JP4761142B2 - Magnetic data processing method, apparatus and program - Google Patents

Description

  The present invention relates to a magnetic data processing method, apparatus, and program, and more particularly to a technique for deriving an offset of a magnetic sensor.

  2. Description of the Related Art Conventionally, a two-dimensional or three-dimensional magnetic sensor that is mounted on a mobile body such as a mobile phone or a vehicle and detects the direction of geomagnetism is known. In general, a magnetic sensor includes two or three magnetic sensor modules for detecting a vector of a magnetic field by decomposing it into directional components orthogonal to each other. The magnetic data that is the output of the magnetic sensor is vector data that is a combination of the outputs of a plurality of magnetic sensor modules. The direction and magnitude indicated by the magnetic data are the direction and magnitude of the magnetic field detected by the magnetic sensor. When the direction or magnitude of geomagnetism is specified based on the output of the magnetic sensor, it is necessary to correct the output of the magnetic sensor in order to cancel measurement errors due to magnetization of the moving body and temperature characteristics of the magnetic sensor itself. The operation value of this correction process is called offset. The offset is vector data representing a magnetic field or the like due to magnetization of the moving body detected by the magnetic sensor, and the measurement error is canceled by subtracting the offset from the magnetic data that is the output of the magnetic sensor. The offset can be derived by determining the center of a circle or sphere in which the magnetic data group is distributed.

  By the way, the distribution of magnetic data is not actually a complete circle or sphere. This is because the output of the magnetic sensor itself has a measurement error according to a Gaussian distribution, and in reality there is no completely uniform magnetic field, so the period in which the magnetic data group necessary to derive the offset is accumulated This is because the magnetic field measured by the magnetic sensor fluctuates, and there is a calculation error until the output of the magnetic sensor is extracted as a digital value. As an algorithm for deriving an offset based on such a magnetic data group, an algorithm using a statistical method such as a least square method is known. When the offset is derived using a statistical method, if the distribution of the magnetic data group as a population is highly biased, an accurate offset cannot be derived, and the number of elements in the population is not large to some extent. Even high-precision offset cannot be derived.

  In Patent Document 1, when magnetic data is stored as a population for deriving an offset by a statistical method, if the distance between magnetic data that are continuously input is short, such magnetic data that has been input is stored. Disclosed is a method for preventing a low-accuracy offset from being derived on the basis of a magnetic data group having a biased distribution by discarding without accumulating it as a population element. When the interval between magnetic data to be accumulated as a population element is increased, the accumulation of the population is completed if the moving body does not change a specific posture (for example, one revolution at a constant angular velocity within a specific time). There is a problem that it takes a long time to complete. However, if the magnetic field in which the moving body is present changes as the moving body moves, the distance between magnetic data output from the magnetic sensor is increased before and after the change of the magnetic field, even if the attitude of the moving body is not changed. Therefore, if the interval between magnetic data to be stored as population elements is narrowed, there is a problem that an offset with low accuracy is derived based on populations including magnetic data output from magnetic sensors in different magnetic fields. .

International Publication No. 2004/003476 Pamphlet

  The present invention was created in view of the above problems, and an object thereof is to provide a magnetic data processing method, apparatus, and program capable of accumulating magnetic data groups for deriving an offset with high accuracy in a short time. .

(1) A magnetic data processing method for achieving the above-described object requires that magnetic data is sequentially input from a magnetic sensor, and the distance between the two input magnetic data exceeds a first threshold value. As described above, the storage of the magnetic data in the storage means starts from the two input magnetic data, and the distance from the magnetic data stored in the storage means is smaller than the first threshold value. On condition that the magnetic data exceeding the threshold value is input, the input magnetic data is additionally stored in the storage means, and the magnetic data is based on the magnetic data stored in the storage means Deriving the offset of.
According to this method, accumulation of the magnetic data group used for deriving the offset is not started unless the distance between the two input magnetic data exceeds the first threshold value. Since the situation in which the magnetic field changes drastically is rare, it can usually occur frequently by setting the first threshold value to a value large enough that the accumulation of magnetic data groups does not start due to the magnetic field change that can normally occur frequently It is possible to prevent the offset from being derived with low accuracy based on the magnetic data group including the magnetic data output from the magnetic sensor before and after a certain change in the magnetic field. If the first threshold value is set in this way and the accumulation of the magnetic data group is started, the trigger is not a magnetic field change that usually occurs frequently, but the posture of the moving object. It is a change. If the number of magnetic data groups necessary for deriving the offset is accumulated within a short period of time after the attitude of the moving body starts to change, the magnetic data groups output from the magnetic sensor can be accumulated within a certain magnetic field. Can do. According to this method, once accumulation of the magnetic data group is started to derive the offset, the threshold value of the distance between the magnetic data to be accumulated and the already accumulated magnetic data is set to the first threshold value. Since the second threshold value is reduced to a smaller second threshold value, the magnetic data group output from the magnetic sensor can be stored in a constant magnetic field within a short time. Further, since the threshold value of the distance between the magnetic data to be stored and the already stored magnetic data is reduced to a second threshold value that is smaller than the first threshold value, the magnetic data is temporarily used to derive the offset. When group accumulation is started, necessary magnetic data groups are accumulated in a short time even if the posture change of the moving body does not follow a specific manner (for example, one revolution at a constant angular velocity within a certain period of time). .

(2) In the magnetic data processing method for achieving the above object, when the input magnetic data is additionally stored in the storage means, the distance from the magnetic data stored last in the storage means is the first The inputted magnetic data may be additionally stored in the accumulating means on condition that the magnetic data exceeding two threshold values is inputted.
According to this method, the distribution of the magnetic data group to be accumulated may be biased, but the necessary magnetic data group is accumulated in a short time.

(3) In the magnetic data processing method for achieving the above object, when the input magnetic data is additionally stored in the storage means, the distance from all the magnetic data stored in the storage means is The input magnetic data may be additionally stored in the storage means on condition that the magnetic data exceeding the second threshold is input.
According to this method, it is possible to prevent the distribution of the data group accumulated to derive the offset from being biased.

(4) In the magnetic data processing method for achieving the above object, one piece of the inputted magnetic data is held before being stored in the storage means, and the distance from the held magnetic data is the first On the condition that the magnetic data below the threshold is continuously input a predetermined number following the stored magnetic data, the stored magnetic data is discarded and the stored magnetic data From the stored magnetic data and the magnetic data input after the stored magnetic data, on condition that the magnetic data exceeding the first threshold is input. The storage of the input magnetic data in the storage means may be started.
According to this method, accumulation of the magnetic data group for deriving the offset can be prevented from being started due to the gradual change of the magnetic field accompanying the movement of the moving body without any change in posture. In particular, when deriving an offset of a three-dimensional magnetic sensor, a group of magnetic data for deriving the offset without prompting the user to make a specific posture change (for example, constant-axis rotational motion with a fixed axis). Therefore, the effect of this method is increased.

(5) In the magnetic data processing method for achieving the above object, the inputted magnetic data is held one before being stored in the storage means, and the distance from the held magnetic data is the first On the condition that the magnetic data below a threshold value is continuously input for a predetermined period following the magnetic data held, the magnetic data held is discarded and the magnetic data held From the stored magnetic data and the magnetic data input after the stored magnetic data, on condition that the magnetic data exceeding the first threshold is input. The storage of the input magnetic data in the storage means may be started.
According to this method, accumulation of the magnetic data group for deriving the offset can be prevented from being started due to the gradual change of the magnetic field accompanying the movement of the moving body without any change in posture. In particular, when the offset of the three-dimensional magnetic sensor is derived, the effect of this method is increased.

(6) In the magnetic data processing method for achieving the above object, a predetermined number of the magnetic data whose distance from the magnetic data stored in the storage means is not more than the second threshold value are continuously input. As a necessary condition, the storage of the magnetic data in the storage means may be resumed after discarding all the magnetic data stored in the storage means.
According to this method, it is possible to prevent magnetic data from being accumulated as a population element for deriving an offset because the magnetic field gradually changes with the movement of the moving body without a change in posture.

(7) In the magnetic data processing method for achieving the above object, the magnetic data whose distance from the magnetic data stored and pushed in the storage means is not more than the second threshold value is continuously input for a predetermined period. As a necessary condition, the storage of the magnetic data in the storage means may be resumed after discarding all the magnetic data stored in the storage means.
According to this method, it is possible to prevent magnetic data from being accumulated as a population element for deriving an offset because the magnetic field gradually changes with the movement of the moving body without a change in posture.

(8) In the magnetic data processing method for achieving the above object, on the basis of the magnetic data stored in the storage means on the condition that a predetermined number of the magnetic data is stored in the storage means An offset of the magnetic data may be derived.
It should be noted that the order of each operation of the method described in the claims is not limited to the order of description as long as there is no technical obstruction factor, and may be executed in any order, or may be executed simultaneously. Also good. In addition, each function of the plurality of means provided in the present invention is realized by a hardware resource whose function is specified by the configuration itself, a hardware resource whose function is specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other. The present invention can be specified not only as a method invention but also as an apparatus invention, a program invention, and a recording medium recording the program.

Hereinafter, embodiments of the present invention will be described in the following order.
A. First embodiment [1. Overall explanation]
1-1. Hardware configuration 1-2. Software configuration [2. Buffer update]
2-1. Overall flow 2-2. Storage start process 2-3. Additional storage processing [3. Derivation of offset]
B. Second Embodiment C. Third Embodiment D. Other embodiments

A. First embodiment [1. Overall explanation]
1-1. Hardware Configuration FIG. 2 is a schematic diagram showing an appearance of a mobile phone 3 which is an example of a mobile body to which the present invention is applied. A three-dimensional magnetic sensor 4 is mounted on the mobile phone 3. The three-dimensional magnetic sensor detects the direction and strength of the magnetic field by detecting the strength of the magnetic field in three directions of x, y, and z orthogonal to each other. Various information such as characters and images is displayed on the display 2 of the mobile phone 3. For example, the display 2 displays a map and an arrow or character indicating the direction.

  FIG. 3 is a block diagram showing a magnetic measurement device including the three-dimensional magnetic sensor 4 and the magnetic data processing device 1. The three-dimensional magnetic sensor 4 includes an x-axis sensor 30, a y-axis sensor 32, and a z-axis sensor 34 that respectively detect an x-direction component, a y-direction component, and a z-direction component of a magnetic field vector due to geomagnetism. The x-axis sensor 30, the y-axis sensor 32, and the z-axis sensor 34 are all configured by a magnetoresistive element, a Hall element, etc., and may be any one as long as it has directivity. The x-axis sensor 30, the y-axis sensor 32, and the z-axis sensor 34 are fixed so that their sensitivity directions are orthogonal to each other. Outputs of the x-axis sensor 30, the y-axis sensor 32, and the z-axis sensor 34 are time-divisionally input to a magnetic sensor I / F (Inter Face) 22. In the magnetic sensor I / F 22, input from the x-axis sensor 30, the y-axis sensor 32, and the z-axis sensor 34 is amplified and then AD converted. Digital magnetic data output from the magnetic sensor I / F 22 is input to the magnetic data processing device 1 via the bus 5.

The magnetic data processing device 1 is a so-called computer including a CPU 40, a ROM 42, and a RAM 44. The CPU 40 is a processor that performs overall control of the mobile phone 3, for example. The ROM 42 is a non-volatile storage medium that stores a magnetic data processing program executed by the CPU 40 and various programs for realizing the function of the moving body, for example, a navigation program. The RAM 44 is a volatile storage medium that temporarily holds data to be processed by the CPU 40 (p ₁ , p ₂ , P _n to be described later), and functions as an accumulation unit. The magnetic data processing device 1 and the three-dimensional magnetic sensor 4 can be configured as a one-chip magnetic measurement device.

1-2. Software Configuration FIG. 4 is a block diagram showing the configuration of the magnetic data processing program 90. The magnetic data processing program 90 is a program for providing azimuth data to the navigation program 98, and is stored in the ROM 42. The azimuth data is two-dimensional vector data indicating the direction of geomagnetism. The orientation data may be provided to other application programs as, for example, three-dimensional vector data for recognizing the posture of the moving body. The magnetic data processing program 90 is composed of a module group such as a buffer management module 92, an offset derivation module 94, and an orientation derivation module 96.

  The buffer management module 92 is a program component that inputs magnetic data sequentially output from the magnetic sensor 4 and accumulates the input magnetic data in a buffer for use in offset updating. The CPU 40, the RAM 44, and the ROM 42 are input means. It functions as an accumulation means, an accumulation start means, and an accumulation continuation means. The buffer may be configured by hardware or software. The magnetic data group stored in this buffer is referred to as a population data group.

  The offset derivation module 94 is a program component that derives a new offset based on the population data group held by the buffer management module 92 and updates the old offset to the new offset. The offset derivation module 94 derives the offset of the CPU 40, the RAM 44, and the ROM 42. It functions as a means. In the context where there is no misunderstanding, the old offset and the new offset are simply referred to as offsets.

  The azimuth derivation module 96 is a program component that corrects the magnetic data sequentially output from the magnetic sensor 4 with the offset held by the offset derivation module 94 to generate azimuth data. Specifically, the azimuth derivation module 96 outputs two or all three of the three components obtained by subtracting each offset component from each component of magnetic data that is three-dimensional vector data as azimuth data. .

  The navigation program 98 is a well-known program that searches for a guidance route to a destination and displays the guidance route on a map. For ease of map recognition, the map is displayed on the screen so that the orientation on the map matches the actual orientation. Therefore, for example, when the mobile phone 3 rotates, the map displayed on the display 2 rotates with respect to the display 2 so as not to rotate with respect to the ground. Direction data is used for such map display processing. Of course, the azimuth data may be used only for displaying east, west, south, and north with characters or arrows.

[2. Buffer update]
2-1. Overall Flow FIGS. 5 and 6 are flowcharts showing the flow of buffer update processing. The processing shown in FIGS. 5 and 6 proceeds when the CPU 40 executes the offset derivation module 94 when an offset update request is generated. The offset update request may be generated at regular time intervals, or may be generated in response to occurrence of a specific event such as user input. The buffer update process includes a front-stage storage start process shown in FIG. 5 and a rear-stage additional storage process shown in FIG.

2-2. Storage start processing In the storage start processing, storage of magnetic data in the buffer is not started due to a magnetic field change that can occur frequently frequently, but storage of the magnetic data in the buffer is started when the posture of the moving body changes greatly. Therefore, a constant A is used as the first threshold value. In addition, in the storage start process, the counter variable m and a constant are stored in order to prevent the magnetic data from being stored in the buffer from being started due to a gradual change in the magnetic field accompanying the movement of the mobile phone 3 without any change in posture. and s are used.

In step S100, the counter variable m is reset to zero.
In step S102, magnetic data q is input from the three-dimensional magnetic sensor 4 to the magnetic data processing device 1, and a data structure q ₁ (q _1x , q _1y , q _1z for holding the first accumulation candidate magnetic data is _obtained. ) Is set.
In step S104, the counter variable m is incremented.
In step S106, magnetic data q is input from the three-dimensional magnetic sensor 4 to the magnetic data processing apparatus 1, and a data structure q ₂ (q _2x , q _2y , q _2z for holding the second accumulation candidate magnetic data is obtained. ) Is set.
In step S108, it is determined whether the distance between the first accumulation candidate magnetic data and the second accumulation candidate magnetic data exceeds the threshold A. That is, it is determined whether or not the following expression (1) is satisfied.
| Q ₁ −q ₂ |> A (1)
If a negative determination is made in step S108, it is determined in step S110 whether the counter variable m has been counted up to a constant s.

As long as the distance between the first accumulation candidate magnetic data and the second accumulation candidate magnetic data does not exceed the threshold A, the processing from step S104 to step S110 is performed until the counter variable m is counted up to a constant s. Repeated. During this period, the data structure q ₂ for holding the second accumulation candidate magnetic data is continuously updated with the last input magnetic data.
When the counter variable m is counted up to the constant s, the process returns to step S100. As a result, in step S102, a magnetic held in the data structures q ₂ for holding data structures q ₁ for holding the accumulated candidate magnetic data of one eye and two eyes of accumulated candidate magnetic data The data is discarded, and the magnetic data held in the data structure q ₁ is updated to the new magnetic data q.

If an affirmative determination is made in step S108, that is, if the distance between the first accumulation candidate magnetic data and the second accumulation candidate magnetic data exceeds the threshold A, the first accumulation candidate magnetic data q ₁ is A data structure P is set in the data structure P ₁ for holding the first population element data, and the second accumulation candidate magnetic data q ₂ is for holding the first population element data. Set to ₂ . That is, the data structure P _n (P _nx , P _ny , P P as a buffer for storing the population data group of the _first storage candidate magnetic data q ₁ and the second storage candidate magnetic data q _{2. nz} ) (n = 1, 2,... u).

  FIG. 1 is an illustration of magnetic data sequentially input to the magnetic data processing apparatus 1. In FIG. 1, a magnetic data group is represented in two dimensions for easy understanding. A magnetic data group input to the magnetic data processing device 1 before and after the magnetic field is changed by the movement of the mobile phone 3 is shown. Each magnetic data is indicated by a white circle and a black circle. The numbers attached to the white and black circles indicate the input order of magnetic data. White circles indicate magnetic data that is not used for derivation of offsets as a population data group, and black circles indicate magnetic data that is used for derivation of offsets as a population data group. Based on FIG. 1, what kind of magnetic data is input will be specifically described as starting accumulation of a magnetic data group as a population data group. The magnetic data sequentially input to the magnetic data processing device 1 are referred to as magnetic data 1, magnetic data 2, magnetic data 3,.

When the magnetic data 1 is input immediately after the buffer update process is started, the magnetic data 1 is held as the _first accumulation candidate magnetic data q ₁ . Subsequently, when the magnetic data 2 and the magnetic data 3 are input, if the distance from the magnetic data 1 to the magnetic data 2 and the magnetic data 3 are both smaller than the threshold value A, the magnetic data 2 and the magnetic data 3 are discarded. Is done. As shown in FIG. 1, in a period in which the attitude of the mobile phone 3 is not greatly changed, the distance from the magnetic data 1 input in the magnetic field before the change to the magnetic data 2 input in the magnetic field before the change. However, the distance d ₃ to the magnetic data 3 input in the changed magnetic field is also smaller than the threshold value A. That is, the threshold A is set so that magnetic data is not started to be stored in the buffer even if the magnetic field changes within a range in which it can frequently occur in a period in which the attitude of the mobile phone 3 does not change significantly. ing. Further, by setting the constants s and "2", i.e., the magnetic data from being held as a storage candidate magnetic data q ₁ of 1 th, the distance from the storage candidate magnetic data q ₁ is equal to or less than the threshold A If two pieces of magnetic data are continuously input, if the accumulation candidate magnetic data q ₁ and q ₂ are discarded, the magnetic data 1 is discarded by inputting the magnetic data 4, and the first accumulation candidate magnetism is obtained. Magnetic data 4 is held as data q ₁ . Of course, the constant s can be set to other than 2.

The magnetic data 4 is input in the magnetic field after the change, and the distance from the magnetic data 4 exceeds the threshold A by the input of the second magnetic data after being held as the _first accumulation candidate magnetic data q _1. When the magnetic data 6 is input, the magnetic data 4 and the magnetic data 6 are stored in the buffer as a population element for deriving an offset. The fact that the magnetic data whose distance from the magnetic data 4 exceeds the threshold A is input in a short period of time is not due to the change in the magnetic field that usually occurs frequently, that is, the attitude of the mobile phone 3 has changed greatly. This means that a change in the relative magnetic field measured from the magnetic sensor 4 has occurred. When the attitude of the mobile phone 3 changes greatly in this way, storage of magnetic data in the buffer is started. In the example shown in FIG. 1, storage of magnetic data in the buffer from the magnetic data 4 and the magnetic data 6 is started.

2-3. Additional Storage Processing In the additional storage processing shown in FIG. 6, a constant B is used as a second threshold value that is smaller than the constant A as the first threshold value in order to accumulate a predetermined number of population data groups in the buffer. That is, as shown in FIG. 1, even if magnetic data is not stored in the buffer because the distance from the previously input magnetic data is short in the storage start process, it is stored in the buffer in the additional storage process. The constant B is set smaller than the constant A. Also in the additional storage process, the counter variable c and the constant t are used so that magnetic data is not accumulated in the buffer because the magnetic field gradually changes as the mobile phone 3 moves without any change in posture. Further, in the additional storage process, a counter variable n is used for ending the accumulation of the population data group when a predetermined number of magnetic data is accumulated.

In step S114, the counter variable n is set to 2. This is because in the additional storage process, the third magnetic data is additionally stored in the buffer.
In step S116, the counter variable c is reset to 0.
In step S118, the counter variable c is incremented.
In step S 120, the magnetic data q output from the three-dimensional magnetic sensor 4 is input to the magnetic data processing device 1.
In step S122, it is determined whether or not the distance between the last magnetic data stored in the buffer, that is, the P _n holding the magnetic data and the last inputted magnetic data q exceeds the threshold value B. That is, it is determined whether or not the following expression (2) is satisfied.
| Q-P _n |> B (2)
If a negative determination is made in step S122, it is determined in step S124 whether the counter variable c has been counted up to a constant t.

  Unless the distance between the magnetic data last stored in the buffer and the magnetic data q last input to the magnetic data processing device 1 exceeds the threshold value B, step S118 is performed until the counter variable c is counted up to a constant t. To step S124 is repeated. When the counter variable c is counted up to the constant t, the process returns to step S100. As a result, all the magnetic data stored in the buffer are discarded in the subsequent processing.

If an affirmative determination is made in step S122, that is, if the distance between the magnetic data stored immediately before in the buffer and the last input magnetic data exceeds the threshold value B, the counter variable n is incremented in step S126 (step S126). S126) The magnetic data q last input to the magnetic data processing device 1 is set in the data structure P _n for holding the n-th population element data (step S128).

  In step S130, it is determined whether the counter variable n has been counted up to u. When the counter variable n has been counted up to u, that is, when u population element data has been accumulated in the buffer, the additional storage processing of magnetic data in the buffer is terminated, and the offset derivation processing is started. . If the counter variable n has not been counted up to u, the process returns to step S116 and the above processing is repeated. The number of population element data necessary for deriving the offset, that is, how many constants u are set is arbitrary. The smaller the constant u and the threshold B, the higher the frequency of updating the offset, which makes it easier for the user to update the offset. As the constant u and the threshold value B are increased, the offset accuracy increases.

[3. Derivation of offset]
Various algorithms for deriving a new offset based on the population data group have been proposed, and may be an algorithm using a statistical method such as the least squares method, or a patent application already filed by the applicant. An algorithm that does not use a statistical method may be used as disclosed in Japanese Patent Application No. 2005-337412 and Japanese Patent Application No. 2006-44289. Regardless of which algorithm is employed, the offset derivation process is executed by the magnetic data processing device 1 based on the magnetic data group stored in the buffer.

B. Second Embodiment In the first embodiment, magnetic data input in the past is used so that the magnetic data is not stored in the buffer because the magnetic field gradually changes as the mobile phone 3 moves without changing its posture. When a predetermined number of magnetic data whose distance to the threshold does not exceed the threshold value is continuously input, the magnetic data input in the past is discarded without being used as population element data. In the second embodiment, in order to achieve the same object, when magnetic data whose distance from the magnetic data input in the past does not exceed the threshold is continuously input for a predetermined period, the magnetic data input in the past is used. Is discarded without being used as population element data. That is, in the second embodiment, when the predetermined timer is up in step S110 of the storage start process and step S124 of the additional storage process, the process returns to step S100.

C. Third Embodiment In the first embodiment, in the additional storage process, unless the distance between the magnetic data last stored in the buffer and the last input magnetic data exceeds the threshold value B, the last input is performed. An algorithm is described in which the stored magnetic data is not stored in the buffer. In this case, even though magnetic data that is close to the last input magnetic data is already stored in the buffer, the last input magnetic data may be additionally stored in the buffer. There is a possibility that the distribution of the group data group is biased. Therefore, in the third embodiment, unless the distance between all the magnetic data stored in the buffer and the last input magnetic data exceeds the threshold value B, the last input magnetic data is stored in the buffer. An algorithm that is not stored is employed. Specifically, in the process of step S122, the comparison target with the last input magnetic data q is P _k (k = 1, 2,... N), and the following equation (3) is obtained for all k. If not satisfied, the process proceeds to step S124.
| Q-P _k |> B (3)
According to the third embodiment, since the offset is not derived based on the population data group including the magnetic data that are close to each other, the offset can be derived with high accuracy.

D. Other Embodiments The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist thereof. For example, the present invention is naturally applicable to a magnetic sensor mounted on a PDA or a magnetic sensor mounted on a vehicle. Of course, the present invention can be applied to a two-dimensional magnetic sensor.

The schematic diagram which concerns on embodiment of this invention. The schematic diagram which concerns on embodiment of this invention. The block diagram which concerns on embodiment of this invention. The block diagram which concerns on embodiment of this invention. The flowchart which concerns on 1st embodiment of this invention. The flowchart which concerns on 1st embodiment of this invention.

Explanation of symbols

1: Magnetic data processing device, 3: Mobile phone (mobile), 4: Three-dimensional magnetic sensor, 44: RAM (storage means), 90: Magnetic data processing program, 92: Buffer management module (storage start means, storage) (Continuation means), 94: offset derivation module (derivation means)

Claims (10)

Magnetic data is sequentially input from the magnetic sensor mounted on the moving body,
Storage of the magnetic data in the storage means is started from the two input magnetic data, on condition that the distance between the two input magnetic data exceeds the first threshold value,
On the condition that the magnetic data having a distance from the magnetic data stored in the storage means exceeding a second threshold value smaller than the first threshold value is input, the inputted magnetic data is Additionally stored in the storage means;
Deriving an offset of the magnetic data based on the magnetic data stored in the storage means;
Magnetic data processing method. When additionally storing the inputted magnetic data in the storage means, it is necessary that the magnetic data whose distance from the last stored magnetic data in the storage means exceeds the second threshold value is input As a condition, the input magnetic data is additionally stored in the storage means.
The magnetic data processing method according to claim 1. When the input magnetic data is additionally stored in the storage means, the magnetic data whose distance from all the magnetic data stored in the storage means exceeds the second threshold is input. As a necessary condition, the input magnetic data is additionally stored in the storage means.
The magnetic data processing method according to claim 1. Hold one of the input magnetic data before storing in the storage means,
Retained on condition that a predetermined number of magnetic data whose distance from the retained magnetic data is less than or equal to the first threshold value is continuously input following the retained magnetic data Discard the magnetic data;
Input after the stored magnetic data and the stored magnetic data, on condition that the magnetic data whose distance from the stored magnetic data exceeds the first threshold is input. Starting storage of the input magnetic data in the storage means from the magnetic data
The magnetic data processing method as described in any one of Claims 1-3. Hold one of the input magnetic data before storing in the storage means,
The stored data is stored on condition that the distance from the stored magnetic data is continuously input for a predetermined period following the magnetic data in which the magnetic data having the first threshold value or less is stored. Discard magnetic data,
Input after the stored magnetic data and the stored magnetic data, on condition that the magnetic data whose distance from the stored magnetic data exceeds the first threshold is input. Starting storage of the input magnetic data in the storage means from the magnetic data
The magnetic data processing method as described in any one of Claims 1-3. All the data stored in the storage means are provided on the condition that a predetermined number of the magnetic data whose distance from the magnetic data stored in the storage means is less than or equal to the second threshold value are continuously input. Resuming storage of the magnetic data in the storage means after discarding the magnetic data;
The magnetic data processing method as described in any one of Claims 1-5. All the above-mentioned stored in the storage means on the condition that the magnetic data whose distance to the magnetic data stored in the storage means is continuously input for a predetermined period of time is less than the second threshold value Resuming storage of the magnetic data in the storage means after discarding the magnetic data;
The magnetic data processing method as described in any one of Claims 1-5. Deriving an offset of the magnetic data based on the magnetic data stored in the storage means on the condition that a predetermined number of the magnetic data is stored in the storage means;
The magnetic data processing method as described in any one of Claims 1-7. Input means for sequentially inputting magnetic data output from a magnetic sensor mounted on a moving body;
Storage means for storing the inputted magnetic data;
Accumulation starting from the two input magnetic data, storing the magnetic data in the storage means, provided that the distance between the two input magnetic data exceeds a first threshold. Starting means;
On the condition that the magnetic data having a distance from the magnetic data stored in the storage means exceeding a second threshold value smaller than the first threshold value is input, the inputted magnetic data is Accumulation continuation means for additionally storing in the accumulation means;
Derivation means for deriving an offset of the magnetic data based on the magnetic data stored in the storage means;
A magnetic data processing apparatus comprising: Input means for sequentially inputting magnetic data output from a magnetic sensor mounted on a moving body;
Storage means for storing the inputted magnetic data;
Accumulation starting from the two input magnetic data, storing the magnetic data in the storage means, provided that the distance between the two input magnetic data exceeds a first threshold. Starting means;
On the condition that the magnetic data having a distance from the magnetic data stored in the storage means exceeding a second threshold value smaller than the first threshold value is input, the inputted magnetic data is Accumulation continuation means for additionally storing in the accumulation means;
Derivation means for deriving an offset of the magnetic data based on the magnetic data stored in the storage means;
A magnetic data processing program that causes a computer to function.

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