JP2013072865A - Detection device, detection method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device, a detection method and a program capable of improving detection accuracy of motion of an object.SOLUTION: A detection device includes a motion detection part in which, based on a beat signal having, as a frequency, the frequency difference between a transmission signal whose frequency changes in a constant sweeping section and a receiving signal received in accordance with transmission of the transmission signal, the phase shift amount of the beat signal is calculated for every sweeping section, and, based on the calculated phase shift amount, the motion of an object is detected.

Description

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

  A technique for detecting the movement of an object in a non-contact manner by using a Doppler sensor has been developed. As a technique for detecting a heartbeat of a human body by using two types of sensors, a radio wave type Doppler sensor and a low-frequency sensor arranged close to the human body (target object), for example, Patent Document 1 Can be mentioned. Moreover, as a technique for detecting the occupant's heartbeat using a Doppler sensor provided in the vehicle, for example, Patent Document 2 is cited.

JP 2006-0555504 A JP 2010-142456 A

  For example, the techniques described in Patent Document 1 and Patent Document 2 for detecting the movement of an object in a non-contact manner (hereinafter sometimes collectively referred to as “conventional technology”) are frequency shifts caused by the Doppler effect. The motion of the object is detected based on the beat signal that can be detected by. Therefore, there is a possibility that the movement of the object can be detected in a non-contact manner by using the conventional technique.

  However, in the case of detecting the movement of an object based on a beat signal that can be detected by a frequency shift due to the Doppler effect, if the object to be detected does not move to some extent, the signal to noise ratio (Signal to Noise ratio) Becomes worse. Therefore, when the conventional technique is used, it is not always possible to accurately detect the movement of the object.

  Further, for example, the conventional technique disclosed in Patent Document 1 uses two types of sensors, a Doppler sensor and a low-frequency sensor, and the low-frequency sensor must be disposed close to a human body (target object). Further, for example, the conventional technique shown in Patent Document 2 specifies the heartbeat position based on the signal itself of the Doppler sensor or the amplitude of the frequency band component likely to be related to the heartbeat (movement of the detection target). If the target object is not close, it is difficult to detect the movement of the object. Therefore, for example, when the conventional techniques shown in Patent Document 1 and Patent Document 2 are used, there is a risk that an environment for detecting the motion of an object may be restricted.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved detection apparatus, detection method, and method capable of improving the detection accuracy of an object motion. And to provide a program.

  In order to solve the above-described problem, according to the first aspect of the present invention, a frequency difference between a transmission signal whose frequency changes in a certain sweep interval and a reception signal received in response to transmission of the transmission signal is calculated. A detection apparatus comprising a motion detection unit that calculates a phase shift amount of the beat signal for each sweep section based on a beat signal having a frequency and detects a motion of an object based on the calculated phase shift amount Is provided.

  With this configuration, it is possible to improve the detection accuracy of the movement of the object.

  The apparatus further includes a detection unit that transmits the transmission signal and outputs the beat signal based on the transmission signal and the reception signal. The motion detection unit is configured to output the beat signal output from the detection unit. The phase shift amount may be calculated.

  In addition, a frequency conversion unit that converts the frequency of the beat signal for each sweep section is further provided, and the motion detection unit calculates a phase shift amount of the beat signal for each frequency in the beat signal subjected to frequency conversion. May be.

  The motion detection unit may detect the motion of the object based on the variation in the phase shift amount calculated for each frequency.

  In addition, the motion detection unit generates time-series data of the phase shift amount for each frequency, and is calculated based on the time-series data for each frequency, and temporal changes in the phase shift amount of the beat signal for each frequency The movement of the object may be detected based on the component.

  In addition, the motion detection unit generates time-series data of the phase shift amount, and based on the temporal change component of the phase shift amount of the beat signal calculated based on the time-series data, the motion detection unit It may be detected.

  Further, the motion detection unit may calculate a feature value indicating a feature of motion change in space based on the temporal change component of the phase shift amount.

  The feature value may indicate at least one of speed, acceleration, and jerk components.

  The motion detection unit may detect the motion of the object based on the variation in the phase shift amount.

  The motion detection unit may further detect the motion of the object based on the amplitude of each frequency component in the beat signal.

  In order to achieve the above object, according to the second aspect of the present invention, the frequency of a transmission signal whose frequency changes in a certain sweep interval and a reception signal received in response to transmission of the transmission signal A detection method comprising: calculating a phase shift amount of the beat signal for each sweep section based on a beat signal having a difference as a frequency; and detecting a motion of an object based on the calculated phase shift amount Is provided.

  By using such a method, it is possible to improve the detection accuracy of the movement of the object.

  The method further includes the step of transmitting the transmission signal and outputting the beat signal based on the transmission signal and the reception signal, and the step of detecting the movement of the object includes the step of outputting the beat signal. The phase shift amount of the beat signal output in step S1 may be calculated.

  In addition, the method further includes the step of frequency-converting the beat signal for each sweep section, and in the step of detecting the motion of the object, the phase shift amount of the beat signal for each frequency in the beat signal subjected to frequency conversion May be calculated.

  In addition, the method further includes the step of transmitting the transmission signal and outputting the beat signal based on the transmission signal and the reception signal. In the step of converting the frequency, the beat signal is output in the step of outputting the beat signal. The beat signal may be frequency converted.

  In order to achieve the above object, according to the second aspect of the present invention, the frequency of a transmission signal whose frequency changes in a certain sweep interval and a reception signal received in response to transmission of the transmission signal Based on the beat signal having the difference as a frequency, the phase shift amount of the beat signal is calculated for each sweep section, and the computer functions as a means for detecting the motion of the object based on the calculated phase shift amount. A program is provided.

  By using such a program, it is possible to improve the detection accuracy of the movement of the object.

  According to the present invention, it is possible to improve the detection accuracy of an object motion.

It is explanatory drawing which shows an example of a structure of the detection apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows an example of the transmission signal which the detection apparatus which concerns on 1st Embodiment transmits. It is explanatory drawing which shows an example of the frequency difference of the transmission signal and reception signal which concern on embodiment of this invention. It is explanatory drawing which shows an example of a structure of the detection apparatus which concerns on the 2nd Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Detection method according to an embodiment of the present invention)
Before describing the configuration of the detection apparatus according to the embodiment of the present invention, the detection method according to the embodiment of the present invention will be described. In the following, the processing related to the detection method according to the embodiment of the present invention will be described as being performed by the detection apparatus according to the embodiment of the present invention.

  As described above, when the movement of an object is detected based on a beat signal that can be detected by a frequency shift due to the Doppler effect, the movement of the object is not always accurately detected.

  Therefore, the detection apparatus according to the embodiment of the present invention transmits a transmission signal whose frequency is swept, and information on the phase of the beat signal based on the transmission signal and a reception signal received in response to transmission of the transmission signal. Based on this, the movement of the object is detected. Here, the beat signal according to the embodiment of the present invention is a signal having a frequency difference between a transmission signal and a reception signal as a frequency. In addition, examples of the motion of the object detected by the detection apparatus according to the embodiment of the present invention include the presence / absence of the motion of the object and the content of the motion specified (or estimated) by the motion detection.

  More specifically, the detection apparatus according to the embodiment of the present invention performs, for example, the following processing (1) (detection processing) to (3) (motion detection processing) to detect the motion of the object. To detect.

(1) Detection Processing The detection apparatus according to the embodiment of the present invention transmits a transmission signal whose frequency changes in a certain sweep section. And the detection apparatus which concerns on embodiment of this invention acquires a beat signal based on the transmission signal and the received signal received according to transmission of a transmission signal.

  More specifically, the detection apparatus according to the embodiment of the present invention includes, for example, a Doppler sensor, and repeatedly transmits a transmission signal whose frequency changes in a certain sweep section. Then, the detection device according to the embodiment of the present invention interferes the transmission signal and the reception signal, and obtains a beat signal having a frequency difference between the transmission signal and the reception signal as a frequency.

  Here, as the transmission signal according to the embodiment of the present invention, for example, a signal transmitted by an electromagnetic wave such as a microwave (10 [GHz] or 24 [GHz]) or a millimeter wave, or a sound wave such as an ultrasonic wave is used. A signal to be transmitted and a signal transmitted by light are exemplified. In addition, the received signal according to the embodiment of the present invention is a signal obtained by reflecting a transmitted signal transmitted by a medium or an object.

  The Doppler sensor can be broadly divided into a CW (Continuous Wave) type that transmits an unmodulated wave with a constant frequency and an FMCW (Frequency Modulated Continuous Wave) type that changes the frequency of a signal to be transmitted at a constant time interval. Can be mentioned. The beat signal obtained by the CW-type Doppler sensor mainly includes a frequency shift due to the Doppler effect that causes a frequency change proportional to the speed of reflection by an object or the like. Therefore, when a CW-type Doppler sensor is used, it is not always possible to detect the movement of an object with high accuracy. Therefore, the detection apparatus according to the embodiment of the present invention uses, for example, an FMCW type Doppler sensor in order to transmit a transmission signal for sweeping the frequency. Note that the FMCW type Doppler sensor according to the embodiment of the present invention may be any sensor that can transmit a carrier wave that can cause a Doppler effect by being reflected by an object.

Here, examples of the frequency sweep include an upward sweep and a downward sweep. When the lower limit frequency is set to “f ₀ ” and the upper limit frequency is set to “f ₀ + B”, for example, the upward sweep is a transmission signal of the lower limit frequency f ₀ is transmitted at time ts (s), and time ts (s) + T _B (s) means increasing the frequency at a constant pace so as to reach the upper limit frequency f ₀ + B. Further, the downward sweep is, for example, at a constant pace so that a transmission signal of the upper limit frequency f ₀ + B is transmitted at time ts (s) and reaches the lower limit frequency f ₀ at time ts (s) + T _B (s). This means lowering the frequency. Hereinafter, the period corresponding to the period T _B (s) from the time ts (s) to the time ts (s) + T _B (s) related to the frequency sweep as described above is referred to as a “sweep section”. .

  Further, examples of the frequency sweep include a sawtooth sweep in which only an upward sweep is performed, and a triangular sweep in which an upward sweep and a downward sweep are repeated.

  The detection apparatus according to the embodiment of the present invention includes, for example, an FMCW type Doppler sensor to transmit a transmission signal whose frequency changes in a certain sweep section, and obtains a beat signal based on the transmission signal and the reception signal . A specific example of the detection process in the detection apparatus according to the embodiment of the present invention will be described later.

  Note that the detection device according to the embodiment of the present invention receives, for example, a beat signal output from an external detection device including an FMCW type Doppler sensor connected via a network (or directly). For example, when a beat signal is acquired from an external device, the process (1) (detection process) may not be performed. In the above case, the detection apparatus according to the embodiment of the present invention performs the process (2) (frequency conversion process) and the process (3) (motion detection) described later based on the beat signal acquired from the external apparatus. Processing) or processing (3) described later (motion detection processing) is performed.

  Here, as the network according to the embodiment of the present invention, for example, a wired network such as a LAN (Local Area Network), a wireless LAN (WLAN; Wireless Local Area Network), or a wireless WAN (WWAN; Wireless Wide Area) via a base station is used. Examples include a wireless network such as an area network or the Internet using a communication protocol such as TCP / IP (Transmission Control Protocol / Internet Protocol).

(2) Frequency conversion process The detection device according to the embodiment of the present invention frequency-converts the beat signal acquired in the process (1) (detection process) for each sweep section. Here, as a frequency conversion method according to the embodiment of the present invention, for example, a method using Fourier transform, a method using discrete cosine transform, a method using wavelet transform, a method using Wigner transform, and a method using Hadamard transform And a method using the Matching Pursuit method. The frequency conversion method according to the embodiment of the present invention is not limited to the above. For example, the detection apparatus according to the embodiment of the present invention can use any method capable of time / frequency conversion.

  By performing frequency conversion of the beat signal and performing processing (motion detection processing) described later (3), the detection device according to the embodiment of the present invention is, for example, a distance from the detection device according to the embodiment of the present invention. Can detect motion in different objects. A specific example of the frequency conversion process in the detection apparatus according to the embodiment of the present invention will be described later.

  Note that the detection apparatus according to the embodiment of the present invention can perform the process (3) (motion detection process) described later without performing the process (2) (frequency conversion process). When the process (3) described later is performed without performing the process (2), the detection apparatus according to the embodiment of the present invention has a single distance from the detection apparatus according to the embodiment of the present invention. The movement in the object will be detected.

(3) Motion Detection Processing The detection apparatus according to the embodiment of the present invention calculates the phase shift amount of the beat signal for each sweep section, and detects the motion of the object based on the calculated phase shift amount. When performing the process (2) (frequency conversion process), the detection apparatus according to the embodiment of the present invention calculates the phase shift amount of the beat signal for each frequency in the beat signal subjected to the frequency conversion. .

  Here, the phase shift amount of the beat signal according to the embodiment of the present invention is, for example, the amount of change in phase in temporally adjacent sweep sections. The detection apparatus according to the embodiment of the present invention detects the movement of an object by capturing a temporal change in the phase shift amount of the beat signal as a movement component of the object in space.

  As described above, the detection apparatus according to the embodiment of the present invention detects the movement of the object by detecting the temporal change in the phase shift amount of the beat signal as the movement component of the object in space. It is also possible to detect movement.

  In addition, the detection apparatus according to the embodiment of the present invention approximates the relationship between the phase shift amount of the beat signal and the distance between the detection apparatus according to the embodiment of the present invention and the object in space. You may calculate the feature value which shows the characteristic of the change of a motion. Here, examples of the feature value indicating the feature of the change in motion on the space according to the embodiment of the present invention include speed, acceleration, and jerk components. By calculating the feature value indicating the feature of the change of the motion in the space as described above, the detection device according to the embodiment of the present invention can further respirate a person (an example of an object that detects motion), a heartbeat, and the like. It can be easily detected.

  A specific example of the motion detection process in the detection apparatus according to the embodiment of the present invention will be described later.

  The detection apparatus according to the embodiment of the present invention includes, for example, the process (1) (detection process) to the process (3) (motion detection process) as the process related to the detection method according to the embodiment of the present invention. The process (2) (frequency conversion process) and the process (3) (motion detection process), the process (1) (detection process) and the process (3) (motion detection process), or The process (3) (motion detection process) is performed.

  Here, the detection apparatus according to the embodiment of the present invention obtains a beat signal by the process (1) (detection process) or from an external apparatus, and in the process (3), the phase of the beat signal is acquired. The movement of the object is detected by regarding the temporal change of the shift amount as the movement component of the object in space. Here, when the temporal change in the phase shift amount of the beat signal is regarded as the motion component of the object in space, the signal-to-noise ratio of the signal may deteriorate even if the object to be detected moves finely. Can be reduced more than when conventional techniques are used.

  Therefore, the detection apparatus according to the embodiment of the present invention can improve the detection accuracy of the motion of the object by performing the processing according to the detection method according to the embodiment of the present invention.

  Hereinafter, an example of the configuration of the detection device according to the embodiment of the present invention will be described, and a specific example of processing according to the detection method according to the embodiment of the present invention will also be described.

(Detecting device according to the first embodiment)
FIG. 1 is an explanatory diagram showing an example of the configuration of the detection apparatus 100 according to the first embodiment of the present invention. The detection apparatus 100 includes, for example, a detection unit 102, a frequency conversion unit 104, and a motion detection unit 106.

  In addition, the detection apparatus 100 includes, for example, a control unit (not shown), a ROM (Read Only Memory, not shown), a RAM (Random Access Memory, not shown), a storage unit (not shown), and a user. An operable operation unit (not shown), a display unit (not shown) for displaying various screens on a display screen, a communication unit (not shown) for communicating with an external device, and the like may be provided. . The detection apparatus 100 connects the above-described constituent elements by, for example, a bus as a data transmission path.

  Here, the control unit (not shown) includes, for example, an MPU (Micro Processing Unit) and an integrated circuit for realizing various functions, and serves to control the entire detection apparatus 100. In addition, the control unit (not shown) may serve to perform a part of processing related to the detection method according to the embodiment of the present invention, such as the frequency conversion unit 104 and the motion detection unit 106, for example. Note that the detection apparatus 100 includes the frequency conversion unit 104 and the motion detection unit 106 as processing circuits (individual processing circuits or common processing circuits) separate from the control unit (not shown). Needless to say, what you can do.

  The ROM (not shown) stores control data such as programs and calculation parameters used by a control unit (not shown), for example. A RAM (not shown) temporarily stores, for example, a program executed by a control unit (not shown).

  The storage unit (not shown) is a storage unit included in the detection device 100, and stores various data such as data indicating the detection result of the motion detected by the motion detection unit 106 and applications. Here, examples of the storage unit (not shown) include a magnetic recording medium such as a hard disk, and a nonvolatile memory such as a flash memory. Further, the storage unit (not shown) may be detachable from the detection device 100.

  Examples of the operation unit (not shown) include a button, a direction key, or a combination thereof. The detection device 100 can also be connected to an operation device as an external device of the detection device 100 such as a keyboard and a mouse.

  As a display part (not shown), a liquid crystal display (Liquid Crystal Display), an organic EL display (organic ElectroLuminescence display), etc. are mentioned, for example. The display unit (not shown) may be a device capable of display and user operation, such as a touch screen. In addition, the detection apparatus 100 can be connected to a display device (for example, an external display) as an external apparatus of the detection apparatus 100 regardless of the presence or absence of a display unit (not shown).

  The detection unit 102 plays a role of performing the process (1) (detection process), transmits a transmission signal whose frequency changes in a certain sweep section, and outputs a beat signal based on the transmission signal and the reception signal. To do. The detection unit 102 includes, for example, an FMCW type Doppler sensor.

FIG. 2 is an explanatory diagram illustrating an example of a transmission signal transmitted by the detection apparatus 100 according to the first embodiment. Here, in FIG. 2, when the detection unit 102 sweeps the frequency in a triangular wave shape, an example of a frequency change ((B) shown in FIG. 2) and an example of a waveform of a transmission signal (A shown in FIG. 2) )). In addition, “f ₀ ” illustrated in FIG. 2 indicates a lower limit frequency, and “f ₀ + B” illustrated in FIG. 2 indicates an upper limit frequency. Then, T _B (s) shown in FIG. 2 indicates a sweep section.

  Here, as shown in FIG. 2, the advantage of sweeping the frequency in a triangular wave shape is that, generally, after a transmission signal is transmitted, the transmission signal hits a reflector such as an object and is reflected as a reception signal. The round-trip propagation delay time until reception is obtained in a relationship proportional to the frequency difference between the transmission signal and the reception signal. That is, the detection unit 102 sweeps the frequency in a triangular wave shape and transmits a transmission signal, so that the distance between the object and the detection device 100 (more precisely, the distance between the object and the detection unit 102) becomes the beat signal. Is obtained as a frequency.

  In general, the reflector exists at a plurality of distances when viewed from the detection unit 102. For example, when viewed from the detection unit 102 indoors, various reflectors such as walls, floors, furniture, people, and animals may exist. Therefore, the detection unit 102 receives a signal obtained by combining the transmission signals reflected by the plurality of reflectors as described above as a reception signal. For example, the detection unit 102 extracts and uses the frequency component having the largest amplitude among the received signals, or uses the received signal by separating the frequency components by distance by performing frequency conversion.

  Note that the frequency sweep in the detection unit 102 is not limited to a triangular wave sweep as shown in FIG. For example, the detection unit 102 may sweep the frequency by a one-side sweep of only an up sweep or a down sweep, like a saw-like sweep. The detection unit 102 is not limited to a triangular wave sweep or a sawtooth sweep, and can sweep an arbitrary pattern as long as a sweep section in which the frequency changes at a constant pace is repeated.

  Here, the detection unit 102 changes the transmission frequency by, for example, changing the voltage input to a VCO (voltage controlled oscillator) over time. Needless to say, the method of realizing the frequency sweep in the detection unit 102 is not limited to the above.

  Hereinafter, the process in the detection part 102 is demonstrated more concretely.

The detection unit 102 transmits, for example, a transmission signal v _s (t) expressed by the following Equation 1 at a time t when the sweep start time is 0 (zero). Here, “A _s ” shown in Equation 1 indicates the amplitude of the transmission signal, and “φ _s ” shown in Equation 1 is expressed by Equation 2 below, for example. Further, “f ₀ ” shown in Formula 2 indicates the sweep lower limit frequency [Hz], and “O _s ” shown in Formula 2 indicates the phase of the transmission signal at the start of sweep. Further, “T _B ” shown in Expression 2 indicates a sweep section, and “B” shown in Expression 2 indicates a sweep frequency [Hz].

・・・（数式１）

・・・（数式２）

... (Formula 1)

... (Formula 2)

Further, the transmission frequency ω _s [rad / s] of the transmission signal v _s (t) is expressed by, for example, Equation 3 below.

・・・（数式３）

... (Formula 3)

In general, the frequency of the carrier wave, from the very high relative to the repetition period of the sweep, it is difficult to synchronize the phase O _S at the beginning sweep carrier. For example, in the case of a microwave of 24 [GHz], since the repetition cycle of the sweep is about 1 [kHz] with respect to the frequency of 24 [GHz] of the carrier wave, it is synchronized with the carrier wave for controlling the repetition cycle of the sweep. Often, such control is not performed. Generally, the phase O _S at the beginning sweep is a value that changes every sweep. Therefore, the detection unit 102 transmits, for example, as a value that changes every sweep phase O _S at the beginning sweep the transmitted signal v _s a _(t).

Further, the received signal v _r (t) received in response to the transmission of the transmission signal v _s (t) is expressed by, for example, Equation 4 below. Here, “A _r ” shown in Equation 4 represents the amplitude of the received signal. Further, “φ _r ” shown in Expression 4 is expressed by Expression 5 below, for example. Here, “T _r ” shown in Expression 5 represents a delay time until the transmission signal is reflected by an object or the like and received as a reception signal.

・・・（数式４）

・・・（数式５）

... (Formula 4)

... (Formula 5)

Further, the reception frequency ω _r [rad / s] of the reception signal v _r (t) is expressed by, for example, the following Equation 6.

・・・（数式６）

... (Formula 6)

Detection unit 102 performs IQ detection on received frequency omega _r shown in equation 6, obtained, for example, Equation 7 below, the signal shown in Equation 8.

・・・（数式７）

・・・（数式８）

... (Formula 7)

... (Formula 8)

Here, the _{"cos (φ r + φ s} )" components shown in Equation 7, the _{"sin (φ r + φ s} )" components shown in Equation 8, for example, can be removed by a filter such as a low-pass filter . Therefore, the detection unit 102 acquires, for example, beat signals represented by the following formulas 9 and 10 based on the transmission signal v _s (t) and the reception signal v _r (t).

・・・（数式９）

・・・（数式１０）

... (Formula 9)

(Equation 10)

“A _b ” shown in Equation 9 and Equation 10 is expressed by the following Equation 11, for example, and “φ _b ” shown in Equation 9 and Equation 10 is expressed by the following Equation 12, for example. .

・・・（数式１１）

・・・（数式１２）

... (Formula 11)

... (Formula 12)

Further, the frequency ω _b [rad / s] of the beat signal is expressed by, for example, Expression 13 below.

・・・（数式１３）

... (Formula 13)

  The detection unit 102 acquires a beat signal, for example, by performing the calculations shown in Equation 9 and Equation 10. Then, the detection unit 102 outputs the beat signal to the frequency conversion unit 104.

  The beat signal output from the detection unit 102 is a signal having a frequency difference between the transmission signal and the reception signal as a frequency. FIG. 3 is an explanatory diagram illustrating an example of a frequency difference between the transmission signal and the reception signal according to the embodiment of the present invention. 3A shows an example of a transmission signal and a reception signal, and FIG. 3B shows a frequency difference between the transmission signal and the reception signal shown in FIG. . The detection unit 102 outputs a beat signal having a frequency difference as shown in FIG. 3B, for example, by performing the calculations shown in Equation 9 and Equation 10, for example.

[Significance of detecting motion of an object based on a phase shift amount of a beat signal according to an embodiment of the present invention]
Here, before describing the frequency converter 104 and the motion detector 106, the significance of detecting the motion of an object based on the phase shift amount of the beat signal according to the embodiment of the present invention will be described.

Detection device 100 (more precisely, the motion detection unit 106 to be described later), for example by performing the calculation shown in Equation 14 below, for the sweep interval, calculates a phase shift amount O _b of the beat signal.

・・・（数式１４）

... (Formula 14)

As shown in Formula 14, the phase shift amount O _b of the beat signal is not affected by the phase O _s of the transmission signal at the start of the sweep. Further, as shown in Equation 14, the beat signal phase shift amount O _b is equal to the distance between the detection device 100 and the object (when the sweep frequency B, the sweep interval T _B , and the lower limit frequency f ₀ are constant) ( More precisely, it is uniquely determined with respect to the delay time _Tr depending on the distance between the detection unit 102 and the object. Therefore, the phase shift amount O _b of the beat signal is calculated by the equation 14, a distance between the detection device 100 object uniquely determined by the sweep time t.

Also, the amplitude A _b of the beat signal, the transmitted signal v when the amplitude A _s of _{s (t)} is constant, which depends on the area and the reflection characteristic of the reflector, such as the object, the received signal v _{r (t)} determined by the amplitude _{a r.}

Here, when detecting a moving body in a specific space or detecting a change in a stationary body, for example, a change in the delay time T _r and the amplitude A _r of the received signal v _r (t) may be detected. However, the change in the delay time T _r affects the frequency ω _b of the beat signal and the phase shift amount O _b of the beat signal, as shown in Equation 13 and Equation 14. The amplitude A _r of the received signal v _{r (t),} so is dependent on the area and the reflection characteristic of the reflector as described above, by detecting the change in the amplitude A _r of the received signal v _{r (t)} When detecting the movement of an object, it is not always possible to improve the detection accuracy of the movement of the object.

Therefore, the detection device 100 corresponds to the time the carrier reciprocates between the detecting device 100 and the object, rather than the amplitude _{A r} of the delay time _{T r} and the received signal _v r (t), from the detection device 100 of the target A distance L [m] to the object is used. Assuming that the speed of the carrier wave carrying the transmission signal and the reception signal is “c” [m / s], for example, Equation 13 is expressed by Equation 15 below, and Equation 14 is expressed by Equation 16 below. expressed.

・・・（数式１５）

・・・（数式１６）

... (Formula 15)

... (Formula 16)

Here, frequency change due to frequency conversion using Discrete Fourier Transform (DFT) of the beat signal is considered. Beat signal is discontinuous before and after the sweep interval, the relational expression shown in the equation 1 above equation 16 is satisfied, in general, limited to sweep interval T in _B (more precisely, further considering the effects of round-trip of the transmission signal, it is shorter than the sweep period _{T B.).} That, considering the discrete Fourier transform in only the sweep interval T _B, the frequency resolution is limited to an integral multiple of 1 / T B _[Hz], which can be one wavelength expressed sweep interval T _B. The distance resolution “L _R ” [m] in the above case is expressed by the following Expression 17 from Expression 15, for example.

・・・（数式１７）

... (Formula 17)

When the carrier wave is a microwave, for example, c = 3.0 × 10 ⁸ [m / s], and when the transmission frequency B is 200 [MHz], the distance resolution _LR is 0.75 [ m].

  Here, for example, when the distance changes by 5 [cm] due to the movement of the object, the change in frequency becomes 6.6 [%]. When detecting the movement of an object by changing the frequency, for example, the movement of an object moving in the metric order such as a vehicle moving in a road or a warehouse can be easily detected because the movement is large. It is difficult to detect a centimeter order movement such as the above 5 cm movement. That is, when detecting the movement of an object based on a change in frequency, for example, it is not always possible to detect a load in a warehouse or the movement of a person.

On the other hand, paying attention to the phase shift amount O _b of the beat signal, (depending on the distance traveled by the object) varies as 0.5 cycles by the movement of the object. Therefore, it is preferable to use a change in the phase shift amount O _b of the beat signal, than when using a change in frequency, it is possible to detect the movement of the more easily the object.

Further, as in the case where the detection unit 102 uses a microwave of 24 [GHz] as a carrier wave and transmits a transmission signal at a sweep frequency / time of 200 [MHz] · 1 [ms], for example, term and if the order of the second term is significantly different, for example, as shown in equation 18 below, the phase shift amount O _b of the beat signal, so as to have a distance and linear relationship between the detection device 100 and the object Can be approximated. Here, “α” shown in Expression 18 is expressed by Expression 19 below.

・・・（数式１８）

・・・（数式１９）

... (Formula 18)

(Equation 19)

  Therefore, the detection apparatus 100 calculates the phase shift amount of the beat signal for each repetition period of the sweep, and detects the object using the temporal change component of the phase shift amount of the beat signal, thereby detecting the object in the space. It is possible to improve the motion detection accuracy.

  In the above description, the case where the detection apparatus 100 detects the movement of one reflector has been described as an example. However, the processing in the detection apparatus 100 according to the first embodiment of the present invention is not limited to the above. . As described above, various reflectors such as various objects and structures may exist in an actual space, and the detection device 100 is a distance between the detection device 100 and each reflector. Alternatively, a signal obtained by combining transmission signals reflected by reflectors having different reflection amounts or the like at the reflector can be received as a reception signal. Therefore, the detection apparatus 100 according to the first embodiment of the present invention may perform frequency analysis using, for example, Fourier transform or wavelet transform. By performing the frequency analysis, the detection apparatus 100 according to the first embodiment of the present invention can separate the influence for each distance in the range of the frequency resolution, for example.

  With reference to FIG. 1 again, an example of the configuration of the detection apparatus 100 according to the first embodiment of the present invention will be described. The frequency conversion unit 104 plays a leading role in performing the process (2) (frequency conversion process), and frequency-converts the beat signal output from the detection unit 102 for each sweep section.

  Hereinafter, the processing in the frequency conversion unit 104 will be described by taking as an example a case where the frequency conversion unit 104 performs frequency conversion of the beat signal using Fourier transform. Note that the frequency conversion processing in the frequency conversion unit 104 according to the first embodiment of the present invention is not limited to the above. For example, the frequency conversion unit 104 may perform frequency conversion on the beat signal using wavelet conversion, Wigner conversion, Matching Pursuit method, or the like.

In the following, the processing in the frequency conversion unit 104 will be described by taking as an example a case where the detection unit 102 performs sweeping by the sweep section T _B (s) N times (N is a positive integer).

For example, as shown in FIG. 2B, when sweeping between the lower limit and the upper limit of the frequency, it is necessary to return the frequency to the initial value before the sweep in order to perform the sweep again, and the frequency is returned to the initial value. May require a finite time, ie, a sweep preparation period. Assuming that the sweep preparation period is “T _p (s)”, the period T _T (S) required for one sweep process is the combined period of the sweep section and the sweep preparation period, that is, (T _B + T _P ). (S). Ideally, T _p (s) = 0, but considering the stability of the VCO used to change the transmission frequency, for example, in reality, T _p (s) = 0. It is difficult to do. Further, when reverse sweep is performed, T _B (s) = T _p (s) may be obtained when viewed from one side sweep.

Here, the sampling frequency is set to “f _s ” [Hz], and the discrete Fourier transform in the (i + 1) -th (i = 0, 1,..., N−1) sweep process is considered. When the sweep start time t = 0 [s], the frequency conversion unit 104 falls under the sweep end time from time t = T _S (s), for example, because it is not affected by the transmission signal before the sweep start. Fourier transform is performed on the interval up to time T _B (s).

  The frequency conversion unit 104 performs one discrete Fourier transform for one sweep, but the processing in the frequency conversion unit 104 according to the first embodiment of the present invention is not limited to the above. For example, the frequency conversion unit 104 according to the first embodiment of the present invention may divide the sweep section into a plurality of sections and perform a discrete Fourier transform for each of the divided sections, or a window of a certain size. A plurality of sections may be extracted by sliding and the discrete Fourier transform may be performed for each extracted section. Hereinafter, a case where the frequency conversion unit 104 performs one discrete Fourier transform for one sweep will be described as an example.

The frequency conversion unit 104 samples the beat signals shown in Equation 9 and Equation 10, that is, the Doppler I _L component and Q _L component at the sampling frequency f _s [Hz], and sets them as a real part and an imaginary part, respectively. A complex number sequence Xi = (x _{0, i} , x _{1, i} ,..., X _{M−1, i} ) is constructed. Here, the number M of elements of the complex number sequence Xi is expressed by, for example, Equation 20 below.

・・・（数式２０）

(Equation 20)

If the complex number sequence after the discrete Fourier transform is “Ci = (c _{0, i} , c _{1, i} ,..., C _{M−1, i} )”, the element “c _{m, i} ” of the complex number sequence Ci is For example, it is expressed by Equation 21 below.

・・・（数式２１）

... (Formula 21)

Here, the _{c m, i} represented by formula 21, the frequency component of the i-th waveform during the _{sweep, c m,} the frequency of the _i from the DC component of 0 [Hz], for the sampling frequency _{f s} It is decomposed into components up to f _s / 2 [Hz] which is the Nyquist frequency. Further, the frequency interval between the individual frequency components is “1 / (T _B −T _S )” [Hz], and the distance interval is “L _R ” expressed by Equation 17 above. Therefore, the distance “L” [m] indicated by _{cm, i} represented by Equation 21 is represented by Equation 22 below, for example.

・・・（数式２２）

... (Formula 22)

  Therefore, when the frequency conversion unit 104 performs frequency conversion of the beat signal using Fourier transform, the detection apparatus 100 can detect movements in objects having different distances.

  In the above description, the window of the sequence for performing the discrete Fourier transform is matched with the sweep interval. Here, it is not always necessary that the window of the sequence for performing the discrete Fourier transform and the sweep section coincide with each other. However, the detection device shown in the above equation 18 with respect to the phase of each frequency component obtained as a result of the discrete Fourier transform. In order to maintain a linear relationship with the distance between the object 100 and the object, it is necessary to maintain a relative relationship between the window of the sequence for performing frequency conversion and the sweep interval. Therefore, the frequency conversion unit 104 performs frequency conversion for each sweep section with respect to repetition of the sweep section.

  For example, as described above, the frequency conversion unit 104 performs frequency conversion of the beat signal using Fourier transform. Then, the frequency converting unit 104 outputs the beat signal subjected to frequency conversion to the motion detecting unit 106.

Note that the processing in the frequency conversion unit 104 according to the first embodiment of the present invention is not limited to the above. For example, the frequency conversion unit 104 may limit the space in which the object is detected, that is, the maximum distance between the detection apparatus 100 and the target object may be limited to “L _max ”.

When the maximum distance between the detection apparatus 100 and the target object is “L _max ”, a spherical space having a radius L _max centered on the detection unit 102 is a space for detecting an object, but the actual object The space in which the detection is performed depends on the directivity related to the transmission of the transmission signal and the directivity related to the reception of the reception signal. For example, when the directivity is narrowed within a range of 45 degrees to the left and right from the front surface of the Doppler sensor included in the detection unit 102, the fan-shaped space defined by L _{max in} the range of 45 degrees to the left and right detects the object. It becomes space.

Frequency converting unit 104, a maximum of m that satisfies _{L (m) <L max} as _{m max,} m = 0, _..., by performing an analysis within the _{m max,} the detection device 100, the detection of an object It is possible to reduce the influence of disturbance elements due to reflection of an object outside the space. Therefore, the frequency conversion unit 104, a maximum of m that satisfies _{L (m) <L max} as _{m max,} m = 0, _..., by performing an analysis within the _{m max,} detection device 100, the object of the The motion detection accuracy can be further improved.

  Further, when the carrier wave is a microwave, a large detection accuracy improvement effect can be obtained by limiting the space in which the object is detected as described above. For example, since the microwave easily passes through a wooden structure, for example, when the carrier wave is a microwave, the detection unit 102 transmits a high-output transmission signal or increases the reception sensitivity of the reception signal. There is an increased possibility of being affected by a space that is not originally the object of object motion detection. On the other hand, in order to detect the minute movement of the object more strictly, increasing the output of the transmission signal and the reception sensitivity of the reception signal is effective in increasing the gain of the signal. As described above, since it is possible to reduce the influence of disturbance elements by limiting the space in which the object is detected, the detection unit 102 outputs the transmission signal by limiting the space in which the object is detected. Even if the reception sensitivity of the received signal is increased, it is not greatly affected by disturbance factors. Therefore, since the trade-off as described above in the case where the carrier wave is a microwave can be eliminated, it is possible to obtain a large detection accuracy improvement effect by limiting the space in which the object is detected as described above. it can.

  The motion detection unit 106 plays a role of leading the process (3) (motion detection process), calculates the phase shift amount of the beat signal for each sweep section, and based on the calculated phase shift amount, Detect the movement of the object.

More specifically, the motion detection unit 106 determines the frequency of the object based on the temporal change in the phase of the beat signal for each frequency component _{cm, i} after frequency conversion in the beat signal transmitted from the frequency conversion unit 104. Detect motion.

  For example, when there is no movement of an object present in the space, that is, when only a stationary object is present in the space, the beat signal is obtained at every sweep interval, regardless of the phase of the transmission signal, according to Equation 15 and Equation 16. The frequency, phase, and amplitude are determined. In addition, since the frequency, phase, and amplitude of the beat signal can be separated by distance by frequency conversion such as discrete Fourier transform in the frequency conversion unit 104, the motion detection unit 106 analyzes time variation by frequency component. The presence or absence of the movement of the object can be detected for each distance.

In the beat signal transmitted from the frequency converting unit 104, the time _{(T T} × j) the frequency components obtained by the initiated swept processed _{c m, j} is related to the distance _{L (m) = m · L} R objects around This corresponds to information in time (T _T × j). Here, the frequency component _{cm, j} is a complex number that is uniquely determined if there is no moving object in the vicinity of the distance L (m). In practice, however, the frequency component _{cm, j} fluctuates slightly due to various error factors. Due to the influence of drift due to temperature characteristics of an RF (Radio Frequency) circuit included in 102, there may be a large fluctuation in the long term.

  Therefore, the motion detection unit 106 determines that the object is moving when, for example, a large-scale change in the phase shift amount occurs in a short period in order to allow the above-described minute fluctuation and long-time fluctuation. In addition, as shown in the above equation 16, the minute fluctuation as described above can greatly affect the phase shift amount of the beat signal. Therefore, the motion detection unit 106 extracts a change in the phase shift amount, for example, It is determined whether or not the phase shift amount has changed due to the movement of.

More specifically, when the m-th frequency component _{cm, j} is obtained by the (j + 1) -th sweep process, the motion detection unit 106, for example, selects the m-th frequency component _{cm, j} and the past Processing is performed using time-series data combined with frequency components obtained by the sweep processing. Hereinafter, the motion detection unit 106, time series collected frequency components obtained by the 100 times of sweep process _{C m, j = (c m} , j-99, c m, j-98, ···, c m _{, J−1} , _{cm, j} ), an example of processing in the motion detection unit 106 will be described using a case where processing is performed as an example.

The phase shift amount series of frequency components in the time series C _{m, j} is Φ _{m, j} = (om _{, j−99} , om _{, j−98} ,..., Om _{, j−1} , om _{, j} ). Here, o _{m, j} is o _{m, j} = arg (c _{m, j} ), and “arg” is an operation for obtaining a declination on the complex plane, and arctan is used.

Motion detection unit 106, the time series _{C m,} the average value of the m-th frequency component in the _{j "c m, j} '' from the argument of the _{average" o m, j} 'is calculated. " In addition, the motion detection unit 106 detects the deviation angle deviation D _{m, j} = ( _{dm, j− of} each element om _{, k} (where k = j−99, j−98,..., J). ₉₉ , dm _{, j−98} ,..., _{Dm, j−1} , dm _{, j} ) ( _where dm _{, k} = om _{, k−} om _{, j} ′) are ± π [rad ] In the range of].

Then, for example, when the magnitude of the variance value σ ² _{Dm, j} of the deviation amount D _{m, j} of the declination is equal to or greater than a predetermined threshold (or the magnitude of the variance value σ ² _{Dm, j} ) Is greater than a predetermined threshold value), it is determined that there is a motion in the object corresponding to the m-th frequency component (the object whose distance from the detection device 100 is near L [m]). Further, the motion detecting unit 106, for example, when the magnitude of the variance value σ ² _{Dm, j} of the deviation amount D _{m, j} of the declination is smaller than a predetermined threshold (or the magnitude of the variance value σ ² _{Dm, j} ). Is less than or equal to a predetermined threshold value), it is not determined that an object corresponding to the m-th frequency component (an object in the vicinity of L [m] from the detection apparatus 100) has movement. The predetermined threshold value may be a fixed value defined in advance, or may be a variable value that can be changed by the user of the detection apparatus 100.

  Further, when the phase shift amount of the beat signal changes greatly, the beat signal amplitude is also affected. Therefore, the motion detection unit 106 can further detect the motion of the object based on the amplitude of each frequency component in the beat signal.

More specifically, for example, if the amplitude of the m-th frequency component in the beat signal is “v _{m, j} ”, v _{m, j} is represented by v _{m, j} = | c _{m, j} |. . Therefore, the motion detection unit 106 obtains the average value “vm _{, j} ′” and the variance value “σ ² _{Vm, j} ” in the same manner as the deflection angle om _{, j} on the complex plane, and sets a predetermined threshold value. By performing the threshold processing used, it is possible to detect the presence or absence of movement of the object based on the amplitude of each frequency component in the beat signal.

  Here, the phase of the frequency component of the beat signal having a small amplitude is likely to change due to the influence of noise or the like. The motion detector 106 detects the motion of the object based on the phase shift amount of the beat signal and the amplitude of the frequency component in the beat signal, so that the motion detector 106 detects the motion of the object with higher accuracy. can do.

As a method for detecting the motion of an object based on the amount of phase shift of the beat signal and the amplitude of the frequency component in the beat signal, for example, a machine learning device such as SVM (Support Vector Machine) is used. The deviation value D _{m, j} variance value σ ² _{Dm, j} , the average amplitude value v _{m, j} ′, and the amplitude variance value “σ ² _{Vm, j} ” are used as input vectors, and the presence or absence of motion is learned as a teacher signal. A method is mentioned. Needless to say, the method of detecting the movement of the object based on the phase shift amount of the beat signal and the amplitude of the frequency component in the beat signal is not limited to the above.

The motion detection unit 106 performs, for example, the above-described process, and based on the phase shift amount of the beat signal (or the phase shift amount of the beat signal and the amplitude of the frequency component in the beat signal), the distance L [m] Detects the movement of objects in the vicinity. Further, the motion detection unit 106 can detect the motion of the object for each distance corresponding to each m by performing processing for each m in the range of m = 0,..., M _max , for example.

  In addition, the motion detection unit 106 may record data indicating the motion detection result on a recording medium such as a storage unit (not shown), or may present the motion detection result to the user. Examples of the method of presenting the motion detection result to the user include visual presentation displayed on a display screen such as a display unit (not shown) and auditory presentation presented by voice (including music). It is done. The motion detection unit 106 can also transmit data indicating the motion detection result to an external device via a communication unit (not shown).

  The detection apparatus 100 according to the first embodiment of the present invention includes, for example, a detection unit 102, a frequency conversion unit 104, and a motion detection unit 106, and thereby relates to the detection method according to the embodiment of the present invention. Processing (1) (detection processing) to processing (3) (motion detection processing) is performed. Therefore, the detection apparatus 100 can improve the detection accuracy of the movement of the object.

  Further, the detection apparatus 100 can detect the movement of the object for each distance from the detection apparatus 100 by performing frequency conversion processing in the frequency conversion unit 104.

  For example, the detection apparatus 100 may detect the movement of the object for each sweep process in the detection unit 102, and the process related to the detection of the movement of the object may be performed in the time direction or the frequency direction (that is, the distance direction). You may skip the process. By detecting the movement of the object for each sweep process, the detection apparatus 100 can detect the movement of the object by time. Further, by thinning out the processing related to the detection of the movement of the object in the time direction and the frequency direction (that is, the distance direction), the processing amount related to the detection of the movement of the object can be reduced.

[Modification of Detection Device According to First Embodiment]
The configuration of the detection apparatus according to the first embodiment of the present invention is not limited to the configuration shown in FIG. For example, the detection apparatus according to the first embodiment of the present invention may be configured without the detection unit 102. In the case of the above configuration, the detection device according to the modification of the first embodiment of the present invention includes, for example, an external device including an FMCW type Doppler sensor connected via a network (or directly). A beat signal output from an external device such as a detection device is received, and the movement of the object is detected based on the received beat signal. Moreover, even if the detection apparatus according to the modification of the first embodiment of the present invention includes the detection unit 102, the detection apparatus receives the beat signal output from the external apparatus, and based on the received beat signal It is possible to detect the movement of the object.

  In the case of the above configuration, the detection apparatus according to the modification of the first embodiment of the present invention and an external apparatus such as a detection apparatus provided in a space for detecting an object are provided. A detection system capable of performing processing related to the detection method according to the embodiment is realized.

  Further, the detection apparatus according to the first embodiment of the present invention may be configured not to include the frequency conversion unit 104, for example. In the case of the above configuration, the detection device according to the modification of the first embodiment of the present invention detects the movement of an object corresponding to a single distance. Moreover, in the case of said structure, the detection apparatus which concerns on the modification of the 1st Embodiment of this invention can also detect the vitality of a person (an example of an object), for example. In addition, the detection apparatus according to the modification of the first embodiment of the present invention can be configured such that the frequency conversion unit 104 selectively performs frequency conversion processing according to settings based on user operations, for example. is there.

(Detection device according to the second embodiment)
FIG. 4 is an explanatory diagram showing an example of the configuration of the detection apparatus 200 according to the second embodiment of the present invention. The detection apparatus 100 includes, for example, a detection unit 102, a frequency conversion unit 104, and a motion detection unit 202.

  The detection device 200 according to the second embodiment shown in FIG. 4 has basically the same configuration as the detection device 100 according to the first embodiment shown in FIG. 1, but the first embodiment shown in FIG. Compared with the detection apparatus 100 according to FIG. 4, the detection apparatus 200 according to the second embodiment shown in FIG.

Similar to the motion detection unit 106 according to the first embodiment, the motion detection unit 202 plays a leading role in performing the process (3) (motion detection process), and shifts the phase of the beat signal for each sweep section. The amount is calculated, and the motion of the object is detected based on the calculated phase shift amount. More specifically, the motion detection unit 202, like the motion detection unit 106 according to the first embodiment, each frequency component _{cm, i} after frequency conversion in the beat signal transmitted from the frequency conversion unit 104. The motion of the object is detected based on the temporal change in the phase of the beat signal. In addition, the motion detection unit 202 detects the motion of the object based on the phase shift amount of the beat signal and the amplitude of the frequency component in the beat signal, similarly to the motion detection unit 106 according to the first embodiment. Also good.

  As described above, for example, when there is no motion in an object existing in the space, that is, when only a stationary object is present in the space, the sweeping is performed from Equation 15 and Equation 16 regardless of the phase of the transmission signal. The frequency, phase, and amplitude of the beat signal are determined at each interval. Here, the frequency, phase, and amplitude of the beat signal can be separated by distance by frequency conversion such as discrete Fourier transform in the frequency converter 104, but the distance resolution is sufficiently high in frequency conversion by discrete Fourier transform or the like. It may not be possible. For this reason, even if a frequency transform such as a discrete Fourier transform is used, there is a risk that it is insensitive to a minute change in distance.

  On the other hand, if attention is paid to the change in the phase shift amount of the beat signal, it is possible to observe the change in the distance finer than Expression 18 by the change in the phase shift amount of the beat signal. Therefore, the motion detection unit 202 detects the presence or absence of the motion of the object for each distance by analyzing the temporal variation of the phase shift amount of the beat signal for each frequency component.

As described above, the frequency component _{cm, j} obtained by the sweep process started at time (T _T × j) in the beat signal transmitted from the frequency conversion unit 104 is the distance L (m) = m · L _This corresponds to information in time (T _T × j) related to an object near _R. Here, the frequency component _{cm, j} is a complex number that is uniquely determined if there is no moving object in the vicinity of the distance L (m), but in reality, minute fluctuations or long-term fluctuations may occur.

  Therefore, in order to allow such minute fluctuations and long-time fluctuations as described above, the motion detection unit 202, for example, in the same manner as the motion detection unit 106 according to the first embodiment, has a large short-term change in the phase shift amount. If this occurs, it is determined that the object has movement. In addition, since the minute fluctuation as described above can greatly affect the phase shift amount of the beat signal as shown in the mathematical expression 16, the motion detection unit 202 is, for example, the motion detection unit according to the first embodiment. Similarly to 106, a change in the phase shift amount is extracted, and it is determined whether the phase shift amount has changed due to the movement of the object.

  Further, for example, when the order of the first term and the second term of Equation 14 is significantly different as in the case where the detection unit 102 transmits a transmission signal using a microwave as a carrier wave, as shown in Equation 18 above, The phase shift amount of the beat signal can be approximated so as to have a linear relationship with the distance between the detection apparatus 100 and the object. Therefore, the motion detection unit 202 can grasp a minute change in the movement of the object as a change in the phase shift amount of the beat signal.

  Therefore, the motion detection unit 202 detects, for example, the movement of the chest of a person (an example of an object) and estimates respiration, or detects the movement of the heart, blood vessels, and pulses of a user (an example of an object) Can be estimated.

Taking the case where the m-th frequency component _{cm, j} is obtained by the (j + 1) -th sweep processing as an example, motion detection is performed by performing the same processing as the motion detection unit 106 according to the first embodiment. The unit 202 can obtain the phase shift amount of the mth frequency component from o _{m, j} = arg (c _{m, j} ).

The phase shift amount O _b of the beat signal for the sweep interval, it is possible to approximate the distance and the linear relation between the detector 100 and the object from the above equation 18 is obtained by frequency transformation for each repetition of the sweep interval Similarly, the phase shift amount om _{, j of} each frequency component can be regarded as having a linear relationship with the distance between the detection apparatus 100 and the object. When the amount of change in the phase shift amount that can occur each time the sweep section is repeated is taken with respect to the phase shift amount om _{, j of} each frequency component, the time derivative of the distance is linear as well as the speed. A variable pm _{, j} that can be regarded as a relationship can be calculated. Further, the variable pm _{, j} is expressed by the following Expression 23, for example.

・・・（数式２３）

... (Formula 23)

In Equation 23, n is selected so that the variable pm _{, j} falls within the range of ± π. Here, if the object moves such that the phase change in the beat signal exceeds one cycle, the motion continuity is lost, but the motion detection unit 202 detects that there is motion itself. be able to. When the object moves slightly, the motion detection unit 202 can detect the motion while maintaining continuity.

  Note that there is no particular need to consider when detecting the movement of a person or the like, but if the speed is very large compared to the frequency change due to sweeping, for example, the phase change due to the Doppler effect (and due to the phase change) Frequency change). In the following, an example of processing in the motion detection unit 202 will be described by taking as an example a case where the motion detection unit 202 detects the motion of a person (an example of an object).

For example, when detecting a motion of a person (an example of an object) due to respiration, the motion is a reciprocating motion of about 0.3 [Hz], and therefore a time series P _m that is a set of values for each sweep of pm _{, j. , J} = (..., P _{m, j−1} , p _{m, j} ), the motion detector 202 can detect the presence or absence of breathing and the pace of breathing. . Here, the motion detection unit 202 performs discrete Fourier transform, for example, and breathing is performed when the power of the frequency component in the vicinity of 0.3 [Hz] is sufficiently high (for example, determined by threshold processing). It may be determined that there is a bandpass filter having a center frequency of 0.3 [Hz], and when the amplitude of the output of the bandpass filter is high (for example, it is determined by threshold processing). It may be determined that there is breathing.

In addition, since the body fluctuation at rest in a person (an example of an object) is a movement that does not change depending on the location, when viewed from the detection unit 102, the movement of a plurality of parts that repeats approach and separation finely is repeated. Observed as a mixture. The frequency component in the beat signal caused by the above movement causes a change in acceleration obtained by differentiating the speed. Therefore, the motion detection unit 202 obtains a parameter q _{m, j} having a linear relationship with the acceleration expressed by, for example, the following Equation 24 by first-order differentiation of the variable pm _{, j} .

・・・（数式２４）

... (Formula 24)

Motion detecting unit 202, the parameter _{q m,} the time series is a set of values for each sweep _{j Q m, j = (···} , q m, j-2, q m, j-1, q m, j ) ² dispersion value σ ² _{qm, j} is calculated for each sweep. The motion detection unit 202 then moves when the variance value σ ² _{qm, j} is greater than or equal to a predetermined threshold (or when the variance value σ ² _{qm, j} is greater than the predetermined threshold). Judge that there is. Therefore, the motion detection unit 202 can detect minute fluctuations in a person (an example of an object), for example.

In addition, the heartbeat of a person (an example of an object) can be easily characterized by jerk. Since the jerk is a second-order derivative of speed, the motion detection unit 202 performs a second-order differentiation of the variable pm _{, j} , for example, a parameter r having a linear relationship with the jerk represented by the following Expression 25. Obtain _{m, j} .

・・・（数式２５）

... (Formula 25)

Motion detecting unit 202, the parameter _{r m,} the time-series _R m is the set of values for each sweep _{j, j = (···, r} m, j-2, r m, j-1, r m, j ) ² variance value σ ² _{rm, j} is calculated for each sweep. Then, the motion detection unit 202 detects the heartbeat of a person (an example of an object) by determining the intensity of jerk by threshold processing or the like, and further determining the periodicity of about 1 [Hz] by autocorrelation or the like. Can do.

The motion detection unit 202 performs, for example, the above-described processing, and based on the phase shift amount of the beat signal (or the phase shift amount of the beat signal and the amplitude of the frequency component in the beat signal), the distance L [m] Detects the movement of objects in the vicinity. Further, the motion detection unit 106 can detect the motion of the object for each distance corresponding to each m by performing processing for each m in the range of m = 0,..., M _max , for example.

  In addition, the motion detection unit 202 calculates a feature value indicating a feature of motion change in the space based on the temporal change component of the phase shift amount, and based on the calculated feature value, for example, a person (object It is possible to detect minute fluctuations in an example) and a heartbeat of a person (an example of an object). Here, the feature value indicating the feature of the movement change in the space indicates at least one of speed, acceleration, and jerk component. That is, the motion detection unit 202 may calculate, for example, any one of speed, acceleration, and jerk components as a feature value that indicates the characteristics of the change in motion in the space, or the speed, acceleration, and jerk components. A plurality of values among them may be calculated as feature values indicating the characteristics of changes in motion in the space.

  Similarly to the motion detection unit 106 according to the first embodiment, the motion detection unit 202 transmits data indicating the motion detection result to a recording medium such as a storage unit (not shown). It may be recorded, or a motion detection result may be presented to the user. The motion detection unit 202 can also transmit data indicating the detection result of the motion to an external device via a communication unit (not shown), similar to the motion detection unit 106 according to the first embodiment. It is.

  The detection apparatus 200 according to the second embodiment of the present invention includes, for example, a detection unit 102, a frequency conversion unit 104, and a motion detection unit 202. Here, the detection apparatus 200 has basically the same configuration as that of the detection apparatus 100 according to the first embodiment shown in FIG. 1, and the process (1) according to the detection method according to the embodiment of the present invention. Processes (detection process) to (3) (motion detection process) are performed. Therefore, the detection device 200 can improve the detection accuracy of the movement of the object, similarly to the detection device 100 according to the first embodiment shown in FIG.

  Further, the detection device 200 can detect the movement of the object for each distance from the detection device 200 by performing frequency conversion processing in the frequency conversion unit 104, as in the detection device 100 according to the first embodiment. it can.

  Similarly to the detection device 100 according to the first embodiment, the detection device 200 thins out processing related to detection of an object in the time direction and the frequency direction (that is, the distance direction), thereby The amount of processing related to motion detection can be reduced.

  In addition, the detection device 200 calculates a feature value indicating a feature of a change in motion in space based on the temporal change component of the phase shift amount, and based on the calculated feature value, for example, a person (object It is possible to detect minute movements of an object such as minute fluctuations in an example) and a heartbeat of a person (an example of an object).

[Modification of Detection Device According to Second Embodiment]
Note that the configuration of the detection apparatus according to the second embodiment of the present invention is not limited to the configuration shown in FIG. For example, the detection device according to the second embodiment of the present invention can have the same configuration as the configuration according to the modified example of the detection device according to the first embodiment of the present invention described above.

  As described above, the detection apparatus according to the embodiment of the present invention can perform, for example, the process (1) (detection process) to the process (3) as a process related to the detection method according to the embodiment of the present invention ( Motion detection process), process (2) (frequency conversion process) and process (3) (motion detection process), process (1) (detection process) and process (3) (motion detection). Process) or the process (3) (motion detection process). Here, the detection apparatus according to the embodiment of the present invention obtains a beat signal by the process (1) (detection process) or from an external apparatus, and in the process (3), the phase of the beat signal is acquired. The movement of the object is detected by regarding the temporal change of the shift amount as the movement component of the object in space. Here, when the temporal change in the phase shift amount of the beat signal is regarded as the motion component of the object in space, the signal-to-noise ratio of the signal may deteriorate even if the object to be detected moves finely. Can be reduced more than when conventional techniques are used.

  Therefore, the detection apparatus according to the embodiment of the present invention can improve the detection accuracy of the movement of the object.

Further, examples of application of the detection apparatus according to the embodiment of the present invention include the following examples. Needless to say, the application example of the detection apparatus according to the embodiment of the present invention is not limited to the example shown below.
The detection device according to the embodiment of the present invention is provided in a chair or a bed, and measures (observes) a heartbeat when a person goes to sleep or sits down.
The detection device according to the embodiment of the present invention is provided in an office desk and measures (observes) heart rate variability of a person who is working at a desk.
The detection apparatus according to the embodiment of the present invention is provided in a hospital and measures (observes) heart rate variability of a patient waiting for a medical examination. Therefore, based on the detection apparatus according to the embodiment of the present invention, it is possible to specify a patient to be preferentially examined.

  As mentioned above, although the detection apparatus was mentioned and demonstrated as embodiment of this invention, embodiment of this invention is not restricted to this form. Embodiments of the present invention include, for example, computers such as PCs (Personal Computers) and servers, communication devices such as mobile phones and smartphones, video / music playback devices (or video / music recording / playback devices), game machines, vehicles, and the like. It can be applied to various devices.

(Program according to an embodiment of the present invention)
A program for causing a computer to function as the detection device according to the embodiment of the present invention (for example, the process (3) (motion detection process) or the process (2) (frequency conversion process) and the (3 ) (A program capable of executing processing related to the detection method according to the embodiment of the present invention, such as processing (motion detection processing)), it is possible to improve the detection accuracy of the motion of the object.

  Here, the computer includes, for example, a control unit corresponding to an MPU, a storage unit corresponding to a hard disk, an input unit corresponding to a mouse, and a display unit. The program stored in the hard disk is read by the MPU, and the MPU executes an instruction described in the program. By executing the read program, the computer can execute processing according to the detection method according to the embodiment of the present invention.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above, it has been shown that a program (computer program) for causing a computer to function as the detection device according to the embodiment of the present invention is provided. However, the embodiment of the present invention further stores the program. The recorded recording medium can also be provided.

  The configuration described above shows an example of the embodiment of the present invention, and naturally belongs to the technical scope of the present invention.

100, 200 Detection device 102 Detection unit 104 Frequency conversion unit 106, 202 Motion detection unit

Claims (15)

  Based on a beat signal having a frequency difference between a transmission signal whose frequency changes in a constant sweep section and a reception signal received in response to transmission of the transmission signal, the phase of the beat signal for each sweep section A detection apparatus comprising: a motion detection unit that calculates a shift amount and detects a motion of an object based on the calculated phase shift amount. A detector that transmits the transmission signal and outputs the beat signal based on the transmission signal and the reception signal;
The detection apparatus according to claim 1, wherein the motion detection unit calculates a phase shift amount of the beat signal output from the detection unit. A frequency conversion unit that converts the frequency of the beat signal for each sweep interval;
The detection device according to claim 1, wherein the motion detection unit calculates a phase shift amount of the beat signal for each frequency in the beat signal subjected to frequency conversion.   The detection device according to claim 3, wherein the motion detection unit detects a motion of an object based on a variation in a phase shift amount calculated for each frequency. The motion detection unit generates time-series data of the phase shift amount for each frequency,
The motion of the object is detected based on a temporal change component of the phase shift amount of the beat signal for each frequency calculated based on the time-series data for each frequency. Detection device. The motion detector is
Generate time series data of the phase shift amount,
The detection apparatus according to claim 1, wherein the movement of the object is detected based on a temporal change component of the phase shift amount of the beat signal calculated based on the time series data.   The detection according to claim 5 or 6, wherein the motion detection unit calculates a feature value indicating a feature of motion change in space based on a temporal change component of the phase shift amount. apparatus.   The detection device according to claim 7, wherein the feature value indicates at least one of speed, acceleration, and jerk components.   The detection device according to claim 1, wherein the motion detection unit detects a motion of an object based on variation in the phase shift amount.   The detection device according to claim 4 or 9, wherein the motion detection unit further detects a motion of an object based on an amplitude of each frequency component in the beat signal.   Based on a beat signal having a frequency difference between a transmission signal whose frequency changes in a constant sweep section and a reception signal received in response to transmission of the transmission signal, the phase of the beat signal for each sweep section A detection method comprising: calculating a shift amount, and detecting a motion of an object based on the calculated phase shift amount. Further comprising the step of transmitting the transmission signal and outputting the beat signal based on the transmission signal and the reception signal;
The detection method according to claim 11, wherein in the step of detecting the movement of the object, a phase shift amount of the beat signal output in the step of outputting the beat signal is calculated. Further comprising the step of frequency converting the beat signal for each sweep interval;
The detection method according to claim 11, wherein in the step of detecting the movement of the object, a phase shift amount of the beat signal is calculated for each frequency in the beat signal subjected to frequency conversion. Further comprising the step of transmitting the transmission signal and outputting the beat signal based on the transmission signal and the reception signal;
The detection method according to claim 13, wherein in the frequency converting step, the beat signal output in the step of outputting the beat signal is frequency-converted. Based on a beat signal having a frequency difference between a transmission signal whose frequency changes in a constant sweep section and a reception signal received in response to transmission of the transmission signal, the phase of the beat signal for each sweep section A program for causing a computer to function as means for calculating a shift amount and detecting a motion of an object based on the calculated phase shift amount.

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