Signal processing equipment, sound wave systems, and vehicles

Abstract

This signal processing device includes: a wave-transmission signal generation unit configured so as to generate a wave-transmission signal for wave transmission of a sound wave; a wave-reception signal output unit configured so as to output a wave-reception signal based on the received sound wave; and a reflected wave detection unit configured so as to detect a reflected wave of the wave transmission that may be included in the received wave, on the basis of the wave-reception signal. The wave-transmission signal includes: a first signal having a first predetermined wave number; and a second signal, which is generated after the first signal and has a second predetermined wave number that is smaller than the first predetermined number.

Description

Technical Field

[0001] The invention disclosed in this specification relates to a signal processing device that processes a transmission signal for transmitting sound waves and a reception signal based on reception of sound waves, a sound wave system including the signal processing device, and a vehicle including the sound wave system.

Background Art

[0002] Conventionally, an ultrasonic system that measures the distance to an object (obstacle) by measuring the time of flight (TOF) of ultrasonic waves generated until the reflected wave from the obstacle returns is known. Such an ultrasonic system is often mounted on a vehicle, and for example, an in-vehicle clearance sonar is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, in an ultrasonic system, it takes time until the vibration of the ultrasonic oscillator subsides even after the ultrasonic waves are transmitted by the transmission signal (see, for example, Patent Document 1). The vibration from the end of transmission of the ultrasonic waves by the transmission signal until the vibration subsides is called reverberation.

[0005] In order to be able to measure the distance to an object located far away, it is necessary to increase the power (amplitude) of the transmission. Since the power (amplitude) of the transmission does not reach the target value at the initial stage of the transmission, a certain number of waves are required to increase the power (amplitude) of the transmission. Also, when the power (amplitude) of the transmission is large, the reverberation time becomes long.

[0006] Therefore, as shown in Figure 1, when the power (amplitude) of the transmitted wave TW is large and the reverberation RVB is long, the reflected wave RW from a nearby object overlaps with the reverberation RVB, making it impossible to measure the distance to the nearby object.

[0007] On the other hand, in order to measure the distance to nearby objects, it is necessary to reduce the power (amplitude) of the transmitted wave and shorten the reverberation time. However, as shown in Figure 2, if the power (amplitude) of the transmitted wave TW is small, the reflected wave RW from distant objects cannot be detected, and the distance to distant objects cannot be measured. [Means for solving the problem]

[0008] The signal processing apparatus disclosed herein comprises: a transmit signal generation unit configured to generate a transmit signal for transmitting sound waves; a receive signal output unit configured to output a receive signal based on the reception of sound waves; and a reflected wave detection unit configured to detect reflected waves of the transmit wave that may be included in the reception based on the received signal, wherein the transmit signal includes a first signal having a first predetermined number of waves and a second signal generated after the first signal and having a second predetermined number of waves less than the first predetermined number.

[0009] The sound wave system disclosed herein comprises a signal processing device having the above configuration and a sound wave transceiver configured to be directly or indirectly connected to the signal processing device.

[0010] The vehicles disclosed herein are configured to include the acoustic system described above. [Effects of the Invention]

[0011] According to the signal processing device, sound wave system, and vehicle disclosed herein, the distance to an object can be measured whether the object is located nearby or far away. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a time chart showing transmission, reverberation, and reception when the transmission power is high. [Figure 2] Figure 2 is a time chart showing transmission, reverberation, and reception when the transmission power is low. [Figure 3] Figure 3 is a schematic diagram showing a vehicle equipped with an ultrasonic system according to the embodiment and an object. [Figure 4] Figure 4 shows the configuration of the ultrasonic system according to the embodiment. [Figure 5] Figure 5 is a time chart showing transmission, reverberation, and reception when the object is located at a distance. [Figure 6] Figure 6 is a time chart showing transmission, reverberation, and reception when the target object is located nearby. [Figure 7] Figure 7 is a diagram illustrating an example of correlation processing. [Figure 8] Figure 8 is a diagram illustrating an example of correlation processing. [Figure 9] Figure 9 is a diagram illustrating an example of the first reflected wave detection unit. [Modes for carrying out the invention]

[0013] One embodiment of the present invention will be described below with reference to the drawings. The ultrasonic system according to the embodiment described below is intended to be mounted on a vehicle as an example, and can be used for alarm functions, automatic braking functions, and automatic parking functions by measuring the distance between the vehicle and an object.

[0014] <Ultrasonic System> Figure 3 shows a vehicle 200 equipped with an ultrasonic system 100 according to an embodiment (hereinafter referred to as "ultrasonic system 100") and an object (obstacle) 300. Ultrasonic waves transmitted from the ultrasonic system 100 are reflected by the object 300 and received by the ultrasonic system 100 as reflected waves. At this time, the ultrasonic system 100 also receives environmental noise N.

[0015] The ultrasonic system 100 will be described. FIG. 4 is a diagram showing the configuration of the ultrasonic system 100.

[0016] The ultrasonic system 100 includes a signal processing device 1, a transformer Tr, and an ultrasonic transmitting and receiving device 2. The ultrasonic transmitting and receiving device 2 is externally connected to the signal processing device 1 via the transformer Tr. Note that the transformer Tr does not necessarily have to be provided.

[0017] The signal processing device 1 is a semiconductor integrated circuit device. The signal processing device 1 includes a DAC (Digital to Analog Converter) 11, a driver 12, a LNA (Low Noise Amplifier) 13, a LPF (Low Pass Filter) 14, an ADC (Analog to Digital Converter) 15, a digital processing unit 16, and external terminals T1 to T5.

[0018] The DAC 11 performs D / A conversion of the carrier signal output from the carrier signal generation unit 161 included in the digital processing unit 16 from a digital signal to an analog signal, and outputs the signal after D / A conversion to the driver 12.

[0019] The output terminals of the differential pair of the driver 12 are connected to the primary side of the transformer Tr via the external terminals T1 and T2. The ultrasonic transmitting and receiving device 2 is connected to the secondary side of the transformer Tr. The driver 12 drives the ultrasonic transmitting and receiving device 2 based on the output signal of the DAC 11.

[0020] The ultrasonic transmitting and receiving device 2 has a piezoelectric element (not shown) and transmits and receives ultrasonic waves. That is, the ultrasonic transmitting and receiving device 2 functions as both a sound source and a receiving unit.

[0021] The differential pair input terminals of LNA13 are connected to the secondary side of transformer Tr via external terminals T3 and T4. The output signal of LNA13 is supplied to ADC15 via LPF14. ADC15 performs A / D conversion of the output signal of LNA13 from an analog signal to a digital signal, and outputs the converted signal to the first reflected wave detection unit 163 and the second reflected wave detection unit 164 included in the digital processing unit 16.

[0022] LNA13, LPF14, and ADC15 are examples of a received signal output unit configured to output a received signal based on the reception of ultrasonic waves.

[0023] The digital processing unit 16 includes a transmission signal generation unit 161, a counter 162, a first reflected wave detection unit 163, a second reflected wave detection unit 164, a first TOF measurement unit 165, a second TOF measurement unit 166, and an interface 167.

[0024] The transmission signal generation unit 161 is configured to generate a transmission signal for transmitting ultrasonic waves. More specifically, when the transmission signal generation unit 161 receives a transmission command via interface 167 from an ECU (Electronic Control Unit) (not shown) mounted on the vehicle 200 (see Figure 3), it generates a transmission signal including the wavenumber and outputs the transmission signal to the DAC 11. The transmission signal includes a first signal having a first predetermined number of wavenumbers (e.g., 32 wavenumbers) and a second signal generated after the first signal and having a second predetermined number of wavenumbers less than the first predetermined number (e.g., 4 wavenumbers).

[0025] Counter 162 starts counting when the output of the first signal is started from the transmission signal generation unit 161. The count value CV of counter 162 is sent to the first reflected wave detection unit 163 and the second reflected wave detection unit 164. Counter 162 sends a count value indicating the start time of the output of the first signal as t1_start, the time when the transmission corresponding to the first signal started, to the first TOF measurement unit 165. Counter 162 sends a count value indicating the start time of the output of the second signal as t2_start, the time when the transmission corresponding to the second signal started, to the second TOF measurement unit 166.

[0026] The first reflected wave detection unit 163 detects the reflected wave corresponding to the first signal by comparing the received signal output from the ADC 15 with a detection threshold. The first reflected wave detection unit 163 detects the reflected wave corresponding to the first signal when the second reflected wave detection unit 164 does not detect a reflected wave and the received signal output from the ADC 15 is equal to or greater than the detection threshold.

[0027] The first reflected wave detection unit 163 sends a count value indicating the time when the reflected wave corresponding to the first signal was detected, as t1_detect, to the first TOF measurement unit 165.

[0028] The second reflected wave detection unit 164 detects the reflected wave corresponding to the second signal by comparing the received signal output from the ADC 15 with a detection threshold. 、 If the received signal output from ADC15 exceeds a detection threshold within a first predetermined time elapsed from the time t2_start when the transmission corresponding to the second signal began, and the time during which the received signal output from ADC15 remains above the detection threshold is less than the second predetermined time, then the reflected wave corresponding to the second signal is detected.

[0029] The second reflected wave detection unit 164 sends a count value indicating the time when the reflected wave corresponding to the second signal was detected, as t2_detect, to the second TOF measurement unit 166.

[0030] The first TOF measurement unit 165 calculates the difference between time t1_start and time t1_detect to measure the TOF when the object 300 is located far away. The second TOF measurement unit 166 calculates the difference between time t2_start and time t2_detect to measure the TOF when the object 300 is located close by. As a result, the ultrasonic system 100 can measure the distance to the object 300 whether the object 300 is located close or far away.

[0031] As described above, the first reflected wave detection unit 163 detects a reflected wave corresponding to the first signal when the second reflected wave detection unit 164 does not detect a reflected wave and the received signal output from the ADC 15 exceeds the detection threshold. Therefore, the measurement unit, composed of the first TOF measurement unit 165 and the second TOF measurement unit 166, calculates the TOF by calculating the difference between time t2_start and time t2_detect when the second reflected wave detection unit 164 can detect a reflected wave corresponding to the second signal, and calculates the TOF by calculating the difference between time t1_start and time t1_detect when the second reflected wave detection unit 164 cannot detect the reflected wave corresponding to the second signal and the first reflected wave detection unit 163 can detect a reflected wave corresponding to the first signal. This allows for efficient and accurate measurement of the TOF.

[0032] Interface 167, for example, conforms to LIN (Local Interconnect Network) and communicates with an unshown ECU mounted on vehicle 200 (see Figure 3) via external terminal T5.

[0033] The distance to the object 300 can be determined by the speed of the TOF and the ultrasonic waves transmitted from the ultrasonic transceiver 2. The measurement results from the first TOF measurement unit 165 and the second TOF measurement unit 166 are sent via interface 167 to an ECU (not shown) mounted on the vehicle 200 (see Figure 3).

[0034] Figure 5 is a time chart showing transmission, reverberation, and reception when the object is located far away. Figure 6 shows the time chart showing when the object is located far away. near This is a time chart showing transmission, reverberation, and reception when located in a specific position.

[0035] In Figures 5 and 6, transmitter TW1 is the transmitter corresponding to the first signal. In Figures 5 and 6, reverberation RVB1 is the reverberation that occurs immediately after transmitter TW1. In Figures 5 and 6, transmitter TW2 is the transmitter corresponding to the second signal. In Figures 5 and 6, reverberation RVB2 is the reverberation that occurs immediately after transmitter TW2. In Figures 5 and 6, receiver RW1 is the receiver corresponding to the first signal. In Figures 5 and 6, receiver RW2 is the receiver corresponding to the second signal.

[0036] As shown in Figures 5 and 6, it is desirable that the maximum amplitude of the transmitting wave TW1 be greater than the maximum amplitude of the transmitting wave TW2. This ensures sufficient power for the transmitting wave TW1, allowing the ultrasonic system 100 to more reliably measure the distance to the object 300 whether it is located close or far away.

[0037] Furthermore, it is desirable that the transmitting signal generation unit 161 be configured to generate the second signal after the reverberation RVB1 following the first signal has finished. The end of the reverberation RVB1 may be actually confirmed by the transmitting signal generation unit 161 using the output of the LNA 13, or the transmitting signal generation unit 161 may store in advance the time at which it can be estimated that the reverberation RVB1 has definitely finished through experiments, simulations, etc. By generating the second signal after the reverberation RVB1 following the first signal has finished, the ultrasonic system 100 can more reliably measure the distance to the object 300 whether the object 300 is located close or far away.

[0038] <Other> Furthermore, the configuration of the present invention can be modified in various ways without departing from the spirit of the invention, in addition to the embodiments described above. The embodiments described above should be considered to be illustrative and not restrictive in all respects, and the technical scope of the present invention is indicated by the claims, not by the description of the embodiments described above, and should be understood to include all modifications that fall within the meaning and scope equivalent to the claims.

[0039] In the embodiment described above, the reflected wave was detected by comparing the reflected wave with a detection threshold, but the reflected wave may also be detected by correlation processing.

[0040] Here, the overview of the correlation process will be explained using Figures 7 and 8. In Figure 7, reference data Dref is prepared in advance. Reference data Dref is the waveform data of the reflected wave that is expected to be received, and it is waveform data with the same frequency as the frequency of the transmitted sound wave. The frequency of the received reflected wave Rs1 shown in Figure 7 is the same as the transmission frequency. Therefore, the correlation result C1 obtained by the correlation process, which multiplies the reference data Dref and the reflected wave Rs1, always has a positive correlation value, as shown in Figure 7. As a result, the convolution integral value obtained by integrating the correlation result C1 over time becomes large, and the reflected wave is emphasized.

[0041] On the other hand, the frequency of the received environmental noise N (see Figure 3), shown in Figure 8, is different from the transmission frequency. That is, the frequency of environmental noise N is different from the frequency of the reference data Dref. Consequently, as shown in Figure 8, there is a period in the correlation result C2 where the correlation value is negative, and the convolution integral value becomes smaller compared to Figure 7. In this way, it is possible to distinguish between reflected waves based on transmission and environmental noise.

[0042] When the first reflected wave detection unit 163 of the ultrasonic system 100 is modified to detect the reflected wave corresponding to the first signal by correlation processing, the first reflected wave detection unit 163 will have the configuration shown in Figure 9, for example.

[0043] The first reflected wave detection unit 163 in the example shown in Figure 9 includes a reference data storage unit 163A, a correlation processing unit 163B, a correlation value summing unit 163C, and a threshold determination unit 163D. The reference data storage unit 163A is configured to store reference data corresponding to the first signal. For example, a register can be used for the reference data storage unit 163A.

[0044] The correlation processing unit 163B performs correlation processing at a predetermined period based on the received signal output from the ADC 15 and the reference data stored in the reference data storage unit 163A.

[0045] The correlation value summing unit 163C outputs a correlation convolution integral value by calculating the sum of the correlation processing results from the correlation processing unit 163B. Note that the output correlation convolution integral value may be calculated by truncating negative values, where negative values ​​are treated as zero.

[0046] The threshold determination unit 163D compares the correlated convolution integral value with a predetermined threshold. When the correlated convolution integral value becomes greater than the predetermined threshold, the threshold determination unit 163D detects the reflected wave corresponding to the first signal.

[0047] An example of the second reflected wave detection unit 164 is the same as an example of the first reflected wave detection unit 163. However, in the second reflected wave detection unit 164, reference data corresponding to the second signal is used instead of reference data corresponding to the first signal.

[0048] Furthermore, by setting the frequencies of the first signal and the second signal to be different from each other, it is possible to suppress erroneous measurement of TOF in the first TOF measurement unit 165 and the second TOF measurement unit 166, respectively.

[0049] In the above embodiment, an ultrasonic system 100 that transmits ultrasonic waves (sound waves with high frequencies exceeding audible sound) was described, but the present invention can also be applied to sound wave systems that transmit sound waves other than ultrasonic waves.

[0050] The signal processing device (1) described above comprises a transmission signal generation unit (161) configured to generate a transmission signal for transmitting sound waves, a reception signal output unit (13, 14, 15) configured to output a reception signal based on the reception of sound waves, and a reflected wave detection unit (163, 164) configured to detect reflected waves of the transmission that may be included in the reception based on the reception signal, wherein the transmission signal has a configuration (first configuration) that includes a first signal having a first predetermined number of waves and a second signal that is generated after the first signal and has a second predetermined number of waves that is less than the first predetermined number.

[0051] The signal processing device, which is the first configuration described above, is capable of measuring the distance to an object whether the object is located close or far away. The measurement of the distance to the object may be performed outside the signal processing device or inside the signal processing device.

[0052] In the signal processing device having the first configuration described above, the maximum amplitude of the transmission wave corresponding to the first signal may be greater than the maximum amplitude of the transmission wave corresponding to the second signal (second configuration).

[0053] The signal processing device, which is the second configuration described above, makes it possible to more reliably measure the distance to an object whether the object is located close by or far away.

[0054] In the signal processing apparatus having the first or second configuration described above, the transmitting signal generation unit may be configured to generate the second signal after the reverberation following the first signal has ended (third configuration).

[0055] The signal processing device, which is the third configuration described above, makes it possible to more reliably measure the distance to an object whether the object is located close by or far away.

[0056] In a signal processing device having any of the first to third configurations described above, the device may also be configured to include a measuring unit, wherein the measuring unit measures the time from the transmission of the wave corresponding to the second signal to the detection of the reflected wave corresponding to the second signal when the reflected wave corresponding to the second signal can be detected by the reflected wave detection unit, and measures the time from the transmission of the wave corresponding to the first signal to the detection of the reflected wave corresponding to the first signal when the reflected wave corresponding to the second signal cannot be detected by the reflected wave detection unit and the reflected wave corresponding to the first signal can be detected by the reflected wave detection unit (fourth configuration).

[0057] The signal processing device, which is the fourth component described above, can efficiently and accurately measure the TOF (Time of Flight).

[0058] In a signal processing device having any of the first to fourth configurations described above, the reflected wave detection unit may be configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the correlation between the received signal and the reference data (fifth configuration).

[0059] The signal processing device, which is the fifth configuration described above, can improve robustness against environmental noise.

[0060] In the signal processing device having the fifth configuration described above, the frequencies of the first signal and the second signal may be different from each other (sixth configuration).

[0061] The signal processing device, which is the sixth configuration described above, can suppress erroneous measurement of TOF.

[0062] The sound wave system (100) described above has a configuration (the seventh configuration) comprising a signal processing device having one of the first to sixth configurations described above, and a sound wave transmitting and receiving device (2) configured to be directly or indirectly connected to the signal processing device.

[0063] The seventh configuration described above, the sound wave system, can measure the distance to an object whether the object is located close by or far away.

[0064] The vehicle (200) described above is configured to include the sound wave system of the seventh configuration described above (the eighth configuration).

[0065] In the eighth configuration of the vehicle described above, the distance to the object measured by the sound wave system can be used whether the object is located nearby or far away. [Explanation of Symbols]

[0066] 1. Signal Processing Device 2. Ultrasonic Transceiver 11 DAC 12 drivers 13 LNA 14 LPF 15 ADC 16 Digital Processing Unit 161 Wave transmission signal generation unit 162 counters 163 First Reflected Wave Detection Unit 163A Reference data storage unit 163B Correlation Processing Unit 163C Correlation Value Sum Unit 163D Threshold determination unit 164 Second Reflected Wave Detection Unit 165 First TOF Measurement Unit 166 Second TOF Measurement Unit 167 Interfaces 100 Ultrasonic system according to the embodiment 200 vehicles 300 Objects (obstacles) T1~T5 External terminals Tr transformer

Claims

1. A transmission signal generation unit configured to generate a transmission signal for transmitting sound waves, A receiving signal output unit configured to output a receiving signal based on the reception of sound waves, A reflected wave detection unit is configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the received wave signal, Equipped with, The transmitted signal includes a first signal having a first predetermined number of waves and a second signal generated after the first signal and having a second predetermined number of waves that is less than the first predetermined number. A signal processing device wherein the maximum amplitude of the transmission wave corresponding to the first signal is greater than the maximum amplitude of the transmission wave corresponding to the second signal.

2. A transmission signal generation unit configured to generate a transmission signal for transmitting sound waves, A receiving signal output unit configured to output a receiving signal based on the reception of sound waves, A reflected wave detection unit is configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the received wave signal, Equipped with, The transmitted signal includes a first signal having a first predetermined number of waves and a second signal generated after the first signal and having a second predetermined number of waves that is less than the first predetermined number. The signal processing device is configured such that the transmitted signal generation unit generates the second signal after the reverberation following the first signal has ended.

3. A transmission signal generation unit configured to generate a transmission signal for transmitting sound waves, A receiving signal output unit configured to output a receiving signal based on the reception of sound waves, A reflected wave detection unit is configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the received wave signal, Measurement unit and Equipped with, The transmitted signal includes a first signal having a first predetermined number of waves and a second signal generated after the first signal and having a second predetermined number of waves that is less than the first predetermined number. The aforementioned measuring unit is When the reflected wave detection unit can detect the reflected wave corresponding to the second signal, the time from the transmission of the wave corresponding to the second signal to the detection of the reflected wave corresponding to the second signal is measured. A signal processing device configured to measure the time from the transmission of the wave corresponding to the first signal to the detection of the reflected wave corresponding to the first signal when the reflected wave corresponding to the second signal cannot be detected by the reflected wave detection unit and the reflected wave corresponding to the first signal can be detected by the reflected wave detection unit.

4. A transmission signal generation unit configured to generate a transmission signal for transmitting sound waves, A receiving signal output unit configured to output a receiving signal based on the reception of sound waves, A reflected wave detection unit is configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the received wave signal, Equipped with, The transmitted signal includes a first signal having a first predetermined number of waves and a second signal generated after the first signal and having a second predetermined number of waves that is less than the first predetermined number. The reflected wave detection unit is configured to detect the reflected wave of the transmitted wave that may be included in the received wave based on the correlation between the received signal and the reference data. A signal processing device in which the frequencies of the first signal and the frequencies of the second signal are different from each other.

5. A signal processing apparatus according to any one of claims 1 to 4, A sound wave system comprising a sound wave transceiver configured to be directly or indirectly connected to the signal processing device.

6. A vehicle comprising the sound wave system described in claim 5.

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