Position estimation device, position estimation method, program

Abstract

To provide a position estimation device that can perform highly accurate position estimation even under an environment having a wide position detection range.SOLUTION: A position estimation device causes a plurality of pieces of magnetic field generation means arranged in different positions to generate magnetic field one by one in sequence; acquires a magnetic vector value of each magnetic field generated one by one in sequence, which magnetic vector value is detected by a magnetic sensor; derives a vector angle that is an angle between magnetic vectors of each magnetic field, on the basis of the acquired magnetic vector value; and estimates a position of the magnetic sensor on the basis of a comparison result between predetermined reference vector angles Φt, Θt and Ψt that are vector angle references made by magnetic vectors of each magnetic field in each position of a coordinate space in which each magnetic field is generated, and the derived vector angle.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a position estimation device, a position estimation method, and a program used for, for example, motion capture. [Background technology]

[0002] As a conventional position detection device for sensing the movement of a human body, for example, Patent Document 1 describes a magnetic position detection device that includes a magnetic sensor that can detect changes in an external magnetic field and a magnetic field generating unit (e.g., a magnet) that can change its position relative to the magnetic sensor, and acquires the position of the magnetic sensor based on a sensor signal output from the magnetic sensor in response to changes in the external magnetic field. In this device, the position of the tongue can be determined by measuring the accurate absolute positions of a magnetic field source attached inside the mouth and a magnetic sensor attached to the tongue. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-34510 Summary of the Invention [Problem to be solved by the invention]

[0004] Magnetic position detection devices have relatively high position detection accuracy compared to other types such as optical and inertial types used in motion capture, etc., because they are less susceptible to errors caused by physical factors such as obstructions and environmental factors such as the amount of drift. However, conventional technologies have issues such as the detection results being affected by the strength of the magnetic force and obstacles, and the range in which position can be detected being narrow, because they measure a single distance between the generated magnetic field and the magnetic sensor.

[0005] In view of the above, an object of the present invention is to provide a position estimation device, a position estimation method, and a program that are capable of performing highly accurate position estimation even in an environment with a wide position detection range. [Means for solving the problem]

[0006] The position estimation device of the present invention comprises a magnetic field control means for causing multiple magnetic field generating means arranged at different positions to generate magnetic fields one by one in sequence, a vector value acquisition means for acquiring magnetic vector values ​​of each of the magnetic fields generated one by one in sequence, which are magnetic vector values ​​detected by a magnetic sensor, an angle derivation means for deriving a vector angle, which is the angle between the magnetic vectors of each of the magnetic fields, based on the acquired magnetic vector values, and a position estimation means for estimating the position of the magnetic sensor based on the comparison result between the derived vector angle and a predetermined reference vector angle that serves as a basis for the vector angle between the magnetic vectors of each of the magnetic fields at each position in the coordinate space where each of the magnetic fields is generated.

[0007] In the position estimation method of the present invention, multiple magnetic field generating means arranged at different positions are caused to generate magnetic fields one by one in sequence, the magnetic vector values ​​of each magnetic field generated one by one in sequence and detected by a magnetic sensor are acquired, a vector angle, which is the angle between the magnetic vectors of each magnetic field, is derived based on the acquired magnetic vector values, and the position of the magnetic sensor is estimated based on the comparison result between the derived vector angle and a predetermined reference vector angle that serves as a basis for the vector angle formed by the magnetic vectors of each magnetic field at each position in the coordinate space where each magnetic field is generated.

[0008] The program of the present invention is a program executed by a computer, and realizes the following processes: a process of causing multiple magnetic field generating means arranged at different positions to generate magnetic fields one by one in sequence; a process of acquiring magnetic vector values ​​of each magnetic field generated one by one in sequence, which are detected by a magnetic sensor; a process of deriving a vector angle, which is the angle between the magnetic vectors of each magnetic field, based on the acquired magnetic vector values; and a process of estimating the position of the magnetic sensor based on the comparison result between the derived vector angle and a predetermined reference vector angle that serves as a basis for the vector angle formed by the magnetic vectors of each magnetic field at each position in the coordinate space where each magnetic field is generated. [Effects of the Invention]

[0009] According to the present invention, highly accurate position estimation is possible even in an environment where the position detection range is wide. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a motion capture device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of the motion capture device shown in FIG. 1. [Figure 3] FIG. 10 is a diagram showing coordinate positions relative to a magnetic field generating unit that acquires magnetic vectors. [Figure 4] FIG. 10 is a diagram showing a coordinate space in which multiple magnetic field generating units are arranged. [Figure 5] FIG. 1 is a diagram showing the magnetic vectors and vector angles of three magnetic fields. [Figure 6] 10 is a flowchart illustrating a position estimation operation in the position estimation device. [Figure 7] FIG. 10 is a diagram illustrating an example of a magnetic vector when estimating a posture. [Figure 8] 10 is a flowchart illustrating a modified example of the position estimation operation in the position estimation device. [Figure 9]FIG. 10 is a diagram showing an example of a procedure for calculating a magnetic vector from which a geomagnetic component has been removed. [Figure 10] FIG. 2 is a block diagram showing a modified example of the motion capture device shown in FIG. [Figure 11] FIG. 2 is a block diagram showing a modified example of the motion capture device shown in FIG. [Figure 12] FIG. 2 is a block diagram showing a modified example of the motion capture device shown in FIG. [Figure 13] FIG. 2 is a block diagram showing a modified example of the motion capture device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described below with reference to the drawings. The motion capture device of this embodiment is a magnetic type. As shown in FIG. 1, the motion capture device is composed of three magnetic field generating units, namely, first magnetic field generating unit 11a to third magnetic field generating unit 11c (hereinafter collectively referred to as magnetic field generating units), for generating multiple magnetic fields in space; multiple sensor units 21 (indicated by black circles in the figure) that are attached to the body M of a user who is the subject of motion capture and detect the multiple magnetic fields generated by each magnetic field generating unit; and a position estimation device 31 that wirelessly communicates with each magnetic field generating unit 11a to 11c and each sensor unit 21. Note that it is sufficient for there to be more than one magnetic field generating unit to generate multiple magnetic fields in space. That is, the number of magnetic field generating units needs to be at least two, but may be four or more.

[0012] As shown in FIG. 2, each of the magnetic field generating units 11a to 11c includes an electromagnet 12, a communication unit 13, a control unit 14, and a battery 15 that supplies operating power thereto. In response to a magnetic field generation command sent from the position estimation device 31 via the communication unit 13, the control unit 14 generates a magnetic field by energizing the electromagnet 12 from the battery 15 at a predetermined timing, and in response to a magnetic field stop command sent from the position estimation device 31, stops energizing the electromagnet 12 to stop generating the magnetic field. The control unit 14 also sends the status (operating state) of each of the magnetic field generating units 11a to 11c to the position estimation device 31 via the communication unit 13. Here, each of the magnetic field generating units 11a to 11c may have any configuration other than that shown in the figure, as long as it can be configured so that the generation of a magnetic field can be turned on and off by the position estimation device 31.

[0013] Each sensor unit 21 includes a magnetic sensor 22, a communication unit 23, a control unit 24, and a battery 25 that supplies operating power to these units. The magnetic sensor 22 is a three-axis magnetic sensor that detects vector values ​​indicating the direction and strength of the magnetic fields generated by each of the magnetic field generating units 11a to 11c. The control unit 24 causes the magnetic sensor 22 to detect the magnetic field at a predetermined timing in response to a magnetic field detection command sent from the position estimation device 31 via the communication unit 23. Furthermore, based on the detection result of the magnetic sensor 22, the control unit 24 obtains the state of the magnetic field at any position in space, i.e., a magnetic vector indicating the magnetic field strength and the direction of the magnetic field lines, and sends this to the control unit 24 as sensor data.

[0014] The position estimation device 31 includes a communication unit 32, a control unit 33, a map storage unit 34, an input / output unit 35, and a power supply unit 36 ​​that supplies operating power to these units. The position estimation device 31 communicates with each magnetic field generation unit 11 and each sensor unit 21 via the communication unit 32. The control unit 33 controls the generation and stopping of magnetic fields in each magnetic field generation unit 11a to 11c at predetermined timing by sending the generation command. The control unit 33 also sends the detection command to each sensor unit 21 to detect magnetic field vector values ​​and acquire sensor data from each sensor unit 21. The control unit 33 also calculates the coordinate position of each sensor unit 21 in the space where each magnetic field generation unit 11a to 11c generates a magnetic field based on the detection results acquired from each sensor unit 21. The map storage unit 34 stores map information of the magnetic field used as a reference when acquiring the coordinate position of each sensor unit 21. This map information includes two types of information: a vector map and a vector angle map, as described below. The input / output unit 35 is a user interface used to operate the position estimation device 31.

[0015] Here, the position estimation device 31 is realized by various information processing devices, such as various PCs, smartphones, VR goggles, etc., capable of data communication with each of the magnetic field generating units 11a to 11c and each of the sensor units 21. In this case, the map storage unit 34 is realized by any storage medium, such as a ROM or RAM, provided in the information processing device. Furthermore, the control unit 33 is realized, for example, by a CPU or the like provided in the information processing device executing predetermined processing in accordance with a program pre-stored in the storage medium, i.e., a program used for motion capture. Note that, if the position estimation device 31 is, for example, a device dedicated to motion capture, the control unit 33 may be configured to be realized by hardware.

[0016] In the motion capture device of this embodiment, the magnetic field generating units 11a to 11c are caused to generate magnetic fields one by one in order, and the magnetic vectors of each magnetic field are acquired by each sensor unit 21, thereby detecting the position and posture of each sensor unit 21 attached to the body M and detecting the movement of each sensor unit 21. In this case, the above-mentioned map information is stored in advance in the map storage unit 34 of the position estimation device 31 by the following procedure.

[0017] More specifically, first, a reference magnetic vector, which is a magnetic vector of each magnetic field generated by the first magnetic field generating unit 11a to the third magnetic field generating unit 11c and serves as a reference, is acquired individually at coordinate positions P1, P2,..., Pn-1, Pn, based on each magnetic field generating unit 11a to 11c as shown in FIG. 3. At this time, each magnetic field generating unit 11a to 11c is individually driven to generate a single magnetic field in an environment free from the influence of the earth's magnetism (e.g., a magnetically shielded space). This reference magnetic vector may be acquired using a single sensor unit 21 or multiple sensor units 21. However, the orientation of the sensor unit 21 relative to each magnetic field generating unit 11a to 11c is the same at each position. A vector map consisting of the acquired data group is then stored as map information in the map storage unit 34. The data for each coordinate Pn may include position data of the starting point of the vector based on each magnetic field generating unit 11a to 11c. Furthermore, the vector map does not have to be obtained from actual detection data, but can be obtained by calculation, or, if magnetic vectors are detected in an environment where the influence of geomagnetic field is known, can be obtained from data after excluding the influence of geomagnetic field from the actual detection data.

[0018] In the case of three magnetic field generating units as in this embodiment, the data stored as a vector map is, for example, data expressed as follows: That is, the vector map relating to the magnetic field generated by the first magnetic field generating unit 11a is:

number

number

number

[0019] Furthermore, prior to actually performing motion capture, the user is prompted to input the positional relationship of the magnetic field generating units 11a to 11c. For example, if the magnetic field generating units 11a to 11c are to be installed on a flat surface such as a floor, the user is prompted to input the distance between them. This determines the coordinate space S shown in FIG. 4, i.e., the space in which the first to third magnetic field generating units 11a to 11c are arranged and the space in which the positions of the sensor units 21 are to be detected. Note that information regarding the positional relationship of the magnetic field generating units 11a to 11c may be automatically acquired by the position estimation device 31 without requiring the user to input it. In this case, for example, distance sensors for measuring the distances between the magnetic field generating units 11a to 11c may be separately provided in all or any two of the magnetic field generating units 11a to 11c, and the measurement results (distances) of the distance sensors may be sent to the position estimation device 31.

[0020] Subsequently, after the coordinate space S is determined, the vector angles, which are the angles formed by the magnetic vectors (vectors A, B, and C) of the three magnetic fields at each position P1, P2,..., Pn-1, Pn in the coordinate space S, are calculated based on the positions and vector map of each magnetic field generating unit 11a-11c. That is, the angle Φt between vectors A and B, the angle Θt between vectors B and C, and the angle Ψt between vectors C and A are calculated. Then, a vector angle map consisting of the vector angles (hereinafter referred to as reference vector angles) at each position is stored as map information in the map storage unit 34. The reference vector angles serve as a reference when acquiring the position of each sensor unit 21. Note that if the number of magnetic field generating units, i.e., the number of magnetic fields generated in the coordinate space S, is four, for example, there will be four types of magnetic vectors at each position in the coordinate space S, and therefore six types of reference vector angles at each position.

[0021] Next, the processing procedure of the control unit 33 of the position estimation device 31 when acquiring the position of each sensor unit 21 with the above-mentioned map information stored in the map storage unit 34 will be described with reference to Fig. 6. First, the control unit 33 selects a magnetic field generation unit that generates a magnetic field in a time-division manner (step S1). In this embodiment, the order in which the magnetic fields are generated is the first magnetic field generation unit 11a, the second magnetic field generation unit 11b, and the third magnetic field generation unit 11c, and in this example, the first magnetic field generation unit 11a is selected.

[0022] Then, while the magnetic field generating units 11a to 11c are not generating a magnetic field, the control unit 33 sends a detection command to the sensor unit 21 to cause the magnetic sensor 22 to detect the earth's magnetic field, and stores the detected magnetic vector, i.e., the magnetic vector indicating the magnetic field environment (step S2). Next, the control unit 33 sends a magnetic field generation command to the first magnetic field generating unit 11a, causing the first magnetic field generating unit 11a to energize the electromagnet 12 and generate the first magnetic field (step S3), and then waits a certain time (e.g., several milliseconds) until the magnetic field stabilizes (step S4). After waiting for this time, the control unit 33 sends a detection command to the sensor unit 21 to cause the magnetic sensor 22 to detect the first magnetic field, and stores the detection result (magnetic vector) (step S5).

[0023] Subsequently, the control unit 33 sends a magnetic field stop command to the first magnetic field generating unit 11a, causing the first magnetic field generating unit 11a to stop energizing the electromagnet 12 (step S6).Then, the control unit 33 sequentially changes the magnetic field generating unit that generates the magnetic field (step S8) until the magnetic field generation by each of the magnetic field generating units 11a to 11c has completed (step S7: NO), and repeats the processes of steps S2 to S7 described above.

[0024] Then, when the magnetic field generation units 11a to 11c have completed a cycle of generating magnetic fields, i.e., when the magnetic vectors of each magnetic field have been acquired (step S7: YES), the control unit 33 corrects the magnetic vectors of each magnetic field acquired in step S5 (step S9). This correction is intended to eliminate the influence of the geomagnetic field, which affects the magnetic vectors of each magnetic field in a typical environment. Specifically, by calculating the difference between the magnetic vector of each magnetic field and the magnetic vector of the geomagnetic field (the magnetic vector indicating the magnetic field environment) acquired in step S2, the magnetic vector of each magnetic field is corrected to a magnetic vector that is not affected by the geomagnetic field, i.e., a magnetic vector from which the geomagnetic component has been removed.

[0025] Next, the control unit 33 calculates the vector angle between each magnetic field based on the corrected magnetic vector (step S10). This vector angle is the same as the vector angle stored as a vector angle map in the map storage unit 34, and is the angle between the magnetic vectors of each magnetic field. Thereafter, the control unit 33 compares the calculated vector angle with the reference vector angle stored as the vector angle map to estimate the coordinate position of the sensor unit 21 (step S11).

[0026] Specifically, the control unit 33 first calculates the difference between the current vector angle (combination of three vector angles: Φr, Θr, Ψr) and the reference vector angle (combination of three vector angles: Φt, Θt, Ψt) of each position in the vector angle map at each position P1, P2, Pn-1, Pn in the coordinate space S, i.e.,

number

[0027] In this way, by comparing the current vector angle with a reference vector angle stored in advance during the above processing, the coordinate position of the sensor unit 21 can be obtained even if the attitude of the sensor unit 21 relative to each magnetic field generating unit 11a to 11c has not been determined and the attitude of the sensor unit 21 is unknown.

[0028] Subsequently, the control unit 33 compares the current magnetic vector with the reference magnetic vector of the coordinate position estimated previously, and estimates the attitude of the sensor unit 21 (step S12). Specifically, the control unit 33 compares one of the corrected magnetic vectors acquired in step S9, i.e., the orientation of the magnetic vector of the magnetic field generated by any of the magnetic field generating units 11a to 11c, with the orientation of the reference magnetic vector of the same magnetic field stored as a vector map, at the coordinate position estimated previously, calculates the twist of the attitude of the sensor unit 21 from the angle between them, and identifies the attitude of the sensor unit 21 based on this.

[0029] 7A and 7B are diagrams showing an example of magnetic vectors of a magnetic field at a specific coordinate position, and the magnetic vector V0 shown in Fig. 7A is a reference magnetic vector stored as a vector map, and the magnetic vector V1 shown in Fig. 7B is a corrected magnetic vector obtained in step S9. In the process of step S12, the twist in the attitude of the sensor unit 21 is calculated from the angle θ formed by both vectors V0 and V1 shown in Fig. 7B.

[0030] Thereafter, the control unit 33 repeats the above-described process to estimate the coordinate position and orientation of the sensor unit 21 at the time of detection, thereby detecting the movement of the sensor unit 21. Note that the above-described process is performed simultaneously in parallel for each sensor unit 21.

[0031] In the present embodiment described above, the first magnetic field generating unit 11a to the third magnetic field generating unit 11c are caused to generate magnetic fields one by one in sequence, the magnetic vectors of each of these magnetic fields are acquired by the magnetic sensor 22 of the sensor unit 21, and the vector angles Φr, Θr, Ψr, which are the angles formed by the magnetic vectors of each of the acquired magnetic fields, are acquired.The position of the magnetic sensor 22 (sensor unit 21) is estimated based on the results of comparing these vector angles with the previously acquired reference vector angles Φt, Θt, Ψt formed by the magnetic vectors A, B, C that serve as the references for each magnetic field at each position in the coordinate space that detects the position of the magnetic sensor 22 (sensor unit 21).

[0032] Here, the vector angle, which is the angle between the magnetic vectors of each magnetic field, is magnetic field information determined according to the relative positions of the magnetic field generating units 11a-11c. Therefore, position detection is possible even when the distance between each magnetic field generating unit 11a-11c and the magnetic sensor 22 is large and the strength of the detected magnetic field is weak. Furthermore, since the position is estimated based on the comparison result between the vector angle acquired during position detection and a reference vector angle acquired in advance, the degree to which the detection result is affected by obstacles is extremely small. Therefore, highly accurate position estimation can be performed even in an environment with a wide position detection range. Furthermore, it is sufficient to use multiple magnetic field generating units, and increasing the number of magnetic field generating units makes it easier to perform more accurate position estimation.

[0033] Furthermore, in this embodiment, when detecting a position, the position estimation device 31 causes the magnetic sensor 22 of the sensor unit 21 to acquire a magnetic vector indicating the magnetic field environment before each magnetic field is generated by each of the magnetic field generating units 11a to 11c, corrects the magnetic vector of each magnetic field based on the acquired magnetic vector, and acquires the vector angle of each magnetic field from the magnetic vector of each magnetic field after the correction. Therefore, even in a general environment where each magnetic field is affected by geomagnetism when detecting each magnetic field, more accurate position estimation can be performed.

[0034] In this embodiment, the position estimation device 31 includes a map storage unit 34 that stores reference vector angles Φt, Θt, and Ψt at each position in the coordinate space S in advance. The position of the magnetic sensor 22 (sensor unit 21) is estimated based on a comparison result between the reference vector angles Φt, Θt, and Ψt at each position stored in the map storage unit 34 and each vector angle acquired during position detection. Therefore, for example, by setting the distances between the magnetic field generation units 11a to 11c during position detection to predetermined distances, the user's workload prior to position detection can be reduced. In this case, multiple combination patterns of distances between the magnetic field generation units 11a to 11c during position detection may be prepared, and the reference vector angles corresponding to each combination pattern may be stored in the map storage unit 34. The user may then select one of the combination patterns during position detection.

[0035] In this embodiment, the position estimation device 31 estimates the attitude of the magnetic sensor 22 based on the magnetic vector of any magnetic field among the magnetic fields generated by the magnetic field generating units 11a to 11c, which is acquired by the magnetic sensor 22 of the sensor unit 21, and a reference magnetic vector, which is a reference magnetic vector acquired in advance for the magnetic field and whose position corresponds to the previously estimated position of the magnetic sensor 22 (sensor unit 21). Therefore, by using only the data acquired during position detection, it is possible to efficiently detect the attitude of the magnetic sensor 22 as well as its position.

[0036] Here, a modification of this embodiment will be described. In this embodiment, when acquiring the position of each sensor unit 21, a correction is performed to remove the geomagnetic component from the magnetic vector of each detected magnetic field, and the vector angle of each magnetic field is acquired from the corrected magnetic vector, thereby enabling more accurate position estimation. However, since the magnetic vector of each detected magnetic field is also affected by magnetic noise other than the geomagnetic field, removing this influence from the magnetic vector of each magnetic field enables even more accurate position estimation.

[0037] To remove magnetic noise other than that of the earth's magnetism, for example, when acquiring magnetic vectors for each magnetic field (step S5 in FIG. 6), the magnetic vectors may be acquired multiple times, the average of the acquired multiple magnetic vectors may be calculated, and the averaged magnetic vector may be used as the detection result. Alternatively, for example, multiple magnetic sensors 22 may be provided in each sensor unit 21, and multiple magnetic vectors acquired by the multiple magnetic sensors 22 for each magnetic field may be averaged, and the averaged magnetic vector may be used as the detection result.

[0038] On the other hand, in this embodiment, the geomagnetic component is removed from the magnetic vector of each magnetic field by correcting the magnetic vector of each magnetic field using the magnetic vector of the geomagnetic field that was actually detected, but it is also possible to obtain a magnetic vector from which the geomagnetic component has been removed without actually detecting the magnetic vector of the geomagnetic field.

[0039] In this case, for example, by adding a switch circuit or the like to each of the magnetic field generating units 11a to 11c that switches the direction of current when energizing the electromagnet 12, each of the magnetic field generating units 11a to 11c is configured to generate two types of magnetic fields with different magnetic field directions in response to a magnetic field command sent from the position estimation device 31. Then, when acquiring the position of the sensor unit 21, the control unit 33 of the position estimation device 31 is caused to perform the processing shown in Fig. 8.

[0040] The processing of the control unit 33 will be described below. The control unit 33 first selects a magnetic field generating unit that generates a magnetic field in a time-sharing manner (step S51). Next, the control unit 33 sends a magnetic field generation command to the first magnetic field generating unit 11a, causing the first magnetic field generating unit 11a to generate a magnetic field (step S52), and then waits a certain period of time (e.g., several milliseconds) until the magnetic field stabilizes (step S53). After this wait, the control unit 33 causes the magnetic sensor 22 to detect the magnetic field, acquires the detection result at this time as a first magnetic vector Va (see FIG. 9(a)), and stores it (step S54). This first magnetic vector Va is different from the accurate magnetic vector Va1 of the magnetic field generated by the first magnetic field generating unit 11a, and is influenced by the earth's magnetism (see FIG. 9(c)).

[0041] Next, the control unit 33 sends a command to the first magnetic field generating unit 11a to switch the direction of the current flowing through the electromagnet 12, thereby reversing the direction of the magnetic field as shown in FIG. 9(b) (step S55), and again waits a certain period of time (e.g., several milliseconds) until the magnetic field stabilizes (step S56). After this wait, the control unit 33 causes the magnetic sensor 22 to detect the magnetic field again, acquires the detection result at this time as a second magnetic vector Vb, and stores it (step S57). This second magnetic vector Vb is also different from the accurate magnetic vector Vb1 of the magnetic field generated by the first magnetic field generating unit 11a and is influenced by the earth's magnetic field (see FIG. 9(c)).

[0042] Next, the control unit 33 calculates the geomagnetic vector Vn shown in FIG. 9(c) by calculating the difference between the first magnetic vector Va and the second magnetic vector Vb (step S58), and then corrects the first magnetic vector Va using the calculated value (step S59). Specifically, the control unit 33 subtracts the vector component of the geomagnetic field from the first magnetic vector Va to obtain a magnetic vector from which the geomagnetic component has been removed and stores the obtained vector. In other words, the control unit 33 obtains and stores the magnetic vector from which the geomagnetic component has been removed without actually detecting the geomagnetic vector. Note that the magnetic vector to be corrected here may be the second magnetic vector Vb. Also, FIG. 9(c) merely illustrates the magnetic vectors (Va, Vb, Va1, Vb2, Vn) for the sake of convenience. The control unit 33 then sends a magnetic field stop command to the first magnetic field generating unit 11a, causing the first magnetic field generating unit 11a to stop energizing the electromagnet 12 (step S60).

[0043] The control unit 33 then sequentially switches the magnetic field generating unit that generates the magnetic field (step S62) and repeats the processes of steps S52 to S61 described above until each of the magnetic field generating units 11a to 11c has completed its cycle of magnetic field generation (step S61: NO). Once each of the magnetic field generating units 11a to 11c has completed its cycle of magnetic field generation and the magnetic vectors of each magnetic field have been acquired (step S61: YES), the control unit 33 calculates the vector angle between each magnetic field based on the magnetic vectors of each magnetic field from which the geomagnetic component has been removed, acquired in step S59 (step S62). Thereafter, the control unit 33 performs the same processes as steps S11 and S12 of FIG. 6 described above, and estimates the attitude of the sensor unit 21 (steps S63 and S64).

[0044] Furthermore, in the above-described embodiment, the magnetic field generating units 11a to 11c and the sensor units 21 are wirelessly connected to the position estimation device 31. However, the magnetic field generating units 11a to 11c and the sensor units 21 may be wired and connected to the position estimation device 31. In this case, the batteries 15, 25 of the magnetic field generating units 11a to 11c and the sensor units 21 may be eliminated, and the operating power thereof may be supplied from the position estimation device 31.

[0045] In the above-described embodiment, the position estimation device 31 is configured to send a magnetic field detection command to each sensor unit 21 and acquire sensor data from each sensor unit 21. However, as shown in Fig. 8, for example, a configuration may be adopted in which each of the magnetic field generation units 11a to 11c is capable of communicating with each of the sensor units 21, and the position estimation device 31 sends a magnetic field detection command to each sensor unit 21 via each of the magnetic field generation units 11a to 11c and acquires sensor data from each of the sensor units 21 via each of the magnetic field generation units 11a to 11c. In this case, by connecting each of the magnetic field generation units 11a to 11c to the position estimation device 31 via a wired connection, the battery 15 of each of the magnetic field generation units 11a to 11c can be eliminated, and their operating power can be supplied from the position estimation device 31.

[0046] 9, for example, the magnetic field generating units 11a to 11c may be configured to be able to communicate with the sensor units 21, and the position estimation device 31 may send magnetic field generation commands and stop commands to the magnetic field generating units 11a to 11c via at least one of the sensor units 21. In this case, by connecting the sensor units 21 to the position estimation device 31 via a wired connection, the battery 25 of each sensor unit 21 may be eliminated, and the operating power for the sensor units 21 may be supplied from the position estimation device 31.

[0047] In the above-described embodiment, a configuration has been described in which a position estimation device 31 is provided separately from each of the magnetic field generation units 11a to 11c and each of the sensor units 21. However, the position estimation device 31 may be eliminated, and its equivalent function may be realized by any one of the magnetic field generation units 11a to 11c or any one of the sensor units 21. That is, FIG. 10 is a diagram showing an example in which the function of the control unit 33 of the position estimation device 31 is realized by the control unit 14 of the first magnetic field generation unit 11a. In this case, the first magnetic field generation unit 11a needs to be newly provided with a map storage unit 16 similar to that described above. Furthermore, the control unit 14 sends magnetic field generation commands and stop commands to the other magnetic field generation units 11b and 11c, while sending magnetic field detection commands to each of the sensor units 21 and acquiring sensor data from each of the sensor units 21.

[0048] 11 is a diagram showing an example of a case where the functions of the control unit 33 of the position estimation device 31 are realized by the control unit 24 of a specific sensor unit 21. In this case, the sensor unit 21 needs to be newly provided with a map storage unit 26 similar to that described above. The control unit 24 also sends magnetic field detection commands to the other sensor units 21 and acquires sensor data from the other sensor units 21, while sending magnetic field generation commands and stop commands to each of the magnetic field generating units 11a to 11c.

[0049] The above describes the embodiments and modifications of the present invention, but the present invention is not limited to these and includes the inventions set forth in the claims and their equivalents. [Explanation of symbols]

[0050] 11a...first magnetic field generating unit, 11b...second magnetic field generating unit, 11c...third magnetic field generating unit, 12...electromagnet, 21...sensor unit, 22...magnetic sensor, 31...position estimation device, 33...control unit, 34...map storage unit, M...body, S...coordinate space

Claims

1. a magnetic field control means for causing a plurality of magnetic field generating means disposed at different positions to generate magnetic fields one by one in sequence; a vector value acquiring means for acquiring magnetic vector values ​​of the magnetic fields generated one by one and detected by a magnetic sensor; An angle deriving means for deriving a vector angle, which is an angle between the magnetic vectors of the magnetic fields, based on the acquired magnetic vector values; a position estimation means for estimating a position of the magnetic sensor based on a comparison result between a predetermined reference vector angle serving as a reference for a vector angle formed by magnetic vectors of the magnetic fields at each position in a coordinate space where the magnetic fields are generated and the derived vector angle; A position estimation device comprising:

2. the vector value acquisition means causes the magnetic sensor to acquire a magnetic vector value indicating a magnetic field environment prior to generating each of the magnetic fields, and corrects the magnetic vector of each of the magnetic fields based on the magnetic vector value; The angle derivation means acquires the vector angle from the magnetic vector value of each of the magnetic fields after correction by the vector value acquisition means.

2. The position estimation device according to claim 1.

3. A position estimation device as described in any one of claims 1 or 2, characterized in that it further comprises an attitude estimation means for estimating the attitude of the magnetic sensor based on the magnetic vector value of any one of the magnetic fields detected by the magnetic sensor and a predetermined reference magnetic vector value that serves as a reference for the magnetic vector of each magnetic field at each position where each magnetic field is generated.

4. the magnetic field control means causes each of the plurality of magnetic field generation means to generate two types of magnetic fields having different magnetic field directions; the vector value acquisition means corrects one of the two types of magnetic vector values ​​based on a difference between the two types of magnetic vector values ​​of the two types of magnetic fields generated by each of the plurality of magnetic field generation means and detected by the magnetic sensors; The angle deriving means derives the vector angle based on the magnetic vector value corrected by the vector value acquiring means.

2. The position estimation device according to claim 1.

5. causing a plurality of magnetic field generating means arranged at different positions to generate magnetic fields one by one in sequence; Obtaining magnetic vector values ​​of the magnetic fields generated one by one in sequence, which are detected by a magnetic sensor; Deriving a vector angle, which is an angle between the magnetic vectors of the magnetic fields, based on the acquired magnetic vector values; a position of the magnetic sensor is estimated based on a comparison result between a predetermined reference vector angle serving as a reference for a vector angle formed by magnetic vectors of the magnetic fields at each position in a coordinate space where the magnetic fields are generated and the derived vector angle; Location estimation method.

6. A program executed by a computer, a process of causing a plurality of magnetic field generating means arranged at different positions to generate magnetic fields one by one in sequence; A process of acquiring magnetic vector values ​​of the magnetic fields generated one by one in sequence and detected by a magnetic sensor; A process of deriving a vector angle, which is an angle between the magnetic vectors of the magnetic fields, based on the acquired magnetic vector values; a process of estimating the position of the magnetic sensor based on a comparison result between a predetermined reference vector angle serving as a reference for a vector angle formed by magnetic vectors of the magnetic fields at each position in a coordinate space where the magnetic fields are generated and the derived vector angle; A program to make this happen.

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