JP2011112424A - Portable navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable navigation system utilized at a location at which GPS radio waves are less likely to be received, and improving the accuracy in position detection. <P>SOLUTION: At least three magnetic field generating sources 4a-4c for generating AC magnetic fields having mutually different frequencies are disposed at predetermined positions. The AC magnetic fields are detected, by using a triaxial magnetic sensor 3a mounted to a portable terminal 2 and are resolved at each frequency. The strength of the AC magnetic field is calculated at each frequency. Distances from the portable terminal 2 to the magnetic field generating sources are calculated from the strength values. A position of the portable terminal 2 is identified. A travel start position of a user 6 can be correctly identified, even at a location at which the GPS radio waves are less likely to be received. When the user 6 moves, the current position of the user 6 is identified by an autonomous navigation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a portable navigation system that detects a current position of a user.

  2. Description of the Related Art Conventionally, a portable navigation system that detects a user's current position using GPS radio waves is known (see Patent Document 1 below). This portable navigation system includes a GPS radio wave reception unit in a mobile terminal, calculates the current position of the mobile terminal using the GPS radio wave received by the reception unit, and displays map information of the position on the display screen.

  A portable navigation system that can be used even in places where GPS radio waves are difficult to reach is also known (see Patent Document 2 below). This portable navigation system identifies this base station by communicating with a plurality of base stations existing around the portable terminal, for example. And the present position of a portable terminal is specified using the position information of the base station memorized beforehand.

JP 2007-024700 A Japanese Patent Laid-Open No. 2004-219076

  However, the portable navigation system using the position of the base station has a problem that the accuracy is poor compared to the case where GPS radio waves are used. Therefore, a portable navigation system that can be used in places where GPS radio waves are difficult to reach and has high position detection accuracy is desired.

  The present invention is intended to provide a portable navigation system that can be used in places where GPS radio waves are difficult to reach and has high position detection accuracy.

The present invention is a portable navigation system for detecting the current position of a user holding a portable terminal,
At least three magnetic field generation sources that generate alternating magnetic fields having different frequencies are arranged at predetermined positions,
The mobile device
A triaxial magnetic sensor for detecting magnetic fields in three directions orthogonal to each other;
A triaxial acceleration sensor that detects acceleration in three directions orthogonal to each other;
Based on the alternating magnetic field detected by the three-axis magnetic sensor, a progress start position specifying means for specifying a user's progress start position;
Based on the geomagnetism detected by the triaxial magnetic sensor and the gravitational acceleration detected by the triaxial acceleration sensor, a traveling direction identifying means for identifying the traveling direction of the user,
A current position specifying means for specifying the current position of the user when the user moves from the progress start position;
The advancing start position specifying means includes a storage means for storing an arrangement position of the magnetic field generation source and a magnet strength of the magnetic field generation source, and a detection signal of the alternating magnetic field detected by the three-axis magnetic sensor for each frequency. And a frequency separation means for separating the signal into the magnetic field, and calculating the distance from the three-axis magnetic sensor to each of the magnetic field generation sources based on the strength of the alternating magnetic field for each frequency. Identify the starting position,
The current position specifying means detects the user's walking step by step based on a change in acceleration detected by the three-axis acceleration sensor, and the user's stepwise moving direction detected by the moving direction specifying means; Based on the user's stride stored in advance, the user's walking vector for each step is obtained, and all the walking vectors from the progress start position to the current position are added on the map information, thereby the user The present position is specified in a portable navigation system (claim 1).

The effect of the present invention will be described. The portable navigation system of the present invention is provided with at least three magnetic field generation sources that generate alternating magnetic fields having different frequencies from each other at predetermined locations. Then, the AC magnetic field transmitted from the magnetic field generation source is received by the three-axis magnetic sensor, and the user's progress start position is specified. When the user moves to a place where the AC magnetic field does not reach after specifying the progress start position, the current position specifying means specifies the current position of the user using so-called autonomous navigation.
In this way, the user's position can be accurately identified even in a place where GPS radio waves are difficult to reach. That is, the three magnetic field generation sources are set in advance in a place where GPS radio waves are difficult to reach, such as an underground shopping mall or a shopping mall, and an alternating magnetic field transmitted from the three magnetic field generation sources is detected by a three-axis magnetic sensor. If received, the user's position can be accurately identified without using GPS radio waves.

  In order to specify the position of the user using an alternating magnetic field, the following method is used. That is, since the magnetic field detected by the triaxial magnetic sensor is obtained by superimposing three alternating magnetic fields, the alternating magnetic field detected by the triaxial magnetic sensor is first separated for each frequency. Then, the strength of the alternating magnetic field for each frequency is calculated. Since the strength of the magnet included in the magnetic field generation source is stored in advance, the distances from the three-axis magnetic sensor to the three magnetic field generation sources can be obtained based on the detected strength of the alternating magnetic field. Further, since the position of the magnetic field generation source is also stored, the position of the user holding the portable terminal can be specified from the position information of each magnetic field generation source and the distance to the magnetic field generation source. This makes it possible to accurately obtain the user's progress start position without using GPS radio waves.

  After the user's travel start position is specified using the AC magnetic field, when the user moves to a place where the AC magnetic field does not reach, as described above, the user's current position is determined using the so-called autonomous navigation by the current position specifying means. Is identified. That is, the user's walking is detected step by step from the change in acceleration detected by the three-axis acceleration sensor. Further, the traveling direction of the user holding the mobile terminal is detected step by step from the gravitational acceleration detected by the triaxial acceleration sensor and the geomagnetism intensity detected by the triaxial magnetic sensor. Then, a walking vector for each step of the user is obtained from the step length of the user stored in advance and the traveling direction of the user for each step. This walking vector is a vector in which the traveling direction of the user detected by the traveling direction specifying means during one step is the direction and the stride is the magnitude. On the map information, the current position of the user can be specified by adding all the walking vectors from the progress start position to the current position.

  As described above, according to the present invention, since the user's progress start position can be accurately specified, the current position of the user by autonomous navigation, which is performed thereafter, can also be accurately determined.

  As described above, according to the present invention, it is possible to provide a portable navigation system that can be used even in places where GPS radio waves are difficult to reach and has high position detection accuracy.

1 is a conceptual diagram of a portable navigation system in Embodiment 1. FIG. 1 is a conceptual diagram of a mobile terminal in Embodiment 1. FIG. 1 is a block diagram of a mobile terminal in Embodiment 1. FIG. The detection signal of the alternating magnetic field which the 3-axis magnetic sensor in Example 1 detected, and this detection signal isolate | separated for every frequency. 3 is a graph showing a relationship between a distance from a magnetic field generation source and a magnetic field in Example 1. 1 is a partially cutaway perspective view of a mobile terminal in Embodiment 1. FIG. Explanatory drawing of the method of specifying the advancing direction of a user in Example 1. FIG. Explanatory drawing of the place where a portable navigation system is used in Example 1. FIG. 1 is a flowchart of a portable navigation system in Embodiment 1. The flowchart following FIG.

A preferred embodiment of the present invention described above will be described.
In the present invention, the magnetic field generating source is arranged in an entrance hall provided near the entrance of the building, and a continuous passage extends from the entrance hall to the position where the AC magnetic field does not reach in the building. The advancing start position specifying means specifies the advancing start position of the user when the user enters the entrance hall, and the current position specifying means is configured to specify the user's advancing start position when the user enters the aisle. It is preferable that the current position is specified (claim 2).
If it does in this way, since the GPS electric wave cannot reach easily in a building, the effect of the present invention can fully be acquired. Here, the building refers to, for example, a shopping mall, a multistory parking lot, an airport, an underground mall, and the like. When a user enters these buildings, GPS radio waves cannot be detected. However, if a magnetic field generation source is provided in the entrance hall, an AC magnetic field transmitted from the magnetic field generation source is detected, and the user's progress The starting position can be accurately identified. In addition, when the user enters the above passage, even if the AC magnetic field can no longer be detected, the advance start position is accurately specified. Therefore, the current position of the user must be accurately specified by autonomous navigation. Can do.

The frequency of the alternating magnetic field is preferably 1 to 40 Hz or 70 to 500 Hz.
If it does in this way, the frequency band of 50-60 Hz used as a commercial frequency can be avoided, and it will become difficult for noise to enter a triaxial magnetic sensor. Further, when an alternating magnetic field is generated by rotating a magnet, it may be difficult to generate an alternating magnetic field of 500 Hz or more. The frequency of the alternating magnetic field is more preferably in the range of 8 to 13 Hz.

The frequency separation means preferably separates the alternating magnetic field for each frequency by Fourier transform.
In this way, the alternating magnetic field can be accurately separated for each frequency. Therefore, it becomes easy to calculate the distance from the mobile terminal to each magnetic field generation source. Thereby, it becomes easy to accurately specify the progress start position of the user holding the mobile terminal.

The triaxial magnetic sensor is preferably a magnetic impedance sensor formed by winding a coil around an amorphous wire.
Since the magnetic impedance sensor can detect a minute magnetic field, it is possible to detect an alternating magnetic field even at a position away from the magnetic field generation source. Therefore, the range which can specify a user's progress start position can be expanded.

Example 1
A portable navigation system according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the mobile navigation system 1 of this example detects the current position of the user 6 holding the mobile terminal 2. In the portable navigation system 1, at least three magnetic field generation sources 4a to 4c that generate alternating magnetic fields having different frequencies are arranged at predetermined positions.
As shown in FIG. 6, the mobile terminal 2 includes a triaxial magnetic sensor 3a that detects magnetic fields M (Mx, My, Mz) in three directions X, Y, and Z orthogonal to each other. The mobile terminal 2 includes a triaxial acceleration sensor 3b that detects acceleration G (Gx, Gy, Gz) in three directions X, Y, and Z orthogonal to each other.
Here, X is a direction facing the horizontal direction of the operation unit 15 of the mobile terminal 2, and Y is a direction facing the vertical direction of the operation unit 15 of the mobile terminal 2. Z is a direction facing the thickness direction of the operation unit 15 of the mobile terminal 2.

  As shown in FIG. 2, the mobile terminal 2 includes a travel start position identifying unit 5 that identifies the travel start position of the user 6 based on the alternating magnetic field detected by the three-axis magnetic sensor 3a. Further, the mobile terminal 2 includes a traveling direction identifying means 7 that identifies the traveling direction of the user 6 based on the geomagnetism detected by the triaxial magnetic sensor 3a and the gravitational acceleration detected by the triaxial acceleration sensor 3b. And the portable terminal 2 is provided with the present position specific | specification means 8 which pinpoints the present position of the user 6 when the user 6 moves from a progress start position.

  As shown in FIG. 2, the advancing start position specifying means 5 includes a storage means 22 for storing the arrangement position of the magnetic field generation source 4 and the strength of the magnet of the magnetic field generation source 4, and an alternating magnetic field detected by the triaxial magnetic sensor 3a Frequency separation means 26 for separating the detection signals for each frequency, and based on the alternating magnetic field strength for each frequency, distances ra to rc from the three-axis magnetic sensor 3a to the magnetic field generation sources 4a to 4c (see FIG. 1) is specified, the progress start position of the user 6 having the portable terminal 2 is specified.

Further, as shown in FIG. 8, the current position specifying unit 8 detects the walking of the user 6 step by step based on the change in acceleration detected by the triaxial acceleration sensor 3 b, and the user 6 detected by the traveling direction specifying unit 7. The walking vector V of the user 6 for each step is obtained based on the traveling direction for each step and the user's stride stored in advance, and all walking vectors V from the starting position to the current position on the map information are obtained. By adding together, the current position of the user 6 is specified.
The details will be described below.

  As shown in FIG. 1, the magnetic field generation source 4 has a central portion of a rod-shaped magnet 40 attached to a rotating shaft of a motor 41, and generates an alternating magnetic field by rotating the magnet 40 with the motor 41. As illustrated, a first magnetic field generation source 4a, a second magnetic field generation source 4b, and a third magnetic field generation source 4c are attached to positions A, B, and C, which are different horizontal positions, respectively. These magnetic field generation sources 4a to 4c have different rotational speeds of the motor 41, and thereby generate alternating magnetic fields having different frequencies. The rotation shafts of the motors 41 of the magnetic field generation sources 4a to 4c are each directed in the horizontal direction. The frequency of the alternating magnetic field is 1 to 40 Hz or 70 to 500 Hz. The mounting heights of the magnetic field generation sources 4a to 4c are all the same. The magnetic field generation sources 4a to 4c are preferably attached to a height at which the user 6 holds the portable terminal 2, for example, a height position of 90 to 110 cm.

Next, a method for specifying the user's progress start position by the progress start position specifying means 5 will be described.
As described above, the triaxial magnetic sensor 3a (see FIG. 6) mounted on the mobile terminal 2 detects the magnetic field M (Mx, My, Mz) in the X, Y, and Z directions orthogonal to each other. The triaxial magnetic sensor 3b detects accelerations G (Gx, Gy, Gz) in the X, Y, and Z directions orthogonal to each other.
The magnetic field detected by the three-axis magnetic sensor 3a is obtained by overlapping alternating magnetic fields transmitted from the three magnetic field generation sources 4a to 4b. Therefore, the magnetic field M detected by the three-axis magnetic sensor 3a is separated for each frequency. That is, as shown in FIG. 4, the component Mx in the X direction of the magnetic field M is _divided into a magnetic field _Max generated from the first magnetic field generation source 4a, a magnetic field M _bx generated from the second magnetic field generation source 4b, and a third magnetic field generation. Separated into a magnetic field _Mcx generated from the source 4c. Similarly, the Y-direction component My of the magnetic field M, a magnetic field M _ay generated from the first magnetic field source 4a, a magnetic field M _By generated by the second magnetic field generating source 4b, generated from the third magnetic field generating source 4c Separated into a magnetic field _Mcy . Further, the component Mz in the Z direction of the magnetic field M is _divided into a magnetic field M _az generated from the first magnetic field generation source 4a, a magnetic field M _bz generated from the second magnetic field generation source 4b, and a magnetic field generated from the third magnetic field generation source 4c. Separated into M _cz .

  Based on the following formula, the intensity | Ma | of the magnetic field Ma generated from the first magnetic field generation source 4a, the intensity | Mb | of the magnetic field Mb generated from the second magnetic field generation source 4b, and the third magnetic field generation source The intensity | Mc | of the magnetic field Mc generated from 4c is calculated.

FIG. 5 shows the relationship between the distance from the magnetic field generation source 4 and the strength of the magnetic field to be detected. The portable terminal 2 stores this relationship and the strength of the magnet 40 of each magnetic field generation source 4. From this relationship and the intensity | Ma | of the magnetic field Ma generated from the first magnetic field generation source 4a, the distance ra from the first magnetic field generation source 4a to the portable terminal 2 is calculated as shown in FIG. Similarly, a distance rb from the second magnetic field generation source 4b to the portable terminal 2 and a distance rc from the third magnetic field generation source 4c to the portable terminal are calculated.
Moreover, the portable terminal has memorize | stored the arrangement position of the magnetic field generation sources 4a-4c. Using this arrangement position and the distances ra to rc, the progress start position of the user 6 is specified.

Next, a method for specifying the traveling direction of the user 6 will be described. As shown in FIGS. 6 and 7, the three-axis magnetic sensor 3 a and the three-axis acceleration sensor 3 b are used to calculate the direction of the east, west, north, and south directions of the Y axis of these sensors 3. Since the user 6 often moves with the Y axis of the mobile terminal 2 facing the front, the direction of the Y axis can be regarded as the traveling direction of the user.
As shown in FIG. 7, the axis Y ′ is the Y axis projected onto the horizontal plane H, and the axis 500 is the axis 500 heading toward the magnetic north N through the point O ′ projected on the horizontal plane with the origin O of the X, Y, and Z axes. The angle θ can be calculated from the geomagnetism M (Mx, My, Mz) and the gravitational acceleration G (Gx, Gy, Gz) by the following equation. Thereby, it becomes possible to specify the traveling direction of the user 6. The geomagnetism M (Mx, My, Mz) can be measured even in an underground city where GPS radio waves do not reach.

Next, a method for detecting the current position of the user 6 when the user 6 moves to an area where the AC magnetic field cannot be detected will be described. Since the acceleration detected by the three-axis acceleration sensor 3b changes when the user 6 walks, the walking of the user 6 can be detected step by step by the change in acceleration. Further, as described above, the traveling direction identifying means 7 can identify the traveling direction of the user 6 step by step. Then, as shown in FIG. 8, a walking vector V for each step of the user 6 is calculated from the step length of the user 6 stored in advance and the traveling direction of the user 6 for each step. The walking vector V is a vector in which the traveling direction of the user 7 detected by the traveling direction specifying means 7 during the one step is the direction, and the stride is the magnitude.
When the user 6 moves from the travel start position SP to the path 101 where the AC magnetic field cannot be detected, all the walking vectors V of the user 6 from the travel start position SP to the current position CP are added on the map information. This makes it possible to accurately specify the current position CP of the user even in the place 101 where the AC magnetic field and the GPS radio wave do not reach.

  In the portable navigation system 1 of this example, as shown in FIG. 8, the magnetic field generation sources 4 a to 4 c are arranged in the entrance hall EH provided near the entrance / exit of the building 100. A continuous passage 101 extends from the entrance hall EH into the building 100 to a position where the AC magnetic field does not reach. The advancing start position specifying means 5 specifies the advancing start position SP of the user 6 when the user 6 enters the entrance hall EH, and the current position specifying means 8 is the user 6 when the user 6 enters the passage 101. The current position CP is specified.

Next, the configuration of the mobile terminal will be described. As shown in FIG. 3, the mobile terminal 2 includes a microcomputer 20. The microcomputer 20 includes a triaxial magnetic sensor 3 a, a triaxial acceleration sensor 3 b, a display unit 14, an operation unit 15, a microphone 16, a communication control unit 11, and a rear speaker 12. The vibrator 13, the transmission / reception unit 111, the GPS antenna 51, and the GPS positioning unit 52 are connected. As the three-axis magnetic sensor 3a, a magnetic impedance sensor formed by winding a coil around an amorphous wire is used.
The microcomputer 20 includes a CPU 21, ROM 22, RAM 23, I / O 24, and connection line 25. The ROM 22 stores a program 22p and data 22d such as position information and map information of the magnetic field generation source 4. When the CPU 21 reads and executes the program 22p, the travel start position specifying means 5, the travel direction specifying means 7, the current position specifying means 8 and the frequency separating means 26 of this example are realized.

The flowchart of the program 22p is shown in FIGS. When the program 22p is started and the user enters the entrance hall EH (see FIG. 8), the three-axis magnetic sensor 3a detects the AC magnetic field transmitted from the magnetic field generation sources 4a to 4c (step S1).
Thereafter, the AC magnetic field is separated for each frequency by the frequency separation means 26 (step S2). At this time, Fourier transform can be used. A band filter that allows only a certain frequency to pass may be used.

  Thereafter, the strength of the magnetic field is calculated for each frequency (step S3), and the distances ra to rc from the portable terminal 2 to the magnetic field generation sources 4a to 4c are calculated (step S4). Then, the progress start position of the user 6 is specified and displayed on the display screen 14 (step S5).

  When the user 6 moves to an area where the AC magnetic field does not reach, the walking of the user 6 is detected step by step by the triaxial acceleration sensor 3b (step S6), and the traveling direction of the user 7 is detected step by step by the traveling direction specifying means 7. Detect (step S7). Then, the walking vector V for each step of the user 6 is calculated, and the walking vector V is added from the progress start position SP on the map information (see FIG. 8) (step S8). Thus, the current position CP of the user 6 is specified and displayed on the display screen 14 (step S9).

  Every time the user 6 advances one step, steps S6 to S9 are processed (step S10). If the user 6 has finished the program 22p, the process ends (step S10).

  Next, the function and effect of this example will be described. In the portable navigation system 1 of the present example, at least three magnetic field generation sources 4a to 4c that generate alternating magnetic fields having different frequencies are provided at predetermined locations. Then, the AC magnetic field transmitted from the magnetic field generation sources 4a to 4c is received by the three-axis magnetic sensor 3a, and the travel start position SP of the user 6 is specified. After the advance start position SP is specified, when the user 6 moves to a place where the AC magnetic field does not reach, the current position specifying unit 8 specifies the current position CP of the user 6 using so-called autonomous navigation.

  In this way, the position of the user 6 can be accurately specified even in a place where GPS radio waves are difficult to reach. That is, the three magnetic field generation sources 4a to 4c are installed in advance in a place where GPS radio waves are difficult to reach, such as an underground shopping mall or a shopping mall, and the alternating magnetic fields transmitted from the three magnetic field generation sources 4a to 4c are Since it is received by the three-axis magnetic sensor 3a, it is possible to accurately specify the travel start position SP of the user 6 without using GPS radio waves.

  In this example, since the progress start position SP can be accurately specified, it is possible to accurately specify the current position of the user 6 using autonomous navigation performed thereafter.

In this example, as shown in FIG. 8, magnetic field generation sources 4 a to 4 c are arranged in the entrance hall EH provided near the entrance of the building 100, and an AC magnetic field reaches the building 100 from the entrance hall EH. A continuous passage 101 extends to a position where there is not. Then, when the user 6 enters the entrance hall EH, the travel start position SP of the user 6 is specified, and when the user 6 enters the passage 101, the current position CP of the user 6 is specified.
If it does in this way, since the GPS radio wave does not easily reach in the building 100, the effect of this example can be sufficiently obtained. Here, the building 100 is, for example, a shopping mall, a multi-storey parking lot, an airport, an underground mall, or the like. When the user 6 enters these buildings 100, GPS radio waves cannot be detected. However, if the magnetic field generation sources 4a to 4c are provided in the entrance hall EH, the AC magnetic field transmitted from the magnetic field generation sources 4a to 4c. Can be detected, and the user 6's progress start position SP can be accurately identified. In addition, when the user 6 enters the passage 101, even if the AC magnetic field cannot be detected, the travel start position SP is accurately specified. Therefore, the current position of the user 6 is accurately determined by autonomous navigation. Can be identified.

In this example, the frequency of the alternating magnetic field is 1 to 40 Hz or 70 to 500 Hz.
If it does in this way, the frequency band of 50-60 Hz used as a commercial frequency can be avoided, and it becomes difficult for noise to enter the triaxial magnetic sensor 3a. In addition, when an alternating magnetic field is generated by rotating the magnet 40, it may be difficult to generate an alternating magnetic field of 500 Hz or more. The frequency of the alternating magnetic field is more preferably in the range of 8 to 13 Hz.

In this example, the frequency separation means 26 separates the alternating magnetic field for each frequency by Fourier transform.
In this way, the alternating magnetic field can be accurately separated for each frequency. Therefore, it becomes easy to calculate the distances ra to rc from the mobile terminal 2 to the magnetic field generation sources 4a to 4c. Thereby, it becomes easy to pinpoint the advance start position SP of the user 6 holding the portable terminal 2 accurately.

In this example, the triaxial magnetic sensor 3a is a magnetic impedance sensor formed by winding a coil around an amorphous wire.
Since the magnetic impedance sensor can detect a minute magnetic field, it is possible to detect an alternating magnetic field even at a position away from the magnetic field generation source 4. Therefore, the range in which the user 6 can determine the progress start position SP can be expanded.

  As described above, according to this example, it is possible to provide a portable navigation system that can be used even in places where GPS radio waves are difficult to reach and has high position detection accuracy.

DESCRIPTION OF SYMBOLS 1 Portable navigation system 2 Portable terminal 22 Memory | storage means 26 Frequency separation means 3a 3 axis | shaft magnetic sensor 3b 3 axis | shaft acceleration sensor 4 Magnetic field generation source 5 Progress start position specific means 6 User 7 Travel direction specific means 8 Current position specific means

Claims (5)

A mobile navigation system for detecting a current position of a user holding a mobile terminal,
At least three magnetic field generation sources that generate alternating magnetic fields having different frequencies are arranged at predetermined positions,
The mobile device
A triaxial magnetic sensor for detecting magnetic fields in three directions orthogonal to each other;
A triaxial acceleration sensor that detects acceleration in three directions orthogonal to each other;
Based on the alternating magnetic field detected by the three-axis magnetic sensor, a progress start position specifying means for specifying a user's progress start position;
Based on the geomagnetism detected by the triaxial magnetic sensor and the gravitational acceleration detected by the triaxial acceleration sensor, a traveling direction identifying means for identifying the traveling direction of the user,
A current position specifying means for specifying the current position of the user when the user moves from the progress start position;
The advancing start position specifying means includes a storage means for storing an arrangement position of the magnetic field generation source and a magnet strength of the magnetic field generation source, and a detection signal of the alternating magnetic field detected by the three-axis magnetic sensor for each frequency. And a frequency separation means for separating the signal into the magnetic field, and calculating the distance from the three-axis magnetic sensor to each of the magnetic field generation sources based on the strength of the alternating magnetic field for each frequency. Identify the starting position,
The current position specifying means detects the user's walking step by step based on a change in acceleration detected by the three-axis acceleration sensor, and the user's stepwise moving direction detected by the moving direction specifying means; Based on the user's stride stored in advance, the user's walking vector for each step is obtained, and all the walking vectors from the progress start position to the current position are added on the map information, thereby the user A portable navigation system that identifies the current position of the mobile phone.   In Claim 1, the said magnetic field generation source is arrange | positioned in the entrance hall provided near the entrance and exit of the building, and the continuous path | route has extended from the entrance hall to the position where the said alternating magnetic field does not reach in the said building. The advancing start position specifying means specifies the advancing start position of the user when the user enters the entrance hall, and the current position specifying means is configured to identify the user when the user enters the aisle. A portable navigation system configured to identify the current position of the mobile navigation system.   3. The portable navigation system according to claim 1, wherein the frequency of the alternating magnetic field is 1 to 40 Hz or 70 to 500 Hz.   4. The portable navigation system according to claim 1, wherein the frequency separation unit separates the AC magnetic field for each frequency by Fourier transform. 5.   5. The portable navigation system according to claim 1, wherein the three-axis magnetic sensor is a magnetic impedance sensor formed by winding a coil around an amorphous wire.

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