JP2005106478A - Object detection device and system, and object detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an object detection device, object detection system, and object detection method not only capable of detecting a distance to the object but also capable of correctly discriminating whether the object is a living thing or not, and capable of giving a highly reliable warning by giving a serious warning to a user if it is a living thing. <P>SOLUTION: The object detection device can no only detect the distance to the object existing around the same but also can determine whether the object is the living thing or not, by transmitting transmission signals, and analyzing the time serial difference value of the reflection signals and the frequency components. By using this result, reliable warning is ensured by giving the serious warning if the object is the living thing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an object detection device, an object detection system, and an object detection method, and more particularly to an object detection device, an object detection system, and an object detection method for identifying an object using a reflected wave of a transmitted signal. .

  2. Description of the Related Art Conventionally, a system has been developed that measures a distance to an object existing around a vehicle and warns a driver or controls the operation of the vehicle according to the distance. As an object detection device used in the above system, a radar using a millimeter wave band or a laser, a sonar using an ultrasonic wave, or the like is used. For example, the former is mainly for the purpose of measuring the inter-vehicle distance with the preceding vehicle, and the latter is mainly for the purpose of confirming a rear collision when the vehicle is moved backward.

  On the other hand, in recent years, when starting a vehicle, there has been a problem of accidents involving a small child in a blind spot area by mistake. Especially at the time of departure, it leads to a miserable accident involving a child who is accidentally in contact with his or her child, and the truck has a large blind spot and a space where children want to dive and play. As a result, many accidents occur. Along with the increasing needs for pedestrian safety as described above, in addition to the function of detecting objects and measuring the distance from the vehicle, a function for distinguishing between living and non-living objects has been added. It is hoped to do. For example, there is a demand for a device that warns a driver when the object detection device discriminates a living organism such as a human body and a non-living organism and detects a living organism near the vehicle. This is because if the system merely warns that there are objects around the vehicle, the warning frequently occurs in an environment where the parking space is small and the reliability of the warning cannot be obtained. Therefore, in addition to the function of detecting an object and measuring the distance from the vehicle, the object detection device is desired to have a function of discriminating between living things and non-living things.

  As a radar for identifying an object, a spatial frequency of an identification target is stored in advance and compared with an input frequency to identify the target (see, for example, Patent Document 1), or a signal in the time-frequency domain using an ultra-wideband signal. From the analysis, there is one that classifies objects based on library data (for example, see Patent Document 2). Hereinafter, a conventional object classification method disclosed in Patent Document 2 will be described with reference to FIG. FIG. 16 is a block diagram for explaining the object classification method.

  In FIG. 16, preprocessing 101 performs processing for removing an irrelevant data amount from radar data. The detection 102 detects a signal when an object exists from the data processed in the preprocessing 101. The classification 103 classifies the object by calculating the feature of the object and comparing it with the reference library 104. The display 105 displays the detected object and to which class the object belongs.

Further, there is a method of detecting a human body by extracting a change component of a signal caused by a minute operation such as breathing or beating using Doppler shift of a reflected wave (see, for example, Patent Document 3).
Japanese Unexamined Patent Publication No. 62-134583 JP 2000-514921 A JP 09-228679 A

  However, when the object detection device detects an object using radio waves, the usable frequency is regulated by law, and thus the defined frequency band does not necessarily have a characteristic specific to living things. Absent. For example, the frequency bands that can be used for detecting objects around the vehicle are the 77 GHz band and the 24 GHz band, and it is difficult to say that these have specific characteristics such as absorption with respect to living things. In addition, ultrasonic waves and lasers do not have characteristics specific to living organisms in a practically usable band. Therefore, an object detection apparatus using these media can measure the distance and speed from the object, but it is often difficult to identify whether the object is a living thing.

  Further, when the object detection device uses Doppler shift, the change component for distinguishing whether the object is a human body is very small and cannot be used in a noisy environment. Furthermore, since the change component is minute, a component for detecting the change component is expensive. In addition, when the object detection device needs to measure the distance to the object, it is necessary to add a separate component for distance measurement, and how close the detected object is to the vehicle. I can't get information.

  Therefore, the present invention aims not only to detect the distance to an object, but also to provide object detection that accurately identifies and judges whether or not the object is a living thing, and further, the object detection result is obtained. An object of the present invention is to provide an object detection device, an object detection system, and an object detection method capable of providing a highly reliable warning by giving a warning with a high warning level to a user in the case of a living thing.

  In order to achieve the above object, the present invention employs the following configuration. Note that reference numerals and the like in parentheses indicate correspondence with embodiments described later to help understanding of the present invention, and do not limit the scope of the present invention.

  The object detection device (1) of the present invention identifies surrounding objects and calculates the distance to the object. The object detection device includes a transmission / reception unit (11), a distance measurement unit (21), a storage unit (31), a time change deriving unit (32), and a determination unit (33). The transmission / reception unit up-converts and transmits a transmission signal (transmission pulse signal) having a predetermined frequency, receives the reflected signal reflected by the object, and down-converts the transmission signal. The distance measuring unit calculates the distance to the object based on the time difference from when the transmission / reception unit sends the transmission signal to when the reflection signal is received (the object detection device 1 that performs steps S11, S12, S31, and S32; Hereafter, only the step number is shown). The storage unit stores the reflection signal (reflection signal amplitude transition A) down-converted by the transmission / reception unit for a predetermined time at each timing of receiving the reflection signal (S13 to S16, S33 to S36). The time change deriving unit calculates a change distribution (distribution of difference value D, frequency component F) within a predetermined time with respect to the reflected signal stored in the storage unit (S17, S37). Based on the change distribution of the reflected signal calculated by the time change deriving unit, the determining unit determines that the object reflecting the reflected signal is a living organism (S18 to S20, S38 to S40).

  As an example, the time change deriving unit calculates a time-series difference value from the reflection signal stored in the storage unit for a predetermined time, and calculates the distribution of these difference values (S17). In this case, when the variance value of the difference value distribution calculated by the time change deriving unit is larger than a predetermined value (S18), the determining unit determines that the object reflecting the reflected signal is a living thing (S19). As another example, the time change deriving unit performs frequency conversion according to time on the reflected signal stored in the storage unit for a predetermined time, and calculates the distribution of these frequency components (S37). In this case, when the frequency component distribution calculated by the time change deriving unit includes a frequency component equal to or higher than a predetermined frequency (S38), the determination unit determines that the object reflecting the reflected signal is a living thing. (S39).

  Specifically, the transmission signal medium transmitted by the transmission / reception unit is a radio wave of 10 GHz or more. The transmission / reception unit down-converts the in-phase component (I) and the quadrature component (Q) of the reflected signal. In this case, the storage unit stores at least one of the in-phase component and the quadrature component of the reflected signal down-converted by the transmission / reception unit for a predetermined time. The time change deriving unit calculates a change distribution within a predetermined time for at least one of the in-phase component and the quadrature component of the reflected signal stored in the storage unit.

  The object detection system of the present invention performs identification of surrounding objects and calculation of the distance to the object, and outputs information corresponding to each result. The object detection system includes at least one object detection device, a control unit (warning control unit 6, centralized control unit 10), and an output unit (display unit 4, speaker 5). A control part controls the information given to a user according to the identification of the object output from an object detection apparatus, and the distance to an object. The output unit gives the information to the user based on the information controlled by the control unit. The object detection device includes a transmission / reception unit, a distance measurement unit, a storage unit, a time change derivation unit, and a determination unit. The transmission / reception unit up-converts and transmits a transmission signal having a predetermined frequency, receives the reflected signal reflected by the object, and down-converts the transmission signal. The distance measuring unit calculates a distance to the object based on a time difference from when the transmission / reception unit transmits the transmission signal to when the reflection signal is received. The storage unit stores the reflected signal down-converted by the transmission / reception unit for a predetermined time at each reception timing of the reflected signal. The time change deriving unit calculates a change distribution within a predetermined time with respect to the reflected signal stored in the storage unit. The determination unit determines that the object reflecting the reflection signal is a living organism based on the change distribution of the reflection signal calculated by the time change deriving unit. When the determination unit determines that the object is a living thing, the control unit outputs information related to the distance to the object calculated by the distance measurement unit to the output unit.

  The control unit may output warning information for the user to the output unit when the determination unit determines that the object is a living thing and the distance to the object calculated by the ranging unit is equal to or less than a predetermined distance. .

  As an example, the time change deriving unit calculates time-series difference values from the reflected signals stored in the storage unit for a predetermined time, and calculates the distribution of these difference values. In this case, the determination unit determines that the object reflecting the reflection signal is a living thing when the variance value of the distribution of the difference values calculated by the time change deriving unit is larger than a predetermined value. As another example, the time change deriving unit performs frequency conversion corresponding to time on the reflected signal stored in the storage unit for a predetermined time, and calculates the distribution of these frequency components. In this case, when the frequency component distribution calculated by the time change deriving unit includes a frequency component equal to or higher than a predetermined frequency, the determination unit determines that the object reflecting the reflected signal is a living thing.

  You may provide the several object detection apparatus (1a-1n) which each sends a transmission signal to a peculiar direction. As an example, when at least one of the determination units included in the plurality of object detection devices determines that the object is a living thing, the control unit (10) calculates the distance to the object calculated by the distance measurement unit included in the object detection device. The information about is output to the output unit. As another example, the control unit determines that at least one of the determination units included in the plurality of object detection devices determines that the object is an organism, and the distance to the object calculated by the distance measurement unit included in the object detection device is When the distance is equal to or less than the predetermined distance, warning information for the user is output to the output unit.

  Note that the present invention can also be implemented as an object detection method, similar to the object detection device and the object detection system described above.

  According to the object detection device of the present invention, by calculating the degree of change of the reflected signal with respect to a predetermined time, it is determined whether the object is a living organism such as a human body or a non-living organism such as a vehicle or a wall. It becomes possible. For example, by installing the object detection device on a moving body such as a vehicle, not only detecting the distance to an object existing around the vehicle, but also identifying a living organism such as a human body and detecting the living organism A warning or the like can be given to the driver.

  For example, the degree of change in the reflected signal is calculated by analyzing the time-series difference value and frequency component of the reflected signal, and the respective distributions are calculated. It can be easily determined whether or not is a living thing.

  Further, when the medium of the transmission signal transmitted by the transmission / reception unit is a radio wave of 10 GHz or more, the object detection device can be used even in a frequency band (24 GHz band or 77 GHz band) that can be used for object detection around the vehicle. . Further, when the storage unit stores at least one of the in-phase component and the quadrature component of the reflected signal down-converted by the transmission / reception unit for a predetermined time, the capacity for storing the reflected signal and the subsequent processing load are reduced.

  According to the object detection system of the present invention, the output result from the object detection device having the above-described effect can be used to give a display or warning from the output unit to the user only when the object is a living body such as a human body. it can. For example, by installing the object detection system on a moving body such as a vehicle, not only detecting the distance to an object existing around the vehicle, but also identifying a living organism such as a human body and detecting it It is possible to increase the value of a system that gives a driver a warning or the like, detects a living thing, and warns of the possibility of a collision. In other words, using a detection result of the object detection device, a highly reliable warning is possible by giving a warning with a high warning level to the user in the case of a living thing.

  In addition, when a plurality of object detection devices that transmit transmission signals in respective unique directions are provided, information can be controlled intensively for objects existing in a plurality of directions. For example, when an object in any direction is identified and determined as a living thing without being limited to a single direction, information corresponding to the distance can be given to the user.

  Also in the object detection method of the present invention, the same effects as those of the object detection device and the object detection system described above can be obtained.

(First embodiment)
With reference to FIG. 1, an object detection apparatus according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of the object detection apparatus.

  In FIG. 1, the object detection device 1 includes a signal processing unit 2 and a transmission / reception unit 11, and a result processed by the signal processing unit 2 is displayed on a display unit 4 configured by a liquid crystal display or the like. The signal processing unit 2 includes a computer system including a storage unit such as a memory, and includes an identification unit 3 and a distance measuring unit 21. The identification unit 3 includes a reception signal storage unit 31, a time change deriving unit 32, and a determination unit 33. The functions of these components will be described later. Typically, the object detection device 1 is installed in a vehicle as a moving body, and a transmission pulse signal (described later) transmitted from the transmission / reception unit 11 is transmitted to the outside of the vehicle.

  Next, the configuration of the transmission / reception unit 11 will be described with reference to FIG. 2. FIG. 2 is a block diagram showing the configuration when the transmission / reception unit 11 transmits and receives signals using radio waves.

  In FIG. 2, the transmission / reception unit 11 includes a clock oscillator 111, a delay circuit 112, a pulse generator 113, a local oscillator 114, a mixer 115, bandpass filters 116 and 121, a power amplifier 117, and an antenna switch 118. And an antenna 119, an LNA (Low Noise Amplifier) 120, an IQ detector 122, and an A / D converter 123.

  The transmission / reception unit 11 transmits an amplitude modulated (AM) pulse signal from the antenna 119. A pulse signal is output from the pulse generator 113 to the mixer 115 based on the clock signal managed by the clock generator 111 and the delay circuit 112. The pulse signal is mixed with an oscillation signal from a local oscillator 114 that oscillates at a predetermined frequency by a mixer 115, is up-converted, band-limited by a band filter 116, amplified by a power amplifier 117, and then passed through an antenna switch 118. And transmitted from the antenna 119 as a transmission pulse signal. For example, the transmission pulse signal transmitted from the transmission / reception unit 11 is a radio wave of 10 GHz or more. When the object detection device 1 is installed in a vehicle and is used for detecting an object around the vehicle, the transmission pulse signal uses a 24-GHz band of 77 to 29 GHz or a 77 GHz band.

  On the other hand, a signal transmitted from the antenna 119 and reflected back by an object is received as a reflected signal from the antenna 119, amplified by the LNA 120 via the antenna switch 118, and band-limited by the band filter 121. The reflected signal is detected by the IQ detector 122 into a 0 ° component (in-phase component Inphase: hereinafter referred to as data I) and a 90 ° component (quadrature component quadrature: hereinafter referred to as data Q) and down-converted. The detected data I and Q are A / D converted by the A / D converter 123.

  FIG. 3 is a diagram schematically showing the relationship between the transmission pulse signal P and the reflection signal E with the horizontal axis as time t. FIG. 3A shows the amplitude-modulated transmission pulse signal Ps and the received reflection signal Es. FIG. 3B shows the relationship between the transmission pulse signal Pt before amplitude modulation and the detected reflected signal Et. As shown in FIG. 3, the transmission pulse signal P is transmitted from the transmission / reception unit 11 at every time interval fr. The reflected signal E is received by the transmission / reception unit 11 with a time difference Δt delayed from the transmission pulse signal P. Therefore, the time difference Δt changes according to the distance from the object that reflects the transmission pulse signal P. Here, in the transmission / reception unit 11, the transmission pulse signal P and the reflected signal E cannot be in a synchronized state.

より振幅を求めることにより、反射信号Ｅｔが得られる。この反射信号Ｅｔから得られるタイミングから、時間差Δｔを得て、物体との距離を演算して、表示部４へ出力する。 Next, returning to FIG. 1, functions of the identification unit 3 and the distance measurement unit 21 will be described. As described above, in the transmission / reception unit 11, the transmission pulse signal and the reflected signal cannot be in a synchronized state. Therefore, the distance measurement unit 21 obtains the reception timing of the reflection signal using the reflection signal received by the transmission / reception unit 11, that is, both data I and Q A / D converted by the A / D conversion unit 123. Specifically, the IQ detector 122 obtains data I and data Q,

The reflection signal Et is obtained by obtaining the amplitude more. From the timing obtained from the reflected signal Et, a time difference Δt is obtained, and the distance from the object is calculated and output to the display unit 4.

  On the other hand, the reception signal storage unit 31 of the identification unit 3 receives the reflection signal received by the transmission / reception unit 11 at the reception timing after the time difference Δt from the transmission timing, that is, the data I and Q A / D converted by the A / D conversion unit 123. Is stored for each reception timing for a predetermined time. Here, the reception signal storage unit 31 does not change the reception timing, that is, when the object detection device 1 and the target object are almost stationary or the relative speed is zero, the reception timing is the predetermined time. Store every time. At this time, the data stored in the reception signal storage unit 31 may be at least one of the data I and Q.

  The time change deriving unit 32 calculates the difference value before and after the data accumulated in the received signal storage unit 31 in time series, and acquires the distribution. Then, the time change deriving unit 32 obtains a distribution based on a value normalized by the average value of the distribution. Based on the variance value from the distribution obtained by the time change deriving unit 32, the determining unit 33 identifies and determines whether or not the object is a living thing, and outputs the determination result to the display unit 4.

  Next, the processing operation of the signal processing unit 2 using the data I and Q will be described with reference to FIG. FIG. 4 is a flowchart showing the processing operation of the signal processing unit 2.

  In FIG. 4, the distance measuring unit 21 of the signal processing unit 2 detects the reception timing of the reflected signal using the data I and Q (step S11). Then, the distance measuring unit 21 calculates the distance to the object based on the time difference Δt between the transmission pulse signal and the reception timing (step S12).

  On the other hand, the reception signal storage unit 31 of the identification unit 3 holds at least one of the data I and Q for a predetermined time for each reception timing detected by the distance measurement unit 21 in step S11. Specifically, the identification unit 3 determines whether or not the previous reception timing is the same as the reception timing detected in step S11 (step S13), and when the reception timing changes, the reception signal storage unit 31 is changed. Clear and start storing new data I or Q (step S14). On the other hand, when the reception timing does not change, the data I or Q is stored in the reception signal storage unit 31 (step S15).

  5 and 6 show one of the data I and Q stored in the received signal storage unit 31 when the object detection device 1 and the target object are almost stationary or the relative speed is zero. 5 shows the reflected signal amplitude transition Aa reflected by the non-living object, and FIG. 6 shows the reflected signal amplitude transition Ab reflected by the living body. As shown in FIG. 5, when the object that reflects the transmission pulse signal is a non-living object such as a vehicle or a wall, the reflection signal amplitude transition Aa changes gently because the reflection object is fixed. On the other hand, as shown in FIG. 6, in the case of a living body such as a human body, the reflected signal amplitude transition Ab changes finely and greatly. This is because living organisms such as the human body always move minutely by breathing and beating as long as they are alive. Moreover, even if it is said that it is still, if it is a normal state (a state where it is not conscious), it is swung by a width of several mm. Therefore, the data I and Q become reflected signals whose amplitude changes finely and greatly due to the phase difference of the movement of the living thing. In order to accurately distinguish such changes, it is desirable to use radio waves of at least 10 GHz or more as transmission pulse signals because 90 degrees of a 10 GHz radio wave, that is, a quarter wavelength is 7.5 mm.

  Next, the identification unit 3 determines whether or not any IQ data for a predetermined time is stored in the reception signal storage unit 31 (step S16), and when the data for the predetermined time is not stored, Returning to step S11, the process is repeated. When stored for a predetermined time, the time change deriving unit 32 of the identifying unit 3 calculates the difference value before and after the data accumulated in the received signal storage unit 31 in time series, and analyzes the distribution (step). S17). Specifically, the time change deriving unit 32 analyzes a distribution based on a value normalized by the average value of the distribution.

  7 and 8 are graphs showing an example of the distribution of the difference value D analyzed by the time change deriving unit 32, and FIGS. 9 and 10 show the distribution of the difference value D obtained by normalizing each distribution with the average value. It is a graph which shows an example. 7 and 9 show the distribution of the difference value Da corresponding to the reflected signal amplitude transition Aa reflected by the non-living object, and FIGS. 8 and 10 show the difference value Db corresponding to the reflected signal amplitude transition Ab reflected by the living thing. Distribution. As shown in FIGS. 7 and 9, when the object that reflects the transmission pulse signal is a non-living object such as a vehicle or a wall, the reflected signal amplitude transition Aa changes gently. Get smaller. On the other hand, as shown in FIGS. 8 and 10, in the case of a living body such as a human body, the reflected signal amplitude transition Ab changes finely and greatly, so that the variance of the distribution of the difference value Db becomes large.

  Next, the determination unit 33 of the identification unit 3 determines whether or not the variance in the distribution of difference values obtained by the time change deriving unit 32 is greater than a predetermined value (step S18). If the variance is greater than the predetermined value, the determination unit 33 determines that the object is a living thing (step S19), and proceeds to the next step S18. On the other hand, when the variance is equal to or smaller than the predetermined value, the determination unit 33 determines that the object is an inanimate object (step S20), and proceeds to the next step S21.

  In step S21, the determination unit 33 outputs the object identification determination result in step S19 or S20 to the display unit 4. Then, the identification unit 3 clears the data stored in the reception signal storage unit 31 (step S22), and the determination unit 33 determines whether or not to continue object detection (step S23). If the object detection is continued, the determination unit 33 returns to step S11 to continue the process. If the object detection is to be ended, the determination unit 33 ends the process according to the flowchart.

  The display unit 4 displays the distance from the object output from the distance measuring unit 21 and the object identification determination result output from the determination unit 33. As shown in FIG. 11, a warning control unit 6 may be provided between the distance measurement unit 21 and the determination unit 33, the display unit 4, and the speaker 5. The warning control unit 6 is configured by a general computer system, and outputs warning data to the display unit 4 and the speaker 5 in accordance with respective processing results in the distance measurement unit 21 and the determination unit 33. For example, when the distance to the object calculated by the distance measuring unit 21 is equal to or less than a predetermined distance, the warning control unit 6 outputs warning data to the speaker 5 to warn the speaker 5 with voice or warn the display unit 4. The display unit 4 displays a warning by outputting the data. When the determination unit 33 identifies and determines that the object is a living body such as a human body and the distance to the object calculated by the distance measurement unit 21 is equal to or less than a predetermined distance, the warning control unit 6 displays the distance on the display unit 4. The warning data is output to the speaker 5 and the speaker 5 outputs a warning by voice, or the warning data is output to the display unit 4 and the display unit 4 displays the warning.

  As described above, according to the object detection device according to the first embodiment, not only the distance to the object existing around the object detection device is detected by calculating the time-series difference of the reflected signal. It can be determined whether or not the object is a living thing. Further, in the case of a living thing, a highly reliable warning is possible by giving a warning with a high warning level to the user using the object detection result. Further, the signal output from the object detection device is a radio wave of 10 GHz or more, and the same effect can be obtained even in a frequency band (24 GHz band or 77 GHz band) that can be used for object detection around the vehicle.

  The transmission / reception unit 11 illustrated in FIG. 2 may not include the band filters 116 and 121, the power amplifier 117, and the LNA 120. In addition, the antenna 119 can be configured separately for transmission and reception, and in that case, the antenna switch 118 is not necessary.

  Further, some timings in the vicinity of the reception timing may be stored, processed, and determined from the sampling timing. Furthermore, the determination of whether or not the reception timing in FIG. 4 has changed (S13) may also be determined with a predetermined width.

(Second Embodiment)
Next, an object detection apparatus according to the second embodiment of the present invention will be described. Note that the configuration of the object detection apparatus is the same as the block diagram described in the first embodiment with reference to FIGS. 1 and 2. In the object detection device according to the second embodiment, only the operations of the time change deriving unit 32 and the determining unit 33 are different. Therefore, the same components as those of the object detection device according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, the relationship between the transmission pulse signal P transmitted by the transmission / reception unit 11 according to the second embodiment and the reflected signal E received is the same as that in the first embodiment described with reference to FIG. Description is omitted.

  The time change deriving unit 32 according to the second embodiment performs time-frequency conversion on the data accumulated in the received signal storage unit 31 to acquire a component on the frequency axis. Then, the determination unit 33 analyzes the component intensity of a predetermined frequency or higher among the frequency components obtained by the time change deriving unit 32, and determines whether or not the object is a living organism based on the component intensity. The determination result is output to the display unit 4. The processing operation of the signal processing unit 2 according to the second embodiment using data I and Q will be described below with reference to FIG. FIG. 12 is a flowchart showing the processing operation of the signal processing unit 2.

  In FIG. 12, the distance measuring unit 21 of the signal processing unit 2 detects the reception timing of the reflected signal using the data I and Q (step S31). Then, the distance measuring unit 21 calculates the distance from the object based on the time difference Δt between the transmission pulse signal and the reception timing (step S32).

  On the other hand, the reception signal storage unit 31 of the identification unit 3 holds at least one of the data I and Q for a predetermined time for each reception timing detected by the distance measurement unit 21 in step S21. Specifically, the identification unit 3 determines whether or not the previous reception timing is the same as the reception timing detected in step S31 (step S33), and when the reception timing changes, the identification signal storage unit 31 is changed. Clear and start storing new data I or Q (step S34). On the other hand, when the reception timing does not change, the data I or Q is stored in the reception signal storage unit 31 (step S35). Since the data I and Q stored in the reception signal storage unit 31 are the same as the reflected signal amplitude transitions Aa and Ab described with reference to FIGS. 5 and 6, detailed description thereof is omitted.

  Next, the identification unit 3 determines whether or not any IQ data for a predetermined time is stored in the received signal storage unit 31 (step S36), and if the data for the predetermined time is not stored, Returning to step S31, the process is repeated. When stored for a predetermined time, the time change deriving unit 32 of the identifying unit 3 performs time-frequency conversion on the data accumulated in the received signal storage unit 31 to obtain a component on the frequency axis (step S37). ). FIGS. 13 and 14 are graphs showing examples of the respective intensities (distributions) for the frequency components acquired by the time change deriving unit 32, and FIG. 13 shows the frequency components Fa corresponding to the reflected signal amplitude transition Aa reflected by the non-living object. FIG. 14 shows a frequency component Fb corresponding to the reflected signal amplitude transition Ab reflected by a living thing.

  As shown in FIG. 13, when the object that reflects the transmission pulse signal is a non-living object such as a vehicle or a wall, the reflected signal amplitude transition Aa changes slowly, so that the frequency component Fa hardly shows a high frequency component, The low frequency component has a peak intensity. For example, the frequency component Fa shows almost zero intensity with respect to the frequency fh or higher. On the other hand, as shown in FIG. 14, in the case of a living organism such as a human body, the reflected signal amplitude transition Ab changes finely and greatly, so that the frequency component Fb has an intensity with a peak of a high frequency component. For example, the frequency component Fb has an intensity peak above the frequency fh.

  Next, the determination unit 33 of the identification unit 3 analyzes the component intensity of the frequency fh or higher among the frequency components obtained by the time change deriving unit 32, and determines whether the component intensity is greater than a predetermined value ( Step S38). If the component intensity is greater than the predetermined value, the determination unit 33 determines that the object is a living thing (step S39), and proceeds to the next step S41. On the other hand, when the component intensity is equal to or less than the predetermined value, the determination unit 33 determines that the object is an inanimate object (step S40), and proceeds to the next step S41.

  In step S41, the determination unit 33 outputs the object identification determination result in step S39 or S40 to the display unit 4. Then, the identification unit 3 clears the data stored in the reception signal storage unit 31 (step S42), and the determination unit 33 determines whether or not to continue object detection (step S43). When the object detection is continued, the determination unit 33 returns to step S31 and continues the process. When the object detection is ended, the determination unit 33 ends the process according to the flowchart.

  As in the first embodiment, the display unit 4 displays the distance from the object output from the distance measuring unit 21 and the object identification determination result output from the determination unit 33. Moreover, you may provide the warning control part 6 between the ranging part 21 and the judgment part 33, the display part 4, and the speaker 5 (refer FIG. 11). The warning control unit 6 is configured by a general computer system, and outputs warning data to the display unit 4 and the speaker 5 in accordance with respective processing results in the distance measurement unit 21 and the determination unit 33. For example, when the distance to the object calculated by the distance measuring unit 21 is equal to or less than a predetermined distance, the warning control unit 6 outputs warning data to the speaker 5 to warn the speaker 5 with voice or warn the display unit 4. The display unit 4 displays a warning by outputting the data. When the determination unit 33 identifies and determines that the object is a living body such as a human body and the distance to the object calculated by the distance measurement unit 21 is equal to or less than a predetermined distance, the warning control unit 6 displays the distance on the display unit 4. The warning data is output to the speaker 5 and the speaker 5 outputs a warning by voice, or the warning data is output to the display unit 4 and the display unit 4 displays the warning.

  As described above, according to the object detection device according to the second embodiment, by analyzing the frequency component of the reflected signal, not only the distance from the object existing around the object detection device but also the object is detected. It can be determined whether or not it is a living organism. Further, in the case of a living thing, a highly reliable warning is possible by giving a warning with a high warning level to the user using the object detection result. Further, the signal output from the object detection device is a radio wave of 10 GHz or more, and the same effect can be obtained even in a frequency band (24 GHz band or 77 GHz band) that can be used for object detection around the vehicle.

  A plurality of object detection devices according to the first and second embodiments can be installed to constitute a system. FIG. 15 is a block diagram illustrating a configuration of a system including a plurality of object detection devices 1a to 1n.

  In FIG. 15, the system includes n object detection devices 1 a to 1 n, a central control unit 10, a display unit 4, and a speaker 5. For example, when the system is installed in the vehicle for detecting an object around the vehicle, the n object detection devices 1a to 1n each transmit a transmission pulse signal in a specific direction toward the outside of the vehicle. Then, each of the object detection devices 1a to 1n receives the reflection signal, and outputs the distance to the object and the object identification determination result to the central control unit 10 as described above.

  The central control unit 10 is configured by a general computer system, and receives a distance from an object and an object identification determination result respectively output from the object detection devices 1a to 1n. Then, the central control unit 10 analyzes the presence of an object around the vehicle based on each output result, and outputs the result to the display unit 4 and the speaker 5. For example, the central control unit 10 displays the distance to the object and the object identification determination result output from each of the object detection devices 1a to 1n on the display unit 4. Further, when the object is approaching any of the object detection devices 1a to 1n, the central control unit 10 may warn with a voice through the speaker 5 or display a warning on the display unit 4. . Further, the central control unit 10 displays the distance or displays a warning or a warning display only when one of the object detection devices 1a to 1n can identify the object as a living body such as a human body. You can also By constructing such a system, it is possible to detect an object in a plurality of directions around the vehicle.

  In the above description, in order to use the object detection device for detecting objects around the vehicle, the example in which the object detection device is installed in the vehicle is used. However, the object detection device of the present invention can be used for other purposes. It is. For example, even when used in a vehicle, the air detection operation control at the time of a vehicle collision may be performed by the object detection device detecting an object inside the vehicle and identifying whether the object on the seat is a luggage or a person. It can also be used for purposes such as installing an object detection device outdoors or indoors, such as a house or building, to issue a warning only to an approaching organism or to give a warning to a user. . In addition, by installing an object detection device on home robots such as humanoids and pets, robots for disaster relief, and military portable devices, functions that allow the robot to react only when it detects a living thing, It is possible to add a function of detecting a living thing and its position in the dark.

  The object detection device, the object detection system, and the object detection method according to the present invention can not only detect the distance to an object existing around the object, but also determine whether the object is a living thing. It can also be used for purposes such as monitoring surroundings, detecting passengers in vehicle interiors, crime prevention inside and outside buildings, and adding biological identification functions to robots.

The block diagram which shows the structure of the object detection apparatus which concerns on the 1st and 2nd embodiment of this invention. FIG. 1 is a block diagram illustrating a configuration when the transmission / reception unit 11 in FIG. 1 transmits and receives signals using radio waves. The figure which shows roughly the relationship between the transmission pulse signal P and the reflected signal E by making a horizontal axis into time t. The flowchart which shows the processing operation of the signal processing part 2 which concerns on the 1st Embodiment of this invention. The graph which shows the reflected signal amplitude transition Aa reflected by the non-living thing stored in the received signal storage part 31 of FIG. The graph which shows the reflected signal amplitude transition Ab reflected by the living thing stored in the received signal storage part 31 of FIG. The graph which shows distribution of the difference value Da according to the reflected signal amplitude transition Aa reflected in the inanimate which the time change derivation part 32 of FIG. 1 analyzed The graph which shows distribution of difference value Db according to reflected signal amplitude transition Ab reflected by the living thing which time change deriving part 32 of Drawing 1 analyzed The graph which shows distribution of difference value Da which normalized the distribution of FIG. 7 with the average value The graph which shows distribution of difference value Db which normalized the distribution of FIG. 8 with the average value 1 is a block diagram showing a configuration in which a warning control unit 6 is added to the object detection device of FIG. The flowchart which shows the processing operation of the signal processing part 2 which concerns on the 2nd Embodiment of this invention. The graph which shows the frequency component Fa according to the reflected signal amplitude transition Aa reflected in the non-living object which the time change derivation | leading-out part 32 of FIG. 1 acquired The graph which shows the frequency component Fb according to the reflected signal amplitude transition Ab reflected by the living thing which the time change derivation part 32 of FIG. 1 acquired The block diagram which shows the structure of the system which has several object detection apparatus 1a-1n. Block diagram for explaining a conventional object classification method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Object detection apparatus 11 ... Transmission / reception part 111 ... Clock transmitter 112 ... Delay circuit 113 ... Pulse generator 114 ... Local oscillator 115 ... Mixer 116, 121 ... Band-pass filter 117 ... Power amplifier 118 ... Antenna switch 119 ... Antenna 120 ... LNA
122 ... IQ detector 123 ... A / D converter 2 ... Signal processing unit 21 ... Ranging unit 3 ... Identification unit 31 ... Received signal storage unit 32 ... Time change deriving unit 33 ... Judgment unit 4 ... Display unit 5 ... Speaker 6 ... Warning control unit 10 ... Centralized control unit

Claims (20)

An object detection device that identifies surrounding objects and calculates the distance to the object,
A transmission / reception unit that up-converts and transmits a transmission signal having a predetermined frequency, receives the reflected signal reflected by the object, and down-converts the transmission signal;
A distance measuring unit that calculates a distance to an object based on a time difference from when the transmission / reception unit transmits the transmission signal to when the reflection signal is received;
A storage unit that stores the reflected signal down-converted by the transmission / reception unit for a predetermined time at each timing of receiving the reflected signal;
A time change deriving unit that calculates a change distribution within the predetermined time with respect to the reflected signal stored in the storage unit;
An object detection apparatus comprising: a determination unit configured to determine that an object reflecting the reflection signal is a living organism based on the change distribution of the reflection signal calculated by the time change deriving unit. The time change deriving unit calculates a time-series difference value from the reflected signal stored in the storage unit for a predetermined time, calculates a distribution of the difference value,
The said determination part determines that the object which reflected the said reflected signal is a living body when the dispersion value of the distribution of the difference value calculated by the said time change derivation | leading-out part is larger than predetermined value. The object detection apparatus described in 1. The time change deriving unit performs frequency conversion according to time on the reflected signal stored in the storage unit for a predetermined time, and calculates the distribution of the frequency component,
The determination unit determines that the object reflecting the reflected signal is a living thing when the frequency component distribution calculated by the time change deriving unit includes a frequency component equal to or higher than a predetermined frequency. The object detection device according to claim 1.   The object detection apparatus according to claim 1, wherein a medium of a transmission signal transmitted by the transmission / reception unit is a radio wave of 10 GHz or more. The transmission / reception unit down-converts the in-phase component and the quadrature component of the reflected signal,
The storage unit stores at least one of the in-phase component and the quadrature component of the reflected signal down-converted by the transmission / reception unit for a predetermined time,
The said time change derivation | leading-out part calculates the change distribution in the said predetermined time with respect to at least one of the in-phase component of a reflected signal stored in the said storage part, and a quadrature component, It is characterized by the above-mentioned. Object detection device. An object detection system that identifies surrounding objects and calculates the distance to the object and outputs information according to each result,
At least one object detection device;
A control unit that controls information to be given to the user according to the identification of the object output from the object detection device and the distance to the object;
Based on information controlled by the control unit, an output unit for giving the information to the user,
The object detection device includes:
A transmission / reception unit that up-converts and transmits a transmission signal having a predetermined frequency, receives the reflected signal reflected by the object, and down-converts the transmission signal;
A distance measuring unit that calculates a distance to an object based on a time difference from when the transmission / reception unit transmits the transmission signal to when the reflection signal is received;
A storage unit that stores the reflected signal down-converted by the transmission / reception unit for a predetermined time at each timing of receiving the reflected signal;
A time change deriving unit that calculates a change distribution within the predetermined time with respect to the reflected signal stored in the storage unit;
A determination unit that determines, based on the change distribution of the reflected signal calculated by the time change deriving unit, that the object reflecting the reflected signal is a living thing,
The said control part outputs the information regarding the distance to the said object which the said ranging part calculated to the said output part, when the said judgment part judges an object to be a living body, The object detection system characterized by the above-mentioned.   The control unit outputs warning information to the user to the output unit when the determination unit determines that the object is a living thing and the distance to the object calculated by the ranging unit is equal to or less than a predetermined distance. The object detection system according to claim 6. The time change deriving unit calculates a time-series difference value from the reflected signal stored in the storage unit for a predetermined time, calculates a distribution of the difference value,
The said determination part determines that the object which reflected the said reflected signal is a living body, when the dispersion value of the distribution of the difference value calculated by the said time change derivation | leading-out part is larger than predetermined value, It is characterized by the above-mentioned. The object detection system described in 1. The time change deriving unit performs frequency conversion according to time on the reflected signal stored in the storage unit for a predetermined time, and calculates the distribution of the frequency component,
The determination unit determines that the object reflecting the reflected signal is a living thing when the frequency component distribution calculated by the time change deriving unit includes a frequency component equal to or higher than a predetermined frequency. The object detection system according to claim 6. A plurality of the object detection devices each sending the transmission signal in a unique direction;
The control unit, when at least one of the determination units included in the plurality of object detection devices determines that the object is a living thing, information on the distance to the object calculated by the distance measurement unit included in the object detection device Is output to the output unit. The object detection system according to claim 6. A plurality of the object detection devices each sending the transmission signal in a unique direction;
The control unit determines that at least one of the determination units included in the plurality of object detection devices determines that the object is a living thing, and a distance to the object calculated by the distance measurement unit included in the object detection device is predetermined. The object detection system according to claim 6, wherein warning information for a user is output to the output unit when the distance is equal to or less than the distance. An object detection method for identifying a surrounding object and calculating a distance to the object,
A transmission / reception step of up-converting and transmitting a transmission signal having a predetermined frequency, receiving the reflected signal reflected by the object and down-converting the transmission signal;
A distance measuring step for calculating a distance to an object based on a time difference between sending the transmission signal and receiving the reflected signal in the transmission / reception step;
A storage step of storing the reflected signal down-converted in the transmission / reception step for a predetermined time at each reception timing of the reflected signal;
A time change deriving step of calculating a change distribution within the predetermined time with respect to the reflected signal stored in the storing step;
A determination step of determining, based on the change distribution of the reflection signal calculated in the time change derivation step, that the object reflecting the reflection signal is a living thing. The time change derivation step calculates a time-series difference value from the reflection signal stored for a predetermined time in the storage step, calculates a distribution of the difference value,
13. The determination step according to claim 12, wherein when the variance value of the distribution of difference values calculated by the time change deriving step is larger than a predetermined value, it is determined that the object reflecting the reflection signal is a living thing. The object detection method described in 1. The time change derivation step performs frequency conversion according to time on the reflected signal stored for a predetermined time in the storage step, and calculates the distribution of the frequency component,
The determining step determines that the object reflecting the reflected signal is a living thing when the frequency component distribution calculated in the time change deriving step includes a frequency component equal to or higher than a predetermined frequency. The object detection method according to claim 12.   The object detection method according to claim 12, wherein a medium of a transmission signal transmitted in the transmission / reception step is a radio wave of 10 GHz or more. The transmitting / receiving step down-converts the in-phase component and the quadrature component of the reflected signal,
The storing step stores at least one of the in-phase component and the quadrature component of the reflected signal down-converted in the transmission / reception step for a predetermined time,
The time change deriving step calculates a change distribution within the predetermined time for at least one of an in-phase component and a quadrature component of the reflected signal stored in the storing step. Object detection method.   The information processing step further includes: an information control step of giving information regarding a distance to the object calculated by the distance measuring step to the user when the determining step determines that the object reflecting the reflected signal is a living thing. 12. The object detection method according to 12.   The information control step is characterized in that when the determination step determines that the object is a living thing and the distance to the object calculated by the distance measurement step is equal to or less than a predetermined distance, warning information is given to the user. The object detection method according to claim 17. The determining step determines that each reflected object is a living organism based on the reflected signal received by the transmitting / receiving step that transmits the transmission signal in a unique direction.
18. The information control step according to claim 17, wherein when the determination step determines that at least one object is a living thing, the information control step gives the user information regarding the distance to the object calculated by the distance measurement step. Object detection method. The determining step determines that each reflected object is a living organism based on the reflected signal received by the transmitting / receiving step that transmits the transmission signal in a unique direction.
In the information control step, at least one object is determined as a living thing in the determination step, and warning information is given to the user when the distance to the object calculated in the distance measurement step is equal to or less than a predetermined distance. The object detection method according to claim 17.

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