JP2009133702A - Positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of positioning precision that is caused when performing positioning such a cycle while performing positioning at a high frequency. <P>SOLUTION: A positioning device is composed of: a GPS positioning means configured to perform GPS positioning in at least two kinds of cycles by using a GPS signal; a GPS positioning precision determining means for determining whether the precision of the GPS positioning is low based on a prescribed condition; and a final positioning result calculating means for calculating final positioning results based on GPS positioned results in a first cycle with the GPS positioning means when it is determined that the precision of the GPS positioning is low, and calculating the final positioning results based on the GPS positioned results in a second cycle shorter than the first cycle with the GPS positioning means when it is determined that the precision of the GPS positioning is not low. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a positioning device that performs positioning using GPS (Global Positioning System), and more particularly, to a positioning device that can change a positioning frequency according to a predetermined condition.

  GPS is a positioning system for measuring position information and the like of an object using a GPS signal transmitted from a GPS satellite orbiting the earth, and is widely used in daily life.

  In GPS, a plurality of GPS satellites share the same frequency band and transmit a GPS signal by a CDMA (Code Division Multiple Access) method. That is, the GPS signal is 1575.42 MHz by a navigation message as a communication signal including GPS satellite orbit information and clock information and a PRN code (Pseudo Random Noise code) as a spread code determined for each GPS satellite. The carrier is obtained by BPSK (Binary Phase Shift Keying) modulation. The GPS receiver selects the number of GPS satellites more than necessary in principle, generates a PRN code corresponding to the selected GPS satellite, and multiplies the phase of the generated PRN code in synchronization with the GPS signal to multiply the navigation data. Is demodulated. And it calculates using the navigation data obtained by demodulating, and obtains position information, moving speed, etc. of the object. Hereinafter, position measurement, movement speed measurement, and the like using GPS by a GPS receiver are referred to as “GPS positioning”.

  An end-user product including a GPS receiver includes a car navigation device mounted on a passenger car or the like. In addition to GPS positioning, the car navigation system also performs well-known DR positioning using a DR (dead reckoning) sensor, and the final positioning result is obtained from the positioning results of both systems so as to complement the weaknesses of the two positioning methods. calculate. And based on the positioning result obtained by calculation, the own vehicle position displayed on a screen is updated. Further, when the destination is set by the user, the car navigation device performs navigation toward the destination together with the update of the vehicle position on the screen.

  Usually, a GPS receiver provided in such a car navigation apparatus is configured to perform GPS positioning once per second as disclosed in Patent Document 1. However, in order to show the movement of the vehicle position on the screen smoothly, it is necessary to update the display of the vehicle position a plurality of times per second. For this reason, the car navigation device performs DR positioning a plurality of times per second, and when only the GPS positioning data is updated without updating the GPS positioning result, the vehicle position is updated using only the DR positioning result. It is configured.

  By the way, the DR positioning result is obtained by adding the movement distance and the direction change calculated based on the output of the DR sensor to the previous positioning result. For this reason, when an error is included in the previous positioning result, there is a problem that the error is inherited in the newly calculated DR positioning result. Therefore, there is an idea that a GPS positioning result that is not influenced by the previous positioning result is obtained at shorter time intervals, and the accuracy of the positioning result finally obtained is improved.

From such an idea, a GPS receiver capable of performing GPS positioning n (n is a natural number of 2 or more) times per second has been developed and put into practical use for a car navigation apparatus. Hereinafter, for convenience of explanation, GPS positioning performed at a frequency of once per second is referred to as “1 Hz positioning”, and GPS positioning performed at a frequency of n times per second is also referred to as “nHz positioning”. Some car navigation devices learn DR sensor characteristics (such as a distance coefficient of a vehicle speed sensor) using a GPS positioning result. In the case of nHz positioning, the effect of speeding up the learning of the DR sensor is expected as the frequency of GPS positioning is improved.
JP 2003-344066 A

  However, when a GPS receiver that performs nHz positioning is adopted as the GPS receiver of the car navigation device, the following problems are concerned. That is, the GPS receiver performs speed measurement based on a frequency change amount (hereinafter referred to as “Doppler shift amount”) with respect to the original carrier frequency due to a Doppler effect corresponding to a relative speed between the GPS satellite and the GPS receiver. The Doppler shift amount is the number of rotations per unit time of the phase of the actually received carrier (hereinafter referred to as “phase rotation number”), and the phase rotation when the original carrier frequency (without Doppler shift) is counted. It is obtained by calculating the difference with the number. However, in the case of a GPS receiver that performs nHz positioning, since the time of GPS positioning per one time is shorter than the conventional (1 Hz positioning), the number of phase rotations counted within the positioning time is also reduced, and the phase rotation number is 1 The measurement error caused by one count error increases. In particular, when the passenger car is stopped or traveling at a low speed, the Doppler shift amount resulting from the movement of the passenger car is reduced, leading to a significant decrease in accuracy of speed measurement.

  Furthermore, a general GPS receiver has a configuration in which each measurement result (speed measurement result, positioning result, etc.) is processed and output by a Kalman filter. For this reason, the error of the speed measurement result also affects the positioning result of the position, thereby reducing the positioning accuracy. Therefore, in a car navigation device equipped with a GPS receiver that performs nHz positioning, when the passenger vehicle is stopped or traveling at low speed, the position of the vehicle on the screen is frequently updated based on the GPS positioning result with low accuracy, There may be frequent jumps in the position of the vehicle on the screen.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a positioning device that enables high-frequency positioning while suppressing a decrease in positioning accuracy.

  A positioning apparatus according to one aspect of the present invention that solves the above-described problems is based on GPS positioning means configured to be able to perform GPS positioning in at least two types of cycles using a GPS signal, and based on a predetermined condition. GPS positioning accuracy determining means for determining whether or not the GPS positioning accuracy is low, and when it is determined that the GPS positioning accuracy is low, the GPS positioning means is based on the result of GPS positioning in the first period. When the final positioning result is calculated and it is determined that the accuracy of the GPS positioning is not low, the final positioning result is determined based on the result of the GPS positioning means performing the GPS positioning in the second cycle shorter than the first cycle. And a final positioning result calculation means for calculating a positioning result.

  The positioning device configured in this way suppresses a decrease in the accuracy of the final positioning result by reducing the positioning frequency under the condition that the accuracy of the GPS positioning is low, and the accuracy of the GPS positioning is high. Under the condition to be determined, the accuracy of the final positioning result can be improved by increasing the positioning frequency.

  Note that the positioning device further includes, for example, a moving speed detection unit that detects the moving speed of the positioning device. In the case of such a configuration, the GPS positioning accuracy determination means determines that the accuracy of GPS positioning by the second period is low when the movement speed detected by the movement speed detection means falls below the first threshold.

  In addition, the positioning device is configured to further include an area determination unit that determines whether or not the device is located in a predetermined area, for example. In such a configuration, the GPS positioning accuracy determination means determines that the accuracy of GPS positioning is low when it is determined that the GPS positioning accuracy is located in a predetermined area.

  The predetermined area here is, for example, an area with low GPS positioning accuracy. Moreover, an area with low GPS positioning accuracy is an area with many multipath waves, for example. An area with many multipath waves is, for example, an urban area.

  Even if it is determined that the positioning device is located in a predetermined area, the GPS positioning accuracy determination means does not have low GPS positioning accuracy when the movement speed detected by the movement speed detection means exceeds the second threshold. It is good also as a structure to determine.

  Here, the GPS positioning means includes, for example, at least two GPS receivers that perform GPS positioning at different periods. In this case, the final positioning result calculation means selects one GPS receiver based on the determination result of the GPS positioning accuracy determination means, and calculates the final positioning result based on the GPS positioning result of the selected GPS receiver. Will be calculated.

  The GPS positioning means is a single GPS receiver configured to be able to change the GPS positioning cycle. When it is determined that the accuracy of the GPS positioning is low, the GPS positioning unit performs GPS positioning in the first cycle, If it is determined that the positioning accuracy is not low, GPS positioning is performed in the second cycle.

  Further, the positioning device may include a DR sensor and DR positioning means that performs DR positioning based on the output of the DR sensor. In this case, the final positioning result calculation means calculates the final positioning result based on the results of GPS positioning and DR positioning.

  According to the positioning device of the present invention, under the condition that it is determined that the accuracy of GPS positioning is low, it is possible to suppress a decrease in accuracy of the final positioning result by performing positioning at a low positioning frequency, and when the accuracy of GPS positioning is high. Under the conditions to be determined, the accuracy of the final positioning result can be improved by performing positioning at a high positioning frequency.

  Hereinafter, the configuration and operation of the car navigation device according to the embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the navigation device 200. As shown in FIG. 1, the navigation device 200 includes a GPS receiver 100, 100 ′, a gyro sensor 102, a vehicle speed sensor 104, A / D conversion units 102a, 104a, a gate array 106, a CPU (Central Processing Unit) 108, a ROM (Read Only Memory) 110, RAM (Random Access Memory) 112, HDD (Hard Disk Drive) 114, display 116, and input unit 118. The CPU 108 controls the entire navigation device 200 and implements various functions through cooperative operations with each component of the navigation device 200.

  Each of the GPS receivers 100 and 100 ′ captures and tracks more than the number of GPS signals necessary for GPS positioning from a plurality of GPS satellites, performs 1 Hz positioning and nHz positioning, and obtains the obtained GPS positioning results as a gate array. The data is output to the CPU 108 via 106. The gate array 106 is wired according to the specifications.

  The gyro sensor 102 and the vehicle speed sensor 104 are well-known DR sensors. The gyro sensor 102 measures the angular velocity related to the direction in the horizontal plane of the vehicle on which the car navigation device 200 is mounted, and outputs the measurement result to the A / D conversion unit 102a. Moreover, the vehicle speed sensor 104 detects the rotational speed of the left and right drive wheels of the vehicle, and outputs the number of pulses corresponding to the detection result to the A / D converter 104a. The signals input to the A / D converters 102 a and 104 a are converted into digital signals and then input to the CPU 108 via the gate array 106.

  The ROM 110 stores various programs for executing navigation processing. These programs are expanded in the work area of the RAM 112 when the navigation device 200 is activated. The CPU 108 executes the program on the work area and appropriately reads the map data stored in the HDD 114 to display the map on the display 116.

  Specifically, the CPU 108 performs DR positioning calculation based on the output of each DR sensor, and acquires the DR positioning result. Next, the DR positioning result and the GPS positioning result of either one of the GPS receivers 100 and 100 'are compared in consideration of the estimated error value for each positioning result. Then, a positioning result determined to have high accuracy is selected based on the comparison result, and the selected positioning result is determined as a final positioning result (hereinafter referred to as “final positioning result”). When there is no output of the GPS positioning result, the DR positioning result is set as the final positioning result without performing the above comparison process. Then, the CPU 108 searches a map database stored in the HDD 114 based on the determined positioning result, and extracts a corresponding map image. Finally, map matching is performed, and the vehicle position mark is superimposed on the extracted map image and displayed on the display 116. At this time, if the user operates the input unit 118 to set a destination, the CPU 108 also performs a navigation process toward the destination.

  Next, the GPS receiver 100 will be described in detail. Note that the GPS receivers 100 and 100 'have substantially the same configuration and operation except for the frequency of performing GPS positioning. Therefore, only the GPS receiver 100 is described here, and the description of the GPS receiver 100 'is omitted.

  FIG. 2 is a block diagram showing the configuration of the GPS receiver 100. As shown in FIG. 2, the GPS receiver 100 includes a down converter unit 1, a received signal processing unit 2, and a positioning calculation control unit 3. The down-converter unit 1 receives the GPS signal, converts it to an intermediate frequency, and then outputs it to the received signal processing unit 2. The reception signal processing unit 2 and the positioning calculation control unit 3 operate in cooperation to execute GPS signal acquisition, tracking, and positioning processes using the signal output from the down converter unit 1. The positioning calculation control unit 3 outputs the GPS positioning result obtained by the cooperative operation with the received signal processing unit 2 to the CPU 108 via the gate array 106.

  The down converter unit 1 includes a GPS antenna 10, an RF (radio frequency) input unit 11, a BPF (Band Pass Filter) 12 and 14, an LNA (Low Noise Amplifier) 13, a down converter 15, an AGC (Auto Gain Control) 16, a TCXO. (Temperature Compensated Crystal Oscillator) 17, frequency synthesizer 18, and A / D converter 19.

  A GPS signal transmitted from a GPS satellite is received by the GPS antenna 10 and input to the BPF 12 via the RF input unit 11. Next, this input signal (hereinafter referred to as “RF signal”) is filtered to a predetermined band by the BPF 12, and noise outside the GPS band is attenuated through the LNA 13 and BPF 14 which are low noise amplifiers, and then input to the down converter 15. To do.

  The TCXO 17 is a local oscillator that oscillates at a predetermined frequency, and the oscillation frequency is lower than the frequency of the RF signal input to the down converter 15. Further, the frequency synthesizer 18 generates a local oscillator signal based on the input from the TCXO 17 and outputs it to the down converter 15. The down converter 15 converts the RF signal into an intermediate frequency advantageous for signal processing, that is, an IF (Intermediate Frequency) signal under the control of the AGC 16 using the input local oscillator signal and outputs it to the A / D converter 19. To do.

  The A / D converter 19 samples the IF signal, performs quadrature demodulation, and converts it into an I (In-phase) signal and a Q (Quadra-phase) signal. The I signal is an in-phase component at the time of quadrature demodulation, and the Q signal is a component that is orthogonal to the I signal. Hereinafter, for convenience of explanation, the I signal and the Q signal are collectively referred to as an “IQ signal”. The A / D converter 19 outputs the IQ signal obtained by the conversion process to the received signal processor 2.

  The reception signal processing unit 2 includes a channel 21 and an NCO (Number Controlled Oscillator) 22. The reception signal processing unit 2 is configured to include a plurality of channels 21 so that GPS signals from a plurality of GPS satellites can be simultaneously captured and tracked by the CDMA method.

  The positioning calculation control unit 3 includes a CPU 31, an RTC (Real-Time Clock) 32, a ROM 33, a RAM 34, and an interface 35. The CPU 31 operates based on a clock output from the frequency synthesizer 18 and performs overall control of the reception signal processing unit 2 and the positioning calculation control unit 3. The RTC 32 is a clock IC (Integrated Circuit) that is operated by a crystal oscillator (not shown), and functions as a time measuring means. The ROM 33 stores programs and data for performing positioning calculations. The program is expanded in the work area of the RAM 34 when the navigation device 200 is activated. The CPU 31 operates according to a program developed on the work area, controls the NCO 22, and performs a positioning calculation based on a signal from each channel 21. Then, the GPS positioning result obtained by the calculation is output to the CPU 108 via the interface 35 and the gate array 106.

  Specifically, the CPU 31 determines the Doppler shift amount of the IQ signal input to each channel 21 based on the navigation message acquired by the previous positioning, the previous GPS positioning result, the current time measured by the RTC 32, and The search range of the phase of the PRN code necessary for capturing the GPS signal is estimated, and the Doppler shift amount and the set value of the search range are generated based on the estimation result and output to the NCO 22. The CPU 31 designates a PRN code to be searched for in each channel 21 through the NCO 22 for each channel 21 so that GPS signals of different GPS satellites are captured and tracked in each channel 21.

  The NCO 22 operates based on the clock output from the frequency synthesizer 18, generates a reference code for the PRN code based on the set value from the CPU 31, and performs necessary data exchange with each channel 21 to set each channel 21. Control.

  Each channel 21 performs Doppler shift compensation on the IQ signal from the A / D converter 19 based on the Doppler shift amount set by the CPU 31 under the control of the NCO 22. Similarly, the PRN code included in the GPS signal and the reference code (that is, generated on the GPS receiver 100 side) are multiplied and multiplied by the PRN code reference code and the IQ signal within the search range set by the CPU 31. A correlation value with the PRN code is obtained. Each channel 21 captures the IQ signal, that is, the GPS signal, when the obtained correlation value exceeds a predetermined threshold value. In addition, the influence of the noise contained in a GPS signal can be removed and the capture sensitivity rises, so that the time of the integration process at this time is set longer. This integration processing time is also set by the CPU 31.

  The CPU 31 detects the phase difference between the IQ signal captured by each channel 21 and the reference code based on the correlation value obtained by each channel 21, and synchronizes the phase of the reference code with the phase of the IQ signal. The IQ signal is demodulated to obtain navigation data. Further, the CPU 31 performs feedback control corresponding to each channel 21 and performs tracking control of the GPS signal captured by each channel 21 by performing feedback control of the NCO 22 so that the output value of each channel 21 is maximized. . Note that if the acquisition and tracking of the GPS signal fails, the CPU 31 re-attempts to acquire and track the GPS signal after resetting the search range. When the total number of GPS signals captured and tracked on the channel 21 is greater than or equal to the number necessary for GPS positioning, the CPU 31 receives data necessary for positioning including navigation data from each channel 21 to determine the positioning and speed. Measurement is performed, and the GPS positioning result obtained by applying each measurement result to the Kalman filter is output to the CPU 108. As described above, the GPS receiver 100 performs positioning calculation once every second (in the case of the GPS receiver 100 ′, n times per second), and outputs the obtained GPS positioning result to the CPU 108.

  The GPS positioning results obtained in this way are output to the CPU 108 from each of the GPS receivers 100 and 100 '. Then, as described above, the CPU 108 selects any one of the GPS positioning results, and determines the final positioning result using the selected GPS positioning results. FIG. 3 shows a flowchart of a GPS positioning result selection process that is a process executed by the CPU 108 and selects a GPS positioning result used for determining a final positioning result. Hereinafter, the GPS positioning result selection process of FIG. 3 will be described. The CPU 108 repeatedly executes the GPS positioning result selection process of FIG. 3 at a predetermined interval while the car navigation device 200 is operating.

  As shown in FIG. 3, the CPU 108 refers to the DR positioning result (or the previous final positioning result) to determine whether or not the vehicle traveling speed is equal to or higher than a predetermined threshold (step 1, the following specification) And the step is abbreviated as “S” in the drawings). Here, when the traveling speed of the vehicle falls below the predetermined threshold (S1: NO), the vehicle is stopped or in a low-speed traveling state. In this case, as described above, noise is dominant in the Doppler shift amount set by the CPU 31, and the speed measurement value calculated using the set value of the Doppler shift amount tends to be low in accuracy. When the CPU 108 determines the final positioning result using such a positioning result with low accuracy, the final positioning result also decreases as a result. Therefore, the CPU 108 adopts the result of 1 Hz positioning instead of the result of nHz positioning as data used for determining the final positioning result (S4). That is, the CPU 108 reduces the possibility that a positioning result with low accuracy is used in determining the final positioning result, and suppresses a decrease in accuracy of the final positioning result. Thereby, the position jump of the own vehicle position mark or the like on the display 116 does not occur frequently.

  In another embodiment, when the traveling speed of the vehicle falls below a predetermined threshold, the CPU 108 regards any GPS positioning result as low in accuracy, and any GPS positioning result as a determination material for determining the final positioning result. May be operated so that the DR positioning result is used as it is as the final positioning result.

  When the vehicle traveling speed is equal to or higher than the predetermined threshold (S1: YES), the CPU 108 compares the DR positioning result (or the previous final positioning result) with the map database of the HDD 114, and the vehicle is not in the urban area. It is determined whether the vehicle is traveling (S2). Here, the urban area refers to an area in which, for example, high-rise buildings are lined up and multipath is likely to occur. In addition, if it is an area where multipath is likely to occur, it is treated as an area corresponding to an urban area here, even if high-rise buildings are not lined up.

  Therefore, when the vehicle is traveling in an urban area (S2: NO), the CPU 108 determines that the vehicle is in an environment where multipath is likely to occur. If GPS positioning is performed at a high frequency in such an environment where the accuracy of GPS positioning is reduced, the Kalman filter is adversely affected, and the position estimation performance by the Kalman filter is temporarily deteriorated. For this reason, the CPU 108 employs the positioning result of the GPS receiver 100, that is, the result of 1 Hz positioning, which has a low positioning frequency and has little adverse effect on the Kalman filter, as data used for determining the final positioning result (S4).

  In an environment with many multipaths, the accuracy of the GPS positioning result is low in any case. Therefore, in another embodiment, when the vehicle is traveling in an urban area, the CPU 108 regards any GPS positioning result as having low accuracy, and any GPS positioning result as a determination material for determining the final positioning result. May be operated so that the DR positioning result is used as it is as the final positioning result.

  Further, when the vehicle is traveling outside the urban area (S2: YES), because the vehicle is not in an environment with many multipaths, and the traveling speed of the vehicle is equal to or greater than a predetermined threshold, and the Doppler shift amount is large A Doppler shift amount with a high S / N ratio can be obtained. That is, in this case, the GPS receiver 100, 100 'calculates a highly accurate GPS positioning result. Therefore, the CPU 108 adopts the result of nHz positioning as data used for determining the final positioning result (S3). In this case, when determining the final positioning result, more accurate GPS positioning results can be used. Therefore, an effect of improving the accuracy of the final positioning result can be expected.

  That is, the car navigation device 200 according to the present invention adopts 1 Hz positioning to determine the final positioning result in a situation where the accuracy of the GPS positioning result can be lowered, and performs nHz positioning in a situation where a highly accurate GPS positioning result is obtained. Adopt and determine the final positioning result. As a result, the accuracy of the final positioning result is suppressed in the former situation, and the accuracy of the final positioning result is improved in the latter situation.

  The above is the embodiment of the present invention. The present invention is not limited to these embodiments and can be modified in various ranges. For example, the configuration for changing the GPS positioning frequency according to the present embodiment according to a predetermined condition may be adopted for a PND (Personal Navigation Device) that is a simple navigation device that does not hold a map database, a mobile terminal such as a mobile phone, and the like. Can do.

  In addition, the car navigation device 200 may be configured to switch between 1 Hz positioning and nHz positioning with a single GPS receiver. In this case, the GPS receiver receives the DR positioning result via the CPU 108 and performs the determination process of S1. Similarly, the received DR positioning result is compared with the map database of the HDD 114 via the CPU 108, and the determination process of S2 is performed. Then, either 1 Hz positioning or nHz positioning is performed according to the determination result, and the GPS positioning result obtained as a result is output to the CPU 108.

  Moreover, although the car navigation apparatus 200 can be set to two types of positioning frequencies of 1 Hz and nHz positioning, in another embodiment, the positioning frequency of more patterns may be set.

  Further, in the process of S1 in FIG. 3, the vehicle traveling speed is determined with reference to the DR positioning result or the previous final positioning result. Alternatively, the vehicle traveling speed is referred to the previous GPS positioning result. The speed may be determined. In this case, it is desirable to provide a means for detecting when the GPS speed measurement result is an abnormal value. This is because the traveling speed can be determined with high accuracy by not using an abnormal value in the traveling speed determination process. Abnormality detection includes, for example, acceleration abnormality detection (abnormality is detected when an impossible acceleration is measured due to vehicle performance) and speed abnormality detection (abnormality is detected when an impossible speed due to vehicle performance is measured) And so on). Further, an abnormality may be detected by comparison with another speedometer (for example, an abnormality is detected when there is a deviation from the result of the vehicle speed pulse).

  The occurrence of multipath in urban areas is determined by the positional relationship between GPS satellites that transmit GPS signals that reach the GPS receiver 100, buildings that reflect the GPS signals, and vehicles. Therefore, when the vehicle travels at a high speed, the influence of multipath may be small. For this reason, when the vehicle is traveling in an urban area, the CPU 108 adopts nHz positioning and determines the final positioning result only when the traveling speed is equal to or higher than a predetermined threshold (higher than the threshold of S1). It may operate to do.

It is a block diagram which shows the structure of the car navigation apparatus of embodiment of this invention. It is a block diagram which shows the structure of the GPS receiver of embodiment of this invention. It is a flowchart which shows the GPS positioning result selection process performed in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Down converter part 2 Received signal processing part 3 Positioning calculation control part 100, 100 'GPS receiver 102 Gyro sensor 104 Vehicle speed sensor 108 CPU
200 Navigation device

Claims (10)

GPS positioning means configured to be able to perform GPS positioning with at least two types of cycles using a GPS (Global Positioning System) signal;
GPS positioning accuracy determination means for determining whether the accuracy of the GPS positioning is low based on a predetermined condition;
When it is determined that the accuracy of the GPS positioning is low, the GPS positioning means calculates a final positioning result based on the result of GPS positioning in the first period, and the accuracy of the GPS positioning is not low. If determined, the GPS positioning means includes final positioning result calculation means for calculating a final positioning result based on a result of GPS positioning in the second period shorter than the first period. A positioning device characterized by that. A moving speed detecting means for detecting the moving speed of the positioning device;
The positioning according to claim 1, wherein the GPS positioning accuracy determining means determines that the accuracy of GPS positioning according to the second period is low when the detected moving speed is lower than a first threshold. apparatus. Area determining means for determining whether or not the positioning device is located in a predetermined area;
The positioning according to claim 1, wherein the GPS positioning accuracy determining means determines that the accuracy of the GPS positioning is low when it is determined that the GPS positioning is located in the predetermined area. apparatus.   The positioning device according to any one of claims 1 to 3, wherein the predetermined area is an area with low GPS positioning accuracy.   The positioning device according to claim 4, wherein the area with low GPS positioning accuracy is an area with many multipath waves.   6. The positioning device according to claim 5, wherein the area where the multipath wave is large is an urban area.   Even if it is determined that the positioning device is located in the predetermined area, the GPS positioning accuracy determination means is not low in accuracy of the GPS positioning when the detected moving speed exceeds a second threshold value. The positioning device according to any one of claims 3 to 6, wherein the positioning device is determined. The GPS positioning means comprises at least two GPS receivers that perform GPS positioning at different periods,
The final positioning result calculation means selects one of the GPS receivers based on the determination result of the GPS positioning accuracy determination means, and calculates a final positioning result based on the GPS positioning result of the selected GPS receiver. The positioning device according to claim 1, wherein the positioning device calculates.   The GPS positioning means is a single GPS receiver configured to be capable of changing a GPS positioning cycle, and performs GPS positioning in the first cycle when it is determined that the accuracy of the GPS positioning is low, The positioning device according to any one of claims 1 to 7, wherein when it is determined that the accuracy of the GPS positioning is not low, the GPS positioning is performed in the second period. DR (dead reckoning) sensor,
DR positioning means for performing DR positioning based on the output of the DR sensor, and
The positioning device according to any one of claims 1 to 9, wherein the final positioning result calculation means calculates a final positioning result based on the results of the GPS positioning and the DR positioning.

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