JP2009042045A - Information terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information terminal capable of calculating and keeping a high-degree positional precision, even under such the condition that keeping the positional precision is normally difficult. <P>SOLUTION: The information terminal which has an acquisition means for acquiring positional information and reliability information, comprises an other terminal information acquiring means for communicating with another information terminal which has an acquisition means for acquiring positional information and reliability information, and acquiring or swapping the positional information and the reliability information of the another information terminal; and a calculating means for calculating new positional information and new reliability information by using the positional information and the reliability information which are acquired by the other terminal information acquiring means, and the positional information and the reliability information which are acquired by the acquisition means. The calculated positional information and reliability information are updated at each timing of communicating with the another information terminal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an information terminal that updates position information by acquiring position information, position accuracy information, and the like, and position information, position accuracy information, and the like of another information terminal.

  In recent years, there is an increasing demand for small terminals used for crime prevention and emergency response and GPS information terminals having a positioning function. The reason for such increased demand is that, for example, children and elderly people have small information terminals or GPS-equipped information terminals (cell phones with GPS functions), and parents and their families in the event of an emergency have their whereabouts. The provision of services that can instantly grasp the situation has been enhanced.

  In addition, when an emergency call (110, 119, or 118) is sent from a mobile phone, information on the place where the call is sent is automatically sent to the emergency call agency to which the call is connected. The introduction of “location notification system” has also started.

  Thus, the location information of the caller has become important information related to human life.

  Conventionally, as a method for obtaining location information of a mobile phone itself in a mobile phone, there is a method of obtaining location information (such as a distance between the base station and the mobile phone) from a base station to which the mobile phone is connected.

  However, the position information of the base station is calculated by a method using the position of the base station itself, and the position accuracy is determined by the arrangement density of the base stations, and it is difficult to expect high position accuracy.

  Therefore, as a method of solving such a problem, there is a method of accurately determining the position of the mobile phone itself by acquiring position information transmitted from GPS satellites orbiting the orbit and assist information from the base station.

  In addition, in the technique disclosed in Patent Document 1 below, the position information transmitted from the GPS satellite is used, and a plurality of mobile devices with GPS functions (cell phones with GPS functions) are used to transmit the GPS satellites. Position information and two other mobile devices among other mobile devices are selected, the distance between each mobile and GPS satellite is measured, and the measured values are exchanged to calculate the absolute position of the mobile device itself How to do is shown.

According to these methods, the position of the terminal can be determined with high accuracy based on the positioning information transmitted from the GPS satellite.
JP 2005-535908 Gazette

  However, in the technique disclosed in Patent Document 1 above, the distance between each information terminal and the satellite is measured, and the measured value is exchanged to calculate a highly accurate position. It is a premise that the distance measuring function is provided, and cannot be applied to an information terminal that does not have a GPS function.

  In addition, in the method of acquiring the positioning information from the GPS satellite and determining the position of the information terminal, it is possible to obtain highly accurate position information where the reception state of the satellite signal is good, but the positioning accuracy is remarkably indoors. In some cases, the accuracy is lower than the position information obtained from the base station.

  Furthermore, GPS receivers capable of positioning independently without obtaining assist information from the base station need to extract GPS satellite orbit information, ionosphere information, etc. from satellite signals. There is a problem that the measurement time is long and the measurement time is long.

  Therefore, the present invention has been made in view of such circumstances, and the position of another information terminal is difficult even under environmental conditions where it is difficult to maintain high position accuracy independently with the movement of the information terminal. By acquiring information and performing position calculation, it is intended to provide an information terminal that calculates and maintains position information with higher accuracy.

  The information terminal and the position calculation method according to the present invention have the following features in order to achieve the above-described object.

  An information terminal according to the present invention is an information terminal provided with position information generating means for generating position information and reliability information of the position information, and communicates with other information terminals, and the position information of the information terminal and the position information From other terminal information acquisition means for acquiring or exchanging reliability information of information, position information and reliability information generated by the position information generation means, and position information and reliability information acquired by the other terminal information acquisition means, New position information and position information calculating means for calculating reliability information, and the position information calculating means updates the position information and reliability information each time it communicates with a different information terminal. Features.

  The information terminal according to the present invention further includes communication means for communicating with the other information terminal and detecting a distance from the other information terminal, wherein the information terminal and the other information terminal are When entering the communicable range of the communication means, the communication means detects the distance between the terminals, the position information calculation means, the position information and reliability information generated by the position information generation means, New position information and reliability information are calculated from the position information and reliability information acquired by the other terminal information acquisition means and the inter-terminal distance detected by the communication means.

  The information terminal according to the present invention further includes short-range communication means capable of communicating with the other information terminal only at a short distance, and the information terminal and the other information terminal are connected to the communication means. When entering the communicable range, the short-range communication means approximates the distance between the terminals to zero, and based on the result that the distance between the terminals is zero, the position information calculation means The new position information and reliability information are calculated from the position information and reliability information generated by the information generation means and the position information and reliability information acquired by the other terminal information acquisition means. Information terminal described in 1.

  Moreover, in the information terminal according to the present invention, the communication unit measures the distance by a short-range wireless communication unit including a UWB system.

  In the information terminal according to the present invention, the communication unit measures the distance using an optical communication unit.

  Further, in the information terminal according to the present invention, the position information generating means works in conjunction with a system including a mobile phone communication network, and performs position calculation by using positioning information provided via a base station. And the reliability information is generated, or information necessary for the measured positioning calculation is given to the entity in the base station or the cellular phone communication network, and the positioning calculation is performed in the entity in the base station or the cellular phone communication network. And obtaining position information and reliability information.

  In addition, the information terminal according to the present invention communicates with other information terminals provided with position information generation means for generating position information and reliability information of the position information, and receives the position information and reliability information of the position information. Other terminal information acquisition means to acquire or exchange, storage means for holding predetermined position information and reliability information as initial values in advance, the position information and reliability information held in the storage means, Position information calculation means for calculating new position information and reliability information using the position information and the reliability information acquired from the other terminal information acquisition means, the position information calculation means further comprising: The position information and reliability information of the storage means are updated each time communication is performed with a different information terminal.

  In the information terminal according to the present invention, the updated reliability information is controlled such that the reliability decreases with the passage of time.

  In the information terminal according to the present invention, the information terminal is a mobile phone including a PHS that uses location information of a base station.

  In the information terminal according to the present invention, the position information generating means for generating the position information and the reliability information of the position information uses a GPS system.

  In the information terminal according to the present invention, the information terminal is a car navigation system.

  In the information terminal according to the present invention, the information terminal is a wireless LAN terminal using location information of an access point.

  The information terminal according to the present invention is characterized in that the information terminal sets an initial value of the position information to an arbitrary value.

  In the information terminal according to the present invention, the information terminal sets an initial value of reliability information to zero.

  Since the information terminal and the position calculation method according to the present invention have the above-described configuration, the following excellent effects can be obtained.

  That is, according to the information terminal according to the present invention, even in an environment where it is difficult to maintain high accuracy by itself, high-accuracy position information is obtained by exchanging position information of a plurality of terminals and performing position calculation. Can be acquired and maintain its accuracy.

  Further, according to the information terminal according to the present invention, the position information is exchanged between the information terminals by using the position information and the reliability information obtained through other communication networks without being limited to the GPS terminal, Position information can be calculated.

Embodiments of an information terminal according to the present invention will be described below with reference to the drawings.
1-7 is an example of embodiment of this invention, Comprising: The part which attached | subjected the same code | symbol in the figure represents the same thing.

FIG. 1 is a system outline diagram illustrating an embodiment of the present invention.
First, the basic concept of the entire system related to the information terminal according to the first embodiment (hereinafter described as a mobile phone terminal that is a representative example of the information terminal) will be described with reference to FIG.

  As shown in FIG. 1, the mobile phone terminal 20 has a GPS reception function for receiving a GPS information signal transmitted from a GPS satellite 30, captures the GPS information signal, and receives position information (coordinates (latitude, longitude). ) And reliability information (positioning accuracy) related to the position information. Similarly, the terminals 21, 22, and 23 are in a state of acquiring the respective position information and reliability information related to the position information. Each position information and reliability information is updated by tracking.

  When capturing this GPS information signal, for example, there is a method called Assisted GPS that can receive an assist information signal from the mobile phone base station 40 and capture the GPS signal at high speed using the received assist information. Commonly used.

  In general, a positioning-only GPS receiver that does not have a telephone function or the like receives assist information such as GPS satellite orbit information and ionosphere information from a GPS satellite signal and uses it for positioning. In addition, it takes time to receive information. In contrast, Assisted GPS can receive assist information using a mobile phone communication network, and therefore can perform positioning at high speed.

  By the way, when the user A holding the mobile phone terminal 20 moves under the above situation, the signal reception state of the mobile phone terminal 20 changes according to the reception environment condition. For example, outside of a building, satellite signals can be captured in a good reception state, but when entering indoors, as described above, the positioning accuracy is significantly reduced, and the position information obtained from the base station In some cases, the above accuracy cannot be obtained.

  Even when the positioning accuracy is remarkably deteriorated, if the positioning can be continued to some extent by tracking, it is possible to continue the tracking and update the position information. However, even if the position information can be updated, since the positioning accuracy is low, it may be impossible to obtain more accurate position information, or tracking may be impossible.

  Therefore, as shown in the figure, using the location information obtained by other mobile phone terminals 20, 21, 22, etc., to some extent improve the reduced positioning accuracy of the mobile phone terminal 20, maintain this, Consider providing more accurate location information.

  As described above, in addition to the position information obtained from the GPS information signal, etc., the cellular phone terminal can determine how reliable the obtained coordinates are with respect to the true coordinates in the position positioning system composed of GPS satellites and base stations. Reliability information θ indicating whether the degree (positioning accuracy) is provided is provided.

  Here, for example, the basic concept of calculating the accurate position information of the mobile phone terminal 20 by exchanging information with the mobile phone terminal 21 is as follows.

  That is, an accurate distance between the mobile phone terminal 20 and the mobile phone terminal 21 is measured, and an average component is calculated according to the reliability of the difference amount between the position information of each terminal and the above distance. By adding to the currently acquired position information of the mobile terminal 20, more accurate position information can be obtained.

  Furthermore, it can be expanded and applied to a plurality of mobile phone terminals gathered via different paths in which different location information is stored, and by averaging the plurality of location information according to the reliability, more accuracy can be obtained. High position information can be obtained.

  On the other hand, the reliability θ is also obtained by adding the reliability of each terminal, storing it together with the position information, and then communicating with a new terminal to update the position information. For example, if the stored reliability information is smaller, based on the currently obtained position information instead of the stored position information. It is also possible to calculate (details will be described later).

  In the above, the accuracy improvement of the position information and reliability information of the mobile phone terminal 20 has been described. Of course, the other mobile phone terminals 21, 22, 23 and the like have the same configuration as the mobile phone terminal 20. In this case, since it is possible to acquire the position information and reliability information of the mobile phone terminal 20, the accuracy of the position information and reliability information of each terminal itself can be obtained using these information. Can be high.

<Description of First Embodiment>
Next, the first embodiment will be described below with reference to FIGS. 2 and 3.
FIG. 2 is a diagram showing a system configuration example for explaining the first embodiment of the information terminal according to the present invention, and FIG. 3 is a flowchart showing the operation of the information terminal according to the present invention.

  FIG. 2 shows an example of a system configuration using a mobile phone terminal (hereinafter abbreviated as “terminal”) 20 and a terminal 21, but clearly shows a case where the terminal 20 and the terminal 21 are separated by a distance R. Since it is almost the same as the configuration shown in FIG. 1, the description of the system configuration is omitted.

Below, based on the operation | movement flowchart of FIG. 3, the detailed operation | movement of the terminal 20 is demonstrated.
In addition, since the terminal 21 operates in cooperation with the operation of the terminal 20, it will be described together.

First, acquisition means (GPS positioning function) such as position information of each terminal 20 and 21 acquires assist information from the mobile phone base station 40, performs GPS positioning, and acquires position information ( Coordinates) P _A and P _B and reliability information (positioning accuracy) θ _A and θ _B are held, and the position information and reliability information are updated by tracking.

In this state, when the terminal 20 enters an environment region in which it is difficult for the GPS signal to be received, the reliability information θ _A becomes low and is reflected in the position information P _A , so a search for another terminal is started. (Step S100).

  The terminal 20 (other terminal information acquisition means) confirms that the terminal 21 has entered the range 50 within a certain distance, and determines whether or not the presence of another terminal can be detected (step S110). At this time, the terminal 21 is also searching for another terminal (step S200). If no other terminal is detected (step S110; No), the process returns to step S110. When the terminal 21 is detected (step S110; Yes), communication between the terminals 20 and 21 is established (step S120, step S210), and mutual position information and reliability information are exchanged (step S130, step S220). . Alternatively, only the terminal 20 may acquire the position information and reliability information of the terminal 21.

  Further, the distance R between the terminals is measured (detecting means) (step S140, step S230). If a short-range wireless communication system such as UWB (Ultra Wide Band) is used as the distance measurement means, for example, distance measurement can be performed simultaneously while performing communication.

このように、信頼度情報θ_Ａが低下した場合であっても、２つの端末の情報から位置情報、信頼度情報とも精度を高めるとともに、これらの値を維持していくことが可能である。 Next, the position information calculation means calculates new position information P ′ _A , P ′ _B and reliability from the position information P _A , P _B and the reliability information θ _A , θ _B and the distance R, as shown in the following equation. The degree information θ ′ _A and θ ′ _B is calculated, and the position information and the reliability information are updated (steps S150 and S240).

As described above, even when the reliability information θ _A is lowered, it is possible to improve the accuracy of both the position information and the reliability information from the information of the two terminals and maintain these values.

  Here, if both the terminal 20 and the terminal 21 maintain a certain degree of accuracy while the reliability information currently acquired is lowered, the process returns to step S100 to find a new terminal. Up to this point, the above formula itself may be calculated based on the currently acquired position information, reliability information, and distance R, and tracking may be continued.

Further, when only the terminal 20 cannot obtain the position information P _A and the reliability information θ _A at all, P ′ _A calculated by the above equation 1 is changed to P _A of the equation 1, θ ′ by substituting _a in theta _a of formula 3, the expression 1 is calculated and may be continue tracking, even in a state can not be obtained at all information, while maintaining the accuracy of the reliability information It is possible to track.

  Furthermore, when no information is obtained at both the terminal 20 and the terminal 21, the current value is fixed, and the search process is continued until another new terminal is found.

  By the way, the information exchanged between the terminal 20 and the terminal 21 is position information and reliability information thereof, and is not GPS satellite information. That is, the terminals 20 and 21 do not necessarily have a GPS positioning function, and may have position information and reliability information corresponding thereto. For example, the terminal 21 may be a GPS mobile phone terminal, and the terminal 20 may be a PHS terminal using base station information.

  The terminals 20 and 21 may be a car navigation system mounted on a car instead of a GPS mobile phone. Further, a distance measuring device using a laser (light wave) mounted on a car may be used as a distance detecting means for the distance between terminals, and exchange of information such as position information is realized by using a communication function of a communication line network. May be.

  Further, the exchange of position information does not necessarily have to be performed using a short-range wireless communication method, and a mobile phone communication network may be used.

<Description of Example 1>
Next, an additional example 1 in the first embodiment will be described (see FIG. 2).
In the above description, the case where the terminal 20 and the terminal 21 are provided with a short-distance ranging function has been described. Even if it is not, the accuracy of the position information and the reliability information can be improved by exchanging the position information and the reliability information.

この実施例においても、位置情報と信頼度情報の更新の方法は、上記で説明したものと同じであるが、端末２１が数ｍの範囲から外れた場合には、急速に、位置情報及び信頼度の精度は元の精度戻ることになるが、範囲内に入っている限り、端末２０の位置情報及び信頼度情報の精度が向上し、維持される。 Both position information and reliability information are calculated by approximating the distance R between terminals of the above expressions 1 and 2 with 0 as in the following expressions 4 and 5, and calculating new position information P ′ _A and reliability information θ ′ _A. To do.

Also in this embodiment, the method for updating the position information and the reliability information is the same as that described above. However, when the terminal 21 is out of the range of several meters, the position information and the reliability information are rapidly changed. The accuracy of the degree returns to the original accuracy, but as long as it is within the range, the accuracy of the position information and reliability information of the terminal 20 is improved and maintained.

  In addition, although the distance between terminals was approximated by 0, you may use the fixed value corresponding to the detection range of a terminal.

<Description of Example 2>
Next, an additional example 2 in the first embodiment will be described (see FIG. 4).
FIG. 4 is a system configuration diagram showing another example of the information terminal according to the first embodiment of the present invention.

  Here, in contrast to the configuration using the two terminals 20 and 21 described with reference to FIG. 2, the present embodiment is expanded to three cases of GPS mobile phone terminals (hereinafter abbreviated as terminals) 70, 71 and 72. An example of the configuration will be described.

First, each of the terminals 70, 71, 72 performs GPS positioning from the mobile phone base station acquires assisting information, position information _P A obtained by the GPS _positioning, P B, _{P C} and the reliability information theta _A, They have θ _B and θ _C and are in a state where the position information is updated by tracking.

以上のように、２つの端末間の情報交換よりも、３つの端末間の情報交換を行えば、より位置情報、信頼度情報の精度が向上することが期待できる。 Here, when the terminals 70, 71, 72 are within a certain distance range, the distance information RAB, RBC, RAC with the counterpart terminal is measured simultaneously with exchanging position information and reliability information with each other. Similarly to the above, if a short-range wireless communication method such as UWB is used, it is possible to measure the distance while performing communication. From the respective position information, reliability information, and distance between terminals, new position information and reliability information are calculated as in the following formulas 6, 7, 8, and 9.

As described above, it can be expected that the accuracy of the position information and the reliability information is improved by exchanging information between the three terminals rather than exchanging information between the two terminals.

  Note that the processing including the update processing of position information and the like until a new terminal newly calculated by the above formulas 6, 7, 8, and 9 is found is the same as in the first embodiment.

<Description of Example 3>
Next, an additional example 3 in the first embodiment will be described (see FIG. 4).
FIG. 5 is a system configuration diagram showing another example of the information terminal according to the first embodiment of the present invention.

  In the second embodiment, the case where the three terminals 70, 71, and 72 are separated from each other has been described. However, in this embodiment, the number of terminals is further expanded to three or more, and the distance between the terminals is, for example, several meters. The case where it is within the range will be described.

Each terminal acquires assist information from the mobile phone base station, performs GPS positioning, and positional information P _A , P _B , P _C ,... Obtained by GPS positioning and reliability information θ _A , θ _B , The situation where θ _C ... is maintained and the position information is updated by tracking is the same as in the above embodiment.

Here, when each terminal 70, 71, 72,... Is in a range of, for example, several meters, if the target terminal is, for example, the terminal 70, the terminal 70 includes the position information of each terminal. Get reliability information. At this time, of these terminals, two terminals with high reliability information are selected. These two terminals For example, when the terminal 70 and the terminal 72 is a terminal itself of the subject, and acquires the position information P _A, P _C and the reliability information theta _A, a theta _C.

Here, assuming that P ₁ = P _A , P ₂ = P _C , θ ₁ = θ _A , θ ₂ = θ _C , new location information and reliability information are calculated according to the following equations 10 and 11, and each terminal is calculated. Distribute the calculation results.

このように、信頼度情報の高い２つの端末を選択することで、信頼度情報にバラツキの度合いが大きい（分散値が大）場合に、全ての情報を使用すると、却って信頼度を下げる結果となる場合があり、これを防止することが可能である。 In addition, first, position information and reliability information may be exchanged between the terminals, and two terminals with high reliability information may be selected for each terminal, and calculations of the following equations 10 and 11 may be performed.

In this way, by selecting two terminals with high reliability information, when the degree of variation in reliability information is large (the variance value is large), using all information results in a decrease in reliability. This can be prevented.

<Description of Example 4>
Next, an additional example 4 according to the first embodiment will be described (see FIG. 5).
In the present embodiment, as in the third embodiment, a plurality of terminals are within a range of several meters, and each terminal acquires assist information from a mobile phone base station and performs GPS positioning, It has position information P _A , P _B , P _C ,... Obtained by GPS positioning and reliability information θ _A , θ _B , θ _C ..., And the position information is updated by tracking. is there.

このように、上記実施例３のように、端末数を２つに限定せず、しかも所定以上の信頼度情報を使用することで、信頼度情報による平均化の積分効果を高め、位置情報の信頼度を高めるようにすることが可能である。 At this time, the terminal 70 sets the threshold value θ _TH and selects only the terminal whose reliability information is higher than θ _TH . When the condition is satisfied terminal is found N pieces (N> 1), the position information _{P 1, P 2, ···,} P N, 1 reliability information _{θ, θ 2, θ 3 ···} θ N Then, new coordinates and accuracy are calculated as in the following formulas 12 and 13.

As described above, the number of terminals is not limited to two as in the third embodiment, and the reliability information of a predetermined level or more is used, so that the integration effect of averaging by the reliability information is enhanced, and the position information It is possible to increase the reliability.

<Description of Second Embodiment>
Next, a second embodiment will be described with reference to FIG.
FIG. 6 is a system configuration diagram showing a second embodiment of the information terminal according to the present invention.

  In FIG. 6, as in the case of the above-described embodiment, the terminal 73 is a GPS mobile phone terminal, but the information terminal 74 is assumed to be a fixed terminal instead of a mobile terminal.

Therefore, the terminal 73 has a positional information P _A and the reliability information theta _A obtained by the GPS positioning, and the position information by tracking the status of updating the reliability information, whereas, fixed terminal 74, It has position information P _B set in advance and reliability information θ _B corresponding to this position information. Generally, higher reliability is set than the reliability information of terminal 73 which is a GPS mobile phone terminal. Is done. In other words, the terminal 74 is a signpost.

  As described in the first embodiment, when the terminal 73 enters the fixed distance range 50 with respect to the fixed terminal 74, the position information and the reliability information are mutually exchanged and the distance R between the terminals is measured at the same time. To do. If a near field communication method such as UWB is used, distance measurement can be performed while performing communication.

  Further, when the terminal 73 does not have a short distance measuring means, a fixed value R0 or 0 corresponding to the communication radius may be set.

ここで、数式１と３との違いは、固定端末７４の位置情報Ｐ_Ｂは固定値であり、θ_Ｂも変動幅が小さく固定値に近い。また、θ_Ｂ＞＞θ_Ａの条件が成立した場合には、固定端末７４の位置情報Ｐ_Ｂから距離Ｒだけ離れた位置（方向を考慮した座標位置）を算出することで、端末７３の位置情報が決定される。 Under such circumstances, new position information and reliability information of the terminal 73 are calculated by the following expressions 14 and 15 as in the expressions 1 and 3.

Here, the difference between Formulas 1 and 3 is that the position information P _B of the fixed terminal 74 is a fixed value, and θ _B has a small fluctuation range and is close to the fixed value. If the condition of θ _B >> θ _A is satisfied, the position of the terminal 73 is calculated by calculating a position (coordinate position in consideration of the direction) that is separated from the position information P _B of the fixed terminal 74 by the distance R. Information is determined.

<Description of Third Embodiment>
Next, a third embodiment will be described with reference to FIG.
FIG. 7 is a system configuration diagram showing a third embodiment of the information terminal according to the present invention.

As shown in FIG. 7, a fixed terminal 75 and a terminal 76 are considered. Similarly to the above-described embodiment, the terminal 76 acquires assist information from the mobile phone base station, performs GPS positioning, and has position information P _B and reliability information θ _B obtained by GPS positioning, Assume that the location information is being updated.

On the other hand, the fixed terminal 76 is different from the second embodiment, no preset position information P _A is also the reliability information theta _A, 0, chromatic position information, the acquisition means reliability information Assuming something that is not. That is, it is not necessary to set position information with high reliability in advance as in the second embodiment. In other words, it is a bulletin board with nothing written on it.

  When the terminal 76 enters a range of, for example, several meters with respect to the fixed terminal 75, the position information and the reliability information are exchanged with each other. In this case, the distance between terminals is approximated by zero.

ここで、上記数式１６、１８のαは、１以下の定数であり、固定端末７５の信頼度の変化を緩やかにするするためのものである。 From the position information and reliability information of both, new position information and reliability information are calculated as in the following equations 16, 17, 18, and 19.

Here, α in the above formulas 16 and 18 is a constant equal to or less than 1, and is intended to moderate the change in the reliability of the fixed terminal 75.

  Here, the method of updating the newly calculated position information has been briefly described in the first embodiment, but will be described in more detail.

In the initial state, although the fixed terminal 75 is zero without any reliability the position information, the position information of the first terminal 76 by the exchange of the reliability information, the newly calculated P _'A, next passing found terminal 76, when calculating the formula 16 again, the P _'a calculated by substituting the P _a, will be updated location information.

  Thus, while the reliability is low, the amount of information given from the fixed terminal 75 to the terminal 76 is small, but the location information of the fixed terminal 75 is updated by the location information given by many terminals 76, and the reliability is also high. It will become.

  As described above, the fixed terminal 75 obtains highly reliable position information by exchanging the position information with many terminals and updating it without setting the position information in the initial state. Further, the fixed terminal 75 itself does not need to have a positioning function, and it is possible to update its own position information using the position information of other terminals. According to Equation 18, the reliability information tends to increase every time the position is updated. However, an upper limit value can be set for the reliability information, or the reliability can be set to gradually decrease over time. It is.

  The operation example using the GPS mobile phone terminal has been described above. The feature of the present invention is that the position information and the reliability information are exchanged between a plurality of terminals located at a short distance by exchanging the position information and the reliability information. The target is not limited to the GPS mobile phone terminal.

  Further, the position information measurement method is not limited to the method using GPS.

  The information terminal of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

It is a system outline figure explaining a 1st embodiment. It is a figure which shows the system configuration example for demonstrating 1st Embodiment of the information terminal which concerns on this invention. It is a flowchart which shows operation | movement of the information terminal which concerns on this invention. It is a system block diagram which shows the other Example in 1st Embodiment of the information terminal which concerns on this invention. It is a system configuration | structure figure which shows the other Example in 1st Embodiment of the information terminal which concerns on this invention. It is a system configuration figure showing a 2nd embodiment of the information terminal concerning the present invention. It is a system block diagram which shows 3rd Embodiment of the information terminal which concerns on this invention.

Explanation of symbols

20, 21, 22, 23 Mobile phone terminal 30 GPS satellites 40, 41, 42 Mobile phone base station 50 Distance measurable area 70, 71, 72, 73, 76 Terminal 74, 75 Fixed terminal

Claims (14)

An information terminal comprising position information generating means for generating position information and reliability information of the position information,
Other terminal information acquisition means for communicating with other information terminals and acquiring or exchanging position information of the information terminal and reliability information of the position information;
Position information calculation means for calculating new position information and reliability information from the position information and reliability information generated by the position information generation means and the position information and reliability information acquired by the other terminal information acquisition means; With
The position information calculating means updates position information and reliability information each time it communicates with a different information terminal. Furthermore, the communication means for communicating with the other information terminal, and detecting a distance from the other information terminal,
When the information terminal and the other information terminal are within the communicable range of the communication means, the communication means detects the distance between the terminals, and the position information calculation means is the position information generation means. New position information and reliability information are calculated from the position information and reliability information generated by the above, the position information and reliability information acquired by the other terminal information acquisition means, and the inter-terminal distance detected by the communication means. The information terminal according to claim 1. Furthermore, a short-range communication means capable of communicating with the other information terminal only at a short distance,
When the information terminal and the other information terminal are within the communicable range of the communication means, the short-range communication means approximates the distance between the terminals to zero and sets the distance between the terminals to zero. On the basis of the result, the position information calculation means calculates new position information and reliability information from the position information and reliability information generated by the position information generation means and the position information and reliability information acquired by the other terminal information acquisition means. The information terminal according to claim 1, wherein reliability information is calculated.   The portable terminal according to claim 2, wherein the communication unit measures a distance by a short-range wireless communication unit including a UWB system.   The information terminal according to claim 2, wherein the communication unit measures a distance by an optical communication unit.   The position information generation means generates position information and reliability information by performing positioning calculation using assist information given through a base station in conjunction with a system including a mobile phone communication network, or The information necessary for the measured positioning calculation is given to the base station or the entity in the mobile phone communication network, and the position information and the reliability information calculated by the positioning in the base station or the entity in the mobile phone communication network are acquired. The information terminal according to any one of claims 1 to 5, wherein: Other terminal information acquisition means for communicating with other information terminals provided with position information generating means for generating position information and reliability information of the position information, and acquiring or exchanging the position information and reliability information of the position information ,
Storage means for holding predetermined position information and reliability information as initial values in advance;
New position information and reliability information are calculated using the position information, the reliability information, and the position information and the reliability information acquired from the other terminal information acquisition means held in the storage means. Position information calculation means,
The position information calculation means updates the position information and reliability information of the storage means every time it communicates with a different information terminal.   The information terminal according to claim 7, wherein the updated reliability information is controlled such that the reliability decreases with time.   The information terminal according to any one of claims 1 to 6, wherein the information terminal is a mobile phone including a PHS that uses position information of a base station.   The information according to any one of claims 1 to 6, wherein the position information generation unit that generates the position information and reliability information of the position information uses a GPS system. Terminal.   The information terminal according to claim 10, wherein the information terminal is a car navigation system.   The information terminal according to any one of claims 1 to 6, wherein the information terminal is a wireless LAN terminal that uses location information of an access point.   The information terminal according to claim 7 or 8, wherein the information terminal sets an initial value of the position information to an arbitrary value.   9. The information terminal according to claim 7, wherein the information terminal sets an initial value of reliability information to zero.

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