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US-12625260-B2 - Sound wave processing device and ultrasonic system

US12625260B2US 12625260 B2US12625260 B2US 12625260B2US-12625260-B2

Abstract

A sound wave processing device includes a transmission signal generation unit that generates a transmission signal for transmitting a sound wave, a received wave signal output unit that outputs a received wave signal based on receiving the sound wave, a correlation-convolution integral processing unit that performs correlation-convolution integral processing in parallel for each reference wave data, on the basis of the received wave signal and a plurality of reference wave data, and an own wave identification unit that determines whether or not the received sound wave is own wave, which is a reflected wave of the sound wave transmitted by the transmission signal generation unit, on the basis of a correlation-convolution integral value output from the correlation-convolution integral processing unit.

Inventors

  • Takahiro Tsuboi

Assignees

  • ROHM CO., LTD.

Dates

Publication Date
20260512
Application Date
20231208
Priority Date
20210609

Claims (12)

  1. 1 . A sound wave processing device comprising: a transmission signal generation unit that generates a transmission signal for transmitting a sound wave; a received wave signal output unit that outputs a received wave signal based on receiving the sound wave; a correlation-convolution integral processing unit that performs correlation-convolution integral processing in parallel for each reference wave data, on the basis of the received wave signal and a plurality of reference wave data; and an own wave identification unit that determines whether or not the received sound wave is own wave, which is a reflected wave of the sound wave transmitted by the transmission signal generation unit, on the basis of a correlation-convolution integral value output from the correlation-convolution integral processing unit, wherein the own wave identification unit includes a correlation maximum value acquisition unit that acquires a correlation maximum value of the correlation-convolution integral value during a predetermined period for each of the reference wave data, and a determination unit that determines whether or not the received ultrasonic wave is the own wave, on the basis of relative evaluation of the acquired correlation maximum value.
  2. 2 . The sound wave processing device according to claim 1 , wherein the determination unit determines a frequency of the reference wave data at which the acquired correlation maximum value becomes maximum.
  3. 3 . The sound wave processing device according to claim 1 , wherein if frequencies of the reference wave data of three largest of the acquired correlation maximum values are three neighboring frequencies, the determination unit identifies the center frequency of the three neighboring frequencies.
  4. 4 . The sound wave processing device according to claim 1 , further comprising: an envelope detection unit that extracts an envelope of the received wave signal, and a comparator that compares the extracted envelope with a predetermined threshold value, wherein the predetermined period is a period after the envelope exceeds the threshold value until it becomes the threshold value or less.
  5. 5 . The sound wave processing device according to claim 4 , further comprising a band pass filter that extracts a signal in a predetermined band from the received wave signal and outputs the same to the envelope detection unit.
  6. 6 . The sound wave processing device according to claim 1 , wherein the correlation maximum value is a maximum value of absolute values of the correlation-convolution integral values.
  7. 7 . The sound wave processing device according to claim 1 , wherein the transmission signal generation unit performs a plurality of times of transmission, and if the correlation-convolution integral value becomes large at the same frequency of the reference wave data in the plurality of times of transmission, the own wave identification unit determines that the received sound wave is the own wave.
  8. 8 . The sound wave processing device according to claim 1 , wherein the transmission signal generation unit transmits a plurality of sound waves having different frequencies in a continuous manner, and if the frequency of the reference wave data at which the correlation-convolution integral value becomes large is shifted in the same direction by the same amount from the plurality of frequencies, the own wave identification unit determines that the received sound wave is the own wave.
  9. 9 . The sound wave processing device according to claim 1 , further comprising: a first external terminal that enables connection of the transmission signal generation unit to an external ultrasonic wave transmitting/receiving device; and a second external terminal that enables connection of the ultrasonic wave transmitting/receiving device to the received wave signal output unit.
  10. 10 . The sound wave processing device according to claim 1 , which is capable of being mounted on a vehicle.
  11. 11 . An ultrasonic system comprising the sound wave processing device according to claim 9 , and the ultrasonic wave transmitting/receiving device.
  12. 12 . An ultrasonic system capable of being mounted on a vehicle, comprising: a first ultrasonic system including the sound wave processing device according to claim 10 ; and at least one second ultrasonic system other than the first ultrasonic system, wherein the first ultrasonic system and the second ultrasonic system concurrently perform transmission of an ultrasonic wave and TOF (Time Of Flight) measurement.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This nonprovisional application is a continuation application of International Patent Application No. PCT/JP2022/022918 filed on Jun. 7, 2022, which claims priority Japanese Patent Application No. 2021-096559 filed on Jun. 9, 2021, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD The present disclosure relates to a sound wave processing device and an ultrasonic system. BACKGROUND ART Conventionally, there is known an ultrasonic system that measures a distance to an obstacle, by generating a sound wave and measuring time TOF (Time Of Flight) until returning of a reflected wave from the obstacle. Conventionally, this ultrasonic system is usually mounted on a vehicle, and an on-vehicle clearance sonar is known as an example. As an example of this conventional ultrasonic system, there is a system in which waveform data (reference wave data) that is anticipated to be received is prepared, and correlation-convolution integral processing based on the reference wave data and an actually received reception signal is performed, so as to emphasize the reflected wave. This system is also called a pulse compression system, and can improve an S/N ratio. Note that the pulse compression system is described in Patent Document 1, for example. LIST OF CITATIONS Patent Literature Patent Document 1: JP-A-2005-152450 BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically illustrating a vehicle equipped with an ultrasonic system and an object. FIG. 2 is a diagram illustrating an example of correlation processing. FIG. 3 is a diagram illustrating an example of correlation processing. FIG. 4 is a diagram illustrating a structure of a reception processing unit according to a comparative example. FIG. 5A is a diagram illustrating a received wave signal of a simulation result according to the comparative example (the number of samples=128). FIG. 5B is a diagram illustrating correlation-convolution integral values of the simulation result according to the comparative example (the number of samples=128). FIG. 6A is a diagram illustrating the received wave signal of the simulation result according to the comparative example (the number of samples=256). FIG. 6B is a diagram illustrating the correlation-convolution integral values of the simulation result according to the comparative example (the number of samples=256). FIG. 7 is a diagram illustrating a structure of the ultrasonic system according to a first embodiment. FIG. 8 is a diagram illustrating a specific structural example of a correlation processing unit and a correlation processed value summing unit. FIG. 9 is a table showing an example of correlation maximum values. FIG. 10 is a schematic diagram illustrating a situation where the vehicle equipped with the ultrasonic system moves. FIG. 11A is a diagram illustrating the received wave signal of the simulation result according to the comparative example (when the vehicle is stopped). FIG. 11B is a diagram illustrating the correlation-convolution integral values of the simulation result according to the comparative example (when the vehicle is stopped). FIG. 12A is a diagram illustrating the received wave signal of the simulation result according to the comparative example (when the vehicle is moving). FIG. 12B is a diagram illustrating the correlation-convolution integral values of the simulation result according to the comparative example (when the vehicle is moving). FIG. 13 is a diagram illustrating a structure of the ultrasonic system according to a third embodiment. FIG. 14 is a schematic diagram illustrating an example of a vehicle equipped with a plurality of ultrasonic systems. DESCRIPTION OF EMBODIMENTS Hereinafter, an exemplified embodiment is described with reference to the drawings. Note that an ultrasonic system according to the embodiment described below is intended to be mounted on a vehicle as an example, and can be used for a warning function, an automatic braking function, an automatic parking function, or the like, by measuring a distance between the vehicle and an object. <1. Correlation Processing> First, an outline of correlation processing that is used in the ultrasonic system is described. FIG. 1 illustrates a vehicle 500 equipped with the ultrasonic system (not shown) and an object (obstacle) 1000. An ultrasonic wave transmitted from the ultrasonic system is reflected by the object 1000 and is received as a reflected wave by the ultrasonic system. Here, the correlation processing is described with reference to FIGS. 2 and 3. In FIG. 2, reference wave data Dref is prepared in advance. The reference wave data Dref is waveform data of the reflected wave that is assumed to be received, and is waveform data having the same frequency as that of a sound wave that is transmitted. The frequency of a reflected wave Rs1 illustrated in FIG. 2 is the same as the transmitted wave frequency. In other words, the reflected wave Rs1 is own w