Patent Application
20130130712
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-254455, filed on Nov. 21, 2011, the entire contents of which are incorporated herein by reference.
The embodiments discussed herein are related to a terminal apparatus and a method for identifying a position.
In application systems in which a plurality of terminal apparatuses operate in cooperation with one another, such as a conference system, some uses are being studied in which each terminal apparatus issues an instruction or provides data to a particular terminal apparatus while utilizing positional information of other terminal apparatuses. In such uses, as a method for identifying a position of a terminal apparatus, some methods have been proposed in which each terminal apparatus utilizes radio field intensity from a wireless access point whose position is known in advance or time differences in communication between the terminal apparatuses.
For example, a technique has been proposed in which absolute positional information regarding a terminal apparatus is obtained using a global positioning system (GPS) or the like and transmitted to a server. When the terminal apparatus does not include a GPS or the like, the absolute position may be calculated on the basis of a relative position to another terminal apparatus that includes a GPS and transmitted to the server. The relative positional relationship between the terminal apparatus and another terminal apparatus may be obtained using trilateration based on communication radio field intensity. A technique is known in which the absolute position of a terminal apparatus is identified on the basis of absolute positions, which are known in advance, of base stations, communication radio field intensity from each base station, and directivity information regarding radio receiver sensitivity relative to each direction of the terminal apparatus. However, when a terminal apparatus that does not include a GPS is used, it is difficult to use the above methods for identifying a position.
Therefore, a method has been proposed in which the absolute position of a terminal apparatus is calculated on the basis of positions, which are known in advance, of fixed base stations, communication radio field intensity from each fixed base station, and calibration data regarding known signal intensity relative to each direction of the terminal apparatus. A technique for accurately calculating a position (or an absolute position) of a moving terminal apparatus has also been proposed in which the absolute position of the terminal apparatus may be accurately calculated by calculating an absolute position of the terminal apparatus on the basis of positions, which are known in advance, of fixed base stations and communication radio field intensity from each fixed base station and then by correcting the calculated absolute position using a relative movement position obtained from a gyro sensor or an acceleration sensor or the like of the terminal apparatus. However, in these methods for identifying a position, a base station whose position is known in advance and that serves as a reference, another terminal apparatus, or the like is supposed to be provided when the terminal apparatus identifies its own position.
d12=(xa−x1)2+(ya−y1)2
d22=(xa−x2)2+(ya−y2)2
Coordinates of positions of a terminal apparatus T_B and a terminal apparatus T_C may be calculated in the same manner as when the coordinates of the position of the terminal apparatus T_A are calculated. Thus, the positions of the terminal apparatuses T_A, T_B, and T_C may be calculated.
Currently, a technique has also been proposed in which an ad hoc network is constructed using the terminal apparatus itself as an access point. However, when the terminal apparatus itself serves as an access point, there is no base station or the like whose position is known in advance and that serves as a reference. Therefore, it is difficult to identify the position of the terminal apparatus.
Japanese Laid-open Patent Publication No. 2009-17217, Japanese Laid-open Patent Publication No. 2010-78528, Japanese Laid-open Patent Publication No. 2005-176386, and Japanese Laid-open Patent Publication No. 2005-274364 disclose related techniques.
According to conventional methods for identifying a position, it is difficult to identify a position of a terminal apparatus unless there is a base station or the like whose position is known in advance and that serves as a reference.
According to an aspect of the present invention, provided is a terminal apparatus including a processor. The processor obtains first information relating to communication states between the terminal apparatus and two or more other terminal apparatuses and between the two or more other terminal apparatuses. The processor identifies using trilateration, based on the first information, first relative positional relationships between the terminal apparatus and the two or more other terminal apparatuses. The processor measures, based on second information detected by a sensor, a movement direction and a movement distance of the terminal apparatus when the terminal apparatus has moved. The processor identifies second relative positional relationships between the terminal apparatus and the two or more other terminal apparatuses after the movement of the terminal apparatus. The processor calculates a relative position and a relative direction of the terminal apparatus relative to the two or more other terminal apparatuses, based on the first relative positional relationships, the second relative positional relationships, and the movement distance and the movement direction of the terminal apparatus.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
A terminal apparatus according to an embodiment identifies relative positions of a plurality of terminal apparatuses when the plurality of terminal apparatuses perform ad hoc communication.
The terminal apparatus calculates relative positional relationships with other terminal apparatuses on the basis of communication states with the other terminal apparatuses and communication states between the other terminal apparatuses, and measures, when the terminal apparatus has moved, a movement direction and a movement distance thereof on the basis of detected information. The position and the direction of the terminal apparatus relative to the other terminal apparatuses are then calculated and identified on the basis of the relative positional relationships, the movement direction, and the movement distance.
Terminal apparatuses according to embodiments will be described hereinafter with reference to the drawings.
According to a first embodiment, the relative position and direction of each terminal apparatus is identified even when there is no base station or the like that serves as a reference for identifying the position of each terminal apparatus. More specifically, the radio field intensity states between terminal apparatuses are obtained and the relative positions of the terminal apparatuses are identified using trilateration. In addition, each terminal apparatus measures the movement direction and the movement distance thereof using a gyro sensor, a geomagnetic sensor, an acceleration sensor, or the like and combines the movement direction and the movement distance thereof with the relative positions identified in the above-described manner, in order to identify the directions of the terminal apparatuses. Thus, the relative positions, directions, and the like of the terminal apparatuses may be identified, and an application system that uses positional information may be realized in an environment in which the terminal apparatuses are collected ad hoc.
The terminal apparatus is, for example, a portable apparatus having a communication function, and may be configured by a mobile phone such as a smartphone or a computer such as a laptop or tablet personal computer (PC).
The CPU 111 realizes each function of the terminal apparatus 11 by executing a program stored in the ROM 112, for example. The RAM 113 stores various pieces of data including intermediate data regarding operations executed by the CPU 111. The wireless LAN device 114 may communicate with other terminal apparatuses 11 and the like through a wireless LAN (not illustrated) in this example. Needless to say, the transmission/reception unit may have a configuration that enables communication with other terminal apparatuses 11 through a wireless network other than the wireless LAN. The display device 115 includes, for example, a liquid crystal display (LCD), and displays various pieces of data such as a menu and a result of processing for a user. The input device 116 includes, for example, a keyboard, and is operated when the user inputs an instruction, data, or the like to the terminal apparatus 11. The acceleration sensor 117 that detects the acceleration of the terminal apparatus 11, the geomagnetic sensor 118 that detects the geomagnetism at the position of the terminal apparatus 11, and the gyro sensor 119 that detects the angular speed, the angle, and the like of the terminal apparatus 11 have respective known configurations. Alternatively, only either the acceleration sensor 117 or the gyro sensor 119 may be provided.
The radio field intensity state obtaining unit 31 monitors communication between the terminal apparatuses 11 and obtains radio field intensity states, that is, for example, received signal strength indicator (RSSI) values, between the terminal apparatuses 11. At this time, the radio field intensity states between the terminal apparatuses 11 obtained by the radio field intensity state obtaining unit 31 include not only the radio field intensity states between the terminal apparatus 11 that includes the radio field intensity state obtaining unit 31 and other terminal apparatuses 11 but also the radio field intensity states between the other terminal apparatuses 11. Therefore, in the example illustrated in
The relative position identification unit 32 calculates, using the terminal apparatus 11A as an origin, a distance d_AB between the terminal apparatuses 11A and 11B, a distance d_AC between the terminal apparatuses 11A and 11C, and a distance d_BC between the terminal apparatuses 11B and 11C on the basis of the RSSI values between the terminal apparatuses 11, and identifies the coordinates of the terminal apparatus 11B and the terminal apparatus 11C through calculation using trilateration. If the Y coordinate yb of the terminal apparatus 11B is assumed to be 0 as with the terminal apparatus 11A, the following simultaneous equations may be solved.
d
—
AB
2=(xb)2+(yb=0)2
d
—
AC
2=(xc)2+(yc)2
d
—
BC
2=(xb−xc)2+(yc)2
Thus, the relative positions (0, 0), (xb, 0), and (xc, yc) of the terminal apparatus 11A, the terminal apparatus 11B, and the terminal apparatus 11C, respectively, may be calculated, and accordingly a relative position RPA of the terminal apparatus 11A relative to the terminal apparatus 11B and the terminal apparatus 11C may be obtained. However, at this time, since the position RPA of the terminal apparatus 11A relative to the terminal apparatus 11B and the terminal apparatus 11C is known, the positional relationships of the terminal apparatus 11A with the terminal apparatuses 11B and 11C are known, but the directions of the terminal apparatuses 11B and 11C from the terminal apparatus 11A are not clear.
When the terminal apparatus 11A has moved from a position indicated by a broken line in
The relative direction identification unit 34 communicates with the terminal apparatus 11B and the terminal apparatus 11C from the terminal apparatus 11A after the movement, and obtains the RSSI values after the movement between the terminal apparatus 11A and both the terminal apparatus 11B and the terminal apparatus 11C, in order to calculate new distances d_AB′ and d_AC′ between the terminal apparatuses 11A and 11B and between the terminal apparatuses 11A and 11C, respectively. In addition, the relative direction identification unit 34 may obtain a position RPS of the terminal apparatus 11A after the movement relative to the terminal apparatus 11B and the terminal apparatus 11C. Therefore, it is possible to obtain the relative directions of the terminal apparatuses 11B and 11C from the terminal apparatus 11A. If the distance between the terminal apparatuses 11A and 11B becomes smaller after the movement of the terminal apparatus 11A, it indicates that the terminal apparatus 11B exists in a direction in which the terminal apparatus 11A has moved, and the direction of the terminal apparatus 11C may also be identified on the basis of the direction of the terminal apparatus 11B. More specifically, a new position (xa, ya) of the terminal apparatus 11A in the original relative coordinate system may be calculated using the following simultaneous equations.
d
—
AB′
2=(xa−xb)2+(ya−yb=0)2
d
—
AC′
2=(xa−xc)2+(ya−yc)2
On the basis of the coordinate transformation (rotation) between the coordinates (Xa, Ya) and the coordinates (xa, ya), the rotational angle between the coordinates viewed from the gyro sensor 119 or the geomagnetic sensor 118 and the relative coordinate obtained in the relative position identification unit 32 are calculated, and finally the positions and the directions of the terminal apparatus 11B and the terminal apparatus 11C relative to the terminal apparatus 11A are obtained.
Thus, each terminal apparatus 11 communicates with other terminal apparatuses 11 and obtains RSSI values in relation to the other terminal apparatuses 11 using the radio field intensity state obtaining unit 31. On the basis of the RSSI values at this time, relative positions of the terminal apparatuses 11 after movement are identified through calculation by the relative position identification unit 32. The relative positions and directions of the terminal apparatuses 11 may be identified on the basis of the relative positions of the terminal apparatuses 11 identified by the relative position identification unit 32, the changes in the relative positions of the terminal apparatuses 11 identified by the relative direction identification unit 34, and the movement directions measured by the movement direction & distance measuring unit 33. Therefore, even when there is no base station or the like that serves as a reference for identifying the positions of the terminal apparatuses 11, the relative positions and directions of the terminal apparatuses 11 may be automatically identified.
In S1, the radio field intensity state obtaining unit 31, for example, determines whether or not there are two or more other terminal apparatuses around the terminal apparatus 11A. Whether there are two or more other terminal apparatuses around the terminal apparatus 11A may be determined using a known method such as, for example, counting identification information transmitted from terminal apparatuses capable of communicating with the terminal apparatus 11A. When a result of the determination in S1 is NO, the processing proceeds to S13, which will be described later. When the terminal apparatuses 11B and 11C are present around the terminal apparatus 11A, the result of the determination in S1 is YES, and the processing proceeds to S2.
In S2, the radio field intensity state obtaining unit 31 obtains the RSSI values between the terminal apparatus 11A and both the other terminal apparatuses 11B and 11C and the RSSI value between the other terminal apparatuses 11B and 11C, and stores the RSSI values in, for example, the RAM 113.
In S3, the radio field intensity state obtaining unit 31 determines whether or not there is another terminal apparatus. When a result of the determination in S3 is YES, the processing returns to S2. When the result of the determination in S3 is NO, the processing proceeds to S4.
In S4, the radio field intensity state obtaining unit 31 generates a table of the RSSI values and stores the table in, for example, the RAM 113.
In S5, the relative position identification unit 32 identifies a relative position RPA of the terminal apparatus 11A relative to the terminal apparatuses 11B and 11C through calculation using trilateration, and stores the relative position RPA in, for example, the RAM 113.
In S6, the movement direction & distance measuring unit 33 determines whether or not the terminal apparatus 11A has moved. When a result of the determination is NO, the processing returns to S6. When the result of the determination in S6 is YES, the processing proceeds to S7.
In S7, the movement direction & distance measuring unit 33 measures the movement distance and the movement direction of the terminal apparatus 11A, and stores resulting movement information MIB in, for example, the RAM 113.
In S8, the radio field intensity state obtaining unit 31 obtains the RSSI values between the terminal apparatus 11A and both the terminal apparatuses 11B and 11C and the RSSI value between the other terminal apparatuses 11B and 11C, and stores the RSSI values in, for example, the RAM 113.
In S9, the radio field intensity state obtaining unit 31 determines whether or not there is another terminal apparatus. When a result of the determination in S9 is YES, the processing returns to S8. When the result of the determination in S9 is NO, the processing proceeds to S10.
In S10, the radio field intensity state obtaining unit 31 generates a table of the RSSI values.
In S11, the relative position identification unit 32 identifies a relative position RPC of the terminal apparatus 11A after the movement relative to the terminal apparatuses 11B and 11C through calculation using trilateration, and stores the relative position RPC in, for example, the RAM 113.
In S12, the relative direction identification unit 34 identifies the relative position and the relative direction of the terminal apparatus 11A relative to the terminal apparatuses 11B and 11C through calculation on the basis of the relative position RPA, the movement information MIB, and the relative position RPC stored in the RAM 113, and stores the relative position and the relative direction in, for example, the RAM 113.
In S13, the relative direction identification unit 34, for example, reads the relative position and the relative direction of the terminal apparatus 11A relative to the other terminal apparatuses 11B and 11C from the RAM 113, and causes the display device 115 of the terminal apparatus 11A to display the relative position and the relative direction. The processing then ends.
Next, a second embodiment will be described with reference to
In S21, the terminal apparatus 11A communicates with the other terminal apparatuses 11B and 11C, and stores the movement directions and the movement distances of the other terminal apparatuses 11B and 11C, which have been measured by the respective movement direction & distance measuring units 33 in, for example, the RAM 113.
Since the terminal apparatuses 11A, 11B, and 11C each include the gyro sensor 119 or the geomagnetic sensor 118 and the acceleration sensor 117, even if the terminal apparatuses 11B and 11C other than the terminal apparatus 11A move, the movement distances and the movement directions of the other terminal apparatuses 11B and 11C may be transmitted to the terminal apparatus 11A when the terminal apparatus 11A and the other terminal apparatuses 11B and 11C communicate with each other to obtain the respective RSSI values. Therefore, after the relative position identification unit 32 identified the relative positions of the terminal apparatuses 11A, 11B, and 11C, the respective movement direction & distance measuring units 33 measure the movement distances and the movement directions of the terminal apparatuses 11A, 11B, and 11C, the relative position identification unit 32 identify again the relative positions of the terminal apparatuses 11A, 11B, and 11C, and then the relative positions and the relative directions of the terminal apparatuses 11A, 11B, and 11C may be identified on the basis of changes in the relative positions of the terminal apparatuses 11A, 11B, and 11C measured by the relative direction identification unit 34 and movement directions of the terminal apparatuses 11A, 11B, and 11C measured by the respective movement direction & distance measuring unit 33. That is, by executing the processing using the radio field intensity state obtaining unit 31, the relative position identification unit 32, the movement direction & distance measuring unit 33, the radio field intensity state obtaining unit 31, the relative position identification unit 32, and the relative direction identification unit 34 in this order, the relative positions and the relative directions of the terminal apparatuses 11A, 11B, and 11C may be identified.
As described above, according to the terminal apparatus and the method for identifying a position, the relative positions and the relative directions of a plurality of terminal apparatuses may be identified even if there is no base station that serves as a reference (that is, a reference for measuring a position) for identifying the positions of the terminal apparatus.
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-254455 | Nov 2011 | JP | national |
