Object detection device

Abstract

Object detection device (200, 201, 202, 203, 204) with: a transmitting section (411) configured to transmit a wave based on at least two frequencies (f1, f2) set within a range of a predetermined frequency band (FB), a receiving section (421) configured to receive a receiving wave based on the transmitted wave returned in response to a reflection from an object (O), an estimation section (425) configured to estimate the magnitude of a frequency change due to a Doppler shift between the transmitting wave and the receiving wave based on the result of a frequency analysis on the receiving wave and transmitting frequency information that specifies a relationship between the at least two frequencies of the transmitting wave, a correction section (426) configured to correct the received wave to obtain frequency consistency with the transmitted wave based on an estimation result of the estimation section (425), and a detection section (430) which is configured to detect information relating to the object (O) based on a relationship between the transmitted wave and the corrected received wave which has been corrected by the correction section (426).

Description

Technical field

[0001] This disclosure generally relates to an object detection device. State of the art

[0002] DE 10 2011 109 915 A1 discloses a method for verifying the origin of a received signal from an ultrasonic sensor of a motor vehicle, wherein a transmitted signal of the ultrasonic sensor is modulated and a predetermined codeword is imprinted on the transmitted signal by this modulation, the received signal is compared with a reference signal, and the origin of the received signal is determined based on the result of the comparison. Before comparing the received signal with the reference signal, a frequency shift of the received signal relative to the transmitted signal is determined, and the received signal is compared with the transmitted signal, shifted in frequency by the determined frequency shift, as the reference signal.

[0003] In a known technique, a correlation value is obtained (calculated) between a transmitted wave and a received wave, which acts as the transmitted wave that has been reflected by an object and then returned; based on the correlation value, a determination is made as to whether the degree of similarity between the transmitted wave and the received wave is at a level equal to or greater than a predetermined level; and a distance to the object, which is a piece of information relating to the object, is determined, for example, by a time-of-flight (TOF) method, based on the detection result (for example, JP 2005 - 249 770 A, which is also referred to as patent reference 1).

[0004] In the known technique described above, a frequency shift (a frequency transition) can occur due to a Doppler shift between the transmitted and received waves. In such a case, if the magnitude of the frequency shift is not appropriately accounted for, the received wave, which acts as the transmitted wave that has been reflected by and then returned to a target object, cannot be correctly detected.

[0005] Therefore, it is an object of the present disclosure to specify an object detection device that accurately detects a received wave acting as a transmitted wave, which is reflected and then returned by an object that is a detection target, and detects an exact distance to the object itself in a case where a frequency change occurs due to a Doppler shift. Summary

[0006] This problem is solved by an object detection device as specified in claim 1.

[0007] According to one embodiment of the disclosure, an object detection device comprises: a transmitting section configured to transmit a transmitting wave based on at least two frequencies set within a range of a predetermined frequency band; a receiving section configured to receive a receiving wave based on the transmitting wave, which is reflected back in response to a reflection from an object; an estimating section configured to estimate the magnitude of a frequency change due to a Doppler shift between the transmitting wave and the receiving wave based on the result of a frequency analysis of the receiving wave and transmitting frequency information specifying a relationship between the at least two frequencies of the transmitting wave; and a correction section configured to correct the receiving wave.to obtain consistency of frequencies with the transmitting wave based on an estimation result of the estimation section, and a detection section configured to detect information relating to the object based on a relationship between the transmitting wave and the corrected received wave, which has been corrected by the correction section.

[0008] According to the configuration described above, even in a case where the frequency change is caused by the Doppler shift, the received wave is corrected in such a way that any influence from the frequency change is eliminated, and thus the received wave, which acts as the transmitted wave reflected by the target object and then returned, is accurately detected, and thus the distance to the object is accurately detected as the information relating to the object.

[0009] According to a further embodiment of the disclosure, the transmitting section, as the transmitting wave, sends a plurality of temporarily continuous wave motions, which exhibit a combination of at least two wave motions, the signal levels of which reach peak values ​​at the at least two frequencies, and the estimating section, based on the result of the frequency analysis and the transmitting frequency information, identifies a correspondence relationship between one or more frequencies at which a signal level of the receiving wave reaches a peak value and the at least two frequencies of the transmitting wave, and estimates the magnitude of the frequency change based on a difference between the frequencies that correspond to each other.

[0010] According to the configuration described above, the magnitude of the frequency change can be easily determined according to the correspondence relationship between the frequencies of the receiving wave and the frequencies of the transmitting wave, whereby the correspondence relationship is identified based on the result of the frequency analysis and the transmitting frequency information.

[0011] According to a further embodiment of this disclosure, in a case where a number of the one frequency or several frequencies of the receiving wave and a number of the at least two frequencies of the transmitting wave are equal to each other, the estimation section identifies the correspondence relationship between the one frequency or several frequencies of the receiving wave and the at least two frequencies of the transmitting wave on the basis of a correspondence between the one frequency or several frequencies of the receiving wave and the at least two frequencies of the transmitting wave with each other, or on the basis of a correspondence between a magnitude relationship between the one frequency or several frequencies of the receiving wave and a magnitude relationship between the at least two frequencies of the transmitting wave with each other.

[0012] According to the configuration described above, in a case where the magnitude of the frequency change caused by the Doppler shift is so small that the number of one or more frequencies of the receiving wave and the number of at least two frequencies of the transmitting wave coincide, the correspondence relationship of the frequencies can be easily identified by considering the correspondence of the frequencies of the receiving wave and the transmitting wave with each other or the correspondence of the magnitude relationships of the frequencies with each other.

[0013] According to a further embodiment of this disclosure, in a case where a number of the one frequency or several frequencies of the receiving wave and a number of the at least two frequencies of the transmitting wave differ from each other, the estimation section identifies the correspondence relationship between the one frequency or several frequencies of the receiving wave and the at least two frequencies of the transmitting wave on the basis of an empty band that exists on a low-range side and / or a high-range side with respect to the one frequency or several frequencies of the receiving wave within the range of the frequency band mentioned above.

[0014] According to the configuration described above, even in a case where the magnitude of the frequency change caused by the Doppler shift is so large that the number of one or more frequencies of the received wave and the number of at least two frequencies of the transmitted wave do not match, the correspondence relationship between the frequencies can be easily identified by taking the blank band into account.

[0015] According to a further embodiment of this disclosure, the at least two wave movements are each linked with information that differs from each other in such a way that the multitude of wave movements are coded to exhibit predetermined identification information, with the transmitting section, as the transmitting wave, transmitting the coded multitude of wave movements.

[0016] According to the configuration described above, it can easily be identified, using the identification information, whether the received wave corresponds to the transmitted wave that was reflected and then returned by the object acting as the target of the detection.

[0017] According to a further embodiment of this disclosure, the object detection device further comprises a correlation processing section configured to obtain a correlation value corresponding to a degree of similarity between the transmitted wave and the corrected received wave, wherein the detection section, based on a comparison result of the correlation value and a threshold value, captures the information relating to the object in a case where the degree of similarity between the transmitted wave and the corrected received wave is determined to be at a level equal to or greater than a predetermined level.

[0018] According to the configuration described above, the received wave can be correctly identified, using the correlation value, as the transmitted wave that has been reflected by and returned from the target object. Thus, the distance to the object, which serves as the information relating to the object, can be accurately determined.

[0019] According to a further embodiment of this disclosure, the detection section captures as the information relating to the object a distance to the object based on a difference between a time at which the transmitting wave was sent and a time at which the receiving wave, which serves as a basis for the corrected receiving wave, the degree of similarity of which with respect to the transmitting wave is determined to be at the level which is equal to or greater than the predetermined level, was received.

[0020] According to the configuration described above, the distance to the object can be easily determined.

[0021] According to a further embodiment of this disclosure, at least two frequencies of the transmitting wave are each set within areas of at least two bands, which are formed by virtually subdividing the predetermined frequency band, and the at least two bands do not overlap.

[0022] According to the configuration described above, the at least two frequencies of the transmitting wave can be easily set by the band division.

[0023] According to a further embodiment of this disclosure, the transmitting section and the receiving section are integrally configured together as a transmitting and receiving section with a single vibration generating device configured to transmit and receive a sound wave, wherein the predetermined frequency is set according to specifications of the vibration device.

[0024] According to the configuration described above, the configuration for sending and receiving the transmit and receive waves can be simplified, and the predetermined frequency band FB can be easily set. Brief description of the drawings

[0025] The foregoing and additional features and characteristics of this disclosure will become clearer with reference to the following detailed description and the accompanying drawings. These show: Fig. 1 A schematic representation, seen from above, illustrating the exterior of a vehicle equipped with an object detection system with a distance detection device according to an embodiment disclosed herein, Fig. 2 a schematic block diagram illustrating a schematic hardware configuration of an ECU (electronic control unit) and the distance sensing device according to the exemplary embodiment, Fig. 3 a schematic representation to illustrate an outline of a technique used by the distance detection device according to the embodiment to detect a distance to the object, Fig. 4 a schematic block diagram illustrating a detailed configuration of the distance sensing device according to the exemplary embodiment, Fig. 5 a schematic representation illustrating an example of a frequency of a transmitting wave according to the embodiment, Fig. 6 a schematic representation illustrating an example of a code assigned to the transmitting wave according to the embodiment, Fig. 7 a schematic representation illustrating an example of a frequency of a received wave according to the embodiment, Fig. 8 a schematic representation illustrating a further example of the frequency of the received wave according to the embodiment, and Fig. 9 a schematic flowchart indicating a processing sequence carried out by the distance detection device according to the embodiment for acquiring information relating to the object. Detailed description

[0026] An embodiment of the present disclosure is described with reference to the drawings. The configurations according to the embodiment and the variations described below, as well as the operation and results (advantages and effects) obtained by the configurations, are examples, and the present disclosure is not limited thereto.

[0027] Fig. Figure 1 shows a schematic example view, seen from above, illustrating the exterior of a vehicle 1 equipped with an object detection system comprising a distance detection device according to the exemplary embodiment. As described later, the object detection system according to the exemplary embodiment is a vehicle-integrated sensor system that transmits and receives ultrasonic waves and, for example, obtains a time difference between transmission and reception, thereby acquiring information relating to an object that includes a human being or person present in the environment (for example, a person in the vehicle). Fig. 2. specified obstacle O, which will be described later).

[0028] As it is in Fig. As illustrated in Figure 1, the object detection system comprises an ECU (electronic control unit) 100 located inside the vehicle 1 and distance sensing devices 201, 202, 203, and 204 located on the exterior of the vehicle 1. The vehicle 1 is equipped with four wheels, including a pair of front wheels 3F and a pair of rear wheels 3R. The distance sensing devices 201, 202, 203, and 204 are examples of an “object detection device.”

[0029] As an example, in the Fig. Figure 1 illustrates the distance sensing devices 201 to 204 being provided, for example, on a rear bumper at a rear end of the vehicle body 2, which acts as the exterior of the vehicle 1, so that they are arranged in different positions from each other.

[0030] According to the exemplary embodiment, the hardware configurations and functions of the respective distance sensing devices 201, 202, 203, and 204 are identical to each other. Therefore, for the sake of simplicity, the distance sensing devices 201, 202, 203, and 204 are also referred to collectively as the distance sensing device 200 below.

[0031] According to the exemplary embodiment, the position at which the distance detection device 200 is arranged is not based on the in Fig. The illustrated example is limited. For example, the distance sensing device 200 can be provided on a front bumper at a front end of the vehicle body 2, on one or more side surfaces of the vehicle body 2, or on two or more of the rear bumper, the front bumper, and the side surfaces. According to the exemplary embodiment, the number of distance sensing devices 200 is not limited to that shown in the illustration. Fig. One illustrated example is limited.

[0032] Fig. Figure 2 illustrates a schematic example block diagram that demonstrates a hardware configuration of the ECU 100 and the distance sensing device 200 according to the exemplary embodiment.

[0033] As it is in Fig. As illustrated in Figure 2, the ECU 100 has a hardware configuration similar to that of a typical computer. More precisely, the ECU 100 has an input / output device 110, a storage device 120, and a processor 130.

[0034] The input and output device 110 is an interface for sending and receiving information between the ECU 100 and external devices (such as the distance detection device 200, as shown in the example of...). Fig. 1).

[0035] For example, the storage device 120 has a main memory with a ROM (read-only memory) and / or a RAM (random access memory) and / or an auxiliary memory with an HDD (hard disk drive) and / or an SSD (solid-state drive).

[0036] Processor 130 controls various processing operations performed in ECU 100. For example, Processor 130 includes an arithmetic unit with a CPU (central processing unit). Processor 130 performs various functions, including autonomous or automatic parking, by reading a computer program stored in memory device 120 and executing that program.

[0037] As it is in Fig. As illustrated in Figure 2, the distance detection device 200 has a transmit and receive section 210 and a control section 220.

[0038] The transmitting and receiving section 210 has a vibration generating device 211, which, for example, has a piezoelectric element, and performs the transmitting and receiving of the ultrasonic waves using the vibration generating device 211.

[0039] More precisely, the transmitting and receiving section 210 sends an ultrasonic wave as a transmitting wave, which is generated in response to vibrations of the vibration-generating device 211. The transmitting and receiving section 210 then receives vibrations from the vibration-generating device 211 as a receiving wave, the vibrations being caused in such a way that the ultrasonic wave transmitted as the transmitting wave is reflected by an external object, and the reflected wave returns. In the example of Fig. 2 is an obstacle O arranged on a road surface RS, illustrated as the object that reflects the ultrasonic wave from the transmitting and receiving section 210.

[0040] According to the configuration of the in Fig. In the illustrated example 2, both the transmission of the transmitting wave and the reception of the receiving wave are realized or carried out by the individual transmitting and receiving section 210, which is equipped with the individual vibration generating device 211. However, the technology according to the exemplary embodiment is also applicable to a configuration in which a transmitting side configuration and a receiving side configuration are separate from each other, including a configuration in which, for example, a first vibration generating device for transmitting the transmitting wave and a second vibration generating device for receiving the receiving wave are provided separately from each other.

[0041] The control section 220 has a hardware configuration similar to that of a typical computer. More precisely, the control section 210 includes an input / output device 221, a storage device 222, and a processor 223.

[0042] The input and output device 221 is an interface for enabling the sending and receiving of information between the control section 220 and external devices (the ECU 100 and the transmit and receive section 210 in the example of Fig. 1).

[0043] The storage device 222 has a main memory with a ROM and / or a RAM and / or an auxiliary memory with an HDD and / or an SSD, for example.

[0044] The processor 223 controls various processing operations that are performed in the control section 220. For example, the processor 223 includes an arithmetic device with a CPU. For instance, the processor 223 performs various functions by reading a computer program stored in the memory device 222 and subsequently executing the computer program.

[0045] The distance measuring device 200 according to the exemplary embodiment detects a distance from the distance measuring device 200 to the object using a technique known as a TOF (time-of-flight) method. As will be described in detail later, the TOF method is a technique in which a distance to an object is calculated taking into account the difference between a time at which a transmitted wave was sent (more precisely, a time at which the transmission of the transmitted wave started) and a time at which the received wave was received (more precisely, a time at which the reception of the received wave started).

[0046] Fig. Figure 3 shows a schematic example view to illustrate an overview of a technique used by the distance detection device 200 to detect the distance to the object according to the exemplary embodiment. In more detail, Figure 3 shows... Fig. 3 A view that schematically illustrates in graphical form a temporal change in a signal level (for example, an amplitude) of an ultrasonic wave that is transmitted and received by the distance detection device 200 according to the exemplary embodiment. In the Fig. In the graphs illustrated in 3, the horizontal axis corresponds to time and the vertical axis corresponds to the signal level of the signal that is sent and received by the distance detection device 200 via the transmit and receive section 210 (the vibration generating device 211).

[0047] In the Fig. In the graph 3, a solid line L11 provides an example of the signal level of the signal that the distance detection device 200 sends and receives; that is, an envelope that indicates the temporal change (the change over time) of a degree of vibration (oscillation) of the vibration generating device 211. From the solid line L11, it can be seen that the vibration generating device 211 is activated and oscillates from time t0 for a time Ta, thus completing the transmission of the wave at time t1. Thereafter, due to inertia, the vibration generating device 211 continues to oscillate for a time Tb until time t2 is reached, during which time the vibration is attenuated or damped. Accordingly, in the graph shown in the diagram, the vibration level is represented by the solid line L11. Fig. 3 illustrated graphs the time Tb of a so-called reverberation time.

[0048] The solid line L11 reaches a peak value at time t14, when a time Tp has elapsed since the start of the transmission of the transmit wave at time t0. At the peak value, the degree of vibration of the vibration-generating device 211 exceeds (or is equal to or greater than) a predetermined threshold Th1, which is indicated by an alternating long and short dashed line L21. The predetermined threshold Th1 is a value preset to identify or distinguish whether the vibration of the vibration-generating device 211 results from receiving the received wave corresponding to the transmitted wave transmitted by a detection target object (the object that is a target of detection, including the obstacle O, for example, in Fig. 2 is illustrated) has been reflected and then returned, or the vibration of the vibration-generating device 211 results from the reception of the receiving wave corresponding to the transmitted wave, which is reflected by an object other than the detection target object (for example, the one in Fig. 2 illustrated road surface RS) has been reflected and then returned.

[0049] Fig. Figure 3 illustrates an example where the predetermined threshold Th1 is set as a constant value that does not vary or change over time; however, according to the embodiment, the predetermined threshold Th1 can be set to a value that changes over time.

[0050] It can be considered that the vibration whose peak value exceeds (or is equal to or greater than) the predetermined threshold Th1 results from the reception of the received wave corresponding to the transmitted wave, which was reflected by the object being detected and then reflected back. Conversely, it can be considered that the vibration whose peak value is equal to or less than (or lower than) the predetermined threshold Th1 results from the reception of a received wave corresponding to the transmitted wave, which was reflected by an object other than the target being detected and then reflected back.

[0051] Consequently, it can be seen from the solid line L11 that the vibration of the vibration generating device 211 at time t4 is caused by the reception of the received wave, which corresponds to the transmitted wave that has been reflected and returned by the detection target object.

[0052] According to the solid line L11, the vibration of the vibration-generating device 211 is attenuated at time t4 and thereafter. Thus, time t4 corresponds to the point in time at which the reception of the received wave, which acts as the transmitted wave that was reflected by the detection target and returned, is completed; in other words, time t4 corresponds to the point in time at which the transmitted wave, which was last sent at time t1, returns as the received wave.

[0053] According to the solid line L11, time t3, which acts as the starting point of the peak value of time t4, corresponds to the point in time at which the reception of the received wave, corresponding to the transmitted wave that was reflected by the target object and then returned, began. In other words, time t3 corresponds to the point in time at which the transmitted wave, first sent at time t0, returns as the received wave. Consequently, according to the solid line L11, the time ΔT from time t3 to time t4 is equal to the time Ta, which acts as the transmission time of the transmitted wave.

[0054] In light of the above description, to maintain the distance to the object being detected, the TOF method must obtain a time Tf from time t0, when the transmission of the transmitting wave was initiated, until time t3, when the reception of the receiving wave was initiated. The time Tf can be obtained by subtracting the time ΔT, which is equal to the time Ta, corresponding to the transmission time of the transmitting wave, from the time Tp, which is the difference between time t0 and time t4, when the signal level of the receiving wave reaches its peak value exceeding the threshold Th1.

[0055] The time t0, at which the transmission of the transmitted wave is initiated, can easily be identified as the time at which the distance detection device 200 begins operation. The time Ta, corresponding to the transmission time of the transmitted wave, is predetermined, for example, by presetting. Accordingly, to maintain the distance to the target object using the TOF method, it is important to identify the time t4, at which the signal level of the received wave reaches the peak value exceeding the threshold Th1. Accurate detection of the received wave is crucial for identifying the time t4, where the received wave is the transmitted wave reflected by the target object and then returned.

[0056] In a case where the distance detection device 200 and / or the target object is moving, a frequency shift due to a Doppler shift between the transmitted and received waves may occur. In such a case, the received wave, which acts as the transmitted wave that has been reflected by the target object and then returned, may not be accurately detected.

[0057] According to the embodiment, by configuring the distance detection device 200 as described below, even in a case where the frequency change is caused by the Doppler shift, the received wave, which acts as the transmitted wave that has been reflected by the detection target object and then returned, is accurately detected, and the distance to the object is accurately detected.

[0058] Fig. Figure 4 shows a schematic example block diagram illustrating a detailed configuration of the distance sensing device 200 according to the exemplary embodiment. In the Fig. In the four illustrated examples, the configuration of the sending side and the configuration of the receiving side are separate; however, the configuration shown in Fig. Figure 4 illustrates the method to facilitate description. As described above, according to the exemplary embodiment, both the transmission of the transmitting wave and the reception of the receiving wave are realized by the (single) transmitting and receiving section 210 with the (single) vibration generating device 211. However, as described above, the technique according to the exemplary embodiment is also applicable to the configuration in which the transmitting side and the receiving side configurations are separate.

[0059] As it is in Fig. As illustrated in Figure 4, the distance detection device 200 has a wave transmitter 411, a code generation section 412, a carrier wave output section 413, a multiplier 414, and an amplifier circuit 415 as the transmitting configuration. The wave transmitter 411 is an example of a "transmitting section".

[0060] The distance sensing device 200 comprises a wave receiver 421, an amplifier circuit 422, a filter processing section 423, a frequency analysis section 424, an estimation section 425, a correction section 426, a correlation processing section 427, an envelope processing section 428, a threshold processing section 429, and a sensing section 430 as the receive-side configuration. The wave receiver 421 is an example of a "receive section".

[0061] According to the exemplary embodiment, at least a part of the in Fig. The configuration illustrated in Figure 4 can be implemented solely by hardware (an analog circuit), and the remaining part can be implemented as a result of cooperation between hardware and software, more precisely, as a result of the processor 223 of the distance sensing device 200 reading a computer program from the storage device 222 and executing the computer program. According to the exemplary embodiment, each of the configurations shown in Figure 4 can be implemented as follows: Fig. The 4 illustrated configurations operate under the control of the control section 220 of the distance detection device 200 or operate under the control of the ECU 100 outside.

[0062] First, the configuration of the sending side is briefly described.

[0063] The wave transmitter 411 is configured from the vibration generating device 211 and sends the transmitting wave according to a transmit signal that is output from the amplifier circuit 415 (that is, an amplified transmit signal) via the vibration generating device 211.

[0064] According to the exemplary embodiment of the wave transmitter 411, the transmitting wave is sent using two frequencies in two bands, which are shaped by virtually or imaginarily dividing a predetermined frequency band, as described in Fig. 5 is illustrated.

[0065] Fig. Figure 5 shows a schematic example diagram illustrating an example of a transmitting wave frequency according to the embodiment. In the example of Fig. 5. The horizontal axis indicates a frequency and the vertical axis indicates a signal level (for example, PSD, i.e., power spectral density).

[0066] As it is in Fig. As illustrated in Figure 5, according to the exemplary embodiment, the transmitted wave is sent using two bands B1 and B2, which are shaped by virtually dividing a predetermined frequency band FB into two in such a way that the two bands B1 and B2 do not overlap. According to the exemplary embodiment, the transmitted wave is sent as temporarily continuous multiple wave motions, which exhibit a combination of a wave motion with a center frequency f1 of band FB1 and a wave motion with a center frequency f2 of band B2, as described in detail below.

[0067] In the Fig. In the illustrated example 5, the center frequency f1 of band B1 corresponds to the result obtained by subtracting a predetermined frequency Δf from a center frequency fc of the predetermined frequency band FB. The center frequency f2 of band B2 corresponds to the result obtained by adding the predetermined frequency Δf to the center frequency fc of the predetermined frequency band FB.

[0068] In the Fig. In the illustrated example 5, the predetermined frequency band FB is set, for instance, according to the specifications of the vibration generating device 211. Accordingly, a lower cutoff frequency fa and an upper cutoff frequency FB of the predetermined frequency band FB correspond, respectively, to the maximum frequency and the minimum frequency that the vibration generating device 211 can transmit, that is, the maximum frequency and the minimum frequency that the vibration generating device 211 is capable of transmitting.

[0069] According to the embodiment, the wave transmitter 411 encodes the transmitted wave by frequency modulation based on the frequency band division described above, using the center frequency f1 of band B1 and the center frequency f2 of band B2, and transmits the encoded transmitted wave.

[0070] For example, linked as it is through the in Fig. As illustrated in Figure 6, the wave transmitter 411 combines the wave motion (hereinafter referred to as a first wave motion W1) of the center frequency f1 of band B1 with information and associates the wave motion (hereinafter referred to as a second wave motion W2) of the center frequency f2 of band B2 with other information, wherein the information associated with the first wave motion W1 and the information associated with the second wave motion W2 are different from each other, the information each being formed from a code with a bit of 0 or 1, for example. By configuring or forming a temporary continuous combination of the first wave motion W1 and the second wave motion W2 as a group of transmit waves, the wave transmitter 411 transmits the transmit wave to which identification information with a predetermined code length has been assigned.

[0071] Fig. Figure 6 shows a schematic example diagram illustrating an example of the code assigned to the transmitted wave according to the embodiment. In the Fig. In the illustrated example 6, the wave transmitter 411 associates the first wave motion W1 with a code of one bit of 1 (one) and associates the second wave motion W2 with a code of one bit of 0 (zero), and transmits the transmission wave as the group of transmission waves with two first wave motions W1, W2, a second wave motion W2, and another first wave motion W1, which are combined with each other in the temporarily continuous or successive manner in the order given above. Accordingly, in the Fig. Figure 6 illustrated the transmitted wave, to which a code of a bit sequence of 1101 (known as the Barker code) has been assigned as the identification information.

[0072] According to Fig. 4. The code generation section 412 generates a signal according to the identification information described above, which is to be assigned to the transmitting wave; that is, the code generation section 412 generates a pulse signal according to the code of the bit sequence formed from the continuous sequence of bits of 1 or 0.

[0073] The carrier wave output section 413 outputs a carrier wave that acts as a signal to which the identification information is assigned. For example, the carrier wave output section 413 outputs a sine wave of a predetermined frequency as the carrier wave.

[0074] The multiplier 414 modulates the carrier wave such that the identification information is assigned by multiplying the output from the code generation section 412 and the output from the carrier wave output section 413. That is, the multiplier 414 outputs the temporary continuous combination of the first wave movement W1 and the second wave movement W2, corresponding to the identification information, as the modulated carrier wave to which the identification information has been assigned. The multiplier 414 then outputs this modulated carrier wave, to which the identification information has been assigned, to the amplifier circuit 415 as the transmit signal, which serves as the basis of the transmit wave.

[0075] The amplifier circuit 415 amplifies the transmit signal output from the multiplier 414 and outputs the amplified transmit signal to the wave transmitter 411.

[0076] The configuration of the receiving side is briefly described below.

[0077] The wave receiver 421 is configured from the vibration generation device 221 described above. Using the vibration generation device 211, the wave receiver 421 receives the transmitted wave reflected by the object as the receiving wave.

[0078] The amplifier circuit 422 amplifies a received signal, which acts as a signal corresponding to the received wave received by the wave receiver 421.

[0079] The filter processing section 423 performs filter processing on the received signal, which has been amplified by the amplifier circuit 422, and suppresses interference.

[0080] The frequency analysis section 424 performs a frequency analysis (a spectral analysis), for example based on an FFT (Fast Fourier Transform), on the received signal that has undergone processing by the filter processing section 423. The frequency analysis section 424 then detects a frequency at which the signal level of the received wave reaches a peak value equal to or greater than, for example, a threshold value.

[0081] As described above, in the exemplary embodiment, the identification information of the transmitted wave has been added or assigned based on frequency modulation, and the identification information is not normally lost due to reflection. Accordingly, by determining or assessing a similarity in the identification information of the transmitted wave and the received wave to each other, the received wave, acting as the transmitted wave that has been reflected by the target object and then returned, can be detected with high accuracy.

[0082] In this respect, for example, in a case where the transmitted wave returns as a received wave under conditions that the frequency change due to the Doppler shift does not occur, the wave receiver 421 receives the received wave, which is formed from wave motions whose number and frequencies are the same as those of the wave motions forming the transmitted wave, and thus the same identification information is obtained from the received wave, with the identification information being the same as the identification information of the transmitted wave. In this case, the received wave is suitable as a target for the similarity assessment of the identification information between the received wave and the transmitted wave without any correction being performed.

[0083] However, as will be described in detail later, in a case where the transmitting wave returns as the received wave under conditions where a frequency shift occurs due to the Doppler shift, the frequencies (and number) of wave motions forming the received wave picked up by the wave receiver 421 and the frequencies (and number) of wave motions forming the transmitting wave do not match or align due to the influence of the frequency shift. Therefore, the identification information, which is the same as the identification information of the transmitting wave, cannot be obtained from the received wave unless a correction is made to eliminate the influence of the frequency shift.Consequently, in this case, the magnitude of the frequency change caused by the Doppler shift must be estimated in order to determine an appropriate degree of correction to be applied to the receiving wave.

[0084] According to the exemplary embodiment, the estimating section 425, based on a result of the frequency analysis performed by the frequency analysis section 424 and transmit frequency information that specifies a relationship between the frequencies of the wave motions forming the transmitting wave, identifies a correspondence relationship between the frequencies of the wave motions forming the receiving wave and the frequencies of the wave motions forming the transmitting wave, and estimates the magnitude of the frequency change due to the Doppler shift based on a difference between the corresponding frequencies, in a method that is described later. For example, the transmit frequency information corresponds to information specifying the width of an interval between the frequencies (for example, the center frequencies f1 and f2 in the Fig. 5 illustrated example), in which signal levels of the transmitting wave reach peak values, and / or have the center frequency fc of the predetermined frequency band FB in which the vibration generating device 211 can transmit and receive the waves.

[0085] For example, in a case where the transmitted wave returns as the received wave under the conditions that the Doppler shift does not occur, as described above, the wave receiver 421 receives the received wave, which is formed from wave motions whose number and frequencies are the same as those of the wave motions forming the transmitted wave. In such a case, the estimating section 425 receives the number and frequencies of the wave motions forming the received wave, according to the result of the frequency analysis by the frequency analysis section 424. The estimating section 425 also receives the number and frequencies of the wave motions forming the transmitted wave, according to the transmit frequency information.Then, based on the coincidence or agreement in the frequencies of the wave motions forming the received wave and the wave motions forming the transmitted wave, the estimation section estimates that the magnitude of the frequency change due to the Doppler shift is zero.

[0086] Even in a case where a frequency shift occurs due to the Doppler shift, if the magnitude of the frequency shift is relatively small, the wave receiver 421 receives the received wave, which is formed from wave motions whose number is the same as the number of wave motions forming the transmitted wave, although the frequencies of the wave motions of the received wave are shifted with respect to the frequencies of the wave motions of the transmitted wave, as described in Fig. Figure 7 illustrates this.

[0087] Fig. Figure 7 shows a schematic example diagram illustrating an example of the frequencies of the received wave according to the embodiment. More precisely, this corresponds to the diagram in Fig. Example 7 illustrates the result of the frequency analysis performed by the frequency analysis section 424 on the received wave, which is received by the wave receiver 421 as a result of the fact that the transmitted wave, which is formed from wave movements of the two frequencies within the ranges of bands B1 and B2, which is in Fig. 5 are illustrated, through which the light is reflected by the object, in a case where the magnitude of the frequency shift due to the Doppler shift is relatively small. In the case shown in Fig. In the illustrated example 7, the horizontal axis indicates a frequency and the vertical axis indicates a signal level (for example, PSD, that is, a power spectral density).

[0088] In the Fig. In the illustrated example 7, a relatively small change towards a higher frequency occurs due to the Doppler shift. A band B11 (a center frequency f11), which in Fig. The value given in 7 corresponds to a result of the change in band B1 (the center frequency f1), which is in Fig. 5 is specified, towards the high-range side, and corresponds to a band B12 (a center frequency f12), which is in Fig. Figure 7 shows a result of the change in band B2 (the center frequency f2), which is shown in Fig. 5 is shown, towards the high area side.

[0089] As it is in Fig. As illustrated in Figure 7, in a case where the magnitude of the frequency shift caused by the Doppler shift is relatively small, the frequencies of both of the two wave motions (which is the same as the number of wave motions forming the transmitting wave) exist within the range of the predetermined frequency band FB according to the specifications of the vibration-generating device 211. In such a case, it is clear that a correspondence relationship exists between the frequencies of the respective wave motions forming the transmitting wave and the frequencies of the respective wave motions forming the receiving wave, with the frequencies on the higher-range side corresponding to each other and the other frequencies on the lower-range side corresponding to each other in the correspondence relationship.Accordingly, estimating section 425 identifies the frequency correspondence between the wave motions forming the received wave and the wave motions forming the transmitted wave, as described above. Then, estimating section 425 estimates a difference between the corresponding frequencies (that is, a difference between the frequencies on the lower range side or a difference between the frequencies on the higher range side) as the magnitude of the frequency change.

[0090] As described above, in a case where the number of frequencies of the wave motions forming the received wave and the number of frequencies of the wave motions forming the transmitted wave are equal to each other, estimation section 425 identifies the correspondence relationship between the frequencies of the former and the frequencies of the latter on the basis of a correspondence between the frequencies of the former and the frequencies of the latter with each other, or on the basis of a correspondence between a magnitude relationship (a high-and-low relationship) between the frequencies of the former and a magnitude relationship (a high-and-low relationship) between the frequencies of the latter with each other.Then, based on the identified correspondence relationship, estimation section 425 estimates the difference between the frequencies that correspond to each other from the frequencies of the former and the frequencies of the latter, estimation section 425 estimating the difference as the magnitude of the frequency change due to the Doppler shift.

[0091] In contrast, in a case where the relative speed of vehicle 1 and the target object is greater than that specified in the Fig. 7 illustrated state, and thus the magnitude of the frequency change due to the Doppler shift becomes relatively large, the wave receiver 421 the received wave, which is formed from the wave motions whose frequencies are shifted with respect to the wave motions that form the transmitted wave, and whose number is less than the number of wave motions that form the transmitted wave, as is shown in Fig. Figure 8 illustrates this.

[0092] Fig. Figure 8 shows a schematic example diagram illustrating another example of the frequency of the received wave according to the embodiment. More precisely, this corresponds to the Fig. 8 illustrated example the result of the frequency analysis performed by the frequency analysis section 424 on the received wave received by the wave receiver 421 in a case where the magnitude of the frequency change due to the Doppler shift is relatively large, as a result of the transmitted wave being formed from the wave motions of two frequencies within the ranges of bands B1 and B2, which in Fig. 5 are illustrated, through which the object is reflected. In which in Fig. In the illustrated example 8, the horizontal axis indicates a frequency, and the vertical axis indicates a signal level (for example, PSD, i.e., a power spectral density).

[0093] In the Fig. In the illustrated example 8, a relatively large change in frequency towards the high-frequency side occurs due to the Doppler shift. A Fig. Band B21 (a center frequency f21), illustrated in section 8, corresponds to a result of the change in Fig. 5 illustrated band B1 (the center frequency f1) to the high-range side, and one in Fig. Band B22 (a center frequency f22), illustrated in section 8, corresponds to a result of the change in Fig. 5 illustrated band B2 (the center frequency f2) towards the high-range side.

[0094] According to the exemplary embodiment, the wave receiver 421 can only receive a wave motion whose frequency lies within the range of the predetermined frequency band FB, which is set depending on the specifications of the vibration generation device 211. In contrast, in the Fig. In example 8, the center frequency f21 of band B21 is located between the lower cutoff frequency fa and the upper cutoff frequency fb of the predetermined frequency band FB. However, the center frequency f22 of band B22 is shifted towards the high-frequency side with respect to the upper cutoff frequency fb of the predetermined frequency band FB. Accordingly, in the Fig. Example 8 illustrates that the wave motion of the frequency within the range of frequency band B21 is received in a normal manner, however, the wave motion of the frequency within the range of band B22 is not received in a normal manner. Consequently, it appears that in the Fig. The 8 illustrated example shows that it can be difficult to identify the correspondence relationship between the frequency of the wave motion of the one frequency that is received in the normal way and the frequencies of the wave motions of the two frequencies that form or configure the transmitted wave.

[0095] However, a relationship between volume B21 and volume B22, which is in Fig. Figure 8 illustrates (for example, an interval between the center frequencies f21 and f22) and a relationship between band B1 and band B2, which is shown in Fig. 5 illustrates (for example, an interval between the center frequencies f1 and f2) that agree with each other regardless of whether the Doppler shift occurs or not. Based on this, even in such a case, which is in Fig. In equation 8, where the transmitting wave is formed from the wave motions of the two frequencies, but the received wave, which is formed from the wave motion of one frequency, is received in a normal way, it is determined which of the frequencies of the two wave motions forming the transmitting wave corresponds to the frequency of the one wave motion forming the received wave.

[0096] More precisely, it should be in the Fig. 8 illustrated example, assuming that the frequency which lies within the range of band B21 corresponds to the frequency which lies within the range of the in Fig. The band B2 in the 5 illustrated diagram is a band that indicates the signal level, similar to that in Fig. Band B1, as illustrated in section 5, exists within the range of the predetermined frequency band FB on the lower side of the range than band B21. In the section shown Fig. However, in the illustrated example 8, the lower side of the range with respect to band B21 within the predetermined frequency band FB is an empty band X. Consequently, in the Fig. Example 8 illustrates that the frequency which lies within the range of band B21 can be identified as corresponding to the frequency which lies within the range of band B1, which is in Fig. 5 is illustrated.

[0097] More precisely, in a case where the center frequency f21 of band B21 is determined within the range of the predetermined frequency band FB as a result of the frequency analysis performed by the frequency analysis section 424, the estimation section 425 identifies a magnitude relationship between an interval from the center frequency f21 to the upper cutoff frequency fb and another interval from the center frequency f1 to the center frequency f2, the frequencies of the two wave motions that form the transmitted wave. This other interval between the center frequency f1 and the center frequency f2 corresponds to 2 × Δf (see Fig. 5) And estimation section 425 identifies a magnitude relationship between one interval from the center frequency f21 to the lower cutoff frequency fa and the other interval 2 × Δf. Thus, estimation section 425 identifies a direction of the change in frequencies due to the Doppler shift, that is, a position of the empty band X.

[0098] For example, in the Fig. In the example illustrated in Figure 8, the interval between the center frequency f21 and the upper cutoff frequency is less than 2 × Δf, and the interval between the center frequency f21 and the lower cutoff frequency fa is greater than 2 × Δf. In such a case, estimation section 425 identifies that the wave motion, which has been transmitted using band B2 such that the signal level reaches its peak value at the center frequency f2 (see Figure 8). Fig. 5) as a result of the frequency change due to the Doppler shift, it has come to exhibit a frequency that is higher than the upper cutoff frequency FB of the predetermined frequency band FB, and consequently corresponds to the wave motion that is actually undetectable as the wave motion that forms the received wave. That is to say, in such a case, estimation section 425 identifies that the empty band X exists between the center frequency f21 of band B21, which is actually detected in the range of the predetermined frequency band FB, and the lower cutoff frequency fa.

[0099] In contrast, if it is assumed that an interval between a frequency actually detected in the range of the predetermined frequency band FB as a result of the frequency analysis performed by the frequency analysis section 424 and the upper cutoff frequency FB is greater than 2 × Δf, and an interval between the frequency described above and the lower cutoff frequency fa is less than 2 × Δf, the estimation section 425 identifies that the wave motion transmitted by using band B1 such that the signal level reaches its peak value at the center frequency f1 (see Fig. 5) as a result of the frequency change due to the Doppler shift, a frequency has come to be exhibited that is lower than the lower cutoff frequency fa of the predetermined frequency band FB, and consequently corresponds to the wave motion that is undetectable as the wave motion that forms the received wave. That is to say, in such a case, estimation section 425 identifies that the empty band exists between the one frequency that is actually detected in the range of the predetermined frequency band FB and the upper cutoff frequency.

[0100] As described above, according to the exemplary embodiment, in a case where the number of frequencies of the wave motions forming the received wave and the number of frequencies of the wave motions forming the transmitted wave differ from each other, the estimating section 425 identifies the correspondence relationship between the frequencies of the wave motions forming the received wave and the frequencies of the wave motions forming the transmitted wave, according to the empty band that exists in the range with lower frequencies and / or the range with higher frequencies than the frequency of the wave motion that is actually detected as the wave motion forming the received wave within the range of the predetermined frequency band FB.Then, based on the identified correspondence relationship, estimation section 425 estimates the difference between the corresponding frequencies of the wave motions forming the received wave and the frequencies of the wave motions forming the transmitted wave. Estimation section 425 estimates this difference as the magnitude of the frequency shift due to the Doppler shift.

[0101] A method for identifying the empty band (the position of the empty band) is not limited to the method described above. For example, another method for identifying the empty band is to identify the empty band based on which frequency actually captured within the predetermined frequency band FB is closest to the lower cutoff frequency fa and the upper cutoff frequency FB.

[0102] The identification of the empty tape is also effective in the case of the Fig. The illustrated example 7 is applicable where the degree (the extent) of the Doppler shift is smaller than in the one described in Fig. The example in point 8 illustrates this. By identifying the empty tape in which the Fig. By comparing the sizes of the respective empty bands that exist on both the low-range and high-range sides with respect to the two frequencies that are actually captured as the frequencies of the wave motions that form the received wave, the direction of the frequency change can be identified and the correspondence relationship between the frequencies of the wave motions that form the received wave and the frequencies of the wave motions that form the transmitted wave can be identified.

[0103] According to Fig. 4. Correction section 426, based on the estimation result performed by estimation section 425, corrects the frequency of the wave motion, which is recorded as the wave motion that forms the received wave (the received signal), in such a way as to establish consistency with the frequency of the transmitted wave (the transmitted signal).

[0104] Based on, for example, the transmitted signal, which is contained according to the configuration of the transmitting side, and the received signal after correction by the correction section 426, the correlation processing section 427 obtains a correlation value that corresponds to a degree (a measure) of similarity between the identification information of the transmitted wave and the identification information of the received wave. The correlation value is calculated, for example, based on a known correlation function.

[0105] The envelope processing section 428 receives an envelope of a waveform of the signal corresponding to the correlation value obtained by the correlation processing section 427.

[0106] The threshold processing section 429 compares a value of the envelope obtained by the envelope processing section 428 with a predetermined threshold and determines, based on the comparison result, whether the identification information of the received wave is similar to each other at a level equal to or greater than a predetermined level.

[0107] Based on a processing result by the threshold processing section 429, the detection section 430 identifies a point in time at which the degree of similarity between the identification information of the transmitting wave and the receiving wave is at a level equal to or greater than the predetermined level, that is, a point in time (for example, the one in Fig. 2 specified time t4), at which the signal level of the received wave, which acts as the transmitted wave which is returned due to reflection, reaches the peak value which exceeds the threshold, and the detection section 430 detects the distance to the object by the TOF method.

[0108] In a situation where vehicle 1 is approaching or getting close to the object, the need to determine the distance to the object is greater than in a situation where vehicle 1 is moving away from the object. Generally, when vehicle 1 is approaching the object, the intermittently continuous multiple wave motions that form the transmitted wave revert to a state where the frequencies of the respective wave motions have shifted or transitioned to the high-frequency side in response to reflection as a result of the frequency change due to the Doppler shift.Accordingly, in the situation where vehicle 1 approaches the object, of the multiple wave motions forming the transmitted wave, the wave motion whose frequency is on the high-frequency side is not easily identified as the wave motion that lies within the predetermined frequency band FB when it returns due to reflection. That is to say, in the situation where vehicle 1 approaches the object, if the multiple wave motions forming the transmitted wave contain more wave motions with frequencies on the high-frequency side than wave motions with frequencies on the low-frequency side, the number of wave motions that are correctly identified is likely to be small. Consequently, the accuracy in determining the similarity between the identification information of the transmitted wave and the identification information of the received wave is likely to be reduced.

[0109] Accordingly, in the exemplary embodiment, the temporarily (in a time-based manner) continuous multiple wave motions that shape the transmitted wave are effectively configured such that they exhibit more wave motions of the frequencies on the low-band side than wave motions of the frequencies on the high-band side, so that more of the waveforms that shape the received wave can be detected even in the situation where the vehicle 1 is approaching the object. That is to say, in the exemplary embodiment, as in the example of Fig. Figure 6 illustrates that it is effective to shape or configure the transmitting wave such that it has more of the first wave movements W1 of the first frequency on the low-range side than the second wave movement W2 of the frequency on the high-range side, that is to say, it is effective to set the identification information such that it contains more codes of the bit of 1 than the code of the bit of 0.

[0110] The following describes a processing sequence that is carried out according to the exemplary embodiment.

[0111] Fig. Figure 9 shows a schematic example flowchart indicating a processing sequence that is carried out by the distance detection device 200 according to the embodiment for acquiring information relating to the object.

[0112] As it is in Fig.As illustrated in Figure 9, according to the embodiment S901, the wave transmitter 411 first sends the transmitting wave outside the vehicle 1 in accordance with the transmit signal generated by the code generation section 412, the carrier wave output section 413, the multiplier 414 and the amplifier circuit 415. More precisely, based on the frequency modulation that uses the two frequencies of the two bands configured, for example, via the band division described above, the wave transmitter 411 sends the transmitting wave, which is coded to have the identification information of the predetermined code length, the temporarily continuous wave movements including the combination of the first wave movement W1 and the second wave movement W2.

[0113] In S902, the wave receiver 421 receives the received wave, which acts as the transmitted wave that was reflected by the object located outside the vehicle 1 and consequently returned to the vehicle 1. The received signal, corresponding to the received wave, is amplified by the amplifier circuit 422 and then output to the filter processing section 423.

[0114] In S903, the filter processing section 423 performs filter processing on the amplified received signal, which has been amplified by the amplifier circuit 422, thereby reducing or suppressing the interference.

[0115] In S904, the frequency analysis section 424 performs the frequency analysis (the spectral analysis), for example, based on FFT (the fast Fourier transform), on the received signal that has undergone filter processing by the filter processing section 423. This identifies the number and frequencies of the wave motions that constitute the received wave.

[0116] In S905, the estimating section 425 identifies, on the basis of the frequencies of the wave motions forming the received wave, which are obtained as a result of the frequency analysis carried out in S904, and on the basis of the transmit frequency information which specifies the relationship between the several (in this embodiment two) frequencies that form the transmit wave, the correspondence relationship between the frequencies of the wave motions forming the received wave and the frequencies of the wave motions forming the transmit wave, and estimates the difference between the frequencies that correspond to each other as the magnitude of the frequency change due to the Doppler shift.The procedure for identifying the correspondence relationship between the frequency or frequencies of the wave motion or motions forming the received wave and the frequencies of the wave motions forming the transmitted wave has been described in detail above, so an explanation of the procedure is omitted here.

[0117] In S906, the correction section 426, based on the determination or estimation result by the estimation section 425, corrects the frequency of the wave motion, which is captured as the wave motion that forms the received wave (the received signal), such that consistency is established between the frequencies of the received wave (the received signal) and the transmitted wave (the transmitted signal).

[0118] In S907, for example, the correlation processing section 427 performs the correlation processing of obtaining the correlation value, which corresponds to the degree of similarity of the respective identification information of the transmitting wave and the receiving wave, based on the transmit signal received from the transmitting side configuration and the received signal on which the correction has been performed by the correction section 426.

[0119] In S908, the acquisition section 430, based on the result of the correlation processing in S907, determines the distance to the object that causes the reflection of the transmitted wave.

[0120] More precisely, in S908, the acquisition section 430 first receives from the threshold processing section 429 the result of the comparison between the correlation value at which the processing was performed by the envelope processing section 428 and the threshold value. Then, based on the information received from the threshold processing section 429, the acquisition section 430 identifies the time at which the transmitting wave was sent and the time at which the receiving wave was received. The receiving wave is assigned identification information that is similar to (corresponding to) the transmitting wave at a level equal to or greater than the predetermined level, and this information serves as the basis for the corrected receiving wave.Then, based on the difference between the two time points, the detection section 430 determines the distance to the object reflecting the transmitted signal using the TOF method. The process then ends.

[0121] As described above, the distance detection device 200, according to the exemplary embodiment, comprises the wave transmitter 411, the wave receiver 421, the estimating section 425, the correction section 426, and the detection section 430. The wave transmitter 411 transmits the transmit wave based on the two frequencies set within the range of the predetermined frequency band FB. The wave receiver 421 receives the received wave based on the transmitted wave, which is reflected back from the object. Based on the result of the frequency analysis of the received wave and the transmit frequency information, which specifies the relationship between the two frequencies of the transmitted wave, the estimating section 425 estimates the magnitude of the frequency shift that has occurred between the transmitted wave and the received wave due to the Doppler shift.Based on the estimation result of estimation section 425, correction section 426 corrects the received wave such that frequency consistency is established between the received wave and the transmitted wave. Detection section 430 detects the distance to the object as information relating to the object, based on the relationship between the transmitted wave and the corrected received wave, which has been corrected by correction section 426.

[0122] According to the configuration described above, even in a case where the frequency change is caused by the Doppler shift, the received wave is corrected in such a way that the influence of the frequency change is eliminated, and thus the received wave, which acts as the transmitted wave that has been reflected by the target object and returned, is accurately detected, and thus the distance to the object is accurately detected as the information relating to the object.

[0123] According to the exemplary embodiment, the wave transmitter 411, as the transmitting wave, sends the temporarily continuous multiple wave movements, including the combination of the at least two wave movements, whose signal levels reach their respective peak values ​​at the at least two frequencies. The estimation section 425 then identifies the correspondence between the one or more frequencies at which the signal level of the received signal reaches its peak value and the at least two frequencies of the transmitting wave, based on the result of the frequency analysis performed by the frequency analysis section 424 and the transmitting frequency information, and estimates the magnitude of the frequency change based on the difference between the corresponding frequencies.According to the configuration described above, the magnitude of the frequency change can be easily estimated according to the correspondence relationship between the frequencies of the receiving wave and the frequencies of the transmitting wave, the correspondence relationship being identified based on the result of the frequency analysis and the transmitting frequency information.

[0124] According to the embodiment, in a case where the number of one or more frequencies of the receiving wave and the number of at least two frequencies of the transmitting wave are equal to each other, the estimating section 425 identifies the correspondence relationship between the one or more frequencies of the received signal and the at least two frequencies of the transmitting wave on the basis of the correspondence between the one or more frequencies of the receiving wave and the at least two frequencies of the transmitting wave, or on the basis of the correspondence between the magnitude relationship between the one or more frequencies of the receiving wave and the magnitude relationship between the at least two frequencies of the transmitting wave.According to the configuration described above, in a case where the magnitude of the frequency change caused by the Doppler shift is so small that the number of one or more frequencies of the receiving wave and the number of at least two frequencies of the transmitting wave coincide, the correspondence relationship of the frequencies can be easily identified by considering the correspondence of the frequencies of the receiving wave and the transmitting wave with each other or the correspondence of the magnitude relationships of the frequencies of the receiving wave and the transmitting wave with each other.

[0125] According to the embodiment, in a case where the number of one or more frequencies of the receiving wave and the number of at least two frequencies of the transmitting wave differ from each other, the estimating section identifies the correspondence relationship between the one or more frequencies of the receiving wave and the at least two frequencies of the transmitting wave on the basis of the empty band that exists on the low-range side and / or the high-range side with respect to the one or more frequencies of the receiving wave within the range of the predetermined frequency band FB.According to the configuration described above, even in a case where the magnitude of the frequency change caused by the Doppler shift is so large that the number of one or more frequencies of the receiving wave and the number of at least two frequencies of the transmitting wave do not match, the correspondence relationship between the frequencies can be easily identified by taking the empty band into account.

[0126] According to the exemplary embodiment, the at least two wave movements are each associated with information that differs from one another, such that the multiple temporarily continuous wave movements are encoded to contain predetermined identification information, and the wave transmitter 411 sends the encoded multiple temporarily continuous wave movements as the transmitting wave. According to the configuration described above, it can be easily identified, using the identification information, whether the received wave corresponds to the transmitted wave reflected by the object that serves as the detection target and then returned.

[0127] According to the exemplary embodiment, the distance sensing device 200 further comprises the correlation processing section 427, which receives the correlation value corresponding to the degree of similarity between the transmitted wave and the corrected received wave. Based on the comparison of the correlation value and the threshold value, the sensing section 430 detects the distance to the object in a case where the degree of similarity between the transmitted wave and the corrected received wave is determined to be at a level equal to or greater than the predetermined level, with the distance to the object serving as the information relating to the object. According to the configuration described above, the received wave can be correctly detected using the correlation value as the transmitted wave that has been reflected by the target object and then returned.This allows the distance to the object to be measured with accuracy.

[0128] According to the exemplary embodiment, the sensing section 430 acquires the distance to object O based on the difference between the time the transmitting wave was sent and the time the receiving wave was received. The degree of similarity of the received wave to the transmitted wave is determined to be at a level equal to or greater than a predetermined level, and this level serves as the basis for the corrected receiving wave. According to the configuration described above, the distance to the object can be easily acquired.

[0129] According to the exemplary embodiment, the at least two frequencies of the transmitting wave are each set within the ranges of the at least two bands formed by virtually subdividing the predetermined frequency band FB, and the two bands do not overlap. According to the configuration described above, the at least two frequencies of the transmitting wave can be easily set by band subdivision.

[0130] According to the exemplary embodiment, the wave transmitter 411 and the wave receiver 421 are integrally configured as the transmitting and receiving section 210 with the single vibration generating unit 211, which is configured for transmitting and receiving the sound waves. The predetermined frequency band FB is set according to the specifications of the vibration generating unit 211. According to the configuration described above, the configuration for receiving the received wave and transmitting the transmitted wave can be simplified, and the predetermined frequency band FB can be easily set. Variations

[0131] According to the embodiment described above, the technology according to the disclosure is applied in the configuration that acquires the information relating to the object by sending and receiving the ultrasonic wave; however, the disclosure is also applicable to a configuration that acquires the information relating to the object by sending and receiving a wave motion other than the ultrasonic wave, including, for example, a sound wave, a millimeter wave and / or an electromagnetic wave.

[0132] According to the embodiment described above, the disclosed technique is described as an example applicable to the distance detection device that detects the distance to the object; however, the technique according to the disclosure is also applicable to an object detection device that merely detects whether the object exists or not, that is, detects the presence or absence of the object, which serves as the information relating to the object.

[0133] According to the embodiment described above, the example configuration is two bands configured via the band division, and the frequency waveform of each band is associated with the information 0 or 1. However, the number of bands configured via the band division can be three or more. In this case, the frequency waveform of each band can be associated with information other than 0 or 1.Even in a case where the number of bands configured by subdividing the bands is three or more than three, the method for identifying the correspondence relationship of frequencies between the wave motions forming the transmitting wave and the wave motions forming the receiving wave is essentially the same as in the embodiment described above, and therefore its detailed description is omitted.

[0134] According to the embodiment described above, the entirety of the predetermined frequency band in which transmission and reception of waves by the vibration-generating device is permitted is virtually or imaginarily divided into two bands. However, a subject for the band division can be a part of the predetermined frequency band in which transmission and reception of waves by the vibration-generating device is permitted.

[0135] The exemplary configuration described above is one in which the assignment of identification information is achieved solely on the basis of frequency modulation. However, the assignment of identification information can also be achieved through a combination of frequency modulation and another modulation, including, for example, phase modulation and / or amplitude modulation.

Claims

[1] Object detection device (200, 201, 202, 203, 204) with: a transmitting section (411) configured to transmit a wave based on at least two frequencies (f1, f2) set within a range of a predetermined frequency band (FB), a receiving section (421) configured to receive a receiving wave based on the transmitted wave returned in response to a reflection from an object (O), an estimation section (425) configured to estimate the magnitude of a frequency change due to a Doppler shift between the transmitting wave and the receiving wave based on the result of a frequency analysis on the receiving wave and transmitting frequency information that specifies a relationship between the at least two frequencies of the transmitting wave, a correction section (426) configured to correct the received wave to obtain frequency consistency with the transmitted wave based on an estimation result of the estimation section (425), and a detection section (430) which is configured to detect information relating to the object (O) based on a relationship between the transmitted wave and the corrected received wave which has been corrected by the correction section (426). [2] Object detection device (200, 201, 202, 203, 204) according to claim 1, wherein the transmitting section (411) as the transmitting wave sends a multitude of temporarily continuous wave movements, which exhibit a combination of at least two wave movements (W1, W2), whose signal levels reach peak values ​​at the at least two frequencies (f1, f2) respectively, and The estimation section (425) identifies a correspondence relationship between one or more frequencies (f11, f12, f21, f22) at which a signal level of the received wave reaches a peak value, and the at least two frequencies of the transmitted wave, based on the result of the frequency analysis and the transmit frequency information, and estimates the magnitude of the frequency change based on a difference between the frequencies that correspond to each other. [3] Object detection device (200, 201, 202, 203, 204) according to claim 2, wherein the estimating section (425) in a case in which a number of the one frequency or the multiple frequencies (f11, f12) of the receiving wave and a number of the at least two frequencies (f1, f2) of the transmitting wave are equal to each other, identifies the correspondence relationship between the one frequency or the multiple frequencies (f11, f12) of the receiving wave and the at least two frequencies (f1, f2) of the transmitting wave on the basis of a correspondence between the one frequency or the multiple frequencies (f11, f12) of the receiving wave and the at least two frequencies (f1, f2) of the transmitting wave with each other or on the basis of a correspondence between a magnitude relationship between the one frequency or the multiple frequencies (f11, f12) of the receiving wave and a magnitude relationship between the at least two frequencies (f1, f2) of the transmitting wave with each other. [4] Object detection device (200, 201, 202, 203, 204) according to claim 2 or 3, wherein in a case where a number of the one frequency or the multiple frequencies (f21, f22) of the receiving wave and a number of the at least two frequencies (f1, f2) of the transmitting wave differ from each other, the estimating section (425) identifies the correspondence relationship between the one frequency or the multiple frequencies (f21, f22) of the receiving wave and the at least two frequencies (f1, f2) of the transmitting wave on the basis of an empty band (X) that exists on a low-range side and / or a high-range side with respect to the one frequency or the multiple frequencies (f21, f22) of the receiving wave within the range of the aforementioned frequency band (FB). [5] Object detection device (200, 201, 202, 203, 204) according to one of claims 2 to 4, wherein the at least two wave movements (W1, W2) are each associated with information that differs from each other in such a way that the plurality of wave movements are coded to have predetermined identification information, and the transmitting section (411) as the transmitting wave transmits the coded plurality of wave movements. [6] Object detection device (200, 201, 202, 203, 204) according to any one of claims 1 to 5, further comprising: a correlation processing section (427) configured to obtain a correlation value corresponding to a degree of similarity between the transmitted wave and the corrected received wave, wherein The acquisition section (430) acquires information relating to the object (O) on the basis of a comparison result of the correlation value and a threshold value in a case where the degree of similarity between the transmitted wave and the corrected received wave is determined to be at a level equal to or greater than a predetermined level. [7] Object detection device (200, 201, 202, 203, 204) according to claim 6, wherein the detection section (430) detects the information relating to the object (O) as a distance to the object (O) based on a difference between a time (t0) at which the transmitting wave was sent and a time (t3) at which the received wave, which serves as a basis for the corrected received wave, the degree of similarity of which with respect to the transmitting wave is determined to be at the level which is equal to or greater than the predetermined level, was received. [8] Object detection device (200, 201, 202, 203, 204) according to any one of claims 1 to 7, wherein the at least two frequencies (f1, f2) of the transmitting wave are each set within areas of at least two bands (B1, B2) formed by virtual subdivision of the predetermined frequency band (FB), and the at least two bands (B1, B2) do not overlap. [9] Object detection device (200, 201, 202, 203, 204) according to any one of claims 1 to 8, wherein the transmitting section (411) and the receiving section (421) are integrally configured together as a transmitting and receiving section (210) with a single vibration generating device (211) configured to transmit and receive a sound wave, and the predetermined frequency band (FB) is set according to the specifications of the vibration generation device (211).

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