JP2006234683A - Positioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position self-position will not become unfixed, when determining the self-position, by using the incoming direction of radio waves from a plurality of radio wave transmitters whose positions are known. <P>SOLUTION: Each radio wave transmitter 1 whose position is known in an absolute coordinate system transmits a radio wave. An antenna device 2 receives radio waves from four or more radio wave transmitters 1, and detects the incoming direction of the radio wave from each radio wave transmitter 1. Each of two circles C1, C2 passing three points of each of two radio wave transmitters 1 and the antenna device 2 is set by using the incoming direction acquired by the antenna device 2 and the positions of the radio wave transmitters 1, and the position excluding the positions of the radio wave transmitters 1 among intersection points between the circles C1, C2 is determined as the position of the antenna device 2. In this case, when three or more radio wave transmitters 1 are included in a determination domain D1 set by a specified width inside and outside one circle C1, a radio wave transmitter 1 outside the determination domain D1 is used as a radio wave transmitter of either circle between the two circles for determining the circle C2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positioning system that estimates the arrival direction of a radio wave transmitted from a radio wave transmitter having a known position and obtains a reception position.

Conventionally, a technique for obtaining the position of a mobile station by receiving radio waves from a mobile station at a plurality of base stations whose positions are known and using the relationship of the arrival directions of radio waves from the mobile stations detected at each base station Is known (see, for example, Patent Document 1). Patent Document 1 also describes that positioning is performed in a mobile station and the positioning result is transmitted to a base station and other mobile stations through communication means. In addition, when the position of the mobile station is determined on the base station side, it is also described that the radio wave for determining the position at the base station and the radio wave for notifying the mobile station of the position are shared. Further, in Patent Document 1, the position measurement result is returned to the base station, and the nearest mobile station is selected or a signal with a small error is selected so that the base station can perform optimal reception or measurement. Or selecting to remove the virtual image.
JP-A-9-119970 (paragraphs 0003-0004, 0035, 0054)

  By the way, when obtaining a position based on the arrival direction of radio waves from a base station in a mobile station, an antenna coordinate system defined as a reference for the arrival direction of radio waves in the mobile station, and an absolute coordinate system defining the position of the base station Is unknown, the mobile station can know only the angle difference between the arrival directions of the radio waves from the two base stations. On the other hand, since the distance between each two base stations is known, one side of a triangle having the two base stations and the mobile station as vertices and the diagonal (vertical angle) of the one side can be known. In other words, if the directions of arrival of radio waves from two base stations are known, one circumference where the mobile station is located can be determined. Therefore, if the arrival directions of the radio waves from the three base stations are known, it is possible to determine the two circumferences where the mobile station is located, and move the position of the intersection excluding the base station among the intersections of both circumferences It can be obtained as the station position. This technique is known as the Cassini solution. A specific calculation method of the Cassini solution will be described later.

  When determining the position of a mobile station using Cassini's solution, it is a precondition that two different circumferences are set depending on the directions of arrival of radio waves from three base stations, but depending on the position of the mobile station May have a third base station located on the circumference determined using the directions of arrival of the two base stations. The problem is that the station position is indefinite.

  The present invention has been made in view of the above reasons, and its purpose is to determine the self-position when determining the self-position using the arrival directions of radio waves from a plurality of radio wave transmitters whose positions are known. An object of the present invention is to provide a positioning system that enables positioning so as not to be indefinite.

  The invention according to claim 1 is an antenna that has four or more radio wave transmitters whose positions in the absolute coordinate system are known and transmits radio waves, and an antenna that receives radio waves from the radio wave transmitters, and is set with the antenna as the origin An antenna device that estimates the direction of arrival of radio waves in the coordinate system from the output of the antenna, and each of two radio wave transmitters and antenna devices using the position of the radio wave transmitter and the direction of arrival of radio waves received by the antenna device. A positioning processing unit that sets two circumferences that pass through a point in one plane and obtains the position of the antenna device in the plane at the intersection of the circumferences excluding the position of the radio wave transmitter. When the processing unit includes three or more radio wave transmitters in the determination area set with a specified width inside and outside the circumference and can receive radio waves from the radio wave transmitters outside the determination area by the antenna device, the antenna device One of the two circumferences for determining the position is set by using a radio wave transmitter in the determination area, and the other is set by using a radio wave transmitter in the determination area and outside the determination area. To do.

  According to this configuration, when another radio wave transmitter is included in the determination region set on the inner and outer circumferences of one circle passing through three points of the two radio wave transmitters and the antenna device, the position is obtained. One of the two circumferences necessary for the setting is set using a radio wave transmitter in the determination area, and the other circumference is set including a radio wave transmitter outside the determination area. Two different circumferences can be set reliably, and the position of the antenna device can be accurately obtained. In order to ensure that two different circumferences can be set, radio wave transmitters must be arranged so that radio waves from four or more radio wave transmitters can be received within the range in which the antenna device moves. is required.

  According to a second aspect of the present invention, in the first aspect of the invention, the positioning processing unit uses a radio wave transmitter used for setting the circumference of a radio wave transmitter whose received electric field strength is within a predetermined range. It is characterized by selecting in order from the smallest.

  According to this configuration, among the radio wave transmitters in which the received electric field strength is within a predetermined range and can be used for obtaining the position of the antenna device, the antenna device is used in order from the smallest received electric field strength. The position of the antenna device is obtained using a radio wave transmitter as far as possible. In other words, if a short-distance radio wave transmitter is used to determine the position of the antenna device, the error when estimating the direction of arrival of the radio wave in the antenna device greatly affects the position obtained by the positioning processing unit. If the device is used, the influence of the error when estimating the direction of arrival of the radio wave in the antenna device on the position obtained by the positioning processing unit can be reduced, and as a result, the error included in the obtained position is reduced. .

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the antenna device includes an arrival direction estimation unit that estimates an arrival direction of a radio wave from an output of the antenna by a plurality of different estimation methods. The method of estimating the direction of arrival of radio waves is defined for each transmitter.

  According to this configuration, by selecting an estimation method according to the environment in which the radio wave transmitter is set, the position can be obtained with high accuracy and introduction is facilitated. For example, if the method of estimating the position by calculation alone is adopted, the range for obtaining the position can be widened because learning is not particularly necessary, but the accuracy of obtaining the position is reduced if there is an influence of multipath. If the method of estimating the position by learning is adopted, the accuracy of obtaining the position does not decrease even if there is an influence of multipath, but it is necessary to learn at multiple points in the range where the position is to be detected. Take it. Therefore, by adopting a method of estimating the position only by calculation in an environment where multipath hardly occurs, and by estimating the position by learning in a relatively narrow area where there are many multipaths, regardless of the installation environment of the radio wave transmitter, The accuracy for obtaining the position can be increased and the introduction can be facilitated.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, there is provided position notifying means for transmitting the position obtained by the positioning processing unit by radio waves from the antenna, and the radio wave transmitter is connected to a computer network. A wireless LAN access point, wherein the position notified from the position notification means to the radio wave transmitter is transferred to a remote terminal using a computer network.

  According to this configuration, the position of the antenna device can be obtained by using the wireless LAN access point also as a radio wave transmitter, and the position obtained by the positioning processing unit can be obtained remotely using a computer network connected to the access point. Therefore, the position of the antenna device can be estimated by the access point used for constructing the wireless LAN.

  According to the configuration of the present invention, when another radio wave transmitter is included in the determination region set on the inner and outer circumferences of one circle passing through the three points of the two radio wave transmitters and the antenna device, the position is determined. One of the two circumferences necessary for the determination is set using a radio wave transmitter in the determination area, and the other circumference is set including a radio wave transmitter outside the determination area. Therefore, there are advantages that two different circumferences can be reliably set and the position of the antenna device can be accurately obtained.

  The positioning system described below is assumed to be used for detecting a self-position in a robot, an automatic guided vehicle, an automatic guided vehicle, a shopping cart, etc., but other devices are within the scope of the technical idea of the present invention. It does not prevent it from being used for.

(Embodiment 1)
In the present embodiment, as shown in FIG. 2, a plurality of radio wave transmitters 1 fixed at known positions in an appropriately set absolute coordinate system O-XYZ, and the arrival directions of radio waves from the radio wave transmitters 1 are shown. The position of the antenna device 2 in the absolute coordinate system O-XYZ is obtained using the respective antenna devices 2 to be detected. The position of the radio wave transmitter 1 may be represented in three dimensions, but the height (Z) is not considered and the position of the radio wave transmitter 1 is represented by a position in a two-dimensional plane (XY plane) along the ground. And Therefore, the position of the antenna device 2 is also represented by a position in a two-dimensional plane along the ground without considering the height. Further, an antenna coordinate system o-xyz is set for the antenna device 2. As described above, since the height (Z) (z) is ignored, the degree of freedom of the antenna coordinate system o-xyz relative to the absolute coordinate system O-XYZ depends on the position in the XY plane and the rotation around the z axis. And 3 degrees of freedom.

  The antenna device 2 includes an electronically controlled array antenna (electronic scanning antenna) capable of electronically controlling reception directivity as the antenna 21. As an array antenna of this type, as shown in FIG. 3, in addition to an active array antenna in which a plurality of antenna elements 21a that are monopoles (four in the illustrated example) are arranged, as shown in FIG. Also known is a parasite load switching antenna (so-called ESPER antenna) in which a plurality of (six in the illustrated example) non-excitation elements (parasite elements) 21b are arranged at equal angular intervals around a certain excitation element (antenna element) 21a. Yes.

  As shown in FIG. 3, the active array antenna has a configuration in which the antenna elements 21a are arranged on the circumference, and the arrival direction of the radio wave is estimated using the reception correlation of the radio wave received by each antenna element 21a. When the antenna 21 having this configuration is used, the arrival direction of the radio wave can be estimated without changing the reception condition, and thus the arrival direction of the radio wave can be obtained in a short time. That is, even when the relative position between the radio wave transmitter 1 and the antenna device 2 fluctuates in a relatively short time, the arrival direction of the radio wave can be accurately obtained. However, since a plurality of antenna elements 21a are required, the circuit configuration for amplifying the output of each antenna element 21a and detecting the phase difference is somewhat complicated, and the amount of calculation for obtaining the position is comparative. Increase. Since the active array antenna determines the direction of arrival of radio waves from the reception correlation of each antenna element 21a, it does not directly control the reception directivity, but extracting the phase difference controls the reception directivity. Is equivalent to Therefore, the active array antenna can also be said to be an electronic scanning antenna.

  On the other hand, the parasite load switching type antenna has a configuration in which the parasite elements 21b are arranged on the circumference centering on the antenna element 21a, as shown in FIG. 4, and the reception of the reception by changing the reactance of the parasite elements 21b. The direction of arrival of radio waves is estimated using changes in reception intensity and phase when reception is performed under reception conditions having different directivities. That is, since the number of the antenna elements 21a is one, the circuit configuration is simplified and the antenna element 21a can be provided at low cost. However, since it is necessary to change the reception condition by changing the impedance of the parasitic element 21b, it takes time to obtain the arrival direction of the radio wave. As a result, when the relative position between the radio wave transmitter 1 and the antenna device 2 changes in a relatively short time, the relative position changes while changing the reception condition, and the obtained arrival direction error becomes large. .

  As described above, the advantages and disadvantages of the active array antenna and the parasite load switching antenna conflict, but they can be used appropriately according to the purpose. A configuration example in the case of using an active array antenna is shown in FIG. 3, and a configuration example in the case of using a parasite load switching antenna is shown in FIG. The configuration example of FIG. 3 is different from the configuration example of FIG. 4 in that a reactance switching unit 26 that switches the reactance of the parasitic element 21b in the configuration example of FIG. 4 is provided, and the specific configuration of each circuit is different. Since the basic operation of each circuit is common, the configuration example of FIG. 3 will be mainly described, and the configuration example of FIG. 4 will be described as necessary.

  In addition to the antenna 21, the antenna device 2 includes a reception signal processing unit 22 that separates the signal of each radio wave transmitter 1 from the output of the antenna 21, and an arrival direction estimation that estimates the arrival direction of the radio wave for each radio wave transmitter 1. Unit 23 and configured to output the direction of arrival of radio waves from each radio wave transmitter 1.

  That is, the output of the antenna device 2 is first input to the received signal processing unit 22 where amplification and frequency conversion are performed, and the digital signal is converted by the A / D converter. The radio wave from each radio wave transmitter 1 includes identifiable information, and the received signal processing unit 22 can identify which radio wave transmitter 1 is the radio wave. Various techniques for such identification are known, but in the present embodiment, a method of varying the output frequency for each radio wave transmitter 1 is adopted. However, since it is inconvenient if the output frequencies of the plurality of radio wave transmitters 1 are different from each other because the occupied frequency band becomes wide, it is difficult to identify each radio wave transmitter 1 by using time division multiplexing (TDD). A method of intermittently transmitting a signal sequence including a code may be employed. Moreover, you may employ | adopt the multiplexing system (FDD / TDD) which used frequency and time together. In any case, the reception signal processing unit 22 identifies the signal from each radio wave transmitter 1, separates the signal for each radio wave transmitter 1, and delivers it to the arrival direction estimation unit 23. The arrival direction estimation unit 23 estimates the arrival direction of radio waves for each radio wave transmitter 1 by a method described later.

  By the way, the arrival direction of the radio wave detected by the arrival direction estimation unit 23 is delivered to the positioning processing unit 24. The positioning processing unit 24 calculates the position of the antenna device 2 (antenna 21) using the known position of each radio wave transmitter 1 stored in the position storage unit 25. The arrival direction estimation unit 23 and the positioning processing unit 24 are configured by an integrated circuit including a DSP (digital signal processor), and a rewritable semiconductor memory is used for the position storage unit 25. Hereinafter, the operation principle of the positioning processing unit 24 will be described.

  In the antenna coordinate system o-xyz described above, the origin (o) is set to the antenna 21 provided in the antenna device 2, and the object to be obtained by the device shown in FIG. 3 is the XY plane of the absolute coordinate system O-XYZ. It becomes the coordinates (X, Y) of the position of the origin (o). Information that can be used to obtain the coordinates (X, Y) of the origin (o) is the coordinates of three or more radio wave transmitters 1 and the arrival directions of radio waves from the radio wave transmitters 1. However, since the rotation of the antenna coordinate system o-xyz around the z-axis, that is, the angle formed by the X-axis and the x-axis is unknown, the azimuth in the absolute coordinate system O-XYZ cannot be obtained for the radio wave arrival direction. The angle information that can be obtained with respect to the absolute coordinate system O-XYZ is an angle difference between the arrival directions of the radio waves from the two radio wave transmitters 1. On the other hand, since the position of the radio wave transmitter 1 in the absolute coordinate system O-XYZ is known, if the angle difference between the arrival directions of the radio waves from the two radio wave transmitters 1 is known, the two radio wave transmitters 1 are One circumference can be set with the connecting line segment as a string and the angular difference between the arrival directions of the radio waves from the two radio wave transmitters 1 as the circumference angle stretched on the string. This circumference is a circumference that passes through the two radio wave transmitters 1 and the origin (o) of the antenna device 2.

  That is, if the arrival directions in the antenna coordinate system o-xyz are detected for the radio waves from the three radio wave transmitters 1, normally two circles can be set, and the antenna device is at the intersection of both circles. It can be estimated that the origin of 2 is located. However, although there are two intersections of two circumferences, one intersection is not the position of the antenna device 2 but the position of the radio wave transmitter 1 shared for setting the two circumferences. In other words, the position of the antenna device 2 is not the position of the radio wave transmitter 1 among the two intersections of the two circumferences.

  The positioning calculation unit 24 shown in FIG. 3 performs a calculation to obtain the coordinates (X, Y) of the position of the origin (o) of the antenna device 2 in the absolute coordinate system O-XYZ based on the above-described principle. This operation is known as Cassini's solution. Since the Cassini solution is known, only the arithmetic expression is shown.

  Assume that the coordinates of the installation positions of the three radio wave transmitters 1 are already known. Further, it is assumed that the arrival directions of radio waves from each radio wave transmitter 1 in the antenna coordinate system o-xyz are also known. According to FIG. 5, the positions of the three radio wave transmitters 1 are represented by points P1 to P3, respectively, and the coordinates of the points P1 to P3 on the XY plane are (X1, Y1) (X2, Y2) (X3, Y3), respectively. . Further, the angle difference (circumferential angle) of the direction of arrival of the radio wave received from the radio wave transmitter 1 at the points P1 and P2 is A, and the direction of arrival of the radio wave received from the radio wave transmitter 1 at the points P2 and P3 is indicated. The angle difference (circumferential angle) is B.

  When the circumference of the circumference angle A that stretches around this string with the line segment P1P2 as the string and the circumference of the circumference angle B that stretches around this string with the line segment P2P3 as the string are set, the intersections P and P2 of both circumferences The position that is not the point P2 is the position of the antenna device 2. That is, the coordinates (X, Y) are obtained from the coordinates (X1, Y1) (X2, Y2) (X3, Y3) and the angle differences A, B. In order to obtain the coordinates (X, Y) of the intersection point P, an auxiliary line orthogonal to the line segment P2P and passing through the point P is set. When the intersections between the auxiliary line and each circumference are Pc and Pd, the line segments P2Pc and P2Pd are the diameters of the respective circles. Here, the coordinates of the points Pc and Pd are respectively (Xc, Yc) (Xd, Yd). By using the above relationship, the coordinates (X, Y) can be expressed as in Equation 1.

Further, by using the obtained coordinates (X, Y), with respect to one radio wave transmitter 1, the arrival direction φ1 of the radio wave in the antenna coordinate system o-xyz and the position of the radio wave transmitter 1 in the absolute coordinate system O-XYZ. From the coordinates (X1, Y1) of the antenna 21, the rotation angle θ around the Z axis with respect to the absolute coordinate system O-XYZ of the antenna coordinate system o-xyz (see FIG. 2), in other words, the absolute coordinate system O- The orientation in XYZ can be obtained.
θ = tan ⁻¹ {(Y1−Y) / (X1−X)} − φ1
As described above, by using the arrival directions of the radio waves from the three radio wave transmitters 1 and the coordinates (X1, Y1) (X2, Y2) (X3, Y3) of each radio wave transmitter 1, the antenna 21 The position coordinates (X, Y) and the orientation of the antenna 21 can be known.

  Incidentally, in order to calculate the position of the antenna 21 in the positioning processing unit 24, it is necessary to estimate the arrival direction of the radio wave from each radio wave transmitter 1 in the arrival direction estimation unit 23 using the output of the antenna 21. In the following, the operation from the output of the antenna 21 until the arrival direction estimation unit 23 estimates the arrival direction of the radio wave from the radio wave transmitter 1 will be described.

  When an active array antenna is used, an amplifier 22a, a frequency converter 22b, and an A / D converter 22c are provided for each antenna element 21a in order to obtain a difference in reception time between the plurality of antenna elements 21a. The frequency converter 22b has a variable local frequency and changes the reception frequency by changing the local frequency. For example, if there are four antenna elements 21a, four systems of amplifiers 22a, frequency converters 22b, and A / D converters 22c are required. At the time of A / D conversion, a sampling period is set such that a difference in reception time at each antenna element 21a can be detected. A sampling period is provided for each frequency of each radio wave transmitter 1.

  In the present embodiment, it is assumed that the position of the antenna 21 is obtained using radio waves from up to four radio wave transmitters 1, and the sampling period in the reception signal processing unit 22 is provided four times. In short, the reception frequency is switched four times in one calculation of the arrival direction, and the radio waves from the four radio wave transmitters 1 are extracted. Here, when five or more radio wave transmitters 1 are provided, the reception frequency is switched in five steps or more. However, a range of the received electric field strength is determined in advance, and radio waves are received within the range. If four radio wave transmitters 1 that can be used are used in the order of reception, radio waves from the four radio wave transmitters 1 can be extracted.

In one sampling period, about 100 points are sampled and delivered to the arrival direction estimation unit 23 after quantization. Since the arrival direction estimation unit 23 obtains four types of reception outputs x _i (t) (i = 1, 2, 3, 4) at time t for each frequency, this reception output x _i (t) is used as a component. A correlation matrix Rxx is generated using the received vector [x (t)]. The received vector and the correlation matrix are different in the number of components, but have the same shape as the case where a parasite load switching antenna described later is used.

On the other hand, when a parasite load switching type antenna is used, as shown in FIG. 4, the impedance of each parasite element 21b is sequentially changed by the reactance switching unit 26, and the output of the antenna element 21a obtained each time the impedance is switched is determined as the arrival direction. This is given to the estimation unit 23. When using a parasite load switching antenna, it is necessary to provide an amplifier 22a, a frequency converter 22b, and an A / D converter 22c as in the case of using an active array antenna, but there is only one antenna element 21a. Only one system is required. The impedance of the parasitic element 21b is switched depending on whether it is grounded or not. Here, assuming a parasite load switching antenna having six parasite elements 21b, the antenna element 21a obtains six types of received outputs x _i (t) (i = 1, 2,..., 6) at time t. Therefore, the correlation matrix Rxx shown in Equation 3 is generated using the reception vector [x (t)] shown in Equation 2 having the reception output x _i as a component. Here, each reception output x _i (t) has a real part and an imaginary part. [X] indicates that x is a vector. Note that the reception output x _i (t), which is a component of the reception vector [x (t)], is not obtained at the same time, but is considered to be obtained at the same time because the switching cycle is short. .

However, E [[x]] represents an ensemble average.

  A technique called “super-decomposition method” is known as a method for evaluating the correlation matrix Rxx to determine the direction of arrival of radio waves in the antenna coordinate system o-xyz. If the “super-decomposition method” is employed, the antenna 21 The accuracy of detecting the direction of arrival of radio waves is significantly higher (error is 1 to 2 degrees) than the method of searching for the direction in which the electric field strength is greatest by changing the directivity of the signal (error is several tens of degrees). As the “super-decomposition method”, a null steer interferometer method, a MUSIC method, and a neural network method using a learned neural network are known. Each method has its advantages and disadvantages. First, each method will be briefly described.

  In the interferometer method, the arrival direction is obtained using null steer. In the interferometer method, an evaluation function is obtained using a table in which a vector value called a steering vector obtained from the output of the antenna 21 is associated with the arrival direction of radio waves. The steering vector is obtained based on an actual measurement value or a theoretical value, and means a reception output x (t) when the signal vector [s (t)] arrives from the arrival direction φ with respect to the reception antenna 21. .

Thus, using the above-described correlation matrix Rxx obtained from the received vector [x (t)], a plurality of steering vectors [a (φ)] obtained in advance for the known arrival direction (φ) and stored in the table. _Is used to obtain the evaluation function P _intr (φ) shown in _Equation 4. The denominator of the evaluation function P _intr (φ) corresponds to the distance between each component of the correlation matrix Rxx and the steering vector [a (φ)] stored in the table, and the evaluation function P _intr (φ) is a radio wave transmission. It has a distribution with respect to the direction of arrival φ of the radio wave from the vessel 1. In this distribution, the arrival direction φ corresponding to the steering vector [a (φ)] that maximizes the evaluation function P _intr (φ) can be regarded as the arrival direction φ of the radio wave from the radio wave transmitter 1.

MUSIC (Mu ltiple Si gnal Classification) method is a method of using the eigenvalues and eigenvectors of the correlation matrix Rxx, not described in detail because it is well known technology, a value of MUSIC spectrum that the direction of arrival parameters from the correlation matrix Rxx This is a method for obtaining the direction of arrival of radio waves from the radio wave transmitter 1 by evaluating the received electric field strength with respect to the direction of arrival where the MUSIC spectrum is maximized.

Further, the neural network method generates a vector [b] having a component shown in Expression 5 among the components of the correlation matrix Rxx obtained from the received vector x (t), and normalizes the vector [b]. The vector [b] has a component in which a real part Re (r _ij ) and an imaginary part Im (r _ij ) are arranged in order with respect to the component on the right side of the main diagonal of the correlation matrix Rxx.

The neural network is an RBF neural network having an input layer, an intermediate layer, and an output layer, and the neurons in the intermediate layer of the neural network are set as shown in Equation 6.

Since the value to be obtained by the neural network is the arrival direction φ of the radio wave shown in FIG. 2, for example, the neural network is configured to obtain one type of output value f ([x]), and f ( With [x]) = φ, the neural network performs learning with teaching using the received vector [x (t)] obtained when the antenna 21 is positioned at a plurality of teaching points where the arrival direction φ is known. By learning with teaching, learning of parameters x _j , σ _j ² , and ω _j (where σ _j ² is variance and ω _i is a weighting factor) in Equation 7 is performed, and an arrival direction φ at a location other than the teaching point is obtained. Is possible. When the neural network is trained, regardless of whether the radio wave received by the antenna 21 is a direct wave or an indirect wave from the radio wave transmitter 1, the learned parameter x _j , σ _j ² , ω _j has the arrival direction φ of the radio wave. Therefore, the direction of arrival φ can be estimated if the indirect wave is stationary even in an environment where the indirect wave exists and does not change with time in the region where the automatic guided vehicle travels.

  By the way, when detecting the direction of arrival of radio waves, if the antenna 21 receives only the direct wave from the radio wave transmitter 1 and there is no noise, it can be received by any of the three methods described above. It is possible to accurately determine the direction. However, in an environment where there are many buildings even when used indoors or outdoors, multipath is likely to occur in the route from the radio wave transmitter 1 to the antenna 21. When multipath occurs, it is difficult to estimate the direction of arrival by the interferometer method. In the MUSIC method, the arrival direction of the radio wave is estimated from the maximum value of the MUSIC spectrum using the wave number estimation method. Therefore, if the environment can receive a direct wave by moving average even if multipath occurs, the signal from the radio wave transmitter 1 is used. The arrival direction of radio waves can be obtained. However, even if the MUSIC method is used, direct waves cannot be received, and if only multipath radio waves can be received, the direction of arrival of radio waves from the radio wave transmitter 1 cannot be estimated. On the other hand, in the neural network method, since the arrival direction of the radio wave (the direction of the straight line connecting the radio wave transmitter 1 and the antenna 21) and the environment are taught in advance, it is possible to receive a direct wave. Even if it is not possible, the direction of arrival of radio waves can be specified.

  However, if the neural network method is used, the error in the direction of arrival obtained increases at locations other than the teaching point, so the number of teaching points must be increased in order to improve the accuracy of obtaining the direction of arrival. That is, if the direction of arrival is detected by the neural network method, it takes time to actually operate. On the other hand, since the interferometer method and the MUSIC method are only operations, there is no need to teach them and the time required for actual operation is short. Regarding the calculation time, the neural network method is the shortest, and the calculation time becomes longer in the order of the interferometer method and the MUSIC method.

  The arrival direction estimation unit 23 prepares these three types of estimation methods, and automatically selects an estimation method according to which radio wave transmitter 1 is processing the radio wave. That is, each of the radio wave transmitters 1 encodes information indicating which of the three types of estimation methods to use and transmits it by radio waves. The reception signal processing unit 22 extracts the code from the output of the antenna 21. The arrival direction estimation unit 23 is handed over. Therefore, the arrival direction estimation unit 23 estimates the arrival direction of radio waves using an estimation method selected according to the code given from the reception signal processing unit 22. By designating the direction of arrival estimation method from the radio wave transmitter 1 in this way, it becomes possible to adopt an optimal estimation method according to the environment in which the radio wave transmitter 1 is installed. In addition, since the radio waves from a plurality of radio wave transmitters 1 are simultaneously received, if the estimation method instructed from the radio wave transmitters 1 that are simultaneously receiving the radio waves is different, the arrival direction estimation unit 23 transmits each radio wave. The direction of arrival estimation method is switched for each unit 1.

  By the way, as described above, in order to obtain the position of the antenna 21, the radio waves from the three radio wave transmitters 1 are simultaneously received, and two of the three radio wave transmitters 1 are arranged on the circumference. It is necessary to set the two circumferences that are located. However, depending on the positional relationship between the radio wave transmitter 1 and the antenna 21, it is considered that the three radio wave transmitters 1 and the antennas 21 may be located on one circumference. In this case, since the two circumferences cannot be set, the position of the antenna 21 cannot be obtained.

  Therefore, in this embodiment, the radio wave transmitter 1 is arranged so that radio waves from four or more radio wave transmitters 1 can be received at any position within the moving range of the antenna 21. In addition, as shown in FIG. 1, a judgment area D1 (shaded portion) is set with a predetermined width inside and outside the circumference C1 set by using two radio wave transmitters 1, and the radio wave transmission in which the circumference C1 is set. It is determined whether or not the radio wave transmitter 1 excluding the device 1 is included in the determination area D1. When the radio wave transmitter 1 except the radio wave transmitter 1 having the circumference C1 is included in the determination area D1, the radio wave transmitter 1 not included in the determination area D1 and two radio wave transmissions having the circumference C1 set Two circumferences C1 and C2 are set using the container 1. If the radio wave transmitter 1 is appropriately disposed, the two circumferences C1 and C2 can be surely set by the above-described procedure, and the position of the antenna 21 can be obtained. That is, even if the three radio wave transmitters 1 and the antenna 21 are located on almost one circumference and these radio wave transmitters 1 cannot set two circumferences, the fourth radio wave By using the transmitter 1, it is possible to determine the position of the antenna 21 by setting two circumferences.

  In addition, by selecting three radio wave transmitters 1 from four radio wave transmitters 1, four coordinates (X, Y) of the antenna 21 are obtained, and if there is an abnormal value among the obtained results, there is an error. The value may be excluded and the remaining average value may be used as coordinates (X, Y).

  As described above, radio waves from four or more radio wave transmitters 1 can be simultaneously received by the antenna 21, so that the determination region D <b> 1 defined on the circumference C <b> 1 set by the two radio wave transmitters 1 as described above. When no other radio wave transmitter 1 is located, it is possible to set three or more circumferences. On the other hand, the angular error related to the arrival direction is almost constant regardless of the distance between the radio wave transmitter 1 and the antenna 21, but the ratio of the error related to the distance is larger at the short distance. That is, the error included in the coordinates (X, Y) obtained by Equation 1 increases as the distance from the antenna 21 to the radio wave transmitter 1 is shorter. That is, it is desirable to obtain the coordinates (X, Y) using the circumferences C1 and C2 using the radio transmitter 1 as far as possible within the usable range.

  Usually, since the output of each radio wave transmitter 1 is set equal, it can be said that the distance from the radio wave transmitter 1 is reflected in the received electric field intensity at the antenna 21. Therefore, the received signal processing unit 21 passes the information on the strength of the received signal through the arrival direction estimating unit 23 to the positioning processing unit 24, and the positioning processing unit 24 includes four radio wave transmitters 1 that can receive radio waves. If it is not included in D1, the three radio wave transmitters 1 are selected in ascending order of received signal strength, and the coordinates (X, Y) of the antenna 21 are obtained using these radio wave transmitters 1. Such processing can improve the accuracy of the positioning result as much as possible.

  By the way, in the above example, the radio wave transmitter 1 has only a function of transmitting radio waves, and the antenna device 2 has only a function of receiving radio waves, but between the radio wave transmitter 1 and the antenna device 2, Radio waves can be transmitted and received, and the calculation result in the positioning processing unit 24 may be returned to the radio wave transmitter 1 as indicated by a broken line in FIG. In this case, position notification means (not shown) for transmitting the position obtained by the positioning processing unit 24 from the antenna 21 by radio waves is provided. Further, the radio wave transmitter 1 is connected to the computer network NT, and the calculation result of the positioning processing unit 24 can be transferred to the remote terminal 3 using the computer network NT. That is, it becomes possible to know the positioning result of the position and orientation of the antenna 21 obtained by the positioning processing unit 24 by the terminal 3 arranged at a distant place, and the positioning result can be used for various uses. If a radio LAN access point or a mobile phone base station is used as the radio wave transmitter 1, it is possible to perform positioning using the existing radio wave transmitter 1, and the positioning result is distant. Can be transferred to.

  As indicated by a one-dot chain line in FIG. 3, a display device 27 for displaying the received signal strength may be added to the received signal processing unit 22. The display device 27 includes a plurality of (four in the illustrated example) indicator lamps 27 a that indicate whether or not the received signal intensity is greater than or equal to a predetermined value for each radio wave transmitter 1, and each radio wave stored in the position storage unit 25. A display unit 27b for displaying the coordinates of each transmitter 1; That is, the reception signal processing unit 22 identifies the radio wave transmitter 1 using the frequency of the radio wave from each radio wave transmitter 1 and extracts and displays the coordinates of each radio wave transmitter 1 stored in the position storage unit 25. The information is displayed on the display unit 27b of the device 27.

  When the display device 27 is provided in this manner, when any of the four radio wave transmitters 1 is not transmitting radio waves due to a failure or the like, the lighting state of the indicator lamp 27a (when the electric field strength is greater than or equal to a predetermined value). It is possible to easily know at which position the radio wave transmitter 1 is malfunctioning. Instead of identifying each radio wave transmitter 1 by the frequency of the radio wave, if the radio wave from each radio wave transmitter 1 includes an identification code, the radio wave transmitter 1 may be identified by the identification code. . Moreover, when transmission / reception is enabled between the radio wave transmitter 1 and the antenna device 2 as described above, the content of the display device 27 may be transmitted to the remote terminal 3.

(Embodiment 2)
The first embodiment assumes a case where the radio wave transmitter 1 is fixed at a fixed position, but each radio wave transmitter 1 detects its own position in the absolute coordinate system O-XYZ by a technique such as GPS. If it is the structure to perform, even if it is the structure to which the electromagnetic wave transmitter 1 moves, the position and direction of the antenna 21 can be calculated | required. In this case, since the position of the radio wave transmitter 1 is updated as time passes, it is not necessary to provide the position storage unit 25. However, the position of the self position of the radio wave transmitter 1 is determined by the radio wave transmitted from the radio wave transmitter 1. It is necessary to notify the unit 24. That is, the reception signal processing unit 22 separates the information on the position of the radio wave transmitter 1 from the information included in the radio wave received from the antenna 21 and provides the position processing unit 24 with the information.

  By adopting the configuration of the present embodiment, the position and orientation of the antenna 21 can be measured even when the radio wave transmitter 1 is mounted on a moving body such as an automobile. Other configurations and operations are the same as those of the first embodiment.

It is a principle explanatory view of the present invention. It is principle explanatory drawing same as the above. It is a block diagram same as the above. It is a block diagram of the other structural example same as the above. It is principle explanatory drawing which shows how to obtain | require a position in the same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio wave transmitter 2 Antenna apparatus 3 Terminal 21 Antenna 23 Arrival direction estimation part 24 Positioning processing part C1, C2 Circumference D1 Determination area NT Computer network

Claims (4)

  Direction of arrival of radio waves in an antenna coordinate system that has four or more radio wave transmitters whose positions in the absolute coordinate system are known and transmits radio waves, and an antenna that receives radio waves from the radio wave transmitters and is set with the antenna as the origin The circumference passing through the three points of each of the two radio wave transmitters and the antenna device using the antenna device for estimating the output from the antenna output, the position of the radio wave transmitter and the arrival direction of the radio wave received by the antenna device. A positioning processing unit that sets two positions in one plane and excludes the position of the radio wave transmitter from the intersections of the circumferences as the position of the antenna device in the plane, and the positioning processing unit To determine the position of the antenna device when the antenna device can receive radio waves from radio wave transmitters outside the determination region that include three or more radio wave transmitters in the determination region set with a prescribed width inside and outside Positioning system one of the two circumferential other set using the radio transmitters in the determination area, characterized in that the set using the radio transmitters of the determination area outside the the determination area.   2. The positioning processing unit selects a radio wave transmitter used for setting the circumference in order from a radio wave transmitter having a received electric field strength within a predetermined range in ascending order of the received electric field strength. The described positioning system.   The antenna device includes an arrival direction estimation unit that estimates an arrival direction of a radio wave from a plurality of types of estimation methods using an antenna output, and a method for estimating the arrival direction of the radio wave is defined for each radio wave transmitter. The positioning system according to claim 1 or 2, characterized in that   Position notification means for transmitting the position obtained by the positioning processing unit by radio waves from the antenna, and the radio wave transmitter is a wireless LAN access point connected to a computer network, from the position notification means to the radio wave transmitter. 4. The positioning system according to claim 1, wherein the notified position is transferred to a remote terminal using a computer network.

Images