JPWO2021130818A1 - Detection device, detection method, and detection program - Google Patents

Abstract

The detection device (100) calculates a Doppler shift rate corresponding to a peak candidate detection unit (125) for obtaining a correlation peak position and a correlation peak set consisting of a plurality of correlation peak positions, and calculates the Doppler shift rate and the surroundings of the moving body. Using the velocity of the transmitted signal in, it is assumed that it exists around the moving object, the relative velocity between the object corresponding to the correlation peak set and the moving object is calculated, and the value of the relative velocity is the value in the first interference range. If not, it is provided with an exclusion unit (126) that determines that the correlation peak set corresponds to the object.

Description

The present invention relates to a detection device, a detection method, and a detection program.

An object detection device that detects an object around a vehicle using an ultrasonic sensor is known.
As an object detection device, an ultrasonic signal is transmitted using an ultrasonic transmitter, a reflected wave reflected by a surrounding object is received using an ultrasonic receiver, and the reflected wave exists in the received signal. By confirming whether or not the object is detected, an object around the vehicle is detected, and when the object is detected, the distance to the object, the relative position coordinates, the direction, the relative speed, and the like are calculated.
The information of the object around the vehicle detected by the object detection device is used for notifying or warning the driver, controlling the vehicle so as to avoid a collision with the object, and the like.

Patent Document 1 describes a technique for calculating the distance from a vehicle to an object and the speed of the object by using a pair of an up chirp wave and a down chirp wave as a transmission signal.

Japanese Unexamined Patent Publication No. 2017-215241

When the object detection device receives the interference waves, they may mistakenly recognize them as reflected waves from the object. Interference wave is a general term for transmission signals from ultrasonic sensors installed in other vehicles existing around the vehicle, ultrasonic interference signals from some interference signal source, ultrasonic noise, and the like. Therefore, the object detection device needs to distinguish between the interference wave and the reflected wave.
The technique described in Patent Document 1 makes a mistake in pairing a plurality of objects when there are multiple objects and reflection peaks corresponding to a plurality of up chirp waves and a plurality of down chirp waves appear (mispairing). This is to prevent it. Specifically, this technique determines that mispairing is performed when the time derivative value of the calculated distance and the calculated speed do not match.
However, since the technique described in Patent Document 1 relates to a pairing method for a plurality of reflected waves, there is a problem that an interference wave having characteristics different from those of a transmission signal cannot be identified. In addition, since the time derivative value of the distance is calculated using the time series data in order to determine the pair, there is also a problem that it is necessary to send and receive a plurality of times.

An object of the present invention is to distinguish between an interference wave and a reflected wave based on a set of transmission and reception even when the interference wave and the reflected wave are mixed.

The detection device according to the present invention is
Information corresponding to the time when the transmission signal transmitted from the moving body is transmitted, which corresponds to the reference signal having a plurality of strong signal time zones having a strong signal having a large amplitude and a time zone having a plurality of signals having a small amplitude. A receiver that stores the received signal including
The peak that appears in the cross-correlation function regarding the time lag between each of the strong signals and the received signal is detected, and the peak that does not correspond to the transmitted signal is set as the correlation peak, which is the position on the time axis of the cross-correlation function. A peak candidate detection unit that obtains the relative position of the correlation peak with respect to the position of the peak corresponding to the transmission signal as the correlation peak position.
The Doppler shift rate corresponding to the correlation peak set is calculated using the correlation peak set consisting of the plurality of correlation peak positions and the intervals of the plurality of strong signal time zones corresponding to the plurality of correlation peak positions, respectively, and the Doppler is calculated. Using the shift rate and the velocity of the transmitted signal around the moving object, the relative velocity between the moving object and the object that is assumed to exist around the moving object and corresponds to the correlation peak set is calculated. It is provided with an exclusion unit for determining that the correlation peak set corresponds to the object when the value of the relative velocity is not the value of the first interference range.

According to the present invention, the detection device 100 uses a transmission signal having a strong signal time zone having a strong signal having a large amplitude. Then, the exclusion unit 126 discriminates between the interference wave 7 and the reflected wave 4 based on the threshold value corresponding to the interval of the plurality of strong signal time zones even when a plurality of correlation peaks appear in the cross-correlation function. be able to.
Therefore, according to the present invention, even when the interference wave 7 and the reflected wave 4 are mixed, both can be distinguished based on a set of transmission and reception.

The figure which shows the example of the vehicle 1 provided with the detection device 100 which concerns on Embodiment 1, and the situation around the vehicle 1. The hardware block diagram of the detection apparatus 100 which concerns on Embodiment 1. FIG. The functional block diagram of the detection apparatus 100 which concerns on Embodiment 1. FIG. The functional block diagram of the object detection unit 122 according to the first embodiment. The flowchart which shows the operation of the detection apparatus 100 which concerns on Embodiment 1. The flowchart which shows the operation of the detection process of the object detection part 122 which concerns on Embodiment 1. The flowchart which shows the operation of the detection process of the object detection part 122 which concerns on the modification 1 of Embodiment 1. The flowchart which shows the operation of the detection process of the object detection part 122 which concerns on the modification 2 of Embodiment 1. The functional block diagram of the object detection part 122b which concerns on Embodiment 2. FIG. The flowchart which shows the operation of the detection apparatus 100 which concerns on Embodiment 2. The flowchart which shows the operation of the detection process of the object detection part 122b which concerns on Embodiment 2. The functional block diagram of the object detection part 122c which concerns on Embodiment 3. FIG. The flowchart which shows the operation of the detection apparatus 100 which concerns on Embodiment 3. The flowchart which shows the operation of the detection process of the object detection part 122c which concerns on Embodiment 3. The figure explaining the cross-correlation function about the received signal including the reflected wave 4. The figure explaining the cross-correlation function about the received signal including the interference wave 7. The figure which shows the example of a multi-carrier wave. The figure which shows the example of a pair pulse wave.

Embodiment 1.
Hereinafter, the present embodiment will be described with reference to FIGS. 1 to 8 and FIGS. 15 to 18.

*** Explanation of configuration ***
FIG. 1 shows an application example of the detection device 100 according to the present embodiment.
The vehicle 1 includes a transmitter 106 and a receiver 107, and a detection device 100 having a control device 101 for controlling them. Hereinafter, the vehicle 1 will be a four-wheeled vehicle as a specific example. However, the vehicle 1 is not limited to a four-wheeled vehicle, and may be a two-wheeled vehicle or another moving body such as a ship or a submarine.
The transmitter 106 and the receiver 107 are provided on the outer surface of the vehicle 1. The control device 101 is provided inside the vehicle 1 and is connected to a vehicle speed ECU (Electronic Control Unit) 110 connected so as to be able to communicate with the vehicle speed sensor 109.

The control device 101 causes the transmitter 106 to transmit a reference wave used for detecting an object as a transmission wave 3. The receiver 107 receives the reference wave. The reference wave is an ultrasonic wave as a specific example. A reference wave received by the receiver 107 that directly reaches the receiver 107 without being reflected by the object 2 is called a direct wave 5. A reference wave received by the receiver 107, which is a reference wave reflected by the object 2, and is a reference wave other than the direct wave 5, is called a reflected wave 4.
As shown in FIG. 1, when the object 2 is present around the vehicle 1, the transmitted wave 3 is reflected by the object 2 and returns to the vehicle 1 as the reflected wave 4. The detection device 100 detects the object 2 by using the reflected wave 4 received by the receiver 107.

The interference source 6 transmits an interference wave 7 that interferes with the reflected wave 4. The interference wave 7 is a reference wave from a transmitter 106 installed in another vehicle 1, an ultrasonic interference signal from some interference signal source, ultrasonic noise, or the like. As shown in this figure, when the interference source 6 is present in the vicinity of the vehicle 1, the receiver 107 receives the interference wave 7 generated by the interference source 6. At this time, if the detection device 100 cannot distinguish between the reflected wave 4 and the interference wave 7 included in the received signal, the interference wave 7 is mistaken for the reflected wave 4. When the vehicle 1 receives an erroneous result from the detection device 100, the vehicle 1 may erroneously warn, control, or the like.
The arrangement of the transmitter 106 and the receiver 107 is not limited to the position shown in the figure. The receiver 107 may be arranged in an area where the reflected wave 4 corresponding to the transmitted wave 3 from the transmitter 106 can be received, and the front, rear, side, front side, rear side, and upper surface of the vehicle 1 may be arranged. Alternatively, it may be arranged on the lower surface.

FIG. 2 shows a hardware configuration example of the detection device 100 according to the present embodiment. As shown in this figure, the detection device 100 is a general computer.
The detection device 100 may be mounted as an integrated form or a form that cannot be separated from the vehicle 1, other components shown in this figure, or a form that can be removed or separated. It may be implemented as a form that can be used.

As shown in this figure, the detection device 100 includes a control device 101, a transmission amplifier 105, a transmitter 106, a receiver 107, a reception amplifier 108, a vehicle speed sensor 109, a vehicle speed ECU 110, a bus 111, and a signal line 112.

The control device 101 is connected to the vehicle speed ECU 110 via the bus 111, and is connected to the transmission amplifier 105 and the reception amplifier 108 via the signal line 112.
The transmitter amplifier 105 and the transmitter 106, the receiver amplifier 108 and the receiver 107, and the vehicle speed ECU 110 and the vehicle speed sensor 109 are connected via a signal line 112, respectively.

The control device 101 is an ECU and includes a processor 11, a memory 103, and a communication interface 104.
Hereinafter, it is assumed that the reference wave is an ultrasonic wave.
The control device 101 transmits an acoustic signal for transmitting ultrasonic waves to the transmitter 106, and performs object detection processing using the acoustic signal received by the receiver 107 and the speed information received from the vehicle speed sensor 109. ..
Hereinafter, the acoustic signal transmitted by the transmitter 106 is referred to as a transmission signal, and the acoustic signal received by the receiver 107 is referred to as a reception signal.

The processor 11 is a processing device that reads a program or the like stored in the memory 103 and executes the program. The processing device is sometimes called an IC (Integrated Circuit). As a specific example, the processor 11 is a CPU (Central Processing Unit).

The memory 103 is composed of a main storage device 12 that stores temporary data and the like when the processor 11 executes a program, and an auxiliary storage device 13 that stores various parameters such as a program executed by the processor 11 and a threshold value. There is.
The main storage device 12 temporarily stores the reception signal obtained from the receiver 107 and the reception amplifier 108, and the speed information indicating the speed of the vehicle 1 obtained from the vehicle speed sensor 109 and the vehicle speed ECU. As a specific example, the main storage device 12 is a RAM (Random Access Memory).
The auxiliary storage device 13 stores a detection program, an OS (Operating System) 19, and the like, and as a specific example, an HDD (Hard Disk Drive) and a ROM (Read Only Memory). The auxiliary storage device may be a portable recording medium such as a NAND flash. The detection program may be provided as a program product.

The communication interface 104 transmits the transmission signal generated by the processor 11 to the transmission amplifier 105, and receives the reception signal from the reception amplifier 108 and the speed information from the vehicle speed ECU 110.
The communication interface 104 incorporates an analog-digital converter and a digital-analog converter, converts a transmission signal from digital to analog, and converts a received signal from analog to digital.
The communication interface 104 may be composed of one interface for transmitting and receiving a plurality of types of signals, or may be composed of a plurality of interfaces having necessary individual functions.

Other components of the detection device 100 will be described.

The transmission amplifier 105 is connected to the control device 101 via the signal line 112, and is also connected to the transmitter 106 via the signal line 112. The transmission amplifier 105 amplifies the acoustic signal transmitted from the control device 101 and transmits it to the transmitter 106.

The transmitter 106 transmits an acoustic signal based on the signal received from the transmission amplifier 105 to the outside.

The receiver 107 is connected to the receiving amplifier 108 via the signal line 112, and receives an acoustic signal.

The receiving amplifier 108 is connected to the control device 101 via the signal line 112, receives from the receiver 107, amplifies the acoustic signal, and transmits the amplified signal to the control device 101.

Here, the transmitter 106 and the transmitter amplifier 105 may be mounted as an integrated form or a form that cannot be separated, or may be implemented as a form that can be removed or a form that can be separated. You may be.
Similarly, the receiver 107 and the receiving amplifier 108 may be implemented as an integrated form or an inseparable form, or may be implemented as a removable form or a separable form. You may have.
Although the transmitter amplifier 105 and the transmitter 106 and the receiver 107 and the receiver amplifier 108 are described as different hardware, they may be the same hardware.
That is, the transmitting amplifier 105 and the transmitter 106 may be a transmitting ultrasonic sensor having a built-in amplifier, and the receiver 107 and the receiving amplifier 108 may be a receiving ultrasonic sensor having a built-in amplifier. These ultrasonic sensors may be different ultrasonic sensors from each other, or may be one ultrasonic sensor that is used for both transmission and reception.

The vehicle speed sensor 109 is connected to the vehicle speed ECU 110 via the signal line 112, acquires the current speed of the vehicle 1, and transmits the acquired speed to the vehicle speed ECU 110.

The vehicle speed ECU 110 is connected to the control device 101 via the bus 111, and transmits the speed information received from the vehicle speed sensor 109 to the control device 101 via the bus 111. The transmission of speed information is performed at regular intervals.

The vehicle speed sensor 109 may calculate a speed value and use the calculated value as speed information, or may generate a pulse signal proportional to the driving wheel rotation speed of the vehicle 1 and use the generated pulse signal as speed information.
When the vehicle speed ECU 110 receives a pulse signal as speed information, the vehicle speed ECU 110 may convert the pulse signal into a speed.

The bus 111 is a communication line connecting the control device 101 and the ECU.
The in-vehicle network is configured by using the bus 111. In an in-vehicle network, CAN frames defined by a CAN (Control Area Network) protocol are typically transmitted and received.

The signal line 112 is a communication line that does not belong to the in-vehicle network and connects devices such as ultrasonic sensors. Communication signals between the devices are transmitted and received via the signal line 112.

FIG. 3 is an example of a functional block diagram of the control device 101. The configuration of the control device 101 will be described with reference to this figure.
As shown in this figure, the detection device 100 includes a communication interface 104, a synchronization unit 121, an object detection unit 122, a transmission unit 123, and a reception unit 124, and includes a transmission amplifier 105, a reception amplifier 108, and a vehicle speed. It is connected to the ECU 110.
The functions of the functional components of the synchronization unit 121, the object detection unit 122, the transmission unit 123, and the reception unit 124 are realized by the processor 11 executing a program for exerting the functions of each unit.

The transmission unit 123 transmits the transmission signal to the transmission amplifier 105 via the communication interface 104.

The reception unit 124 receives the reference signal from the transmission unit 123, and transmits the reception signal transmitted from the reception amplifier 108 via the communication interface 104 and the reference signal to the object detection unit 122.
The receiving unit 124 may hold the reference signal in the memory 103 in advance and transmit the reference signal to the object detection unit 122 when the object detection unit 122 performs the correlation processing. The receiving unit 124 may hold the waveform data of the reference signal in the memory 103 instead of the reference signal, or may transmit the waveform data of the reference signal to the object detection unit 122 instead of the reference signal.

The synchronization unit 121 has a function of synchronizing the time axis of the transmission unit 123 and the reception unit 124, and makes the transmission start time and the storage start time the same. The transmission start time is the time when the transmission unit 123 starts transmission of the transmission signal. The storage start time is the time when the receiving unit 124 starts storing the received signal.
The synchronization unit 121 synchronizes the time when the moving body transmits the transmission signal with the time when the reception unit 124 starts storing the reception signal. The time when the mobile body transmits the transmission signal is the time when the transmitter 106 transmits the transmission signal.

The vehicle speed ECU 110 transmits speed information to the object detection unit 122.

The object detection unit 122 detects an object using the transmitted received signal and velocity information.

The receiving unit 124 may store the received signal in the memory 103, store the received signal for a predetermined time, and then transmit the received signal to the object detection unit 122. The receiving unit 124 may sequentially transmit the received signal to the object detection unit 122, and the object detection unit 122 may sequentially perform the correlation processing.
Further, the receiving unit 124 may appropriately process the received signal so that the object detecting unit 122 can easily perform the processing, and transmit the processed received signal to the object detecting unit 122.
The predetermined time is, as a specific example, a cycle time. The cycle time is the time from the time when the transmission of a certain transmission signal is started to the time when the next transmission signal is transmitted. The receiving unit 124 may change a predetermined time as needed.

The receiving unit 124 is the time when the transmitted signal transmitted from the moving body is transmitted, which corresponds to the reference signal having a plurality of strong signal time zones having a large amplitude strong signal and a plurality of time zones having a small amplitude signal. The received signal including the corresponding information is stored. The signal having a small amplitude includes a signal having an amplitude of 0. The information corresponding to the time when the transmission signal transmitted from the mobile body is transmitted is, as a specific example, a signal corresponding to the direct wave 5 included in the reception signal.

FIG. 4 is an example of a functional block diagram of the object detection unit 122. The configuration of the object detection unit 122 will be described with reference to this figure.
As shown in this figure, the object detection unit 122 includes a peak candidate detection unit 125, an exclusion unit 126, a distance calculation unit 127, and a speed calculation unit 128.

The peak candidate detection unit 125 analyzes the correlation between the received signal transmitted from the reception unit 124 and the reference signal, and detects the peak candidate of the correlation waveform. The peak candidate detection unit 125 may analyze the correlation by using a transmission signal instead of the reference signal.
The peak candidate detection unit 125 generates a peak candidate set consisting of the detected peak candidates, and transmits the peak candidate set to the exclusion unit 126.

The peak candidate detection unit 125 detects a peak that appears in the cross-correlation function regarding the time lag between each strong signal and the received signal, and sets the peak that does not correspond to the transmission signal as the correlation peak. The peak candidate detection unit 125 obtains the position of the correlation peak relative to the position of the peak corresponding to the transmission signal, which is the position on the time axis of the cross-correlation function, as the correlation peak position.
The time axis of the cross-correlation function is the axis corresponding to the lag of the cross-correlation function. The relative position of the correlation peak with respect to the position of the peak corresponding to the transmission signal corresponds to the time from the transmission start time of the pair pulse L (R) to the appearance of the correlation peak L (R). The path length L (R) shown in 15.

The exclusion unit 126 is a peak candidate corresponding to the interference wave 7 or the reflected wave 4 by using the peak candidate set transmitted from the peak candidate detection unit 125 and the threshold value stored in the memory 103. To identify. The exclusion unit 126 excludes peak candidates due to the interference wave 7 from the peak candidate set. The exclusion unit 126 selects the maximum peak from the peak candidate set and transmits it to the distance calculation unit 127 and the speed calculation unit 128. The position on the time axis corresponding to the maximum peak is defined as the maximum peak position.
The maximum peak is the peak candidate with the maximum amplitude.

The exclusion unit 126 corresponds to the correlation peak set by using the correlation peak set consisting of the plurality of correlation peak positions and the intervals of the plurality of strong signal time zones corresponding to the plurality of correlation peak positions included in the correlation peak set. Calculate the Doppler shift rate. The exclusion unit 126 is assumed to exist around the moving body by using the Doppler shift rate and the velocity of the transmitted signal around the moving body, and moves with the object corresponding to the correlation peak position included in the correlation peak set. Calculate the relative speed with the body. This object is called an assumed object. The hypothetical object may not actually exist. The exclusion unit 126 determines that the correlation peak set corresponds to the object when the value of the relative velocity is not the value of the first interference range.
As a specific example, the correlation peak set is a set consisting of the correlation peak position L and the correlation peak position R. As a specific example, the interval between the plurality of strong signal time zones corresponding to the plurality of correlation peak positions included in the correlation peak set is the interval between the time zone corresponding to the reference signal L and the time zone corresponding to the reference signal R. Is. Here, there is a correspondence relationship between the correlation peak position L (R) and the time zone corresponding to the reference signal L (R).
The first interference range is a range determined from the first threshold value described later, and is a range indicating that the relative speed is abnormal. The velocity of the transmitted signal around the moving body may be an actual value or an approximate value.
The exclusion unit 126 assumes that the object 2 actually exists and that the object 2 reflects the transmitted wave 3, regardless of whether or not the object 2 actually exists around the moving body. The exclusion unit 126 calculates the Doppler shift rate caused by the object 2 using the received signal, and it is assumed that the object 2 does not exist when the calculated Doppler shift rate is abnormal.

The distance calculation unit 127 calculates the distance from the vehicle 1 to the object 2 using the maximum peak. The object 2 may also refer to an assumed object.

The velocity calculation unit 128 calculates the relative velocity using the maximum peak. The calculated relative speed is transmitted to a subsequent module (not shown) together with the distance calculated by the distance calculation unit 127. The relative speed is the relative speed between the vehicle 1 and the object 2 unless otherwise specified. Specific examples of the latter-stage module are a vehicle control ECU, an alarm device ECU, and the like.

*** Explanation of operation ***
The operation procedure of the detection device 100 corresponds to the detection method. Further, the program that realizes the operation of the detection device 100 corresponds to the detection program.

FIG. 5 is a flowchart showing an example of the operation of the detection device 100.
The operation of the detection device 100 will be described with reference to this figure.

(Step S1: Transmission process)
The transmitter 123 causes the transmitter 106 to transmit a transmission signal. The transmission unit 123 typically uses a pair pulse wave, which will be described later, as the transmission signal.

(Step S2: Synchronous processing)
The synchronization unit 121 synchronizes the transmission start time with the storage start time. The transmission start time is also the time when the transmission unit 123 starts the process of step S1.
In order to carry out the process of this step, the synchronization unit 121 may read the waveform of the transmission signal stored in the memory 103, or may acquire the waveform of the transmission signal sequentially created by the transmission unit 123. ..
After the processing of the synchronization unit 121 is completed, the reception unit 124 receives the signal received by the receiver 107 as a reception signal, and transmits the reception signal to the object detection unit 122.
Further, the receiving unit 124 receives the reference signal from the transmitting unit 123 and transmits the received reference signal to the object detection unit 122.

(Step S3: Detection process)
The object detection unit 122 performs the detection process using the received signal. Details of the processing in this step will be described later.

(Step S4: Transmission processing)
_{The object detection unit 122 transmits the distance d I, J} from the vehicle 1 to the object 2 calculated in step S3 and _{the relative speed v I, J of} the object 2 to the subsequent module as a detection result.

If no set of peak candidates is selected in step S106, that is, if there is no peak candidate that satisfies the criteria, the object detection unit 122 may determine that the correlation peak corresponding to the reflected wave 4 does not exist. good. In this case, the object detection unit 122 may transmit to the subsequent module that the object was not detected, or that the distance and the relative velocity are invalid values.

The detection device 100 repeatedly performs the processes shown in this flowchart at intervals of transmission.
As a specific example, the detection device 100 uses a cycle time as a transmission interval.
The detection device 100 may not always continue to perform the processing of this flowchart at equal intervals, and may change the transmission interval according to the situation of the vehicle 1. As a specific example, the detection device 100 may change the transmission interval according to the speed of the vehicle 1, such as when the vehicle is stopped, when the vehicle is traveling at a low speed, or when the vehicle is traveling at a high speed.
As another specific example, the detection device 100 shortens the transmission interval when it is necessary to detect an object at a short interval, and increases the transmission interval in other cases, depending on the surrounding conditions of the vehicle 1. The transmission interval may be changed.
The detection device 100 may change the interval according to the sensing area, and as a specific example, widen the transmission interval when sensing an object 2 located at a long distance. This is because the detection device 100 needs to prevent the reflected wave 4 and the transmission signal from being associated with each other by starting the transmission of the next transmission signal before receiving the reflected wave 4.
However, when the characteristics of the transmission signal are changed in a plurality of patterns each time it is repeated, the detection device 100 does not necessarily have to make the transmission interval wider than the time required for receiving the reflected wave 4. The sensing area is an area that the detection device 100 is sensing to detect the object 2.
There may be a time zone in which the detection device 100 does not transmit the transmission signal (the processing of this flowchart is not performed).

FIG. 18 shows an example of a pair pulse wave. The transmission signal transmitted by the transmission unit 123 will be described with reference to this figure.
The horizontal axis shown in this figure is the time axis. As shown in this figure, the pair pulse wave is the left wave yL = x (-t), (-t2≤t≤-t1) and the right wave yR = x (t), (t1≤t≤t2). It is yL + yR which added up. The wave on the left and the wave on the right are axisymmetric with respect to the axis of symmetry. The axis of symmetry is the axis that passes through the origin of the time axis and is perpendicular to the time axis. Hereinafter, unless otherwise specified, when referring to each pair pulse wave, it is assumed that each pair pulse wave is arranged so as to be axisymmetric with respect to the axis of symmetry. t1 is used as a symbol indicating the start time of yR, and t2 is used as a symbol indicating the end time of yR. The values of t1 and t2 are not fixed and are determined according to the corresponding pair pulse wave.
yL is called a pair pulse L and yR is called a pair pulse R. A pair of pair pulse L and pair pulse R is called a pair pulse LR. The signals corresponding to the pair pulse L and the pair pulse R in the transmission signal are referred to as a reference signal L and a reference signal R, respectively.

FIG. 15 shows an example of the characteristics of the signal used in this embodiment.
The signal used by the detection device 100 is a pair pulse wave created by using a wave having a property that the correlation peak position L (R) shifts according to the Doppler shift. The correlation peak position L (R) is a position corresponding to the peak (correlation peak L (R)) of the cross-correlation function between the received signal and the reference signal L (R), and is a position on the time axis. The correlation peak L (R) indicates a peak corresponding to the reflected wave 4 and the reference signal L (R) unless otherwise specified.
The detection device 100 has a required interval between the end of the transmission of the pair pulse L and the start of the transmission of the pair pulse R. The required interval is the minimum required pair pulse interval. The pair pulse interval is the interval from the end of the pair pulse L to the start of the pair pulse R, that is, the time from −t1 to t1. The detection device 100 may determine the required interval in any way.
The detection device 100 uses "a wave in which a wave having a property that the correlation peak position shifts according to the Doppler shift is arranged line-symmetrically with respect to the target axis, and the pair pulse interval is equal to or longer than the required interval". Hereinafter, this wave is referred to as a "normal pair pulse wave".
Hereinafter, when the transmitted wave 3, the reflected wave 4, or the direct wave 5 is referred to, it refers to a pair of pulse waves unless otherwise specified.

A pair pulse wave usually consists of a left reference signal in which a right reference signal is arranged. The right reference signal is reflected when the relative velocity between the moving object and the existing object is not 0 when the received signal includes a reflected signal corresponding to the transmitted signal reflected by the existing object existing around the moving object. The correlation peak position is shifted according to the Doppler shift that occurs in the signal. The right reference signal has a time zone in which the amplitude is not 0 from time t1 to time t2 when t1 and t2 are positive values on the time axis and t1 <t2, and the amplitude is 0 at other times. Is. The left reference signal is a signal having a symmetry axis passing through t0 when t0 is set to a value smaller than t1, and the right reference signal is arranged line-symmetrically with respect to a target axis perpendicular to the time axis. The right reference signal is synonymous with the reference signal R. The left reference signal is synonymous with the reference signal L.

The exclusion unit 126 calculates the Doppler shift rate using the distance between the right side reference signal and the left side reference signal and the difference between the correlation peak position corresponding to the right side reference signal and the correlation peak position corresponding to the left side reference signal.

In FIG. 15, the upper row shows the case where the relative speed is 0, and the lower row shows the case where the relative speed is not 0. By comparing the upper and lower rows, the properties of normal pair pulse waves will be explained.
In the situation of FIG. 1, since the direct wave 5 reaches the receiver 107 without being reflected by the object 2, no Doppler shift occurs in the direct wave 5 regardless of the relative velocity. Further, the receiver 107 directly receives the wave 5 after a delay from the time when the transmitter 106 transmits the transmission wave 3 for the time corresponding to the distance between the transmitter 106 and the receiver 107. Note that FIG. 15 shows an example in which the distance between the transmitter 106 and the receiver 107 is short, and the delay according to the distance between the transmitter 106 and the receiver 107 is almost zero.
The reflected wave 4 has an amplitude attenuation due to air propagation. Further, when the relative velocity of the object 2 is not 0, the waveform of the reflected wave 4 expands and contracts due to the Doppler shift generated according to the relative velocity.
When a Doppler shift occurs, the correlation peak position L and the correlation peak position R shift. Normally, due to the symmetry of the waveform of the pair pulse wave, the amount of shift of the correlation peak position R is equal to the amount of shift of the correlation peak position L, and the direction in which the correlation peak position R shifts is opposite to the direction in which the correlation peak position L shifts. Is.
The detection device 100 usually uses the properties of the pair pulse wave to calculate the relative velocity and discriminate between the interference wave 7 and the reflected wave 4. Details will be described later.

Normally, the pair pulse wave may be any wave as long as it satisfies the above-mentioned property, and is not limited to a specific wave.

FIG. 17 shows a tan step multicarrier wave, which is a kind of multicarrier wave, as an example of a normal pair pulse wave. Here, the multi-carrier wave is a wave formed by superimposing waves (carriers) having different frequencies, as shown in [Equation 1]. Here, q is the number of carriers, f _k is the frequency of each carrier, φ _k is the initial phase of each carrier, and a _k is the maximum amplitude of each carrier.

Function shown in FIG. 17, by associating _{(φ k = 2πf k T 0} ) an initial phase phi _k for each carrier _{f k} at _{f k} and 1-to-1, when each carrier due to the Doppler shift is shifted, It is a function in which the correlation peak is likely to appear. However, the detection device 100 does not necessarily have to use the function in which the initial phase is set in this way.
_{FIG. 17 shows an example in which f k} is changed to a function using the tan function for k in the multi-carrier equation shown in [Equation 2]. Here, T ₀ represents a coefficient representing the magnification of f _k and φ _k.

As a specific example, if the tan curve such that the resonant frequency _{f m} of the transmitter 106 in the case where the _{f k} was k = (q-1) / 2, so that [Expression 3]. When [Equation 3] is rearranged using [Equation 4], it becomes [Equation 5]. By adjusting the parameter a, [Equation 5] becomes a function having the characteristics of a normal pair pulse wave. Here, f _w represents a half-bandwidth (f _w = f _m − f ₀ ).

As a specific example, the detection device 100 _{creates a multi-carrier wave (called a tan step multi-carrier wave) using f k,} and uses a waveform cut out with a certain time width t1 ≦ t ≦ t2 as a reference signal R. A normal pair pulse wave in which a waveform symmetric to the reference signal R is arranged line-symmetrically with respect to the target axis as the reference signal L is used as the transmission signal.

The detection device 100 may use a wave other than the tan step multicarrier wave, and as a specific example, a normal pair pulse wave of the log step multicarrier wave described in Reference 1 may be used. In the mathematical formula corresponding to the log step multi-carrier wave, f _k of [Equation 2] is used as an exponential function with respect to k as shown in [Equation 6] (p represents a bandwidth).

[Reference 1]
Japanese Unexamined Patent Publication No. 2015-17942

The detection device 100 includes a pair of up-charp wave and down-charp wave, a pair of down-charp wave and up-charp wave, an error function step multicarrier wave (corresponding to _{f k using an err function). What are the constants of f k} (a, b, c) using the tanh step multicarrier wave ( _{corresponding to f k} using the tanh function) and the 1-inverse proportional step multicarrier wave (ab / (k + c))? (May be)), Harmonic series step multicarrier wave ( _{corresponds to f k} using harmonic series), Approximate harmonic series step multicarrier wave (corresponds to _{f k using approximate harmonic series),} Equal step multi-carrier wave ( _{corresponds to f k} using an equal difference series), step difference equal step multi-carrier wave ( _{corresponds to f k} using a series in which the series of series is an equal series), or floor Difference quadratic function A normal pair pulse wave generated by using a _{step multicarrier wave (corresponding to fk} using a series whose series of series is a quadratic function) may be used.
The normal pair pulse wave created from the pair of the up chirp wave and the down chirp wave corresponds to the pair pulse wave described in Patent Document 1 when the pair pulse interval is 0.
The detection device 100 can use a normal pair pulse wave generated by using a wave having a property that the correlation peak position shifts according to the Doppler shift as a transmission signal.

FIG. 16 will explain a phenomenon that occurs when an interference wave 7 is received when a normal pair pulse wave is used as a transmission signal. FIG. 16 shows a situation in which the object 2 does not exist, that is, a situation in which the reflected wave 4 does not exist, for the sake of simplicity.
Here, the direct wave 5 is generated regardless of the reflected wave 4 and the interference wave 7.

In FIG. 16, the interference source 6 transmits a tone burst wave (a signal obtained by continuously transmitting a sine wave for a certain period of time) composed of frequencies included in the frequency band of the transmission wave 3, and the receiver 107 transmits the tone burst wave. An example of the case where the wave is received as the interference wave 7 is shown. As shown in the upper part of this figure, when the relative speed is 0, when the detection device 100 receives the interference wave 7, the bands of the transmission wave 3 and the interference wave 7 overlap, so that the signal is referred to as the reception signal. When the cross-correlation function with the signal is obtained, the correlation peak appears at the position corresponding to the interference wave 7. That is, the correlation peak position L and the correlation peak position R substantially coincide with each other.
On the other hand, as shown in FIG. 15, regarding the correlation peak corresponding to the reflected wave 4, since the correlation peak position L (R) follows the pair pulse L (R), the correlation peak position L and the correlation peak position R do not match. ..
Therefore, the correlation peak corresponding to the reflected wave 4 and the correlation peak corresponding to the interference wave 7 have different properties from each other. The detection device 100 utilizes this difference in properties to remove the interference wave 7.

As shown in the lower part of FIG. 16, when the relative velocity is not 0, that is, when the Doppler shift occurs and the interference wave 7 expands and contracts, the correlation peak position L and the correlation peak position R are the same as when the relative velocity is 0. Is almost the same as. Therefore, the detection device 100 can remove the interference wave 7 as in the case where the relative speed is 0.

Correlation corresponding to the interference wave 7 even when the interference wave 7 is a chapter wave, a coded signal (for example, a Barker code, a Gold code, an amplitude modulation, a phase modulation, or a frequency-modulated tone burst wave in the M series). Correlation peaks that are peaks and have the properties shown in FIG. 16 appear. Therefore, the detection device 100 can remove the interference wave 7 in the same manner as when the interference wave 7 is a tone burst wave.

When the interference wave 7 is a noise or signal having a frequency band different from that of the transmission wave 3, the correlation peak does not appear or hardly appears. Therefore, in this case, the detection device 100 removes the interference wave 7 by performing a normal process (for example, a process of determining that the correlation peak value is equal to or less than a predetermined threshold value and removing it). Can be done. The normal processing is not limited to the above-mentioned example, and the detection device 100 may select any processing as the normal processing.

FIG. 6 is a flowchart showing an example of the operation of the detection process of the object detection unit 122 according to the present embodiment. The operation of the object detection unit 122 will be described with reference to this figure.

The peak candidate detection unit 125 carries out the processing of step S101 and step S102.

(Step S101: Correlation calculation process)
The peak candidate detection unit 125 calculates the cross-correlation function ΦL of the received signal and the reference signal L and the cross-correlation function ΦR of the received signal and the reference signal R. Here, if the received signal is r (t) and the reference signal is s (t), the cross-correlation function Φ is expressed as [Equation 7] (τ represents a lag). [Equation 7] is a cross-correlation function for continuous time. The detection device 100 can also handle a cross-correlation function for discrete time.

(Step S102: Peak candidate detection process)
Peak candidate detecting section 125, for each of the ΦL and ΦR calculated in step S101, the peak candidate set _{{P L (k L)}} , to detect and _{{P R (k R)}} . The peak candidate indicates a correlation peak that is a candidate for the maximum peak.
The peak candidate set is data that summarizes information on the position (elapsed time from the transmission start time) and the amplitude for each peak candidate.
Peak candidate set, as a specific example, if the peak candidates are present _{three, {P L (k L)} } = {P L (1), P L (2), P L (3)} = {(p _{It is written as L} (1), _mL (1)), (p _L (2), _mL (2)), (p _L (3), _mL (3))}. p _L (k) (k = 1, 2, 3) represents the peak position, and _mL (k) represents the peak amplitude. Hereinafter, _{the unit of p L} (k) is a unit representing the elapsed time. The p _R and _{m R,} is the same as the _{p L} and _{m L,} respectively.

The peak candidate detection unit 125 may detect the peak candidate by any method. As a specific example, the envelope is obtained for the absolute value of ΦL (envelope detection), and the position where the envelope takes the maximum value. Is used as a peak candidate.
The peak candidate detection unit 125 is a method of limiting the interval of the peak search, a method of excluding peaks whose amplitude is less than or equal to the threshold value, a method of collecting peak candidates having close positions, or an amplitude difference from the minimum values before and after. A method of excluding candidates based on the positional difference may be used.

The exclusion unit 126 carries out the processes from step S103 to step S106. Excluding unit 126, the processing from step S103 to step S105, each _{(k L = i, k R} = j) combinations performed on _{(P L (i), P} R (j)). The exclusion unit 126 may use a mathematical formula other than the mathematical formula shown in the specific example. A set of _{(P L (i), P} R (j)), is denoted as _{P i, j.}
Excluding unit 126, as a specific example, if the elements of the peak candidate set is two by _{two, P 1,1, P 1,2, P} 2,1, performs the processing of the four patterns of _{P 2, 2.}
However, the exclusion unit 126 does not necessarily have to perform processing on all patterns, and a set for performing processing may be appropriately selected.
Excluding unit 126, as an example, by utilizing the fact that the normal Peaparusu wave Peaparusu L, the correlation peak position of the reflected wave 4 to be transmitted in the order of Peaparusu R becomes L, in the order of R to be used as a transmission signal, p _L (I) _{Only the set satisfying <p R} (j) is selected and processed. The exclusion unit 126 may further limit the set to be processed based on the pair pulse interval of the transmitted wave 3 or the reflected wave 4.

(Step S103: shift rate calculation process)
Excluding unit _{126, P i, j} to calculate the Doppler shift rate [rho _{i, j} for. The Doppler shift rate is a frequency change rate based on the case where there is no Doppler shift. When the frequency without Doppler shift is f and the frequency after Doppler shift is f', ρ _{i, j} = f'/ f. _{That is, ρ i, j} = 1 when the reflected wave 4 does not shift _{, ρ i, j} <1 when the reflected wave 4 shifts to the low frequency side, and the reflected wave 4 shifts to the high frequency side. In the case, ρ _{i, j} > 1.

The exclusion unit 126 may calculate the Doppler shift rate by any method. The calculation method of the exclusion unit 126 may be changed depending on the type of the normal pair pulse wave used by the exclusion unit 126.
As a specific example, when the detection device 100 uses a normal pair pulse wave composed of the above-mentioned log step multicarrier wave as a transmission signal, the exclusion unit 126 approximately calculates the Doppler shift rate as in [Equation 8]. Here, T _I denotes the Peaparusu interval of the transmitted wave 3. That is, when there is no Doppler _{shift, p R (j) -p L} (i) = T I is holds a ρ _i, j = 1.

As a specific example, the exclusion unit 126 is a set of a down chirp wave whose frequency linearly decreases _{from f 1} to f ₀ and an up chirp wave whose frequency linearly increases from f _{0 to f 1} (these are set with respect to the time axis origin). When the detection device 100 uses a normal pair pulse wave composed of (waveforms arranged symmetrically) as a transmission signal, the Doppler shift rate is approximately calculated as in [Equation 9]. Here, T represents the required time (sweep time) until the _{frequency changes from f 1} to f ₀ , or from f ₀ to f _1. That is, when there is no Doppler _{shift, p R (j) -p L} (i) = T I is holds a ρ _i, j = 1.

(Step S104: Relative velocity calculation process)
Excluding unit 126, by using the [rho _{i, j} calculated in step S103, the relative velocity _{v i,} to calculate the _j. The exclusion unit 126 may calculate the relative velocity by any method, and as a specific example, the relative velocity is approximately calculated as shown in [Equation 10]. Here, _{v s} represents the speed of sound.
The exclusion unit 126 may use a fixed value (for example, 340 m / s) as _{the speed of sound vs. s.} The exclusion unit 126 may use the speed of sound at the average air temperature in the environment in which the vehicle 1 is used. The exclusion unit 126 installs a temperature sensor (not shown) for measuring the outside air temperature in the vehicle 1, and the control device 101 receives the outside air temperature information acquired by the temperature sensor via the bus 111, and uses the outside air temperature information as the outside air temperature information. The sound velocity may be appropriately corrected based on the above. The exclusion unit 126 may receive the outside air temperature information by communication with the outside and appropriately correct the sound velocity based on the outside air temperature information.

(Step S105: Interference wave determination process)
Excluding unit 126, if _{v i} calculated in step _{S104, j} is within the non-interference _range, it is determined that _{P i, j} does not correspond to the interference wave 7. In other cases, the exclusion unit 126 determines that it corresponds to the interference wave 7. _{Pi and j} corresponding to the interference wave 7 indicate the correlation peak corresponding to the object 2.
The non-interference range is a range in which the exclusion unit 126 determines that the interference wave 7 does not correspond to the interference wave 7, and is a range determined by the first threshold value. The range that is not the non-interference range is called the interference range.
The first threshold value is a value used by the exclusion unit 126 to detect the interference wave 7, and may be composed of a plurality of threshold values. As a specific example, the lower limit is -30 km / h and the upper limit is 30 km / h. The first threshold is typically stored in memory 103 before the start of processing in this step.
The exclusion unit 126 may use a given value as the first threshold value, or may appropriately set the first threshold value according to the speed range to be sensed, the performance of the ultrasonic sensor, the specifications of the vehicle 1, and the like. good.

Here, the relative velocity with respect to the reflected wave 4 will be described with reference to FIG.
As shown in this figure, when the relative velocity of the object 2 is 0, the Doppler shift does not occur in the reflected wave 4, and the difference between the correlation peak position L and the correlation peak position R (p _R (j) −p _L (i). )) Corresponds to the pair pulse interval of the transmitted wave 3. That is, the route length L and the route length R coincide with each other. Further, when the relative velocity of the object 2 is not 0, a Doppler shift occurs in the reflected wave 4, and a difference according to the relative velocity occurs between the path length L and the path length R. The path length L (R) is the time from the transmission start time of the pair pulse L (R) to the appearance of the correlation peak L (R), and is from the correlation peak position corresponding to the direct wave 5 and the reference signal L (R). It is also the time corresponding to the peak position corresponding to the reflected wave 4 and the reference signal L (R).

The relative velocity with respect to the interference wave 7 will be described with reference to FIG.
As shown in this figure, with respect to the interference wave 7, the correlation peak position L and the correlation peak position R substantially coincide with each other regardless of the velocity of the object 2. Therefore, the difference between the path length L and the path length R substantially coincides with the pair pulse interval of the transmitted wave 3. That is, with respect to the interference wave 7, a relative velocity according to the pair pulse interval of the transmission wave 3 is generated.
Therefore, if the pair pulse interval is set to a certain extent, the relative velocity shown in [Equation 10] becomes very large, and becomes a value far outside the range of the first threshold value.

Therefore, the detection device 100 can be utilized for removing the transmission signal having the pair pulse interval such that the relative velocity according to the pair pulse interval is out of the range of the first threshold value, as the outlier of the interference wave 7.
When the detection device 100 uses such a transmission signal, the exclusion unit 126 can distinguish between the interference wave 7 and the reflected wave 4 in one transmission / reception using the first threshold value.

When a plurality of objects 2 are present around the vehicle 1, a plurality of reflected waves 4 may be present regardless of whether or not the interference wave 7 is present.
The exclusion unit 126 calculates an erroneous relative velocity when the pair pulse L corresponding to the reflected wave 4 from the object 2_1 and the pair pulse R corresponding to the reflected wave 4 from the object 2_1 are erroneously paired (mispairing). do. However, the exclusion unit 126 may be able to exclude an erroneous relative velocity by the processing of this step. This is because when the apparent relative velocity is out of the threshold range due to mispairing, the exclusion unit 126 removes the mispaired pair. The object 2_1 and the object 2_2 are notations for distinguishing a plurality of objects 2.

(Step S106: Peak selection process)
Hereinafter, in the description of this flowchart _{, Pi and j} indicate peak candidates determined not to correspond to the interference wave 7 in step S105 unless otherwise specified.
The exclusion unit 126 selects the set having the maximum peak, that is, the maximum amplitude, among the _{Pi and j} determined not to be the interference wave 7 in step S105. A set of peaks candidate corresponding to the maximum peak is denoted as _{(P L (I), P} R (J)).
The exclusion unit 126 may select the maximum peak in any way, and as an example, a set having the maximum amplitude average value ( _mL (i) + m _{R (j)) / 2 among Pi and j is selected.} Select as the maximum peak.
Further, in order to prevent erroneous detection of noise peaks and the like, the exclusion unit 126 _{may be excluded from the candidates for the maximum peak when either mL} (i) or m _R (j) is equal to or less than a predetermined threshold value. good. The exclusion unit 126 may select the maximum peak by paying attention to the larger amplitude of _mL (i) and m _{R (j).}

(Step S107: Distance calculation process)
Distance calculation unit _127, by using the _{(P L (I), P} R (J)), and calculates the distance _{d I, J} from the vehicle 1 to the object 2.
The distance calculation unit 127 may calculate the distances d _{I and J} in any way, and as an example, the route lengths l _{I and J} are calculated as in [Equation 11]. The path lengths l _{I and J} are the sum of the distance from the transmitter 106 to the object 2 and the distance from the object 2 to the receiver 107.
Here, in [Equation 11], the center of the pair pulse LR of the transmitted wave 3 is set as the origin of the time axis. If the origin and thus, the average of the path length _{L = p L (I) +} T I / 2, the path length _R = p R (J) for expressed as _-T I / 2, the path length L and the path length R When the value is calculated, the Doppler shifts corresponding to the pair pulse L and the pair pulse R of the reflected wave 4 are offset.

In the distance calculation unit 127, since the path lengths l _{I and J} are approximately twice the distance from the transmitter 106 to the object 2, the distance from the transmitter 106 to the object 2 is approximately calculated as in [Equation 12]. You may calculate. In [Equation 12], the unit is converted into the unit of distance by multiplying _{the speed of sound vs. s.}

(Step S108: Speed calculation process)
Speed calculation unit _128, by using the _{(P L (I), P} R (J)), calculates the relative speed between the vehicle 1 and the object 2.
The velocity calculation unit 128 may calculate the relative velocity in any way. As an example, the Doppler shift rate ρ _{I, J} is obtained using [Equation 8], and ρ _{I, J} and [Equation 10] are used. Relative velocity v _{I, J} is obtained.

*** Explanation of the effect of Embodiment 1 ***
As described above, according to the present embodiment, the detection device 100 uses a signal corresponding to the pair pulse wave as the transmission signal. Then, the exclusion unit 126 can distinguish between the interference wave 7 and the reflected wave 4 based on the threshold value corresponding to the pair pulse interval even when a plurality of correlation peaks appear in the cross-correlation function.

*** Other configurations ***
<Modification 1>
In this modification, the exclusion unit 126 calculates the Doppler shift rate using the velocity information of the moving body.
FIG. 7 is a flowchart showing an example of the operation of the detection process of the object detection unit 122 according to this modification.
The difference between this figure and the flowchart shown in FIG. 6 will be described.

(Step S110: Speed acquisition process)
The object detection unit 122 acquires the speed information of the vehicle 1 from the vehicle speed ECU 110 via the bus 111.

(Step S104-1: Relative velocity calculation process)
The Doppler shift rate ρ _{i, j} calculated in step S103 and the speed _{vo of the} vehicle 1 can be expressed as [Equation 13]. The exclusion unit 126 obtains _{vi, j} by solving [number 13] for vi _{, j.}
It should be noted that the [number 10], approximated by the [number _{13] (v s ^ 2)} »(v 0 ^ 2), v s v i, j »v o v i, j, v i, for _j solution Corresponds to the formula when there is.

(Step S108-1: Speed calculation process)
The speed calculation unit 128 calculates the relative speed by performing the same processing as the processing in step S108 using the speed of the vehicle 1.

Therefore, according to this modification, since the object detection unit 122 does not use the approximate expression but uses the speed information of the vehicle 1 acquired from the vehicle speed ECU 110, it is possible to calculate the relative speed with higher accuracy.

<Modification 2>
In this modification, the exclusion unit 126 does not calculate the relative velocity, and determines that the correlation peak corresponds to the object 2 when the value of the Doppler shift rate is not the value of the second interference range. The second interference range is a range determined by the second threshold value described later, and is a range indicating that the Doppler shift rate is abnormal.
FIG. 8 is a flowchart showing an example of the operation of the detection process of the object detection unit 122 according to this modification.
The difference between this figure and the flowchart shown in FIG. 6 will be described.

The exclusion unit 126 does not perform the process of step S104.

(Step S105-1: Interference wave determination process)
The exclusion unit 126 _{does not determine whether or not the vi and j} calculated in step S104 are within the range of the first threshold value. The exclusion unit 126 determines whether or not the correlation peak corresponds to the interference wave 7 by determining whether or not the Doppler shift rates ρ _{i and j calculated in step S103 are within the range determined by the second threshold value.}
Second threshold value, the first threshold is a threshold for the relative speed is a threshold that is converted to a value related to a Doppler shift rate, as a specific example, [Expression 10], the to v _{i, j} such [Expression 13] 1 It is obtained by substituting the threshold value and solving for _{ρ i and j.}
In particular, when the exclusion unit 126 uses the approximate calculation formula, the speed information of the vehicle 1 is not used when calculating the second threshold value, so that the memory 103 stores the second threshold value before the processing of this step is performed. May be.

Therefore, according to this modification, the detection device 100 can reduce the processing amount because the step S104 for calculating the relative speed for _{each Pi and j is omitted.}

<Modification 3>
The detection device 100 may quantize the reference signal L and the reference signal R in advance and store them in the memory 103. The detection device 100 may quantize the reference signal in any way, and as specific examples, it is ternated to +1,0, -1, and quintupled to +2, +1,0, -1, -2. Alternatively, it is quantized into an integer type 8 bits.
In this modification, the peak candidate detection unit 125 calculates the cross-correlation function between the received signal and the quantized reference signal.
According to this modification, the size of the reference signal stored in the memory 103 can be reduced, and the amount of calculation in the process of calculating the cross-correlation function can be reduced.

The detection device 100 may quantize not only the reference signal but also the received signal. The peak candidate detection unit 125 may calculate a cross-correlation function between the quantized received signal and the quantized reference signal.
The detection device 100 can further reduce the processing amount by quantizing the received signal as well.

<Modification example 4>
The receiving unit 124 may ignore the direct wave 5 and consider that the reference signal is received at the transmission time when the transmitting unit 123 transmits the transmitting wave 3. In this modification, as a specific example, the receiving unit 124 determines whether or not the received signal corresponds to the direct wave 5 based on the transmission time and the reference wave, and corresponds to the direct wave 5 from the received signal. Delete the signal and add the reference signal to the received signal in consideration of the transmission time.

<Modification 5>
In this embodiment, the case where each functional component is realized by software has been described. However, as a modification, each functional component may be realized by hardware.

When each functional component is realized by hardware, the detection device 100 includes an electronic circuit 16 instead of the processor 11. Alternatively, although not shown, the detection device 100 includes an electronic circuit 16 in place of the processor 11, the main storage device 12, and the auxiliary storage device 13. The electronic circuit 16 is a dedicated electronic circuit that realizes the functions of each functional component (and the main storage device 12 and the auxiliary storage device 13). Electronic circuits are sometimes called processing circuits.

The electronic circuit 16 is assumed to be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programbulable Gate Array). Will be done.

Each functional component may be realized by one electronic circuit 16, or each functional component may be distributed and realized by a plurality of electronic circuits 16.

Alternatively, some functional components may be realized by hardware, and other functional components may be realized by software.

The processor 11, the main storage device 12, the auxiliary storage device 13, and the electronic circuit 16 described above are collectively referred to as "processing circuit Lee". That is, the function of each functional component is realized by the processing circuit.

Embodiment 2.
In the present embodiment, the object detection process in the detection device 100 and the content of the detection result are different from those in the first embodiment.
Hereinafter, the differences between the present embodiment and the first embodiment will be described.

*** Explanation of configuration ***
Although not shown, the detection device 100 includes an object detection unit 122b instead of the object detection unit 122.

FIG. 9 shows an example of a functional block diagram of the object detection unit 122b. As shown in this figure, the object detection unit 122b does not include the exclusion unit 126, but includes the exclusion unit 126b and the result selection unit 129.

*** Explanation of operation ***
FIG. 10 is a flowchart showing an example of the operation of the detection device 100.
The detection device 100 carries out the process of step S3b instead of step S3, and carries out the process of step S4b instead of step S4.

(Step S3b: Detection process)
The object detection unit 122b performs detection processing using the received signal. Details of the difference between the processing of this step and the processing of step S3 will be described later.

(Step S4b: Transmission processing)
The object detection unit 122b transmits the set of N sets of detection results selected in step S3b to the subsequent module.

FIG. 11 is a flowchart showing an example of the operation of the detection process of the object detection unit 122b.
The operation of the object detection unit 122b will be described with reference to this figure.

The processing from step S101 to step S105 is the same as that of the first embodiment.
The exclusion unit 126b does not execute the process of step S106, and outputs a set of _{Pi and j determined not to correspond to the interference wave 7 in step S105.}

Distance calculating unit 127, the combination _{P i} of each _{(k L = i, k R} = j), among the _{j, P i} is determined not to correspond to the interference wave 7 at step _S3b, relative to _j, implementation The process of step S107 shown in the first embodiment is carried out.
The speed calculation unit 128 carries out the process of step S108 in the same manner as in step S107.

(Step S109: Result selection process)
The result selection unit 129 is N sets from the set of detection results (di _{, j} , vi _{, j ) of the distance di, j obtained in step S107 and the relative velocities vi, j} obtained in step S108. Select (N is an integer).
The result selection unit 129 may select any set of detection results, and as an example, N sets of detection result sets are selected in order of proximity (or distance). This example is effective, for example, when there are a plurality of objects 2 around the vehicle 1, and the object at a short distance (or a long distance) is preferentially detected.
As another example, the result selection unit 129 preferentially selects the object 2 whose relative velocity is (or is) equal to or less than the threshold value. This example is effective when, for example, a moving object (or a stationary object) is preferentially detected.
As another example, the result selection unit 129 _{collectively groups groups with close distances di and j} , and then selects one set of peak candidates from each group. According to this example, for example, when a plurality of objects 2 exist around the vehicle 1, the number of reflected waves 4 from the object 2 of 1 is reduced. Therefore, according to this example, the result selection unit 129 can detect the reflected wave 4 from as many objects 2 as possible.
As another example, the result selection unit 129 _{groups groups with close distances di and j} together, and then the relative speed detection results of the sets included in the group vary by a threshold value or more (for example, relative speed). If the variance of is greater than or equal to the threshold value), the group is excluded, or the group is divided again so that the variation in relative velocity becomes small. According to this example, since the group in which the speed variation is large even if the distance is short is not handled, the group in which the false detection is likely to be included can be excluded. Therefore, according to this example, the result selection unit 129 can distinguish between the group of reflected waves 4 corresponding to a stationary object and the group of reflected waves 4 corresponding to a moving object.

*** Explanation of the effect of Embodiment 2 ***
As described above, according to the present embodiment, not only the result corresponding to the maximum peak but also the result corresponding to a plurality of correlation peaks can be obtained.
Therefore, according to the present embodiment, when a plurality of objects exist around the vehicle 1, not only the maximum peak from the object 2 having a strong reflection intensity but also the vehicle due to reasons such as being located near the vehicle 1. An object 2 located far away from 1 and an object 2 having a weak reflection intensity can also be detected.

Embodiment 3.
The detection device 100 according to the present embodiment includes a plurality of receivers 107.
Hereinafter, the differences between the present embodiment and the first embodiment will be described.
In the following, for the sake of simplicity, it is assumed that the detection device 100 includes two receivers 107. However, the detection device 100 may include three or more receivers 107.
Hereinafter, in order to distinguish between the two receivers 107, they are referred to as receiver 107-1 and receiver 107-2, respectively.

*** Explanation of configuration ***
Although not shown, the detection device 100 includes an object detection unit 122c instead of the object detection unit 122.

FIG. 12 is an example of a functional block diagram of the object detection unit 122c. The object detection unit 122c includes two peak candidate detection units 125, two exclusion units 126, and two speed calculation units 128, and includes a position calculation unit 130 instead of the distance calculation unit 127.
The receiving unit 124 stores a plurality of received signals.
The exclusion unit 126 obtains the maximum peak having the maximum amplitude among the correlation peaks corresponding to the object 2 for each of the plurality of received signals.
The position calculation unit 130 calculates the position of the object 2 using the plurality of maximum peaks obtained by the exclusion unit 126.

*** Explanation of operation ***
FIG. 13 is a flowchart showing an example of the operation of the detection device 100.
The detection device 100 performs the process of step S2c instead of step S2, the process of step S3c instead of step S3, and the process of step S4c instead of step S4.

(Step S2c: Synchronous processing)
The receiving unit 124 receives the signals from the receiver 107-1 and the receiver 107-2 as a receiving signal. The signal received by the receiving unit 124 from the receiver 107-1 is referred to as a reception signal R1, and the signal received by the receiving unit 124 from the receiver 107-2 is referred to as a receiving signal R2. Hereinafter, in the description of the present embodiment, the notation of the received signal is a general term of the received signal R1 and the received signal R2 unless otherwise specified.
The synchronization unit 121 and the reception unit 124 carry out the process of step S2 using all the received received signals.

(Step S3c: Detection process)
The object detection unit 122 performs the process of step S3 using all the received signals. Details of the difference between the processing of this step and the processing of step S3 will be described later.

(Step S4c: Transmission processing)
The object detection unit 122c transmits the relative position coordinates (x _{I, J} , y _{I, J} ) calculated in step S3c and the relative velocity as the detection result to the subsequent module.
The position calculation unit 130 calculates the distances d _{I and J} when calculating the relative position coordinates. Therefore, the object detection unit 122c may _{transmit the distances d I and J} to the subsequent module.
Further, the object detection unit 122c may _{select all or any of the distance d I, J} , the relative position coordinates, and the relative velocity according to the specifications of the latter stage module and transmit the transmission to the latter stage module. The object detection unit 122c may transmit only one of _{the relative velocities v1 I and J} and the relative velocities v2 _{I and J} calculated in step S108c to the subsequent module.

FIG. 14 is a flowchart showing an example of the operation of the detection process of the object detection unit 122c.
The operation of the object detection unit 122c will be described with reference to this figure.

Each peak candidate detection unit 125 performs processing in step S101 and step S102 using each of the two received signals obtained from the receiver 107-1 and the receiver 107-2.
Each exclusion unit 126 performs processing from step S103 to step S106.
The processing from step S101 to step S106 is the same as that of the first embodiment.
Therefore, each exclusion unit 126 has a maximum peak set ((P _1L (I), P _1R (J)), (P _2L (I), P _2R (J)) of a maximum of one for each received signal. ))) Select. In addition, each exclusion unit 126 does not select the set of maximum peaks when there is no set of peak candidates satisfying a predetermined criterion.
Each speed calculation unit 128 carries out the process of step S108c instead of step S108.

(Step S108c: Speed calculation process)
Each velocity calculation unit 128 uses the relative velocity v1 _{I, J} or _{(P 1L} (I), P _1R (J)) or (P _2L (I), P _{2R (J)) selected in step S106.} Calculate v2 _{I and J.}
Each speed calculation unit 128 performs the same processing as in step S108 to calculate the relative speed.

(Step S111: Position calculation process)
The position calculation unit 130 calculates relative position coordinates using _{(P 1L} (I), P _1R (J)) and (P _2L (I), P _{2R (J)) selected in step S106.} The position calculation unit 130 may calculate the relative position coordinates in any way.
Position calculating unit 130 converts an example, _{l1 I,} and _{J, l2 I,} calculates and _{J, l1} I, J, _{l2 I,} a unit path length multiplied by the sound velocity _{v s} to _J into units of distance do. The path lengths l1 _{I and J} are the sum of the distance from the transmitter 106 to the object 2 and the distance from the object 2 to the receiver 107-1. The path lengths l2 _{I and J} are the sum of the distance from the transmitter 106 to the object 2 and the distance from the object 2 to the receiver 107-2.
As a specific example, the position calculation unit 130 calculates the route lengths l1 _{I and J} and the route lengths l2 _{I and J} by the method shown in step S107.
Here, the memory 103 stores the distance ds1 from the transmitter 106 to the receiver 107-1 and the distance ds2 from the transmitter 106 to the receiver 107-2 before the processing of this step is performed. It shall be.
Therefore, any of the triangle consisting of the transmitter 106, the receiver 107-1 and the object 2 and the triangle consisting of the transmitter 106, the receiver 107-2 and the object 2 The sum of the length of one side and the length of the other two sides is known. Therefore, the position calculation unit 130 performs a three-sided survey on each triangle to obtain the distance from the transmitter 106 to the object 2, the distance from the receiver 107-1 to the object 2, and the receiver 107-. The distance from 2 to the object 2 and the relative position coordinates of the object 2 can be obtained.

*** Explanation of the effect of Embodiment 3 ***
As described above, according to the present embodiment, since the detection device 100 includes a plurality of receivers 107, the relative position coordinates of the object 2 can be calculated.
Therefore, according to the present embodiment, in the detection device 100, there are a plurality of objects 2 around the vehicle 1, the distance between each of the plurality of objects 2 and the vehicle 1 is the same, and the plurality of objects 2 are each a vehicle. A plurality of objects 2 can be distinguished when they are in different directions when viewed from 1.

Embodiment 4.
The detection device 100 according to the present embodiment includes a plurality of transmitters 106 and a plurality of transmitters 123. The transmission unit 123 according to the present embodiment transmits a plurality of transmission signals having different characteristics from each other.
Hereinafter, the differences between the present embodiment and the first embodiment will be described.
In the following, for the sake of simplicity, it is assumed that the detection device 100 includes two transmitters 106. However, the detection device 100 may include three or more transmitters 106.
Hereinafter, in order to distinguish between the two transmitters 106, they are referred to as transmitter 106-1 and transmitter 106-2, respectively.

*** Explanation of configuration ***
Although not shown, the detection device 100 may include a transmitter unit 123-1 corresponding to the transmitter 106-1 and a transmitter unit 123-2 corresponding to the transmitter 106-2. The detection device 100 may include one transmitter 123 and transmit different transmission signals to each transmitter 106.
The transmission unit 123 instructs to transmit a plurality of types of transmission signals corresponding to each of the plurality of types of reference signals.

*** Explanation of operation ***
Before explaining the operation of the present embodiment, the case where the transmitter 106-1 and the transmitter 106-2 have the same type of signal will be described.
When the transmitter 106-1 and the transmitter 106-2 simultaneously transmit the transmission wave 3 having the same characteristics, the characteristics of the reflected wave 4 corresponding to the respective transmitters 106 match, so that the exclusion unit 126 may be used. It is not possible to identify which transmitter 106 is the reflected wave 4. Therefore, in order to detect the reflected wave 4 corresponding to one transmitter 106, the exclusion unit 126 needs to identify the reflected wave 4 (hereinafter, interference reflected wave) corresponding to the other transmitter 106 as the interference wave 7. However, there is a problem that the disturbing reflected wave cannot be identified as the interference wave 7.
When the transmitter 106-1 and the transmitter 106-2 transmit transmission signals at different times, in addition to the above problems, the direct wave 5 from the other transmitter 106 (hereinafter referred to as the interference direct wave). ) May act as an interference wave 7. Although the object detection unit 122 needs to identify the interference direct wave as the interference wave 7, it is difficult to identify the interference direct wave as the interference wave 7.

Hereinafter, the operation of this embodiment will be described.
The transmission signals transmitted by the transmitter 106-1 and the transmitter 106-2 have different characteristics. The transmitter 106 may transmit a normal pair pulse wave having any characteristic.
As an example, the transmitter 106-1 uses a normal pair pulse wave composed of a multi-carrier wave composed of carriers having a frequency fa ≦ f ≦ fb as a transmission signal, and the transmitter 106-2 uses a frequency fc ≦ f ≦ fd (fc ≠ fc ≠). A normal pair pulse wave composed of a multi-carrier wave composed of carriers (satisfying at least one of fa and fd ≠ fb) is used as a transmission signal.
That is, the two types of transmission signals have different frequency bands, or only a part of the frequency bands overlap. Therefore, when the exclusion unit 126 calculates the cross-correlation function in step S101, the correlation peak corresponding to the interference wave 7 does not appear or is small.
Therefore, the exclusion unit 126 can remove the disturbing reflected wave and the disturbing direct wave as the interference wave 7.

As another example, transmitter 106-1 uses a normal pair pulse wave modulated using one code sequence as a transmission signal, and transmitter 106-2 uses a normal pair pulse wave modulated using another code sequence as a transmission signal. Use.
In this example, since the two types of transmitted signals are uncorrelated with each other, the correlation peak corresponding to the interference wave 7 does not appear or is small.
Therefore, the exclusion unit 126 can remove the disturbing reflected wave and the disturbing direct wave as the interference wave 7.

As another example, the transmitter 106-1 and the transmitter 106-2 use two types of normal pair pulse waves having different pair pulse intervals as transmission signals.
In this example, when the cross-correlation function is calculated because the frequency characteristics of the two types of transmission signals match, the correlation peak corresponding to the interference wave 7 appears. However, excluding unit 126, since the Peaparusu interval are different from each other, when the mispairing, in step S104, calculates the different relative speeds v _{i, j} is the case where no mispairing.
Therefore, when the difference between the pair pulse intervals of the two types of transmission signals is such that the exclusion unit 126 determines in step S105 that it corresponds to the interference range, the exclusion unit 126 selects the interference reflected wave and the interference direct wave. , Can be removed as an interference wave 7.

Further, even when a plurality of vehicles 1 having an operating detection device 100 are present around the vehicle 1, the exclusion unit 126 uses the method described above to provide an interference wave 7 from the other plurality of vehicles 1. Can be removed.

*** Explanation of the effect of Embodiment 4 ***
As described above, according to the present embodiment, when the detection device 100 includes a plurality of transmitters 106, the exclusion unit 126 can remove the interference wave 7.
Further, according to the present embodiment, when a plurality of active detection devices 100 are present around the vehicle 1, an interference wave is transmitted from a detection device 100 different from the detection device 100 included in the vehicle 1. It can be removed as 7.

<Modification 6>
The transmitter 123 of 1 may instruct each of the plurality of transmitters 106 to transmit transmission signals different from each other.
The transmitter 106 of 1 may transmit a plurality of types of transmission signals having different characteristics. The transmitter 106 may transmit a plurality of types of transmission signals at the same time, or may transmit each of the plurality of types of transmission signals at different times.

*** Other embodiments ***
It is possible to freely combine the above-described embodiments, modify any component of each embodiment, or omit any component in each embodiment.
Moreover, each modification may be carried out individually, or may be carried out in combination with each other.

Further, the embodiment is not limited to that shown in the first to fourth embodiments, and various changes can be made as needed.

1 vehicle, 2 objects, 3 transmitted waves, 4 reflected waves, 5 direct waves, 6 interference sources, 7 interference waves, 11 processors, 12 main storage devices, 13 auxiliary storage devices, 16 electronic circuits, 19 OS, 100 detectors, 101 controller, 103 memory, 104 communication interface, 105 transmitter amplifier, 106 transmitter, 106-1 transmitter, 106-2 transmitter, 107 receiver, 107-1 receiver, 107-2 receiver, 108 receiver amplifier , 109 vehicle speed sensor, 110 vehicle speed ECU, 111 bus, 112 signal line, 121 synchronization unit, 122 object detection unit, 122b object detection unit, 122c object detection unit, 123 transmitter unit, 123-1 transmitter unit, 123-2 transmitter unit , 124 receiving unit, 125 peak candidate detection unit, 126 exclusion unit, 126b exclusion unit, 127 distance calculation unit, 128 speed calculation unit, 129 result selection unit, 130 position calculation unit, R1 reception signal, R2 reception signal.

Claims (9)

Information corresponding to the time when the transmission signal transmitted from the moving body is transmitted, which corresponds to the reference signal having a plurality of strong signal time zones having a strong signal having a large amplitude and a time zone having a plurality of signals having a small amplitude. A receiver that stores the received signal including
The peak that appears in the cross-correlation function regarding the time lag between each of the strong signals and the received signal is detected, and the peak that does not correspond to the transmitted signal is set as the correlation peak, which is the position on the time axis of the cross-correlation function. A peak candidate detection unit that obtains the relative position of the correlation peak with respect to the position of the peak corresponding to the transmission signal as the correlation peak position.
The Doppler shift rate corresponding to the correlation peak set is calculated using the correlation peak set consisting of the plurality of correlation peak positions and the intervals of the plurality of strong signal time zones corresponding to the plurality of correlation peak positions, respectively, and the Doppler is calculated. Using the shift rate and the velocity of the transmitted signal around the moving object, the relative velocity between the moving object and the object that is assumed to exist around the moving object and corresponds to the correlation peak set is calculated. A detection device including an exclusion unit for determining that the correlation peak set corresponds to the object when the value of the relative velocity is not the value of the first interference range. When the received signal includes a reflected signal corresponding to the transmission signal reflected by the existing object existing around the moving body, the reference signal has a relative speed of 0 between the moving body and the existing object. It is a right-hand reference signal that shifts the correlation peak position according to the Doppler shift that occurs in the reflected signal when it is not, and when t1 and t2 are positive values on the time axis and t1 <t2, the time is from time t1. There is a time zone in which the amplitude is not 0 up to t2, and the right-hand reference signal whose amplitude is 0 at other times, and when t0 is a value smaller than t1, it is the axis of symmetry passing through t0 and the time. It consists of a left reference signal in which the right reference signal is arranged line-symmetrically with respect to a target axis perpendicular to the axis.
The exclusion section uses the distance between the right side reference signal and the left side reference signal and the difference between the correlation peak position corresponding to the right side reference signal and the correlation peak position corresponding to the left side reference signal to perform the Doppler shift. The detection device according to claim 1, wherein the rate is calculated. The detection device according to claim 1 or 2, further comprising a synchronization unit that synchronizes the time when the moving body transmits the transmission signal with the time when the reception unit starts storage of the reception signal. The detection device according to any one of claims 1 to 3, wherein the exclusion unit calculates the Doppler shift rate using the speed information of the moving body. Any of claims 1 to 4, wherein the exclusion unit does not calculate the relative velocity, and determines that the correlation peak corresponds to the object when the value of the Doppler shift rate is not the value of the second interference range. The detection device according to item 1. It is equipped with a position calculation unit that calculates the position of the object.
The receiving unit stores a plurality of received signals, and the receiving unit stores a plurality of received signals.
The exclusion unit obtains the maximum peak having the maximum amplitude among the correlation peaks corresponding to the object for each of the plurality of received signals.
The detection device according to any one of claims 1 to 5, wherein the position calculation unit calculates the position of the object using a plurality of maximum peaks obtained by the exclusion unit. The detection device according to any one of claims 1 to 6, further comprising a transmission unit instructing transmission of a plurality of types of transmission signals corresponding to each of the plurality of types of reference signals. The time at which the transmission signal transmitted from the moving body is transmitted, corresponding to the reference signal in which the receiving unit has a plurality of strong signal time zones having a large amplitude strong signal and a plurality of time zones having a small amplitude signal. It stores the received signal containing the corresponding information and
The peak candidate detection unit detects a peak that appears in the cross-correlation function regarding the time lag between each of the strong signals and the received signal, sets the peak that does not correspond to the transmission signal as the correlation peak, and sets the time of the cross-correlation function. The relative position of the correlation peak to the position of the peak corresponding to the transmission signal, which is a position on the axis, is obtained as the correlation peak position.
The exclusion unit calculates the Doppler shift rate corresponding to the correlation peak set using the correlation peak set consisting of the plurality of correlation peak positions and the intervals of the plurality of strong signal time zones corresponding to the plurality of correlation peak positions. Then, using the Doppler shift rate and the velocity of the transmission signal around the moving body, it is assumed that the object exists around the moving body, and the object corresponding to the correlation peak set is relative to the moving body. A detection method for calculating a velocity and determining that the correlation peak set corresponds to the object when the value of the relative velocity is not a value in the first interference range. The time at which the transmission signal transmitted from the moving body is transmitted, corresponding to the reference signal in which the receiving unit has a plurality of strong signal time zones having a large amplitude strong signal and a plurality of time zones having a small amplitude signal. On a computer that stores a received signal containing the corresponding information,
A peak appearing in the cross-correlation function regarding the time lag between each of the strong signals and the received signal is detected, a peak not corresponding to the transmission signal is set as a correlation peak, and the peak is set as a correlation peak at a position on the time axis of the cross-correlation function. Therefore, the relative position of the correlation peak to the position of the peak corresponding to the transmission signal is obtained as the correlation peak position.
The Doppler shift rate corresponding to the correlation peak set is calculated using the correlation peak set consisting of the plurality of correlation peak positions and the intervals of the plurality of strong signal time zones corresponding to the plurality of correlation peak positions, respectively, and the Doppler is calculated. Using the shift rate and the velocity of the transmitted signal around the moving object, the relative velocity between the moving object and the object corresponding to the correlation peak set, which is assumed to exist around the moving object, is calculated. , A detection program for determining that the correlation peak set corresponds to the object when the value of the relative velocity is not the value of the first interference range.

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