JP2016065741A - Position estimation device and position estimation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position estimation device improving a measurement accuracy, while reducing a time-variant followability.SOLUTION: A position estimation device 102 includes: a storage part 14 for storing an assumed high-order list 14b showing a combination of n pieces from a top of a reception level assumed at each measurement point of the space within a transmitter, and installation position information 14a showing an installation position of the transmitter; a reception part 10 for receiving a signal from the transmitter; and a position estimation part 12 for obtaining a second target time in which a combination of the transmitters corresponding to high-order N pieces is in coincidence with a combination of the assumed high-order list 14b in an average level of the reception from the first target time to the second target time going back in the past, and estimating the position in the first target time based on an average level from the first target time to the second target time and the setting position information 14a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a position estimation device and a position estimation program for estimating the position of a device based on a signal reception level.

  In recent years, a technique for estimating the current position of a terminal based on received radio wave intensity (hereinafter referred to as “reception level”) from radio transmitters such as a plurality of beacons installed in a space has been used. In such positioning technology that uses the received level, fluctuations other than the attenuation over distance occur due to fading and noise such as reflection (multipath) and interference, and the estimated current as a result. There was a risk of errors in position.

  In view of this, a technique for suppressing the influence of fading and the like in positioning and improving positioning accuracy by using an average level obtained by averaging the reception levels of radio waves received at a plurality of timings is disclosed (for example, Patent Documents). 1).

Japanese Patent Laid-Open No. 11-178041

  However, when positioning using the average level of the received signal, if the period for averaging the received level is lengthened and the number of received data used for averaging is increased, the position at the current time can be determined when the terminal is moving. It will not be reflected in real time, and the time tracking of the positioning result will be reduced. On the other hand, if the averaging period is shortened, the influence of fading cannot be sufficiently suppressed.

  Therefore, an object of the present invention is to improve the positioning accuracy while setting a reasonable period when averaging the reception level and suppressing a decrease in temporal followability.

  One aspect of the present invention is a position estimation device that estimates a position in the space based on reception levels from a plurality of signal transmitters installed in the space, wherein the space of the plurality of signal transmitters An assumed upper list indicating combinations of N (where N is 2 or more) from the highest reception level assumed at each positioning point, and installation position information indicating the installation positions of the plurality of signal transmitters are stored. A higher level in a smoothing value obtained from a storage unit, a receiving unit that receives signals from the plurality of signal transmitters, and a reception level for each signal transmitter from a first focused time to a second focused time that goes back in the past The combination of the signal transmitters corresponding to N is obtained for the second attention time that matches any combination of the assumed upper list, and from the first attention time to the matching second attention time. A position estimation section for estimating a position in the first time of interest based on the smoothed value and the installation position information of the reception level for each serial signal transmitter, a position estimation device, characterized in that it comprises a.

  Another aspect of the present invention is a position estimation program for estimating a position in the space based on reception levels from a plurality of signal transmitters installed in the space, and the computer is traced back to the past from the first time of interest. A combination of the signal transmitters corresponding to the top N smoothing values obtained from the reception levels of the signal transmitters up to the second target time is assumed at each positioning point in the space among the plurality of signal transmitters. The second attention time that matches any combination in the assumed upper list indicating N combinations (where N is 2 or more) from the highest received level is obtained, and the first matching time is determined from the first attention time. 2 The position at the first time of interest based on the smoothed value of the reception level for each signal transmitter up to the time of interest and the installation position information indicating the installation positions of the plurality of signal transmitters. A position estimation unit for estimating the a position estimating program, characterized in that it comprises a.

  Here, it is preferable that the assumed upper list is set based on an installation position of the signal transmitter and a position of the positioning point.

  Moreover, it is preferable that the assumed upper list is further set based on the position and shape of an obstacle existing in the space.

  In addition, the storage unit further stores a preliminary list indicating M combinations (where M is greater than N) from the top of the reception level assumed at each positioning point in the space among the plurality of signal transmitters. When the combination of the signal transmitters corresponding to the top N smoothing values does not match any combination of the assumed top list, the position estimation unit corresponds to the top M smoothing values. The second attention time at which a combination of signal transmitters matches any combination of the preliminary list is obtained, and the reception level of each signal transmitter from the first attention time to the matching second attention time is determined. It is preferable to estimate the position at the first time of interest based on a smooth value and the installation position information.

  Another aspect of the present invention is a position estimation device that estimates a position of a signal transmitter existing in the space based on reception levels in a plurality of signal receivers installed in the space, the plurality of signal receivers An assumed upper list indicating combinations of N (where N is 2 or more) from the highest reception level assumed at each position of the signal transmitter in the space, and installation positions of the plurality of signal receivers. A storage unit that stores the installed position information, a communication unit that communicates with the plurality of signal receivers, and a reception level for each signal receiver from the first target time to a second target time that goes back in the past. The second target time when the combination of the signal receivers corresponding to the top N smoothing values matches any combination of the assumed upper list is obtained, and the second matching time is determined from the first target time. A position estimation unit comprising: a position estimation unit configured to estimate a position at the first target time based on a smooth value of a reception level for each signal receiver up to an eye time and the installation position information. .

  Another aspect of the present invention is a position estimation program for estimating the position of a signal transmitter existing in a space based on reception levels in a plurality of signal receivers installed in the space, and the computer is first focused on A combination of the signal receivers corresponding to the top N in the smoothed value of the reception level for each signal receiver from the time to the second target time traced back in the past is the signal in the space among the plurality of signal receivers. Obtaining the second time of interest that matches any combination in the assumed upper list indicating the combinations of N (where N is 2 or more) from the highest reception level assumed at each position of the transmitter; Based on the smoothed value of the reception level for each signal receiver from the time of interest to the matching second time of interest and the installation position information indicating the installation positions of the plurality of signal receivers A position estimation section for estimating the position of the serial first time of interest, a position estimating program, characterized in that it comprises a.

  Here, it is preferable that the assumed upper list is set based on an installation position of the signal receiver and a position of the positioning point.

  Moreover, it is preferable that the assumed upper list is further set based on the position and shape of an obstacle existing in the space.

  In addition, the storage unit further stores a preliminary list indicating M combinations (where M is greater than N) from the top of the reception level assumed at each positioning point in the space among the plurality of signal receivers. When the combination of the signal receivers corresponding to the top N in the smooth value does not match any combination in the assumed top list, the position estimation unit (position estimation unit) The second target time in which the combination of the signal receivers corresponding to the number matches any combination in the preliminary list is obtained, and reception for each signal receiver from the first target time to the second target time is performed. It is preferable to estimate the position at the first time of interest based on a level smooth value and the installation position information.

  ADVANTAGE OF THE INVENTION According to this invention, the position estimation apparatus and position estimation program which improved the positioning precision can be provided, suppressing the fall of temporal followability.

It is a figure which shows the structure of the position estimation system in embodiment of this invention. It is a block diagram which shows the structure of the position estimation apparatus in embodiment of this invention. It is a figure which shows the example of registration of the installation position information in embodiment of this invention. It is a figure which shows the example of registration of the assumption high list | wrist in embodiment of this invention. It is a figure explaining the setting method of an assumption high rank list in an embodiment of the invention. It is a figure explaining the setting method of an assumption high rank list in an embodiment of the invention. It is a figure which shows the example of registration of the preliminary | backup list in embodiment of this invention. It is a figure which shows the example of registration of the reception level table in embodiment of this invention. It is a timing chart explaining the registration method of the reception level table and average level table in embodiment of this invention. It is a figure which shows the example of registration of the average level table in embodiment of this invention. It is a flowchart which shows the position estimation method in embodiment of this invention. It is a figure explaining the position estimation method in embodiment of this invention. It is a block diagram which shows the structure of the position estimation apparatus in a modification.

<System configuration>
A position estimation system 100 according to an embodiment of the present invention includes a position estimation device 102 and transmitters 104 (104a to 104j), as shown in FIG. The position estimation system 100 includes a plurality of transmitters 104, receives signals transmitted from the transmitters 104 by the position estimation device 102, and is based on the received signal strength (hereinafter referred to as “reception level”) of the received signals. Thus, the position of the position estimation device 102 is estimated.

  The transmitter 104 is installed in the space and includes signal transmission means for outputting a beacon signal. For example, the transmitter 104 is attached to a ceiling in a facility and transmits a beacon signal as a radio wave, a sound wave, or the like. As shown in FIG. 1, it is preferable that the transmitters 104 are periodically arranged so as to form an equilateral triangle when the arrangement points of the three transmitters 104 are connected.

  The beacon signal is a signal for acquiring various types of information including a position by receiving the position estimation apparatus 102. In the present embodiment, the beacon signal includes information that can specify the installation position in the space of the transmitter 104 of the transmission source. For example, a transmitter received by referring to a database in which a transmitter identifier is associated with an installation position of the transmitter 104 by including a transmitter identifier that identifies the transmitter 104 in the beacon signal. The installation position of the sender's transmitter 104 can be acquired from the identifier.

  As shown in the functional block diagram of FIG. 2, the position estimation device 102 includes a reception unit 10, a position estimation unit 12, a storage unit 14, an input unit 16, and an output unit 18. The position estimation apparatus 102 can be realized by executing a position positioning program using a general computer.

  The receiving unit 10 receives a beacon signal from the transmitter 104. When the beacon signal is a radio wave, the receiving unit 10 includes a radio wave receiver, an amplifier, and the like. The received beacon signal is input to the position estimation unit 12.

  The position estimation unit 12 functions as means for estimating the position of the position estimation device 102 based on the beacon signal received from the transmitter 104. The position estimation unit 12 includes a reception level measurement unit 12a, an average calculation unit 12b, a validity determination unit 12c, and a position calculation unit 12d.

  The reception level measuring means 12a is a means for measuring the signal strength (reception level) of the signal (beacon signal) received from the transmitter 104. When the signal from the transmitter 104 is a radio wave, the amplitude of the received radio wave is detected as a reception level.

  The average calculation means 12b uses a certain time as the first focus time, and each transmission measured by the reception level measurement means 12a over the average period from the first focus time to the second focus time in the past from the first focus time. This is means for performing processing for calculating an average value (average level) obtained by averaging the reception level of the signal from the transmitter 104 for each transmitter 104. The first attention time, the second attention time, the setting method of the average period, and the reception level averaging method will be described later.

  The validity determination means 12c is a means for determining whether or not the average level is a reasonable value as data used for position estimation. Specifically, the validity determination unit 12c is configured to select the highest N of the average levels of the signals from the transmitters 104 averaged over the average period in the average calculation unit 12b (where N is 2). It is determined whether or not the combination of the transmitters 104 corresponding to the above) matches any combination registered in the assumed upper list 14b described later. If there is a combination of transmitters 104 that matches the assumed upper list 14b, it is assumed that the reception level of the signal received from each transmitter 104 is appropriate as data used for position estimation of the position estimation device 102, and the average The position of the position estimation device 102 is estimated based on the average level of the signal over the period. If the combination of the transmitters 104 that match the assumed upper list 14b does not match, the reception level of the signal received from each transmitter 104 is not valid as the data used for estimating the position of the position estimation device 102. The position of the position estimation device 102 is not estimated based on the average level of the signal over the average period.

  When there is no combination of the transmitters 104 that matches the assumed upper list 14b, the validity determination unit 12c determines the average level of the signal from each transmitter 104 averaged over the average period in the average calculation unit 12b. It may be determined whether the combination of the transmitters 104 corresponding to the top M pieces (where M is greater than N) matches any combination registered in the backup list 14c described later. If there is a combination of transmitters 104 that matches the preliminary list 14c, it can be said that the reception level of the signal received from each transmitter 104 is reasonable to some extent as data used for position estimation of the position estimation device 102. The position of the position estimation device 102 is estimated based on the average level of the signal over the average period. If there is no combination of the transmitters 104 that matches the preliminary list 14c, it can be said that the reception level of the signal received from each transmitter 104 is not valid as data used for position estimation of the position estimation device 102, and the average period The position of the position estimation device 102 is not estimated based on the average level of the signal over the range.

  The position calculation unit 12d determines the space of the position estimation device 102 based on the average level of the received signal from each transmitter 104 from the first target time to the second target time determined to be appropriate by the validity determination unit 12c. It is a means to perform the process which estimates the position in the inside. A method of estimating the position of the position estimation device 102 in the position calculation means 12d will be described later.

  The storage unit 14 includes a memory device such as a semiconductor memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit 14 stores at least installation position information 14a, an assumed upper list 14b, a reserve list 14c, a reception level table 14d, and an average level table 14e.

  As shown in FIG. 3, the installation position information 14a is a database in which the installation positions of the transmitters 104 in the space are registered. In the example of FIG. 3, the position (latitude and longitude) in the plane associated with each transmitter 104 is registered, but three-dimensional position information may be registered by adding information such as altitude. Further, not only latitude, longitude, and altitude, but position information including coordinate values (x, y, z) based on a certain position in a three-dimensional space may be registered.

  As shown in FIG. 4, the assumed upper list 14 b is a database indicating combinations of N transmitters 104 from the highest reception level (where N is 2 or more) at the reception level assumed at each positioning point in the space. FIG. 4 shows an example where N is 3.

  The assumed upper list 14 b can be set from the actual measurement value of the reception level of the signal received by the position estimation device 102 from each transmitter 104. That is, the reception level of the signal by the position estimation device 102 is measured in advance for each positioning point that can receive a signal from any of the transmitters 104, and the reception level of the actual measurement result is expressed as “the reception level assumed at each positioning point in space. " Then, N transmitters 104 are extracted from the higher one in the actual measurement result, and a combination of these N extracted transmitters 104 is registered as one set in the assumed upper list 14b. As described above, the assumed upper list 14b can be set by actually measuring the reception level at the representative positioning points in the space and registering the combinations of the N extracted transmitters 104, respectively.

  Also, the assumed upper list 14b selects N transmitters 104 that are geometrically closest to each positioning point in the space, and the combination of the selected N transmitters 104 is assumed as the assumed upper list 14b. You may register as For example, in FIG. 5, the three transmitters 104 closest to the positioning point P1 are a transmitter 104a, a transmitter 104b, and a transmitter 104e. Therefore, the combination of the transmitter 104a, the transmitter 104b, and the transmitter 104e is registered as a set in the assumed upper list 14b with respect to the positioning point P1. In this way, the assumed upper list 14b can be set by a combination of the three transmitters 104 closest to the representative positioning point in the space. As shown in FIG. 5, when the transmitter 104 is regularly arranged in a space in a substantially regular polygon (regular triangle in the figure), the transmitter 104 that forms the apex of the regular polygon is used. The assumed upper list 14b can be set by combination. That is, as shown in FIG. 5, when regularly arranged in an equilateral triangle shape, the transmitters 104 that form the three vertices constituting each triangle are made into a set of combinations, and an assumed upper list 14b from each combination. Can be set.

  As shown in FIG. 6, when there is an obstacle 106 such as a wall or a fixture existing in the space, it is preferable to set the assumed upper list 14b in consideration of the influence of the obstacle 106 on the arrival of the signal. It is. For example, considering the area where signals such as radio waves cannot pass through the area of the obstacle 106, the distance from the positioning point P2 to the transmitter 104e is not the straight line distance but the distance when the obstacle 106 is detoured is the most from the positioning point P2. It is preferable to select N transmitters 104 present in the vicinity. In FIG. 6, the three transmitters 104 that are linearly closest to the positioning point P2 are the transmitter 104e, the transmitter 104f, and the transmitter 104i. However, considering the detour distance, the three transmitters 104 that are closest to the positioning point P2 The transmitter 104 is a transmitter 104f, a transmitter 104i, and a transmitter 104j. Therefore, the combination of the transmitter 104f, the transmitter 104i, and the transmitter 104j is registered as a set in the assumed upper list 14b with respect to the positioning point P2.

  Further, a combination of N transmitters 104 that do not straddle the obstacle 106 linearly with the position estimation apparatus 102 may be set in the assumed upper list 14b. In addition, by performing a known radio wave propagation simulation using a three-dimensional model in consideration of the characteristics of the material of the obstacle 106, N transmissions from the higher one at the reception level assumed at each positioning point in space. The combination of the machines 104 may be obtained and the assumed upper list 14b may be set.

  As shown in FIG. 7, the preliminary list 14 c is a database indicating combinations of M (from which M is greater than N) from the top of the reception level assumed at each positioning point in the space among the plurality of transmitters 104. is there. FIG. 7 shows an example where M is 4. The preliminary list 14c can be set in the same manner as the assumed upper list 14b.

  Note that since the preliminary list 14c is for registering M combinations that are more than N from the top of the assumed reception level at each positioning point, the number of combinations in the preliminary list 14c is larger than that of the assumed upper list 14b. .

  As shown in FIG. 8, the reception level table 14d is a database for registering the reception level of the signal from each transmitter 104 received by the position estimation device 102 at each measurement timing. As shown in the timing chart of FIG. 9, every time a signal from each transmitter 104 is received by the position estimation device 102, the reception level is recorded in the reception level table 14d in order. As a result, the reception level table 14d indicates that the reception level of the signal from each transmitter 104 is the reception level S1, S2... At every measurement timing −t1, −t2. Are recorded in time series.

  As shown in FIG. 10, the average level table 14 e is a database that registers a temporal average value of reception levels at the position estimation device 102 at the measurement timing as an average level for each transmitter 104. For example, as shown in the timing chart of FIG. 9, when the averaging time (average period) is set to times T1, T2, T3,..., Past measurement timings -t1, -t2,-from the current time, respectively. Going back to t3..., average levels A1, A2,. For example, the average level A1 is the signal reception level S1 for each transmitter 104 at the latest measurement timing t1. The average level A2 is an average value of the reception level S1 at the measurement timing t1 and the reception level S2 at the measurement timing t2 for each transmitter 104. The average level A3 is an average value of the reception level S1 at the measurement timing t1 for each transmitter 104, the reception level S2 at the measurement timing t2, and the reception level S3 at the measurement timing t3. Similarly, average levels A4, A5... Can be calculated in the same manner.

  The average level can simply be an arithmetic average of the received levels. In this case, average level A1 = S1, average level A2 = (S1 + S2) / 2, average level A3 = (S1 + S2 + S3) / 3, and so on. The average level may be an average value considering time. In this case, average level A1 = {S1 * t1 + S2 * (T1-t1)} / T1, average level A2 = {S1 * t1 + S2 * (t2-t1) + S3 * (T2-t2)} / T2. .

  In this embodiment, the average value for each measurement timing t1, t2,... Is calculated as the average level by tracing the reception level of signals received at discrete measurement timings t1, t2,. However, the signal from each transmitter 104 may be continuously received, and a value obtained by continuously averaging the reception levels may be registered in the average level table 14e as an average level.

  In the present embodiment, in order to remove the influence of fading and the like from the reception level measured at the first time of interest, a simple average value (average level) of the reception level in the average period is used as the smoothing value in the present invention. It is used as. However, the present invention is not limited to this, and based on the reception level within a predetermined period from the first attention time to the second attention time in the past from the first attention time, the reception level from which the influence of fading or the like at the first attention time is removed. Any method may be used as long as it is an estimation method. For example, the average value may be obtained by using the measured reception level excluding a certain number of upper and lower data within the average period. Thereby, the influence of an extreme abnormal value can be eliminated. Further, a method of estimating the reception level from which the influence such as fading is removed without averaging may be used. For example, if the probability distribution for the received level from which the influence of fading or the like is removed is known for the measured received level, the probability distribution is obtained for each of the plurality of received levels at different measurement times, and over a predetermined period. By multiplying the probability values of these probability distributions, the reception level with the highest probability value can be used as the smooth value in the present invention.

  Furthermore, since the reception level at another time that is farther away from the first time of interest is more strongly affected by movement during that time, the reception level in which influences such as fading are removed in consideration of the influence of this movement May be estimated. For example, the average value may be obtained after multiplying the reception level at each measurement time by a coefficient that decreases as the distance from the first focus time increases. Alternatively, a probability distribution at another time may be obtained so that the variance increases as the distance from the first time of interest increases, and the reception level from which the influence of fading or the like is removed as described above may be estimated based on the probability distribution.

  The input unit 16 is used for a user to input a command or the like to the position estimation apparatus 102. The input unit 16 can be, for example, a character input device such as a keyboard or a pointing device such as a mouse. The output unit 18 is used to display the processing result of the position estimation device 102 to the user. The output unit 18 can be an image display device such as a display.

<Position estimation method>
Hereinafter, a position estimation method in the position estimation system 100 will be described with reference to the flowchart of FIG. In the following description, it is assumed that the history of past data of the reception level of the signal from each transmitter 104 measured by the position estimation device 102 is accumulated in the reception level table 14d.

  In the position estimation method according to the present embodiment, a process for estimating the position of the position estimation apparatus 102 at the first time of interest based on the reception level table 14d will be described. In the following description, the current time is set as the first time of interest. As a result, the position of the position estimation device 102 at the current time is estimated. The first time of interest is not limited to the current time, and a past time may be set as the first time of interest. For example, the process of estimating the position of the position estimation device 102 at the past time −t2 can be performed by setting the measurement timing −t2 of the reception level to the first time of interest.

  In step S10, an initial value of a period (average period) for averaging the reception levels stored as the reception level table 14d is set. The average period is a period from the first focus time to the second focus time at which the reception level of the received signal from each transmitter 104 is averaged in the average calculation means 12b. It is preferable that the initial value of the average period is a time until at least one past measurement timing is included from the first time of interest.

  In step S12, an average level calculation process is performed. The average calculation means 12b of the position estimation apparatus 102 calculates a value obtained by averaging the reception level for each transmitter 104 over the set average period as an average level and registers it in the average level table 14e.

  In step S14, combinations of transmitters 104 corresponding to the top N (N is 2 or more) are selected from the higher average value calculated in step S12.

  In step S16, it is determined whether or not the combination of transmitters 104 selected in step S14 matches any of the combinations of transmitters 104 registered in the assumed upper list 14b. The validity determination unit 12c of the position estimation apparatus 102 may include a combination corresponding to the combination of the transmitters 104 corresponding to the top N in the average level selected in step S14 in the assumed upper list 14b. The process proceeds to step S18, and if not, the process proceeds to step S20.

  In step S18, the position of the position estimation device 102 is estimated. The position calculation means 12d of the position estimation device 102 calculates the average level of each transmitter 104 from the current average period calculated in step S12, that is, from the first target time (current time) to the currently set second target time. Is used to estimate the position of the position estimation apparatus 102.

  A position estimation technique based on the average level from each transmitter 104, which is a conventional technique, can be applied to estimate the position of the position estimation apparatus 102. The average level of the signal from each transmitter 104 received by the position estimation device 102 is inversely proportional to the distance between each transmitter 104 and the position estimation device 102. Therefore, as shown in FIG. 12, based on the average level of the signal from each transmitter 104, the distance from the installation position of each transmitter 104 registered in the installation position information 14a to the position estimation device 102 (in FIG. 12, And the position P of the position estimation device 102 can be estimated based on the distance from at least three transmitters 104.

  The position estimation device 102 may estimate the position by using the average level of all transmitters 104 that can be received by the position estimation device 102 or from the transmitter 104 that can be received by the position estimation device 102. The average level of the selected transmitter 104 may be used. For example, the position of the position estimation device 102 may be estimated using the average level of the transmitter 104 selected in step S16 (or step S26 described later).

  When the position of the position estimation device 102 is estimated, information indicating the position of the position estimation device 102 is displayed on the output unit 18. Further, not only the position of the position estimation apparatus 102 but also the average level and average period used for position estimation may be output as an index of positioning accuracy. That is, an index indicating that the positioning accuracy is higher as the average level used for position estimation is larger or the average period is shorter may be output. Alternatively, has the position been estimated using the average level of the second target time that matches the assumed upper list 14b (step S16-Yes), or has the position been estimated using the average level of the second target time that matches the preliminary list 14c? You may display so that positioning accuracy may differ by (step S26-Yes). That is, when the position is estimated using the average level of the second attention time that matches the preliminary list 14c, an output indicating that the positioning accuracy is low may be performed.

  In step S20, processing for increasing the average period is performed. The average period for averaging the reception levels stored in the reception level table 14d is increased from the current value. In other words, the average period is increased by resetting the current second focus time to a past time and extending the period from the first focus time to the second focus time.

  In step S22, it is determined whether or not the average period is equal to or greater than the time limit Th1. If the average period newly set in step S20 is equal to or greater than the time limit Th1, the process proceeds to step S24, and if it is less than the time limit Th1, the process proceeds to step S12 and the process from step S12 is repeated. .

  In step S24, combinations of transmitters 104 corresponding to the top M (M is greater than N) from the higher average level calculated in step 12 are selected.

  In step S26, it is determined whether or not the combination of the selected transmitters 104 matches any of the combinations of the transmitters 104 registered in the backup list 14c. The validity determination unit 12c of the position estimation device 102 performs a step if the combination corresponding to the combination of the transmitters 104 corresponding to the highest M in the average level selected in step S24 is included in the preliminary list 14c. The process proceeds to S18, and if not, the process proceeds to step S28.

  In step S28, processing for increasing the average period is performed. Here, as in step S20, the period for averaging the reception levels stored in the reception level table 14d is increased from the current value.

  In step S30, it is determined whether or not the average period has reached the time limit Th2. If the average period newly set in step S28 is equal to or greater than the time limit Th2, the process proceeds to step S32. If it is less than the time limit Th2, the process proceeds to step S34.

  In step S32, processing when the positioning of the position estimation apparatus 102 fails is performed. In the present embodiment, a positioning failure flag is set. When the positioning failure flag is set, the position estimation device 102 may perform processing such as displaying information indicating that positioning has failed on the output unit 18. Alternatively, a process for causing the output unit 18 to display the position information estimated when the positioning was most recently succeeded is performed, or an average level is obtained in a preset average period, and a positioning result and a positioning error based on the average level are obtained. You may perform the process which displays the big thing on the output part 18. FIG.

  In step S34, an average level calculation process is performed. Similar to step S12, the average level of each transmitter 104 in the new average period set in step S28 is calculated. Thereafter, the process returns to step S24.

  As described above, the average period from the first target time to the second target time that goes back in the past is increased, and the average level of the received signal of each transmitter 104 in the average period corresponds to the highest N. The second attention time at which the combination of the transmitters 104 matches any combination in the assumed upper list 14b is obtained, and the average level and installation position information of each transmitter 104 in the average period from the first attention time to the second attention time. The position of the position estimation device 102 at the first time of interest can be estimated based on 14a.

  This makes it possible to flexibly set the average period according to the reception state of the signal without fixing the average period for obtaining the average level, and to obtain the average level in the average period in which a reasonable estimation result can be obtained. become able to. Therefore, it is possible to provide a position estimation system with high position accuracy and high time followability while suppressing the influence of fading and the like.

  If the combination of the transmitters 104 corresponding to the top N average level does not match any combination of the assumed upper list 14b, the combination of the transmitters 104 corresponding to the top M average level is any of the spare lists 14c. The position of the position estimation device 102 at the first time of interest is determined based on the average level of each transmitter 104 from the first time of interest to the second time of interest and the installation position information 14a. Can be estimated.

  Even when the average period is increased, the average level may not match the assumed upper list due to some environmental factors, and it is also assumed that the time followability is extremely lowered. However, the use of a spare list in which the number of combinations of the transmitters 104 is larger than that of the assumed upper list and the combination matching conditions are more relaxed can prevent the time followability from being extremely lowered due to environmental factors. it can.

<Example>
Hereinafter, as shown in FIG. 8, an example of the position estimation method in the present embodiment will be described in the case where the reception level from each transmitter 104 is recorded in the reception level table 14 d. In this embodiment, a case where the position of the position estimation device 102 at the current time is estimated will be described.

  In step S10, as shown in FIG. 9, a time T1 including the measurement timing -t1 one past from the current time as the first time of interest and not including the measurement timing -t2 is set as the initial value of the average period. . In this case, since only the reception level S1 at the measurement timing -t1 is the target of the averaging process, as shown in FIG. 10, the average level A1 of each transmitter 104 is the reception level of each transmitter 104 in the assumed upper list 14b. Matches S1.

  When N is set to 3, in step S14, combinations of transmitters 104a, 104c, and 104d corresponding to the top three are selected from the highest in the average level A1 of the assumed top list 14b. In step S16, it is determined whether or not the combination of the selected transmitters 104a, 104c, and 104d is registered in the assumed upper list 14b. If these combinations are not registered in the assumed upper list 14b, the process proceeds to step S20. Is migrated.

  In step S20, as shown in FIG. 9, a time T2 including the past measurement timing -t2 and not including the measurement timing -t3 from the first target time (current time) is set as a new average period. If this time T2 is less than the time limit Th1, the process returns to step S12, and the reception levels S1 and S2 of the transmitters 104 between the first target time (current time) and the time T2 are averaged. As shown in FIG. 10, the average level A2 of each transmitter 104 is registered.

  In step S14, a combination of transmitters 104a, 104b, and 104d corresponding to the top three is selected from the highest in the average level A2 of the assumed top list 14b. In step S16, it is determined whether or not the combination of the selected transmitters 104a, 104b, and 104d is registered in the assumed upper list 14b. If these combinations are registered in the assumed upper list 14b, the process proceeds to step S18. Is migrated. In step S18, the position of the position estimation device 102 is estimated based on the average level A2 of each transmitter 104.

  If the combination of transmitters 104 corresponding to the assumed upper list 14b is not selected even if the average period is increased until the time limit Th1 is reached, the number of transmitters 104 included in the combination is changed from N to M. It is increased and it is determined whether or not it matches the preliminary list 14c, and if it matches, the position of the position estimation device 102 is estimated using the average level at that time.

  In this way, the average level of the received signal from each transmitter 104 is calculated while going back from the time at which the position of the position estimation device 102 is estimated, and the upper combination of the average levels of each transmitter 104 is the assumed upper list. If it matches 14b or preliminary list 14c, it can be determined that the average level at that time is a reasonable value representing the reception level assumed at each positioning point in the space. Therefore, by estimating the position of the position estimation device 102 based on the average level of the transmitter 104 at that time, the correct position can be estimated without the influence of fading. On the other hand, it is possible to suppress an increase in the period during which the reception level is averaged, and it is possible to estimate the position in real time even when the position estimation apparatus 102 is moving. That is, it is possible to improve the positioning accuracy while setting a reasonable period when averaging the reception level and suppressing a decrease in temporal followability. It should be noted that the combination of transmitters 104 selected in the top N (or M) from the higher average level matches the combination of transmitters 104 registered in the assumed top list 14b (or backup list 14c). There may be a plurality of times of the second attention time. However, it is preferable that the second target time of the average level used for position estimation among them is the time closest to the first target time. As a result, the position can be estimated in the shortest average period in which a reasonable result is obtained, and a positioning result with good temporal followability can be obtained.

<Modification>
In the above embodiment, a mode has been described in which a plurality of transmitters 104 are arranged in the space and the position of the position estimation device 102 is estimated. However, as shown in FIG. 13, a plurality of receivers 108 are arranged in the space, It can also be set as the aspect which estimates the position of the certain transmitter 104 which exists in space.

  In this case, the position estimation device 102 includes a communication unit (not shown) that communicates with each receiver 108 via a wired or wireless network instead of the reception unit 10, and each receiver 108 receives the communication unit via the communication unit. The reception level of the beacon signal received from the transmitter 104 may be received and the reception level stored in the reception level table 14d. By similarly performing the various processes shown in FIG. 11 using the reception level table 14d, the position estimation apparatus 102 can perform the process of estimating the position of the transmitter 104.

  In the case of this modification, the transmitter 104 may be provided with the function of the position estimation device 102. That is, the transmitter 104 has the above-described communication unit, is connected to a plurality of receivers 108 via the communication unit 19 through a network, and receives beacon signals from the transmitters 104 received by each receiver 108. The level is received, and the reception level is stored as a reception level table 14d. Then, by performing the various processes shown in FIG. 11 in the same manner using the reception level table 14d, it is possible to estimate the position of itself (transmitter 104).

  DESCRIPTION OF SYMBOLS 10 Reception part, 12 Position estimation part, 12a Reception level measurement means, 12b Average calculation means, 12c Validity determination means, 12d Position calculation means, 14 Storage part, 14a Installation position information, 14b Assumed upper list, 14c Preliminary list, 14d Reception level table, 14e Average level table, 16 input unit, 18 output unit, 100 position estimation system, 102 position estimation device, 104 transmitter, 106 obstacle, 108 receiver.

Claims (5)

A position estimation device that estimates a position in the space based on reception levels from a plurality of signal transmitters installed in the space,
Among the plurality of signal transmitters, an assumed high-order list indicating combinations of N (where N is 2 or more) from the highest reception level assumed at each positioning point in the space, and installation of the plurality of signal transmitters A storage unit for storing installation position information indicating a position;
A receiver for receiving signals from the plurality of signal transmitters;
Any combination of the signal transmitters corresponding to the top N in the smooth value obtained from the reception level of each signal transmitter from the first target time to the second target time retroactive to the past is one of the assumed upper lists. The second attention time that matches the combination is obtained, and the first attention is based on the smoothed value of the reception level for each signal transmitter from the first attention time to the matching second attention time and the installation position information. A position estimation unit for estimating a position at a time;
A position estimation apparatus comprising: The position estimation apparatus according to claim 1,
The position estimation apparatus, wherein the assumed upper list is set based on an installation position of the signal transmitter and a position of the positioning point. The position estimation device according to claim 2,
The assumed estimation list is further set based on the position and shape of an obstacle present in the space. The position estimation device according to any one of claims 1 to 3,
The storage unit further stores a preliminary list indicating M combinations (where M is greater than N) from the highest reception level assumed at each positioning point in the space among the plurality of signal transmitters,
When the combination of the signal transmitters corresponding to the top N in the smooth value does not match any combination in the assumed upper list, the position estimating unit transmits the signal corresponding to the top M in the smooth value. The second attention time at which a combination of machines matches any combination of the preliminary list is obtained, and a smoothing value of the reception level for each signal transmitter from the first attention time to the matching second attention time And a position estimation device that estimates a position at the first time of interest based on the installation position information. A position estimation device for estimating a position of a signal transmitter existing in the space based on reception levels in a plurality of signal receivers installed in the space,
An assumed upper list indicating combinations of N (from N to 2 or higher) combinations of reception levels assumed at each position of the signal transmitter in the space among the plurality of signal receivers; and the plurality of signals A storage unit that stores installation position information indicating an installation position of the receiver;
A communication unit communicating with the plurality of signal receivers;
The combination of the signal receivers corresponding to the top N in the smoothed value of the reception level for each signal receiver from the first target time to the second target time that goes back in the past becomes any combination in the assumed upper list. The matching second attention time is obtained, and the smoothing value of the reception level for each signal receiver from the first attention time to the matching second attention time and the installation position information are used. A position estimation unit for estimating a position;
A position estimation apparatus comprising: