. For example, when the diagnosis unit 592 determines that a foreign object is attached to the transceiver surface 23, it sends an attachment determination signal to an external device not shown. As a result, an alarm is issued to the passengers of the vehicle to the effect that a foreign object such as mud or snow is attached to the ultrasonic sensor.

[0083] The code determination unit 593 determines the code corresponding to the frequency modulation method in the received wave when detecting the object B. That is, the code determination unit 593 determines whether the received wave is a regular wave based on the frequency signal acquired by the frequency signal acquisition unit 55 and the predetermined reference signal stored in advance. When the received wave is a regular wave, the object detection unit 594 detects the existence 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 unit 54.

[0084] The transceiver surface 23 in the transducer 21 is exposed to the external space of the vehicle when mounted on the vehicle. Therefore, there is a case where foreign matter such as mud and snow is attached to the transceiver surface 23. If foreign matter is attached to the transceiver surface 23, the resonant frequency in the transceiver 2 changes. If the driving frequency before the foreign matter is attached is still directly applied despite this, the intensity of the transmission wave is inadvertently reduced, and the transmission and reception characteristics are reduced. In addition, when the transmission wave is chirped, the modulation method, that is, the change method of the frequency in the transmission wave deviates from the prescribed method due to the attachment of foreign matter. In this way, the recognition rate of the code is reduced.

[0085] In this regard, as the resonance frequency changes due to the attachment of foreign matter, the reverberation frequency also changes. Therefore, the transmission control unit 51 corrects the driving frequency based on the measurement result of the reverberation frequency of the transceiver 2. Then, the filter characteristic setting unit 53 adjusts the frequency band of the signal passing through the filter processing unit 41 to be suitable for the corrected driving frequency. As a result, even in an environment where foreign matter such as mud and snow is easily attached to the ultrasonic sensor, good transmission and reception characteristics and code recognition rate can be achieved.

[0086] In addition, a predetermined error may occur in the measurement result 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 that inappropriate or excessive corrections may be made in the correction of the driving frequency based on the measurement result of the reverberation frequency. In this regard, the transmission control unit 51 protects, i.e. limits, the correction value of the driving frequency determined based on the measurement result of the reverberation frequency by a protection value. That is, for example, the transmission control unit 51 makes the correction value of the driving frequency or its change amount within a predetermined range. Specifically, for example, the transmission control unit 51 can limit the absolute value of the correction value or its change amount to less than a predetermined value. Thereby, inappropriate or excessive corrections can be well suppressed.

[0087] As is well known, when an object B exists at a close distance, the reception timing of the reflected wave may be caused by the reverberation. Figure 2 As shown, in the transceiver 2, in addition to the series resonant circuit RCs caused by the transducer 21, a parallel resonant circuit RCp caused by the connection between the transducer 21 and the transceiver circuit 22 is formed. Therefore, the reverberation frequency is affected by the parallel resonant frequency based on the parallel resonant circuit RCp in addition to the series resonant frequency based on the series resonant circuit RCs. Due to the adhesion of foreign matter, the circuit constant in the series resonant circuit RCs changes, while the circuit constant in the parallel resonant circuit RCp does not change. Therefore, under the transceiver condition where the influence of the parallel resonant frequency becomes large, there is a concern that the accuracy of abnormality determination based on the measurement result of the reverberation frequency and the drive frequency correction may not necessarily be good.

[0088] Therefore, this embodiment performs pre-driving and pre-measurement for reducing the transmission and reception characteristics before the main driving and main measurement for detecting the object B. Specifically, the transmission control unit 51 and / or the circuit characteristic setting unit 52, which are the characteristic setting units for setting the transmission and reception characteristics in the transceiver 2, reduces the transmission and reception characteristics when measuring the reverberation frequency by the reverberation measurement unit 591 compared to when detecting the object B by the object detection unit 594.

[0089] Figure 3 The schematic diagram shows the pre-driving and pre-measurement performed in the pre-measurement period Tp, and the main driving and main measurement performed in the subsequent main measurement period Tm. Figure 3 In FIG. 1 , the vertical axis S represents the received signal, and the horizontal axis T represents the time. In addition, Dp represents the drive signal in the pre-drive, and Dm represents the drive signal in the main drive. SZp represents the reverberation signal in the pre-measurement, and SRp represents the received signal of the reflected wave in the pre-measurement. SZm represents the reverberation signal in the main measurement, and SRm represents the received signal of the reflected wave in the main measurement. Tz is the measurement interval for the reverberation frequency measurement.

[0090] Pre-driving is the output of a driving signal that is performed for the first time immediately after the object detection condition is satisfied. That is, if the object detection condition is satisfied, the object detection device 1 first performs pre-driving and pre-measurement, and then performs main driving and main measurement using the result of pre-measurement.

[0091] The transmission control unit 51 reduces the sound pressure during the pre-driving for the measurement of the reverberation frequency by the reverberation measurement unit 591, i.e., the pre-measurement, compared with the main driving for the detection of the object B by the object detection unit 594. That is, the transmission control unit 51 performs the pre-driving under the condition that the output is limited compared with the main driving. Specifically, the transmission control unit 51 sets the number of pulses in the pre-driving to be smaller than the number of pulses in the main driving.

[0092] Thus, the influence of the parallel resonant circuit RCp during the measurement of the reverberation frequency can be reduced as much as possible. That is, the generation of the beat can be well suppressed by reducing the number of pulses. In addition, the influence of the pre-drive on the main drive and the main measurement can be suppressed as much as possible. Furthermore, the influence of the reflected wave caused by the object B existing in the close range during the measurement of the reverberation frequency can be reduced as much as possible. Therefore, the reverberation frequency can be measured with high accuracy, the abnormality judgment based on the measured reverberation frequency and the drive frequency correction can be performed. In addition, the pre-measurement period Tp can be shortened as much as possible.

[0093] In this embodiment, the transmission control unit 51 performs frequency modulation of the transmission wave as a chirped wave when the object detection unit 594 detects the object B. This improves the accuracy of distinguishing between regular waves and irregular waves. In particular, by encoding the transmission wave with multiple bits, the recognition accuracy can be further improved.

[0094] On the other hand, if the driving frequency is frequency modulated, it becomes difficult to measure the reverberation frequency stably with good accuracy because the reverberation frequency is affected by the driving frequency. Therefore, the transmission control unit 51 controls the transmission of the transmission wave in the transceiver 2 so as not to frequency modulate the transmission wave when measuring the reverberation frequency based on the reverberation measurement unit 591. That is, the driving signal in the pre-driving is a CW driving signal of a single frequency. As such a single frequency, for example, the design value of the series resonance frequency can be used. As a result, the reverberation frequency can be stably measured with good accuracy.

[0095] The circuit characteristic setting unit 52 sets the transceiver circuit 22 to different circuit characteristics during the measurement of the reverberation frequency by the reverberation measuring unit 591, that is, the pre-measurement, and during the main measurement for detecting the object B by the object detecting unit 594. Specifically, the circuit characteristic setting unit 52 sets the parallel resonant circuit RCp in the transceiver circuit 22 to different parallel connection states of resistances during the pre-measurement and the main measurement. More specifically, the circuit characteristic setting unit 52 sets the parallel resonant circuit RCp in the transceiver circuit 22 to different parallel connection states of resistances during the pre-measurement and the main measurement. Figure 2 The switch SW shown is closed, but is open during the main measurement.

[0096] Figure 4A The frequency characteristics of the transmission and reception sensitivity in the transceiver 2 in the state where the switch SW is turned on are shown. Figure 4B The frequency characteristics of the transmission and reception sensitivity in the transceiver 2 in the state where the switch SW is turned off are shown.

[0097] like Figure 2 As shown in FIG. 1 , the transceiver 2 has a series resonant circuit RCs and a parallel resonant circuit RCp in the equivalent circuit. Therefore, under the premise of a driving frequency substantially equal to the series resonant frequency, the frequency characteristic of the transceiver sensitivity in the state where the switch SW is turned off is as follows: Figure 4B As shown by the solid line in the middle, it becomes a form with two peaks sandwiching such a driving frequency. The frequencies corresponding to these two peaks are generated by the 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. In addition, even if the circuit constants such as the resistance value in the parallel resonance circuit RCp are optimized in the state where the switch SW is turned off, as shown in FIG. Figure 4B As shown by the middle dotted line, the frequency characteristic is limited to two peaks connected approximately horizontally.

[0098] On the other hand, by turning on the switch SW, the resistor R2 and the resistor R3 are connected in parallel. This state is almost equivalent to reducing the resistance value of the resistor R2. In this state, Figure 4A As shown, the frequency difference between the two peaks described above is reduced, and typically can be regarded as a state where the peak is one. In this state, the beats in the reverberation are reduced. In addition, the difference between the resonant frequency and the reverberation frequency in the transceiver 2 is reduced, and the accuracy of establishing the correspondence between the measured reverberation frequency and the resonant frequency is improved. Therefore, the reverberation frequency can be measured with higher accuracy, and abnormality judgment and drive frequency correction based on the measured reverberation frequency can be performed.

[0099] Figure 5A as well as Figure 5B An example of a reverberation signal is shown. Figure 5B is Figure 5A A magnified view of the area enclosed by the dashed quadrilateral in FIG. Figure 5A as well as Figure 5B In the figure, the horizontal axis T represents the time, and S represents the reverberation signal waveform. Figure 5AIn the formula, Tv represents the application interval of the driving signal, i.e., the transmission interval, SA represents the amplitude signal corresponding to the reverberation signal, and f represents the frequency signal. THr represents the reverberation time determination threshold. The time interval in which reverberation occurs, i.e., the starting point of the reverberation time, can be determined as the time point a predetermined time after the reference time Tr at which the amplitude signal decreases to the reverberation time determination threshold THr after the end of the transmission interval Tv.

[0100] As mentioned above, the reverberation frequency is affected by the parallel resonant frequency of the parallel resonant circuit RCp in addition to the series resonant frequency of the series resonant circuit RCs. In this way, due to the generation of multiple reverberation frequency components, the reverberation signal generates beats. Figure 5A as well as Figure 5B As shown in the portion surrounded by the dotted ellipse in FIG. 1 , the beat generated in the reverberation signal appears as a waveform break in the reverberation signal and the amplitude signal corresponding to the amplitude thereof.

[0101] like Figure 5A In a time interval including a beat or a waveform break, such as the time intervals Tg1 and Tg2 in FIG. 1 , a peak-shaped reverberation frequency that greatly deviates from the frequency characteristics of the transceiver 2 is observed. Therefore, if the reverberation frequency is measured in such a time interval, the measurement accuracy is greatly reduced. On the other hand, in a time interval without a waveform break, such as the time intervals Tn1 and Tn2, the variation width of the reverberation frequency is small. In such a time interval, good measurement accuracy of the reverberation frequency can be obtained.

[0102] Therefore, the specific section detection unit 57 detects a specific section that is a generation section in which the generation of beats due to a plurality of reverberation frequency components is confirmed in the reverberation signal, or a non-generation section in which the generation of such beats is hardly confirmed. Then, the measurement section setting unit 58 sets a measurement section for measuring the reverberation frequency by the reverberation measurement unit 591 in the non-generation section based on the detection result of the specific section.

[0103] Specifically, in this embodiment, the specific section detection unit 57 detects, as a generation section, a reverberation break section in which a waveform break occurs in an amplitude signal corresponding to the amplitude of the reverberation signal. Figure 5A In the example of , the specific section detection unit 57 detects the portion where the amplitude signal in the reverberation is less than the reverberation break determination threshold value THd in the time section before the lower end where the amplitude signal in the reverberation decreases in a convergent manner as the generation section. Figure 5A In the example of , the specific intervals detected, that is, the generation intervals are the first generation interval Tg1 and the second generation interval Tg2. The lower end portion is a time interval of a predetermined range near the time Tr.

[0104] The non-generation interval can be determined based on the detected generation interval. That is, the non-generation interval can be determined by removing the generation interval from the reverberation time. Specifically, Figure 5A In the example, by removing the first generation interval Tg1 and the second generation interval Tg2 from the reverberation time determined based on the reference time Tr, the first non-generation interval Tn1 and the second non-generation interval Tn2 are determined. The first non-generation interval Tn1 can also be called a non-generation interval of the time interval before the lower end, that is, an intermediate non-beat interval. The second non-generation interval Tn2 includes the lower end.

[0105] Then, the measurement interval setting unit 58 sets the measurement interval in the time interval after the generation interval is removed, that is, the non-generation interval. Figure 5A In the example of , the measurement interval setting unit 58 sets the measurement intervals in the first non-generation interval Tn1 as the middle non-beat interval and the second non-generation interval Tn2 including the lower end. That is, the measurement interval setting unit 58 sets the first non-generation interval Tn1 and the second non-generation interval Tn2 as the measurement interval Tz.

[0106] This embodiment measures the reverberation frequency in a non-generation interval in which the generation of beats is hardly confirmed. Figure 5A As can be seen from the change in the reverberation frequency in the second non-generation interval Tn2, the reverberation frequency tends to converge to a constant value at the lower end. Therefore, the measurement accuracy of the reverberation frequency is improved. In addition, abnormality determination and drive frequency correction based on the measured reverberation frequency can be performed with high accuracy.

[0107] However, a delay time may occur between the amplitude signal and the frequency signal due to a processing time difference between the amplitude signal generating unit 42 and the frequency signal generating unit 43. Specifically, the amplitude signal generating unit 42 needs to perform filtering processing to generate the amplitude signal. Therefore, when the frequency signal generating unit 43 generates the frequency signal by a zero-crossing method or the like, a relatively large delay time occurs.

[0108] Therefore, the delay correction unit 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. Then, the specific section detection unit 57 detects the specific section based on the correction result of the delay correction unit 56. In this way, the measurement section can be appropriately set.

[0109] In this embodiment, the diagnosis unit 592 determines whether an abnormality has occurred in the transceiver 2 based on the reverberation frequency measured with good accuracy as described above. Figure 5AIn the example, the reverberation frequency in the first non-generation interval Tn1 is caused by both the series resonance and the parallel resonance. The reverberation frequency in the second non-generation interval Tn2 is mainly caused by the series resonance, that is, the mechanical vibration characteristics of the transducer 21. In this way, different information can be included in the reverberation frequencies of the plurality of non-generation intervals.

[0110] Therefore, the measurement interval setting unit 58 sets the measurement interval Tz in each of the plurality of non-generation intervals. Figure 5A In the example, the measurement interval Tz is set in the first non-generation interval Tn1 before the lower end and the second non-generation interval Tn2 including the lower end. Then, the diagnosis unit 592 diagnoses abnormality of the transceiver 2 based on the measurement results of the reverberation frequencies in each of the plurality of measurement intervals Tz.

[0111] That is, for example, the diagnosis unit 592 diagnoses the presence or absence of foreign matter attachment based on the measurement result of the reverberation frequency in the second non-generation interval Tn2, which is the time interval corresponding to the lower end. Thus, it is possible to make a foreign matter attachment determination with high accuracy. In addition, for example, the diagnosis unit 592 determines the presence or absence of abnormality in the transceiver 2 based on the measurement result of the reverberation frequency in the first non-generation interval Tn1, which is the time interval before the lower end, in addition to the second non-generation interval Tn2, which is the time interval corresponding to the lower end. Therefore, according to this embodiment, it is possible to make a highly accurate abnormality determination.

[0112] In this embodiment, the transmission control unit 51 corrects the driving frequency of the transceiver 2 based on the reverberation frequency measured with good accuracy as described above. This can achieve good transmission and reception characteristics. In particular, when chirp encoding is performed on the transmission wave, a good code recognition rate can be achieved.

[0113] As described in detail above, according to the present embodiment, the reverberation signal can be analyzed with as good accuracy as possible. In addition, according to the present embodiment, various operations such as transmission frequency correction and abnormality detection can be appropriately performed based on the analysis results of the reverberation signal with good accuracy. In particular, in the reverberation frequency measurement, when a measurement method such as a zero-crossing method or orthogonal detection using instantaneous values ​​is used in order to reduce the calculation load without using FFT (i.e., fast Fourier transform), there is a concern that the accuracy deterioration caused by the beat becomes significant. In this regard, according to the present embodiment, even if a zero-crossing method is used, the reverberation frequency measurement result can be obtained with good measurement accuracy while reducing the calculation load.

[0114] (Action Example)

[0115] Below, use Figure 6 to Figure 8The flowchart shown is for explaining an example of a specific action or process in the present embodiment. In addition, in the drawings, "step" is simply abbreviated as "S".

[0116] If the object detection condition is met, the CPU in the object detection device 1, i.e., the control unit 5, starts Figure 6 The object detection action is shown in the flowchart of . If the object detection action is started, first in step 601, the object detection device 1 performs a pre-drive. Specifically, the object detection device 1 drives the transducer 21 by using a CW drive signal with a specified smaller number of pulses to transmit a low-output pre-measurement transmission wave. In addition, when the number of pulses is 1 or 2, the drive signal must be a CW drive signal even if the drive frequency mode is not changed. That is, in the pre-drive, even if the drive frequency mode for the main drive, i.e., the chirp wave, is used, it is possible to achieve a CW wave-shaped drive signal and a transmission wave only by reducing the number of pulses.

[0117] Next, in step 602, the object detection device 1 performs pre-measurement. The pre-measurement is started immediately after the pre-drive interval ends, or at a predetermined timing after the pre-drive interval ends. In the pre-measurement, the object detection device 1 measures the reverberation frequency based on the amplitude signal and the frequency signal in the reverberation signal.

[0118] Next, in step 603, the object detection device 1 determines whether an abnormality has occurred in the transceiver 2 based on the measured reverberation frequency. That is, the object detection device 1 determines whether an abnormality has occurred and the type of abnormality based on the measured reverberation frequency and a predetermined reference value. As the reference value of the reverberation frequency, for example, a design value, a value measured when the object detection device 1 is shipped from the factory, etc. can be used.

[0119] If transceiver 2 has some abnormality (ie, step 603 = No), object detection device 1 proceeds to step 604. In step 604, object detection device 1 determines whether the abnormality determined or detected is a type of abnormality that allows object detection to continue, such as foreign matter adhesion, ice, etc.

[0120] If the abnormality disqualifies the object detection operation (ie, step 604 = No), the object detection device 1 executes the process of step 605 and then terminates the object detection operation. The abnormality disqualifies the object detection operation from being continued, for example, a wire breakage.

[0121] In step 605, the object detection device 1 executes various processes when an abnormality occurs that makes it impossible to continue the object detection operation. Specifically, for example, the object detection device 1 executes processes required to report the abnormality of the transceiver 2 to the passengers of the vehicle and / or the service factory.

[0122] If the object detection operation is abnormal and can be continued (i.e., step 604 = Yes), the object detection device 1 performs the processing of step 606 and then proceeds to step 607. In step 606, the object detection device 1 performs the processing required to notify the passengers of the host vehicle that foreign matter is attached or ice is formed on the transceiver 2. If the transceiver 2 is normal (i.e., step 603 = Yes), the object detection device 1 proceeds to step 607.

[0123] In step 607, the object detection device 1 calculates the frequency shift Δf. In this operation example, the frequency shift Δf is the shift amount of the resonance frequency in the transceiver 2. Figure 7 The details of the calculation process of the frequency shift Δf in step 607 will be described later in the flowchart of . Thereafter, the object detection device 1 advances the process to step 608 .

[0124] In step 608, the object detection device 1 determines whether the frequency shift Δf is less than the threshold value Δf_th. When the frequency shift Δf is greater than the threshold value Δf_th (i.e., step 608 = No), the object detection device 1 performs the processing of step 609, and then proceeds to step 610 and beyond. On the other hand, when the frequency shift Δf is less than the threshold value Δf_th (i.e., step 608 = Yes), the object detection device 1 skips the processing of step 609 and proceeds to step 610 and beyond.

[0125] In step 609, the object detection device 1 performs correction processing of the main drive frequency. The main drive frequency is the drive frequency in the main drive. Figure 8 Details of the main drive frequency correction process in step 609 will be described later in the flowchart.

[0126] The object detection device 1 sequentially performs the processing of step 610 to step 614. First, in step 610, the object detection device 1 performs main driving. Specifically, the object detection device 1 drives the transducer 21 using the chirp driving signal to transmit a transmission wave for main measurement to which a code corresponding to the frequency modulation method is assigned.

[0127] Next, in step 611, the object detection device 1 performs the main measurement. Next, in step 612, the object detection device 1 acquires the main measurement result, that is, the amplitude signal and the frequency signal in the main measurement, by the control unit 5. Then, in step 613, the object detection device 1 detects the object B based on the acquired main measurement result.

[0128] In step 614, the object detection device 1 determines whether to terminate the object detection operation. For example, the object detection operation is terminated when the object detection condition changes from being satisfied to being not satisfied. Alternatively, the object detection operation is terminated when a passenger of the vehicle performs a predetermined termination operation.

[0129] If the object detection operation is to be continued (ie, step 614 = No), object detection device 1 returns the process to step 610 and executes the processes of steps 610 to 614 again. On the other hand, if the object detection operation is to be terminated (ie, step 614 = Yes), object detection device 1 terminates the object detection operation.

[0130] Figure 7 Show Figure 6 This is an example of the calculation process of the frequency shift Δf in step 607 in the flowchart shown in FIG. In the calculation process of the frequency shift Δf, the object detection device 1 sequentially executes the processes of steps 701 to 702.

[0131] In step 701 , the object detection device 1 acquires the reference value fr_ref of the reverberation frequency. Specifically, the CPU in the control unit 5 reads the reference value fr_ref of the reverberation frequency from the ROM or the nonvolatile rewritable memory.

[0132] In step 702, the object detection device 1 calculates the frequency shift Δf, which is the shift amount of the resonance frequency in the transceiver 2, based on the measurement result of the reverberation frequency fr. Specifically, the frequency shift Δf is the difference between the measured reverberation frequency fr and the reference value fr_ref.

[0133] In this way, this specific example calculates the frequency shift Δf, which is the shift amount of the resonance frequency in the transceiver 2 , based on the shift amount of the reverberation frequency fr from the reference value fr_ref.

[0134] Figure 8 Show Figure 6 This is an example of the correction process of the main driving frequency in step 609 in the flowchart shown in FIG. In the correction process of the main driving frequency, the object detection device 1 first executes the processes of step 801 to step 804 in sequence.

[0135] In step 801, the object detection device 1 obtains or calculates a provisional correction value Me based on the frequency shift Δf. For example, the provisional correction value Me can be calculated using the frequency shift Δf and a predetermined calculation formula. Specifically, for example, the provisional correction value Me can be calculated based on the sum or product of the frequency shift Δf and a value fc corresponding to the temperature correction, etc. Alternatively, for example, the provisional correction value Me can be obtained using a mapping table or a lookup table that uses at least the frequency shift Δf as a parameter.

[0136] In step 802, the object detection device 1 obtains the last correction value Mp. The last correction value Mp is the value obtained when the object detection device 1 performs the last correction. Figure 6 The correction value M at step 609 in the flowchart shown in FIG. 1 . Specifically, the CPU in the control unit 5 reads the previous correction value Mp from the RAM or the nonvolatile rewritable memory.

[0137] In step 803, the object detection device 1 calculates the correction value difference ΔM. The correction value difference ΔM is the difference between the provisional correction value Me obtained or calculated in step 801 and the previous correction value Mp. In step 804, the object detection device 1 determines whether the absolute value of the correction value difference ΔM is less than a specified value K. The specified value K is a positive number, which is equivalent to the absolute value of the protection value of the correction value M of the driving frequency.

[0138] When the absolute value of the correction value difference ΔM is less than the specified value K (i.e., step 804 = Yes), the object detection device 1 performs 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 current correction value M. The set correction value is stored in RAM or non-volatile rewritable memory in a time series for a specified amount of time.

[0139] When the absolute value of the correction value difference ΔM is greater than the specified value K (i.e., step 804 = No), the object detection device 1 terminates the correction process of the main drive frequency after executing the process of step 806. In step 806, the object detection device 1 sets the value obtained by adding the product of the specified value K and the provisional correction value Me divided by the absolute value of the provisional correction value Me to the previous correction value Mp as the current correction value M. As a result, the current correction value M is protected by K or -K. The set correction value M is stored in a RAM or a non-volatile rewritable memory for a specified amount of time in a time series.

[0140] (Variation Example)

[0141] The present disclosure is not limited to the above-mentioned embodiments. Therefore, the above-mentioned embodiments can be appropriately changed. Representative modified examples are described below. In the following description of the modified examples, the differences from the above-mentioned embodiments are mainly described. In addition, in the above-mentioned embodiments and the modified examples, the same figure marks are attached to the mutually identical or equivalent parts. Therefore, in the description of the following modified examples, for the constituent elements with the same figure marks as the above-mentioned embodiments, as long as there is no technical contradiction or special additional description, the description in the above-mentioned embodiment can be appropriately cited.

[0142] The present disclosure is not limited to the specific device configurations shown in the above embodiments. For example, the object detection device 1 is not limited to a vehicle-mounted configuration, that is, a configuration mounted on a vehicle V. Specifically, for example, the object detection device 1 can also be mounted on a ship or an aircraft.

[0143] The object detection device 1 is not limited to Figure 1As shown in the figure, the object detection device 1 includes one transceiver 2 and one drive signal generator 3. That is, the object detection device 1 may include a plurality of transceivers 2. In this case, the drive signal generator 3 may be provided in the same number as the transceivers 2.

[0144] At least one of the capacitor C3, the resistor R2, and the transformer secondary winding corresponding to the inductance LT in the components of the parallel resonance circuit RCp can be omitted. Specifically, for example, in the case where a parallel resonance can be formed by the capacitor C2 in the transducer 21 and the inductance LT of the transformer secondary winding, the capacitor C3 can also be omitted. In the case of an inverter drive configuration, a transformer is not required. Although there is a case where the resistor R3 is configured not to be used in the main measurement to obtain high sensitivity, the present disclosure is also effective in this case.

[0145] The electro-mechanical energy conversion element included in the transducer 21 is not limited to a piezoelectric element. That is, for example, a capacitive element can be used as such an electro-mechanical energy conversion element.

[0146] There is a case where the two-dimensional position of the object B relative to the vehicle is detected by triangulation using a plurality of transducers 21. In this case, for example, transmission waves having the same frequency characteristics, i.e., codes, can be emitted from the plurality of transducers 21 mounted on the vehicle. In this case, the "regular wave" is a received wave when the vehicle receives a reflected wave of the transmission wave transmitted from the vehicle. In contrast, the "irregular wave" is a received wave when the vehicle receives a reflected wave of the transmission wave transmitted from another vehicle. Thus, the influence of interference between a plurality of vehicles can be well suppressed.

[0147] Alternatively, for example, transmission waves having different frequency characteristics, i.e., code arrays, can be emitted from a plurality of transducers 21 mounted on the vehicle. This makes it easy to strictly distinguish between direct waves that are the same between the transducer 21 on the transmitting side and the transducer 21 on the receiving side, and indirect waves that are different from each other, thereby effectively suppressing erroneous recognition caused by overlapping reflections and the like.

[0148] The object detection device 1 is not limited to a configuration in which the transceiver 2, the drive signal generating unit 3, the received signal processing unit 4, and the control unit 5 are supported by a single sensor housing. For example, all or at least a part of the functional components of the drive signal generating unit 3, the received signal processing unit 4, and the control unit 5 may be provided outside the sensor housing in the ultrasonic sensor.

[0149] The above-mentioned external device may include some of the components of the drive signal generator 3, the reception signal processor 4, and the controller 5. Specifically, for example, some of the transmission controller 51 to the reception determination unit 59 may be provided in the external device.

[0150] The drive signal generator 3 and / or the reception signal processor 4 may be provided in the controller 5. Specifically, for example, the amplitude signal generator 42 and the amplitude signal acquirer 54 may be integrated. Alternatively, the frequency signal generator 43 and the frequency signal acquirer 55 may be integrated.

[0151] In the present embodiment, each of the above-mentioned functional configurations and methods are implemented by a dedicated computer having a CPU, etc. Such a dedicated computer is provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. However, the present disclosure is not limited to such a mode. That is, the control unit 5 is not limited to a well-known microcomputer having a CPU, etc.

[0152] Specifically, for example, the above-mentioned functional configurations and methods can also be implemented by a dedicated computer provided by a processor composed of one or more dedicated hardware logic circuits. Alternatively, the above-mentioned functional configurations and methods can also be implemented by one or more dedicated computers composed of a combination of a processor and a memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. That is, all or part of the control unit 5 can also be a digital circuit configured to implement the above-mentioned functions, such as an ASIC or FPGA such as a gate array. ASIC is the abbreviation of Application Specific Integrated Circuit. FPGA is the abbreviation of Field Programmable Gate Array.

[0153] In addition, the computer program can also be stored in a non-migrating physical storage medium that can be read by the computer as an instruction executed by the computer. That is, the device or method of the present disclosure can also be expressed as a computer program containing a sequence for implementing the above-mentioned functions or methods, or a non-migrating physical storage medium storing the program.

[0154] In the above-mentioned embodiment, the functional components constituting the characteristics of the present disclosure are provided in the control unit 5. Therefore, the device of the present disclosure can be evaluated as the control unit 5 as an object detection control device. However, the present disclosure is not limited to such a method. That is, for example, the device of the present disclosure can also be evaluated as an object detection device 1 including a transceiver 2, etc. Or, for example, in the case where a part of the transmission control unit 51 to the reception determination unit 59 is provided in an external device, the device of the present disclosure can also be evaluated as the object detection device 1 and / or the external device.

[0155] The present disclosure is not limited to the specific operation mode and processing mode shown in the above-mentioned embodiment. For example, in the above-mentioned specific example, in a trip, the prediction measurement is performed each time the object detection condition is satisfied. However, the present disclosure is not limited to such a method. That is, for example, it is sufficient to perform the prediction measurement once in a trip. Specifically, for example, if the prediction measurement is performed at the moment when the object detection condition is satisfied at the beginning of a trip, the prediction measurement is not performed during the period thereafter until the ignition switch is turned off.

[0156] There is no particular limitation on the code or code array in the drive signal. That is, for example, when the up-chirp is set to "1", the CW is set to "0", and the down-chirp is set to "-1", the drive signal can be given a code containing one or more bits of at least one of "1" and "-1". Specifically, for example, code arrays such as "1, 0", "-1, 0", "1, 1, 0", "1, 0, -1", and "1, 1, 0, -1" can be applied. In addition, the so-called V-shaped chirp can also be used as the up-chirp and the down-chirp. Furthermore, the code or code array in the drive signal may be changeable or not.

[0157] As the code or code array becomes more complex in order to improve the recognition accuracy, there is a concern that the recognition accuracy may be reduced due to changes in the transmission frequency caused by the adhesion of foreign matter, etc. In addition, as mentioned above, in the previous reverberation frequency measurement technology, it is difficult to measure the reverberation frequency with good accuracy due to the influence of the parallel resonant circuit RCp. In this regard, according to the present disclosure, the driving frequency, that is, the transmission frequency, can be well corrected based on the results of the reverberation frequency measurement with good accuracy and stability. Therefore, according to the present disclosure, the improvement of the recognition accuracy brought about by making the code or code array complex can be achieved more reliably.

[0158] The switching of the transmission and reception characteristics between the pre-driving and pre-measurement and the main driving and main measurement may be performed only by the transmission characteristics or only by the reception characteristics. Alternatively, such switching may be performed only in one of the transmission control unit 51 and the circuit characteristic setting unit 52. When such switching is performed only in the transmission control unit 51, the circuit characteristic setting unit 52 can be omitted.

[0159] In pre-driving, at least any one of the following can be used instead of or in combination with the low pulse number.

[0160] M1: Shift the driving frequency from the resonance frequency of the transceiver 2 .

[0161] M2: Reduces the drive current compared to the main drive.

[0162] M3: Reduce the driving voltage compared to the main driving.

[0163] M4: Reduce the duty cycle compared to the main drive.

[0164] M5: Turn on switch SW.

[0165] In the case of M1 above, the driving frequency during pre-driving is set to a value deviated from the central value in the prescribed transmission and reception frequency band. Specifically, for example, such a driving frequency can be set to a value near the upper limit or lower limit in the transmission and reception frequency band. In addition, the "prescribed transmission and reception frequency band" is a range of Si=0 to Sib[dB] when the output or sensitivity is set to Si and Si=0[dB] at the resonance frequency f0. Sib is typically -3[dB], for example. The sensitivity is the sensitivity when the transducer 21 is used as a receiver. In addition, such a transmission and reception frequency band can also be called a "resonance band", "-3dB band" or "3dB band".

[0166] As in M5 above, the circuit characteristic setting unit 52 may turn on the switch SW not only in the pre-measurement but also in the pre-drive. Thus, the output of the drive signal in the pre-drive can be suppressed to a level required for suppressing the reception of unnecessary reflected waves and for reverberation signal analysis.

[0167] If the purpose of measuring the reverberation frequency with good accuracy can be achieved, it is not necessary to perform the pre-measurement. That is, in the method of measuring the reverberation frequency during the reverberation generation period immediately after the driving in the main measurement without performing the pre-measurement, the effect of improving the measurement accuracy can also be obtained by the present disclosure. Specifically, for example, by turning on the switch SW in the reverberation frequency measurement area, the reverberation frequency can be measured with good accuracy.

[0168] The circuit characteristics changed by the circuit characteristics setting unit 52 are not limited to the resistance component. That is, for example, the capacitance component and / or the inductance component may be changed instead of the resistance component or together with the resistance component.

[0169] For example, as a method of changing the characteristics of the parallel resonant circuit RCp, there is also a method of disconnecting the secondary winding of the transformer or the capacitor C3 corresponding to the inductance LT by a switch. By disconnecting the secondary winding of the transformer or the capacitor C3 corresponding to the inductance LT, the parallel resonant frequency shifts, so that the effect of reducing the beat can be obtained.

[0170] The method for calculating the offset of the resonant frequency in the transceiver 2 is also not limited to the above-mentioned specific example. That is, for example, the frequency shift Δf can be calculated based on the reverberation frequency shift Δfr. The reverberation frequency shift Δfr is the difference between the measured reverberation frequency fr and the reference value fr_ref. Specifically, for example, the frequency shift Δf can be calculated using the reverberation frequency shift Δfr and a prescribed calculation formula. Or, for example, the frequency shift Δf can be obtained using a mapping table or a lookup table that uses the reverberation frequency shift Δfr as a parameter. Or, for example, the frequency change rate Rf can be used instead of the frequency shift Δf. In this case, if described according to the above-mentioned specific example, the frequency change rate Rf can be calculated by Rf=fr / fr_ref using the measured reverberation frequency fr and the reference value fr_ref.

[0171] The correction value M of the drive signal is not limited to being obtained based on the difference between the provisional correction value Me and the previous correction value Mp. Specifically, for example, when the frequency change rate Rf described above is used, the correction value M may be the ratio of the provisional correction value Me to the previous correction value Mp. In this case, the corrected drive signal is obtained by multiplying or dividing the correction value M. That is, the correction value M is not limited to being obtained based on the difference between the measured value fr of the reverberation frequency and the reference frequency fr_ref. Specifically, the correction value M may be obtained based on the ratio of the measured value fr of the reverberation frequency to the reference frequency fr_ref.

[0172] The correction value M of the drive signal is not limited to being obtained by comparison with the previous correction value Mp. Specifically, the correction value M may be compared with an initial value measured normally.

[0173] The method of limiting or protecting the correction value M is not limited to the above-mentioned specific example. That is, for example, an upper limit and a lower limit may be set for the correction value M. The upper limit and the lower limit of the correction value M may have the same or different absolute values.

[0174] In addition, for example, the correction value M may be limited based on the ratio to the previous correction value Mp. Specifically, for example, the provisional correction value Me is set to be Rf·Rc. Rc is a value corresponding to temperature correction, etc. In addition, the correction value ratio RMe=Me / Mp is set. In this case, if RMe<KL, the correction value M is set to be KL·Mp. On the other hand, if RMe>KH, the correction value M is set to be KH·Mp. In addition, if KL≤RMe≤KH, the correction value M is set to be Me. Alternatively, for example, the correction value M may be calculated based on the result of moving average of the measured value fr of the reverberation frequency based on the past history, thereby obtaining the effect of limiting the correction value M.

[0175] In the above embodiment, the specific interval detection unit 57 detects the generated interval as a specific interval. Thus, the non-generated interval can be determined. Thus, the specific interval detection unit 57 can be evaluated as indirectly detecting the non-generated interval as a second specific interval different from the first by directly detecting the generated interval as a first specific interval. Specifically, Figure 5A In the example of , the specific section detection unit 57 can evaluate that the first non-generation section Tn1 and the second non-generation section Tn2 are also detected by detecting the first generation section Tg1 and the second generation section Tg2.

[0176] However, the present disclosure is not limited to such a method. That is, for example, the specific section detection unit 57 may directly detect the non-generation section as the specific section. Specifically, the specific section detection unit 57 may detect the lower end as the specific section based on the amplitude signal corresponding to the amplitude of the reverberation signal.

[0177] Fig. 9 An example of a method for detecting the lower end section Ts corresponding to the lower end is shown. Fig. 9 1 shows the amplitude signal and frequency signal of the received signal acquired when the switch SW is turned on. Fig. 9 THs represents a lower end determination threshold value for detecting the lower end section Ts. In this example, in order to make the amplitude convergence determination more reliable, the lower end determination threshold value THs is set to a value lower than the reverberation time determination threshold value THr.

[0178] If you refer to Fig. 9 , the specific section detection unit 57 detects a predetermined time section with the lower end reference time Tsr as the end time as the lower end section Ts. The lower end reference time Tsr is the time when the amplitude signal decreases to the lower end determination threshold value THs after the start time of the reverberation time Trev determined by the time section after the predetermined time back from the reference time Tr. In addition, the reverberation time determination threshold value THr and the lower end determination threshold value THs may be set to the same value by setting the reverberation time determination threshold value THr to the lower threshold side. In addition, the reverberation time is used together with the frequency information for abnormality determination.

[0179] Fig.10 Another example of a method for detecting the lower end interval Ts is shown. Fig.10 The amplitude signal and frequency signal of the received signal obtained when the switch SW is turned off are shown. Fig. 9 and Fig.10 By comparing the above, we can see the effect of reducing the beat and improving the reverberation frequency measurement accuracy brought about by turning on the switch SW.

[0180] In addition, Fig.10In , σ represents the mean square error of the reverberation frequency. σth is a threshold for detecting the lower end section Ts. The specific section detection unit 57 detects a section with less disturbance of the frequency waveform in which the mean square error σ of the reverberation frequency is less than the threshold σth within the reverberation time as the lower end section Ts.

[0181] The detection method of the lower end interval Ts is not limited to the above examples. That is, for example, the lower end interval Ts can be detected based on the matching result of the amplitude signal waveform and the reference waveform for lower end detection. The reference waveform can use a waveform measured in normal conditions. Alternatively, the reference waveform can also be a waveform derived by calculation based on the circuit characteristics of the microphone and the circuit.

[0182] The measurement interval setting unit 58 may set the entire non-generation interval as the measurement interval, or may set a part of the non-generation interval as the measurement interval. Figure 5A , the measurement interval setting unit 58 may set only a predetermined portion of the second non-occurrence interval Tn2 which is reliably the lower end portion as the measurement interval Tz.

[0183] The reverberation frequency measurement accuracy can be further improved by performing multiple reverberation frequency measurements and performing statistical processing. For example, average value calculation, weighted average value calculation, median extraction, smoothing processing, etc. can be used as statistical processing. In the statistical processing, it is also possible to apply the exclusion processing of specified abnormal values ​​or "deviant values".

[0184] Conceptually similar expressions such as "acquire", "detect", "calculate", "calculate", and "estimate" can be replaced with each other as long as no technical contradiction occurs. In addition, the inequality sign in each determination process can be accompanied by an equal sign or not. That is, for example, "above the threshold" can be changed to "exceeding the threshold". Similarly, "below the threshold" can be changed to "less than the threshold".

[0185] Except for the cases where it is specifically stated that they are essential elements and the cases where it is clearly considered to be essential elements in principle, the elements constituting the above-mentioned embodiments are of course not necessarily essential elements. In addition, when referring to the number, amount, range and other numerical values ​​of the constituent elements, except for the cases where it is specifically stated that they are essential values ​​and the cases where it is clearly considered to be limited to specific numerical values ​​in principle, the present disclosure is not limited to the specific numerical values. Similarly, when referring to the shapes, directions, positional relationships, etc. of the constituent elements, except for the cases where it is specifically stated that they are essential and the cases where it is limited to specific shapes, directions, positional relationships, etc. in principle, the present disclosure is not limited to the shapes, directions, positional relationships, etc.

[0186] The modification examples are not limited to the above-mentioned examples. In addition, a plurality of modification examples can be combined with each other. Furthermore, all or part of the above-mentioned embodiment can be combined with all or part of the modification examples.

[0187] (Methods and procedures)

[0188] Each sequence or each process constituting the object detection method of the present disclosure is similar to the above-mentioned embodiments, variations, and Figure 6 to Figure 8 Each sequence or each process shown in the flowchart corresponds to Figure 6 to Figure 8 The program corresponding to the flowchart shown is equivalent to the object detection program of this embodiment.

[0189] Therefore, the present disclosure shown by the above-mentioned embodiment and modification example includes the following viewpoints related to the method and the program. In addition, the following viewpoints can be applied in combination with each other as long as there is no technical contradiction.

[0190] According to the first viewpoint, an object detection method for detecting an object (B) around a moving body (V) includes the following processing. In addition, an object detection program includes the following processing executed by an object detection device (1) configured to detect an object (B) around the moving body by being mounted on the moving body (V). In addition, "processing" can also be replaced by "sequence", "process" or "behavior".

[0191] A process of detecting a specific interval, the specific interval being a generation interval in which the generation of beats caused by a plurality of reverberation frequency components is confirmed in a reverberation signal generated by a transceiver (2), the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflected wave of the transmission wave based on an object, or a non-generation interval in which the generation of such beats is hardly confirmed;

[0192] A process of setting a measurement interval for measuring the frequency of the reverberation signal, that is, the reverberation frequency, in a non-generation interval based on the detection result of the specific interval; and

[0193] The reverberation frequency processing is measured in the set measurement interval.

[0194] According to the second view,

[0195] The process of detecting the specific section includes the process of detecting, as a generation section, a reverberation break section in which a waveform break occurs in an amplitude signal corresponding to the amplitude of the reverberation signal.

[0196] The process of setting the measurement interval includes a process of setting the measurement interval in a non-occurrence interval which is a time interval excluding the occurrence interval.

[0197] According to the third aspect, the process of detecting the specific section includes detecting, as the generation section, a portion where the amplitude signal is less than the reverberation break determination threshold value in a time section before the lower end where the amplitude signal decreases in a convergent manner.

[0198] The fourth view also includes:

[0199] Processing for correcting 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,

[0200] The process of detecting the specific section includes detecting the process of detecting the specific section based on the correction result of the process of correcting the delay time.

[0201] According to the fifth aspect, the process of setting the measurement interval includes the process of setting the measurement interval at the lower end portion which is the non-generation interval in which the amplitude signal corresponding to the amplitude of the reverberation signal decreases in a convergent manner.

[0202] According to the sixth aspect, the process of detecting the specific section includes the process of detecting the lower end as the specific section based on the amplitude signal corresponding to the amplitude of the reverberation signal.

[0203] According to the seventh aspect, the process of setting the measurement interval includes the process of setting the measurement interval in the middle non-beat interval and the lower end portion, which are non-generation intervals in the time interval before the lower end portion.

[0204] The eighth viewpoint also includes:

[0205] Processing for detecting an object based on received waves; and

[0206] The process of setting the transmission characteristics and / or reception characteristics in the transceiver,

[0207] The process of setting the transmission characteristic and / or the reception characteristic includes a process of lowering the transmission characteristic and / or the reception characteristic when measuring the reverberation frequency compared to when detecting the object.

[0208] According to the ninth view,

[0209] The process of setting the transmission characteristics and / or reception characteristics includes the process of controlling the transmission characteristics of the transmission wave.

[0210] The process of controlling the transmission characteristics of the transmission wave includes a process of reducing the sound pressure when measuring the reverberation frequency compared to when detecting the object.

[0211] According to the tenth view,

[0212] The process of setting the transmission characteristics and / or reception characteristics includes the process of setting the circuit characteristics in the transceiver.

[0213] The process of setting the circuit characteristics includes a process of setting the transceiver to different circuit characteristics when detecting an object and when measuring the reverberation frequency.

[0214] According to the eleventh viewpoint,

[0215] The transceiver comprises a transducer (21) having an electrical-mechanical conversion function and a transceiver circuit (22) electrically connected to the transducer.

[0216] The transceiver circuit has a capacitor (C3) and resistors (R2, R3) connected in parallel with the transducer to form a parallel resonant circuit (RC2).

[0217] The process of setting the circuit characteristics includes a process of setting the parallel connection state of the resistors to be different when detecting the object and when measuring the reverberation frequency.

[0218] The twelfth view also includes:

[0219] A process for determining a code corresponding to a frequency modulation method in a received wave; and

[0220] Detection of objects based on code determination results,

[0221] The process of controlling the transmission characteristics of the transmission wave includes controlling the transmission of the transmission wave in the transceiver so that the transmission wave is frequency modulated when detecting an object and the transmission wave is not frequency modulated when measuring the reverberation frequency.

[0222] The thirteenth aspect further includes a process of determining whether or not an abnormality has occurred in the transceiver based on the measurement result of the reverberation frequency.

Claims

1. An object detection device is an object detection device configured to detect an object around the moving body by being mounted on the moving body, wherein: have: a reverberation measuring unit for measuring a reverberation frequency, which is a frequency of a reverberation signal generated in a transceiver, wherein the transceiver transmits a transmission wave as an ultrasonic wave toward the outside and receives a reception wave including a reflection wave of the transmission wave reflected by the object; a specific section detecting unit that detects a specific section, the specific section being a generation section in which generation of beats caused by a plurality of reverberation frequency components is confirmed in the reverberation signal, or a non-generation section in which generation of such beats is hardly confirmed; and The measurement section setting unit sets a measurement section for measuring the reverberation frequency by the reverberation measuring unit in the non-generation section based on the detection result of the specific section.

2. The object detection device according to claim 1, wherein: The specific section detecting unit detects, as the generation section, a reverberation break section in which a waveform break occurs in an amplitude signal corresponding to the amplitude of the reverberation signal. The measurement interval setting unit sets the measurement interval in the non-occurrence interval which is a time interval excluding the occurrence interval.

3. The object detection device according to claim 2, wherein: The specific section detection unit detects, as the occurrence section, a portion in a time section before a lower end where an amplitude signal corresponding to the amplitude of the reverberation signal convergently decreases and where the amplitude signal is smaller than a reverberation break determination threshold.

4. The object detection device according to any one of claims 1 to 3, wherein: further comprising a delay correction unit that corrects a delay time generated between an amplitude signal corresponding to the amplitude of the reverberation signal and a frequency signal corresponding to the reverberation frequency, The specific section detecting unit detects the specific section based on the correction result of the delay correcting unit.

5. The object detection device according to any one of claims 1 to 3, wherein: The measurement interval setting unit sets the measurement interval at a lower end portion of the non-generation interval in which an amplitude signal corresponding to the amplitude of the reverberation signal decreases in a convergent manner.

6. The object detection device according to claim 5, wherein: The specific section detection unit detects the lower end portion as the specific section based on an amplitude signal corresponding to the amplitude of the reverberation signal.

7. The object detection device according to claim 5, wherein: The measurement interval setting section sets the measurement interval in the non-generation interval, that is, the intermediate non-beat interval, and the lower end portion, respectively.

8. The object detection device according to any one of claims 1 to 3, wherein: It also includes a characteristic setting unit, which sets the transmission characteristics and / or reception characteristics in the transceiver. The characteristic setting unit may lower the transmission characteristic and / or the reception characteristic when the reverberation measuring unit measures the reverberation frequency compared to when the object is detected.

9. The object detection device according to claim 8, wherein: The characteristic setting unit includes a transmission control unit for controlling the sound pressure of the transmission wave. The transmission control unit reduces the sound pressure when the reverberation measurement unit measures the reverberation frequency compared to when the object is detected.

10. The object detection device according to claim 8, wherein: The characteristic setting unit includes a circuit characteristic setting unit for setting circuit characteristics in the transceiver. The circuit characteristic setting unit sets the transceiver to have different circuit characteristics when detecting the object and when the reverberation measuring unit measures the reverberation frequency.

11. The object detection device according to claim 10, wherein: The transceiver comprises a transducer having an electro-mechanical conversion function and a transceiver circuit electrically connected to the transducer. The transceiver circuit has a capacitor and a resistor connected in parallel with the transducer to form a parallel resonant circuit. The circuit characteristic setting unit sets the parallel connection state of the resistor to be different when the object is detected and when the reverberation measuring unit measures the reverberation frequency.

12. The object detection device according to any one of claims 1 to 3, wherein: Also available: A code determination unit for determining a code corresponding to a frequency modulation method in the received wave; as well as an object detection unit, detecting the object based on the code determination result of the code determination unit, The transmission of the transmission wave in the transceiver is controlled so that the transmission wave is frequency-modulated when the object detector detects the object, and the transmission wave is not frequency-modulated when the reverberation measurement unit measures the reverberation frequency.

13. The object detection device according to any one of claims 1 to 3, wherein: The device further includes a diagnosis unit for determining whether or not an abnormality has occurred in the transceiver based on a measurement result of the reverberation frequency by the reverberation measurement unit.

14. An object detection method is an object detection method for detecting objects around a moving body, wherein: detecting a specific interval, the specific interval being a generation interval in which generation of beats caused by a plurality of reverberation frequency components is confirmed in a reverberation signal generated by a transceiver, or a non-generation interval in which generation of such beats is hardly confirmed, the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflected wave resulting from the transmission wave being reflected by the object, Based on the detection result of the specific interval, a measurement interval for measuring the frequency of the reverberation signal, that is, the reverberation frequency is set in the non-generation interval. In the set measurement interval, the reverberation frequency is measured.

15. An object detection program product executed by an object detection device configured to detect objects around a moving body by being mounted on the moving body, wherein: The processing performed by the object detection device includes: a process of detecting a specific interval, the specific interval being a generation interval in which generation of beats caused by a plurality of reverberation frequency components is confirmed in a reverberation signal generated by a transceiver, or a non-generation interval in which generation of such beats is hardly confirmed, the transceiver transmitting a transmission wave as an ultrasonic wave toward the outside and receiving a reception wave including a reflected wave resulting from the transmission wave being reflected by the object; Based on the detection result of the specific interval, a measurement interval for measuring the frequency of the reverberation signal, that is, the reverberation frequency is set in the non-generation interval; and The reverberation frequency is measured in the set measurement interval.

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