JP3976758B2 - Navigation system and polarity setting method - Google Patents

Description

  The present invention relates to a navigation system.

  Currently, for example, as a positioning device for various mobile objects such as automobiles, airplanes, ships, etc., a current position position mark indicating the position of the mobile object is displayed at the point on the map including the point where the mobile object currently exists. 2. Description of the Related Art A so-called navigation system is known in which a superimposed display is performed and route guidance to a destination is performed based on the superimposed display. Among these navigation systems, navigation systems mounted on vehicles are roughly classified into a self-supporting navigation system and a GPS (Global Positioning System) type navigation system.

  The former calculates a current position using a travel distance sensor, an angular velocity sensor, or the like provided in a moving body, and displays a position mark and a corresponding map on a display screen based on the calculated current position.

  The latter receives positioning radio waves from a plurality of GPS satellites launched in outer space, calculates the current position of the moving object by the three-dimensional survey method or the two-dimensional survey method based on the reception result, and calculates Based on the current position, the position mark and the corresponding map are displayed on the display screen.

  Among these, the latter system using GPS positioning has the advantage that it is not necessary to set the vehicle position on the map in advance, and there is very little positioning error of the position and high reliability can be obtained. However, GPS positioning has the disadvantage that it cannot be measured in the shade of buildings, tunnels, forests, etc. In addition, self-supporting positioning is also susceptible to integration errors, cumulative errors, the effects of temperature changes, conditions inside and outside the vehicle body, etc. The detected data is not always accurate, and each positioning is not always perfect.

  Therefore, recently, a hybrid type vehicle navigation system configured to make use of both the GPS type positioning and the self-supporting positioning to compensate for the respective drawbacks is becoming common. This hybrid type navigation system can perform highly accurate positioning, but as a self-supporting positioning, positioning is performed using sensors installed in the vehicle in advance such as a mileage sensor, a back sensor, and a side brake. However, it is necessary to electrically connect the navigation device and the sensor, and there is a problem that the connection work becomes complicated.

Therefore, a navigation system has been proposed that includes an acceleration sensor that does not require electrical connection with a sensor installed in a vehicle. The navigation system equipped with the acceleration sensor acquires an output from the acceleration sensor, calculates an acceleration accompanying the movement of the vehicle based on the output, integrates the acceleration to calculate a speed, and further calculates the speed. The current position is measured by integrating and calculating the distance.
JP-A-5-288760

  In a conventional navigation system having an acceleration sensor, the sensing direction of the acceleration sensor and the traveling direction of the moving body differ depending on the mounting direction (installation direction) of the acceleration sensor with respect to the moving body or the navigation apparatus main body incorporating the acceleration sensor. In some cases, the acceleration in the traveling direction of the moving body may not be detected.

  That is, when the acceleration in the traveling direction of the moving body is detected, the installation direction of the acceleration sensor or the navigation apparatus body is limited, and there is a problem that the degree of freedom in the installation direction is low. In particular, when the sensitivity axis of the acceleration sensor is one axis (one direction), in order to use the acceleration sensor effectively, the installation direction of the acceleration sensor or the navigation device body is limited to one direction.

  Therefore, the present invention has been made in view of the above-described problems, and the problem is that the navigation apparatus main body is not limited in the installation direction, and a navigation system having a high degree of freedom in the installation direction with respect to the moving body is provided. It is to provide.

In order to solve the above-described problem, the navigation system according to claim 1 includes a first detection unit that detects acceleration in the first direction and an acceleration in a second direction that is 90 degrees with respect to the first direction. An acceleration detection means for detecting the acceleration of the moving body based on the output of the first detection section and the output of the second detection section, and whether or not the moving body is moving forward Determination means for determining whether or not, and setting means for setting the output polarity of the first detection unit and the output polarity of the second detection unit based on the output of the acceleration detection unit and the determination result of the determination unit; It is characterized by having.

In addition, the navigation system according to claim 5 includes a first detection unit that detects acceleration in the first direction and a second direction that detects acceleration in a second direction that is 90 ° with respect to the first direction. An acceleration detector that includes a detector and detects an acceleration of the moving body based on the output of the first detector and the output of the second detector; and the first detector and the second detector And a setting unit configured to set a detection unit that detects acceleration at the time of start of the moving body as a detection unit that detects acceleration in the front-rear direction of the moving body.

  Next, preferred embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the case where the present invention is applied to a vehicle navigation system in an automobile or the like will be described.

(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of the navigation system of the present invention. As shown in FIG. 1, the navigation system according to the present invention detects acceleration when a moving body, for example, a vehicle starts or stops, and when the vehicle is accelerated or decelerated as a self-supporting positioning means, and acceleration data For example, an angular velocity sensor 2 as one of displacement detecting means for detecting angular velocity when the vehicle changes its direction and outputting angular velocity data and relative bearing data, and, for example, a vehicle speed pulse per one revolution of the axle. A travel distance sensor 3 that detects a travel distance per unit time based on the number and outputs travel distance data is provided.

  Here, since the travel distance of the vehicle is calculated based on the output of the acceleration sensor 1, the connection between the travel distance sensor 3 of the vehicle and the navigation device is not necessarily required. The combined use of the travel distance sensor 3 and the acceleration sensor 1 improves the travel distance detection accuracy.

  And as a GPS type positioning means, it receives radio waves from GPS satellites and outputs GPS positioning data such as latitude, longitude, altitude and speed where the moving body is present, and also outputs absolute direction data of the traveling direction of the vehicle GPS receiver 4 is provided.

  Further, the current position is calculated based on the acceleration data, the relative azimuth data, the angular velocity data, the GPS positioning data, and the absolute azimuth data output from the acceleration sensor 1, the angular velocity sensor 2 and the GPS receiver 4 via the bus line 10. In addition, it includes a system controller 5 that controls the entire navigation device, and an input device 11 that includes a remote controller for inputting various data.

  Further, a DVD-ROM drive 12a for reproducing a DVD-ROM (Digital Video Disk Read Only Memory) disk DK1 or a CD-ROM (Compact Disk Read Only Memory) disk DK2 storing map information under the control of the system controller 5, respectively. Alternatively, the CD-ROM drive 12b, the display unit 13 for displaying various display data under the control of the system controller 5, and the sound reproduction unit 18 for reproducing and outputting various audio data under the control of the system controller 5. , And a VICS receiving unit 22 that receives traffic information by VICS (Vehicle Information and Communication System).

  The system controller 5 includes an interface unit 6 that performs interface operations of the various sensors described above, a CPU 7 that controls the entire system controller 5, and a ROM (Read Only Memory) 8 that stores a control program executed by the CPU 7. And a RAM (Random Access Memory) 9 for storing various readable data such as route data set in advance by the user via the input device 11, and the input device 11, the DVD-ROM drive 12a or The CD-ROM drive 12 b, the display unit 13, the sound reproduction unit 18, and the VICS receiver 22 are connected via the bus line 10. The various sensors are connected via the interface unit 6 and the bus line 10.

  The display unit 13 is a graphics controller 14 that controls the entire display unit 13 based on control data sent from the CPU 7 via the bus line 10 and image information that can be displayed immediately, such as a VRAM (Video RAM). A buffer memory 15 for temporarily storing the image data, and a display control unit 16 for controlling the display 17 such as a liquid crystal display device or a CRT (Cathode Ray Tube) based on the image data output from the graphics controller 14. It is prepared for.

  The sound reproduction unit 18 includes a D / A converter 19 that performs D / A conversion of an audio digital signal sent from the DVD-ROM drive 12a, the CD-ROM drive 12b, or the RAM 9 via the bus line 10, and a D / A converter 19 Is provided with an amplifier 20 for amplifying the audio analog signal output from the speaker, and a speaker 21 for converting the amplified audio analog signal into audio and outputting it.

  Further, the “navigation device main body” in each of the following embodiments indicates a casing in which at least the system controller 5 such as the CPU 7, the DVD-ROM drive 12 a, and the CD-ROM drive 12 b are accommodated.

  When the navigation system having the above configuration is activated, the system controller 5 first needs to display information for accessing map information and the like from the DVD-ROM disc DK1 or CD-ROM disc DK2 and the vehicle position mark. Information is read out and stored in the RAM 9.

  Next, the acceleration is calculated based on the output of the acceleration sensor 1 as described later, and the speed and the travel distance are obtained from the calculated acceleration. Further, the traveling direction is calculated based on the output of the angular velocity sensor 2. Based on the travel distance data, the traveling direction data, and the GPS positioning data from the GPS receiver 4, the current position of the host vehicle is calculated to obtain the current position of the vehicle.

  Then, the obtained map data around the current position is read from the DVD-ROM disk DK1 or the CD-ROM disk DK2 and sent to the graphics controller 14, and the map of the current position is displayed on the display 17.

  Hereinafter, a specific method for calculating the acceleration and speed based on the output of the acceleration sensor 1 and the travel distance will be described. In addition, the acceleration sensor 1 or the navigation device body in which the acceleration sensor 1 is built is used to detect the acceleration in the vehicle front-rear direction (traveling direction) by the acceleration sensor 1 and the output of the acceleration sensor 1 when the vehicle is accelerated. The description will be made assuming that the vehicle is installed in the positive direction.

  FIG. 2 is a block diagram showing a procedure for processing the output from the acceleration sensor 1. As shown in FIG. 2, the noise corresponding to the acceleration generated in the vehicle detected from the acceleration sensor main body 1a through the detection circuit 1b is removed by the low-pass filter 1c, and then the sampling period T is obtained by the A / D converter 1d. A / D conversion is performed m times during the period. The processing described below is performed by the CPU 7.

  The A / D converted output of the acceleration sensor main body 1a is averaged for the sampling period T by the averaging processing means 1e, and the average value a of the acceleration sensor output values for the sampling period T for each sampling period T. 'n is calculated. For example, the sampling period T is 0.1 s, and 10 A / D conversions are performed during this period.

  Next, since the offset value aoe is set in advance in the output of the acceleration sensor 1, the offset value is subtracted from the average value a'n, and further multiplied by a predetermined gain and a gain correction coefficient. Acceleration occurring in is calculated. The calculated acceleration An is stored and held in a shift register (not shown) or the like.

An = Cx.Gk.G. (A'n-aoe) (1)
Here, An is the vehicle acceleration [m / s2] at the sampling time nT, Gk is the gain correction coefficient, and G is the gain [m / s2] of the acceleration sensor 1. Both Gk and G do not always take a constant value, but are set to appropriate values according to the use situation. Cx is a polarity coefficient determined according to the installation direction of the acceleration sensor 1, and takes a value of +1 or -1. The initial state is set to Cx = + 1. As will be described later, the polarity of the output of the acceleration sensor 1 is switched by switching Cx. a′n is the average value of the acceleration sensor output values during the sampling period T, and aoe is the offset value of the acceleration sensor 1.

Here, assuming that the running state of the vehicle in the sampling period T is equal acceleration linear motion, the vehicle speed change amount ΔVn [km / h] at the sampling time nT is obtained by the equation (2) where T is the sampling period. It is done.
ΔVn = (3600/1000) ・ An ・ T (2)
Here, (3600/1000) is a coefficient for converting the unit from second [s] to time [h] and from meter [m] to kilometer [km].

The vehicle speed Vn [km / h] at the sampling time nT is calculated from the speed Vn-1 at the previous sampling time (n-1) T and the speed change ΔVn of the vehicle at the sampling time nT by the equation (3). Desired.
Vn = .DELTA.Vn + Vn-1 (3)

The change amount ΔDn [m] of the travel distance of the vehicle at the sampling time nT is obtained by the equation (4).
ΔDn = (1/2) An An T2 + (1000/3600) Vn-1 T (4)

Therefore, the cumulative travel distance Dn [m] of the vehicle at the sampling time nT is calculated from the cumulative travel distance Dn-1 at the previous sampling time (n−1) T and the change amount ΔDn of the travel distance of the vehicle at the sampling time nT. It is calculated | required by (5) Formula.
Dn = ΔDn + Dn−1 (5)

  By performing the above calculation mainly by the CPU 7, the speed and travel distance of the vehicle can be obtained based on the output of the acceleration sensor 1, and used for processing such as estimation of the current position.

  Alternatively, a single-axis sensor may be used as the acceleration sensor, and two sensors may be used in directions of 90 ° to each other (X-axis and Y-axis directions), and acceleration may be detected in two directions. In this case, by including the acceleration sensor 1x that detects the longitudinal acceleration of the vehicle and the acceleration sensor 1y that detects the lateral acceleration of the vehicle, the lateral acceleration generated when the vehicle travels in a curve can also be obtained. It will be. The output of the acceleration sensor 1y is also processed based on the above formulas (1) to (5).

  Although not shown, an acceleration sensor in the Z-axis direction, which is the acceleration in the vertical direction with respect to the vehicle, can be combined, and by detecting a change in gravitational acceleration caused by the inclination of the vehicle body, a change in the altitude of the vehicle (in the vertical direction) (Movement amount) can also be detected.

  Hereinafter, the configuration for accurately detecting the acceleration according to the traveling direction of the vehicle regardless of the direction in which the acceleration sensor 1 or the navigation apparatus body incorporating the acceleration sensor 1 is installed in the vehicle will be described in detail.

  In the navigation device of the first embodiment, the acceleration sensor main body is attached to an arbitrary rotatable rotation mechanism, and the acceleration sensor main body with respect to the installation direction of the navigation device main body incorporating the acceleration sensor 1 in the vehicle. The rotation mechanism is driven so as to detect the acceleration in the traveling direction of the vehicle.

  FIG. 3 is a schematic diagram showing a structure of a rotation mechanism unit to which the acceleration sensor main body 1a is attached. 3A and 3B show the case where the acceleration sensing direction of the acceleration sensor 1 is one axis in the X-axis direction as shown in the figure, and FIG. 3A is a view when the rotation mechanism is viewed from above. FIG. 3B is a view of the rotating mechanism as viewed from the side.

  The acceleration sensor 1 is attached to an internal chassis or a substrate 101 of the navigation apparatus via a rotatable mounting base 102. In this example, a click stop recess 103 is provided at every 90 ° on the periphery of the mounting base 102 and is configured to engage with a protrusion provided on the click stop guide 104. A possible mounting base 102, internal chassis or substrate 101, and click stop guide 104 constitute a rotation mechanism.

  By providing the mounting table 102 with a recess every 90 °, the mounting table 102 is engaged with the convex portion provided in the click stop guide 104 every time the mounting table 102 is rotated 90 °, so that the mounting table 102 is rotated every 90 °. It is fixed to the internal chassis or the substrate 101 or the like. By being fixed, the mounting base 102 to which the acceleration sensor 1 is attached does not move freely due to vibration of the vehicle or the like, and the acceleration in the fixed direction can always be detected.

  Therefore, regardless of the direction of installation of the navigation device body incorporating the acceleration sensor 1 in the vehicle, if the acceleration sensing direction of the acceleration sensor is fixed to the traveling direction of the vehicle by driving and rotating the rotation mechanism, The acceleration in the traveling direction of the vehicle can always be detected. In the case of the above example, since it can be fixed every 90 ° rotation, the installation direction of the navigation device body incorporating the acceleration sensor 1 in the vehicle can be selected from four directions.

  The method of rotating the mounting base 102 is not particularly limited. For example, a knob or lever that is integrally formed with the mounting base 102 and that can be operated by a user is provided, and the mounting base 102 is attached by rotating the knob or lever. The table 102 may be rotated, or the rotation amount or the fixing direction may be instructed from an input device such as a remote controller, and may be driven by a motor or the like. When the above-described knob or lever is provided, the acceleration sensor 1 accurately determines the acceleration in the traveling direction of the vehicle to the user by configuring the knob or lever to have a directional shape or adding a mark. A fixing direction to be detected can be instructed from a manual or the like.

  In addition, since the acceleration sensor may be selected in a fixed direction only when it is attached to the vehicle, a selection hole may be provided in the casing of the navigation device and driven by a driver or the like.

  Alternatively, the acceleration sensor may be mounted in two directions by attaching a single-axis sensor to the mounting base 102 and two sensors attached in directions of 90 ° to each other (X-axis and Y-axis directions). In this case, the acceleration sensor 1x for detecting the longitudinal acceleration of the vehicle and the acceleration sensor 1y for detecting the lateral acceleration of the vehicle are arranged on the mounting base 102 as shown in FIG. Of course, the acceleration sensor 1z for detecting the acceleration in the Z-axis direction may be further attached to set the sensing direction to three directions.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The schematic configuration of the navigation system of this embodiment is the same as that of the first embodiment. In the second embodiment, the polarity of the acceleration sensor 1 is switched by the user operating the polarity switch according to the direction in which the acceleration sensor 1 or the navigation apparatus body incorporating the acceleration sensor 1 is installed in the vehicle. It is a thing.

  FIG. 4 is a diagram showing the relationship between the installation direction of the navigation device body in the vehicle and the polarity changeover switch when the navigation device body incorporates an acceleration sensor having a single sensing direction (one axis). When an acceleration sensor with a sensing direction of one direction (one axis) is used, in order to detect the acceleration in the traveling direction of the vehicle, the two installation directions shown in FIGS. Directions are possible.

  FIG. 4A shows a case where the navigation apparatus body is installed in the vehicle so that a disk insertion slot for inserting a DVD-ROM disc or CD-ROM disk into the navigation apparatus body faces the front of the vehicle. In addition, when the navigation device body is installed as shown in FIG. 4A, an acceleration sensor is attached to the navigation device body so that the acceleration in the traveling direction of the vehicle is accurately (so that a positive output is obtained when the vehicle moves forward). It has been.

  When the navigation device main body is installed as shown in FIG. 4A, a positive output is obtained from the acceleration sensor when the vehicle moves forward. Therefore, the switch SW is turned off, that is, the polarity of the acceleration sensor output not shown is reversed. "L" is given as information from the switch SW to the circuit, and the polarity coefficient Cx for the acceleration sensor 1 is set to +1.

  FIG. 4B shows a case where the navigation device body is installed in the vehicle so that the disc insertion opening faces the rear of the vehicle. When the navigation device main body is installed as shown in FIG. 4B, a negative output is obtained from the acceleration sensor 1 when the vehicle moves forward. Therefore, the switch SW is turned on, that is, the polarity of the acceleration sensor output (not shown) "H" is given as information from the switch SW to the inverting circuit, and Cx is set to -1.

  When Cx is set to −1, a negative output is obtained from the acceleration sensor when the vehicle moves forward, but the acceleration calculated by the above equation (1) depends on the direction of the traveling direction of the vehicle. It becomes acceleration, and the acceleration in the traveling direction of the vehicle can be accurately detected.

  For the user, for example, “If the main unit is installed so that the disc insertion slot is at the rear of the vehicle, turn on the changeover switch. Install the main unit so that the disc insertion port is at the front of the vehicle. In such a case, the switch should be turned off. ”, And the switch operation may be performed when the navigation system is attached to the vehicle.

  Next, for example, a uniaxial acceleration sensor 1x, 1y is arranged in a direction of 90 ° with respect to each other (X axis, Y axis direction), and navigation incorporating a built-in acceleration sensor having two sensing directions in the X axis and Y axis directions. The case of the apparatus main body will be described.

  FIG. 5 shows the relationship between the installation direction of the navigation device body in the vehicle and the polarity switch of the acceleration sensor in the case of a navigation device body incorporating an acceleration sensor having a sensing direction in two directions of the X-axis and Y-axis directions. FIG. Since the sensing direction of the acceleration sensor is two directions, two polarity changeover switches including SWx for the acceleration sensor 1x and SWy for the acceleration sensor 1y are used to switch the polarity independently.

  When an acceleration sensor having two sensing directions (two axes) is used, the four installation directions shown in FIGS. 5A, 5B, 5C, and 5D can be considered as the installation directions of the navigation apparatus body.

  FIG. 5A shows a case where the navigation apparatus main body is installed in the vehicle such that a disk insertion slot for inserting a DVD-ROM disc or CD-ROM disk into the navigation apparatus main body faces the front of the vehicle. Further, when the navigation apparatus main body is installed as shown in FIG. 5A, the acceleration sensors 1x and 1y accurately determine the acceleration in the traveling direction of the vehicle and the acceleration in the lateral direction of the vehicle without switching the polarity ( The acceleration sensor main body detects the acceleration so that the acceleration generated when the vehicle moves forward with the acceleration sensor 1x becomes positive, and the acceleration generated rightward of the vehicle with the acceleration sensor 1y becomes positive. It shall be attached to.

  When the navigation apparatus main body is installed with the disc insertion opening facing the front of the vehicle as shown in FIG. 5A, a positive output is obtained from the acceleration sensor 1x when acceleration in the forward direction of the vehicle is detected, and the vehicle When the acceleration generated in the right direction is detected, a positive output is made from the acceleration sensor 1y. Therefore, both the switches SWx and SWy are turned off, that is, from the switches SWx and SWy to the polarity inversion circuit of the outputs of the acceleration sensors 1x and 1y. Both “L” are given as the information of, and the polarity coefficient Cx for the acceleration sensor 1x and the polarity coefficient Cy for the acceleration sensor 1y are both set to +1.

  Further, when both “L” are output as information from the switches SWx and SWy, the CPU 7 generates acceleration generated in the longitudinal direction of the vehicle by the acceleration sensor 1x and acceleration generated in the lateral direction of the vehicle by the acceleration sensor 1y. Recognize that is detected.

  FIG. 5B shows the case where the navigation device body is installed in the vehicle so that the disc insertion opening faces the right side of the vehicle. When the navigation device main body is installed as shown in FIG. 5B, the acceleration sensor 1x detects acceleration generated in the left-right direction of the vehicle, and the acceleration sensor 1y detects acceleration in the front-rear direction of the vehicle. .

  As is clear from FIG. 5B, since the direction of the acceleration sensor 1y and the direction of the traveling direction of the vehicle are opposite, the acceleration generated when the vehicle advances by the acceleration sensor 1y is a negative output, and the acceleration sensor 1x Thus, the acceleration generated in the right direction of the vehicle is detected as a positive output. In this case, the switch SWx is turned off and the switch SWy is turned on, “L” is given as information from the switch SWx to the polarity inversion circuit of the output of the acceleration sensor 1x, and Cx for the acceleration sensor 1x is set to +1. Then, "H" is given as information from the switch SWy to the polarity inversion circuit of the output of the acceleration sensor 1y, and Cy for the acceleration sensor 1y is set to -1.

Further, when “L” is output as information from the switch SWx and “H” is output from the switch SWy, the CPU 7 causes the acceleration sensor 1y to generate acceleration generated in the left-right direction of the vehicle by the acceleration sensor 1x. Recognize that the acceleration generated in the longitudinal direction of the vehicle is detected.

  FIG. 5C shows the case where the navigation apparatus body is installed in the vehicle so that the disc insertion opening faces the rear of the vehicle. When the navigation apparatus main body is installed as shown in FIG. 5C, the acceleration sensor 1x detects acceleration generated in the front-rear direction of the vehicle, and the acceleration sensor 1y detects acceleration in the left-right direction of the vehicle. .

  As is clear from FIG. 5C, the acceleration generated when the vehicle moves forward with the acceleration sensor 1x is detected as a negative output, and the acceleration generated rightward of the vehicle is detected as a negative output with the acceleration sensor 1y. become. In this case, the switches SWx and SWy are both turned on, and both the switches SWx and SWy are turned on, that is, as information from the switches SWx and SWy to the polarity inversion circuit of the outputs of the acceleration sensors 1x and 1y. H "is set, and Cx for the acceleration sensor 1x and Cy for the acceleration sensor 1y are both set to -1.

  Further, when “H” is output as information from the switches SWx and SWy, the CPU 7 generates acceleration generated in the longitudinal direction of the vehicle by the acceleration sensor 1x and acceleration generated in the lateral direction of the vehicle by the acceleration sensor 1y. Recognize that is detected.

  FIG. 5D shows the case where the navigation apparatus body is installed in the vehicle so that the disc insertion opening faces the left side of the vehicle. When the navigation device main body is installed as shown in FIG. 5D, the acceleration sensor 1x detects acceleration generated in the left-right direction of the vehicle, and the acceleration sensor 1y detects acceleration in the front-rear direction of the vehicle. .

  As is clear from FIG. 5D, the acceleration generated when the vehicle moves forward with the acceleration sensor 1y is detected as a positive output, and the acceleration generated rightward of the vehicle is detected as a negative output with the acceleration sensor 1x. become. In this case, the switch SWx is turned on and the switch SWy is turned off, "H" is given as information from the switch SWx to the polarity inversion circuit of the output of the acceleration sensor 1x, and Cx for the acceleration sensor 1x is set to -1. Then, “L” is given as information from the switch SWy to the polarity inverting circuit of the output of the acceleration sensor 1y, and Cy for the acceleration sensor 1y is set to +1.

  Further, when “H” is output as information from the switch SWx and “L” is output from the switch SWy, the CPU 7 causes the acceleration sensor 1y to generate acceleration generated in the left-right direction of the vehicle by the acceleration sensor 1x. Recognize that the acceleration generated in the longitudinal direction of the vehicle is detected.

  Therefore, the acceleration generated in the vehicle can be accurately detected when the user operates the polarity switch according to the setting direction of the acceleration sensor or the navigation apparatus main body incorporating the acceleration sensor. Further, when the acceleration sensor is built in the navigation device, the mounting direction (fixed direction) of the acceleration sensor is not limited to the above-described example. In short, the polarity may be switched according to the direction in which the acceleration sensor is fixed with respect to the navigation device body and the direction in which the navigation device body is installed in the vehicle.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the second embodiment, the configuration is such that the user operates the polarity changeover switch SW in order to make the CPU 7 recognize the direction of installation of the acceleration sensor or the navigation apparatus body incorporating the acceleration sensor in the vehicle.

  In the third embodiment, the display unit such as a CRT or a liquid crystal display device displays an acceleration sensor or a plurality of candidates for the installation direction of the navigation device body in which the acceleration sensor is built in the vehicle, and the user can select a plurality of candidates. By selecting the actual installation direction from the inside, that is, instead of operating the polarity switch SW, the installation direction to the vehicle is input on the display screen, and the polarity of the acceleration sensor and the direction of the acceleration sensor are changed. The CPU 7 is made to recognize.

  FIG. 6 is an example of a display screen for selecting an installation direction of the acceleration sensor or the navigation apparatus main body incorporating the acceleration sensor in the vehicle. FIG. 6A shows a case where the sensing direction of the acceleration sensor is one direction (one axis), and FIG. 6B shows a case where the sensing direction of the acceleration sensor is two directions (two axes).

  When the user operates a cursor key provided on the input device 11 such as a remote controller to select an item for switching the mounting direction of the acceleration sensor (in the figure, the acceleration sensor is a G sensor), candidates for directions that can be set Are displayed as shown in FIGS. 6 (a) and 6 (b).

  From the displayed installation direction candidates, the direction in which the user has actually attached to the vehicle is selected. In this case, for example, if the direction of installation of the navigation device main body with the built-in acceleration sensor in the vehicle is selected, an insertion port for inserting a disk is provided in the vehicle as shown in FIG. 5 of the second embodiment. On the other hand, it may be selected whether it is facing forward, backward, left or right.

  Next, the procedure for switching the polarity of the acceleration sensor according to the third embodiment will be described with reference to the flowchart of FIG. The flowchart of FIG. 7 corresponds to the case where the acceleration sensor senses two directions (two axes).

  When the user selects a direction actually attached to the vehicle from the displayed installation direction candidates, if it is determined that “front direction” is selected in step S30, the navigation device main body is displayed in FIG. Since it is a time of installation as shown in a), the process proceeds to step S31, Cx for the acceleration sensor 1x and Cy for the acceleration sensor 1y are both set to +1, and the process proceeds to step S34.

  If it is determined in step S30 that “forward” has not been selected, it is determined in step S32 whether or not “rear” has been selected. Since it is when it is installed as shown in FIG. 5 (c), the process proceeds to step S33, Cx for the acceleration sensor 1x and Cy for the acceleration sensor 1y are both set to -1, and the process proceeds to step S34.

  In step S34, the acceleration sensor 1x detects the acceleration generated in the front-rear direction of the vehicle, recognizes that the acceleration generated in the left-right direction of the vehicle is detected by the acceleration sensor 1y, and switches the polarity of the acceleration sensor. finish.

  If it is determined in step S32 that “rearward” has not been selected, it is determined in step 35 whether “rightward” has been selected. When the “right direction” is selected, the navigation apparatus main body is installed as shown in FIG. 5B. Therefore, the process proceeds to step S36, where Cx for the acceleration sensor 1x is +1 and Cy for the acceleration sensor 1y is −1. To go to step S39.

  If it is determined in step S35 that “right” is not selected, the process proceeds to step S37 to determine whether “left” is selected. If the “left direction” is selected, the navigation apparatus main body is installed as shown in FIG. 5D. Therefore, the process proceeds to step S38, where Cx for the acceleration sensor 1x is −1 and Cy for the acceleration sensor 1y is +1. To go to step S39.

  If it is determined in step S37 that the “left direction” has not been selected, no direction has been selected, and the process returns to step S30.

  In step S39, acceleration generated in the left-right direction of the vehicle is detected by the acceleration sensor 1x, and it is recognized that the acceleration generated in the front-rear direction of the vehicle is detected by the acceleration sensor 1y. finish.

  The process of switching the polarity of the acceleration sensor according to the third embodiment is completed by the above-described procedure, and the acceleration, the moving speed, and the travel distance generated in the vehicle are calculated based on the output of the acceleration sensor.

(Fourth embodiment)
Next, the 4th Embodiment of this invention is described based on FIG.8 and FIG.9. The schematic configuration of the navigation system of the present embodiment is the same as that shown in the first embodiment.

  In the fourth embodiment, from a sensor other than an acceleration sensor, for example, a travel distance sensor 3 that detects a travel distance per unit time based on GPS positioning data and the number of vehicle speed pulses per one rotation of the axle and outputs travel distance data. Using the speed obtained based on this data and the speed obtained from the acceleration sensor, the installation direction of the acceleration sensor or the navigation device body incorporating the acceleration sensor in the vehicle is detected, and the polarity of the acceleration sensor output is determined. It is to be switched.

  FIG. 8 shows a procedure for detecting the direction of installation of an acceleration sensor or a navigation apparatus main body incorporating an acceleration sensor in a vehicle when using an acceleration sensor having a single sensing direction (one axis) and switching the polarity of the acceleration sensor output. It is a flowchart which shows.

  First, the acceleration An [m / s2] of the current vehicle is calculated using the above-described equation (1) (step S51).

  In step S52, it is determined whether the GPS is in a positioning state. If the GPS is in the positioning state, the process proceeds to the next step S53 with Yes, and if the GPS is not in the positioning state, the end is NO.

  In step S53, it is determined whether or not the speed data Vgps obtained by GPS positioning is greater than a predetermined speed Vth. Here, Vth uses 30 [km / h]. This is because, in general, in the daily running state, the reverse running is not performed at 30 [km / h], and therefore, if it is 30 [km / h] or more, it can be determined that the vehicle is moving forward.

  If the speed data Vgps obtained by GPS positioning is larger than the speed Vth, that is, if it is 30 [km / h] or more, it is assumed that the vehicle is moving forward, and the process proceeds to the next step in Yes. When the speed data Vgps is smaller than the speed Vth, if the speed data is less than 30 [km / h], the vehicle may not be moving forward and the vehicle may be stopped or moving backward. Cancel and end.

  In step S54, it is determined whether or not the speed Vac obtained from the output of the acceleration sensor is negative. If it is negative, the vehicle is traveling backward as long as the speed obtained from the output of the acceleration sensor is seen. However, in step S53, the current vehicle speed cannot be normal back traveling. It can be seen that the installation direction of the acceleration sensor or the navigation device body incorporating the acceleration sensor is installed in the direction opposite to the traveling direction of the vehicle.

  Therefore, if the speed Vac is negative, Cx is set to -1 in step S55, the polarity of the acceleration sensor output is inverted, and the polarity of the acceleration sensor output is switched. Here, it is assumed that Cx is set to +1 in the initial state.

  When the speed Vac is not negative, the installation direction of the acceleration sensor or the navigation apparatus main body incorporating the acceleration sensor coincides with the traveling direction of the vehicle, and Cx may remain +1. In step S54, the result is No, and the polarity of the acceleration sensor output is switched and the process is terminated.

  Then, after switching the polarity of the acceleration sensor output, an acceleration, a moving speed, and a travel distance generated in the vehicle are obtained from the acceleration sensor output.

  FIG. 9 shows an acceleration sensor having uniaxial acceleration sensors 1x and 1y arranged at 90 ° directions (X-axis and Y-axis directions) and having sensing directions in two directions of the X-axis and Y-axis directions. It is a flowchart which shows the procedure which detects the installation direction to the vehicle of the navigation apparatus main body incorporating this acceleration sensor, and switches the polarity of an acceleration sensor output.

  First, in step S70, it is determined which of the acceleration sensors 1x and 1y has detected the acceleration at the start of the vehicle. When the acceleration at the time of start is detected by the acceleration sensor 1x, it is found in step S71 that the acceleration sensor 1x is in the front-rear direction of the vehicle and the acceleration sensor 1y is in the left-right direction of the vehicle. When the acceleration at the time of start is detected by the acceleration sensor 1y, it is found in step S72 that the acceleration sensor 1x is in the left-right direction of the vehicle and the acceleration sensor 1y is in the front-rear direction of the vehicle.

  Next, the acceleration An [m / s2] of the current vehicle is calculated from the acceleration sensor (one of 1x and 1y) detecting the longitudinal acceleration of the vehicle using the above-described equation (1) ( Step S73).

  In step S74, it is determined whether the GPS is in a positioning state. If the GPS is in the positioning state, the process proceeds to the next step S75 with Yes, and if the GPS is not in the positioning state, the end is NO.

  In step S75, it is determined whether or not the speed data Vgps obtained by GPS positioning is greater than a predetermined speed Vth.

  If the speed data Vgps obtained by GPS positioning is greater than the speed Vth, that is, if it is 30 [km / h] or more, it is assumed that the vehicle is moving forward, and the process proceeds to step S76 in Yes. When the speed data Vgps is smaller than the speed Vth, if the speed data is less than 30 [km / h], the vehicle may not be moving forward and the vehicle may be stopped or moving backward. Cancel and end.

  In step S76, it is determined whether or not the speed Vac obtained from the output of the acceleration sensor is negative. If the speed Vac is negative, it is determined in step S77 whether or not it is the acceleration sensor 1x that detects the longitudinal acceleration of the vehicle.

  If it is the acceleration sensor 1x that detects the longitudinal acceleration of the vehicle, the process proceeds to step S78. Since the installation directions of the acceleration sensors 1x and 1y at this time are as shown in FIG. 5C, both Cx for the acceleration sensor 1x and Cy for the acceleration sensor 1y are set to -1.

  If the acceleration sensor 1y detects the longitudinal acceleration of the vehicle, the process proceeds to step S79. Since the installation directions of the acceleration sensors 1x and 1y are as shown in FIG. 5B, Cx for the acceleration sensor 1x is set to +1 and Cy for the acceleration sensor 1y is set to -1.

  If the speed Vac is positive, it is determined in step S80 whether or not it is the acceleration sensor 1x that detects the longitudinal acceleration of the vehicle.

  If the acceleration sensor 1x detects the longitudinal acceleration of the vehicle, the process proceeds to step S81. Since the installation directions of the acceleration sensors 1x and 1y at this time are as shown in FIG. 5A, both Cx for the acceleration sensor 1x and Cy for the acceleration sensor 1y are set to +1.

  If the acceleration sensor 1y detects the longitudinal acceleration of the vehicle, the process proceeds to step S82. Since the installation directions of the acceleration sensors 1x and 1y are as shown in FIG. 5D, Cx for the acceleration sensor 1x is set to -1 and Cy to the acceleration sensor 1y is set to +1.

  Through the above steps, the acceleration sensor having a sensing direction in two directions of the X-axis and Y-axis directions or the installation direction of the navigation device main body incorporating the acceleration sensor in the vehicle is detected and the polarity of the acceleration sensor output is switched. The acceleration, the moving speed and the travel distance generated in the vehicle are obtained from the output of the acceleration sensor.

  In addition, when using an acceleration sensor with sensing directions in three directions, the X-axis, Y-axis, and Z-axis, the navigation device itself is not only placed horizontally (installed as shown in FIG. 5), but also placed vertically (disc inserted). (Installation state with mouth facing upward) is also possible. At this time, if the acceleration sensor that detects the acceleration in the traveling direction of the vehicle is selected from the three, the polarity of each acceleration sensor can be switched by the method described above.

  In the flowcharts of FIGS. 8 and 9, the speed data Vgps obtained by GPS positioning in step S53 of FIG. 8 and step S75 of FIG. 9 is recognized from the predetermined speed Vth in order to recognize that the vehicle is in the forward direction. Is also used. This is based on the fact that the back travel is generally not performed at 30 [km / h] in the daily travel state.

  However, it is possible that the back travel is performed at 30 [km / h] or more while switching the polarity of the acceleration sensor output in FIGS. When the flowcharts of FIGS. 8 and 9 are executed while the vehicle is traveling at a speed of 30 [km / h] or more, it is determined that the vehicle is moving forward despite being backed. Therefore, the polarity of the acceleration sensor is set in reverse.

  Therefore, if the polarity of the acceleration sensor output shown in FIGS. 8 and 9 is always executed when the vehicle is moving forward, the polarity can be surely changed. In a general navigation system, the vehicle is always moved forward at the initial setting of the sensor. Therefore, the polarity of the acceleration sensor may be switched at the same time at the initial setting of the sensor.

  Further, in order to ensure that the vehicle is moving forward, the state in which the speed data Vgps obtained by GPS positioning exceeds step S53 in FIG. 8 and step S75 in FIG. 9 exceeds a predetermined speed Vth for a predetermined time. (For example, 5 seconds) It may be a condition as to whether it has continued. This is because, for example, it is unlikely that the back travel is 30 [km / h] or more and continues for 5 seconds in a normal travel state.

  Further, in determining that the vehicle is moving forward, the vehicle travel distance is obtained from the GPS positioning data, and when the vehicle travels more than a predetermined travel distance (for example, 200 m that cannot be considered as normal back travel), the period When the speed or distance obtained from the output of the middle acceleration sensor shows a negative value, it may be determined that the acceleration sensor is reversed.

  As described above in detail, according to the present embodiment, when the acceleration sensor is used in the navigation device, the mounting direction of the acceleration sensor can be easily changed after being mounted on the vehicle, and the mounting direction of the acceleration sensor can be freely set. Can have a degree.

It is a block diagram which shows the whole structure of the navigation apparatus in each embodiment of this invention. It is a block diagram which shows the means to process the output from the acceleration sensor in each embodiment of this invention. It is a conceptual diagram which shows the structure of the internal chassis or board | substrate which attaches the acceleration sensor by the 1st Embodiment of this invention. It is a figure explaining the state of the polarity changeover switch of the uniaxial acceleration sensor by the 2nd Embodiment of this invention, and the polarity of acceleration. It is a figure explaining the state of the polarity changeover switch of the biaxial acceleration sensor by the 2nd Embodiment of this invention, and the polarity of acceleration. It is an example of the display screen which selects the installation direction by the 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of polarity switching of the biaxial acceleration sensor output by the 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of polarity switching of the uniaxial acceleration sensor output by the 4th Embodiment of this invention. It is a flowchart which shows the process sequence of polarity switching of the biaxial acceleration sensor output by the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Acceleration sensor 1a ... Acceleration sensor main body 1b ... Detection circuit 1c ... Low pass filter 1d ... A / D converter 1e ... Averaging processing means 2 ... .... Angular velocity sensor 3 ... Travel distance sensor 4 ... GPS receiver 5 ... System controller 6 ... Interface unit 7 ... CPU
8 ... ROM
9 ... RAM
10 .... Bus line 11 .... Input device 12a ... DVD-ROM drive 12b ... CD-ROM drive 13 ... Display unit 14 ... Graphics controller 15 ... ... Buffer memory 16 ... Display control unit 17 ... Display 18 ... Sound reproduction unit 19 ... D / A converter 20 ... Amplifier 21 ... Speaker 22 ... VICS receiver 101 ... Internal chassis or substrate 102 ... Mounting base 103 ... Recess 104 ... Click stop guide

Claims (10)

A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Determining means for determining whether or not the moving body is moving forward;
Setting means for setting the polarity of the output of the first detection unit and the polarity of the output of the second detection unit based on the output of the acceleration detection unit and the determination result of the determination unit;
A navigation system comprising:   The setting means determines the polarity of the output of the first detection section and the output of the second detection section based on the output of the acceleration detection means when the determination means determines that the moving body is moving forward. The navigation system according to claim 1, wherein polarity is set. A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Acquisition means for acquiring GPS positioning data including at least speed information in the mobile body;
Setting means for setting the polarity of the output of the first detection unit and the polarity of the output of the second detection unit based on the output of the acceleration detection unit and the GPS positioning data acquired by the acquisition unit ;
A navigation system comprising: A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Obtaining means for obtaining a vehicle speed pulse of the moving body;
Setting means for setting the polarity of the output of the first detection unit and the polarity of the output of the second detection unit based on the output of the acceleration detection unit and the speed calculated from the vehicle speed pulse ;
A navigation system comprising: A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Setting means for setting a detection unit that detects an acceleration at the time of start of the moving body among the first detection unit and the second detection unit as a detection unit that detects an acceleration in the front-rear direction of the moving body;
A navigation system comprising: A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Display control means for displaying on the display means a plurality of candidates indicating the installation direction of the acceleration detecting means relative to the moving body;
Selecting means for selecting one candidate from a plurality of candidates displayed on the display means;
Setting means for setting the output polarity of the first detection unit and the output polarity of the second detection unit based on the installation direction corresponding to the selected candidate;
A navigation system comprising: A first detector that detects acceleration in the first direction; and a second detector that detects acceleration in a second direction that is 90 ° to the first direction. Acceleration detecting means for detecting the acceleration of the moving body based on the output and the output of the second detection unit;
Display control means for displaying on the display means a plurality of candidates indicating the installation direction of the navigation apparatus body with the acceleration detection means built in the moving body;
Selecting means for selecting one candidate from a plurality of candidates displayed on the display means;
Setting means for setting the output polarity of the first detection unit and the output polarity of the second detection unit based on the installation direction corresponding to the selected candidate;
A navigation system comprising: A polarity setting method for setting respective polarities of an acceleration in a first direction of a moving body and an acceleration in a second direction which is a direction of 90 ° with respect to the first direction,
A determination step of determining whether the moving body is moving forward;
The first direction of the acceleration, the second direction of the acceleration, and on the basis of the determination result of the determining step, the first direction of the acceleration and set to set the polarity of the acceleration of the second direction Process,
A polarity setting method characterized by comprising: The acceleration of the first direction of the moving body, a polarity setting method for setting the respective polarity between said first second direction of acceleration is the direction of 90 ° with respect to the direction,
An acquisition step of acquiring GPS positioning data including at least speed information in the mobile body;
Said first direction of the acceleration, and the second direction of the acceleration, and on the basis of the GPS positioning data, the first direction of the acceleration and the setting process to set the polarity of the acceleration in the second direction ,
A polarity setting method characterized by comprising: The acceleration of the first direction of the moving body, a polarity setting method for setting the respective polarity between said first second direction of acceleration is the direction of 90 ° with respect to the direction,
An acquisition step of acquiring a vehicle speed pulse of the moving body;
Said first direction of the acceleration, and the second direction of the acceleration, and on the basis of the GPS positioning data, the first direction of the acceleration and the setting process to set the polarity of the acceleration in the second direction ,
A polarity setting method characterized by comprising:

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