JP2008076374A - Position-detecting device, position-detecting method, position detecting program, and navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time from turning-on of power supply to indicating of a present position. <P>SOLUTION: When a navigation system 1 is in a static state and is mounted on a cradle 4, a terrestrial magnetism value TM, position information PS, and directional information DR are stored in the system by an environmental information processing section 13; when the power supply is turned on from an operation halt to start, the system is fitted to a cradle 4; when the system in a static state and a difference between the terrestrial magnetism value TM stored in a memory section 13 and the current terrestrial magnetism value TM is less than a predetermined value, it is judged that the surrounding environment is not changed; the position information PS and the directional information DR that have been stored in the memory section 13 before the power supply is turned off, are restored as the current position information PS and the directional information DR; thus, the current position can be recognized immediately after the power supply is turned on; as a result, a map screen and a route guiding screen corresponding to the current position can be presented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection device, a position detection method, a position detection program, and a navigation device, and is suitable for application to, for example, a navigation device mounted on a vehicle.

  Conventionally, in a navigation device, a current position is calculated based on a GPS signal mounted on a moving vehicle or the like and transmitted from a GPS (Global Positioning System) satellite, and the position and traveling direction of the vehicle are indicated on a map screen. What has been made is widely spread.

  Some navigation devices have a so-called portable type that can be easily carried by a user between a vehicle and a home or between a vehicle and another vehicle.

In such a portable navigation device, a cradle that can be easily attached to and detached from the navigation device may be used. In this case, the cradle is fixedly attached to the vehicle, and the navigation device is attached to the cradle or detached from the cradle so that the vehicle can be easily attached to or detached from the vehicle (for example, , See Patent Document 1).
JP 2004-301789 A

  By the way, in such a navigation device, when calculating the current position for the first time using a GPS signal, it is necessary to perform a process of acquiring satellite orbit information, etc. until the current position is calculated and a map or the like can be displayed on the screen. It takes a few minutes to a few dozen minutes.

  However, if it takes time for the navigation device to calculate the current position in this way, it will cause the user who wants to know the position to wait immediately, so that it is still inadequate in terms of usability. .

  On the other hand, in a navigation device that is fixedly installed on a vehicle (hereinafter referred to as an installation type navigation device), when the automobile engine is started and moved, the power is turned on in conjunction with the activation of the electrical system of the automobile. While moving, the current position will continue to be calculated. In other words, in the stationary navigation apparatus, the possibility of being moved while the power is turned off is extremely low.

  By using this, the stationary navigation device stores the position information indicating the current position before the power is turned off in a nonvolatile memory or the like, and the position information stored before the power is turned off when the power is turned on. A method of setting the current position is widely used.

  However, since the portable navigation device can be carried to the user while the power is turned off, it is highly likely that the portable navigation device has been moved to a different location before the power is turned off. For this reason, the portable navigation device cannot use the method of setting the current position based on the position information stored before the power is turned off. As a result, the current position is calculated first and a map or the like is displayed on the screen. There was a problem that it took time to display.

  The present invention has been made in consideration of the above points, and intends to propose a position detection device, a position detection method, a position detection program, and a navigation device that can shorten the time until the current position can be displayed after the power is turned on. It is.

  In order to solve such a problem, in the position detection device of the present invention, a position detection unit that detects a current position based on positioning information supplied from a predetermined positioning unit and generates detection information related to the current position; and at least one A geomagnetic sensor that detects the geomagnetic value in the axial direction, the latest detection information detected by the position detection unit, a storage unit that stores the latest geomagnetic value detected by the geomagnetic sensor, and a geomagnetism when activated from an operation stop state. Based on the geomagnetism value detected by the sensor, an environmental change determination unit that determines whether or not the surrounding environment has changed compared to when the previous operation was stopped, and an ambient change from when the previous operation was stopped by the environment change determination unit An initial information setting unit is provided for setting the detection information stored in the storage unit as initial detection information when it is determined that the environment has not changed.

  Based on the comparison result between the geomagnetism value before power-off and the geomagnetism value after power-on again, the surrounding environment has not changed and it has not moved from the current position stored in the storage unit Only when it is found, the stored position information can be appropriately set as the initial position information.

  Further, in the position detection method and the position detection program of the present invention, a position detection step for detecting a current position based on positioning information supplied from a predetermined positioning means and generating detection information related to the current position, and a position detection step A storage step for storing the latest geomagnetism value detected by the geomagnetic sensor for detecting at least one axial direction geomagnetism value together with the latest detection information detected by the above in a predetermined storage unit; Based on the geomagnetic value detected by the sensor, an environmental change determination step that determines whether or not the surrounding environment has changed compared to when the previous operation was stopped, and an ambient change from when the previous operation was stopped by the environmental change determination step When it is determined that the environment has not changed, the initial detection information stored in the storage unit is set as initial detection information. It was to be provided and the distribution setting step.

  Based on the comparison result between the geomagnetism value before power-off and the geomagnetism value after power-on again, the surrounding environment has not changed and it has not moved from the current position stored in the storage unit Only when it is found, the stored position information can be appropriately set as the initial position information.

  Further, in the navigation device of the present invention, the current position is detected based on the positioning information supplied from the predetermined positioning means, and the position detection unit that generates detection information related to the current position, and the position detection unit detects the current position. Along with the latest detection information, a storage unit for storing the latest geomagnetism value detected by a geomagnetic sensor that detects at least one axis of geomagnetism value, and a geomagnetism value detected by the geomagnetic sensor when activated from an operation stop state. In addition, an environment change determination unit that determines whether or not the surrounding environment has changed compared to when the previous operation was stopped, and the environment change determination unit determines that the surrounding environment has not changed since the previous operation stop. The initial information setting unit for setting the detection information stored in the storage unit as the initial detection information, and the current information on the predetermined map based on the detection information. Location, or to be provided and a presentation unit that presents the path for extending from the current position to a predetermined destination on the map.

  Based on the comparison result between the geomagnetism value before power-off and the geomagnetism value after power-on again, the surrounding environment has not changed and it has not moved from the current position stored in the storage unit Only when it is found, the stored position information can be appropriately set as the initial position information.

  According to the present invention, based on the comparison result between the geomagnetism value before the power is turned off and the geomagnetism value after the power is turned on again, the surrounding environment is not changed and the current position stored in the storage unit is moved. Only when it is determined that the current position has not been detected, the stored position information can be appropriately set as the initial position information. Thus, position detection can shorten the time until the current position can be displayed immediately after the power is turned on. A device, a position detection method, a position detection program, and a navigation device can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Navigation Device (1-1) Appearance Configuration In FIG. 1, the navigation device 1 calculates a current position based on a GPS signal from a GPS satellite (not shown) by a GPS antenna 2 and displays a display unit. By displaying a map screen, a route guidance screen to a desired destination, and the like on 3, the user can be presented with a current position, a surrounding map, a guidance route, and the like.

  The navigation device 1 is configured to be portable so that it can be easily carried by a user, and is assumed to be used in the user's home or in the vehicle cabin.

  The navigation device 1 can be easily mounted on the dedicated cradle 4 and can be easily detached from the cradle 4. In practice, the cradle 4 is mounted in advance on a dashboard or the like in the vehicle interior of the vehicle, so that the navigation device 1 can be easily mounted on or removed from the vehicle.

  Further, the cradle 4 is attached to a dashboard or the like in the vehicle interior by a suction cup (not shown), and like the navigation device 1, it can be easily attached to or removed from the vehicle. Has been made.

  By the way, the GPS antenna 2 is installed under the windshield, etc., so that it can receive GPS signals from GPS satellites that orbit the satellites in the sky without being blocked by the body of the vehicle. Has been made.

(1-2) Circuit Configuration of Navigation Device As shown in FIG. 2, the navigation device 1 cannot receive a GPS signal, a GPS processing unit 10 that performs a GPS signal reception process in addition to the display unit 3 described above. The navigation unit 12 generates display data representing a route guidance screen or the like based on information from the autonomous speed calculation unit 11, the GPS processing unit 10 or the autonomous speed calculation unit 11 that calculates a speed based on detection values from various sensors. And a storage unit 13 for storing various data.

  The GPS processing unit 10 receives GPS signals from a plurality of GPS satellites (not shown) via the GPS antenna 2, and generates position information PS by performing predetermined position calculation processing based on the GPS signals. This is supplied to the autonomous speed calculation unit 11, the navigation unit 12, and the like.

  In response to this, the navigation unit 12 reads map data in a range corresponding to the position information PS from a predetermined map storage unit (not shown), and superimposes a mark or the like indicating the current position on the map data. Data is generated and sent to the display unit 3 to display a display screen.

  On the other hand, when the GPS signal cannot be received by the GPS antenna 2 such as behind a building or in a tunnel, the navigation unit 12 cannot calculate the current position of the vehicle because the position information PS is not supplied.

  At this time, the autonomous speed calculation unit 11 calculates the speed V and the horizontal angular speed φ of the vehicle as information for estimating the current position of the vehicle.

  The autonomous speed calculation unit 11 includes an acceleration sensor 14 that detects acceleration acting in the traveling direction of the vehicle, an atmospheric pressure sensor 15 that detects ambient atmospheric pressure, and a gyro sensor 16 that detects a rotational angular velocity about the vertical direction of the vehicle. And are connected.

  The acceleration sensor 14 generates an acceleration detection signal SA according to the acceleration acting in the traveling direction of the vehicle, and supplies it to the autonomous speed calculation unit 11.

  The atmospheric pressure sensor 15 generates an atmospheric pressure detection signal SR according to the ambient atmospheric pressure and supplies it to the autonomous speed calculation unit 11.

  The gyro sensor 16 detects an angular velocity φ around the vertical direction (that is, around the yaw rotation axis) in the vehicle, and supplies this to the autonomous velocity calculation unit 11.

  The autonomous speed calculation unit 11 is configured around a CPU (Central Processing Unit) (not shown), and reads and executes various application programs such as a speed calculation program from a ROM (Read Only Memory) (not shown). .

  Thereby, the autonomous speed calculation unit 11 converts the acceleration detection signal SA into the detected acceleration αG acting in the traveling direction of the vehicle and then calculates the speed V, and the atmospheric pressure detection signal SR represents the atmospheric pressure representing the ambient atmospheric pressure. An altitude change amount calculation unit 21 that calculates an altitude change amount in a predetermined period after being converted to PR, an angular velocity correction unit 22 that calculates a corrected angular velocity φc by performing a predetermined correction process on the angular velocity φ, and the navigation apparatus 1 Each processing function such as a stationary determination unit 23 that determines whether or not the vehicle is stationary, that is, whether the vehicle is stopped or traveling (details will be described later).

  Incidentally, the autonomous speed calculation unit 11 stores the speed V, the corrected angular speed φc, and the like in the storage unit 13 formed of a nonvolatile memory, and reads it out as necessary.

  The autonomous speed calculation unit 11 can determine whether or not the vehicle is stationary based on the acceleration detection signal SA in the stationary determination unit 23.

  The autonomous speed calculation unit 11 sends the speed V and the corrected angular speed φc calculated in this way to the navigation unit 12. In response to this, the navigation unit 12 estimates the current position of the new vehicle based on the speed V, the corrected angular speed φc, the previous position information PS, and the like, and uses the new position information PS as the new position information PS. A display screen corresponding to the information PS is displayed on the display unit 3.

  Further, the navigation unit 12 sends the direction information DR indicating the traveling direction at this time together with the latest position information PS to the storage unit 13 to store and update the position information PS and the direction information DR. Yes.

  Incidentally, unlike the so-called stationary navigation device, the navigation device 1 does not use a vehicle speed pulse signal that is generated in the vehicle and whose period changes in accordance with the speed of the vehicle. Wiring processing when attaching to the vehicle can be simplified.

  As described above, when the GPS device 2 cannot receive the GPS signal, the navigation device 1 calculates the velocity V and the corrected angular velocity φc based on the acceleration detection signal SA, the atmospheric pressure detection signal SR, and the angular velocity φ by the autonomous velocity calculation unit 11. The navigation unit 12 can calculate the current position using these.

(2) Calculation of Speed V and Correction Angular Speed φc Next, calculation of the speed V and correction angular speed φc by the autonomous speed calculation unit 11 when the navigation device 1 cannot receive a sufficient GPS signal by the GPS antenna 2 will be described. To do.

(2-1) Calculation of Speed First, calculation of the speed V in the autonomous speed calculation unit 11 will be described. Here, as shown in FIG. 3A, it is assumed that the vehicle 100 is traveling on a slope SL having a gradient angle θ with respect to the horizontal plane HZ.

  In this case, the detected acceleration αG obtained based on the acceleration detection signal SA detected by the acceleration sensor 14 (FIG. 2) includes the original acceleration resulting from the movement of the vehicle 100 (hereinafter referred to as the vehicle acceleration αP). And a traveling direction component of the gravitational acceleration g acting on the vehicle 100 (hereinafter referred to as a gravitational acceleration component gf). That is, the gravitational acceleration component gf can be calculated as the following equation (1) based on the difference between the detected acceleration αG and the vehicle acceleration αP.

  The autonomous speed calculation unit 11 (FIG. 2) of the navigation device 1 can calculate the vehicle acceleration αP after calculating the distance and speed based on a plurality of position information PS at a plurality of times.

  By the way, as shown in FIGS. 3B and 3C, the vehicle 100 is inclined SL during a measurement time mt (for example, about 1 second) from a certain time t0 as a measurement start time to a time t1 as a measurement end time. The ratio (that is, sin θ) between the distance Dm that travels through the vehicle and the altitude change amount Dh of the vehicle 100 at the measurement time mt is equal to the ratio between the gravitational acceleration component gf and the gravitational acceleration g (that is, sin θ). Therefore, the following relationship (2) is established.

  The distance Dm can be expressed as the following equation (3) by using the speed V0 of the vehicle 100 and the vehicle acceleration αP at time t0 according to a general formula using the speed and acceleration related to the distance.

  When the formula (2) is modified and the formulas (1) and (3) are substituted, the following formula (4) is obtained.

  When this equation (4) is arranged for the vehicle acceleration αP, the following equation (5) is obtained.

  Here, the speed V1 at the time t1 is in accordance with a general physical formula relating to the speed V, and the relationship of the following expression (6) is established.

  This equation (6) represents that the speed V1 can be calculated based on the speed V0. Here, the following equation (7) can be obtained by substituting the equation (5) into the equation (6).

  That is, if the autonomous speed calculation unit 11 can obtain the altitude change amount Dh, the speed calculation unit 20 uses the detected acceleration αG, the measurement time mt, the speed V0 at the time t0, the gravitational acceleration g, and the altitude change amount Dh. Thus, the speed V1 at time t1 can be calculated according to the equation (7).

(2-2) Calculation of altitude change amount Next, the altitude change amount Dh calculation processing in the autonomous speed calculation unit 11 (FIG. 1) will be described. When the GPS antenna 2 cannot receive a GPS signal, the autonomous speed calculation unit 11 uses the fact that there is generally a correspondence between the atmospheric pressure PR and the altitude h, and uses the atmospheric pressure detection signal SR acquired from the atmospheric pressure sensor 15 as the atmospheric pressure PR. The altitude h is calculated from the atmospheric pressure PR.

  Actually, the autonomous speed calculation unit 11 stores in the storage unit 13 a pressure altitude correspondence table TBL in which correspondences between general atmospheric pressure and altitude are tabulated in advance, and the pressure PR0 at time t0 and the pressure PR1 at time t1. Based on the above, altitudes h0 and h1 corresponding to the atmospheric pressures PR0 and PR1 are read from the atmospheric pressure altitude correspondence table TBL, respectively.

  Subsequently, the autonomous speed calculation unit 11 uses the altitude change amount calculation unit 21 to show the altitude change amount Dh that is the difference between the altitude h0 of the vehicle 100 at time t0 and the altitude h1 of the vehicle 100 at time t1 (8 ) Calculate according to the formula.

  By the way, the atmospheric pressure generally has different values depending on the altitude, and even at the same altitude, it slowly changes due to the influence of the weather such as low pressure and high pressure. However, the measurement time mt (about 1 second), which is the time difference when the speed detection unit 2 detects the atmospheric pressures PR0 and PR1, is sufficiently shorter than the time during which significant atmospheric pressure fluctuations occur due to the influence of the weather. It can be considered that the altitude change amount Dh as a relative difference has no influence on the atmospheric pressure due to weather or the like.

  Therefore, the autonomous speed calculation unit 11 can obtain the altitude change amount Dh with high reliability from the atmospheric pressure altitude correspondence table TBL and the equation (8). The altitude change amount Dh calculated in this way is expressed by the equation (7). Can be applied.

  In this case, since the autonomous speed calculation unit 11 cannot calculate the accurate vehicle acceleration αP, it cannot directly calculate the traveling direction component gf included in the detected acceleration αG due to the relationship of the equation (1). Since the traveling direction component gf can be canceled out by the altitude change amount Dh using the relationship shown in the expression (2), as a result, the speed is accurately calculated by the expression (7) regardless of the traveling direction component gf. V can be calculated.

(2-3) Correction of Angular Velocity Next, correction processing for correcting the angular velocity φ supplied from the gyro sensor 16 and calculating the corrected angular velocity φc will be described. Here, as shown in FIG. 4A corresponding to FIG. 3A, it is assumed that the vehicle 100 is traveling on a slope SL having a gradient angle θ with respect to the horizontal plane HZ toward the traveling direction FW. .

  At this time, the angular velocity φ detected by the gyro sensor 16 represents a rotational angular velocity about the virtual yaw rotation axis YA of the vehicle 100 on the slope SL, as shown in FIG. 4B. However, since the vehicle 100 is traveling on the slope SL, the angular velocity φ detected by the gyro sensor 16 is a value obtained by multiplying the actual rotational angular velocity of the vehicle 100 by cos θ.

  Therefore, the angular velocity correction unit 22 (FIG. 2) of the autonomous velocity calculation unit 11 moves the distance Dm obtained based on the altitude change Dh calculated according to the equation (8) and the velocity V calculated according to the equation (7). Then, sin θ is calculated using the following equation (9). Incidentally, this equation (9) is derived from the relationship shown in FIG.

  Next, the angular velocity correction unit 22 calculates cos θ by applying sin θ obtained from the equation (9) to the equation (10) that is a general trigonometric property.

  Further, the angular velocity correction unit 22 calculates a corrected angular velocity φc (FIG. 4B) based on cos θ and the angular velocity φ according to the following equation (11).

  Thereafter, the autonomous speed calculation unit 11 sends the corrected angular speed φc to the navigation unit 12 together with the speed V calculated based on the equation (7).

  In response to this, when the GPS unit 2 cannot receive the GPS signal and the position information PS cannot be acquired from the GPS processing unit 10, the navigation unit 12 uses the speed V and the corrected angular speed φc together with the previous position information PS. A so-called dead reckoning (dead reckoning navigation) for calculating an estimated position of the vehicle 100 is performed.

  At this time, even if the vehicle 100 is traveling on the slope SL and the angular velocity φ detected by the gyro sensor 16 is different from the original angular velocity of the vehicle 100, the navigation unit 12 is not the angular velocity φ but the slope of the slope SL. By using the corrected angular velocity φc corrected according to the angle θ, the position information PS of the vehicle 100 can be estimated with high accuracy.

  Thereby, even if the navigation apparatus 1 cannot receive the GPS signal and cannot recognize the accurate current position based on the position information PS, the navigation apparatus 1 is based on the position information PS estimated with high accuracy based on the velocity V and the corrected angular velocity φc. In addition, the current position of the vehicle 100 can be displayed on the map of the display screen to be visually recognized by the user.

(2-4) Determination of stationary state When the autonomous speed calculation unit 11 cannot receive a GPS signal, as shown in the equation (6), the speed V0 at time t0 (that is, immediately before) is used at time t1. In order to calculate the (that is, current) speed V1, if the speed V0 is incorrect, the speed V1 also has an incorrect value. For this reason, the autonomous speed calculation unit 11 needs to reliably detect the initial speed V in the navigation device 1 attached to the vehicle 100, that is, the speed V in a stationary state as “zero”.

  In general, when the vehicle 100 is traveling, the acceleration detection signal SA constantly fluctuates in accordance with the shape of the road, traffic conditions, and the like. Therefore, the acceleration detection signal SA can continue to be a constant value. Therefore, the acceleration detection signal SA has a certain degree of variation. On the contrary, when the vehicle 100 is stopped, the acceleration detection signal SA does not fluctuate from zero and becomes a constant value, and even if the engine vibration or detection error during idling is taken into consideration, the acceleration detection signal SA The variation is within a predetermined range.

  Therefore, the autonomous speed calculation unit 11 calculates the variance SAvar of the acceleration detection signal SA in a predetermined time range (for example, 1 second) by the stillness determination unit 23 (FIG. 2), and if the variance SAvar is within the predetermined range. It is determined that the vehicle 100 is stopped and the navigation apparatus 1 is stationary, and the speed V at this time is corrected to zero.

  Thereby, the autonomous speed calculation unit 11 can correctly determine whether the navigation device 1 attached to the vehicle 100 is in the moving state or the stationary state, and corrects the speed V to zero when the navigation device 1 is in the stationary state. By doing so, the subsequent speed V can be calculated correctly.

(2-5) Speed Output Processing Next, the speed output processing procedure when the autonomous speed calculation unit 11 calculates the speed V of the vehicle 100 and outputs it to the navigation unit 12 will be described using the flowchart of FIG.

  When the navigation apparatus 1 is powered on, the autonomous speed calculation unit 11 starts the speed output processing procedure RT1 and proceeds to step SP1. In step SP1, the autonomous speed calculation unit 11 distributes the acceleration detection signal SA calculated in the past 1 second by the stationary determination unit 23 to determine whether or not the navigation device 1 attached to the vehicle 100 is in a stationary state. SAvar is calculated, and the process proceeds to the next step SP2.

  In step SP2, the autonomous speed calculation unit 11 determines whether or not the variance SAvar of the acceleration detection signal SA calculated in step SP1 is less than a predetermined threshold by the stationary determination unit 23. If a positive result is obtained here, this means that the possibility that the navigation device 1 is in a stationary state is very high because the distributed SAvar is relatively small, and at this time, the autonomous speed calculation unit 11 Moves to the next step SP3.

  In step SP3, the autonomous speed calculation unit 11 corrects the immediately preceding speed V0 stored in the storage unit 13 to zero, and proceeds to the next step SP4.

  On the other hand, if a negative result is obtained in step SP2, this indicates that there is a high possibility that the navigation device 1 attached to the vehicle 100 is in a moving state because the variance SAvar of the acceleration detection signal SA is somewhat large. At this time, the autonomous speed calculation unit 11 proceeds to the next step SP4 without particularly correcting the immediately preceding speed V0.

  In step SP4, the autonomous speed calculation unit 11 determines whether or not the position information PS can be acquired from the GPS processing unit 10. If an affirmative result is obtained here, this indicates that the velocity V can be calculated based on the position information PS acquired from the GPS processing unit 10, and at this time, the arithmetic processing block 10 proceeds to the next step SP5.

  In step SP5, the autonomous speed calculation unit 11 stores the detected acceleration αG, the atmospheric pressure PR, and the position information PS in the storage unit 13 in association with the time at this time, and proceeds to the next step SP7.

  On the other hand, if a negative result is obtained in step SP4, this indicates that the position information PS cannot be obtained from the GPS processing unit 10, and therefore it is necessary to calculate the velocity V without using the position information PS. Then, the autonomous speed calculation unit 11 proceeds to the next subroutine SRT1.

  In the subroutine SRT1, the autonomous speed calculation unit 11 calculates the current speed V (speed V1) according to the above-described equation (7) by the speed calculation unit 20 (details will be described later), and proceeds to the next step SP6.

  In step SP6, the autonomous speed calculation unit 11 sends the speed V and the corrected angular speed φc to the navigation unit 12, and proceeds to the next step SP7.

  In step SP7, the autonomous speed calculation unit 11 waits until the measurement time mt elapses, and then returns to step SP1 again to repeat a series of processes.

  As described above, when the position information PS cannot be acquired from the GPS processing unit 10, the autonomous speed calculation unit 11 calculates the speed V and the correction angular speed φc and sends them to the navigation unit 12.

  Next, the speed calculation subroutine SRT1 will be described with reference to the flowchart of FIG. Here, the current time is set as time t1, and the time before the measurement time mt is set as time t0.

  In response to the call from the speed output processing procedure RT1 (FIG. 5), the autonomous speed calculation unit 11 starts the speed calculation subroutine SRT1 shown in FIG. 6 and proceeds to step SP11. In step SP11, the autonomous speed calculation unit 11 acquires the detected acceleration αG1 at the current time t1 from the acceleration sensor 14 and the atmospheric pressure PR1 from the atmospheric pressure sensor 15, and proceeds to the next step SP12.

  In step SP12, the autonomous speed calculation unit 11 reads the detected acceleration αG0, the atmospheric pressure PR0, and the speed V0 at time t0 stored in advance in the storage unit 13, and proceeds to the next step SP13.

  In step SP13, the autonomous speed calculation unit 11 reads the altitudes h0 and h1 corresponding to the atmospheric pressures PR0 and PR1 from the atmospheric pressure altitude correspondence table TBL stored in the storage unit 13, and calculates the altitude change amount Dh according to the equation (8). Then, the process proceeds to the next step SP14.

  In step SP14, the autonomous speed calculation unit 11 calculates the speed V1 at the current time t1 using the altitude change amount Dh, the measurement time mt, and the gravitational acceleration g together with the detected acceleration αG0 and the speed V0 at the time t0 according to the equation (7). Then, the process proceeds to the next step SP15.

  In step SP15, the autonomous speed calculation unit 11 stores the detected acceleration αG1, the atmospheric pressure PR1 and the speed V1 at the current time t1 in the storage unit 13 for calculating the next speed V, and proceeds to the next step SP16.

  In step SP16, the autonomous speed calculation unit 11 uses the altitude change amount Dh calculated in step SP13 and the travel distance Dm obtained based on the speed V calculated in step SP14 to calculate sin θ according to equation (9). Based on this, cos θ is calculated according to the equation (10), and the process proceeds to the next step SP17.

  In step SP17, the autonomous speed calculation unit 11 calculates a corrected angular speed φc obtained by correcting the angular speed φ in accordance with the equation (11), moves to the next step SP18, ends the speed calculation subroutine SRT1, and returns to the original speed output processing procedure RT1. Return to FIG.

  As described above, the autonomous speed calculation unit 11 calculates the detected acceleration αG, the atmospheric pressure PR, and the speed V and stores them in the storage unit 13 and calculates the corrected angular speed φc.

(3) Position setting at power-on (3-1) Determination of environmental change by geomagnetic sensor The navigation device 1 (FIG. 1) is provided with a geomagnetic sensor 17 that can detect geomagnetism in three axial directions.

  The geomagnetic sensor 17 originally detects the geomagnetism in order to acquire the azimuth angle in the installed state, and outputs it as a three-dimensional geomagnetic vector (hereinafter, the value output at this time is the geomagnetic value). Called).

  Here, if the geomagnetic sensor 17 is fixed to the vehicle 100, it is considered that the possibility that the azimuths of the vehicle 100 completely coincide before and after the vehicle 100 moves is extremely low. For this reason, when the vehicle 100 moves, the geomagnetism value detected by the geomagnetic sensor 17 changes.

  By the way, the geomagnetic sensor 17 has a property that when a large metal body such as a magnet mounted on a speaker or the body of the vehicle 100 exists in the surroundings, the magnetic influence due to the leakage magnetic field or the geomagnetism due to the metal body. It becomes difficult to detect a geomagnetism value representing a correct azimuth angle due to the interruption of.

  In particular, in the vehicle interior of the vehicle 100, since the periphery is surrounded by the body of the vehicle 100, the geomagnetic sensor 17 outputs a geomagnetic value that is greatly influenced by the body of the vehicle 100.

  Here, an environment in which an object that affects geomagnetic detection is present around the geomagnetic sensor 17 (hereinafter referred to as an ambient environment) will be considered.

  For example, since the presence or absence of the body of the vehicle 100 is different between the interior of the vehicle 100 and a general outdoor, the geomagnetic sensor 17 has different geomagnetic values in the surrounding environment even if it is installed to face the same direction. Expected to output. Similarly, the geomagnetic sensor 17 is expected to detect different geomagnetic values in the surrounding environment of the vehicle 100 and in the home.

  Thus, the geomagnetic sensor 17 has the property of detecting different geomagnetic values depending not only on the direction of installation but also on the surrounding environment.

  By the way, the navigation device 1 is mounted on, for example, the cradle 4 attached to the vehicle 100, and after the power is turned on and the map display processing is performed, when the user gets off the vehicle 100, the power is turned off and is removed from the cradle 4. Can be carried around. In addition, the cradle 4 may be removed from the vehicle 100 together with the navigation device 1 and carried.

  For this reason, the navigation device 1 may be attached to the cradle 4 in the original vehicle 100 when the power is turned on next time. There is also a possibility that it is held by a user's hand without being mounted or placed on a tabletop or the like.

  Therefore, the navigation device 1 is attached to the same vehicle 100 as before the power is turned off and the vehicle 100 is moved if the geomagnetism value is substantially equal to that before the power is turned off. In other words, it is determined that the vehicle 100 and the navigation device 1 are installed at the same position and in the same direction as before the power is turned off.

  In this case, the navigation device 1 uses the geomagnetic value as an index to determine whether or not the surrounding environment has changed between before power-off and after power-on again.

  Further, in order for the navigation device 1 to be installed in the same position and in the same direction as before the power is turned off, the navigation device 1 is mounted on the cradle 4 and has the same relative position with respect to the vehicle 100, and the vehicle 100 and It is necessary that the navigation device 1 is not moving, at least in a stationary state.

  Therefore, the navigation device 1 is turned off under the condition that the geomagnetism value is substantially the same before the power is turned off and after the power is turned on again, as long as the navigation device 1 is attached to the cradle 4 and is stationary. It is determined that it is installed in the same position and in the same direction as before.

(3-2) Circuit Configuration of Navigation Device Specifically, in the navigation device 1 (FIG. 2), the environment change determination unit 31 of the environment information processing unit 30 has the same ambient environment before power-off and after power-on. Whether or not is determined.

  The environment information processing unit 30 is mainly configured by a CPU (not shown), reads an environment information storage program, a detection information restoration program, and the like from a ROM (not shown), and uses a RAM (not shown) as a work piece. By executing as an area, environment information storage processing, detection information restoration processing, and the like (details will be described later) are performed.

  The geomagnetic sensor 17 detects a geomagnetic value TM in which the influence of the surrounding environment is included in the original geomagnetism, and supplies this to the environment change determination unit 31 of the environment information processing unit 30.

  The cradle attachment / detachment detection unit 18 detects whether or not the navigation apparatus 1 is attached to the cradle 4 and supplies the attachment / detachment information CD to the environment change determination unit 31 as a detection result.

  In addition to the geomagnetic value TM and the attachment / detachment information CD, the environment change determination unit 31 acquires the stationary information ST from the stationary determination unit 23 and the position information PS from the GPS processing unit 10.

  In practice, the environment change determination unit 31 recognizes that the navigation device 1 is attached to the cradle 4 based on the attachment / detachment information CD during operation, and the vehicle 100 is stopped (that is, the navigation device 1 is in contact with the ground). The navigation device 1 may be turned off, and the geomagnetic value TM is used as information representing the surrounding environment at this time (hereinafter referred to as environment information). It is stored in the storage unit 13 or updated.

  Incidentally, the environment change determination unit 31 is based on the temporal change of the position information PS when the position information PS is supplied from the GPS processing unit 10, and based on the stationary information ST when the position information PS is not supplied. It is determined whether or not the navigation device 1 is stationary.

  Further, as described above, the navigation unit 12 causes the storage unit 13 to store the position information PS and the direction information DR as information indicating the latest position detection state in the navigation device 1 (hereinafter referred to as detection information), Or it is made to update.

  Thereafter, the environment change determination unit 31 of the environment information processing unit 30 acquires the geomagnetic value TM, the attachment / detachment information CD, and the stationary information ST when the navigation apparatus 1 is turned off and then turned on again.

  At this time, as described above, the GPS processing unit 10 cannot output the position information PS because it takes time to calculate the first current position immediately after the navigation apparatus 1 is turned on.

  Therefore, when the environment change determination unit 31 recognizes that the navigation device 1 is mounted on the cradle 4 and is stationary with the vehicle 100 based on the attachment / detachment information CD, the past geomagnetic value TM stored in the storage unit 13 and the current value are stored. If the error between the two is less than a predetermined threshold value, it is determined that the surrounding environment is not changed and is the same.

  This is because the previous position information PS and direction information DR stored in the storage unit 13 before the power is turned off are estimated because the position and direction of the navigation device 1 are estimated to be the same before and after the power is turned off. This indicates that the current position information PS and direction information DR can be considered.

  At this time, the initial information setting unit 32 of the environment information processing unit 30 reads the past position information PS and the direction information DR from the storage unit 13 according to the determination result from the environment change determination unit 31, and these are read as current position information, respectively. PS and direction information DR are supplied to the navigation unit 12 and the autonomous speed calculation unit 11.

  In other words, at this time, the initial information setting unit 32 of the environment information processing unit 30 reads the detection information of the navigation device 1 before the power is turned off and restores it as the current detection information.

  Accordingly, the navigation unit 12 can acquire the position information PS indicating the current position and the direction information DR indicating the traveling direction even before the process of calculating the first current position by the GPS processing unit 10 is completed. Therefore, a map screen, a route guidance screen, and the like corresponding to the current position and the traveling direction can be immediately displayed on the display unit 3 without causing the user to wait.

  On the other hand, the environment change determination unit 31 stores the information in the storage unit 13 when it is recognized that the navigation device 1 is not attached to the cradle 4 or is not stationary by the attachment / detachment information CD immediately after the power is turned on. If the error between the past geomagnetic value TM and the current geomagnetic value TM is greater than or equal to a predetermined threshold value, it is determined that the surrounding environment has changed.

  At this time, the initial information setting unit 32 determines that the detection information should not be restored, and the process of calculating the first current position by the GPS processing unit 10 is completed without restoring the position information PS and the direction information DR. It waits for the position information PS to be output.

  As described above, the navigation device 1 is attached to the cradle 4 when the power is turned on and is stationary with the vehicle 100, and an error between the geomagnetic value TM before the power is turned off and the current geomagnetic value TM is a predetermined value. When it is less than the threshold, it is determined that the surrounding environment is the same, and the map information, route guidance, and the like can be immediately performed by restoring the detection information before the power is turned off.

(4) Processing Procedure Next, the environment information storage processing procedure RT2 for storing the geomagnetic value TM as the environment information in the storage unit 13 during operation by the environment information processing unit 30 in the navigation device 1, and the environment information at the time of activation The detection information restoration processing procedure RT3 when restoring the position information PS and the direction information DR as detection information according to the above will be described with reference to the flowcharts of FIGS.

  Incidentally, the position information PS and the direction information DR as detection information are stored and updated in the storage unit 13 as needed by the navigation unit 12. For this reason, the environment information processing unit 30 does not dare to store or update the detection information.

(4-1) Environmental Information Storage Processing In practice, the environmental information processing unit 30 is configured to execute the environmental information storage processing procedure RT2 (FIG. 7) at predetermined time intervals while the power is turned on. When the environment information storage processing procedure RT2 is started, the process proceeds to step SP21.

  In step SP <b> 21, the environment information processing unit 30 determines whether the navigation device 1 is attached to the cradle 4. If a negative result is obtained here, this means that the navigation device 1 is not fixed and the possibility of being installed in the same position and in the same direction before and after the power-off is very low. The information processing section 30 moves to next step SP27.

  On the other hand, if a positive result is obtained in step SP21, this indicates that there is a high possibility that the navigation device 1 is fixed to the vehicle 100 via the cradle 4. At this time, the environment information processing unit 30 Control goes to step SP22.

  In step SP22, the environment information processing unit 30 determines whether or not the position information PS can be acquired from the GPS processing unit 10. If a positive result is obtained here, the environmental information processing unit 30 proceeds to the next step SP23.

  In step SP23, the environment information processing unit 30 calculates the velocity V based on the temporal change of the position information PS, and proceeds to the next step SP24.

  In step SP24, the environment information processing unit 30 determines whether or not the speed V is less than a predetermined stillness determination threshold value. If a positive result is obtained here, this indicates that there is a high possibility that the navigation apparatus 1 is stationary together with the vehicle 100. At this time, the environment information processing unit 30 moves to the next step SP26.

  On the other hand, if a negative result is obtained in step SP24, this indicates that there is a high possibility that the navigation apparatus 1 is moving together with the vehicle 100, and the environment information processing unit 30 proceeds to the next step SP27.

  On the other hand, if a negative result is obtained in step SP22, this indicates that the velocity V cannot be calculated from the position information PS. At this time, the environment information processing unit 30 performs the autonomous velocity calculation unit 11. In order to determine whether or not the navigation device 1 is in a stationary state based on the speed V calculated in step, the process proceeds to the next step SP25.

  In step SP25, the environment information processing unit 30 determines whether or not the navigation device 1 is in a stationary state based on the stationary information ST from the stationary determination unit 23 (FIG. 2). If a positive result is obtained here, the environmental information processing unit 30 proceeds to the next step SP26.

  In step SP <b> 26, the environment information processing unit 30 is likely to be stationary with the vehicle 100, so the navigation device 1 is powered off by the user and removed from the cradle 4, or the cradle 4 and the vehicle 100 together. The geomagnetic value TM as the environment information at this time is stored in the storage unit 13 in consideration of the possibility of being taken out from the environment, and then the process proceeds to the next step SP28 to end the environment information storage processing procedure RT2.

  On the other hand, if a negative result is obtained in step SP25, it is highly possible that the navigation apparatus 1 is moving together with the vehicle 100, and the environment information processing unit 30 moves to the next step SP27.

  In step SP27, the environmental information processing unit 30 obtains the geomagnetic value TM stored in the storage unit 13 at this time because at least the navigation device 1 is not mounted on the cradle 4 or the vehicle 100 is in a traveling state. Since the geomagnetic value TM has been deleted from the storage unit 13, the environment information storage processing procedure RT2 is terminated after moving to the next step SP28.

(4-2) Detection Information Restoration Process When the environment information processing unit 30 is started from the operation stop state in which the power is turned off, it tries to restore the detection information according to the environment information at that time. The detection information restoration processing procedure RT3 (FIG. 8) is started, and the process proceeds to step SP31.

  In step SP31, the environment information processing unit 30 determines whether or not the navigation device 1 is mounted on the cradle 4. If a negative result is obtained here, this means that at least the navigation device 1 is not fixed to the vehicle 100 and is in a different position from when the environment information (that is, the geomagnetic value TM) is stored before the power is turned off. This indicates that the possibility of being installed is extremely high. At this time, the environment information processing unit 30 proceeds to the next step SP36.

  On the other hand, if a positive result is obtained in step SP31, this indicates that there is a high possibility that the navigation device 1 is fixed to the vehicle 100 via the cradle 4. At this time, the environment information processing unit 30 performs the following operation. Control goes to step SP32.

  In step SP32, the environment information processing unit 30 determines whether or not the geomagnetic value TM is stored in the storage unit 13. If a negative result is obtained here, this means that the geomagnetic value TM has not been stored before the power is turned off, and at this time, the environment information processing unit 30 proceeds to the next step SP36.

  On the other hand, if an affirmative result is obtained in step SP32, this indicates that a change in the surrounding environment can be determined based on the geomagnetic value TM stored in the storage unit 13, and at this time, the environment information processing unit 30 Moves to the next step SP33.

  In step SP33, the environment information processing unit 30 determines whether or not the navigation device 1 is in a stationary state based on the stationary information ST from the stationary determination unit 23 (FIG. 2). If a negative result is obtained here, this means that the navigation device 1 has moved together with the vehicle 100 from the position where the geomagnetic value TM was stored before the power was turned off, so that the surrounding environment is definitely different from that before the power was turned off. At this time, the environment information processing unit 30 proceeds to the next step SP36.

  On the other hand, if a positive result is obtained in step SP33, this indicates that the vehicle 100 may not have moved from the position where the geomagnetic value TM was stored before the navigation apparatus 1 was turned off. The environment information processing unit 30 moves to next step SP34.

  In step SP34, the environmental information processing unit 30 calculates a difference between the geomagnetic value TM before power-off stored in the storage unit 13 and the current geomagnetic value TM, and whether or not the difference is less than a predetermined threshold value. Determine whether. If a positive result is obtained here, this means that the geomagnetic value TM as the environmental information is almost the same before and after the power is turned off, so that the surrounding environment is not changed and can be regarded as the same. At this time, the environment information processing unit 30 proceeds to the next step SP35.

  In step SP35, the environment information processing unit 30 restores the position information PS and the direction information DR stored in the storage unit 13 as detection information by using the current position information PS and the direction information DR, and the position information PS and After sending the direction information DR to the navigation unit 12, the process proceeds to the next step SP37, and the detection information restoration processing procedure RT3 is completed.

  On the other hand, if a negative result is obtained in step SP34, this indicates that the geomagnetic value TM does not match between before and after the power is turned off, so there is a high possibility that the surrounding environment has changed. Represents that there is a possibility of stopping at a different position. At this time, the environment information processing section 30 proceeds to the next step SP36.

  In step SP36, if the environment information processing unit 30 stores the geomagnetic value TM in the storage unit 13, the environment information processing unit 30 deletes the geomagnetic value TM because there is a high possibility that the surrounding environment of the navigation device 1 has already changed. Then, the process proceeds to the next step SP37, and the detection information restoration processing procedure RT3 is terminated.

(5) Operation and Effect In the above configuration, the navigation device 1 is set as environmental information when the environment information processing unit 30 is in a stationary state before the power is turned off and the navigation device 1 is mounted on the cradle 4. The geomagnetic value TM is stored, and the navigation unit 12 stores and updates the position information PS and the direction information DR as detection information in the storage unit 13 as needed.

  After that, the navigation device 1 acquires the geomagnetic value TM, the attachment / detachment information CD, and the stationary information ST at this time from the environment information processing unit 30 when the power is turned on and started from the operation stop state. Here, the environmental information processing unit 30 is such that the navigation device 1 is mounted on the cradle 4 and is stationary, and the difference between the geomagnetic value TM stored in the storage unit 13 as environmental information and the current geomagnetic value TM is predetermined. If it is less than the threshold value, it is determined that the surrounding environment has not changed, and the position information PS and the direction information DR before power-off stored in the storage unit 13 are set as the current position information PS and the direction information DR. Thus, the detection information is restored.

  Therefore, the navigation device 1 can detect changes in the surrounding environment using the geomagnetic value TM, and can appropriately restore the position information PS and the direction information DR as detection information, so that the surrounding environment has changed. If not, the current position can be recognized immediately after the power is turned on, and a map screen, a route guidance screen, or the like corresponding to the current position can be presented.

  At this time, the environment information processing unit 30 of the navigation device 1 detects changes in the surrounding environment using the geomagnetic values TM in the three-axis directions detected by the geomagnetic sensor 17, so that the vehicle 100 attached via the cradle 4 is Whether or not the navigation device 1 is installed in the vehicle 100 along with the change in direction, and further, the arrangement state of a large metal body around the navigation device 1, that is, the type (shape) of the vehicle 100 and the navigation device in the passenger compartment. A change in the installation position of 1 can also be detected.

  As a result, the environment information processing unit 30 of the navigation device 1 has the navigation device 1 installed in the same position and in the same direction in the same vehicle 100 as compared with before the power is turned off. It is possible to detect whether the vehicle is stopped in the same direction, that is, whether the vehicle 100 has been moved.

  In other words, the navigation apparatus 1 can take over the detection information only when the cradle 4 is attached and the vehicle 100 is not moved before and after the power is turned off.

  Moreover, since the navigation apparatus 1 can detect the geomagnetic value TM in the triaxial direction by the geomagnetic sensor 17, the environment information processing unit 30 can change the surrounding environment compared to the case of using the biaxial geomagnetic sensor. It can be detected with high accuracy.

  On the other hand, the environment information processing unit 30 of the navigation device 1 is not connected to the cradle 4, moved (that is, the vehicle 100 is moved), or before and after the power is turned off. When the geomagnetic value TM is different, it can be determined that the position and / or direction of the navigation device 1 is different from that before the power is turned off, so that the position information PS is not restored by mistake, It is possible to prevent erroneous recognition of the current position.

  According to the above configuration, the navigation apparatus 1 is in a stationary state together with the vehicle 100 before the power is turned off, and when the navigation apparatus 1 is mounted on the cradle 4, the environment information processing unit 30 sets the environment information as the environment information. The geomagnetic value TM, the position information PS as the detection information, and the direction information DR are stored in the storage unit 13, and when the power is turned on and started from the operation stop state, the geomagnetic value TM is attached to the cradle 4 and is in a stationary state and stored. If the difference between the geomagnetic value TM stored in the unit 13 and the current geomagnetic value TM is less than the predetermined threshold value, it is determined that the surrounding environment has not changed, and the power stored in the storage unit 13 is not turned off. By setting the current position information PS and direction information DR as the current position information PS and direction information DR, the current position can be recognized immediately after the power is turned on. Runode can present the current map screen and the route guidance screen according to the position or the like.

(6) Other Embodiments In the embodiment described above, the autonomous speed calculation unit 11 calculates and outputs the speed V and the corrected angular speed φc using the acceleration detection signal SA, the atmospheric pressure detection signal SR, and the angular speed φ. However, the present invention is not limited to this. For example, the angular velocity φ is supplied as it is to the navigation unit 12 without correction, or the acceleration in the three-axis direction is detected and the speed is calculated by a predetermined calculation process. The velocity V and the corrected angular velocity φc (or angular velocity φ) may be calculated and output by various other methods such as calculating V. In short, the position information PS is acquired from the GPS processing unit 10. It is only necessary that the current position can be calculated by the navigation unit 12 when it cannot be obtained. Furthermore, the configuration may be simplified so that the current position is not estimated by not calculating the velocity V and the corrected angular velocity φc (or angular velocity φ).

  In the above-described embodiment, the case where the position information PS and the direction information DR are stored as detection information has been described. However, the present invention is not limited to this, and for example, only the position information PS is stored. Alternatively, when the autonomous speed calculation unit 11 calculates and learns the offset correction value of the acceleration sensor 14 caused by the mounting angle of the cradle 4 with respect to the vehicle 100, the offset correction value is also stored as detection information. In addition, other various values representing the state of the navigation device 1 are stored and restored as detection information, such as restoring the offset correction value when the surrounding environment has not changed when the power is turned on again. May be.

  Further, in the above-described embodiment, on the condition that the navigation device 1 is mounted on the cradle 4, the geomagnetic value TM is stored before the power is turned off, and the change in the surrounding environment is determined when the power is turned on again. However, the present invention is not limited to this. For example, regardless of whether or not the navigation device 1 is mounted on the cradle 4, the geomagnetic value TM is stored before the power is turned off, and the power is turned on. A change in the surrounding environment may be determined when the power is turned on again.

  Further, in the above-described embodiment, on the condition that the navigation device 1 is stationary, the geomagnetic value TM is stored before the power is turned off, and the change in the surrounding environment is determined when the power is turned on again. However, the present invention is not limited to this. For example, regardless of whether or not the navigation device 1 is stationary, the geomagnetic value TM is stored before the power is turned off and the power is turned on again. A change in the surrounding environment may be determined.

  Further, in the above-described embodiment, when it is determined in step SP36 of the environment information restoration processing procedure RT3 (FIG. 8) that the surrounding environment has changed between before power-off and after power-on again, the geomagnetic value TM However, the present invention is not limited to this. For example, the geomagnetic value TM as the environment information is associated with the position information PS and the direction information DR as the detection information. May be stored in the storage unit 13 so as not to be deleted even when it is determined that the surrounding environment has changed before and after the power is turned off.

  In this case, even if the surrounding environment has changed after the power is turned on again and the position information PS and the direction information DR cannot be restored, one of the surrounding environments matches when the power is turned on next time. There is a possibility that the position information PS and the direction information DR associated with the matching surrounding environment may be restored.

  Thereby, for example, the geomagnetic value TM, the position information PS, and the direction information DR are stored in the storage unit 13 immediately before the navigation device 1 is removed from the cradle 4 of the vehicle 100, and then the navigation device 1 is stored in the user's home. When the power is turned on, the position information PS and the direction information DR are not restored because the geomagnetic values TM do not coincide with each other, but the navigation device 1 is mounted on the cradle 4 of the vehicle 100 next. When the power is turned on, since the geomagnetic values TM coincide with each other, the position information PS and the direction information DR can be restored, and a map screen corresponding to the current position can be immediately presented.

  Furthermore, in the above-described embodiment, whether the surrounding environment has changed based on whether the difference between the geomagnetic value TM stored in the storage unit 13 and the newly acquired geomagnetic value TM is less than a predetermined threshold value. Although the case where the determination is made is described (step SP34 of the detection information restoration processing procedure RT3), the present invention is not limited to this, and for example, the ratio between the two is within a predetermined range (for example, 0.9 to 1.1). In the following, etc.), it is determined whether the surrounding environment has changed by comparing the geomagnetic values TM by various comparison methods, such as determining whether the surrounding environment has changed. May be.

  Further, in the navigation device 1, by setting a threshold value (step SP34 of the detection information restoration processing procedure RT3) to be compared when calculating the difference of the geomagnetic value TM, the possibility of regarding the surrounding environment as the same is increased. Anyway.

  Thereby, for example, the vehicle 100 is actually moved before and after the power of the navigation device 1 is turned off, but the amount of change in the position and direction of the vehicle 100 is small and the position and direction are substantially the same. Even when the information can be regarded as being the same, the detection information can be restored by regarding the surrounding environment as the same. In this case, even if the restored position information PS and direction information DR have an error with respect to the correct position information PS and direction information DR at this time, this error is very small and is subsequently generated by the GPS processing unit 10. The position information PS can be corrected.

  Furthermore, in the above-described embodiment, the case where the triaxial geomagnetic sensor 17 is used to detect the triaxial geomagnetic value TM has been described. However, the present invention is not limited to this, for example, biaxial direction. Alternatively, a geomagnetic value in a biaxial direction or a monoaxial direction may be detected using a geomagnetic sensor in a uniaxial direction and used as environmental information. In this case, although the detection accuracy of the geomagnetism value is lower than in the case of using the triaxial geomagnetic sensor 17, the configuration of the navigation device 1 can be simplified, and the difference calculation process between the geomagnetism values can be simplified. .

  Further, in the above-described embodiment, the case where the stationary determination unit 23 determines whether or not the navigation device 1 is stationary based on the variance SAvar of the acceleration detection signal SA has been described. For example, the variance φvar of the angular velocity φ is calculated to determine whether or not the navigation device 1 is stationary based on the variance φvar, or the standard deviation of the acceleration detection signal SA is calculated. Various statistical calculation methods for various values may be used, such as determining whether or not the navigation device 1 is stationary based on the standard deviation.

  Further, in the above-described embodiment, the case where the position information PS is generated by the GPS processing unit 10 on the basis of the GPS signal received by the GPS antenna 2 has been described. Various satellite positioning systems such as zenith satellite system, GLONASS (Global Navigation Satellite System) and Galileo (GALILEO) are used, each positioning signal is received, positioning processing is performed, and position information PS is generated. Also good.

  Further, in the above-described embodiment, the case where the present invention is applied to the portable navigation device 1 has been described. However, the present invention is not limited to this. For example, a PDA (Personal Digital Assistant) having a navigation function, a mobile phone, You may make it apply this invention to the various electronic devices which implement | achieve a navigation function, without utilizing a vehicle speed pulse signal or the signal similar to this, such as a personal computer. In this case, the electronic device is not limited to the vehicle 100 and may be mounted on a ship, an aircraft, or the like.

  Further, in the above-described embodiment, the GPS processing unit 10 and the navigation unit 12 as the position detection unit, the geomagnetic sensor 17 as the geomagnetic sensor, the storage unit 13 as the storage unit, and the environmental change as the environment change determination unit. Although the case where the navigation device 1 as the position detection device is configured by the determination unit 31 and the initial information setting unit 32 as the initial information setting unit has been described, the present invention is not limited to this and includes various other circuit configurations. The position information calculation unit, the geomagnetic sensor, the storage unit, the environment change determination unit, and the initial information setting unit may constitute a position detection device.

  Furthermore, in the above-described embodiment, the GPS processing unit 10 and the navigation unit 12 as the position detection unit, the storage unit 13 as the storage unit, the environment change determination unit 31 as the environment change determination unit, and the initial information setting unit The case where the navigation device 1 as the navigation device is configured by the initial information setting unit 32 as the navigation unit 12 and the display unit 3 as the presentation unit has been described, but the present invention is not limited to this, and other various circuit configurations The navigation apparatus may be configured by a position information calculation unit, a storage unit, an environment change determination unit, an initial information setting unit, and a presentation unit.

  The present invention can also be used in various navigation devices that do not receive a signal such as a vehicle speed pulse signal.

It is a rough-line perspective view which shows the structure of a navigation apparatus and a cradle. It is a block diagram which shows the circuit structure of a navigation apparatus. It is an approximate line figure used for explanation of a calculation principle of an altitude change amount. It is an approximate line figure used for explanation of amendment of angular velocity. It is a flowchart which shows a speed output process sequence. It is a flowchart which shows a speed calculation process procedure. It is a flowchart which shows an environmental information storage processing procedure. It is a flowchart which shows a detection information restoration process procedure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Navigation apparatus, 2 ... GPS antenna, 3 ... Display part, 4 ... Cradle, 10 ... GPS processing part, 11 ... Autonomous speed calculation unit, 12 ... Navigation unit, 13 ... Memory | storage part, 17... Geomagnetic sensor 18. Cradle attachment / detachment detection unit 23. Stillness determination unit 30. Environmental information processing unit 31. Environment change determination unit 32. Initial information setting unit V. PS: Position information, DR: Direction information, MT: Geomagnetic value.

Claims (11)

A position detection unit that detects a current position based on positioning information supplied from a predetermined positioning unit and generates detection information related to the current position;
A geomagnetic sensor that detects a geomagnetic value in at least one axial direction;
A storage unit that stores the latest geomagnetic value detected by the geomagnetic sensor together with the latest detection information detected by the position detection unit,
An environment change determination unit that determines whether or not the surrounding environment has changed as compared to when the previous operation was stopped based on the geomagnetism value detected by the geomagnetic sensor when starting from an operation stop state;
An initial information setting unit that sets the detection information stored in the storage unit as initial detection information when the environment change determination unit determines that the surrounding environment has not changed since the previous operation stop. And a position detecting device comprising: The environment change determination unit
Based on whether or not the difference between the geomagnetic value detected by the geomagnetic sensor when starting from the operation stop state and the geomagnetic value stored in the storage unit is less than a predetermined threshold, The position detection device according to claim 1, wherein it is determined whether or not the environment has changed. The geomagnetic sensor
Detect the above geomagnetism value in three axes direction,
The storage unit
Storing the geomagnetism values in the three axis directions;
The environment change determination unit
Based on whether or not an error between the triaxial geomagnetic value detected by the geomagnetic sensor and the triaxial geomagnetic value stored in the storage unit is less than a predetermined threshold, The position detection apparatus according to claim 2, wherein it is determined whether or not the environment has changed. The position detector is
Detecting position information indicating the current position and direction information indicating a traveling direction of the position detection device;
The storage unit
Storing the latest position information, the latest direction information, and the latest geomagnetic value;
The initial information setting unit
When the environment change determination unit determines that the surrounding environment has not changed, the position information and the direction information stored in the storage unit are set as initial position information and initial direction information. The position detection device according to claim 1. A mounting detector for detecting whether or not the position detection device is mounted on a pedestal corresponding to the position detection device;
The storage unit
When it is detected by the mounting detector that the position detecting device is mounted on the pedestal, the latest geomagnetic value is stored together with the latest position information,
The environment change detection unit is
Determining whether or not the surrounding environment has changed when it is detected by the mounting detector that the position detecting device is mounted on the pedestal portion when starting from a non-operating state. The position detection device according to claim 1. A stationary state detecting unit for detecting whether or not the position detecting device is in a stationary state;
With
The storage unit
When the stationary state detecting unit detects that the stationary state is present, the latest geomagnetic value is stored together with the latest position information,
The environment change detection unit is
2. The apparatus according to claim 1, wherein when the apparatus is started from an operation stop state and is detected by the stationary state detection unit to be in the stationary state, it is determined whether or not the surrounding environment has changed. Position detection device. The stationary state detection unit is
The position detection device according to claim 6, wherein whether or not the position detection device is in a stationary state is detected based on the positioning information. An acceleration sensor for detecting acceleration, and
The stationary state detection unit is
The position detection device detects whether or not the position detection device is in a stationary state based on the magnitude of statistical variation in a predetermined time range of the speed calculated from the acceleration detected by the acceleration sensor. The position detection apparatus described in 1. A position detection step of detecting a current position based on positioning information supplied from a predetermined positioning means and generating detection information relating to the current position;
A storage step of storing the latest geomagnetic value detected by a geomagnetic sensor that detects at least one axial direction geomagnetic value together with the latest detection information detected by the position detection step in a predetermined storage unit;
An environment change determination step for determining whether or not the surrounding environment has changed as compared to when the previous operation was stopped based on the geomagnetism value detected by the geomagnetic sensor when starting from an operation stop state;
An initial information setting step for setting the detection information stored in the storage unit as initial detection information when it is determined in the environmental change determination step that the surrounding environment has not changed since the previous operation stop. A position detection method comprising: and. For the position detection device,
A position detection step of detecting a current position based on positioning information supplied from a predetermined positioning means and generating detection information relating to the current position;
A storage step of storing the latest geomagnetic value detected by a geomagnetic sensor that detects at least one axial direction geomagnetic value together with the latest detection information detected by the position detection step in a predetermined storage unit;
An environment change determination step for determining whether or not the surrounding environment has changed as compared to when the previous operation was stopped based on the geomagnetism value detected by the geomagnetic sensor when starting from an operation stop state;
An initial information setting step for setting the detection information stored in the storage unit as initial detection information when it is determined in the environmental change determination step that the surrounding environment has not changed since the previous operation stop. A position detection program characterized by causing and to be executed. A position detection unit that detects a current position based on positioning information supplied from a predetermined positioning unit and generates detection information related to the current position;
A storage unit that stores the latest geomagnetic value detected by a geomagnetic sensor that detects a geomagnetic value in at least one axial direction together with the latest detection information detected by the position detection unit,
An environment change determination unit that determines whether or not the surrounding environment has changed as compared to when the previous operation was stopped based on the geomagnetic value detected by the geomagnetic sensor when starting from the operation stop state;
An initial information setting unit that sets the detection information stored in the storage unit as initial detection information when the environment change determination unit determines that the surrounding environment has not changed since the previous operation stop. When,
A navigation device comprising: a presenting unit that presents the current position on a predetermined map or a route from the current position to a predetermined destination on the map based on the detection information .

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