JP2008215924A - Positioning apparatus, positioning method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly measure a current position, even when a reception condition of a signal is faulty. <P>SOLUTION: A latitude in the current position is calculated from a detection result obtained by a geomagnetic detection section 50. Since the magnetic inclination of a geomagnetic vector is different according to the latitude, the latitude in the current position can be calculated by obtaining the magnetic inclination of the geomagnetic vector from the detection result obtained by the geomagnetic detection section 50. The current position is measured, based on a GPS satellite signal received from an acquired GPS satellite and the latitude calculated from the detection result obtained by the geomagnetic detection section 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positioning device, a positioning method, and a program.

  As a positioning system using an artificial satellite, a GPS (Global Positioning System) is widely known and is used in a car navigation device or the like. Recently, portable electronic devices such as portable telephones and wristwatches have been equipped with a GPS function, and improvement of positioning technology is desired.

In such a situation, in addition to satellite signals such as GPS, a technique for detecting the direction and using it for dead reckoning is disclosed in Patent Document 1. Specifically, this is a technique for detecting the current position by detecting the geomagnetism, detecting the traveling direction, integrating the moving distance and the amount of change in the direction, and performing map matching.
Japanese Patent No. 2865624

  However, since the technique of Patent Document 1 performs map matching after integrating the moving distance and the amount of change in direction, the positioning accuracy is naturally limited. In addition, as one of the biggest problems of the positioning method using satellite signals, there is a positioning problem when the reception status of the satellite signals is poor. For example, in a situation where the positioning device is located in a building, it is often impossible to acquire a sufficient number of satellites, and in this case, positioning cannot be performed.

  Also, in an urban canyon environment where high-rise buildings are adjacent, even if a sufficient number of satellites are successfully acquired and positioning is possible, there is a significant error in positioning results due to the effects of multipath. May occur.

  The present invention has been made in view of the above-described problems.

  According to a first aspect of the present invention, there is provided a receiving unit that receives a positioning signal transmitted from a positioning satellite, a geomagnetic detection unit that detects geomagnetism, and a current position based on a detection result by the geomagnetic detection unit. It is a positioning apparatus provided with a latitude calculating unit that calculates the latitude of the current position, and a positioning unit that measures the current position based on the positioning signal received by the receiving unit and the latitude calculated by the latitude calculating unit.

  According to a seventh aspect of the present invention, there is provided a positioning method of a current position using a geomagnetism detection unit that detects geomagnetism, a reception step of receiving a positioning signal transmitted from a positioning satellite, and detection by the geomagnetism detection unit A positioning method including a latitude calculating step for calculating the latitude of the current position from the result, and a positioning step for positioning the current position based on the positioning signal received in the receiving step and the latitude calculated in the latitude calculating step May be configured.

  According to the first aspect of the invention, the latitude of the current position is calculated from the geomagnetic detection result, and the current position is determined based on the positioning signal received from the positioning satellite and the calculated latitude. By using the latitude of the current position calculated from the detection result of geomagnetism as so-called assist information for positioning, the current position can be measured even when the reception status of the positioning signal is poor.

  Specifically, as a second invention, the geomagnetism detection unit in the positioning device of the first invention has a triaxial geomagnetic sensor and an acceleration sensor, and the absolute position at the current position regardless of the attitude of the own device. A geomagnetic vector may be detected, and the latitude calculating unit may be configured to calculate a latitude based on at least the dip angle of the geomagnetic vector detected by the geomagnetic detecting unit.

  Further, as an eighth invention, the geomagnetism detecting unit in the positioning method of the seventh invention has a triaxial geomagnetic sensor and an acceleration sensor, and an absolute geomagnetic vector at the current position is obtained regardless of the posture of the own device. The positioning method may be configured such that the latitude calculation step is a step of calculating the latitude based on at least the dip angle of the geomagnetic vector detected by the geomagnetism detection unit.

  According to the second aspect of the invention, the absolute geomagnetic vector at the current position is detected by the triaxial geomagnetic sensor and the acceleration sensor regardless of the posture of the device, and based on at least the dip angle of the detected geomagnetic vector. The latitude is calculated. The dip angle of the geomagnetic vector is distributed almost parallel to the latitude line. For this reason, by calculating the latitude based on at least the dip angle of the detected geomagnetic vector, the latitude of the current position can be obtained appropriately.

  Further, as a third invention, the positioning unit in the positioning device of the first or second invention is based on the positioning signal received by the receiving unit from the positioning satellite that has transmitted the positioning signal. Latitude information for detecting a pseudo distance calculating unit for calculating a pseudo distance and a reception status of a positioning signal by the receiving unit satisfying a predetermined condition as a reception status condition for performing positioning using latitude information A use positioning status detection unit, and a latitude information use positioning unit that performs a positioning calculation that specifies a current position from the pseudo distance calculated by the pseudo distance calculation unit and the latitude calculated by the latitude calculation unit at the time of detection. It is good also as comprising the positioning apparatus which has.

  Further, as a ninth invention, the positioning step in the positioning method of the seventh or eighth invention is based on the positioning signal received in the receiving step from the positioning satellite that has transmitted the positioning signal. A latitude for detecting a pseudo-distance calculating step for calculating a pseudo-distance, and for detecting that a reception status of a positioning signal in the receiving step satisfies a condition predetermined as a reception status for performing positioning using latitude information An information utilization positioning situation detection step, and a latitude information utilization positioning step for performing a positioning operation to identify a current position from the pseudo distance calculated in the pseudo distance calculation step and the latitude calculated in the latitude calculation step during the detection; You may comprise the positioning method containing.

  According to the third aspect of the invention, the pseudo distance from the positioning satellite that has transmitted the received positioning signal is calculated. Then, when it is detected that the reception status of the positioning signal satisfies a condition predetermined as a reception status for performing positioning using latitude information, the calculated pseudo-range and the geomagnetic detection result Positioning calculation is performed to identify the current position from the latitude calculated from.

  For example, by determining in advance that the number of positioning satellites that have received positioning signals is less than a predetermined number of positioning-possible satellites (for example, three) as a condition of reception conditions, a sufficient number of positioning satellites can be obtained. It is possible to measure the current position even in an environment where it cannot be captured.

  Further, as a fourth invention, the positioning unit in any one of the first to third inventions is based on the positioning signal received by the receiving unit, from the positioning satellite that has transmitted the positioning signal. A pseudo distance calculation unit that calculates a pseudo distance, a temporary positioning position calculation unit that calculates a temporary positioning position from the pseudo distance calculated by the pseudo distance calculation unit, and a temporary positioning calculated by the temporary positioning position calculation unit Determining a suitability between the latitude of the position and the latitude calculated by the latitude calculating unit, and configuring a positioning device having a current position determining unit that determines the provisional positioning position as the current position when it is determined to be appropriate It is good.

  Further, as a tenth invention, for the positioning in which the positioning step in the positioning method according to any of the seventh to ninth inventions transmits the positioning signal based on the positioning signal received in the receiving step. Calculated in a pseudo distance calculating step for calculating a pseudo distance from the satellite, a temporary positioning position calculating step for calculating a temporary positioning position from the pseudo distance calculated in the pseudo distance calculating step, and the temporary positioning position calculating step. A positioning method including a current position determining step of determining whether the latitude of the provisional positioning position and the latitude calculated in the latitude calculating step are appropriate and determining the provisional positioning position as the current position when it is determined to be appropriate It may be configured.

  According to the fourth aspect of the invention, the pseudo distance from the positioning satellite that has transmitted the received positioning signal is calculated, and the provisional positioning position is calculated from the pseudo distance. Then, it is determined whether the latitude of the calculated temporary positioning position and the latitude calculated from the geomagnetic detection result are appropriate. If it is determined to be appropriate, the temporary positioning position is determined as the current position.

  The latitude calculated from the detection result of geomagnetism indicates the latitude of the current position of the device. Therefore, when the latitude of the positioning position tentatively calculated deviates from the latitude calculated from the geomagnetic detection result, the provisional positioning position is likely to be an incorrect positioning result. Therefore, for example, it is possible to avoid adopting an incorrect positioning result by determining that the latitude of the provisional positioning position is appropriate when the latitude calculated from the geomagnetic detection result approximates or matches the latitude.

  Further, as a fifth invention, for the positioning in which the positioning unit in the positioning device according to any one of the first to third inventions transmits the positioning signal based on the positioning signal received by the receiving unit. Calculated by a pseudo distance calculation unit that calculates a pseudo distance from the satellite, a temporary positioning position calculation unit that calculates a temporary positioning position from the pseudo distance calculated by the pseudo distance calculation unit, and the temporary positioning position calculation unit. The temporary positioning position may be corrected based on the latitude calculated by the latitude calculating unit, and a current position correction calculating unit that calculates a current position may be configured.

  As an eleventh aspect of the invention, the positioning step in the positioning method according to any of the seventh to ninth aspects of the invention transmits the positioning signal based on the positioning signal received in the receiving step. Calculated in a pseudo distance calculating step for calculating a pseudo distance from the satellite, a temporary positioning position calculating step for calculating a temporary positioning position from the pseudo distance calculated in the pseudo distance calculating step, and the temporary positioning position calculating step. A positioning method including a current position correction calculating step of correcting the temporary positioning position based on the latitude calculated in the latitude calculating step and calculating a current position may be configured.

  According to the fifth aspect and the like, the pseudo distance from the positioning satellite that has transmitted the received positioning signal is calculated, and the provisional positioning position is calculated from the pseudo distance. Then, the calculated temporary positioning position is corrected based on the latitude calculated from the geomagnetic detection result, and the current position is calculated. Since the latitude calculated from the detection result of geomagnetism represents the latitude of the current position of the device itself, the current position can be appropriately obtained by correcting the temporary positioning position based on the latitude.

  Furthermore, as a sixth invention, the latitude calculated by the latitude calculation unit is calculated by the latitude calculation unit by the current position correction calculation unit in the positioning device of the fifth invention, the latitude of the provisional positioning position calculated by the provisional positioning position calculation unit. It is good also as comprising the positioning apparatus which correct | amends to and calculates a present position.

  According to a twelfth aspect of the present invention, in the positioning method of the eleventh aspect of the present invention, the current position correction calculating step calculates the latitude of the temporary positioning position calculated in the temporary positioning position calculating step by using the latitude calculated in the latitude calculating step. You may comprise the positioning method which is a step which correct | amends to and calculates a present position.

  According to the sixth aspect and the like, the latitude of the temporary positioning position is corrected to the latitude calculated from the geomagnetic detection result, and the current position is calculated.

  As a thirteenth invention, a program for causing a computer including a geomagnetism detection unit that detects geomagnetism to execute any one of the seventh to twelfth positioning methods may be configured. In this case, the same effect as the seventh to twelfth inventions is exhibited by reading and executing the program by the computer.

  A mobile phone 1 having a navigation function will be described below as an embodiment of a positioning device with reference to the drawings. However, embodiments to which the present invention can be applied are not limited to this.

1. Principle The mobile phone 1 receives a GPS satellite signal as a satellite signal transmitted (transmitted) from a GPS satellite that is a positioning satellite, and orbit information (ephemeris data) of the GPS satellite superimposed on the received GPS satellite signal. Satellite information such as the position, moving direction, and speed of the GPS satellites is calculated based on a navigation message such as (or almanac data).

  Note that four GPS satellites are arranged on each of the six orbital planes, and in principle, four or more satellites are operated from anywhere on the earth so that they can always be observed in a geometric arrangement. Hereinafter, a GPS satellite that has transmitted a received (captured) GPS satellite signal is referred to as a “capture satellite” in order to distinguish it from other GPS satellites.

  In addition, the mobile phone 1 automatically detects from the captured satellite based on the difference between the reception time of the GPS satellite signal specified by the built-in quartz clock and the transmission time of the received GPS satellite signal from the GPS satellite. Calculate the radio wave propagation time to the aircraft. Then, the distance (pseudo distance) from the captured satellite to the own aircraft is calculated by multiplying the calculated radio wave propagation time by the speed of light.

  The mobile phone 1 uses four parameter values, a three-dimensional coordinate value indicating the position of its own device and a clock error, as the satellite information of a plurality of captured satellites and the distance from each captured satellite to its own device (pseudo distance). ) And the like to determine the current position of the aircraft.

  Specifically, when the number of captured satellites is four or more, the convergence calculation using the successive approximation calculation method (Newton method) or the like is performed based on the satellite information and pseudorange calculated for each captured satellite. The convergence value is determined as a positioning position. This positioning method is generally known as three-dimensional positioning.

  When the number of captured satellites is 3, the number of satellites is insufficient, and positioning is performed assuming that the earth center is one satellite. Specifically, the positioning calculation is performed using information such as the distance from the earth center to the ground surface in addition to information such as the pseudo distance calculated for each captured satellite. This positioning method is generally known as two-dimensional positioning.

  Conventionally, when the number of captured satellites is two or less, it has been impossible in principle to perform positioning. However, for example, assuming a situation where the mobile phone 1 is located in a building, it is often difficult to capture even three GPS satellites, and positioning cannot be performed under such a situation. . In order to solve this problem, the present inventor has devised a completely new positioning method capable of positioning even when the number of captured satellites is two.

  FIG. 1 is a diagram for explaining the principle of positioning in this embodiment. FIG. 1A is a diagram for explaining the concept of pseudo distance, and FIG. 1B is a diagram for explaining the principle of position determination of the mobile phone 1. Here, a description will be given assuming that two GPS satellites G1 and G2 are captured.

  The mobile phone 1 is an intersection of a sphere S1 whose center is the position of the capture satellite G1 and whose radius is the pseudorange R1, and a sphere S2 whose center is the position of the capture satellite G2 and whose radius is the pseudorange R2. It should be located on the circle C1 (FIG. 1 (A)). The pseudo distances R1 and R2 are given by the following expressions (1) and (2), respectively.

但し、（ｘ_１，ｙ_１，ｚ_１）は捕捉衛星Ｇ１の位置座標、（ｘ_２，ｙ_２，ｚ_２）は捕捉衛星Ｇ２の位置座標、Ｒ_１は擬似距離Ｒ１、Ｒ_２は擬似距離Ｒ２、（ｘ，ｙ，ｚ）は携帯型電話機１の位置座標、「ｃ」は光速度、「Δｔ」はＧＰＳ衛星と携帯型電話機１との時計誤差をそれぞれ示している。

_{However, (x 1, y 1,} z 1) is the position coordinates of the captured satellite _{G1, (x 2, y 2} , z 2) is the position coordinates of the captured satellite G2, _{R 1} is pseudoranges R1, _{R 2} is pseudoranges R2, (x, y, z) are the position coordinates of the mobile phone 1, "c" is the speed of light, and "Δt" is the clock error between the GPS satellite and the mobile phone 1.

When it is assumed that the mobile phone 1 is located on the ground surface (altitude = 0), the position of the mobile phone 1 is regarded as an intersection of the circle C1 and the earth SE, regarding the earth SE as one satellite. It can be obtained (FIG. 1B). In this case, the distance R _E (= the radius of the earth) from the earth center O to the mobile phone 1 is given by the following expression (3).

但し、（ｘ_E，ｙ_E，ｚ_E）は、地球中心Ｏの位置座標を示しており、地球基準座標系で考えた場合は（ｘ_E，ｙ_E，ｚ_E）＝（０，０，０）である。

However, (x _E , y _E , z _E ) indicates the position coordinates of the earth center O, and (x _E , y _E , z _E ) = (0, 0, 0).

In the present embodiment, description will be made assuming that the positioning calculation is performed with the altitude of the mobile phone 1 set to “0”. However, when the altitude of the mobile phone 1 is known, the distance from the earth center O to the altitude is described. Positioning calculation may be performed with the distance _RE as the distance RE.

  The position of the mobile phone 1 can be obtained as the intersection of the circle C1 and the earth SE. However, since the circle C1 and the earth SE intersect at two points P1 and P2, which intersection is the position of the portable phone 1. I don't know if Therefore, the position of the mobile phone 1 is determined using geomagnetism.

FIG. 2 is a diagram for explaining geomagnetism. FIG. 2A is a diagram for explaining the concept of geomagnetism, and FIG. 2B is a diagram for explaining the elements of geomagnetism.
The earth can be thought of as a giant magnet with the north as the south pole and the south as the north pole, and a magnetic field is generated on the earth by the action of magnetic force (FIG. 2 (A)). This magnetic field is called geomagnetism, and can be expressed by a vector (hereinafter referred to as “geomagnetic vector”) having three elements of declination, dip and total magnetic force, starting from the current position (FIG. 2 ( B)).

  The declination is an inclination of geomagnetism with respect to true north in a horizontal plane, and can be expressed by an angle with a clockwise direction as positive, for example. The dip angle is the inclination of geomagnetism with respect to the horizontal plane, and can be expressed by an angle with the lower side of the horizontal plane being positive, for example. The total magnetic force is the magnitude of the geomagnetic vector, and corresponds to the strength of the magnetic field at the current position.

  The direction and the magnitude of the geomagnetic vector vary depending on the location. For example, in Japan, the declination and the dip angle increase toward the north (= high latitude). What is characteristic is that the dip angle of the geomagnetic vector is distributed substantially parallel to the latitude line. This means that the approximate latitude of the current position can be calculated from the dip angle of the geomagnetic vector.

  Therefore, in the present embodiment, an absolute geomagnetic vector at the current position is detected regardless of the attitude of the mobile phone 1 using a triaxial geomagnetic sensor and an acceleration sensor, and based on the detected depression angle of the geomagnetic vector. Calculate the latitude. Then, the current position of the mobile phone 1 is determined by rejecting an intersection having a large latitude difference from the latitude calculated based on the dip angle of the geomagnetic vector from the two intersections P1 and P2 between the circle C1 and the earth SE. To do.

  For example, in FIG. 1B, the intersection P1 of the two intersections P1 and P2 is located on the latitude line C2 connecting the latitudes calculated from the dip angle of the geomagnetic vector. Therefore, the intersection P1 indicates the position of the mobile phone 1.

  Note that the pseudo distance represented by the equations (1) and (2) includes the clock error Δt, but the influence of the clock error Δt is based on the specified accuracy of the quartz watch built in the mobile phone 1. Since the technique for compensating for the above or compensating for the influence of the clock error Δt by past positioning for a fixed time is a conventionally known technique, a detailed description thereof will be omitted.

2. Configuration FIG. 3 is a block diagram showing a functional configuration of the mobile phone 1. The mobile phone 1 includes a GPS antenna 5, a GPS receiver 10, a TCXO (Temperature Compensated Crystal Oscillator) 40, a geomagnetism detector 50, a host CPU 60, an operation unit 70, a display unit 80, and a mobile phone. An antenna 90, a mobile phone wireless communication circuit unit 100, a ROM (Read Only Memory) 110, and a RAM (Random Access Memory) 120 are provided.

  The GPS antenna 5 is an antenna that receives an RF signal including a GPS satellite signal transmitted (transmitted) from a GPS satellite that is a positioning satellite, and outputs the received signal to the GPS receiver 10. The GPS satellite signal is a spread spectrum modulated signal called a C / A (Coarse and Acquisition) code, and is superimposed on an L1 band carrier wave having a frequency of 1.57542 [GHz].

  The GPS receiving unit 10 is a positioning unit that measures the current position of the mobile phone 1 based on a signal output from the GPS antenna 5, and is a functional block corresponding to a so-called GPS receiver. The GPS receiving unit 10 includes an RF (Radio Frequency) receiving circuit unit 20 and a baseband processing circuit unit 30. The RF receiving circuit unit 20 and the baseband processing circuit unit 30 can be manufactured as separate LSIs (Large Scale Integration), or can be manufactured as one chip.

  The RF receiving circuit unit 20 is a circuit block of a high-frequency signal (RF signal), and generates an oscillation signal for RF signal multiplication by dividing or multiplying the oscillation signal generated by the TCXO 40. Then, by multiplying the generated oscillation signal by the RF signal output from the GPS antenna 5, the RF signal is down-converted to an intermediate frequency signal (hereinafter referred to as an "IF (Intermediate Frequency) signal"). After the IF signal is amplified, it is converted into a digital signal by an A / D converter and output to the baseband processing circuit unit 30.

  The baseband processing circuit unit 30 performs correlation processing on the IF signal output from the RF receiving circuit unit 20 to capture and extract GPS satellite signals, decodes the data, and extracts navigation messages, time information, etc. This is a circuit unit that performs pseudorange calculation, positioning calculation, and the like. The baseband processing circuit unit 30 includes a circuit that performs correlation processing, a circuit that generates a spreading code for correlation processing, a circuit that decodes data, and a CPU 31 that is a processor that comprehensively controls the GPS receiving unit 10, and a memory And a ROM 33 and a RAM 35.

  FIG. 4 is a diagram illustrating an example of data stored in the ROM 33. The ROM 33 stores a baseband processing program 331 that is read by the CPU 31 and executed as baseband processing (see FIG. 8), and latitude-specific geomagnetic data 333. Further, the baseband processing program 331 includes a geomagnetism-based two-dimensional positioning program 3311 executed as a geomagnetism-based two-dimensional positioning process (see FIG. 9) as a subroutine.

  The baseband process is a process in which the CPU 31 measures the current position of the mobile phone 1 while switching the positioning method based on the number of captured GPS satellites. The baseband process will be described later in detail using a flowchart.

  The geomagnetism-based two-dimensional positioning process is a process executed when the number of captured GPS satellites is two, and the CPU 31 performs a positioning process using the geomagnetism detection result by the geomagnetism detection unit 50. is there. The geomagnetism-based two-dimensional positioning process will be described later in detail using a flowchart.

  FIG. 6 is a diagram illustrating an example of the data configuration of the geomagnetic data 333 according to latitude. The latitude-based geomagnetic data 333 stores a latitude 3331 and an inclination angle 3333 of the geomagnetic vector in association with each other. In FIG. 6, in order to simplify the explanation, the measured values of the dip angle in increments of latitude “1 °” are stored, but it is required to store the dip angle for every second of latitude by the frequency method. More detailed data may be stored according to the positioning accuracy.

  FIG. 5 is a diagram illustrating an example of data stored in the RAM 35. The RAM 35 stores satellite data 351, geomagnetic sensor data 352, acceleration sensor data 353, geomagnetic vector data 354, geomagnetic calculation latitude data 355, provisional positioning position latitude data 356, and positioning data 357. .

  FIG. 7 is a diagram illustrating an example of the data configuration of the satellite data 351. In the satellite data 351, the satellite number 3511, the satellite position 3513, the satellite moving direction 3515, and the satellite speed 3517 are stored in association with each other as satellite information. The satellite position 3513 is represented by, for example, a three-dimensional coordinate value in the earth reference coordinate system, and the satellite movement direction 3515 is represented by, for example, a three-dimensional unit vector in the earth reference coordinate system. In the baseband processing, the CPU 31 extracts navigation messages and time information from the received GPS satellite signals, calculates satellite information of captured satellites based on these information, and stores them in the satellite data 351.

  The geomagnetic sensor data 352 stores the detection result of the geomagnetic sensor 51. The acceleration sensor data 353 stores the detection result of the acceleration sensor 53. In the two-dimensional positioning process using geomagnetism, the CPU 31 acquires the detection result from the geomagnetic sensor 51 and stores it in the geomagnetic sensor data 352, acquires the detection result from the acceleration sensor 53, and stores it in the acceleration sensor data 353.

  The geomagnetic vector data 354 stores information on declination, dip and total magnetic force as geomagnetic vectors. In the geomagnetism-based two-dimensional positioning process, the CPU 31 calculates a geomagnetic vector based on the detection result acquired from the geomagnetic sensor 51 and the detection result acquired from the acceleration sensor 53 and stores it in the geomagnetic vector data 354.

  Since the detection result of the geomagnetic sensor 51 changes relatively according to the attitude (tilt) of the mobile phone 1, the detection result of the geomagnetic sensor 51 alone indicates that the current position of the mobile phone 1 is in the earth coordinate system. The absolute geomagnetic vector cannot be determined accurately. Therefore, by detecting the acceleration in the direction of gravity by the acceleration sensor 53 and specifying the posture of the mobile phone 1, the absolute geomagnetic vector at the current position can be obtained regardless of the posture of the mobile phone 1.

  The geomagnetism calculated latitude data 355 stores the latitude calculated from the dip angle of the geomagnetic vector (hereinafter referred to as “geomagnetic calculated latitude”). In the geomagnetism-based two-dimensional positioning process, the CPU 31 refers to the latitude geomagnetic data 333 stored in the ROM 33, calculates (converts) the latitude 3331 from the calculated dip angle 3333 of the geomagnetic vector, and calculates the geomagnetic calculated latitude as the geomagnetic calculated latitude. The data 355 is stored.

  The provisional positioning position latitude data 356 stores the latitude of the provisional positioning position that is provisionally calculated by the positioning calculation (hereinafter referred to as “provisional positioning position latitude”). The provisional positioning position latitude is calculated in the geomagnetism-based two-dimensional positioning process.

  In the positioning data 357, positioning positions represented by latitude, longitude, and altitude are accumulated and stored in chronological order for each positioning. In the baseband process, the CPU 31 accumulates and stores the positioning position obtained by the positioning process in the positioning data 357.

  The TCXO 40 is a temperature compensated crystal oscillator that generates an oscillation signal having a predetermined oscillation frequency, and outputs the generated oscillation signal to the RF reception circuit unit 20 and the baseband processing circuit unit 30.

  The geomagnetism detection unit 50 is a functional unit configured with a sensor for detecting geomagnetism, and includes a geomagnetic sensor 51 and an acceleration sensor 53.

  The geomagnetic sensor 51 is a triaxial geomagnetic sensor composed of an element whose resistance value or impedance value increases or decreases depending on the strength of the magnetic field, for example, and outputs the detection result to the baseband processing circuit unit 30.

  The acceleration sensor 53 is a triaxial acceleration sensor composed of an element whose resistance value is increased or decreased by an external force, for example, and outputs a detection result to the baseband processing circuit unit 30. In the present embodiment, it is used for detecting a gravitational acceleration vector for determining the attitude (tilt) of the mobile phone 1.

  The host CPU 60 is a processor that comprehensively controls each unit of the mobile phone 1 according to various programs such as a system program stored in the ROM 110.

  The operation unit 70 is an input device including, for example, a touch panel, a button switch, and the like, and outputs a pressed key or button signal to the host CPU 60. By operating the operation unit 70, various instructions such as a call request and a mail transmission / reception request are input.

  The display unit 80 is configured by an LCD (Liquid Crystal Display) or the like, and is a display device that performs various displays based on display signals input from the host CPU 60. The display unit 80 displays a navigation screen, time information, and the like.

  The cellular phone antenna 90 is an antenna that transmits and receives cellular phone radio signals to and from a radio base station installed by a communication service provider of the cellular phone 1.

  The cellular phone wireless communication circuit unit 100 is a cellular phone communication circuit unit configured by an RF conversion circuit, a baseband processing circuit, and the like, and performs modulation and demodulation of the cellular phone radio signal so as to make calls and mails. Realize transmission / reception and so on.

  The ROM 110 stores a system program for controlling the mobile phone 1 and various programs and data for realizing a navigation function.

  The RAM 120 forms a work area that temporarily stores a system program executed by the host CPU 60, various processing programs, data being processed in various processing, processing results, and the like.

3. Processing Flow FIG. 8 is a flowchart showing the flow of baseband processing executed in the baseband processing circuit unit 30 when the CPU 31 reads out and executes the baseband processing program 331 stored in the ROM 33. is there. Prior to baseband processing, the digitized IF signal is input to the baseband processing circuit unit 30 through reception of an RF signal by the GPS antenna 5 and down-conversion to an IF signal by the RF receiving circuit unit 20 as needed. Suppose you are in a state that

  First, the CPU 31 performs satellite capturing / tracking processing (step A1), and captures and tracks a GPS satellite signal from the IF signal input from the RF receiving circuit unit 20. Here, it is assumed that the CPU 31 captures and tracks the GPS satellite signal in software, but for example, a code loop known as a delay locked loop (DLL (Delay Locked Loop)) or a phase locked loop (PLL It may be performed in hardware by a circuit such as a carrier loop known as Phase Locked Loop)).

  Next, the CPU 31 calculates a satellite position 3513, a satellite moving direction 3515, and a satellite velocity 3517 based on the GPS satellite signal captured and tracked in step A1, and stores them in the satellite data 351 of the RAM 35 in association with the satellite number 3511. (Step A3). Thereafter, the CPU 31 determines the number of captured satellites (step A5), and when determining that the number of captured satellites is 0 or 1 (step A5; 0 or 1), returns to step A1.

  When it is determined in step A5 that the number of captured satellites is three (step A5; three), the CPU 31 performs a two-dimensional positioning process for measuring the current position of the mobile phone 1 by two-dimensional positioning (step S5). A7). If it is determined that the number of captured satellites is four or more (step A5; four or more), a three-dimensional positioning process is performed to measure the current position of the mobile phone 1 by three-dimensional positioning (step A9). . Since processing related to two-dimensional positioning and three-dimensional positioning is well known, detailed description thereof is omitted.

  On the other hand, when it is determined in step A5 that the number of captured satellites is two (step A5; two), the CPU 31 reads and executes the geomagnetically utilized two-dimensional positioning program 3311 stored in the ROM 33. Then, geomagnetically utilized two-dimensional positioning processing is performed (step A11).

FIG. 9 is a flowchart showing the flow of geomagnetically utilized two-dimensional positioning processing.
First, the CPU 31 acquires a detection result from the geomagnetic sensor 51 and stores it in the geomagnetic sensor data 352 of the RAM 35 (step B1). Further, the CPU 31 acquires a detection result from the acceleration sensor 53 and stores it in the acceleration sensor data 353 of the RAM 35 (step B3).

  Next, the CPU 31 calculates a geomagnetic vector having declination, depression and total magnetic force as elements based on the detection result acquired from the geomagnetic sensor 51 in step B1 and the detection result acquired from the acceleration sensor 53 in step B3. Then, it is stored in the geomagnetic vector data 354 of the RAM 35 (step B5).

  Thereafter, the CPU 31 refers to the latitude-based geomagnetic data 333 stored in the ROM 33, calculates (converts) the latitude 3331 from the dip angle 3333 of the geomagnetic vector calculated in step B5, and calculates the geomagnetic calculated latitude of the RAM 35 as the geomagnetic calculated latitude. The data 355 is stored (step B7).

  Next, the CPU 31 calculates a pseudorange for each of the two captured satellites by multiplying the radio wave propagation time by the speed of light (step B9). Further, the CPU 31 calculates the distance from the earth center to the ground surface (step B11). When the altitude of the mobile phone 1 is known, the distance from the center of the earth to the altitude may be calculated.

  Thereafter, the CPU 31 sets an initial value for positioning calculation (step B13). As an initial value, an arbitrary value can be set for the first positioning after starting GPS, and the previous positioning result can be set for the second and subsequent positioning.

  Thereafter, the CPU 31 executes convergence calculation (positioning calculation) based on the successive approximation calculation method using the pseudo distance calculated in step B9, the distance calculated in step B11, and the initial value set in step B13 ( Step B15).

  Then, the CPU 31 calculates the latitude, longitude, and altitude from the convergence value of the convergence calculation to obtain a provisional positioning position (step B17), and uses the latitude of the provisional positioning position as the provisional positioning position calculation latitude to provisional positioning position latitude data 356 in the RAM 35. (Step B19). Note that the mutual conversion between the coordinate value and the latitude, longitude, and altitude is realized using a known method, and thus the description thereof is omitted.

  Next, the CPU 31 determines whether or not the latitude difference between the geomagnetic calculated latitude stored in the geomagnetic calculated latitude data 355 of the RAM 35 and the temporary positioning position latitude stored in the temporary positioning position latitude data 356 is equal to or smaller than a predetermined threshold value. If it is determined that the threshold value is exceeded (Step B21; No), a value different from the initial value set in Step B13 is reset as the initial value for positioning calculation (Step B21). B23). And CPU31 returns to step B15, and performs positioning calculation again.

  On the other hand, if it is determined in step B21 that the latitude difference is equal to or smaller than the threshold value (step B21; Yes), the CPU 31 determines the temporary positioning position obtained in step B17 as the positioning position and stores it in the positioning data 357 of the RAM 35. Store (step B25). Then, the CPU 31 ends the geomagnetic utilization two-dimensional positioning process.

  In addition, when it was determined in step B21 that the provisional positioning position latitude is deviated from the geomagnetic positioning position, it has been described that the initial value is reset and the positioning calculation is performed again. The geomagnetic-based two-dimensional positioning process may be terminated without performing the above.

  Returning to the baseband process of FIG. 8, after performing the positioning process of any of steps A7, A9 and A11, the CPU 31 outputs the positioning position obtained by the positioning process to the host CPU 60 (step A13).

  Next, the CPU 31 determines whether or not to end positioning (step A15). Specifically, when a positioning end instruction is input from the host CPU 60, it is determined that positioning is to be ended. If it is determined that the positioning is not yet finished (step A15; No), the CPU 31 returns to step A1, and if it is determined that the positioning is finished (step A15; Yes), the baseband processing is terminated.

4). According to the present embodiment, the latitude of the current position is calculated from the detection result by the geomagnetic detection unit 50,
The current position is determined based on the GPS satellite signal received from the captured GPS satellite and the latitude calculated from the geomagnetic detection result. More specifically, when it is detected that the number of captured GPS satellites is two, based on the detection results of the geomagnetic sensor 51 and the acceleration sensor 53, the depression angle, the declination angle, and the total magnetic force are elements. The geomagnetic vector is calculated, and the latitude is calculated from the dip angle of the geomagnetic vector to obtain the geomagnetic calculated latitude. Then, a pseudo distance from the GPS satellite that has transmitted the received GPS satellite signal is calculated, and a positioning operation for specifying the current position is performed from the calculated pseudo distance and the geomagnetic calculated latitude.

  That is, by using the geomagnetic calculation latitude as so-called assist information for positioning, the current position can be measured even when a sufficient number of GPS satellites cannot be captured. The calculated geomagnetic latitude indicates the latitude of the current position of the mobile phone 1. Therefore, when the latitude of the positioning position calculated provisionally deviates from the latitude calculated by geomagnetism, the provisional positioning position is highly likely to be an incorrect positioning result. In this embodiment, when the latitude difference between the latitude of the provisional positioning position and the geomagnetic calculation latitude is equal to or less than a predetermined threshold, the provisional positioning position is determined to be an appropriate positioning result, so that an incorrect positioning result is obtained. Can be avoided.

5. Modified example 5-1. Positioning Device The present invention can be similarly applied to a portable navigation device, an in-vehicle navigation device, a wristwatch, and the like in addition to the portable phone.

5-2. Correction of Temporary Positioning Position, etc. The temporary positioning position may be corrected based on the geomagnetic calculated latitude. In this case, the second geomagnetism-based two-dimensional positioning program is stored in the ROM 33 as a subroutine of the baseband processing program 331. Then, the CPU 31 performs the second geomagnetic utilization two-dimensional positioning process according to the second geomagnetism utilization two-dimensional positioning program in step A11 of the baseband process.

  FIG. 10 is a flowchart showing the flow of the second geomagnetism-based two-dimensional positioning process. Note that the same steps as those in the geomagnetism-based two-dimensional positioning process in FIG.

  In the second geomagnetism-based two-dimensional positioning process, after the provisional positioning position latitude is stored in the RAM 35 in step B19, the CPU 31 corrects the provisional positioning position latitude to the geomagnetic calculation latitude (step C1). Then, the CPU 31 stores the corrected provisional positioning position in the RAM 35 as a positioning position (step C3), and ends the second geomagnetism-based two-dimensional positioning process.

  There are various methods for correcting the provisional positioning position. For example, the provisional positioning position latitude may be corrected to an intermediate latitude between the provisional positioning position latitude and the geomagnetic calculation latitude. Further, the degree of correction may be determined based on the position error included in the temporary positioning position. For example, the provisional positioning position latitude is corrected to be closer to the geomagnetic calculation latitude as the position error included in the provisional positioning position is larger.

  Since the geomagnetic calculated latitude represents the latitude of the current position of the mobile phone 1, the current position can be appropriately obtained by correcting the provisional positioning position calculated by the positioning calculation based on the geomagnetic calculated latitude.

  Further, the positioning position obtained by the two-dimensional positioning process or the three-dimensional positioning process may be corrected based on the geomagnetic calculated latitude. In this case, the second baseband processing program is stored in the ROM 33, and the CPU 31 performs the second baseband processing according to the second baseband processing program.

  FIG. 11 is a flowchart showing the flow of the second baseband process. Note that the same steps as those in the baseband processing in FIG.

  In step A5, the CPU 31 determines the number of captured satellites. If it is determined that the number is 2 or less (step A5; 2 or less), the CPU 31 returns to step A1 to perform satellite capture / tracking processing. When it is determined that the number of captured satellites is three (step A5; three), two-dimensional positioning processing is performed (step A7), and when it is determined that the number is four or more (step A5; 4). 3 or more) 3D positioning processing is performed (step A9).

  After performing the positioning process in step A7 or A9, the CPU 31 acquires the detection result from the geomagnetic sensor 51 and stores it in the RAM 35 (step D1), and acquires the detection result from the acceleration sensor 53 and stores it in the RAM 35 ( Step D3).

  Next, the CPU 31 calculates a geomagnetic vector based on the detection result acquired from the geomagnetic sensor 51 in step D1 and the detection result acquired from the acceleration sensor 53 in step D3, and stores it in the RAM 35 (step D5). Then, the CPU 31 calculates the latitude from the dip angle of the geomagnetic vector calculated in step D5, and stores it in the RAM 35 as the geomagnetic calculated latitude (step D7).

  Then, CPU31 correct | amends the latitude of the positioning position calculated | required by the positioning process to the geomagnetism calculation latitude calculated by step D7 (step D9). And CPU31 updates the positioning position memorize | stored in RAM35 by the correction result of step D9 (step D11), and outputs the said positioning position to host CPU60 (step A13).

5-3. Conditions for Reception Status In the above-described embodiment, it has been described that positioning using geomagnetism is performed when the number of captured satellites is two. In other words, the number of captured GPS satellite signals (GPS satellites) is set as a condition of the reception status for performing positioning using geomagnetism, and positioning using geomagnetism is performed when the condition is satisfied. become.

  Other conditions for reception status for positioning using geomagnetism can be set as appropriate. Specifically, the condition of the signal strength of the captured GPS satellite signal can be set as the condition of the reception status. For example, among all the acquired GPS satellite signals, the number of GPS satellite signals whose signal intensity is below a predetermined threshold has reached 50%, or the average value of the signal intensity of the acquired GPS satellite signals is predetermined. It may be set as a condition of the reception status that the value is equal to or less than the threshold.

  In this case, when the mobile phone 1 is located in an urban canyon environment or the like, positioning using geomagnetism is performed, and it is effective that a positioning error occurs due to the influence of multipath. Can be prevented. In this case, the satellite signals used for the pseudorange calculation may be appropriately selected such as two signals having the strongest signal strength.

5-4. Calculation of Latitude In the above-described embodiment, it has been described that the latitude is calculated from the dip angle of the geomagnetic vector. However, the latitude may also be calculated using a declination. In this case, as the latitude-specific geomagnetic data 333 of the ROM 33, data in which the latitude is associated with the dip angle and the declination of the geomagnetic vector is stored. Then, the CPU 31 calculates the latitude from the dip and declination of the geomagnetic vector to obtain the geomagnetic calculated latitude, and measures the current position using the calculated geomagnetic latitude.

  By calculating the latitude using not only the dip angle but also the declination of the geomagnetic vector, it becomes possible to more accurately determine the latitude of the current position of the mobile phone 1, which in turn contributes to improved positioning accuracy. .

5-5. Differentiation of Processing The host CPU 60 may perform part or all of the processing performed by the CPU 31. For example, satellite acquisition / tracking processing and satellite information calculation are performed by the CPU 31, and the number of captured satellites and positioning processing are performed by the host CPU 60.

(A) Explanatory drawing of a pseudo distance. (B) Explanatory drawing of the principle of position specification. (A) Explanatory drawing of the outline of geomagnetism. (B) Explanatory drawing of the element of geomagnetism. The block diagram which shows the function structure of a portable telephone. The figure which shows the data structural example of ROM. The figure which shows the data structural example of RAM. The figure which shows the data structural example of the geomagnetic data according to latitude. The figure which shows the data structural example of satellite data. The flowchart which shows the flow of a baseband process. The flowchart which shows the flow of a geomagnetic utilization two-dimensional positioning process. The flowchart which shows the flow of a 2nd geomagnetic 2D positioning process. The flowchart which shows the flow of a 2nd baseband process.

Explanation of symbols

1 mobile phone, 5 GPS antenna, 10 GPS receiver,
20 RF receiving circuit section, 30 baseband processing circuit section, 40 TCXO,
50 geomagnetism detector, 51 geomagnetic sensor, 53 acceleration sensor,
60 host CPU, 70 operation unit, 80 display unit, 90 mobile phone antenna,
100 wireless communication circuit unit for mobile phone, 110 ROM, 120 RAM

Claims (13)

A receiving unit for receiving a positioning signal transmitted from a positioning satellite;
A geomagnetism detector for detecting geomagnetism,
A latitude calculator that calculates the latitude of the current position from the detection result by the geomagnetism detector;
A positioning unit for positioning the current position based on the positioning signal received by the receiving unit and the latitude calculated by the latitude calculating unit;
Positioning device equipped with. The geomagnetism detection unit includes a triaxial geomagnetic sensor and an acceleration sensor, and is configured to detect an absolute geomagnetic vector at the current position regardless of the posture of the device itself.
The latitude calculation unit calculates the latitude based on at least the dip angle of the geomagnetic vector detected by the geomagnetism detection unit;
The positioning device according to claim 1. The positioning unit is
Based on the positioning signal received by the receiving unit, a pseudo distance calculating unit that calculates a pseudo distance from the positioning satellite that has transmitted the positioning signal;
Latitude information using positioning status detection unit for detecting that the reception status of the positioning signal by the receiving unit satisfies a condition predetermined as a reception status condition for performing positioning using latitude information;
A latitude information using positioning unit that performs a positioning operation to identify a current position from the pseudo distance calculated by the pseudo distance calculating unit and the latitude calculated by the latitude calculating unit at the time of detection;
The positioning device according to claim 1 or 2, comprising: The positioning unit is
Based on the positioning signal received by the receiving unit, a pseudo distance calculating unit that calculates a pseudo distance from the positioning satellite that has transmitted the positioning signal;
A provisional positioning position calculation unit that calculates a provisional positioning position from the pseudo distance calculated by the pseudo distance calculation unit;
The current position for determining whether the latitude of the provisional positioning position calculated by the provisional positioning position calculation unit and the latitude calculated by the latitude calculation unit are appropriate, and determining the provisional positioning position as the current position when it is determined to be appropriate A position determining unit;
The positioning device according to any one of claims 1 to 3, further comprising: The positioning unit is
Based on the positioning signal received by the receiving unit, a pseudo distance calculating unit that calculates a pseudo distance from the positioning satellite that has transmitted the positioning signal;
A provisional positioning position calculation unit that calculates a provisional positioning position from the pseudo distance calculated by the pseudo distance calculation unit;
A current position correction calculating unit that calculates the current position by correcting the temporary positioning position calculated by the temporary positioning position calculating unit based on the latitude calculated by the latitude calculating unit;
The positioning device according to any one of claims 1 to 3, further comprising:   The positioning according to claim 5, wherein the current position correction calculation unit calculates the current position by correcting the latitude of the temporary positioning position calculated by the temporary positioning position calculation unit to the latitude calculated by the latitude calculation unit. apparatus. It is a positioning method of the current position using a geomagnetism detection unit that detects geomagnetism,
A receiving step for receiving a positioning signal transmitted from a positioning satellite;
A latitude calculating step for calculating the latitude of the current position from the detection result by the geomagnetic detector;
A positioning step of positioning the current position based on the positioning signal received in the receiving step and the latitude calculated in the latitude calculating step;
Positioning method including. The geomagnetism detection unit includes a triaxial geomagnetic sensor and an acceleration sensor, and is configured to detect an absolute geomagnetic vector at the current position regardless of the posture of the device itself.
The latitude calculating step is a step of calculating the latitude based on at least the dip angle of the geomagnetic vector detected by the geomagnetic detection unit.
The positioning method according to claim 7. The positioning step includes
Based on the positioning signal received in the receiving step, a pseudo distance calculating step for calculating a pseudo distance from a positioning satellite that has transmitted the positioning signal;
Latitude information use positioning status detection step for detecting that the reception status of the positioning signal in the receiving step satisfies a condition predetermined as a reception status condition for performing positioning using latitude information;
A latitude information using positioning step for performing a positioning operation to identify a current position from the pseudo distance calculated in the pseudo distance calculating step and the latitude calculated in the latitude calculating step during the detection;
The positioning method according to claim 7 or 8, comprising: The positioning step includes
Based on the positioning signal received in the receiving step, a pseudo distance calculating step for calculating a pseudo distance from a positioning satellite that has transmitted the positioning signal;
A provisional positioning position calculation step for calculating a provisional positioning position from the pseudo distance calculated in the pseudo distance calculation step;
The current position of determining the appropriateness of the latitude of the provisional positioning position calculated in the provisional positioning position calculation step and the latitude calculated in the latitude calculation step, and determining the provisional positioning position as the current position when determined appropriate A positioning step;
The positioning method according to any one of claims 7 to 9, comprising: The positioning step includes
Based on the positioning signal received in the receiving step, a pseudo distance calculating step for calculating a pseudo distance from a positioning satellite that has transmitted the positioning signal;
A provisional positioning position calculation step for calculating a provisional positioning position from the pseudo distance calculated in the pseudo distance calculation step;
A current position correction calculating step for correcting the temporary positioning position calculated in the temporary positioning position calculating step based on the latitude calculated in the latitude calculating step and calculating a current position;
The positioning method according to any one of claims 7 to 9, comprising:   The current position correction calculation step is a step of calculating the current position by correcting the latitude of the temporary positioning position calculated in the temporary positioning position calculation step to the latitude calculated in the latitude calculation step. The positioning method described.   The program for making the computer provided with the geomagnetism detection part which detects geomagnetism perform the positioning method as described in any one of Claims 7-12.

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