JP7354848B2 - Object detection device and object detection program - Google Patents

Description

The present invention relates to an object detection device and an object detection program that detect objects around a moving body.

The ultrasonic detection device described in Patent Document 1 transmits ultrasonic pulses toward a target object and receives reflected signals from the target object. It is known that this reflected signal contains noise components such as electromagnetic noise, wind noise, raindrop noise, and tire drainage noise. Therefore, the ultrasonic detection device described in Patent Document 1 discriminates the noise mixed into the reflected signal based on the pulse time width.

Patent No. 5634404

However, in the ultrasonic detection device described in Patent Document 1, when ultrasonic waves transmitted from another vehicle are mixed into received waves as noise, it is not possible to determine this as noise. The present invention has been made in view of the circumstances illustrated above. That is, the present invention provides a device configuration and a program that can determine that, for example, when ultrasonic waves transmitted from another vehicle mix into received waves as noise, this is noise.

The object detection device (1) is configured to be mounted on a vehicle (M) to detect objects (B) around the vehicle .
The object detection device according to claim 1 includes:
A receiver (20B) is provided so as to be able to receive a received wave including a reflected wave from the object of the probe wave transmitted from a transmitter (20A) that is disposed so as to be able to transmit a probe wave that is an ultrasonic wave to the outside. ), it is determined whether the received wave is the reflected wave of the exploration wave by the object or noise from another vehicle different from the vehicle. a reception determination unit (53) that performs a certain noise determination;
an object detection unit (54) that detects the object based on the result of the noise determination;
Equipped with
The reception determination unit determines the propagation time of the received wave, the propagation distance, or the relationship between the propagation physical quantity, which is a physical quantity corresponding to a measured distance that is half the propagation distance, and the amplitude of the received signal. Perform noise judgment.
The object detection program is a program executed by an object detection device (1) configured to be mounted on a vehicle (M) to detect objects (B) around the vehicle .
In the object detection program according to claim 12 , the process executed by the object detection device includes:
A receiver (20B) is provided so as to be able to receive a received wave including a reflected wave from the object of the probe wave transmitted from a transmitter (20A) that is disposed so as to be able to transmit a probe wave that is an ultrasonic wave to the outside. ), it is determined whether the received wave is the reflected wave of the exploration wave by the object or noise from another vehicle different from the vehicle. a reception determination process that performs a certain noise determination;
Object detection processing that detects the object based on the result of the noise determination;
including;
The reception determination process includes a process of performing the noise determination based on a relationship between a propagation physical quantity, which is a physical quantity corresponding to the propagation time or propagation distance of the received wave, and the amplitude of the received signal.

Note that in each column of the application documents, each element may be given a reference numeral in parentheses. However, such reference numerals merely indicate one example of the correspondence between the same elements and specific means described in the embodiments described later. Therefore, the present invention is not limited in any way by the description of the above reference numerals.

FIG. 1 is a block diagram showing a schematic configuration of an object detection device according to a first embodiment. 2 is a graph for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a time chart for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a time chart for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a time chart for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a time chart for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a time chart for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a graph for explaining the operating principle of the object detection device shown in FIG. 1. FIG. 2 is a flowchart showing an example of the operation of the object detection device shown in FIG. 1. FIG. FIG. 2 is a block diagram showing a schematic configuration of an object detection device according to a second embodiment. 9 is a flowchart showing an example of the operation of the object detection device shown in FIG. 8; It is a graph for explaining the principle of operation in the object detection device according to the third embodiment. It is a block diagram showing a schematic structure of an object detection device concerning a third embodiment.

(Embodiment)
Embodiments of the present invention will be described below based on the drawings. Note that if various modifications applicable to one embodiment are inserted in the middle of a series of explanations regarding the embodiment, understanding of the embodiment may be hindered. Therefore, the modified examples will be described together after the description of the embodiment.

(First embodiment: configuration)
Referring to FIG. 1, the object detection device 1 is configured to be mounted on a vehicle C as a moving body to detect an object B around the vehicle C, that is, outside the vehicle C. In this embodiment, the vehicle C is a so-called automobile, and includes a box-shaped body formed by an outer panel member C1. The outer panel member C1 is, for example, a bumper or a body panel, and is formed of a synthetic resin or metal plate. The state in which the object detection device 1 is mounted on the vehicle C is hereinafter referred to as the "vehicle mounted state." Further, the vehicle C on which the object detection device 1 according to the present embodiment is mounted is hereinafter referred to as the "own vehicle".

The object detection device 1 includes a transceiver 2, a drive signal generation section 3, a received signal processing section 4, and a control section 5. The transceiver 2, the drive signal generation section 3, and the received signal processing section 4 are housed in an unillustrated casing of the ultrasonic sensor unit 6. That is, the ultrasonic sensor unit 6 has a configuration in which the transceiver 2, the drive signal generation section 3, and the received signal processing section 4 are housed and supported by a housing.

The ultrasonic sensor unit 6 is a so-called sonar sensor unit, and is fixed to the outer panel member C1 while mounted on the vehicle. The vehicle C is equipped with a plurality of ultrasonic sensor units 6. Each of the plurality of ultrasonic sensor units 6 is connected to the control section 5 via an in-vehicle network line so as to be able to communicate information. Note that in FIG. 1, only one of the plurality of ultrasonic sensor units 6 is shown for simplicity of illustration.

The transceiver 2 is configured to transmit an exploration wave, which is an ultrasonic wave, to the outside, and to receive a reflected wave of the exploration wave from the object B. Specifically, the transceiver 2 includes a transmitter 20A and a receiver 20B. The transmitter 20A is provided so as to be able to transmit probe waves to the outside. The receiving section 20B is provided so as to be able to receive a received wave including a reflected wave from the object B of the exploration wave transmitted from the transmitting section 20A.

In this embodiment, the ultrasonic sensor unit 6 has an integrated transmitting and receiving configuration. That is, the ultrasonic sensor unit 6 is configured to include one transmitter/receiver 2 so that the transmitter/receiver 2 performs a transmitting/receiving function.

Specifically, the transceiver 2 has one transducer 21. The transmitting section 20A and the receiving section 20B are configured to implement a transmitting function and a receiving function using a common transducer 21. That is, the transducer 21 transmits a probe wave having a frequency corresponding to the frequency of the drive signal, which is an input electric signal, and also transmits a received signal, which is an electric signal, according to the intensity and frequency of the received wave, which is the received ultrasonic wave. is configured to output. In this embodiment, the transducer 21 has a configuration as a resonant ultrasonic microphone in which an electro-mechanical energy conversion element such as a piezoelectric element is built into a substantially cylindrical microphone housing.

Moreover, in this embodiment, the transceiver 2 is configured to be able to transmit exploration waves having a plurality of frequencies, that is, a first frequency f1 and a second frequency f2 different from this. Specifically, the transceiver 2 has, for example, wideband characteristics. Alternatively, for example, the transceiver 2 has a configuration as a so-called multi-resonance microphone having a plurality of resonance frequencies. That is, the transceiver 2 has a first resonant frequency fr1 corresponding to the first frequency f1 and a second resonant frequency fr2 corresponding to the second frequency f2.

When mounted on the vehicle, the transducer 21 is placed in a position facing the outer surface of the vehicle, so that it can transmit exploration waves to the outside of the vehicle and receive reflected waves from outside the vehicle. There is. Specifically, when mounted on the vehicle, the transducer 21 is mounted on the outer panel of the vehicle so that the transmitting and receiving surface 21a is exposed to the external space of the vehicle through the mounting hole C2, which is a through hole formed in the outer panel member C1 of the vehicle. It is attached to member C1. The transmitting/receiving surface 21a is the outer surface of the microphone housing of the transducer 21, and is provided to function as a transmitting surface for exploration waves and a receiving surface for received waves.

The transceiver 2 includes a transducer 21, a transmitting circuit 22, and a receiving circuit 23. Transducer 21 is electrically connected to transmitting circuit 22 and receiving circuit 23 . The transmitter 20A includes a transducer 21 and a transmitter circuit 22. Further, the receiving section 20B is composed of a transducer 21 and a receiving circuit 23.

The transmitting circuit 22 is configured to drive the transducer 21 based on the input drive signal, thereby causing the transducer 21 to emit a probe wave having a frequency corresponding to the frequency of the drive signal. The frequency of the drive signal is hereinafter referred to as "drive frequency." Further, the frequency of the exploration wave will be referred to as a "transmission frequency" hereinafter. Note that to simplify the explanation, in this embodiment, it is assumed that the driving frequency substantially matches the transmission frequency.

Specifically, the transmitting circuit 22 includes a digital/analog conversion circuit and the like. That is, the transmission circuit 22 is configured to perform signal processing such as digital/analog conversion on the drive signal output from the drive signal generation section 3 to generate the element input signal. The element input signal is an AC voltage signal for driving the transducer 21. Then, the transmitting circuit 22 applies the generated element input signal to the transducer 21 to drive the electro-mechanical energy conversion element in the transducer 21, thereby exciting the transmitting/receiving surface 21a and transmitting the probe wave to the outside. It is configured.

The receiving circuit 23 is configured to generate a received signal corresponding to the reception result of the received wave by the transducer 21 and output it to the received signal processing section 4 . Specifically, the receiving circuit 23 includes an amplifier circuit, an analog/digital conversion circuit, and the like. That is, the receiving circuit 23 is configured to generate a received signal by subjecting the element output signal outputted by the transducer 21 to signal processing such as amplification and analog/digital conversion. The element output signal is an AC voltage signal generated by the electro-mechanical energy conversion element provided in the transducer 21 when the transmitter/receiver surface 21a is excited by reception of the received wave. Further, the receiving circuit 23 is configured to output the generated received signal, which includes information regarding the amplitude and frequency of the received wave, that is, the element output signal, to the received signal processing section 4 . The frequency of the received wave will be referred to as the "reception frequency" hereinafter.

In this way, the transmitter/receiver 2 uses the transducer 21 to transmit the probe wave and receive the reflected wave from the object B as a received wave, thereby generating a received signal according to the distance between the transducer 21 and the object B and the receiving frequency. is configured to generate. The received wave when the transceiver 2 receives a reflected wave of the probe wave transmitted by itself is hereinafter referred to as a "normal wave." On the other hand, received waves resulting from exploration waves from other devices are hereinafter referred to as "irregular waves." "Other devices" also include other transceivers 2 mounted on other vehicles different from the own vehicle.

The drive signal generation unit 3 is provided to generate a drive signal based on the control signal received from the control unit 5 and output it to the transceiver 2 , that is, the transmission circuit 22 . The drive signal is a signal for driving the transceiver 2, that is, the transmitter 20A, to cause the transducer 21 to transmit a probe wave. The control signal is a signal for controlling the output of the drive signal from the drive signal generation section 3 to the transceiver 2.

The received signal processing section 4 is configured to generate information or signals necessary for object detection operations in the control section 5 by performing various signal processing on the received signals, and to output such signals to the control section 5. It is being Specifically, the received signal processing section 4 includes an amplitude generation section 40, a distance calculation section 41, a bandpass filter 42, and an amplitude generation section 43.

The amplitude generating section 40 is provided to obtain the amplitude of the received signal output from the transceiver 2. The distance calculation unit 41 is provided to calculate the measured distance based on the TOF and the amplitude acquired by the amplitude generation unit 40. TOF is an abbreviation for Time of Flight, and is the time required from the transmission of the exploration wave to the reception of the reflected wave. TOF may also be referred to as time of flight. The distance measurement is calculated by multiplying half the propagation time by the speed of sound, assuming that the received wave is a reflected wave of the exploration wave from object B. This is the distance to. The ranging distance is half the propagation distance. The propagation distance is the distance in the ultrasonic propagation path from when the exploration wave reaches the object B from the transducer 21 and is reflected by the object B until the reflected wave from the object B reaches the transducer 21. Specifically, the distance calculation unit 41 calculates the measured distance based on the TOF when the amplitude of the received signal exceeds a predetermined threshold. Further, the distance calculation section 41 is configured to output the calculated distance measurement to the control section 5.

The bandpass filter 42 is provided to selectively pass signals in a specific frequency band. The received signal processing section 4 is provided with a plurality of bandpass filters 42 in response to the fact that the search wave has a plurality of transmission frequencies. Specifically, in this embodiment, the received signal processing unit 4 includes a bandpass filter 42 corresponding to the first frequency f1 and a bandpass filter 42 corresponding to the second frequency f2. The bandpass filter 42 corresponding to the first frequency f1 is configured to pass a signal having a predetermined bandwidth centered on the first frequency f1. Similarly, the bandpass filter 42 corresponding to the second frequency f2 is configured to pass a signal having a predetermined bandwidth centered on the second frequency f2.

The amplitude generation section 43 is provided to generate an amplitude signal by performing various signal processing on the signal that has passed through the bandpass filter 42. The amplitude signal is a signal corresponding to the amplitude of the received signal. The received signal processing section 4 is provided with a plurality of amplitude generating sections 43 corresponding to the plurality of bandpass filters 42 provided therein. Specifically, in the present embodiment, the received signal processing unit 4 includes an amplitude generation unit 43 that generates an amplitude signal based on a signal that has passed through the bandpass filter 42 corresponding to the first frequency f1, and It has an amplitude generation section 43 that generates an amplitude signal based on the signal that has passed through the bandpass filter 42 corresponding to f2. The amplitude generation section 43 is configured to output the generated amplitude signal to the control section 5.

The control unit 5 is a so-called sonar ECU that controls the overall operation of the object detection device 1, and is configured as an in-vehicle microcomputer equipped with a CPU, ROM, nonvolatile rewritable memory, RAM, input/output interface, etc. have. ECU is an abbreviation for Electronic Control Unit. CPU is an abbreviation for Central Processing Unit. ROM is an abbreviation for Read Only Memory. Examples of the nonvolatile rewritable memory include EPROM, EEPROM, flash memory, and magnetic recording media. EPROM is an abbreviation for Erasable Programmable Read Only Memory. EEPROM is an abbreviation for Electrically Erasable Programmable Read Only Memory. RAM is an abbreviation for Random Access Memory. ROM, non-volatile rewritable memory, and RAM are non-transitory tangible storage media. The ROM and/or non-volatile rewritable memory correspond to a non-transient physical storage medium that stores the object detection program according to the present embodiment.

The control unit 5 is configured to be able to execute various operations such as object detection operations in the own vehicle and related notifications by reading and executing programs stored in the ROM or non-volatile rewritable memory. Specifically, the control unit 5 controls the transmission of exploration waves in the transceiver 2 and detects the object B based on the received waves received by the transceiver 2. In this embodiment, the control unit 5 includes a temperature acquisition unit 51, a drive control unit 52, a reception determination unit 53, and an object detection unit 54 as functional configurations implemented on a microcomputer. There is.

The temperature acquisition unit 51 is provided to acquire the environmental temperature. “Environmental temperature” is the temperature around the host vehicle in which the object detection device 1, that is, the transceiver 2 is mounted. Specifically, the temperature acquisition unit 51 is adapted to receive a detected value of the outside temperature by an outside temperature sensor (not shown) mounted on the vehicle C via an in-vehicle network (not shown).

The drive control unit 52 is provided to control the transmission state of the probe wave from the transceiver 2 by outputting a control signal to the drive signal generation unit 3 . Specifically, the drive control unit 52 sets the drive frequency, waveform pattern, output timing, etc. of the drive signal generated and output by the drive signal generation unit 3 using a control signal. That is, the drive control unit 52 controls the transmission timing and transmission waveform of the probe wave.

The reception determination section 53 is provided to perform noise determination based on the reception signal corresponding to the reception result of the reception wave at the reception section 20B. The noise determination is performed by determining whether the received wave received by the receiving section 20B of the transceiver 2 is a reflected wave from the object B of the exploration wave transmitted from the transmitting section 20A of the same transceiver 2, or whether it is a different noise. This is the judgment. “Noise” also includes irregular waves. That is, the noise determination is a determination as to whether or not the received wave is a regular wave. Details of the noise determination and the corresponding functional configuration of the reception determination section 53 will be described later.

The object detection unit 54 is provided to detect the object B based on the information or signal acquired from the reception signal processing unit 4 and the result of noise determination by the reception determination unit 53. Specifically, the object detection unit 54 detects the presence of the object B and the distance between the transducer 21 and the object B based on the measured distance obtained from the distance calculation unit 41 when the received wave is a regular wave. It is supposed to be done.

(Noise judgment)
The principle of noise determination in this embodiment and the corresponding functional configuration of the reception determination section 53 will be explained in detail below.

Here, an example is assumed in which the transducer 21 receives a reflected wave of an exploration wave transmitted from the transducer 21 due to an object B existing at a distance X from the transducer 21. In such a hypothetical example, the received power P _r that is the power of the received wave is expressed by the following equation (1). The received power P _r has a predetermined correspondence with the amplitude of the received signal, and is a value that can be almost equated with the amplitude of the received signal.

In the above equation (1), the first term “P _t G _s /4πX ² ” indicates the diffusion loss when the probe wave is radiated from the transducer 21. The second term "e ^{- mX} " indicates the absorption loss due to the air on the outward path of the exploration wave from the transducer 21 to the object B. The third term "σ" is the reflectance at object B. The fourth term "e ^{- mX} " indicates the absorption loss due to air on the return path of the reflected wave from the object B to the transducer 21. The fifth term “A _s /4πX ² ” indicates the diffusion loss when the reflected wave is reflected at the object B, that is, when it is re-radiated. _Pt is the transmission power of the probe wave, _Gs is the directivity gain during transmission, m is the absorption coefficient indicating absorption loss, and _As is the effective area of the aperture in the transducer 21 and the directivity during reception. This is the receiving sensitivity characteristic determined by the gain.

The absorption coefficient m is expressed by the following formula (2). In the following equation (2), t is temperature, f is frequency, and M is a predetermined constant.

k in the above formula (2) is represented by the following formula (3). In the following formula (3), P0 is saturated vapor pressure, P is atmospheric pressure, and h is relative humidity.

As is clear from the above equation (1), while the probe wave propagates from the transducer 21 to the object B, is reflected by the object B, and propagates from the object B to the transducer 21, the power of the ultrasonic wave is attenuated. Furthermore, as is clear from the above equations (1) to (3), such attenuation has frequency dependence. That is, even if the propagation paths completely match, the degree of attenuation differs between the first frequency f1 and the second frequency f2.

Specifically, if the received power P _r when the transmission frequency is the first frequency f1 is P _r (f1), and the received power P _r when the transmission frequency is the second frequency f2 is P _r (f2), When the first frequency f1<second frequency f2, P _r (f1)>P _r (f2). FIG. 2 shows how the reception amplitude Am decreases as the distance X increases when f1=40kHz and f2=60kHz. In FIG. 2, the reception amplitude Am is the amplitude of the reception signal expressed in decibels. Moreover, the solid line shows the case where f1=40kHz, and the broken line shows the case where f2=60kHz.

For example, assume that a probe wave having the frequency characteristics shown in FIG. 3 is transmitted. In FIG. 3, the horizontal axis T indicates time, and the vertical axis f indicates the transmission frequency. Specifically, in this case, the transmission frequency is set to the first frequency f1 during the period T1 from the search wave transmission start timing TS to the frequency transition timing TT. At the frequency transition timing TT, the transmission frequency changes stepwise to the second frequency f2. During the period T2 from the frequency transition timing TT to the transmission end timing TE, the transmission frequency is maintained at the second frequency f2. Note that, as described later, the present invention is not limited to such frequency characteristics.

FIG. 4 shows how the received amplitude Am changes when a probe wave having the frequency characteristics shown in FIG. 3 is transmitted. In FIG. 4, the vertical axis represents the reception amplitude Am expressed in voltage, and the horizontal axis represents time T. In addition, in FIG. 4, for simplification of illustration and convenience of explanation, the case where the distance X=3 m and the case where the distance X=5 m are shown side by side.

In FIG. 4, the solid line indicates the reception amplitude Am corresponding to the first frequency f1. This corresponds to the amplitude signal generated by the amplitude generation section 43 based on the signal that has passed through the bandpass filter 42 corresponding to the first frequency f1. The dotted line indicates the reception amplitude Am corresponding to the second frequency f2. This corresponds to the amplitude signal generated by the amplitude generation section 43 based on the signal that has passed through the bandpass filter 42 corresponding to the second frequency f2.

As is clear from the results shown in FIG. 4, the attenuation due to the increase in distance X is more pronounced when f2=60 kHz than when f1=40 kHz. Note that time Tu is the point in time when switching from f1=40 kHz to f2=60 kHz is detected in the received signal. The switch from f1=40kHz to f2=60kHz may correspond to a sign in the probe and receive waves. Therefore, time Tu can also be referred to as code detection timing.

5A to 5C schematically show the frequency characteristics of the received voltage V when the received wave is a normal wave and when the received wave is a non-normal wave, that is, noise. In FIGS. 5A to 5C, the horizontal axis T indicates time.

When the received wave is a normal wave, the waveform of the received voltage V includes a transition from the first frequency f1 to the second frequency f2, as shown in FIG. 5A. Further, a predetermined magnitude relationship is established between the received voltage V1 at the first frequency f1 and the received voltage V2 at the second frequency f2, depending on the measured distance. The distance measurement can be calculated, for example, based on the elapsed time from the transmission start timing at the time of detection of switching from the first frequency f1 to the second frequency f2 in the reception voltage V (i.e., time Tu in FIG. 4). .

FIG. 5B shows a case where a transmission wave from another vehicle having a constant transmission frequency f0 is received as noise. In this case, the waveform of the received voltage V does not include a transition from the first frequency f1 to the second frequency f2. Therefore, in this case, it is clear that the received wave is not a reflected wave of the exploration wave having the frequency characteristics shown in FIG.

On the other hand, FIG. 5C shows a case where a transmission wave from another vehicle equipped with an object detection device 1 having the same configuration as that mounted on the host vehicle is received as noise. In this case, the waveform of the received voltage V includes a transition from the first frequency f1 to the second frequency f2, similar to the normal wave shown in FIG. 5A. Therefore, it is difficult to distinguish between noise and a normal wave only based on the waveform characteristics, such as whether or not the waveform includes a transition from the first frequency f1 to the second frequency f2.

However, normally, the transmission time and propagation distance of the probe wave do not match between the normal wave and such noise. That is, such noise is usually transmitted at a different transmission time from that of the regular wave, and has a different propagation distance or propagation time from the regular wave. In many cases, noise has a longer propagation distance than normal waves. Further, for example, interference noise when the own vehicle and another vehicle are running face-to-face usually reaches the transducer 21 of the own vehicle directly without being reflected by an object. Therefore, in the case of interference noise, attenuation is reduced by the reflectance and re-radiation in object reflection. Therefore, interference noise can be detected with a large amplitude even if it comes from a distance.

Therefore, regarding noise, the magnitude relationship between the received voltage V1 at the first frequency f1 and the received voltage V2 at the second frequency f2 deviates significantly from a predetermined magnitude relationship depending on the measured distance. Specifically, for example, in the case of noise, as shown in FIG. 5C, the degree of decrease in the received voltage V2 at the second frequency f2 is greater than in the case of the normal wave shown in FIG. 5A.

Let m1 be the absorption coefficient m when the transmission frequency is the first frequency f1, and let m2 be the absorption coefficient m when the transmission frequency is the second frequency f2. Further, when the transmission frequency is the first frequency f1, the transmission power P _t is P _t1 , the transmission directivity G _s is G _s1 , the reflectance σ is σ1, and the reception sensitivity characteristic A _s is A _s1 . Similarly, when the transmission frequency is the second frequency f2, the transmission power P _t is P _t2 , the reflectance σ is σ2, and the reception sensitivity characteristic A _s is A _S2 . These numbers become constants if the frequency is constant. Therefore, P _t1 /P _t2 , G _s1 /G _s2 , σ1/σ2, and A _S1 /A _S2 are constants.

となる。Ｌは上記のＰ_ｔ１／Ｐ_ｔ２等をまとめた定数である。
この式の両辺をそれぞれデシベル変換すると、

となる。α＝２０・ｌｏｇ_１０ｅ、β＝１０・ｌｏｇ_１０Ｌである。このように、送信周波数が第一周波数ｆ１の場合と第二周波数ｆ２の場合との受信信号の振幅の比をデシベル変換した値と、距離Ｘとの間には、線形関係が成立する。 Therefore, from the above formula (1),

becomes. L is a constant that summarizes the above P _t1 /P _t2 , etc.
If we convert both sides of this equation into decibels, we get

becomes. α=20·log ₁₀ e, β=10·log ₁₀ L. In this way, a linear relationship is established between the distance X and the decibel-converted value of the amplitude ratio of the received signal when the transmission frequency is the first frequency f1 and the second frequency f2.

FIG. 6 schematically shows a map for distinguishing between normal waves and noise. In FIG. 6, the reception amplitude ratio RA on the vertical axis is the ratio of the reception voltage V1 to the reception voltage V2, that is, P _r (f1)/P _r (f2), expressed in logarithm, that is, in decibels.

As shown in FIG. 6, in the case of a normal wave, the reception amplitude ratio RA falls within a predetermined range centered on the solid linear plot corresponding to equation (5) above. The lower threshold RAth1 indicates the lower limit in this predetermined range, and the upper threshold RAth2 indicates the upper limit in this predetermined range.

That is, when the measured distance X is acquired, if the reception amplitude ratio RA falls between the lower threshold RAth1 and the upper threshold RAth2 corresponding to the measured distance X, the received wave is a normal wave. That will happen. On the other hand, if the reception amplitude ratio RA does not fall between the lower threshold RAth1 and the upper threshold RAth2 corresponding to the measured distance X, the received wave is noise.

Based on the above study results, the reception determining unit 53 is configured to perform noise determination based on the waveform characteristics of whether or not a transition from the first frequency f1 to the second frequency f2 is included. Further, the reception determining unit 53 is configured to perform noise determination based on the relationship between a propagation physical quantity, which is a physical quantity corresponding to the propagation time or propagation distance of the received wave, and the amplitude of the received signal. Specifically, the reception determination section 53 includes a distance acquisition section 531, an amplitude relationship acquisition section 532, and a noise determination section 533.

A distance acquisition unit 531 serving as a propagation physical quantity acquisition unit is provided to acquire the measured distance X. Specifically, the distance acquisition unit 531 acquires the measured distance X calculated by the distance calculation unit 41 from the distance calculation unit 41. The measured distance X as a propagation physical quantity is half the propagation distance, and is the distance from the transmitter 20A and the receiver 20B to the object B.

The amplitude relationship acquisition unit 532 is provided to acquire the amplitude relationship. The amplitude relationship is the relationship between the measured distance X acquired by the distance acquisition unit 531 and the amplitude signal. Specifically, in this embodiment, the amplitude relationship is the above-mentioned reception amplitude ratio RA that is acquired or calculated based on the ratio of the first amplitude V1 and the second amplitude V2. That is, the reception amplitude ratio RA is the first amplitude V1, which is the amplitude of the first part corresponding to the first frequency f1, and the second amplitude V2, which is the amplitude of the second part corresponding to the second frequency f2, in the received signal. This is the relationship. Further, the amplitude relationship acquisition unit 532 uses the amplitude of the received signal corrected based on the environmental temperature acquired by the temperature acquisition unit 51 when acquiring the amplitude relationship.

The noise determination unit 533 is provided to determine whether the received wave is noise or a normal wave as a wave reflected by the object B of the exploration wave. In this embodiment, the noise determination unit 533 performs noise determination based on the detection result of a code corresponding to a predetermined frequency transition in the received wave. Specifically, the noise determining unit 533 determines that the received wave is noise when the received wave does not include a waveform characteristic of transition from the first frequency f1 to the second frequency f2. . Further, the noise determination unit 533 determines whether the received wave is a normal wave or noise based on the propagation physical quantity and the amplitude relationship. Specifically, the noise determination unit 533 acquires the lower threshold RAth1 and the upper threshold RAth2 based on the measured distance X acquired by the distance acquisition unit 531. Further, the noise determination unit 533 determines whether the received wave is a normal wave or not, depending on whether the reception amplitude ratio RA acquired by the amplitude relationship acquisition unit 532 falls between the lower threshold RAth1 and the upper threshold RAth2. It is designed to determine whether there is noise or not.

Here, as described above, the amplitude relationship, that is, the reception amplitude ratio RA acquired by the amplitude relationship acquisition section 532 is acquired based on the amplitude corrected by the environmental temperature acquired by the temperature acquisition section 51. Therefore, the reception determination unit 53, that is, the noise determination unit 533, performs noise determination based on the amplitude corrected by the environmental temperature acquired by the temperature acquisition unit 51.

(Operation overview)
The object detection device 1 according to this embodiment, the processing executed thereby, and the object detection program including computer instructions for realizing the processing will be simply referred to as "this embodiment" hereinafter. Hereinafter, an overview of the operation according to this embodiment will be explained together with the effects achieved by this embodiment, with reference to each drawing.

When a predetermined object detection condition is satisfied, the object detection device 1 starts an object detection operation. The object detection conditions include, for example, that the traveling speed of the own vehicle is within a predetermined range, that the shift position of the own vehicle is a traveling position that includes reverse, and so on. When the object detection condition is not satisfied, the object detection device 1 ends the object detection operation.

During the object detection operation, the drive control unit 52 determines the arrival of the transmission start timing TS at predetermined intervals. The predetermined period is, for example, a period of several hundred milliseconds. The arrival of the transmission start timing TS is determined using a timer such as a timer provided in the control unit 5.

When the transmission start timing TS arrives, the drive control section 52 outputs a control signal to the drive signal generation section 3. As a result, the transmission process is executed. When the drive signal generator 3 receives the control signal, it generates a drive signal and outputs it to the transceiver 2, that is, the transmitter 20A. Then, the transmitter 20A transmits a probe wave, which is an ultrasonic wave, toward the space outside the own vehicle.

Specifically, the transmission circuit 22 drives the transducer 21 based on the input drive signal. Then, the transducer 21 transmits an exploration wave which is an ultrasonic wave having a frequency corresponding to the drive frequency. In this way, the object detection device 1 repeatedly transmits exploration waves at a predetermined period during the object detection operation. For this reason, the above-mentioned predetermined period is also referred to as a "transmission period."

The drive frequency, which is the frequency of the drive signal, is the first frequency f1 during the period T1 from the transmission start timing TS to the frequency transition timing TT, and changes stepwise to the second frequency f2 at the frequency transition timing TT. The second frequency is f2 during the period T2 from the transition timing TT to the transmission end timing TE. In the present embodiment, in the transmission process, the object detection device 1, that is, the control unit 5 is a transmitter having a first resonant frequency fr1 corresponding to the first frequency f1 and a second resonant frequency fr2 corresponding to the second frequency f2. A probe wave is transmitted using 20A.

When a predetermined reverberation generation period has elapsed after the transmission end timing TE arrives, the transceiver 2 becomes capable of outputting a reception signal that is an AC voltage signal. The transceiver 2 performs a receiving operation during a predetermined receivable period during the object detection operation. In the configuration of this embodiment, which is an integrated transmission and reception type, the receivable period is the period between the transmission end timing TE in the current transmission process and the transmission start timing TS in the next transmission process, including reverberation, etc. This period excludes the dead zone due to the effects of

The receiving section 20B in the transceiver 2, that is, the transducer 21 receives the received wave. When the received wave is a regular wave, the received wave includes a reflected wave from the object B of the exploration wave transmitted from the transmitter 20A of the transceiver 2. The receiving circuit 23 outputs a receiving signal which is an AC voltage signal according to the amplitude and frequency of the received wave during the receivable period. The received signal processing section 4 performs various signal processing on the received signal to generate information or signals necessary for the object detection operation in the control section 5, and outputs the signals to the control section 5.

Specifically, the amplitude generation unit 40 obtains the amplitude of the received signal output from the transceiver 2. The distance calculation unit 41 calculates the measured distance X based on the TOF and the amplitude acquired by the amplitude generation unit 40. Specifically, for example, the amplitude generation section 40 generates an amplitude signal from the received signal output from the transceiver 2. The distance acquisition unit 41 acquires the wave height value and TOF by detecting the amplitude peak, and calculates the measured distance X based on the acquired wave height value and TOF. Note that the method for calculating the measured distance X is not limited to the above specific example. The measured distance X calculated by the distance calculation section 41 is transmitted to the control section 5.

Further, the received signal is transmitted to the control section 5 after being processed by the bandpass filter 42 and the amplitude generation section 43. Specifically, the bandpass filter 42 corresponding to the first frequency f1 selectively passes signals in a frequency band around the first frequency f1 in the received signal. The amplitude generating section 43 corresponding to the first frequency f1 generates an amplitude signal based on the signal passed through the band pass filter 42 corresponding to the first frequency f1. The bandpass filter 42 corresponding to the second frequency f2 selectively passes signals in a frequency band around the second frequency f2 in the received signal. The amplitude generating section 43 corresponding to the second frequency f2 generates an amplitude signal based on the signal passed through the band pass filter 42 corresponding to the second frequency f2. The amplitude signal generated by the amplitude generation section 43 is transmitted to the control section 5.

In the control unit 5, a reception determination unit 53 executes reception determination processing. The reception determination process includes a noise determination process. Noise determination is a process of determining whether the received wave is a normal wave or noise based on a received signal corresponding to the reception result of the received wave at the receiving unit 20B. In addition to the noise determination process, the reception determination process includes a temperature acquisition process, a propagation physical quantity acquisition process, a temperature correction process, and an amplitude relationship acquisition process.

In the temperature acquisition process, the temperature acquisition unit 51 acquires the environmental temperature. In the propagation physical quantity acquisition process, the distance acquisition unit 531 acquires the measured distance X as the propagation physical quantity calculated by the distance calculation unit 41 from the distance calculation unit 41 . The amplitude relationship acquisition unit 532 acquires the amplitude signal generated by the amplitude generation unit 43 from the amplitude generation unit 43.

In the temperature correction process, the amplitude relationship acquisition unit 532 corrects the acquired amplitude signal using the environmental temperature acquired by the temperature acquisition unit 51. Specifically, for example, it is possible to correct the amplitude signal using a correction value obtained using a calculation formula, lookup table, or map that uses the obtained environmental temperature as a parameter. These calculation formulas, lookup tables, or maps may be created by calculation or compatibility testing based on the above formulas (1) to (3).

In the amplitude relationship acquisition process, the amplitude relationship acquisition unit 532 acquires an amplitude relationship that is the relationship between the measured distance X acquired by the distance acquisition unit 531 and the amplitude signal. Specifically, the amplitude relationship acquisition unit 532 obtains a first amplitude V1, which is the amplitude of the first part corresponding to the first frequency f1, and a second amplitude, which is the amplitude of the second part corresponding to the second frequency f2, in the received signal. The reception amplitude ratio RA, which is the relationship with the amplitude V2, is obtained.

In the noise determination process, the noise determination unit 533 determines whether there is a code detection timing Tu that is the detection timing of the transition from the first frequency f1 to the second frequency f2, the measured distance X as a propagation physical quantity, and the amplitude relationship. Based on the received amplitude ratio RA, it is determined whether the received wave is a normal wave or noise. Note that, as described above, in the amplitude relationship acquisition process, the amplitude signal is subjected to temperature correction processing. Therefore, the noise determination unit 533 performs the noise determination process based on the amplitude of the received signal corrected by the environmental temperature acquired in the temperature acquisition process.

Specifically, the noise determining unit 533 determines that the received wave is noise when the received wave does not include the waveform characteristic of transition from the first frequency f1 to the second frequency f2, that is, the sign. Furthermore, based on the measured distance X, the noise determination unit 533 obtains a lower threshold RAth1 and an upper threshold RAth2 from a calculation formula, a lookup table, or a map. These can be created by calculation or compliance testing based on the above formulas (1) to (3). FIG. 6 shows the lower threshold RAth1 and the upper threshold RAth2. Further, the noise determining unit 533 determines whether the received wave is a normal wave or noise depending on whether the received amplitude ratio RA is within a range between the lower threshold RAth1 and the upper threshold RAth2.

The object detection unit 54 detects the object B based on the result of the noise determination. That is, when the received wave is a regular wave, the object detection unit 54 stores information regarding the reception result of the received wave (for example, distance measurement distance X, etc.) in a predetermined storage area (for example, RAM) as information corresponding to the object B. are stored in chronological order. On the other hand, when the received wave is noise, the object detection unit 54 executes a predetermined noise processing. Specifically, for example, information regarding the reception results of the received waves is stored in the above-mentioned storage area in chronological order while adding a noise flag. Alternatively, for example, the information regarding the reception result of the received wave is deleted without being stored in the storage area.

In this manner, in the present embodiment, the reception determining unit 53 uses the difference in the degree of amplitude attenuation with respect to the propagation distance at each frequency when a plurality of transmission frequencies are used to distinguish between normal waves and noise. Therefore, according to the present embodiment, when ultrasonic waves transmitted from another vehicle mix into received waves as noise, it is possible to accurately determine this as noise. Furthermore, in noise determination, both the detection result of a code corresponding to a predetermined frequency transition in a received wave and the difference in amplitude attenuation degree with respect to propagation distance at each frequency when a plurality of transmission frequencies are used are taken into consideration. That is, for example, if the received wave does not include the waveform characteristic of transition from the first frequency f1 to the second frequency f2, the noise determination unit 533 can determine that the received wave is noise. Furthermore, when the received wave includes a waveform feature of a predetermined frequency transition, the noise determination unit 533 determines whether the received wave is a normal wave or noise based on the propagation physical quantity and the amplitude relationship. be able to. Therefore, a more reliable determination of a normal wave is possible.

When using a plurality of transmission frequencies as in this embodiment, it is common to use a transducer 21 having wideband characteristics. In this regard, if the transducer 21 is configured as a multi-resonance microphone having multiple resonance frequencies, it is possible to improve the determination performance by making the difference between the first frequency f1 and the second frequency f2 as large as possible. It becomes possible.

As is clear from the above equations (1) to (3), the amplitude of the reflected wave is affected by the temperature t. Therefore, in this embodiment, noise determination is performed based on the amplitude of the received signal corrected based on the environmental temperature. Therefore, according to this embodiment, good noise determination accuracy can be achieved.

(Operation example)
An example of specific operations or processing in this embodiment will be described below using the flowchart shown in FIG. 7. Note that in the drawings, "step" is simply abbreviated as "S".

When the object detection device 1, that is, the CPU in the control unit 5 detects reception of a received wave having an intensity or amplitude of a predetermined level or more, it starts a series of processes shown in FIG. In step 701, the CPU obtains the measured distance X from the distance calculation unit 41. In step 702, the CPU obtains an amplitude signal from the amplitude generator 43. In step 703, the CPU performs temperature correction on the obtained amplitude signal, and uses the correction result to obtain the amplitude relationship, that is, the reception amplitude ratio RA.

At step 704, the CPU executes noise determination processing. That is, the CPU determines that the received wave is a normal wave when the reception amplitude ratio RA is within the lower threshold RAth1 and the upper threshold RAth2. On the other hand, if the reception amplitude ratio RA does not fall between the lower threshold RAth1 and the upper threshold RAth2, the CPU determines that the received wave is noise.

If the received wave is a regular wave (that is, step 704 = NO), the CPU executes object detection processing in step 705. On the other hand, if the received wave is noise (that is, step 704=YES), the CPU executes noise processing in step 706.

(Second embodiment)
The second embodiment will be described below with reference to FIG. 8. Note that in the following description of the second embodiment, parts that are different from the first embodiment will be mainly described. Further, in the first embodiment and the second embodiment, parts that are the same or equivalent to each other are given the same reference numerals. Therefore, in the following description of the second embodiment, for components having the same reference numerals as those in the first embodiment, the description in the first embodiment may be used as appropriate unless there is a technical contradiction or special additional explanation. . The same applies to the third embodiment described below.

In this embodiment, the reception determination unit 53 further includes an orientation acquisition unit 534. The azimuth acquisition section 534 is provided to acquire the reception azimuth of the received waves based on the reception results of the plurality of reception sections 20B that are mounted at different positions in the own vehicle. Then, the reception determination section 53 performs noise determination processing based on the amplitude of the received signal corrected by the reception direction acquired by the direction acquisition section 534.

As is clear from the above equations (1) to (3), the amplitude of the reflected wave is affected by the directivity. Specifically, since the directivity differs depending on the frequency, the directivity gain when the transmission frequency is the first frequency f1 is _Gs1 , and the directivity gain when the transmission frequency is the second frequency f2 is _Gs2 . do.
Further, the reception sensitivity characteristic when the transmission frequency is the first frequency f1 is assumed to be A _s1 , and the reception sensitivity characteristic when the transmission frequency is the second frequency f2 is assumed to be A _s2 . Further, when the transmission frequency is the first frequency f1, the received power P _t is P _t1 and the reflectance σ is σ ₁ . Similarly, when the transmission frequency is the second frequency f2, the reception power P _t is P _t2 and the reflectance σ is σ ₂ . These numbers become constants if the frequency is constant. Therefore, P _t1 /P _t2 and σ ₁ /σ ₂ are constants.

となる。
上記式（６）において、Ｍは、上記のＰ_ｔ１／Ｐ_ｔ２等をまとめた定数である。 Then, from the above formula (1),

becomes.
In the above formula (6), M is a constant summarizing the above P _t1 /P _t2 , etc.

となる。上記式（７）において、α＝２０・ｌｏｇ_１０ｅ、β＝１０・ｌｏｇ_１０Ｍである。すなわち、図６に示されている、実線のプロット、および、上側閾値ＲＡｔｈ２と上側閾値ＲＡｔｈ２とによって囲まれた判定窓が、方位に因って図中上下にオフセットする。 If we convert both sides of this equation into decibels, we get

becomes. In the above formula (7), α=20·log ₁₀ e and β=10·log ₁₀ M. That is, the solid line plot and the determination window surrounded by the upper threshold RAth2 and the upper threshold RAth2 shown in FIG. 6 are offset vertically in the figure depending on the orientation.

Therefore, in this embodiment, the receiving direction of the received waves is acquired based on the reception results of the plurality of receiving sections 20B that are mounted at different positions in the own vehicle. Specifically, the receiving direction can be obtained or calculated, for example, by triangulation using received waves from a pair of ultrasonic sensor units 6, that is, the transceiver 2, adjacent in the vehicle width direction.

Further, in this embodiment, noise determination is performed based on the amplitude of the received signal corrected based on the transmission and reception directions acquired in the direction acquisition process. Specifically, for example, it is possible to correct the amplitude signal using a correction value obtained using a calculation formula, a lookup table, or a map that uses the obtained reception direction as a parameter. These calculation formulas, lookup tables, or maps may be created by calculation or compatibility testing based on the above formulas (1) to (3). Therefore, according to this embodiment, good noise determination accuracy can be achieved.

(Operation example)
An example of specific operations or processing in this embodiment will be described below using the flowchart shown in FIG. 9. When the object detection device 1, that is, the CPU in the control unit 5 detects reception of a received wave having an intensity or amplitude of a predetermined level or more, it starts a series of processes shown in FIG.

In step 901, the CPU obtains the measured distance X from the distance calculation section 41 in each of the plurality of ultrasonic sensor units 6. In step 902, the CPU acquires the reception direction by triangulation based on the acquired ranging distance X and the positional relationship in each of the plurality of ultrasonic sensor units 6. In step 903, the CPU acquires an amplitude signal from the amplitude generation section 43 in each of the plurality of ultrasonic sensor units 6.

In step 904, the CPU corrects the acquired amplitude signal based on the reception direction. Note that at this time, the CPU also performs temperature correction. In step 905, the CPU uses the results of temperature correction and azimuth correction to obtain the amplitude relationship, that is, the reception amplitude ratio RA.

At step 906, the CPU executes noise determination processing. If the received wave is a normal wave (that is, step 906 = NO), the CPU executes object detection processing in step 907. On the other hand, if the received wave is noise (that is, step 906=YES), the CPU executes noise processing in step 908.

(Third embodiment)
The third embodiment will be described below with reference to FIGS. 10 and 11.

When a transmitted wave from another vehicle is received as noise, the noise is usually a directly propagating wave that is not reflected by the object B. Therefore, for comparison with the above equation (1), if the propagation distance of the directly propagating wave is 2X, the received power P _r that is the power of the directly propagating wave is expressed by the following equation (8).

As is clear from the comparison between Equation (1) and Equation (8) above, the degree of attenuation with respect to distance differs between normal waves and direct propagation wave noise. Specifically, in the case of a normal wave, the received power P _r , that is, the received amplitude is inversely proportional to "the product of the distance X to the fourth power and ^e2mX ." On the other hand, in the case of direct propagation wave noise, the received power _Pr, that is, the received amplitude, is inversely proportional to "the product of the square of the distance X and ^e2mX ." FIG. 10 shows how the reception amplitude Am decreases as the distance X increases in normal wave and direct propagation wave noise. In FIG. 10, the broken line shows the case of direct propagation wave noise, and the solid line shows the case of normal wave.

FIG. 11 shows a schematic configuration of an object detection device 1 according to this embodiment. In this embodiment, the search wave may have a single frequency. In this case, as shown in FIG. 11, the bandpass filter 42 shown in FIG. 1 etc. may be omitted in the received signal processing section 4. Further, the received signal processing section 4 is provided with a distance calculation section 41 and an amplitude generation section 43 that generates an amplitude signal based on the received signal.

In the present embodiment, the reception determination unit 53 performs noise determination based on whether the measured distance X, which is half the propagation distance, and the amplitude of the received signal satisfy a predetermined relationship. It is provided. Specifically, the amplitude relationship acquisition unit 532 determines that the relationship between the measured distance X and the corresponding amplitude signal is the relationship shown by the solid line in FIG. It is tested whether or not the relationship is inversely proportional to the product of the fourth power of X and ^e2mX . The noise determination unit 533 is configured to perform noise determination processing based on the test result.

In this embodiment, when the measured distance X and the amplitude of the received signal satisfy a predetermined relationship, it is determined that the received signal is a normal wave. On the other hand, if the measured distance X and the amplitude of the received signal do not satisfy a predetermined relationship, it is determined that the received signal is noise. Therefore, according to this embodiment, good noise determination accuracy can be achieved.

(Modified example)
The present invention is not limited to the above embodiments. Therefore, the above embodiment can be modified as appropriate. Typical modified examples will be described below. In the following description of the modified example, differences from the above embodiment will be mainly described. Further, in the above embodiment and the modification, parts that are the same or equivalent to each other are given the same reference numerals. Therefore, in the following description of the modification, the description in the above embodiment may be used as appropriate for components having the same reference numerals as those in the above embodiment, unless there is a technical contradiction or special additional explanation.

The present invention is not limited to the specific device configuration 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 the vehicle C. Therefore, specifically, for example, the object detection device 1 may be mounted on a ship or an aircraft.

The transmitter/receiver 2 is not limited to a so-called integrated transmitter/receiver type. That is, the transceiver 2 may have a configuration in which a transmitter including the transmitting section 20A and a receiver including the receiving section 20B are provided separately from each other. In this case, the measured distance X is the distance from the transmitter 20A or the receiver 20B to the object B.

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.

The received signal processing unit 4 may obtain the amplitudes corresponding to the first frequency f1 and the second frequency f2 from the frequency spectrum obtained by fast Fourier transform of the received signal. In this case, the bandpass filter 42 is omitted. That is, the generation of amplitudes corresponding to each of the plurality of frequencies in the received signal is not limited to the combination of the bandpass filter 42 and the corresponding amplitude generation section 43.

All or part of the drive signal generation section 3 and the received signal processing section 4 may be provided in the control section 5. That is, for example, the ultrasonic sensor unit 6 may include only the transceiver 2. Alternatively, all or part of the control section 5 may be provided in the ultrasonic sensor unit 6.

In this embodiment, each of the above functional configurations and methods are realized by a dedicated computer. Such special purpose computers are provided by configuring a processor and memory that are programmed to perform one or more functions specified by the computer program. However, the present invention is not limited to such embodiments. That is, the control unit 5 is not limited to a well-known microcomputer equipped with a CPU or the like.
Specifically, for example, each of the functional configurations and methods described above may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, each of the functional configurations and methods described above may be implemented in a single unit configured by a combination of a processor and memory configured to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by more than one dedicated computer. That is, all or part of the control unit 5 may be a digital circuit configured to realize the above functions, for example, an ASIC such as a gate array or an FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

Further, the computer program may be stored in a computer-readable non-transitory tangible storage medium as instructions executed by a computer. That is, the apparatus or method according to the present invention can be expressed as a computer program including procedures for realizing each of the above-mentioned functions or methods, or as a non-transitional physical storage medium storing the program.

In the embodiment described above, the control unit 5 is provided with functional components that constitute the features of the present invention. Therefore, the device according to the present invention can be evaluated as the control unit 5 as an object detection control device. However, the present invention is not limited to such embodiments. That is, for example, the device according to the present invention can be evaluated as the object detection device 1 including the transceiver 2 and the like.

The first embodiment and/or the second embodiment and the third embodiment may be used together. That is, for example, the amplitude relationship acquisition unit 532 in the first embodiment and/or the second embodiment determines that the amplitude of the received signal is based on the output of at least one of the plurality of amplitude generation units 43. You may also perform a test to see whether it is inversely proportional to the fourth power of .

In this case, the noise determination unit 533 determines whether the reception amplitude ratio RA is between the lower threshold RAth1 and the upper threshold RAth2, the first determination result, and the range measurement distance X and the amplitude of the received signal. The noise determination process is performed using the second determination result of whether or not the relationship is satisfied.

Specifically, for example, if the first determination result is a "normal wave" and the second determination result is a "normal wave," the noise determination unit 533 determines that the received wave is a regular wave. Similarly, when the first determination result is "noise" and the second determination result is "noise", the noise determination unit 533 determines that the received wave is a regular wave.

On the other hand, if the first determination result and the second determination result do not match, the noise determination unit 533 determines whether the received Determine whether the wave is a normal wave or noise. That is, the noise determination unit 533 calculates or determines the reliability P1 of the first determination result and the reliability P2 of the second determination result. Then, the noise determination unit 533 determines that the received wave is a normal wave based on the first determination result, the reliability P1 of the first determination result, the second determination result, and the reliability P2 of the second determination result. or noise.

Specifically, for example, the noise determination unit 533 calculates or determines the reliability P1 of the first determination result and the reliability P2 of the second determination result, both of which range from a minimum value of 0% to a maximum value of 100%. Then, the noise determination unit 533 adopts the determination result with higher reliability between the reliability P1 of the first determination result and the reliability P2 of the second determination result. Note that the noise determination based on the reliability P1 of the first determination result and the reliability P2 of the second determination result is not limited to the above specific example.

The reliability P1 of the first determination result can be calculated based on reception characteristics such as the intensity and/or SN ratio of the received wave, for example. The reliability P2 of the second determination result can be calculated, for example, based on the magnitude of the error from the relationship shown in equation (1) above. Alternatively, the reliability P2 of the second determination result is such that, for example, the amplitude of the received signal is inversely proportional to the fourth power of the measured distance X at at least one of the first frequency f1 and the second frequency f2. The decision can be made based on whether or not the relationship holds true. Note that the method for calculating or determining the reliability P1 of the first determination result and the reliability P2 of the second determination result is not limited to the above specific example. Specifically, for example, the reliability P1 of the first determination result can be calculated based on the magnitude of the error from the relationship in equation (5) above.

The present invention is not limited to the specific operational aspects and processing aspects shown in the above embodiments. Specifically, for example, the frequency characteristics of the exploration wave are not limited to the specific example shown in FIG. 3 . That is, for example, the first frequency f1 may be greater than the second frequency f2, or the first frequency f1 may be less than the second frequency f2. Further, the exploration wave may have a first frequency f1 to an Nth frequency fN. N is an integer of 3 or more. Furthermore, the switching portion between the Kth frequency fK and the (K+1)th frequency fK+1 is not limited to the step shape shown in FIG. 3. K is an integer of 1 or more.

As is well known, a "ratio" is mathematically equivalent to a logarithmic difference. Furthermore, depending on the conditions, there may be no significant difference in the results between the "ratio" and the "deviation". Therefore, the "amplitude relationship" in the present invention is not limited to amplitude ratio.

The horizontal axis in FIG. 6 may be TOF/2 or TOF instead of the measured distance X. That is, the "propagation physical quantity" in the present invention may be distance or time. Further, by correcting the TOF based on the change in sound speed calculated based on the acquired temperature, the accuracy of noise determination is further improved.

The reception determination unit 53, that is, the noise determination unit 533, determines any one of the time when the amplitude of the received wave exceeds a threshold, the peak time of the amplitude of the received wave, and the detection time of the code corresponding to the frequency transition in the received wave. Noise determination may be performed based on the propagation physical quantity and the amplitude of the received signal within a prescribed time range based on the propagation time. That is, for example, the noise determination unit 533 may perform the noise determination within a predetermined time range based on the amplitude peak detection time. Alternatively, for example, the noise determination unit 533 may detect a code detection timing Tu, which is a frequency transition part in the received signal, and perform noise determination within a predetermined time range based on the detected code detection timing Tu. good. This improves the accuracy of noise determination.

Regarding the third embodiment, the absorption loss e ^-2mX due to the propagation distance "2X" is common to Equation (1) corresponding to normal waves and Equation (8) corresponding to directly propagating wave noise. Therefore, if the influence of such absorption loss e ^-2mX can be excluded, the difference between normal waves and direct propagation wave noise is that the intensity or amplitude is inversely proportional to the fourth power of the measuring distance X or inversely proportional to the square of the measuring distance X. The difference is whether you do it or not. In other words, the "predetermined relationship" in noise determination based on whether or not the measured distance X and the amplitude of the received signal satisfy a predetermined relationship is defined as "If the measured distance is Instead of "the relationship inversely proportional to the product of ^e2mX and e2mX," a relationship in which the value obtained by correcting the amplitude by the absorption loss ^e2mX is inversely proportional to the fourth power of the measured distance X may be used.

From this point of view, the third embodiment may be modified as follows. That is, the amplitude generation unit 43 or the amplitude relationship acquisition unit 532 generates a corrected amplitude signal by correcting the amplitude signal with a correction value that compensates for absorption loss corresponding to the propagation distance. Further, the amplitude relationship acquisition unit 532 tests whether the relationship between the corrected amplitude signal and the measured distance X is inversely proportional to the fourth power of the measured distance X. Then, the noise determination unit 533 executes noise determination processing based on the test result. This aspect can also provide the same effects as the third embodiment.

Expressions that are similar in concept to each other, such as "acquisition," "detection," "calculation," "computation," and "estimation" can be interchanged with each other as long as there is no technical contradiction. Further, the inequality sign in each determination process may be with an equal sign or without an equal sign. That is, for example, "above a threshold" may be changed to "above a threshold". Similarly, "below a threshold" can be changed to "below a threshold".

It goes without saying that the elements constituting the above-described embodiments are not necessarily essential, except in cases where they are specifically specified as essential or where they are clearly considered essential in principle. In addition, if numerical values such as the number, numerical value, amount, range, etc. of a component are mentioned, the specification of the number, unless it is clearly stated that it is essential or if it is clearly limited to a specific number in principle, etc. The present invention is not limited to the number of . Similarly, when the shape, direction, positional relationship, etc. of components, etc. is mentioned, unless it is clearly stated that it is essential, or when it is limited in principle to a specific shape, direction, positional relationship, etc. , the present invention is not limited to its shape, direction, positional relationship, etc.

Modifications are also not limited to the above examples. Also, multiple variants may be combined with each other. Furthermore, all or part of the above embodiments and all or part of the modifications may be combined with each other.

1 Object detection device 20A Transmitter 20B Receiver 51 Temperature acquisition unit 53 Reception determination unit 531 Distance acquisition unit (propagation physical quantity acquisition unit)
532 Amplitude relationship acquisition unit 533 Noise determination unit 534 Direction acquisition unit 54 Object detection unit

Claims (22)

An object detection device (1) configured to be mounted on a vehicle (M) to detect an object (B) around the vehicle ,
A receiver (20B) is provided so as to be able to receive a received wave including a reflected wave from the object of the probe wave transmitted from a transmitter (20A) that is disposed so as to be able to transmit a probe wave that is an ultrasonic wave to the outside. ), it is determined whether the received wave is the reflected wave of the exploration wave by the object or noise from another vehicle different from the vehicle. a reception determination unit (53) that performs a certain noise determination;
an object detection unit (54) that detects the object based on the result of the noise determination;
Equipped with
The reception determination unit determines the noise based on the relationship between the propagation physical quantity, which is a physical quantity corresponding to the propagation time of the received wave, the propagation distance, or a measured distance that is half the propagation distance, and the amplitude of the received signal. make a judgment,
Object detection device. The exploration wave includes a first frequency and a second frequency different from the first frequency,
The reception determination unit includes:
a propagation physical quantity acquisition unit (531) that acquires the propagation physical quantity;
Obtaining an amplitude relationship that is a relationship between a first amplitude that is an amplitude of a first portion corresponding to the first frequency and a second amplitude that is an amplitude of a second portion that corresponds to the second frequency in the received signal. , an amplitude relationship acquisition unit (532),
a noise determination unit (533) that determines whether the received wave is the reflected wave of the exploration wave by the object or the noise, based on the propagation physical quantity and the amplitude relationship;
Equipped with
The object detection device according to claim 1. The propagation physical quantity is a distance from the transmitter and/or the receiver to the object, which is half the propagation distance.
The object detection device according to claim 2. The amplitude relationship is obtained based on the ratio of the first amplitude and the second amplitude,
The object detection device according to claim 2 or 3. further comprising the transmitter having a first resonant frequency corresponding to the first frequency and a second resonant frequency corresponding to the second frequency,
The object detection device according to any one of claims 2 to 4. The noise determination unit performs the noise determination based on a detection result of a code corresponding to a transition between the first frequency and the second frequency.
The object detection device according to any one of claims 2 to 5. The reception determination unit is configured to determine a time when the amplitude of the received wave exceeds a threshold, a peak time of the amplitude of the received wave, and a code corresponding to a transition between the first frequency and the second frequency in the received wave. The noise determination is performed based on the propagation physical quantity and the amplitude of the received signal within a prescribed time range based on the propagation time, with any one of the detection times being the propagation time.
The object detection device according to any one of claims 2 to 6 . The reception determination section is based on an attenuation characteristic of the amplitude of the received signal according to the physical quantity of propagation from when the exploration wave is reflected by the object until the reflected wave is received at the reception section. performing the noise determination;
The object detection device according to any one of claims 1 to 7. The reception determination unit performs the noise determination based on whether the measured distance and the amplitude of the received signal satisfy a predetermined relationship.
The object detection device according to any one of claims 1 to 8. further comprising an orientation acquisition unit (534) that acquires the reception orientation of the received wave based on the reception results of the plurality of reception units mounted at different mounting positions in the vehicle ;
The reception determination unit performs the noise determination based on the amplitude of the reception signal corrected by the reception orientation acquired by the orientation acquisition unit.
The object detection device according to any one of claims 1 to 9. further comprising a temperature acquisition unit (51) that acquires the environmental temperature;
The reception determination unit performs the noise determination based on the amplitude of the reception signal corrected by the environmental temperature acquired by the temperature acquisition unit.
The object detection device according to any one of claims 1 to 10. An object detection program executed by an object detection device (1) configured to be mounted on a vehicle (M) to detect objects (B) around the vehicle ,
The process executed by the object detection device includes:
A receiver (20B) is provided so as to be able to receive a received wave including a reflected wave from the object of the probe wave transmitted from a transmitter (20A) that is disposed so as to be able to transmit a probe wave that is an ultrasonic wave to the outside. ), it is determined whether the received wave is the reflected wave of the exploration wave by the object or noise from another vehicle different from the vehicle. a reception determination process that performs a certain noise determination;
Object detection processing that detects the object based on the result of the noise determination;
including;
The reception determination process is performed based on the relationship between the propagation physical quantity, which is a physical quantity corresponding to the propagation time of the received wave, the propagation distance, or a measured distance that is half the propagation distance, and the amplitude of the received signal. including the process of making a judgment;
Object detection program. The exploration wave includes a first frequency and a second frequency different from the first frequency,
The reception determination process includes:
a propagation physical quantity acquisition process that acquires the propagation physical quantity;
Obtaining an amplitude relationship that is a relationship between a first amplitude that is an amplitude of a first portion corresponding to the first frequency and a second amplitude that is an amplitude of a second portion that corresponds to the second frequency in the received signal. , amplitude relationship acquisition processing,
a noise determination process of determining whether the received wave is the reflected wave of the exploration wave by the object or the noise, based on the propagation physical quantity and the amplitude relationship;
including,
The object detection program according to claim 12. The propagation physical quantity is a distance from the transmitter and/or the receiver to the object, which is half the propagation distance.
The object detection program according to claim 13. the amplitude relationship is obtained based on a ratio of the first amplitude and the second amplitude;
The object detection program according to claim 13 or 14. The process executed by the object detection device includes transmitting the exploration wave using the transmitter having a first resonant frequency corresponding to the first frequency and a second resonant frequency corresponding to the second frequency. further including transmission processing,
The object detection program according to any one of claims 13 to 15. performing the noise determination process based on a detection result of a code corresponding to a transition between the first frequency and the second frequency;
The object detection program according to any one of claims 13 to 16. Any one of the time when the amplitude of the received wave exceeds a threshold, the peak time of the amplitude of the received wave, and the detection time of a code corresponding to the transition between the first frequency and the second frequency in the received wave. one is the propagation time, and the noise determination process is performed based on the propagation physical quantity and the amplitude of the received signal within a prescribed time range based on the propagation time.
The object detection program according to any one of claims 13 to 17. Performing the noise determination based on the attenuation characteristic of the amplitude of the received signal according to the propagation physical quantity from when the exploration wave is reflected by the object until the reflected wave is received by the receiving unit.
The object detection program according to any one of claims 12 to 18. performing the noise determination based on whether the measured distance and the amplitude of the received signal satisfy a predetermined relationship;
The object detection program according to any one of claims 12 to 19. The process executed by the object detection device further includes a direction acquisition process of obtaining a reception direction of the received wave based on the reception results of the plurality of reception units mounted at different mounting positions in the vehicle ,
The reception determination process includes a process of performing the noise determination based on the amplitude of the received signal corrected by the reception direction acquired in the direction acquisition process.
The object detection program according to any one of claims 12 to 20. The process executed by the object detection device further includes a temperature acquisition process of acquiring an environmental temperature,
The reception determination process includes a process of making the noise determination based on the amplitude of the received signal corrected by the environmental temperature acquired in the temperature acquisition process.
The object detection program according to any one of claims 12 to 21.

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