Patent Publication Number: US-2022236397-A1

Title: Position estimation system, information processing device, non-transitory computer-readable storage medium, and information processing method

Description:
TECHNICAL FIELD 
     The present invention relates to a position estimation system, an information processing device, a program, and an information processing method. 
     BACKGROUND ART 
     Conventionally, as a position estimation system that uses wireless communication, it is known that there has been a system that uses a wireless transmitting device and a wireless receiving device to estimate the position of a target. 
     For example, the position estimation system described in Patent Reference  1  receives a wireless communication signal transmitted from a wireless transmitting device with a wireless receiving device, calculates a reception intensity pattern or an occurrence probability of the reception intensity pattern of a direct wave from the wireless transmitting device and a reflected wave reflected by a target, and records the reception intensity pattern or the occurrence probability at a specific position in advance as a database. When performing a position estimation, this system refers to the database to estimate the position of the target from the position corresponding to the most similar reception intensity pattern or occurrence probability. 
     PRIOR ART REFERENCE 
     Patent Reference 
     Patent Reference 1: Japanese Patent No. 4868169 (pages 11 to 14 and FIG. 1) 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     The conventional position estimation system assumes a case where only one target is to be estimated. Therefore, for example, when there is a person other than the person to be the target of the position estimation, it is difficult to estimate the position. 
     Specifically, when two persons A and B are in one room and the position in the room of one of them is to be estimated, although the reflected wave from the person A becomes constant if the person A stays at the same position in the room, the intensity of the reflected wave from the person B varies depending on the position of the person B in the room. Therefore, the reception intensity pattern received by the wireless receiving device varies greatly depending on the position of the person B. 
     In order to estimate the position of the person A from the reception intensity pattern, in conventional position estimation system, it is necessary to register the reception intensity patterns or the occurrence probabilities for various cases for the person B being anywhere in the room in advance, which enlarges the database. 
     Furthermore, when there are two or more persons, or when a non-human target that reflects electromagnetic waves moves around, it is difficult to register various possible cases in the database, so that the conventional position estimation system cannot estimate the accurate position. 
     Accordingly, it is an object of one or more aspects of the present invention to estimate, even when there are multiple persons, the position of any one of them. 
     Means of Solving the Problem 
     A position estimation system according to an aspect of the present invention includes: an information processing device; a transmitting device to transmit a wireless signal; a receiving device to detect a reception intensity of the wireless signal and to sequentially output reception intensity information indicating the detected reception intensity to the information processing device; and a person detecting device to sequentially output predetermined person detection information to the information processing device when a person existing within a predetermined range is detected, wherein the information processing device comprises: a reception intensity information input unit to receive input of the reception intensity information; a signal pattern information generating unit to generate signal pattern information indicating a signal pattern indicating a transition of the reception intensity in a predetermined period by using the reception intensity indicated by the reception intensity information input in the predetermined period; a person detection information input unit to receive input of the person detection information; and a position estimation unit to estimate, when the person detection information input unit receives input of the person detection information within the predetermined period the position of the person detecting device in the signal pattern indicated by the generated signal pattern information to be the position where a person exists. 
     An information processing device according to an aspect of the present invention includes: a reception intensity information input unit to receive, from a receiving device to detect a reception intensity of a wireless signal transmitted from a transmitting device and to sequentially output reception intensity information indicating the detected reception intensity, input of the reception intensity information; a signal pattern information generating unit to generate signal pattern information indicating a signal pattern indicating a transition of the reception intensity in a predetermined period by using the reception intensity indicated by the reception intensity information input in the predetermined period; a person detection information input unit to receive input of the person detection information from a person detecting device, the person detecting device detecting that a person exists within a predetermined range and sequentially outputting predetermined person detection information to the information processing device; and a position estimation unit to estimate, when the person detection information input unit receives input of the person detection information within the predetermined period, to be the position where a person exists, the position of the person detecting device in the signal pattern indicated by the generated signal pattern information. 
     A program according to an aspect of the present invention causes a computer to function as: a reception intensity information input unit to receive, from a receiving device to detect a reception intensity of a wireless signal transmitted from a transmitting device and to sequentially output reception intensity information indicating the detected reception intensity, input of the reception intensity information; a signal pattern information generating unit to generate signal pattern information indicating a signal pattern indicating a transition of the reception intensity in a predetermined period by using the reception intensity indicated by the reception intensity information input in the predetermined period; a person detection information input unit to receive input of the person detection information from a person detecting device, the person detecting device detecting that a person exists within a predetermined range and sequentially outputting predetermined person detection information to the information processing device; and a position estimation unit to estimate, when the person detection information input unit receives input of the person detection information within the predetermined period, to be the position where a person exists, the position of the person detecting device in the signal pattern indicated by the generated signal pattern information. 
     An information processing method according to an aspect of the present invention includes: receiving, from a receiving device to detect a reception intensity of a wireless signal transmitted from a transmitting device and to sequentially output reception intensity information indicating the detected reception intensity, input of the reception intensity information; generating signal pattern information indicating a signal pattern indicating a transition of the reception intensity in a predetermined period by using the reception intensity indicated by the reception intensity information input in the predetermined period; receiving input of the person detection information from a person detecting device, the person detecting device detecting that a person exists within a predetermined range and sequentially outputting predetermined person detection information to the information processing device; and estimating, when the person detection information input unit receives input of the person detection information within the predetermined period, to be the position where a person exists, the position of the person detecting device in the signal pattern indicated by the generated signal pattern information. 
     Effects of the Invention 
     According to one or more aspects of the present invention, even when there are multiple persons, the position of any one of them can be estimated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically illustrating a configuration of a position estimation system according to an embodiment. 
         FIG. 2  is a block diagram schematically illustrating a configuration of a controlling device. 
         FIGS. 3A and 3B  are block diagrams illustrating an example of a hardware configuration. 
         FIG. 4  is a flow chart illustrating an operation of the controlling device. 
         FIG. 5  is a schematic diagram illustrating a first example in which a plurality of persons exist in a room. 
         FIG. 6  is a schematic diagram illustrating a second example in which a plurality of persons exist in a room. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
       FIG. 1  is a block diagram schematically illustrating a configuration of a position estimation system  100  according to an embodiment. 
     The position estimation system  100  includes a transmitting device  110 , a receiving device  120 , a person detecting device  130 , and a controlling device  140  as an information processing device. 
     The transmitting device  110 , the receiving device  120 , and the person detecting device  130  are connected to the controlling device  140 . 
     The transmitting device  110 , the receiving device  120 , and the person detecting device  130  are arranged with respect to a room  300 , so that the position of a detection target in the room  300  as the space for performing detection can be detected. Specifically, as shown in  FIG. 1 , the transmitting device  110  and the receiving device  120  are disposed within the room  300 , the person detecting device  130  is disposed at the entrance of the room  300 , and the controlling device  140  is disposed outside the room  300 . 
     The arrangement of these devices is not limited to the example shown in  FIG. 1 , and for example, at least one of the transmitting device  110  and the receiving device  120  may be disposed outside the room  300 , or the person detecting device  130  may be disposed in the room  300 . The controlling device  140  may also be disposed in the room  300 . 
     Further, a plurality of transmitting devices  110 , a plurality of receiving devices  120 , or a plurality of person detecting devices  130  may be provided. 
     It is assumed that there are a person  301  and a person  302  as targets of position detection in the room  300 , but the target of detection is not limited to a person but may be an object, which is not a person, or the objects to be detected are not limited to two targets as long as they are one or more targets. 
     The transmitting device  110  transmits a wireless signal. 
     The receiving device  120  receives the wireless signal transmitted from the transmitting device  110 . The receiving device  120  detects reception intensity of the received wireless signal and sequentially outputs reception intensity information indicating the detected reception intensity to the controlling device  140 . Alternatively, the controlling device  140  may convert the reception intensity of the wireless signal detected by the receiving device  120  into reception intensity information. 
     Although not shown, in a case where a plurality of transmitting devices  110  are provided in the room  300  and wireless signals transmitted from each of the plurality of transmitting devices  110  can be distinguished by frequency, the receiving device  120  provides reception intensity information indicating the reception intensity for each frequency to the controlling device  140 . 
     The wireless communication between the transmitting device  110  and the receiving device  120  may be, for example, wireless LAN (Local Area Network) communication called Wi-Fi® or peer-to-peer wireless communication called Bluetooth®. 
     By using wireless communication such as Wi-Fi or Bluetooth, the transmitting device  110  and the receiving device  120  can be implemented at a low cost without the need for dedicated wireless communication components. Further, the position estimation system  100  can be implemented by using a general device without preparing a device dedicated to position estimation. 
     In the position estimation by the position estimation system  100 , in addition to the purpose of position estimation, a wireless signal transmitted from the transmitting device  110  may be used for the purpose of transmitting necessary information or a program, or a wireless signal transmitted from the transmitting device  110  may be used exclusively for position estimation during a period when communication is not used for the purpose of transmitting necessary information or a program. In a case of using a wireless signal dedicated to position estimation, a wireless signal suitable for position estimation can be utilized, so that the position estimation processing is simplified. 
     The person detecting device  130  detects that a person exists near the person detecting device  130 . For example, the person detecting device  130  detects that a person exists within a predetermined range. Upon detecting that a person exists in proximity, the person detecting device  130  outputs person detection information indicating the detection to the controlling device  140 . The person detection information may be produced in a predetermined format. 
     The person detecting device  130  can be provided with, for example, a human proximity sensor that detects the proximity of a human in a non-contact manner or an image recognition sensor having a camera that captures an image and analyzing the camera image to detect the presence of a human in a specific region. 
     The person detecting device  130  can also be implemented by a wireless signal intensity sensor that detects the intensity of a wireless signal emitted from a mobile terminal such as a smartphone or tablet held by a person and determines that the person is close when a signal intensity equal to or greater than a predetermined value is detected. 
     Although these sensors can detect the proximity of a person with high probability, they are generally expensive. 
     The person detecting device  130  can also be implemented by a door opening/closing switch that detects the opening or closing state of a door of the room by a physical switch or a non-contact switch to determine that the person who opens or closes the door is at a close position. The person detecting device  130  may be implemented as an operation detecting device such as a household electric appliance or the like which is installed at a specific position and detects an operation by a person to detect that the person is at a close position. The person detecting device  130  can also be implemented as a sound generation source specifying device for specifying the position where a sound is generated by sensing the sound generated when a person walks or acts. 
     These devices can be implemented at a relatively low cost because they can be implemented by using simple on-off physical switches, buttons for operation in other devices, microphones, or the like. However, since these devices detect the proximity of a person only when a person conducts an operation or generates a sound, they cannot detect the proximity of a person when there is no human operation or sound generation. 
     The controlling device  140  detects the position of one of the persons  301 ,  302  in the room  300  on the basis of the reception intensity information from the receiving device  120  and the person detection information from the person detecting device  130 . 
     Here, although the controlling device  140  can be connected with the transmitting device  110 , the receiving device  120 , and the person detecting device  130  by wired connection, it can also be wirelessly connected with them if the wireless signal for position estimation is not affected. 
     Further, the controlling device  140  does not necessarily have to control the transmitting device  110 , the receiving device  120 , and the person detecting device  130 . However, in order to analyze the signal of the wireless communication with high accuracy, it is desirable that the controlling device  140  can control the transmission timing of the wireless signal from the transmitting device  110 , the reception sensitivity of the receiving device  120 , and the detection ability of the person detecting device  130 , among others. 
       FIG. 2  is a block diagram schematically illustrating a configuration of the controlling device  140 . 
     The controlling device  140  includes a reception intensity information input unit  141 , an analysis unit  142 , a storage unit  143 , an existing signal pattern extraction unit  146 , a person detection information input unit  147 , a clocking unit  148 , a transmitting device communication unit  149 , and a position estimation unit  150 . 
     The reception intensity information input unit  141  receives input of reception intensity information by the receiving device  120 . The input reception intensity information is supplied to the analysis unit  142 . 
     The analysis unit  142  functions as a signal pattern information generating unit that analyzes the wireless signal received by the receiving device  120  to generate signal pattern information. 
     For example, the analysis unit  142  uses the reception intensity indicated by the reception intensity information input to the reception intensity information input unit  141  in a predetermined period to generate signal pattern information indicating a signal pattern indicating the transition of the reception intensity in the predetermined period. The generated signal pattern information is stored as the existing signal pattern information in a database  144  to be described later in the storage unit  143 . The signal pattern information is supplied to the existing signal pattern extraction unit  146 . 
     The storage unit  143  stores information necessary for processing in the controlling device  140 . 
     For example, the storage unit  143  includes a database  144  and a position/time information storage unit  145 . 
     The database  144  is an existing signal pattern related information storage unit that associates existing signal pattern information with its related information and stores the associated information. 
     For example, the database  144  defines signal pattern information in the past as existing signal pattern information, associates the existing signal pattern information with related information generated when the existing signal pattern information was generated, and stores the associated information. The related information, which will be described later, includes estimated position information, elapsed time information, and person detecting device attribute information. 
     The position/time information storage unit  145  stores position/time information indicating a position and a time point at which a person is detected by the person detecting device  130 . Although not shown, in a case where the position estimation system  100  includes a plurality of person detecting devices  130 , the position/time information includes device identification information of the person detecting device  130  that transmitted the person detection information. 
     The existing signal pattern extraction unit  146  is a reading unit that reads out, from the database  144 , related information associated with one piece of the existing signal pattern information indicating a signal pattern most similar to the signal pattern indicated by the signal pattern information supplied from the analysis unit  142 , as existing signal pattern related information. 
     Since the signal pattern information supplied from the analysis unit  142  is already stored in the database  144  as the existing signal pattern information, the existing signal pattern extraction unit  146  extracts, from the database  144 , the most similar signal pattern except the signal pattern indicated by the same signal pattern information supplied from the analysis unit  142 . 
     Here, in a case where the database  144  stores a plurality of pieces of existing signal pattern information similar to the signal pattern indicated by the signal pattern information supplied from the analysis unit  142 , the existing signal pattern extraction unit  146  reads out, from the plurality of pieces of existing signal pattern information, related information associated with one piece of the existing signal pattern information in which the position indicated by the associated person detecting device attribute information is the same as the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147 . 
     Alternatively, in a case where the database  144  stores a plurality of pieces of the existing signal pattern information similar to the signal pattern indicated by the signal pattern information supplied from the analysis unit  142 , the existing signal pattern extraction unit  146  reads out, from the plurality of pieces of existing signal pattern information, related information associated with one piece of the existing signal pattern information in which the position indicated by the associated person detecting device attribute information is the same as the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147  and the elapsed time indicated by the associated elapsed time information is the shortest. 
     The person detection information input unit  147  receives input of the person detection information from the person detecting device  130 . 
     The person detection information is supplied to the position estimation unit  150 . 
     The clocking unit  148  measures time. Here, the time measured by the clocking unit  148  is assumed to be the current time. The clocking unit  148  supplies time information indicating the current time to the position estimation unit  150 . 
     When the person detection information is supplied from the person detection information input unit  147 , the position estimation unit  150  obtains the current time from the clocking unit  148 , generates position/time information indicating the position of the person detecting device  130  that transmitted the person detection information and the obtained time point, and stores the position/time information in the position/time information storage unit  145  of the storage unit  143 . 
     Here, it is assumed that the position estimation unit  150  already knows the position where the person detecting device  130  is disposed. For example, although not shown, it is assumed that position information indicating the position of the person detecting device  130  is stored in the storage unit  143 . 
     If there is only one person detecting device  130  in the room  300 , which is the space for performing detection, the person detecting device  130  may transmit person detection information indicating that a person has been detected. 
     On the contrary, in a case where a plurality of person detecting devices  130  are arranged in the room  300 , each of them may include device identification information to identify each device in the person detection information. The position estimation unit  150  specifies the position of the person detecting device  130  that transmitted the person detection information on the basis of the device identification information. 
     It should be noted that the person detection information may include information indicating the position of the person detecting device  130  that detected a person. 
     The transmitting device communication unit  149  communicates with the transmitting device  110 . For example, in a case where the controlling device  140  controls the timing or the like of a wireless signal to be transmitted from the transmitting device  110  when position detection is performed, the position estimation unit  150  controls the transmitting device  110  via the transmitting device communication unit  149 . 
     The transmitting device communication unit  149  may also receive input of transmitting device information, which is information about the transmitting device  110 . 
     In order to estimate the position of any person  301 ,  302  in the room  300 , the position estimation unit  150  uses at least any one piece of existing signal pattern related information supplied from the existing signal pattern extraction unit  146 , person detection information supplied from the person detection information input unit  147 , position/time information stored in the position/time information storage unit  145 , and time information from the clocking unit  148 . 
     For example, in a case where the person detection information input unit  147  receives input of the person detection information within a predetermined period during which the signal pattern is specified, the position estimation unit  150  estimates, to be the position where a person exists, the position of the person detecting device  130  that output the person detection information in the signal pattern. 
     In a case where the person detection information input unit  147  has received no input of the person detection information within a predetermined period during which the signal pattern is specified, when the position indicated by the person detecting device attribute information read by the existing signal pattern extraction unit  146  is the same as the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147 , and the elapsed time indicated by the elapsed time information read by the existing signal pattern extraction unit  146  is shorter than the predetermined time, the position estimation unit  150  estimates, to be the position where a person exists, the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147 . 
     Furthermore, in a case where the person detection information input unit  147  receives no input of the person detection information within a predetermined period during which the signal pattern is specified, when the position indicated by the person detecting device attribute information read by the existing signal pattern extraction unit  146  is the same as the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147 , and the elapsed time indicated by the elapsed time information read by the existing signal pattern extraction unit  146  is equal to or longer than the predetermined time, the position estimation unit  150  estimates, to be the position where a person exists, a corrected position calculated by correcting the position of the person detecting device  130  in which the person detection information was last input to the person detection information input unit  147  by a distance through which a person moves in the elapsed time since the person detection information was last input to the person detection information input unit  147 . 
     Then, the position estimation unit  150  stores estimated position information indicating the estimated position, elapsed time information indicating the elapsed time since the person detection information was last input to the person detection information input unit  147 , and person detecting device attribute information indicating the position of the person detecting device  130  that last input the person detection information to the person detection information input unit  147  in the database  144  as related information in association with corresponding existing signal pattern information stored in the database  144 . Although not shown, in a case where the position estimation system  100  includes a plurality of person detecting devices  130 , the person detecting device attribute information includes device identification information of the person detecting device  130  that transmitted the person detection information used for position estimation. 
     The position estimation unit  150  may output the estimated position information indicating the position estimated as described above to an external device via an output unit not shown. 
     For example, the estimated position information can be used as input information for another process such as action prediction. 
     As shown in  FIG. 3A , for example, some or all of the analysis unit  142 , the existing signal pattern extraction unit  146 , the clocking unit  148 , and the position estimation unit  150  described above can be implemented by a memory  10  and a processor  11  such as a CPU (Central Processing Unit) for executing a program stored in the memory  10 . Such a program may be provided through a network or recorded on a recording medium. That is, such a program may be provided, for example, as a program product. 
     Alternatively, as shown in  FIG. 3B , some or all of the analysis unit  142 , the existing signal pattern extraction unit  146 , the clocking unit  148 , and the position estimation unit  150  may be implemented by a processing circuit  12  such as a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array). 
     The storage unit  143  may be implemented by a recording device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). 
     The reception intensity information input unit  141 , the person detection information input unit  147 , and the transmitting device communication unit  149  may be implemented by a communication device such as an NIC (Network Interface Card). 
     Next, the processing of the controlling device  140  to receive the reception intensity signal and the person detection information, and to estimate the position will be described. 
       FIG. 4  is a flowchart illustrating an operation of the controlling device  140 . 
     First, the analysis unit  142  uses the reception intensity indicated by the reception intensity information input to the reception intensity information input unit  141  to specify a signal pattern and generates signal pattern information indicating the specified signal pattern (S 10 ). 
     For example, in a case where the position estimation system  100  includes one transmitting device  110 , part of the wireless signal transmitted from the transmitting device  110  is received by the receiving device  120  as a direct wave without circumventing by reflection or the like. Further, another part of the transmitted wireless signal collides an object having an influence on the path of the electromagnetic wave, such as the person  301 , and is received by the receiving device  120  as a reflected wave. In this case, since a difference occurs in the length of the path traveled by the wireless signal, which is an electromagnetic wave, the receiving device  120  receives the same wireless signal as a plurality of signals having a time difference. The electromagnetic waves arriving as reflected waves are generated under the influence of various objects in the room  300 , and the path lengths to the receiving device  120  are different from each other. Therefore, the two-dimensional information of the time in a short time and the reception intensity of the wireless signal received by the receiving device  120  is information reflecting the distribution of objects having an influence on the electromagnetic waves, including the persons  301 ,  302  in the room  300 . This is called the signal pattern of the received wireless signal. 
     Also, although not shown, in a case where the position estimation system  100  includes a plurality of transmitting devices  110 , each transmitting device  110  characterizes and transmits a wireless signal for each transmitting device  110 . In such a case, the signal pattern of the wireless signal received by the receiving device  120  has a more complicated configuration. Specifically, when different frequencies are assigned to each of the plurality of transmitting devices  110 , the signal pattern is identified as three-dimensional information of frequency, time, and signal intensity. 
     Also, although not shown, in a case where the position estimation system  100  includes a plurality of receiving devices  120 , each of the plurality of receiving devices  120  has a different linear distance from the transmitting device  110 , and also has a different path length through which a reflected wave from an object affecting an electromagnetic wave travels. Therefore, in such a case, the signal pattern is specified as three-dimensional information of the type of the receiving device  120 , time, and signal intensity. In such a case, the receiving device  120  includes the type of its own device in the reception intensity information. 
     Although not shown, in a case where the position estimation system  100  includes a plurality of transmitting devices  110  and a plurality of receiving devices  120 , a different frequency is assigned to each of the plurality of transmitting devices  110  in the same manner as described above. In such a case, the signal pattern is specified as four-dimensional information of the type of the receiving device  120 , frequency, time, and reception intensity. 
     Next, the analysis unit  142  arranges the specified signal pattern into a storable form to generate signal pattern information indicating the specified signal pattern, and stores the generated signal pattern in the database  144  (S 11 ). 
     It should be noted that, in order to store the related information in an associated manner in the subsequent step, a unique number is assigned to each pieces of the signal pattern information stored in step S 11 . 
     In addition, the analysis unit  142  supplies the signal pattern information generated in step S 10  together with the unique number to the existing signal pattern extraction unit  146 . 
     Next, in step S 10 , the position estimation unit  150  determines whether or not the person detection information is input to the person detection information input unit  147  after the input of the reception intensity information from the receiving device  120  is started (S 12 ). If the person detection information is input (Yes in S 12 ), the process proceeds to step S 16 , and if the person detection information is not input (No in S 12 ), the process proceeds to step S 13 . 
     In step S 13 , the existing signal pattern extraction unit  146  extracts a signal pattern most similar to the signal pattern indicated by the signal pattern information supplied from the analysis unit  142  in this time from the signal patterns indicated by the existing signal pattern information which is the past signal pattern information stored in the database  144 . In this case, extraction in this time is performed from the signal patterns indicated by the existing signal pattern information having a unique number other than the unique number supplied from the analysis unit  142 . 
     Here, since the signal pattern is constituted as a set of multidimensional number of states as described above, as a method for extracting the most similar signal pattern, there is a method for extracting the signal pattern having the shortest distance between two signal patterns. Distance functions capable of calculating a mathematical distance space, such as the Euclidean distance, the Mahalanobis distance, the Chebyshev distance, or the Minkowski distance, are used as preferable methods for calculating the distance between pieces of multi-dimensional information. 
     Next, the existing signal pattern extraction unit  146  reads out the related information stored in association with the signal pattern information indicating the extracted signal pattern (S 14 ). The related information includes estimated position information, elapsed time information, and person detecting device attribute information. 
     Next, the position estimation unit  150  reads out the latest position/time information from the position/time information storage unit  145  (S 15 ). The latest position/time information is information indicating the position of the person detection information input unit  147  that transmitted the last person detection information and the time point at which the last person detection information was transmitted. Then, the process proceeds to step S 16 . 
     In step  16 , the position estimation unit  150  uses at least any one piece of existing signal pattern related information supplied from the existing signal pattern extraction unit  146 , person detection information supplied from the person detection information input unit  147 , position/time information stored in the position/time information storage unit  145 , and time information from the clocking unit  148  to estimate the position of any one of the persons  301 ,  302  in the room  300 . 
     Specifically, in a case where the person detection information is input in step S 12  (Yes in step S 12 ), the position estimation unit  150  estimates, to be the position where any one of the persons  301 ,  302  exists, the position of the person detecting device  130  that transmitted the person detection information. 
     When the person detection information is input, performing such estimation eliminates the necessity of the processing for searching the database  144  by the existing signal pattern extraction unit  146 , thereby reducing the load of the processing for position estimation. Further, the position of any one of the persons  301 ,  302  can be estimated with higher accuracy than the position estimated by comparing the signal patterns of the wireless signals. 
     On the contrary, in a case where the person detection information is not input in step S 12  (No in S 12 ), the position estimation unit  150  estimates the position of the person  301  or  302  by using the existing signal pattern related information supplied from the existing signal pattern extraction unit  146 , the latest position/time information stored in the position/time information storage unit  145 , and the time information from the clocking unit  148 . 
     Specifically, when the position indicated by the person detecting device attribute information included in the existing signal pattern related information coincides with the position indicated by the latest position/time information, the position estimation unit  150  estimates the position of the person  301  or  302  from the position indicated by the latest position/time information. 
     For example, when the elapsed time indicated by the elapsed time information included in the existing signal pattern related information is shorter than a predetermined time, the position estimation unit  150  estimates the position of the person  301  or  302  as the position indicated by the latest position/time information. 
     On the contrary, when the elapsed time indicated by the elapsed time information included in the existing signal pattern related information is equal to or longer than a predetermined time, the position estimation unit  150  corrects the position indicated by the latest position/time information, because there is a high possibility that the person  301  or  302  exists at a position remote from the person detecting device  130 . 
     As for the correction of the position, for example, the position estimation unit  150  can perform the following processing. 
     In a case where the position estimation system  100  includes one person detecting device  130 , on the basis of the assumption that the walking speeds of the persons  301 ,  302  are constant, the position estimation unit  150  calculates the distance from the person detecting device  130  by multiplying the walking speed by the elapsed time from the time point indicated by the latest position/time information to the current time indicated by the time information. In such a case, the position estimation unit  150  estimates that the position on the circular arc, which is concentrically separated by the calculated distance from the position of the person detecting device  130 , is the position of the person  301  or  302 . 
     In a case where the position estimation system  100  includes a plurality of person detecting devices  130 , the position estimation unit  150  can more accurately estimate the positions of the persons  301 ,  302 . 
     In this case, the position estimation unit  150  reads the latest position/time information and the second latest position/time information from the position/time information storage unit  145 . In a case where the positions indicated by these pieces of information are different, the position estimation unit  150  can estimate the position by assuming that the movement of a person is a constant velocity linear motion calculated between the two positions as follows. 
     The position estimation unit  150  calculates an inter-device distance D which is a distance between positions indicated by these pieces of the information. 
     Next, the position estimation unit  150  calculates the required time T required for a person to move the inter-device distance D from the time points indicated by these pieces of the information. 
     Then, the position estimation unit  150  can calculate the walking speeds S of the persons  301 ,  302  by dividing the inter-device distance D by the required time T. 
     Thus, the position estimation unit  150  can estimate a position between the position indicated by the second latest position/time information and the position indicated by the latest position/time information in accordance with the generated time of the signal pattern information generated during the period from the time point indicated by the second latest position/time information to the time point indicated by the latest position/time information. 
     In such a case, the position estimation unit  150  suspends estimations of the positions from the time when the person detection information is detected until the next person detection information is detected, and may estimate a position between the positions indicated by the two pieces of the position/time information in a case where the position of the person detecting device  130  that transmitted the person detection information is different when the latest person detection information is input. 
     It should be noted that, in a case where the positions of the person detecting devices  130  that transmitted the person detection information are the same, the position estimation unit  150  may estimate the concentric positions about the positions of the person detecting devices  130  as in the case where one person detecting device  130  is provided. 
     Furthermore, when the position indicated by the person detecting device attribute information included in the existing signal pattern related information does not match the position indicated by the latest position/time information, the position estimation unit  150  deletes the existing signal pattern information stored in step S 11  without estimating the position with respect to the signal pattern information generated by the analysis unit  142 . 
     Next, in a case where the estimation of the position has been made, the position estimation unit  150  generates related information of the existing signal pattern information stored in the database  144  in step S 11 , and stores the generated related information in the database  144  in association with the existing signal pattern information (S 17 ). As for the association, a unique number assigned to the signal pattern information may be used. 
     Then, the position estimation unit  150  determines whether or not to end the process in accordance with, for example, an instruction from an operator (S 18 ). If the process is not ended (No in S 18 ), the process returns to step S 10 . 
     Thus, by utilizing the reception intensity information and the person detection information in combination, the controlling device  140  can perform position estimation with high estimation accuracy on the basis of the position of the person detecting device  130 . 
     In addition, even in a case where the person detecting device  130  is not a device capable of detecting the presence of a person with a high probability, such as a person proximity sensor described above, but is a device in which the person detection information is not always transmitted, such as when using device operation information of a household electrical appliance installed at a specific position, the signal patterns of the wireless signal will have a similarity regardless of the presence or absence of the device operation, so that the position can be estimated as long as the device operation or the like has been performed in the past. 
     Further, in the flowchart explained above, because the position of the person  301  or  302  can be estimated once the person detection information is input by the person detecting device  130 , the estimated position information can be recorded together with the signal pattern specified by the received signal intensity information, and the stored information can be used as an existing signal pattern in the next position estimation processing. Therefore, it is not necessary to prepare the database  144  in advance as in the prior art. 
     In the flowchart shown in  FIG. 4 , in step S 12 , it is determined whether or not the person detecting device  130  has detected the proximity of a person, and if the proximity of a person has been detected, the processing in steps S 13  to S 15  are skipped, but the present embodiment is not limited to such an example. The detection by the person detecting device  130  and the processes from steps S 13  to S 15  may be performed in parallel, and if a predetermined time has elapsed since the process of step S 10  started, the process may proceed to step S 16 . In such a case, when the detection by the person detecting device  130  is performed, giving priority to the position of the person detecting device  130  can improve the estimation accuracy of the position of the person  301  or  302 . 
     In the flowchart shown in  FIG. 4 , the most similar signal pattern is extracted in step S 13 , but the present embodiment is not limited to such an example. 
     For example, in a case where the database  144  stores a plurality of similar signal patterns, whose distances between the signal patterns are the same or within a predetermined range, the existing signal pattern extraction unit  146  obtains related information corresponding to the plurality of similar signal patterns in step S 13 , and supplies them to the position estimation unit  150 . The position estimation unit  150  may specify one piece of related information indicating the same position as the position of the person detecting device  130  that transmitted the latest person detection information stored in the position/time information storage unit  145 , and use the specified related information. This is based on the assumption that, although there is a case where the position of the person  301  or  302  in the room  300  is completely different even if the signal pattern is similar, a past signal pattern more similar to the current signal pattern will be extracted if the position is the same as that of the person detecting device  130  which transmitted the person detection information just before. 
     Furthermore, when there are a plurality of signal patterns having the same positions, the position estimation unit  150  may select one piece of the related information having the shortest elapsed time. This is based on an assumption that, since the short elapsed time means that the elapsed time since the time point at which the person detecting device  130  identifies the person at the specific position is short, the reliability of the estimated position is higher. 
     Next, a description will be given of how the position estimation system  100  configured as described above can effectively estimate, when there are two persons in a room which is the space for detection, the position of any one of the persons. 
       FIG. 5  is a schematic diagram illustrating a first example in which the person  301  and the person  302  exist in the room  300 . 
     In the first example shown in  FIG. 5 , it is assumed that the person  301  is in a position close to the person detecting device  130  and the person detection information is output from the person detecting device  130 . 
     The wireless signal transmitted from the transmitting device  110  is received by the receiving device  120  as a specific signal pattern P by reflection from the person  301 , the person  302 , and other objects affecting electromagnetic waves. 
     According to the flowchart shown in  FIG. 4 , since the person  301  exists at a position close to the person detecting device  130 , the position information of the person detecting device  130  and the signal pattern P received at this time are recorded in the database  144  together. 
       FIG. 6  is a schematic diagram illustrating a second example in which the person  301  and the person  302  exist in the room  300 . 
     In the second example, the position of the person  302  is different from that in the first example. 
     Since the wireless signal reflected by the person  302  is different from the first example, in the second example, the receiving device  120  receives the wireless signal with a signal pattern Q different from the signal pattern P in the first example. 
     On the basis of only the signal pattern P and the signal pattern Q, it is difficult to recognize that these are the signal patterns when the person  301  is at the same position. 
     For this reason, when performing position estimation only by the signal pattern of the wireless communication as in the prior art, it was necessary to perform a preparation work by arranging the person  301  and the person  302  at corresponding positions in advance, obtaining the signal pattern P and the signal pattern Q, and recording the signal pattern information indicating each signal pattern in association with the position information of the person detecting device  130 . Since the positions where the person  302  exists in the room  300  are innumerable, it is difficult to perform such preparation work and store necessary information because the amount of data to be stored is enormous. 
     In contrast, in the present embodiment, when obtaining the signal pattern P in the first example, the controlling device  140  records the signal pattern information indicating the signal pattern P in the database  144  together with the position information of the person detecting device  130 . Further, when the controlling device obtains the signal pattern Q in the second example, the controlling device  140  stores the signal pattern information indicating the signal pattern Q in the database  144  together with the position information of the person detecting device  130 . Therefore, the existing signal pattern recorded according to the position of the person  302  is recorded as necessary, and when the person  302  exists at the position recorded once, the position of the person  301  can be accurately estimated. 
     Although it is difficult to predict the position of the person  301  or the person  302  in each room  300 , the combination has a high probability of existence due to, for example, allocation of the room  300  or arrangement of furniture. In the present embodiment, by preferentially recording the positions where the person  301  or the person  302  actually exists, it is possible to reduce the possibility that the amount of data enormously increases and to perform the position estimation with higher accuracy. 
     Although  FIG. 5  and  FIG. 6  have been described with reference to the case of two persons, similar effects can be expected for objects affecting the arrival of electromagnetic waves. 
     For example, even when an event affecting the electromagnetic wave environment in the room  300  such as opening and closing of a metal door, installation or removal of a large household electrical appliance, or construction of an adjacent building occurs after the installation of the position estimation system  100 , the signal patterns after the occurrence of the effect and the position information derived from the person detecting device  130  are recorded in the database  144 , so that the position of a person can be estimated with high accuracy. 
     In the present embodiment, the position estimation processing for the room  300  has been described, positions of persons can be estimated for the entire building with a plurality of rooms or for one floor of the building as long as the wireless signal from the transmitting device  110  to the receiving device  120  is reachable. 
     Since the position estimation system  100  of the present embodiment uses information indicating that a person exists at a specific position in addition to information from the receiving device  120  when estimating a position, it is not necessary to record the signal pattern information in advance, so that the amount of the signal pattern information to be recorded is reduced and the signal pattern can be collated in a short time. 
     In addition, even if there is another person who affects the signal pattern in the estimation target environment and the position of the other person changes variously, the signal pattern can be stored as data belonging to the person to be detected, and the database  144  can be expanded by learning. Therefore, the position of the estimation target person can be estimated with respect to the position of the person detecting device  130  as the reference position, and more accurate position estimation can be performed in advance. 
     The position estimation system  100  according to the present embodiment can record a signal pattern related to the position of a person in learning manner even when two or more persons exist in the room, and can register constantly existing positions in the database  144  at any time. Therefore, a similar past signal pattern can be extracted, and the position can be estimated. 
     Also, even when a plurality of signal patterns similar to the past signal patterns are included and the past signal patterns similar to the current signal patterns cannot be uniquely specified, the position similar to the nearest person detecting device  130  can be estimated, and the possibility of erroneously estimating the position away from the correct answer can be reduced. 
     DESCRIPTION OF REFERENCE CHARACTERS 
       100  position estimation system,  110  transmitting device,  120  receiving device,  130  person detecting device,  140  controlling device,  141  reception intensity information input unit,  142  analysis unit,  143  storage unit,  146  existing signal pattern extraction unit,  147  person detection information input unit,  148  clocking unit,  149  transmitting device communication unit,  150  position estimation unit