JP6446931B2 - Position estimation system, position estimation method, and position estimation apparatus - Google Patents

Description

  The present invention relates to a position estimation system and a mobile station that estimate a position by wireless communication.

  Conventionally, in order to estimate the position of a mobile station, a position estimation method using the radio field intensity of a signal transmitted and received between a fixed station and a mobile station is known. This is a radio map (a radio field strength feature obtained by measuring radio field strength for each location in advance), and the radio map and radio map between the mobile station and the fixed station whose location is to be estimated. This is a method of estimating the position of the mobile station by matching with. Using this method, for example, the location of an article in a hospital or warehouse can be confirmed.

  However, the radio field intensity between the mobile station and the fixed station greatly fluctuates due to environmental fluctuations (for example, changes in temperature and humidity, moving or removing large objects in the space, etc.). Then, the difference between the radio wave intensity measured at the time of position estimation and the radio map created in advance becomes large, and the position of the mobile station may be erroneously estimated.

  Therefore, in order to suppress the discrepancy between the measured radio field intensity and the radio map, the radio map is adapted by periodically collecting the measured radio field intensity as observation data (that is, the radio map is updated to the latest radio environment). Have been proposed (for example, see Patent Document 1).

JP2013-205226A

  However, the technique disclosed in Patent Document 1 has a problem that it takes time to collect observation data and adapt a radio map because the observation data is periodically collected manually.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a position estimation system and a mobile station that can efficiently collect observation data and adapt a radio map.

  In order to solve the above-described problem, a position estimation system according to an aspect of the present invention is a position estimation system that estimates a position of a mobile station with respect to at least one fixed station, and features of radio wave intensity at each of a plurality of positions A storage unit that stores a radio map indicating the position, a designation unit that designates the mobile station whose position is to be estimated, and a radio field intensity between the mobile station and the fixed station designated by the designation unit A position estimation unit that estimates the position of the mobile station by collating the measured value of the radio field intensity obtained by the radio map, and a notification unit that notifies the position of the mobile station estimated by the position estimation unit; A receiving unit that receives an operation indicating whether or not the position of the mobile station estimated by the position estimating unit is correct, and an operation that indicates that the position of the mobile station is correct. When only attached, based on the measurement value of the radio wave strength, and an adaptation unit that performs processing in which adaptation to update the radio map.

  According to this, when the user inputs whether or not the position of the mobile station notified from the position estimation system is correct, the radio field intensity between the mobile station and the fixed station is measured when the user goes to pick up the article. Observation data, which is a measurement value of the radio field intensity obtained by doing so, is collected. Further, the estimated position of the mobile station is linked to the observation data after it is actually confirmed by the user whether or not it is correct. Therefore, observation data collection and radio map adaptation can be performed efficiently.

  Further, the information processing apparatus includes a notification unit that notifies the presence of the mobile station, wherein the reception unit further receives an operation of inputting a correct position of the mobile station that is notified of the presence by the notification unit, and the adaptation unit includes: When the reception unit receives an operation indicating that the position of the mobile station is not correct, the correct position is determined based on the correct position of the mobile station further received by the reception unit and the measured value of the radio field intensity. The radio map may be adapted.

  According to this, even when the position of the mobile station notified from the position estimation system is incorrect, the user can recognize the correct position of the mobile station by notifying the presence of the mobile station by the notification unit. The correct position of the mobile station and the observation data are linked by inputting the correct position. Therefore, observation data collection and radio map adaptation can be performed efficiently.

  In addition, the adaptation unit may not adapt the radio map if the magnitude of the difference between the radio field intensity measurement value and the radio map is larger than a predetermined magnitude.

  According to this, when observation data whose deviation from the radio map is too large is obtained, the adaptation of the radio map is not performed, so that it is possible to suppress the degradation of the performance of the radio map.

  Further, the reception unit may request authentication when receiving an operation indicating whether or not the position of the mobile station estimated by the position estimation unit is correct.

  According to this, only the authenticated user can adapt the radio map.

  A mobile station according to an aspect of the present invention is a mobile station whose position with respect to at least one fixed station is estimated, and measurement of radio field intensity obtained by measuring radio field intensity with the fixed station. A communication unit that transmits a value and a reception unit that receives an operation indicating whether or not the estimated position of the mobile station is correct, and the communication unit indicates that the estimated position of the mobile station is correct When the reception unit receives the operation, a signal indicating that the position of the mobile station is correct is transmitted.

  According to this, when the user inputs whether or not the position of the mobile station estimated by the position estimation device is correct, the radio field strength between the mobile station and the fixed station can be reduced when the user goes to pick up the mobile station. Observation data, which is a measurement value of radio field intensity obtained by measurement, is collected. Further, the estimated position of the mobile station is linked to the observation data after it is actually confirmed by the user whether or not it is correct. Therefore, observation data collection and radio map adaptation can be performed efficiently.

  And a notification unit that notifies the presence of the mobile station, wherein the communication unit receives an instruction to notify the presence of the mobile station, and the notification unit receives the instruction by the communication unit, The presence of the mobile station may be notified.

  According to this, since the mobile station reports its own presence, the user can easily confirm the presence of the mobile station.

  A position estimation method according to an aspect of the present invention is a position estimation method for estimating a position of a mobile station with respect to at least one fixed station, the designation step for designating the mobile station whose position is estimated, and a designation step The radio field intensity measurement value obtained by measuring the radio field intensity between the mobile station and the fixed station is collated with a radio map indicating the characteristics of the radio field intensity at each of a plurality of positions stored in advance. A position estimation step for estimating the position of the mobile station, a notification step for notifying the estimated position of the mobile station, and a reception step for receiving an operation indicating whether or not the estimated position of the mobile station is correct. When an operation indicating that the position of the mobile station is correct is accepted, an adaptation is performed, which is a process of updating the radio map based on the measurement value of the radio field intensity. And a adaptation step.

  According to this, when the user inputs whether or not the position of the mobile station estimated by the position estimation method is correct, the radio field strength between the mobile station and the fixed station can be reduced when the user goes to pick up the mobile station. Observation data, which is a measurement value of radio field intensity obtained by measurement, is collected. Further, the estimated position of the mobile station is linked to the observation data after it is actually confirmed by the user whether or not it is correct. Therefore, observation data collection and radio map adaptation can be performed efficiently.

  The present invention can be realized not only as an apparatus but also as a method using processing means constituting the apparatus as steps. Also, the steps can be realized as a program that causes a computer to execute the program, or can be realized as a computer-readable recording medium such as a CD-ROM that records the program. It can also be realized as information, data, or a signal indicating the program. These programs, information, data, and signals may be distributed via a communication network such as the Internet.

  According to the present invention, observation data collection and radio map adaptation can be performed efficiently.

The block diagram which shows the function of the position estimation system in embodiment Diagram showing an example of a mobile station Diagram showing division of area for measuring radio field strength Flow chart showing the procedure for creating a radio map The figure which shows frequency distribution of the value which measured the field intensity in position A1 The figure which shows the probability distribution of the electromagnetic wave intensity in position A1 The figure which shows the probability distribution of the electromagnetic wave intensity in position A2 The figure which shows the probability distribution of the electromagnetic wave intensity in position A3 Communication sequence diagram showing the operation of the position estimation system in the embodiment Figure showing an image of radio map adaptation

  Hereinafter, a position estimation system and a mobile station according to an aspect of the present invention will be specifically described with reference to the drawings.

  Each of the embodiments described below shows a preferred specific example of the present invention. Numerical values, shapes, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are described as optional constituent elements that constitute a more preferable embodiment.

  In addition, the same code | symbol is attached | subjected to the same component and description may be abbreviate | omitted.

(Embodiment)
[1. Overall configuration of position estimation system]
FIG. 1 is a block diagram illustrating a functional configuration of a position estimation system 1 according to the embodiment.

  In FIG. 1, a position estimation system 1 according to the present embodiment is a system that can estimate the positions of these devices by attaching a mobile station 30 to a medical device such as a blood pressure monitor or an electrocardiograph, for example. The position estimation system 1 includes a position estimation device 10, a fixed station 20, and a mobile station 30.

[2. Functional configuration of position estimation device]
The position estimation device 10 is a device that estimates the position of the mobile station 30, and includes a storage unit 11, a specification unit 12, a position estimation unit 13, a communication unit 14, a notification unit 15, and an adaptation unit 16.

  The storage unit 11 receives a radio map indicating a relationship with radio wave intensity (RSSI (Received Signal Strength Indication)) at each of a plurality of positions, the position of the mobile station 30 estimated by the position estimation unit 13 described later, and the communication unit 14. The observed data is stored. In the present embodiment, the radio map is represented using a probability distribution of radio wave intensity as a characteristic of the radio wave intensity at each of a plurality of positions. The radio field intensity at each of the plurality of positions is the radio field intensity from the fixed station 20 (first to third APs 20a to 20c) to the mobile station 30 at each of the plurality of positions, or at each of the plurality of positions. It is the radio field intensity from the mobile station 30 to the fixed station 20. Here, the radio field intensity at each of the plurality of positions is the radio field intensity from the fixed station 20 to the mobile station 30 at each of the plurality of positions. In the present embodiment, the radio map representing the relationship with the radio wave intensity at each of a plurality of positions using a probability distribution is used. However, the present invention is not limited to this. For example, the radio map may be represented using other characteristics of radio field strength.

  The designation unit 12 is a processing unit that designates the mobile station 30 whose position is estimated, and includes, for example, a keyboard, a numeric keypad, or a touch panel. When the mobile station 30 whose position is to be estimated is designated on the touch panel, for example, the communication unit 14 described later transmits an instruction to generate observation data to the mobile station 30 designated by the designation unit 12.

  The position estimating unit 13 measures the radio field intensity obtained by measuring the radio field intensity between the mobile station 30 and the fixed station 20 specified by the specifying unit 12 (here, from the fixed station 20 to the mobile station 30). It is a processing unit that estimates the position of the mobile station 30 by comparing observation data that is a measurement value with a radio map.

  The communication unit 14 is a processing unit that transmits and receives signals. Specifically, the communication unit 14 transmits a search and notification instruction to the mobile station 30, receives observation data, and receives an operation result received by the receiving unit 33 described later. In the present embodiment, these signals are transmitted / received to / from the communication unit 31 of the mobile station 30 through the communication unit 21 of the fixed station 20. Note that the communication unit 14 may directly transmit and receive signals to and from the communication unit 31 of the mobile station 30.

  The notification unit 15 is a processing unit that notifies the position of the mobile station 30 estimated by the position estimation unit 13 and receives a notification instruction. For example, a display unit such as a display and a keyboard, a numeric keypad, a touch panel, or the like And an input unit. For example, by displaying the estimated position of the mobile station 30 on the display, the user is notified of the position of the mobile station 30. Further, for example, when a notification instruction is input on the touch panel, the communication unit 14 transmits a notification instruction to the mobile station 30 whose position is estimated.

  When the accepting unit 33 described later accepts an operation indicating that the position of the mobile station 30 is correct, the adaptation unit 16 receives observation data that is a measurement value of the radio field intensity from the fixed station 20 to the mobile station 30; Based on the position of the mobile station 30 estimated by the position estimation unit 13, the processing unit performs adaptation of the radio map (that is, updates the radio map to approach the latest radio wave environment).

[3. Functional configuration of fixed station]
The fixed station 20 is a wireless LAN (Local Area Network) AP (Access Point) that is wirelessly connected to the position estimation device 10 and the mobile station 30, and includes a communication unit 21. In the present embodiment, a first AP 20a, a second AP 20b, and a third AP 20c are arranged as the fixed station 20 (the second AP 20b and the third AP 20c are shown in FIG. 3 described later). In FIG. 1, the fixed station 20 is shown as the first AP 20a.

  The communication unit 21 is a processing unit that transmits and receives signals between the communication unit 14 of the position estimation device 10 and the communication unit 31 of the mobile station 30. Specifically, the communication unit 21 included in the fixed station 20 (first AP 20 a) receives a signal from the position estimation device 10, transmits the signal to the mobile station 30, and receives a signal from the mobile station 30. Is transmitted to the position estimation apparatus 10. That is, a signal is relayed between the position estimation device 10 and the mobile station 30. It should be noted that at least one of the first to third APs 20a to AP20c may relay a signal between the position estimation device 10 and the mobile station 30, and two or more may relay. In the present embodiment, the communication unit 21 relays signals between the position estimation apparatus 10 and the mobile station 30, but relays signals between the position estimation apparatus 10 and the mobile station 30. You don't have to. That is, the position estimation apparatus 10 and the mobile station 30 may directly transmit and receive signals.

  In addition, the communication unit 21 transmits a measurement target signal of radio field intensity. For example, a signal called a beacon periodically transmitted from the first to third APs 20a to 20c is used as the measurement signal for the radio wave intensity. That is, the communication unit 21 of each AP periodically transmits a beacon to the mobile station 30. Note that the communication unit 21 of each AP may transmit a beacon at an arbitrary timing. In addition, since the beacon transmitted from each AP includes a signal representing a MAC (Media Access Control) address unique to each AP, the mobile station 30 individually determines the radio wave intensity of the beacon transmitted from each AP. It can be measured.

[4. Functional configuration of mobile station]
The mobile station 30 is a wireless LAN compatible wireless tag (a device including an antenna and an IC (Integrated Circuit)). Articles that do not have a communication function are regarded as mobile stations 30 by attaching mobile stations 30 that are wireless tags. The mobile station 30 is affixed to a plurality of articles (for example, a medical device such as a blood pressure monitor or an electrocardiograph). The mobile station 30 includes a communication unit 31, an observation data generation unit 32, a reception unit 33, and a notification unit 34.

  The communication unit 31 is a processing unit that transmits and receives signals. Specifically, a search and notification instruction for the mobile station 30 is received, observation data that is a measurement value of the radio field intensity obtained by measuring the radio field intensity with the fixed station 20, and reception described later The operation result received by the unit 33 is transmitted. In the present embodiment, these signals are transmitted / received to / from the communication unit 14 of the position estimation apparatus 10 via the communication unit 21 of the fixed station 20. Note that the communication unit 31 may directly transmit and receive signals to and from the communication unit 14 of the position estimation device 10.

  Further, the communication unit 31 receives a beacon transmitted from the fixed station 20.

  The observation data generation unit 32 is a processing unit that measures the radio field intensity of the beacon received by the communication unit 31 and generates observation data that is a measurement value of the radio field intensity from the fixed station 20 to the mobile station 30.

  The receiving unit 33 is, for example, a button that receives an operation indicating whether or not the position of the mobile station 30 estimated by the position estimating unit 13 is correct. In order to receive an operation indicating whether or not the position of the mobile station 30 is correct, the receiving unit 33 may include at least a correct button, but in this embodiment, a correct button 33a, an incorrect button 33b, and a numeric keypad 33c. Is provided. In addition, when receiving an operation indicating whether the position of the mobile station 30 estimated by the position estimation unit 13 is correct, the reception unit 33 requests authentication such as a user ID or a password.

  The notification unit 34 is, for example, a speaker that notifies the presence of the mobile station 30. The notification unit 34 sounds an alarm, for example, when the communication unit 31 receives a notification instruction to the mobile station 30.

  FIG. 2 is a diagram illustrating an example of the mobile station 30. As shown in FIG. 2, the mobile station 30 includes a button, a speaker, and the like, and the user operates the button. Furthermore, the mobile station 30 has a size that can be handled by, for example, a palm so that the user can easily handle and attach the mobile station 30 to an article.

[5. Radio map creation procedure]
Next, a procedure for creating a radio map stored in the storage unit 11 will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a diagram showing division of an area for measuring radio wave intensity. The radio wave intensity in each region divided by the grid indicated by the dotted line in FIG. 3 is repeatedly measured to create a frequency distribution. The shape and size of each divided area are appropriately determined according to the measurement accuracy, the floor plan of the building, the required position estimation accuracy, and the like. Note that the measurement may be performed using the mobile station 30 used in position estimation, or may be performed using another measuring device. The above frequency distribution creation process is performed for all grids to create a radio map.

  Next, a procedure for creating a radio map will be described.

  FIG. 4 is a flowchart showing a procedure for creating a radio map.

  First, the position where the radio field intensity is measured is determined (S10). Next, the fixed station 20 to be measured at the determined position is determined as the first AP 20a (S11). Then, the radio field intensity from the first AP 20a is repeatedly measured (S12), and the measured value of the radio field intensity is accumulated to create a frequency distribution (S13). After the accumulation of measurement values is completed, the fixed station 20 to be measured is changed from the first AP 20a to the second AP 20b (S14, S11).

  Similarly, after the radio field intensity is measured and accumulated for the second AP 20b and the third AP 20c, the measurement position is moved to the next position (S15, S10).

  Similarly, for the next measurement position, the radio field intensity measurement and the measurement value accumulation from each AP are performed.

After the radio wave intensity measurement and measurement value accumulation at all measurement positions are completed and the frequency distribution at all measurement positions is created, a probability distribution is created from the frequency distribution (S16). In this embodiment, the case where a probability distribution is created by approximating a frequency distribution by a mixed normal distribution will be described, but the probability distribution is created not only by approximation by a mixed normal distribution but also by other various methods. Can do. Here, by using a mixed normal distribution composed of M normal distributions that can sufficiently approximate an arbitrary frequency distribution, the weight w _m , the average μ _m , and the variance σ ² _m (m = 1 to ²⁾ for each normal distribution. Likelihood to be described later is calculated using 3M parameters of M). Each parameter is estimated by, for example, an EM (Expectation Maximization) algorithm. When the parameter calculation of the mixed normal distribution is completed, the radio map creation procedure is completed.

  FIG. 5 is a diagram showing a frequency distribution of values obtained by measuring the radio wave intensity from each AP at the position A1 in FIG. The appearance frequencies of the radio field intensities from the first AP 20a, the second AP 20b, and the third AP 20c are represented by circles, squares, and triangles, respectively.

  FIG. 6 is a diagram showing a probability distribution obtained by approximating each frequency distribution shown in FIG. 5 with a mixed normal distribution. Appearance probabilities of radio field intensities from the first AP 20a, the second AP 20b, and the third AP 20c are represented by a solid line, an alternate long and short dash line, and a dotted line, respectively. The radio map at the position A1 is created in this way.

  7 and 8 are diagrams showing probability distributions approximating respective frequency distributions of the radio field intensity measurement values at the positions A2 and A3 in FIG. Appearance probabilities of radio field intensities from the first AP 20a, the second AP 20b, and the third AP 20c are represented by a solid line, an alternate long and short dash line, and a dotted line, respectively.

  In this way, a radio map is created in all the regions divided by the grid indicated by the dotted lines in FIG.

[6. Position estimation method]
Next, a position estimation method in the position estimation unit 13 will be described.

A value representing the degree of similarity between the measured value of the radio field intensity from the fixed station 20 to the mobile station 30 measured at a certain position and the probability distribution at each position of the radio map is referred to as likelihood. That is, the position of the radio map with the highest likelihood is estimated as the position of the mobile station 30. If the probability distribution is created by the normal mixture, when the radio wave intensity from N fixed station _{20 (AP n (n = 1~N} )) to the mobile station 30 and _{r n,} the likelihood at position _{p i} L (P _i ) is obtained using the following equations 1 and 2.

Here, r _n is the radio wave intensity from AP _n measured by the mobile station 30, W _{m, n} (m = 1 to M) is a weight for each normal distribution of the n-th fixed station 20, and μ _{m, n} is The mean for each normal distribution of the nth fixed station 20, σ ² _{m, n} represents the variance for each normal distribution of the nth fixed station 20.

From Equations 1 and 2, the likelihood L (p _i ) at each position is calculated, and the position p _i with the largest likelihood L (p _i ) is estimated as the position of the mobile station 30. In this way, the position of the mobile station 30 is estimated.

[7. Operation of position estimation system]
Next, the operation of the position estimation system 1 according to the present embodiment configured as shown in FIG. 1 will be described.

  FIG. 9 is a communication sequence diagram illustrating the operation of the position estimation system 1 according to the embodiment. Here, a communication procedure among the position estimation device 10, the fixed station 20 (first AP 20a), and the mobile station 30 is shown.

  First, an article to be searched is input by the user to the designation unit 12 of the position estimation device 10 (S20). The mobile station 30 is affixed to the article to be searched, and the designation unit 12 designates the mobile station 30 affixed to the article to be searched.

  The communication unit 14 of the position estimation apparatus 10 transmits an observation data generation instruction for the mobile station 30 designated by the designation unit 12 to the fixed station 20 (S21).

  The communication unit 21 of the fixed station 20 that has received the observation data generation instruction further transmits the observation data generation instruction to the mobile station 30 (S22).

  The communication unit 31 of the mobile station 30 that has received the observation data generation instruction receives a beacon transmitted from each AP. The observation data generation unit 32 measures the radio field intensity of the received beacon and generates observation data that is a measurement value of the radio field intensity (S23). Then, the communication unit 31 transmits the generated observation data to the fixed station 20 (S24).

  The communication unit 21 of the fixed station 20 further transmits the received observation data to the position estimation device 10 (S25).

  The position estimation unit 13 of the position estimation apparatus 10 estimates the position of the mobile station 30 by collating the observation data received by the communication unit 14 with a radio map (S26). That is, the position estimation unit 13 compares the radio map and the observation data at each of the plurality of positions, and estimates the position of the radio map where the radio wave intensity distribution similar to the observation data is seen as the position where the mobile station 30 exists. To do.

  The notification unit 15 displays the position of the mobile station 30 estimated by the position estimation unit 13 on a display, for example, and notifies the user (S27). Further, an instruction to notify the estimated mobile station 30 is input to, for example, the touch panel (S28). When the notification instruction is not input, the notification instruction is not transmitted to the mobile station 30, and therefore the mobile station 30 does not notify.

  When an instruction to notify the mobile station 30 notified to the notification unit 15 is input, the communication unit 14 transmits a notification instruction to the fixed station 20 (S29), and the communication unit 21 of the fixed station 20 moves. A notification instruction is transmitted to the station 30 (S30).

  When the communication unit 31 of the mobile station 30 receives the notification instruction, for example, the speaker of the notification unit 34 sounds a sound or an alarm and notifies the presence of itself to the surroundings (S31). FIG. 2 shows an example of the mobile station 30 that is informing.

  A user who has picked up the mobile station 30 can easily confirm the presence of the mobile station 30 by notifying the mobile station 30 as shown in FIG.

  When the mobile station 30 is in the position notified by the notification unit 15, the user presses the correct button 33a of the reception unit 33 provided in the mobile station 30 as shown in FIG. 2 (S32). At this time, for example, when a user ID or the like is input with the numeric keypad 33c as shown in FIG. 2, the accepting unit 33 accepts an operation indicating whether the answer is correct or incorrect.

  When the correct button 33a is pressed, the communication unit 31 transmits a signal indicating that the position of the mobile station 30 is correct to the fixed station 20 (S33). Further, the communication unit 21 of the fixed station 20 transmits a signal indicating that the position of the mobile station 30 is correct to the position estimation device 10 (S34).

  When the communication unit 14 of the position estimation apparatus 10 receives a signal indicating that the position where the mobile station 30 exists is correct, the adaptation unit 16 receives the signal when the position estimation unit 13 estimates the position of the mobile station 30. Based on the observed data, the radio map at the position corresponding to the position where the mobile station 30 exists is adapted (S35).

  When the correct button 33a provided in the mobile station 30 is pressed, the radio wave intensity from each AP is measured again, and observation data that is a measurement value of the radio wave intensity may be generated. As a result, the radio map is adapted based on the latest observation data in the radio wave environment.

  Further, the adaptation unit 16 of the position estimation apparatus 10 may not perform radio map adaptation every time a signal indicating that the position where the mobile station 30 exists is correct is received. For example, when the position estimation device 10 receives a signal indicating that the position is correct a predetermined number of times, radio map adaptation may be performed collectively based on observation data acquired so far. In addition, for example, radio map adaptation may be performed in batches based on observation data acquired so far at predetermined intervals or at arbitrary timings.

  Further, even when the accepting unit 33 of the mobile station 30 accepts an operation indicating that the position of the mobile station 30 is correct, the adaptation unit 16 determines the radio field strength between the mobile station 30 and the fixed station 20. If the magnitude of the difference between the observation data, which is the measurement value, and the radio map is larger than a predetermined size, the radio map need not be adapted. Thereby, even when the position of the mobile station 30 is correct, the radio map is not adapted by the observation data having a large deviation from the radio map, so that a decrease in the performance of the radio map can be suppressed.

  FIG. 9 shows the case where the mobile station 30 is in the position notified by the notification unit 15 and the correct button 33a is pressed. However, if the mobile station 30 is not in the position notified by the notification unit 15, the position estimation is not correct, so the user who has found the mobile station 30 is provided in the mobile station 30 as shown in FIG. The incorrect answer button 33b is pressed. At this time, since the mobile station 30 notifies the presence of the mobile station 30 itself, the user can easily find the mobile station 30.

  When the incorrect answer button 33 b is pressed, the mobile station 30 transmits a signal indicating that the position of the mobile station 30 is not correct to the position estimation device 10 via the fixed station 20.

  When the position estimation apparatus 10 receives a signal indicating that the position where the mobile station 30 exists is not correct, the position estimation apparatus 10 does not adapt the radio map.

[8. Radio map adaptation]
Here, the adaptation of the radio map in the adaptation unit 16 will be described with reference to FIG.

  FIG. 10 is a diagram illustrating an image of radio map adaptation. As shown in FIG. 10, the solid line, the alternate long and short dash line, and the dotted line respectively indicate the probability distribution of radio field intensity of the radio map before adaptation, the observation data, and the radio map radio wave after adaptation at position A2 in FIG. 3. It represents the probability distribution of intensity.

  The probability distribution of the observation data shown in FIG. 10 is distributed at a position where the radio field intensity is larger than the probability distribution of the radio field intensity of the radio map before adaptation due to the fluctuation of the radio field intensity. Assume that position estimation is performed using this observation data, and for example, the correct position is estimated this time. However, even if position estimation is performed in this state in the future, there is a high possibility that position estimation will fail due to a large difference in probability distribution between the radio map and observation data. Therefore, radio map adaptation is performed based on observation data. That is, the distribution of the radio wave intensity before adaptation is shifted in the direction of the observation data fluctuated due to the environmental change, and becomes the distribution of the radio wave intensity after adaptation considering the environmental fluctuation. This reduces the possibility that the estimation will fail in future position estimation.

  The radio map adaptation algorithm may be a general algorithm. For example, when a probabilistic radio map is used as in the present embodiment, MAP (Maximum A Poster) adaptation or MLLR (Maximum Likelihood Linear Regression) adaptation can be used. For example, when adapting the average of the radio map using MAP adaptation, specific adaptation of the radio map is performed by the procedure shown in the following Equation 3. The following equation 3 is an equation representing the average of the radio map after adaptation.

Here, r _t represents the radio wave intensity measured at the t-th of T times repeatedly measured, α and τ represent parameters of the prior distribution, and μ ₀ represents the average of the radio map before adaptation.

  Instead of the MAP adaptation method described above, the raw value of the radio field intensity measured in advance when creating the radio map is retained, and observation data is added or overwritten there to create a probability distribution each time. The radio map may be adapted by correcting it. Further, a radio wave intensity raw value may be virtually generated by resampling from the radio map after adaptation, and may be retained. In this case, the radio map can be adapted to a position estimation method using a radio map that is not based on a probability distribution such as SVM (Support Vector Machine) or k-NN (k-Nearest Neighbor).

  The position estimation device 10 that has received a signal indicating that the position where the mobile station 30 exists is correct performs adaptation of the radio map of the position corresponding to the position where the mobile station 30 exists based on the observation data. Not limited to this. For example, when a certain position is associated with at least one other position, and the position where the mobile station 30 exists is one of the associated positions, adaptation of the entire associated position May be performed. Note that the association between a certain position and at least one other position may be manually specified in consideration of a physical boundary such as a wall. The association of the position of the radio map may be automatically determined by clustering such as k-means or EM (Expectation-Maximization) algorithm.

  The position association may be performed only once when the position estimation system 1 is introduced, or may be performed each time the radio map is adapted. When the association is performed every time the radio map is adapted, the optimum association according to the actual change in the radio wave environment is appropriately performed, so that the effect of the adaptation can be further improved. Further, the position association may be performed at an arbitrary timing.

[9. Experimental result]
In addition, an experimental result of the position estimation of the mobile station 30 when the radio map is adapted according to the present embodiment will be described.

  First, when the position of the mobile station 30 is estimated without radio map adaptation when there is radio wave fluctuation due to environmental fluctuations, the estimated position and the position where the mobile station 30 was actually located are calculated. The error was 3.6m. On the other hand, when the radio map is adapted by MAP adaptation, the error between the estimated position and the actual position of the mobile station 30 is 2.1 m, and the position estimation error is 1.5 m. Improved.

[10. effect]
In this way, in position estimation system 1 and mobile station 30 in the present embodiment, the user inputs whether or not the position of the article notified from position estimation system 1 is correct, so the user goes to pick up the article. Then observation data is collected. In other words, it is not necessary to collect observation data separately except for system operation. Moreover, since the estimated position of the mobile station 30 is actually confirmed by the user to be associated with the observation data, it is possible to improve the performance of radio map adaptation. Therefore, in the present embodiment, observation data collection and radio map adaptation can be performed efficiently.

(Modification of the embodiment)
Although the position estimation system of the present invention has been described based on the embodiment, the present invention is not limited to this embodiment. Unless it deviates from the meaning of the present invention, various modifications conceived by those skilled in the art are applied to this embodiment, and forms constructed by combining components in different embodiments are also included in the scope of the present invention. It is.

  For example, in the above-described embodiment, an example in which the mobile station 30 receives radio waves from each AP has been described, but the present invention is not limited thereto. For example, each AP may receive radio waves from the mobile station 30. In this configuration, a radio map in each AP when the mobile station 30 is arranged at a plurality of predetermined positions may be created, and the probability distribution of the radio field intensity from the mobile station 30 measured in each AP The likelihood may be calculated from the radio map in each AP, and the position of the mobile station 30 may be estimated. In this case, the observation data generation unit 32 is provided in the fixed station 20. Further, for example, the mobile station 30 may receive radio waves from each AP, and each AP may receive radio waves from the mobile station 30, and the position of the mobile station 30 may be estimated based on both radio field strengths. . In this case, the observation data generation unit 32 is provided in both the fixed station 20 and the mobile station 30.

  Further, in the above embodiment, the mobile station 30 is a wireless tag, and the mobile station 30 that is a wireless tag is attached to an article that does not have a communication function. Not exclusively. For example, when the article whose position is estimated is a notebook PC or the like, since the notebook PC originally has a communication function and a user interface, it is not necessary to attach the mobile station 30 as a wireless tag. Therefore, the notebook PC can become the mobile station 30 only by installing software for estimating the position of the notebook PC.

  Moreover, in the said embodiment, although the designation | designated part 12 and the notification part 15 were each provided with input devices, such as a keyboard, a numeric keypad, or a touch panel, it is not restricted to this. For example, if the input of the search instruction by the designation unit 12 and the input of the notification instruction by the notification unit 15 can be recognized, the position estimation device 10 may have only one input device such as a keyboard, a numeric keypad, or a touch panel. Furthermore, if the input device is a touch panel, the notification unit 15 can notify the position of the mobile station 30 estimated by the position estimation unit 13 by displaying the touch panel. That is, the position estimation device 10 may include one touch panel as an input device and a display device.

  Moreover, in the said embodiment, although the position estimation apparatus 10 was provided with the designation | designated part 12 and the notification part 15, it is not restricted to this. For example, a mobile terminal such as a smartphone or a tablet may include a designation unit and a notification unit. The designation unit and the notification unit of the mobile terminal include an input / output device such as a touch panel. The designation unit designates the mobile station 30 selected on the touch panel, and further transmits an observation data generation instruction for the designated mobile station 30 to the communication unit 14 of the position estimation apparatus 10. That is, the portable terminal causes the position estimation device 10 to search for the mobile station 30 attached to the article to be searched by selecting the article that the user wants to search from the touch panel. In addition, the notification unit displays the notified position of the mobile station 30 on the touch panel, and further transmits a notification instruction to the mobile station 30 to the communication unit 14 when a notification instruction is input to the touch panel. That is, the user is notified of the position of the article affixed to the mobile station 30 estimated by the display on the touch panel, and can select a notification instruction to the mobile station 30 affixed to the article displayed on the touch panel. Therefore, for example, the user can go to pick up the article to which the mobile station 30 that has been notified is attached while viewing the notified position of the article on the mobile terminal. That is, even if the user forgets the position of the article notified on the way to take the article, the position of the article can be confirmed by looking at the display on the mobile terminal. Further, the mobile terminal may directly communicate with the mobile station 30 such as a search instruction, a notification instruction, and a position notification.

  Moreover, in the said embodiment, although the alerting | reporting part 34 alert | reported when the mobile station 30 received the alerting | reporting instruction | indication, it is not restricted to this. For example, the notification unit 34 may notify when the mobile station 30 receives an instruction to generate observation data. In this case, the notification unit 15 of the position estimation device 10 may not include an input unit such as a keyboard, a numeric keypad, or a touch panel to which a notification instruction is input.

  Moreover, in the said embodiment, although the position estimation apparatus 10 and the fixed station 20 were set as a different body, it is not restricted to this. For example, the fixed station 20 may include the position estimation device 10. In this configuration, wireless communication between the communication unit 14 and the communication unit 21 is not necessary, and the communication unit 14 and the communication unit 31 may directly transmit and receive signals. In this configuration, the number of position estimation devices 10 may not be one, and each AP may include the position estimation device 10.

  In the above embodiment, the fixed AP 20 includes the first AP 20a, the second AP 20b, and the third AP 20c, but is not limited thereto. The fixed station 20 may be one or two, and may be four or more.

  In the above embodiment, the adaptation unit 16 of the position estimation apparatus 10 performs radio map adaptation when the reception unit 33 receives an operation indicating that the position of the mobile station 30 is not correct. Not limited to this. In addition, the reception unit 33 may further receive an operation of inputting the correct position of the mobile station 30 that has been notified of the presence by the notification unit 34. For example, when the accepting unit 33 accepts an operation indicating that the position of the mobile station 30 is not correct, the adapting unit 16 of the position estimation apparatus 10 receives the correct position of the mobile station 30 received by the accepting unit 33, and The radio map may be adapted based on observation data that is a measurement value of the radio field intensity between the mobile station 30 and the fixed station 20. That is, when the mobile station 30 is not in the position notified by the notification unit 15, the mobile station 30 notifies its own existence to the surroundings, so that the user discovers the mobile station 30 in another position. Can do. Therefore, the user can know the correct position of the mobile station 30. When the user inputs the correct position of the mobile station 30 to, for example, the numeric keypad 33c that has accepted user authentication, the mobile station 30 may transmit the correct position information. The receiving unit 33 may include an input unit such as a touch panel, and the user may input the correct position of the mobile station 30 using the touch panel. Then, the adaptation unit 16 may perform radio map adaptation based on the correct position and observation data of the mobile station 30 received by the communication unit 14. Even if the reception unit 33 receives an operation indicating that the position of the mobile station 30 is not correct, and the communication unit 14 receives the correct position of the mobile station 30, the radio map must not be adapted. Also good. Specifically, when the communication unit 14 receives the correct position of the mobile station 30, the adaptation unit 16 receives the observation data that is a measurement value of the radio field strength between the mobile station 30 and the fixed station 20 and the correct position. If the magnitude of the deviation from the radio map is larger than a predetermined size, the radio map need not be adapted. Thereby, even when the correct position of the mobile station 30 is input to the user, the radio map is not adapted to the observation data having a large deviation from the radio map, thereby suppressing the deterioration of the performance of the radio map. Can do.

  Moreover, in the said embodiment, although the alerting | reporting part 34 was a speaker, it is not restricted to this. For example, the notification unit 34 may be a light emitting element such as an LED, a vibrator that generates vibration, a display, or a combination thereof. Thereby, the notification unit 34 performs notification that can be easily recognized by the user by notification using an alarm or voice, notification using characters using a display, notification using vibration, notification using blinking light, or the like. Therefore, the user can easily find the mobile station 30.

  Moreover, in the said embodiment, although the reception part 33 was provided with the correct answer button 33a, the incorrect answer button 33b, and the numeric keypad 33c, it is not restricted to this. For example, the reception unit 33 may be a touch panel or a voice input device by voice recognition. Further, when the reception unit 33 is a voice input device based on voice recognition, the reception unit 33 receives a voice when receiving an operation indicating whether the position of the mobile station 30 estimated by the position estimation unit 13 is correct. Authentication by recognition may be requested.

  Moreover, in the said embodiment, although the memory | storage part 11 is provided in the position estimation apparatus 10, it is not restricted to this. For example, it may be provided in an arbitrary communication device such as a fixed station 20, a mobile station 30, or a server on a communication network in which the position estimation device 10 is included.

  Moreover, in the said embodiment, although the wireless communication by wireless LAN was employ | adopted, it is not restricted to this. For example, you may employ | adopt the radio | wireless communication which estimates a position based on radio wave intensity | strengths, such as infrared rays, an ultrasonic wave, and Bluetooth (trademark).

  Further, the position of the mobile station 30 is not limited to being estimated in two dimensions, but may be estimated in three dimensions.

  The present invention can be used to estimate the position of a mobile station with respect to a fixed station by wireless communication.

DESCRIPTION OF SYMBOLS 1 Position estimation system 10 Position estimation apparatus 11 Storage part 12 Designation part 13 Position estimation part 14, 21, 31 Communication part 15 Notification part 16 Adaptation part 20 Fixed station 20a 1st AP
20b Second AP
20c 3rd AP
30 Mobile Station 32 Observation Data Generation Unit 33 Reception Unit 33a Correct Answer Button 33b Incorrect Answer Button 33c Numeric Keypad 34 Notification Unit

Claims (6)

A position estimation system for estimating a position of a mobile station with respect to at least one fixed station,
Radio map showing frequency distribution of radio field intensity at each of the plurality of positions , created by the position estimation system repeatedly measuring the radio field intensity between the mobile station and the fixed station for each of a plurality of positions A storage unit for storing
A designation unit for designating the mobile station whose position is estimated;
The position of the mobile station is estimated by comparing the radio map with a measured value of the radio field intensity obtained by measuring the radio field intensity between the mobile station and the fixed station specified by the specifying unit. A position estimation unit;
A notification unit for notifying the position of the mobile station estimated by the position estimation unit;
A reception unit that receives an operation indicating whether or not the position of the mobile station estimated by the position estimation unit is correct;
An adapting unit that performs adaptation, which is a process of updating the radio map, based on the measurement value of the radio field intensity when the accepting unit accepts an operation indicating that the position of the mobile station is correct Position estimation system. Furthermore, a notification unit for reporting the presence of the mobile station,
The accepting unit further accepts an operation of inputting a correct position of the mobile station informed of the presence by the notifying unit,
When the accepting unit accepts an operation indicating that the position of the mobile station is not correct, the adapting unit further receives the correct position of the mobile station received by the accepting unit, the measured value of the radio field intensity, The position estimation system according to claim 1, wherein adaptation of the radio map of the correct position is performed based on. 3. The position estimation system according to claim 1, wherein the adaptation unit does not adapt the radio map if the magnitude of the difference between the measured value of the radio wave intensity and the radio map is larger than a predetermined magnitude. . The position estimation according to any one of claims 1 to 3, wherein the reception unit requests authentication when receiving an operation indicating whether or not the position of the mobile station estimated by the position estimation unit is correct. system. A position estimation method for estimating a position of a mobile station with respect to at least one fixed station,
A designation step for designating the mobile station whose position is to be estimated;
A radio map that stores in advance a radio field strength measurement value obtained by measuring the radio field strength between the designated mobile station and the fixed station, and for each of a plurality of positions, position created by repeatedly measures the radio wave intensity, by matching the radio map showing the frequency distribution of the radio wave intensity in each of the plurality of positions, for estimating the location of the mobile station between the fixed station An estimation step;
A notification step of notifying the estimated position of the mobile station;
An accepting step of accepting an operation indicating whether or not the estimated position of the mobile station is correct;
An adaptation step of performing adaptation, which is a process of updating the radio map based on the measurement value of the radio field intensity when an operation indicating that the position of the mobile station is correct is received.   A position estimation apparatus in a position estimation system for estimating a position of a mobile station with respect to at least one fixed station,
  Radio map showing frequency distribution of radio field intensity at each of the plurality of positions, created by the position estimation system repeatedly measuring the radio field intensity between the mobile station and the fixed station for each of a plurality of positions A storage unit for storing
  A designation unit for designating the mobile station whose position is estimated;
  The position of the mobile station is estimated by comparing the radio map with a measured value of the radio field intensity obtained by measuring the radio field intensity between the mobile station and the fixed station specified by the specifying unit. A position estimation unit;
  A notification unit for notifying the position of the mobile station estimated by the position estimation unit;
  When the mobile station receives an operation indicating whether or not the position of the mobile station estimated by the position estimation unit is correct, information indicating whether or not the position of the mobile station is correct is received from the mobile station. A communication unit to receive,
  An adaptation unit that performs adaptation, which is a process of updating the radio map, based on the measurement value of the radio field intensity when the communication unit receives information indicating that the position of the mobile station is correct
  Position estimation device.

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