RESPONDER AND POSITIONING SYSTEM

A responder that receives an interrogation wave from an interrogator and transmits a response wave to the interrogator includes a plurality of antennae receiving the interrogation wave, a reference signal generator generating a reference signal, a plurality of modems outputting quadrature phase amplitudes based on reception signals output from the antennae when the interrogation wave is received and the reference signal, a parallel-time-series signal converter converting a parallel signal having the quadrature phase amplitude output from each of the modems into a time-series signal, a frequency divider outputting a frequency division signal having a frequency and a phase for detecting the time-series signal, a multiplier outputting a multiplication signal obtained by multiplying the time-series signal by the frequency division signal, and a beam selector determining an arrival direction of the interrogation wave based on the multiplication signals.

The present application is based on, and claims priority from JP Application Serial Number 2023-129398, filed Aug. 8, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a responder and a positioning system.

2. Related Art

In related art, various responders that receive interrogation waves from interrogators and transmit response waves to the interrogators are used. In such a responder, an interrogation wave reaches the responder through a plurality of propagation paths of a direct wave, a reflected wave, and the like, and thereby, a phase difference corresponding to a difference in propagation distance is generated. There is known so-called multipath that the components of the wave overlap to cause a decrease in reception intensity, a phase shift, or the like, and adversely affect the quality of a received signal in the responder. In order to suppress the influence of multipath, for example, JP-A-2000-91844 proposes a method of separating a direct wave and a reflected wave from an interrogation wave by measuring an arrival direction and an arrival delay time of a signal arriving at an antenna and obtaining a PDA (Power, Delay, Angle) profile.

JP-A-2000-91844 is an example of the related art.

However, in the responder disclosed in JP-A-2000-91844, in order to obtain a PDA profile, it is necessary to execute a calculation flow such as an FFT-MUSIC method using fast Fourier transform (FFT). Further, in order to extract a signal arriving from a specific direction based on the PDA profile, it is necessary to calculate a weight to give directivity. As described above, in order to determine the arrival direction of the signal based on the PDA profile, a large number of product-sum calculations are required and take a considerable time. In the responder of related art as disclosed in JP-A-2000-91844, the large number of product-sum calculations are performed by software.

SUMMARY

According to an aspect of the present disclosure, there is provided a responder that receives an interrogation wave from an interrogator and transmits a response wave to the interrogator, including a plurality of antennae receiving the interrogation wave, a reference signal generator generating a reference signal, a plurality of modems outputting quadrature phase amplitudes based on reception signals output from the antennae when the interrogation wave is received and the reference signal, a parallel-time-series signal converter converting a parallel signal having the quadrature phase amplitude output from each of the modems into a time-series signal, a frequency divider outputting a frequency division signal having a frequency and a phase for detecting the time-series signal, a multiplier outputting a multiplication signal obtained by multiplying the time-series signal by the frequency division signal, and a beam selector determining an arrival direction of the interrogation wave based on the multiplication signals.

DESCRIPTION OF EMBODIMENTS

First, the present disclosure will be schematically described.

A responder in a first aspect of the present disclosure for solving the above problem is a responder that receives an interrogation wave from an interrogator and transmits a response wave to the interrogator, including a plurality of antennae receiving the interrogation wave, a reference signal generator generating a reference signal, a plurality of modems outputting quadrature phase amplitudes based on reception signals output from the antennae when the interrogation wave is received and the reference signal, a parallel-time-series signal converter converting a parallel signal having the quadrature phase amplitude output from each of the modems into a time-series signal, a frequency divider outputting a frequency division signal having a frequency and a phase for detecting the time-series signal, a multiplier outputting a multiplication signal obtained by multiplying the time-series signal by the frequency division signal, and a beam selector determining an arrival direction of the interrogation wave based on the multiplication signals.

According to this aspect, the responder includes the antennae, the reference signal generator, the modems, the parallel-time-series signal converter, the frequency divider, the multiplier, and the beam selector. Thereby, calculation for suppressing the influence of multipath using fast Fourier transform or the like may be performed using hardware instead of software. Accordingly, the influence of multipath can be suppressed in a short time.

In the responder in a second aspect of the present disclosure according to the first mode, the frequency divider changes a frequency division ratio of the frequency division signal with time, and the beam selector determines the arrival direction based on intensity of the multiplication signals.

According to the mode, the arrival direction is determined based on the intensity of the multiplication signals generated based on the frequency division signals having the frequency division ratios changed with time. Therefore, the arrival direction can be determined by serial detection.

In the responder in a third aspect of the present disclosure according to the first aspect, the frequency divider outputs a plurality of the frequency division signals having different frequency division ratios from one another, and the beam selector determines the arrival direction based on intensity of the multiplication signals.

According to the mode, the arrival direction is determined based on the intensity of the multiplication signals generated based on the plurality of frequency division signals having different frequency division ratios from one another. Therefore, the arrival direction can be determined by parallel detection.

The responder in a fourth aspect of the present disclosure according to the first aspect includes an arrival direction memory unit storing a frequency division ratio as arrival direction information of the interrogation wave output from the beam selector, and a quadrature phase amplitude memory unit storing the quadrature phase amplitude, wherein the frequency divider outputs a response wave frequency division signal having a frequency corresponding to the frequency division ratio as the arrival direction information to the multiplier, the multiplier multiplies the response wave frequency division signal by a response wave time-series signal based on the quadrature phase amplitude stored in the quadrature phase amplitude memory unit and outputs a response wave multiplication signal to the parallel-time-series signal converter, the parallel-time-series signal converter converts the response wave multiplication signal into a response wave parallel signal and outputs the response wave parallel signal to the modem, the modem generates the response wave having a response wave quadrature phase amplitude corresponding to the response wave parallel signal based on a response wave reference signal, and the plurality of antennae transmit the response wave to the interrogator.

According to the mode, the frequency divider outputs the response wave frequency division signal to the multiplier, the multiplier outputs the response wave multiplication signal to the parallel-to-time-series signal converter, the parallel-to-time-series signal converter converts the response wave multiplication signal into the response wave parallel signal and outputs the response wave parallel signal to the modem, the modem generates the response wave having the response wave quadrature phase amplitude, and the antenna transmits the response wave to the interrogator. According to the configuration, the response wave may be preferably transmitted to the interrogator while suppressing the influence of multipath in a short time.

The responder in a fifth aspect of the present disclosure according to the first aspect includes a reception time discriminator discriminating a reception time, at which the interrogation wave is received by the antenna, based on a predetermined signal component contained in the multiplication signal.

According to the mode, the responder includes the reception time discriminator discriminating the reception time at which the interrogation wave is received by the antenna. Therefore, the reception time of the interrogation wave can be grasped, and for example, the timing of transmitting the response wave to the interrogator can be preferably set based on the reception time of the interrogation wave.

The responder in a sixth aspect of the present disclosure according to the fourth aspect further includes a reception time discriminator discriminating a reception time, at which the interrogation wave is received by the antenna, based on a predetermined signal component contained in the multiplication signal, wherein the beam selector determines an output time of the response wave frequency division signal based on the reception time.

According to the mode, the responder includes the reception time discriminator discriminating the reception time when the interrogation wave is received by the antenna, and the beam selector determines the output time of the response wave frequency division signal based on the reception time. Therefore, the timing of transmitting the response wave to the interrogator may be preferably set.

A positioning system in a seventh aspect of the present disclosure includes the responder according to any one of the first to sixth modes, the interrogator, a distance calculator calculating a distance from the interrogator to the responder, and a position detector measuring a position of the responder, wherein the interrogator outputs the interrogation wave containing a predetermined signal pattern and having directionality, the distance calculator calculates the distance from the interrogator to the responder based on a difference between a time when the interrogation wave is transmitted from the interrogator and a time when the response wave transmitted from the responder is received by the interrogator and a predetermined holding time, and the position detector measures the position of the responder based on the distance.

According to the mode, the interrogator outputs the interrogation wave containing the specific signal pattern, the distance calculator calculates the distance from the interrogator to the responder based on the difference between the time when the interrogation wave is transmitted from the interrogator and the time when the response wave transmitted from the responder is received by the interrogator and the predetermined holding time, and the position detector measures the position of the responder based on the distance. According to the configuration, the position of the responder can be accurately measured.

The positioning system in an eighth aspect of the present disclosure according to the seventh aspect includes a mechanical body having a movable part and a fixed part, wherein the interrogator is provided in the fixed part, and the responder is provided in the movable part.

According to the mode, the interrogator is provided in the fixed part, and the responder is provided in the movable part. According to the configuration, the position of the responder provided in the movable part can be accurately measured.

As below, embodiments according to the present disclosure will be described with reference to the accompanying drawings. A responder100of the present disclosure is a responder that receives an interrogation wave Pt from an interrogator200and transmits a response wave Pr to the interrogator200(seeFIG.2). First, a usage example of the responder100according to one embodiment of the present disclosure will be described with reference toFIG.1.

As shown inFIG.1, when receiving the interrogation wave Pt from the interrogator200, the responder100receives a direct wave directly reaching the responder100from the interrogator200and a reflected wave reflected by an object O and reaching the responder100from the interrogator200. InFIG.1, the direct wave is referred to as a direct wave Pt1, the reflected wave reflected only by an object O1and reaching of the reflected waves is referred to as a reflected wave Pt2, the reflected wave reflected only by an object O2and reaching of the reflected waves is referred to as a reflected wave Pt3, and the reflected wave reflected by the object O1and the object O2and reaching of the reflected waves is referred to as a reflected wave Pt4.

Generally, a reflected wave transmitted from the interrogator200reaches the responder100later than a direct wave. Further, the same applies to a case where the interrogator200receives the response wave Pr returned from the responder100to the interrogator200. Accordingly, radio waves propagated through different paths reach at different times, in other words, when a component of a direct wave and a component of a reflected wave are mixed, and thereby, a reception waveform may become dull and an influence of the so-called multipath may be caused. As a method for suppressing the influence of the multipath, there is a method of separating the direct wave Pt1and the reflected waves Pt2to Pt4from the interrogation wave Pt.

As below, the details of the responder100of one embodiment of the present disclosure that can separate the direct wave and the reflected wave from the interrogation wave Pt will be described with reference toFIGS.2to5. First, an operation when the responder100receives the interrogation wave Pt will be described together with a configuration of the responder100with reference toFIG.2.FIG.2shows both a state in which the interrogation wave Pt having a wavelength λ is received by the responder100and a state in which the response wave Pr having the wavelength λ is transmitted from the responder100. Specifically, a state in which, using the responder100having an array antenna in which receiving surfaces of antennae101are arranged in a planar shape in an X direction and a Y direction orthogonal to the X direction inFIG.2, the interrogation wave Pt is received by the responder100from a direction inclined by an angle θ with respect to a Z direction inFIG.2orthogonal to the receiving surfaces of the antennae101and the response wave Pr is transmitted from the responder100in a direction opposite to the reception direction is shown.

The interrogation wave Pt is, for example, a radio wave (electromagnetic wave) having a waveform obtained by modulation of various kinds of information including ID (IDENTIFICATION) information as an identification number for identifying the responder100to receive and synchronization information by an appropriate method. For the modulation method, phase modulation, amplitude modulation, quadrature frequency division multiplexing, or the like can be selected. For the carrier waves as the interrogation wave Pt and the response wave Pr, microwaves, millimeter waves, terahertz waves, or the like can be used.

The antenna101has a function of receiving the interrogation wave Pt, and a plurality of the antennae are arranged in one dimension (for example, in the X direction inFIG.2) or two dimensions (for example, the X direction and the Y direction intersecting the X direction inFIG.2) at regular intervals to form the array antenna. Although the responder100of the embodiment has the array antenna in which the antennae101are two-dimensionally arranged, in order to simplify the description, the interrogation wave Pt and the response wave Pr inclined only in the X direction with respect to the Z direction are considered. Here, generally, the array antenna is mounted as an array of patch antennas on a substrate and an electric field amplitude distribution AT(xi, t) which vibrates on a surface of the array antenna can be expressed by the following equation (1).

Here, kTis a wave number vector of the interrogation wave Pt. Xiis a vector indicating the position of the i-th antenna from the coordinate axis origin. ω is a carrier wave angular frequency of the interrogation wave Pt. A phase difference φ is a difference between the phase of the interrogation wave Pt and the phase of an LO signal as a signal output by a local oscillator112b, which will be described later, in positions in bidirectional mixers111band111c. When the phase of the interrogation wave Pt is modulated, the phase difference φ contains the modulated phase. Although polarization dependency is not particularly mentioned here, a dual polarized antenna capable of independently receiving polarization components in two orthogonal directions can also be used as necessary.

As shown inFIGS.2and3, modems111are respectively coupled to the individual antennae101. As shown inFIG.3, the modem111includes a bidirectional amplifier111aand the bidirectional mixers111band111c. The modem111amplifies an electric signal output from the antenna101by the bidirectional amplifier111a, and then branches and inputs the electric signal to the bidirectional mixers111band111c. As shown inFIG.3, the bidirectional mixers111band111care coupled to paths104, and as shown inFIG.2, the paths104are coupled to a parallel-time-series signal converter113.

As shown inFIG.3, a reference signal generator112includes the local oscillator112band a ±π/2 shifter112a. The local oscillator112boscillates at a frequency ωLOequal to the carrier wave frequency ω of the interrogation wave Pt, and branches into two transmission lines112c. One becomes an LO signal having an In-phase phase as it is, and the other becomes an LO signal having a quadrature phase delayed by a phase π/2 by the ±π/2 shifter112a. The subsequent lines are coupled by wires having an equal length so as not to generate a phase difference, and the signals are distributed to all the bidirectional mixers (bidirectional mixers111band111c).

According to the configuration, quadrature demodulation at the same phase is performed in all the bidirectional mixers, and an amplitude AI(xi, t) and an amplitude AQ(xi, t) of two orthogonal phase components are output as baseband signals. Hereinafter, a combination of the amplitudes is referred to as “quadrature phase amplitude”. This function is shown using the following equations (2) and (3). In the following equations (2) and (3), the term including ωLOis removed by a filter (not shown) or the like in actual operation, only the term not including ωLOremains, and the information of the quadrature phase amplitude is temporarily held in a state of an analog signal for each corresponding cell in the parallel-time-series signal converter113.

A method of obtaining the arrival direction of the interrogation wave Pt in the responder100of the embodiment will be described below with reference to the flowchart ofFIG.4. First, at step S110, the parallel-time-series signal converter113converts analog signals of quadrature phase amplitude held in parallel in each cell into time-series signals. Specifically, for example, a bucket brigade system as a method of holding an analog signal as charge and sequentially transferring the charge to adjacent cells based on the principle of a charge coupled device (CCD) can be used. As another example, an active matrix system used in a liquid crystal display can be used.

Then, at step S120, the quadrature phase amplitude information is converted into digital data by an A/D converter (not shown), and is sequentially stored in a quadrature phase amplitude memory unit102. Step S120can be performed in parallel with step S110.

Then, at step S130, a multiplier107shown inFIG.2multiplies one or a plurality of alternating-current signals output from a second frequency divider of a frequency divider106shown inFIG.2having a first frequency divider and the second frequency divider at different frequencies by the time-series signal converted by the parallel-time-series signal converter113. As the multiplier107, for example, an analog multiplier including a transistor can be used. As shown inFIG.2, the first frequency divider denoted by a sign “1” is coupled to the parallel-time-series signal converter113, the quadrature phase amplitude memory unit102, and a reception time discriminator108, and the second frequency divider denoted by a sign “2” is coupled to the multiplier107coupled to the parallel-time-series signal converters113and a beam selector103.

Then, at step S140, the beam selector103shown inFIG.2scans the frequency division ratio of the second frequency divider, specifies the frequency division ratio corresponding to the output with the highest intensity of the multiplier107from one or a plurality of multiplication signals, and stores this information in an arrival direction memory unit105shown inFIG.2. Generally, since the component of the direct wave is higher in intensity than the reflected wave, consequently, the processing at step S140specifies the arrival direction of the direct wave. In the scanning of the frequency division ratio of the second frequency divider, the frequency division ratio may be scanned over time. Or, a plurality of one-dimensional antenna arrays arranged in the X direction may be arranged in the Y direction orthogonal to the X direction and direct wave components may be obtained simultaneously in parallel by multiplication of the signals at different frequencies.

A series of operations executed by the parallel-time-series signal converter113, the multiplier107, the beam selector103, and the like from step S110to step S140are equivalent to obtainment of a spatial frequency of the quadrature phase amplitude distributed in the X direction, that is, a Fourier coefficient. That is, steps S110to S140are executed, and thereby, the arrival direction of the direct wave corresponding to the frequency division ratio of the output having the highest intensity can be obtained at a high speed at a fixed time.

The reception time discriminator108shown inFIG.2monitors a pattern of data in the quadrature phase amplitude memory unit102. Then, for example, when the identification number of the responder100as a target is added to the interrogation wave Pt and transmitted by phase modulation or the like, if the identification number of the transmitted interrogation wave Pt matches the identification number of the own station, the responder100concurrently generates a trigger signal for switching from the operation of receiving the interrogation wave Pt to the operation of transmitting the response wave Pr. In a case of use for positioning of the responder100or for measurement of the distance from the interrogator200to the responder100, when a holding time Th from the reception completion time of the interrogation wave Pt to the transmission start time of the response wave Pr is set, the generation of the trigger signal may be adjusted by providing a waiting time so as to satisfy the setting.

Next, a generation process of the response wave Pr in the responder100of the embodiment will be described as below with reference to the flowchart ofFIG.5. First, at step S210, the reference signal generator112detects the trigger signal and, at step S220, the beam selector103sets the frequency division ratio of the second frequency divider of the frequency divider106based on the information stored in the arrival direction memory unit105.

Then, at step S230, the quadrature phase amplitude memory unit102prepares an analog signal of time-series information by, for example, converting the digital information of the stored quadrature phase amplitude into an analog signal by a D/A converter (not shown), and outputs the analog signal to the multiplier107. Then, at step S240, the multiplier107multiplies the output of the second frequency divider of the frequency divider106by the output of the quadrature phase amplitude memory unit102, and transmits the result to the parallel-time-series signal converter113.

Then, at step S250, the parallel-to-time-series signal converter113converts the time-series signal into a parallel signal by the CCD or the active matrix method as is the case with the reception of the interrogation wave Pt, and outputs the parallel signal to the modem111. Then, at step S260, the reference signal generator112inverts the sign of the ±π/2 shifter112aand generates a conjugate LO signal as a time-reversed LO signal. Note that, when expressed by an IQ plane as a plane formed by an In-phase axis and a Quadrature axis, a wave rotates in a direction opposite to that at the time of reception.

Then, at step S270, the modem111mixes the output from the D/A converter (not shown) with the conjugate LO signal, outputs the mixed signal to the antenna101through the bidirectional amplifier111a, and returns the response wave Pr to the interrogator200. Here, the electric field amplitude distribution AR(xi, t) when the response wave Pr is generated can be expressed by the following equation (4) using quadrature phase amplitudes AI(xi, t) and AQ(xi, t).

Here, the sign of the quadrature component sin (ωLOt) of the LO signal is inverted by the sign inversion in the ±π/2 shifter112a. As a result of the series of processing, as shown inFIG.2, the wave number vector KR of the output response wave Pr propagates in the opposite direction to the wave number vector kTat the reception of the interrogation wave Pt.

Strictly, when the equation (1) and the equation (4) are compared, a phase difference of 2φ is generated, and an error occurs in a holding time (holding time th) from the reception completion time of the interrogation wave Pt to the transmission start time of the response wave Pr. When there is a request to correct this, a method of adjusting and correcting the data of the quadrature phase amplitude stored in the memory unit102is conceivable. Alternatively, a phase shifter may be provided immediate downstream of the output of the local oscillator112bfor correction.

As described above, the responder100of the embodiment that receives the interrogation wave Pt from the interrogator200and transmits the response wave Pr to the interrogator200includes the plurality of antennae101receiving the interrogation wave Pt. The responder100of the embodiment includes the reference signal generator112generating the reference signal, the plurality of modems111outputting the quadrature phase amplitudes based on the reception signals output from the antennae101when the interrogation wave Pt is received and the reference signal, and the parallel-time-series signal converters113converting the parallel signals having the quadrature phase amplitudes output from the respective modems111into the time-series signals. Furthermore, the responder100of the embodiment includes the frequency divider106outputting a frequency division signal having a frequency and a phase for detecting the time-series signal, the multiplier107outputting a multiplication signal obtained by multiplying the time-series signal and the frequency division signal, and the beam selector103determining the arrival direction of the interrogation wave Pt based on the multiplication signal.

As described above, the responder100of the embodiment includes the antennae101, the reference signal generator112, the modems111, the parallel-time-series signal converters113, the frequency divider106, the multiplier107, and the beam selector103. Thereby, calculation for suppressing the influence of multipath using fast Fourier transform or the like may be performed using hardware instead of software. Therefore, the responder100of the embodiment can suppress the influence of multipath in a short time. The reference signal is an alternating-current signal having a frequency and a phase of the carrier wave.

In the responder100of the embodiment, at steps S130and S140ofFIG.4, the frequency divider106can change the frequency division ratio of the frequency division signal with time, and the beam selector103can determine the arrival direction of the interrogation wave Pt based on the intensity of the multiplication signal. That is, the responder100of the embodiment can determine the arrival direction of the interrogation wave Pt by serially detecting the multiplication signals having the frequency division ratios changed with time.

On the other hand, in the responder100of the embodiment, at steps S130and S140ofFIG.4, the frequency divider106may output a plurality of frequency division signals having different frequency division ratios from one another in parallel, and the beam selector103may determine the arrival direction of the interrogation wave Pt based on the intensity of the multiplication signals thereof. That is, the responder100of the embodiment can also determine the arrival direction of the interrogation wave Pt by detecting a plurality of multiplication signals in parallel.

As described above, the responder100of the embodiment includes the arrival direction memory unit105and the quadrature phase amplitude memory unit102. The arrival direction memory unit105stores the frequency division ratio as arrival direction information of the interrogation wave Pt output from the beam selector103, and the quadrature phase amplitude memory unit102stores the quadrature phase amplitude. Here, at step S220ofFIG.5, the frequency divider106outputs a response wave frequency division signal (frequency division ratio set by the second frequency divider) having a frequency corresponding to the frequency division ratio as the arrival direction information of the interrogation wave Pt to the multiplier107. At steps S230and S240ofFIG.5, the multiplier107multiplies the response wave frequency division signal (the frequency division ratio set by the second frequency divider) by a response wave time-series signal based on the quadrature phase amplitude stored in the quadrature phase amplitude memory unit102(the output of the quadrature phase amplitude memory unit102), and outputs a response wave multiplication signal to the parallel-time-series signal converter113. At step S250ofFIG.5, the parallel-time-series signal113converter converts the response wave multiplication signal into a response wave parallel signal (a time-series signal converted into a parallel signal) and outputs the signal to the modem111. At steps S260and S270ofFIG.5, the modems111generate the response wave Pr having the response wave quadrature phase amplitude corresponding to the response wave parallel signal (the time-series signal converted into the parallel signal) based on a response wave reference signal (the conjugate LO signal), and the plurality of antennae101transmit the response wave Pr to the interrogator200. According to the configuration, the responder100of the embodiment can preferably transmit the response wave Pr to the interrogator200while suppressing the influence of multipath in a short time.

In the embodiment, the frequency division signal, the time-series signal, the multiplication signal, the parallel signal, the reference signal, and the quadrature phase amplitude for the response wave Pr are the same as or simply inverted from the frequency division signal, the time-series signal, the multiplication signal, the parallel signal, the reference signal, and the quadrature phase amplitude for the interrogation wave Pt. However, the frequency division signal, the time-series signal, the multiplication signal, the parallel signal, the reference signal, and the quadrature phase amplitude for the response wave Pr may be reconstructed by applying correction or the like to those for the interrogation wave Pt.

As described above, the responder100of the108embodiment includes the reception time discriminator discriminating the reception time, at which the interrogation wave Pt is received by the antenna101, based on a predetermined signal component contained in the multiplication signal. The beam selector103can determine the output time of the response wave frequency division signal based on the reception time. Therefore, the reception time of the interrogation wave Pt can be grasped, and the responder100of the embodiment can preferably set, for example, the timing of transmitting the response wave Pr to the interrogator200based on the reception time of the interrogation wave Pt.

Next, one embodiment of a positioning system1using the responder100of the embodiment will be described with reference toFIG.6. In the positioning system1of the embodiment, the interrogator200modulates a signal containing the identification number of the responder100as a target by a predetermined method, generates and transmits an interrogation wave Pt to the responder100.

Similarly to the responder100of the embodiment, the interrogator200of the positioning system1of the embodiment generates a directional wave using an array antenna in which a plurality of antennae101are arranged at predetermined intervals along the receiving surface of the responder100. When the position of the desired responder100is unknown, it is preferable that the interrogator200scans the direction of the directional wave from the interrogator200and holds information on the direction when the response wave Pr is returned.

When the identification number of the own station is detected by the responder100, necessary information is written in advance in a quadrature phase amplitude format in the quadrature phase amplitude memory unit102, and the response wave Pr is transmitted by reading of the information. The operation is performed so that the time from the reception completion time of the interrogation wave Pt to the transmission start time of the response wave Pr is the holding time Th. However, a delay function may be added as necessary.

In the positioning system1of the embodiment, the interrogator200is provided with a distance calculator201calculating a distance from the interrogator200to the responder100, and a position detector202measuring the position of the responder100. The location where the distance calculator201and the position detector202are provided is not particularly limited, and the units may be provided in the responder100, or may be provided in another location than those of the interrogator200and the responder100. When the reception completion of the response wave Pr is determined, the interrogator200calculates a propagation time tpfrom the transmission completion time of the interrogation wave Pt, the reception start time of the response wave Pr, and the holding time th, and calculates a distance from the interrogator200to the responder100. The position of the responder100is calculated from the transmission direction of the interrogation wave Pt and the distance from the interrogator200to the responder100. When both the interrogator200and the responder100are stopped, the propagation time tpof the interrogation wave Pt is equal to the propagation time tpof the response wave Pr.

As described above, the positioning system1of the embodiment includes the above described responder100, interrogator200, distance calculator201calculating the distance from the interrogator200to the responder100, and position detector202measuring the position of the responder100. Here, the interrogator200outputs the interrogation wave Pt containing a specific signal pattern including an identification number, or the like. Further, the distance calculator201calculates the distance from the interrogator200to the responder100based on the difference between the time when the interrogation wave Pt is transmitted from the interrogator200and the time when the response wave Pr transmitted from the responder100is received by the interrogator200and the predetermined holding time th. The position detector202measures the position of the responder100based on the distance.

The positioning system1of the embodiment having the configuration can accurately measure the position of the responder100. In a case where there are a plurality of interrogators200, the position of the responder100can be measured by the plurality of interrogators200even when the interrogators200do not have directionality. In a case where there is one interrogator200, when the interrogator200has directionality, the position of the responder100can be measured. Furthermore, even when there is only one interrogator200and the interrogator200does not have directionality, in a case where the movement direction of the responder100is only one direction, the position of the responder100can be measured.

Next, one embodiment of another positioning system1using the responder100of the embodiment than the positioning system1shown inFIG.6will be described with reference to FIG.7. In the embodiment, an articulated robot10is installed in a center part of the positioning system1, and the responder100is attached to an arm end portion10a. Note that a control device (not shown) is incorporated in the articulated robot10, and the position of the responder100is calculated from the distance to the responder100measured by communication with eight interrogators200(an interrogator200a, an interrogator200b, an interrogator200c, an interrogator200d, an interrogator200e, an interrogator200f, an interrogator200g, and an interrogator200h) in a multipoint positioning manner. In the embodiment, each interrogator200and the control device are electrically coupled by wired communication, but may be coupled by wireless communication.

The interrogator200a, the interrogator200b, the interrogator200c, the interrogator200d, the interrogator200e, the interrogator200f, the interrogator200g, and the interrogator200hare arranged around the articulated robot10, have functions of returning the response waves Pr equivalent to those of the responder100, and can measure the distance between the interrogators200. The distance information between the interrogators200is aggregated in the control device in advance, and thereby, an absolute coordinate system in the positioning system1can be set and the position coordinates of all the interrogators200can be calculated.

Since the interrogator200can also measure the distance from the responder100, the position of the responder100can also be calculated in the absolute coordinate system. Here, the eight interrogators200are provided, however, for measurement of the three-dimensional position of the responder100, unknown variables in three axial directions orthogonal to one another may be obtained. Accordingly, when all the interrogators200are not on the same plane, the position of the responder100can be calculated with at least four interrogators200. When all the interrogators200are provided outside the movement range of the responder100, the position of the responder100can be calculated by the three interrogators200.

In the positioning system1of the embodiment, an appropriate interrogator200can be selected according to the situation of wireless communication. The responder100is attached to a joint portion or the like other than the arm end portion10a, and thereby, the position and the motion of the joint and the arm of the articulated robot10can be measured. In a use scene for a workpiece, the responder100is attached to a tray on which the workpiece is placed, and thereby, the position of the workpiece can be measured. Further, the responder100is controlled to track the transmission direction of the interrogation wave Pt simultaneously with the operation of the respective motors within the articulated robot10and the transport mechanism of the tray based on the information relating to the positions, and thereby, interlocking of the plurality of mechanisms can be controlled.

The positioning in the above described absolute coordinate system is also effective for setting of an initial position necessary before the activation of the articulated robot10, that is, for teaching. In the articulated robot10of related art, an encoder is provided in each joint portion to detect the rotation direction of the joint and the arm and the final coordinates of the arm end portion10aare estimated. When the number of joints increases, measurement errors of the encoders are accumulated, and further, deflection due to their own weights of the arm and the joint portions is caused. Accordingly, a large deviation from the actual position of the arm end portion10amay be caused. In order to improve this, it is necessary to increase rigidity of the arm itself and a holding force of a reducer. On the other hand, the positioning system1of the embodiment is used, and thereby, even when the initial state of each encoder or the like is unknown, for example, the state of the articulated robot10can be grasped by attachment of the responders100to the respective portions of the articulated robot10, transmission of the interrogation wave Pt from the interrogator200, and measurement of the positions of the responders100.

The positioning system1of the embodiment is explained in another expression. As shown inFIG.7, the positioning system1of the embodiment includes a mechanical body12having the articulated robot10as a movable part having the arm, the joint portion, and the like, and a fixed part11onto which the articulated robot10is installed. The interrogators200are provided in the fixed part11, and the responder100is provided in the arm end portion10aof the articulated robot10as the movable part. The positioning system1of the embodiment having the configuration can accurately measure the position of the responder100provided in the movable part. However, not limited to the configuration, but, for example, the responder100may be provided in the fixed part11and the interrogator200may be provided in the movable part according to the apparatus configuration of the mechanical body12or the like.

The present disclosure is not limited to the above described examples and can be implemented in various configurations without departing from the gist of the present disclosure. In order to solve a part or all of the above described problems, or to achieve a part or all of the above described effects, technical features in the embodiments corresponding to the technical features in the respective aspects described in SUMMARY can be replaced or combined as appropriate. Unless the technical features are explained as essential technical features in the specification, the technical features can be deleted as appropriate. For example, in place of the array antenna including the plurality of antennae, one antenna having directionality such as a parabolic antenna may be provided. Note that the present disclosure can be applied to control of an automated guided vehicle in a factory, automated driving, and the like.