JP6805880B2 - Mobile terminals, methods and mobile communication systems - Google Patents

Description

The present invention relates to mobile terminals, methods and mobile communication systems.

In the near future, technology for estimating the position of a user of a mobile terminal is being actively used. As a position estimation technique, for example, a technique called PDR (Pedestrian Dead Reckoning) is known. PDR is a technique for estimating the user's position by accumulating the rotation angle calculated from the angular velocity sensor and the movement distance calculated from the acceleration sensor. In this regard, Patent Document 1 discloses a car navigation device that estimates the current position of a vehicle.

In the above-mentioned PDR, errors in position estimation are also accumulated, so it is useful to correct (update) the reference position using, for example, the coordinates of a fixed node.

Japanese Unexamined Patent Publication No. 2012-126091

However, the installation of fixed nodes has space and cost limitations. If the installation density of fixed nodes is insufficient, it is difficult for mobile terminals to estimate the position with sufficient accuracy.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved one capable of updating the reference position at an opportunity other than communication with a fixed node. To provide mobile terminals, methods and mobile communication systems.

In order to solve the above problem, according to a certain viewpoint of the present invention, it is a mobile terminal, and the position information of the mobile terminal calculated by accumulating the amount of change in the position of the mobile terminal at a reference position is acquired. The position information acquisition unit, the reliability acquisition unit that acquires the reliability information of the position information of the mobile terminal based on the elapsed time from the update of the reference position, and the position of the other mobile terminal from the other mobile terminal. The other terminal information acquisition unit that acquires the information and the reliability information of the position information of the other mobile terminal, the reliability information of the position information of the mobile terminal, and the reliability information of the position information of the other mobile terminal. The reliability acquisition unit includes a control unit that controls the update of the reference position using the position information of the other mobile terminal, and the reliability acquisition unit has a set time set at the time of updating the reference position. , A mobile terminal is provided that acquires the reliability information based on the total of the elapsed time from the update of the reference position .

The control unit may set the set time by using the reliability information of the position information of the other mobile terminal in addition to updating the reference position.

The mobile terminal further includes a fixed node information acquisition unit that acquires the position information of the fixed node from the fixed node, and the control unit updates the reference position using the position information of the fixed node and sets the setting. The time may be set to a predetermined value.

The control unit determines whether or not the reception strength of the signal received from the other mobile terminal exceeds the threshold value, and based on the reception strength of the signal received from the other mobile terminal exceeds the threshold value. The update of the reference position may be controlled by using the position information of the other mobile terminal.

The control unit is based on the fact that the reliability indicated by the reliability information of the position information of the other mobile terminal is higher than the reliability indicated by the reliability information of the position information of the mobile terminal. You may control the update of the reference position using the position information of.

The reliability acquisition unit may acquire the reliability information based on the change history of the traveling direction of the user carrying the mobile terminal.

The reliability acquisition unit may acquire reliability information indicating lower reliability as the change angle in the traveling direction and the number of changes in the traveling direction are larger.

Further, in order to solve the above-mentioned problems, according to another viewpoint of the present invention, it is a method executed by a mobile terminal, and the amount of change in the position of the mobile terminal is accumulated in a reference position and calculated. Acquiring the position information of the mobile terminal, acquiring the reliability information of the position information of the mobile terminal based on the elapsed time from the update of the reference position, and the other mobile terminal from the other mobile terminal. The relationship between the acquisition of the position information of the above and the reliability information of the position information of the other mobile terminal, the reliability information of the position information of the mobile terminal, and the reliability information of the position information of the other mobile terminal. Based on the above, controlling the update of the reference position using the position information of the other mobile terminal, and acquiring the reliability information, the set time set at the time of updating the reference position , A method of acquiring the reliability information based on the total of the elapsed time from the update of the reference position is provided.

Further, in order to solve the above problem, according to another viewpoint of the present invention, it is a mobile communication system including a plurality of mobile terminals, and each of the plurality of mobile terminals has a change amount of the position of the mobile terminal. Acquires the reliability information of the position information of the mobile terminal based on the position information acquisition unit that acquires the position information of the mobile terminal calculated by accumulating the above in the reference position and the elapsed time from the update of the reference position. The other terminal information acquisition unit that acquires the position information of the other mobile terminal and the reliability information of the position information of the other mobile terminal from the reliability acquisition unit and the other mobile terminal, and the position information of the mobile terminal. A control unit that controls the update of the reference position using the position information of the other mobile terminal based on the relationship between the reliability information of the other mobile terminal and the reliability information of the position information of the other mobile terminal. The reliability acquisition unit is provided with a mobile communication system that acquires the reliability information based on the sum of the set time set at the time of updating the reference position and the elapsed time from the update of the reference position. ..

As described above, according to the present invention, it is possible to update the position information at an opportunity other than communication with the fixed node.

It is explanatory drawing which shows the structure of the mobile communication system by embodiment of this invention. It is explanatory drawing which shows the structure of the mobile terminal by this embodiment. An example of a beacon configuration is shown. It is explanatory drawing which shows the change with the lapse of time of the probability density function. It is a flowchart which shows the operation of the mobile terminal by embodiment of this invention. It is explanatory drawing which shows the specific example of communication between mobile terminals. It is explanatory drawing which shows the specific example of communication between mobile terminals. It is explanatory drawing which shows the specific example of communication between mobile terminals. It is explanatory drawing which shows typically the relationship between the change angle of a traveling direction and the amount of an error which occurs. It is explanatory drawing which showed the hardware configuration of a mobile terminal.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

Further, in the present specification and the drawings, a plurality of components having substantially the same functional configuration may be distinguished by adding different alphabets after the same reference numerals. For example, a plurality of configurations having substantially the same functional configuration or logical significance are distinguished as necessary, such as mobile terminals 20A, 20B and 20C. However, when it is not necessary to particularly distinguish each of the plurality of components having substantially the same functional configuration, only the same reference numerals are given to each of the plurality of components. For example, when it is not necessary to distinguish the mobile terminals 20A, 20B and 20C, each mobile terminal is simply referred to as a mobile terminal 20.

<1. Configuration of mobile communication system>
FIG. 1 is an explanatory diagram showing a configuration of a mobile communication system according to an embodiment of the present invention. As shown in FIG. 1, the mobile communication system according to the embodiment of the present invention has a plurality of mobile terminals 20A to 20C and a plurality of fixed nodes 30A and 30B.

The fixed node 30 is a node installed at a fixed position, and holds position information indicating its own installation position. The fixed node 30 has a wireless communication function, and periodically transmits a beacon including, for example, its own position information. Such a fixed node 30 may be a public wireless LAN (Local Area Network) access point.

The mobile terminal 20 is an information processing device carried by a user. For example, in the example shown in FIG. 1, the user UA carries the mobile terminal 20A, the user UB carries the mobile terminal 20B, and the user UC carries the mobile terminal 20C. The mobile terminal 20 may be a portable information processing device such as a smartphone, a mobile phone, a PHS (Personal Handyphone System), a portable music playback device, a portable video processing device, a portable game device, and a wearable terminal. ..

Further, the mobile terminal 20 has a wireless communication function for communicating with the fixed node 30 and another mobile terminal 20. The mobile terminal 20 according to the present embodiment has a PDR function of estimating the current position by accumulating the amount of change in the position with respect to the reference position. Since errors are accumulated in the position estimation by the PDR function, when the mobile terminal 20 receives the beacon from the fixed node 30, the mobile terminal 20 updates the reference position using the position information included in the beacon, and the updated reference. Accumulate the amount of change in position with respect to position.

However, the installation of the fixed node 30 is limited in terms of location and cost. If the installation density of the fixed node 30 is insufficient, the method of updating the reference position based only on the beacon from the fixed node 30 will prolong the time interval for updating the reference position and increase the cumulative amount of error. Was a concern.

The present inventor has come to create an embodiment of the present invention with the above circumstances as the first point of view. According to the embodiment of the present invention, the position information can be updated at an opportunity other than communication with the fixed node 30. As a result, it is possible to improve the estimation accuracy of the current position. Hereinafter, the configuration and operation of such an embodiment of the present invention will be sequentially described in detail.

<2. Mobile terminal configuration>
FIG. 2 is an explanatory diagram showing the configuration of the mobile terminal 20 according to the present embodiment. As shown in FIG. 2, the mobile terminal 20 according to the present embodiment includes a sensor unit 220, a change amount calculation unit 230, a reference information management unit 240, a position estimation unit 250, an accuracy identification unit 260, and a transmission unit. It includes 272, a receiving unit 274, a display unit 276, and a battery 278.

(Sensor part)
The sensor unit 220 detects the movement of the mobile terminal 20 and information related to the movement. The sensor unit 220 may include an acceleration sensor 222, an angular velocity sensor 224, and a geomagnetic sensor 226, for example, as shown in FIG. The acceleration sensor 222 acquires information on acceleration, the angular velocity sensor 224 acquires information on angular velocity, and the geomagnetic sensor 226 acquires information on orientation.

(Change calculation unit)
The change amount calculation unit 230 periodically calculates the change amount of the position of the mobile terminal 20 by using the sensor information supplied from the sensor unit 220. Here, the change amount of the position is the change amount of the position of the mobile terminal 20 between the time when the change amount calculation unit 230 calculates the change amount of the position last time and the next calculation of the change amount of the position. Is.

(Standard Information Management Department)
The reference information management unit 240 manages the reference information used for the position estimation by the position estimation unit 250. Specifically, the reference information management unit 240 has a reference information storage unit 242 and an update determination unit 244, as shown in FIG.

The reference information storage unit 242 stores reference position information indicating the reference position and reference accuracy information indicating the reference accuracy as the reference information. The update determination unit 244 is an example of a control unit that determines whether or not to update the reference information and controls the update of the reference information according to the determination result.

For example, when the beacon is received from the fixed node 30 with the received power exceeding the threshold value, the update determination unit 244 updates the reference position information with the position information included in the beacon. Since the distance between the fixed node 30 and the mobile terminal 20 is smaller as the received power is higher, the reliability of the reference position information is improved by updating the reference position information with the position information of the fixed node 30 when the received power exceeds the threshold value. can do. That is, the threshold value of the received power is set when the position shift due to the distance between the mobile terminal 20 and the other mobile terminal 20 is close enough to have no problem in practical use. The update of the reference position information using the position information of the fixed node 30 may be referred to as the first update below.

The reference accuracy information is information indicating the reliability of the reference position information. The update determination unit 244 sets the reference accuracy information to a predetermined value together with the first update.

Further, the update determination unit 244 according to the present embodiment also determines whether or not to update the reference information based on the beacon received from the other mobile terminal 20. The update of the reference information based on the beacon received from the other mobile terminal 20 will be described in detail later.

(Position estimation unit)
The position estimation unit 250 is a position information acquisition unit that accumulates the amount of change in the position of the mobile terminal 20 at a reference position and acquires the position information of the mobile terminal 20. Specifically, the position estimation unit 250 accumulates the change amount of the position calculated by the change amount calculation unit 230 in the reference position information stored in the reference information storage unit 242, so that the current mobile terminal 20 is present. Estimate the position.

(Accuracy identification part)
The accuracy specifying unit 260 is an example of a reliability acquisition unit that specifies the accuracy information (reliability information) of the position information estimated by the position estimation unit 250. As described above, in the position estimation by the PDR function, the error accumulates with the passage of time. Therefore, the accuracy specifying unit 260 may estimate the accuracy information based on the elapsed time from the previous update of the reference position information.

(Transmitter)
The transmission unit 272 transmits a signal to another mobile terminal 20 or a fixed node 30. In particular, the transmission unit 272 according to the present embodiment transmits a beacon including the position information of the mobile terminal 20 estimated by the position estimation unit 250 and the accuracy information specified by the accuracy identification unit 260.

FIG. 3 shows a configuration example of the beacon. As shown in FIG. 3, the beacon consists of a header and a payload. Preamble and control information are stored in the header. The payload includes position information and accuracy information of the mobile terminal 20. The beacon is transmitted at a timing determined according to the communication method.

(Receiver)
The receiving unit 274 receives the signal transmitted from the other mobile terminal 20 or the fixed node 30. For example, the receiving unit 274 includes a fixed node information acquisition unit that receives a beacon including the position information of the fixed node 30 from the fixed node 30, and position information and accuracy information of the other mobile terminal 20 from the other mobile terminal 20. It has a function as another terminal information acquisition unit that receives a beacon.

(Display part)
The display unit 276 displays various information. For example, the display unit 276 may display the position information of the mobile terminal 20 estimated by the position estimation unit 250. The user of the mobile terminal 20 can grasp the current position by visually observing the display unit 276.

(Battery)
The battery 278 is a general-purpose secondary battery. The mobile terminal 20 operates based on the electric power stored in the battery 278.

<3. Accuracy of position estimation ＞
The configuration of the mobile terminal 20 according to the present embodiment has been described above. Subsequently, the accuracy of the position information of the mobile terminal 20 estimated by the position estimation unit 250 will be described.

The actual position of the mobile terminal 20 does not always match the position estimated by the position estimation unit 250. That is, there is a probability that the mobile terminal 20 actually exists at a position (x, y) in the vicinity of the position (x', y') estimated by the position estimation unit 250. The probability that the mobile terminal 20 exists at the position (x, y) is the probability density of the standard bivariate normal distribution shown in the following equation 1 using the position (x', y') estimated by the position estimation unit 250. Expressed as a function. In addition, although the probability density function in the x-coordinate and the y-coordinate is shown in Equation 1, the probability density function in three dimensions in which the height direction is added may be applied.

In Equation 1, σx is the standard deviation of the error in the x coordinate and σy is the standard deviation of the error in the y coordinate. As described above, since the error accumulates with the passage of time in the position estimation by the PDR function, the standard deviations σx and σy are arbitrary functions fx (t) whose values increase with the passage of time from the update of the reference position information. , Fy (t).

For example, the standard deviations σx and σy may be linear functions of time t (elapsed time from the first update) as shown in Equation 2 below, or time as shown in Equation 3 below. It may be a quadratic function of t. In the following formula, a to f are proportional constants. Specific functions can be experimentally designed based on the performance of the sensor.

FIG. 4 is an explanatory diagram showing changes in the probability density function p (x, y) with the passage of time. As mentioned above, since the standard deviations σx and σy increase with the passage of time from the update of the reference position information, the peak of the probability density function p (x, y) decreases with the passage of time, and the probability distribution is overall. Disperse in. This probability density function p (x, y) can be said to be an index indicating the reliability and accuracy of the position information estimated by the position estimation unit 250.

From the above, the accuracy specifying unit 260 specifies the peak value of the probability density function p (x, y) or the probability density function p (x, y) as the accuracy information of the position information estimated by the position estimation unit 250. May be good.

Alternatively, since the peak values of the probability density function p (x, y) and the probability density function p (x, y) depend on the standard deviations σx and σy, the accuracy specifying unit 260 uses the standard deviations σx and σy as accuracy information. May be specified. Further, since the standard deviations σx and σy depend on the elapsed time from the first update, the accuracy specifying unit 260 may specify the elapsed time from the first update as the accuracy information. When the elapsed time from the update of the reference position information is used as the accuracy information, the amount of data for the accuracy information is small, so that the amount of traffic for communication of the accuracy information is suppressed. As described above, the accuracy information specified by the accuracy specifying unit 260 is transmitted from the transmitting unit 272 together with the position information.

<4. Judgment of update of reference position information>
The update determination unit 244 determines whether or not to update the reference position information using the position information included in the beacon received from the other mobile terminal 20 based on the accuracy information included in the beacon. Specifically, when the update determination unit 244 shows higher accuracy than the accuracy information specified by the accuracy specifying unit 260, the accuracy information received from the other mobile terminal 20 is from the other mobile terminal 20. It is determined that the reference position information is updated (overwritten) with the position information included in the received beacon. The update of the reference position information using the position information included in the beacon received from the other mobile terminal 20 may be referred to as a second update below.

For example, when the elapsed time from the first update is used as accuracy information, the update determination unit 244 is specified by the accuracy specifying unit 260 and the elapsed time included in the beacon received from the other mobile terminal 20. Compare with elapsed time. Then, when the elapsed time included in the beacon received from the other mobile terminal 20 is shorter than the elapsed time specified by the accuracy specifying unit 260, the update determination unit 244 is received from the other mobile terminal 20. Update the reference position information with the position information included in the beacon.

Here, the position information received from the other mobile terminal 20 also includes an error. Therefore, when the position estimation unit 250 estimates the position of the mobile terminal 20 using the updated reference position information after the reference position information is updated with the position information received from the other mobile terminal 20, the estimation result Will include the sum of the error included in the reference position information and the error generated after the reference position information is updated.

Therefore, the update determination unit 244 sets the elapsed time included in the beacon received from the other mobile terminal 20 as the reference accuracy information at the time of the second update. After that, the accuracy specifying unit 260 specifies the total time of the elapsed time from the second update and the time (set time) indicated by the reference accuracy information as the accuracy information. Here, the time indicated by the reference accuracy information is the time from the first update performed by the other mobile terminal 20 to the second update performed by the mobile terminal 20. Therefore, the total time corresponds to the elapsed time from the timing when the first update is performed on the other mobile terminal 20 to the present time. By specifying such a total time as accuracy information by the accuracy specifying unit 260, it is possible to reflect both the error included in the reference position information and the error generated after updating the reference position information in the accuracy information. Become. In addition, in this specification, the said total time may be referred to as the elapsed time from the first update for convenience.

As a result, after the mobile terminal 20A updates the reference position information with the position information received from the mobile terminal 20B, the mobile terminal 20C updates the reference position information with the position information received from the mobile terminal 20A. It is possible to appropriately update the reference position information in a chained manner. The update determination unit 244 may update the reference accuracy information to a predetermined value (for example, 0) at the time of the first update.

As a modification, the accuracy information estimated by the position estimation unit 250 and the accuracy information received from the other mobile terminal 20 by the reception unit 274 are the peak value of the probability density function p (x, y) or the standard deviation σx and the standard deviation σx. It may be σy or the like. Even in this case, it is desirable that the elapsed time from the first update is added to the accuracy information. With this configuration, after the update determination unit 244 performs the second update, the accuracy identification unit 260 adds the elapsed time added to the accuracy information received from the other mobile terminal 20 at the time of the second update, and It is possible to specify the standard deviations σx and σy and the peak values of the probability density function p (x, y) based on the total time with the elapsed time from the second update.

<5. Operation>
The configuration of the mobile terminal 20 according to the embodiment of the present invention has been described above. Subsequently, with reference to FIG. 5, the operation of the mobile terminal 20 according to the embodiment of the present invention will be arranged.

FIG. 5 is a flowchart showing the operation of the mobile terminal 20 according to the embodiment of the present invention. As shown in FIG. 5, first, when the reference information storage unit 242 stores the reference information (S304 / Yes), the position estimation unit 250 stores the reference position information stored in the reference information storage unit 242. , The position information of the mobile terminal 20 is estimated by accumulating the change amount of the position calculated by the change amount calculation unit 230 (S308). Further, the accuracy specifying unit 260 specifies the accuracy information of the position information estimated by the position estimating unit 250 (S312). Then, the transmission unit 272 transmits a beacon including the position information of the mobile terminal 20 estimated by the position estimation unit 250 and the accuracy information specified by the accuracy identification unit 260 (S316).

After that, when the beacon is received (S320 / Yes), the update determination unit 244 determines whether or not the reception power of the beacon exceeds the threshold value (S324). When the received power of the beacon is equal to or less than the threshold value (S324 / No), the process from S308 is repeated. On the other hand, when the reception power of the beacon exceeds the threshold value (S324 / Yes), the update determination unit 244 performs different processing depending on whether the source of the beacon is the fixed node 30 or another mobile terminal 20.

Specifically, when the source of the beacon is the fixed node 30 (S328 / fixed node), the update determination unit 244 updates the reference position information of the reference information storage unit 242 with the position information included in the beacon (S332). ), Set a predetermined value in the reference accuracy information (S336).

On the other hand, when the source of the beacon is another mobile terminal 20 (S328 / mobile terminal), the accuracy information received from the other mobile terminal 20 is specified by the accuracy specifying unit 260 in the update determination unit 244. It is determined whether or not the accuracy is higher than the accuracy information (S340). When the accuracy information received from the other mobile terminal 20 shows higher accuracy than the accuracy information specified by the accuracy specifying unit 260 (S340 / Yes), the update determination unit 244 receives from the other mobile terminal 20. The reference position information is updated with the position information included in the beacon (S344). Further, the update determination unit 244 sets the reference accuracy information using the accuracy information included in the beacon received from the other mobile terminal 20 (S348). When the accuracy information received from the other mobile terminal 20 shows lower accuracy than the accuracy information specified by the accuracy specifying unit 260 (S340 / No), the update determination unit 244 determines the reference position information and the reference accuracy information. Do not update. After that, the process from S308 is repeated. Here, if the arrival direction of the radio wave for which the accuracy information is received and the relative distance can be estimated, the position information may be corrected by shifting the received position information to the arrival direction by the relative distance. For example, if an array antenna is used, the arrival direction of radio waves can be estimated from the difference in reception time. As for the relative distance, the relative distance can be estimated based on the received power value by deciding the transmission power in advance and storing the relationship between the distance and the received power strength in the table.

When the reference information storage unit 242 does not store the reference information in S304 (S304 / No), the mobile terminal 20 waits until the beacon is received from the other mobile terminal 20 or the fixed node 30 (S352 /). No). When the beacon is received from the other mobile terminal 20 or the fixed node 30, the processing after S324 is advanced.

Here, the operation of the mobile terminal 20 according to the present embodiment will be described more specifically with reference to FIGS. 6 to 8.

6 to 8 are explanatory views showing a specific example of communication between the mobile terminals 20. 6 to 8 show an example in which the elapsed time (minutes) from the update of the reference position information using the position information of the fixed node 30 is used as the accuracy information.

In the example shown in FIG. 6, at 11:00, the mobile terminal 20A updates the reference position information based on the beacon received from the fixed node 30. Therefore, at 11:00, the accuracy information of the mobile terminal 20A becomes 0 (minutes). It is assumed that the accuracy information of the mobile terminal 20B is 8 (minutes) and the accuracy information of the mobile terminal 20C is 15 (minutes) at 11:00.

After that, as shown in FIG. 7, at 11:05, the mobile terminal 20A and the mobile terminal 20B approach each other, and the mobile terminal 20A and the mobile terminal 20B transmit and receive each other's beacons. At this time, the accuracy information of the mobile terminal 20A is 5 (minutes), the accuracy information of the mobile terminal 20B is 13 (minutes), and the accuracy information of the mobile terminal 20A is higher than the accuracy information of the mobile terminal 20B. Therefore, the mobile terminal 20B updates the reference position information by using the position information included in the beacon received from the mobile terminal 20A. Further, the mobile terminal 20B sets 5 (minutes), which is the accuracy information of the mobile terminal 20A, as the reference accuracy information.

Further, as shown in FIG. 8, at 11:10, the mobile terminal 20B and the mobile terminal 20C approach each other, and the mobile terminal 20B and the mobile terminal 20C transmit and receive each other's beacons. At this time, the accuracy information of the mobile terminal 20B is 10 (minutes), the accuracy information of the mobile terminal 20C is 25 (minutes), and the accuracy information of the mobile terminal 20B is higher than the accuracy information of the mobile terminal 20C. Therefore, the mobile terminal 20C updates the reference position information using the position information included in the beacon received from the mobile terminal 20B. Further, the mobile terminal 20C sets 10 (minutes), which is the accuracy information of the mobile terminal 20B, as the reference accuracy information.

In this way, each mobile terminal 20 can update the reference position information using more probable position information received from the other mobile terminal 20. Therefore, according to the present embodiment, since the opportunity for updating the reference position information increases, it is possible to improve the accuracy of position estimation by the mobile terminal 20.

<6. Application example>
The embodiments of the present invention have been described above. Various applications can be applied to the above-described embodiments of the present invention. Hereinafter, an example of application applicable to the embodiment of the present invention will be described.

The position estimation unit 250 can calculate the traveling distance of the user based on the information obtained from the acceleration sensor 222, and can calculate the traveling direction of the user based on the information obtained from the angular velocity sensor 224. It is experimentally known that the error of the traveling distance and the error of the traveling direction can be approximated by a normal distribution.

The position estimation unit 250 can estimate the position (x', y') of the mobile terminal 20 according to the following mathematical formula by using the traveling distance D and the traveling direction E.

According to the equation 4, the accuracy of the position estimation by the position estimation unit 250 depends on the accuracy of the traveling distance D and the traveling direction E. Here, the degree of decrease in accuracy of the traveling distance D and the traveling direction E also differs depending on the movement history of the user. For example, the larger the change in the angular velocity, the more likely it is that an error will be added to the information regarding the angular velocity detected by the angular velocity sensor 224.

FIG. 9 is an explanatory diagram schematically showing the relationship between the change angle in the traveling direction and the amount of error that occurs. As shown in FIG. 9, as the absolute value of the change angle in the traveling direction increases, the amount of error that occurs increases, for example, in a quadratic function. Therefore, when the user changes the traveling direction, an error is likely to be added as compared with the case where the user is walking straight. The same applies to the moving speed, and it is considered that the faster the moving speed, the easier it is for an error to be added.

Therefore, the accuracy specifying unit 260 according to the application example specifies the accuracy information based on the elapsed time from the first update and the movement history such as the change history of the user's traveling direction and the moving speed. For example, the accuracy specifying unit 260 may specify the standard deviation expressed by a mathematical expression in which a term calculated based on the user's movement history is added to the right side of the mathematical expression 2 or 3 as accuracy information.

It is desirable that the above term is a term showing a larger value as the change angle in the traveling direction and the number of changes in the traveling direction increase. For example, the above term may be a multiplication of the number of times the change angle of the user's traveling direction exceeds the threshold value and a predetermined count. In a building, the corner is often 90 degrees, so from the viewpoint of using the number of times the user has turned the corner, the threshold value may be 90 degrees, or the user may gently turn the corner. In consideration of this, the threshold value may be set to less than 90 degrees, for example, 80 degrees. Alternatively, the above term may indicate a cumulative value of weights according to a change angle in the traveling direction.

According to such an application example, since the accuracy specifying unit 260 can more appropriately specify the accuracy information, the update determination unit 244 can also make a more appropriate determination regarding the update of the reference position information. Become. Similarly, as for the moving distance, an error can be added as the moving distance per unit time increases. Therefore, the accuracy specifying unit 260 may specify the accuracy information based on the history of the moving distance.

<7. Hardware configuration>
The embodiments of the present invention have been described above. Information processing such as the position estimation and update determination described above is realized by the cooperation between the software and the hardware of the mobile terminal 20 described below.

FIG. 10 is an explanatory diagram showing the hardware configuration of the mobile terminal 20. As shown in FIG. 10, the mobile terminal 20 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, an input device 208, an output device 210, and the like. It includes a storage device 211 and a communication device 215.

The CPU 201 functions as an arithmetic processing unit and a control device, and controls the overall operation in the mobile terminal 20 according to various programs. Further, the CPU 201 may be a microprocessor. The ROM 202 stores programs, calculation parameters, and the like used by the CPU 201. The RAM 203 temporarily stores a program used in the execution of the CPU 201, parameters that change appropriately in the execution, and the like. These are connected to each other by a host bus composed of a CPU bus or the like. By the collaboration between the CPU 201, ROM 202 and RAM 203 and the software, functions such as a change amount calculation unit 230, a reference information management unit 240, a position estimation unit 250, and an accuracy identification unit can be realized.

The input device 208 includes input means for the user to input information such as a mouse, keyboard, touch panel, buttons, microphone, switch, and lever, and an input control circuit that generates an input signal based on the input by the user and outputs the input signal to the CPU 201. It is composed of such as. By operating the input device 208, the user of the mobile terminal 20 can input various data to the mobile terminal 20 and instruct the processing operation.

The output device 210 includes, for example, a liquid crystal display (LCD) device, an OLED (Organic Light Emitting Device) device, and a display device such as a lamp. Further, the output device 210 includes an audio output device such as a speaker and headphones. For example, the display device displays an captured image, a generated image, or the like. On the other hand, the voice output device converts voice data and the like into voice and outputs the data.

The storage device 211 is a data storage device configured as an example of the storage unit of the mobile terminal 20 according to the present embodiment. The storage device 211 may include a storage medium, a recording device that records data on the storage medium, a reading device that reads data from the storage medium, a deleting device that deletes the data recorded on the storage medium, and the like. The storage device 211 stores a program executed by the CPU 201 and various data.

The communication device 215 is a communication interface composed of a communication device or the like for communicating with another device. The communication device 215 may be a wireless LAN (Local Area Network) compatible communication device, an LTE (Long Term Evolution) compatible communication device, or a wire communication device that performs wired communication.

<8. Conclusion>
As described above, the mobile terminal 20 according to the embodiment of the present invention can update the reference position information by using the more probable position information received from the other mobile terminal 20. Therefore, according to the present embodiment, since the opportunity for updating the reference position information increases, it is possible to improve the accuracy of position estimation by the mobile terminal 20.

Although preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

For example, in the above embodiment, the mobile terminal 20 has a position estimation function, but the mobile terminal 20 does not have to have a position estimation function. In this case, the mobile terminal 20 transmits the information obtained by the sensor unit 220 to the fixed node 30, the fixed node 30 estimates the position information of the mobile terminal 20 based on the information received from the mobile terminal 20, and the fixed node 30 May notify the mobile terminal 20 of the position information by, for example, a beacon.

Further, the fixed node 30 may have a beacon transmitting unit for transmitting a beacon, a receiving unit for receiving the position information of the mobile terminal 20 from the mobile terminal 20, and a display unit for displaying the position information of the mobile terminal 20. Good.

Further, when each mobile terminal 20 transmits a probability density function as accuracy information, each mobile terminal 20 is subjected to statistical processing using the probability density function received from a plurality of other mobile terminals 20 to perform statistical processing of the mobile terminal 20. It is also possible to estimate the position. For example, maximum likelihood estimation can be mentioned as statistical processing, and according to maximum likelihood estimation, the current position of the mobile terminal 20 can be estimated from a plurality of probability density functions.

Further, although the fixed node 30 has been described above as an example of the device that provides accurate position information, the device that provides accurate position information is not limited to the fixed node 30. For example, a device having a GPS function, a device having a function of estimating its own position based on the reception intensity of radio waves received from a plurality of devices whose positions are known, and the like are devices that provide accurate position information. It is also possible to apply to the embodiment of the present invention.

Further, each step in the processing of the mobile terminal 20 of the present specification does not necessarily have to be processed in chronological order in the order described as a sequence diagram or a flowchart. For example, each step in the processing of the mobile terminal 20 may be processed in an order different from the order described in the flowchart, or may be processed in parallel.

Further, it is possible to create a computer program for causing the hardware such as the CPU 201, ROM 202, and RAM 203 built in the mobile terminal 20 to exhibit the same functions as each configuration of the mobile terminal 20 described above. A storage medium for storing the computer program is also provided.

20 Mobile terminal 30 Fixed node 220 Sensor unit 222 Accelerometer 224 Angular velocity sensor 226 Geomagnetic sensor 230 Change amount calculation unit 240 Reference information management unit 242 Reference information storage unit 244 Update judgment unit 250 Position estimation unit 260 Accuracy identification unit 272 Transmission unit 274 Reception Unit 276 Display unit 278 Battery

Claims (9)

It ’s a mobile terminal,
A position information acquisition unit that acquires the position information of the mobile terminal calculated by accumulating the amount of change in the position of the mobile terminal at the reference position.
A reliability acquisition unit that acquires reliability information of the position information of the mobile terminal based on the elapsed time from the update of the reference position, and
Another terminal information acquisition unit that acquires the position information of the other mobile terminal and the reliability information of the position information of the other mobile terminal from the other mobile terminal.
Control to control the update of the reference position using the position information of the other mobile terminal based on the relationship between the reliability information of the position information of the mobile terminal and the reliability information of the position information of the other mobile terminal. Department and
With
The reliability acquisition unit is a mobile terminal that acquires the reliability information based on the total of the set time set at the time of updating the reference position and the elapsed time from the update of the reference position . The mobile terminal according to claim 1 , wherein the control unit sets the set time using the reliability information of the position information of the other mobile terminal in addition to updating the reference position. The mobile terminal
A fixed node information acquisition unit that acquires the position information of the fixed node from the fixed node is further provided.
The mobile terminal according to claim 2, wherein the control unit updates the reference position using the position information of the fixed node and sets the set time to a predetermined value. The control unit determines whether or not the reception strength of the signal received from the other mobile terminal exceeds the threshold value, and based on the reception strength of the signal received from the other mobile terminal exceeds the threshold value. The mobile terminal according to any one of claims 1 to 3 , which controls updating of the reference position using the position information of the other mobile terminal. The control unit is based on the fact that the reliability indicated by the reliability information of the position information of the other mobile terminal is higher than the reliability indicated by the reliability information of the position information of the mobile terminal. The mobile terminal according to any one of claims 1 to 4 , which controls the update of the reference position using the position information of the above. The mobile terminal according to any one of claims 1 to 5 , wherein the reliability acquisition unit acquires the reliability information based on a change history of the traveling direction of a user carrying the mobile terminal. The mobile terminal according to claim 6 , wherein the reliability acquisition unit acquires reliability information indicating lower reliability as the change angle in the traveling direction and the number of changes in the traveling direction are larger. A method performed by a mobile terminal,
Acquiring the position information of the mobile terminal calculated by accumulating the amount of change in the position of the mobile terminal at the reference position, and
Acquiring reliability information of the position information of the mobile terminal based on the elapsed time from the update of the reference position, and
Acquiring the position information of the other mobile terminal and the reliability information of the position information of the other mobile terminal from the other mobile terminal,
Controlling the update of the reference position using the position information of the other mobile terminal based on the relationship between the reliability information of the position information of the mobile terminal and the reliability information of the position information of the other mobile terminal. When,
Including
A method of acquiring the reliability information based on the sum of the set time set at the time of updating the reference position and the elapsed time from the update of the reference position . A mobile communication system consisting of multiple mobile terminals
Each of the plurality of mobile terminals
A position information acquisition unit that acquires the position information of the mobile terminal calculated by accumulating the amount of change in the position of the mobile terminal at the reference position.
A reliability acquisition unit that acquires reliability information of the position information of the mobile terminal based on the elapsed time from the update of the reference position, and
Another terminal information acquisition unit that acquires the position information of the other mobile terminal and the reliability information of the position information of the other mobile terminal from the other mobile terminal.
Control to control the update of the reference position using the position information of the other mobile terminal based on the relationship between the reliability information of the position information of the mobile terminal and the reliability information of the position information of the other mobile terminal. Department and
With
The reliability acquisition unit is a mobile communication system that acquires the reliability information based on the total of the set time set at the time of updating the reference position and the elapsed time from the update of the reference position .

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