JP2009229268A - Distance coefficient approximate expression creating device, distance coefficient approximate expression creating method, and distance coefficient approximate expression creating program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance coefficient approximate expression creating device for creating a distance coefficient approximate expression for calculating a distance coefficient with high accuracy as compared with the case using a fixed distance coefficient. <P>SOLUTION: In this distance coefficient approximate expression creating device, a speed acquiring means acquires the travel speed of a moving object, a number-of-pulses acquiring means acquires the vehicle speed pulse when the speed is acquired, and a distance coefficient value calculating means calculates the distance coefficient value using the travel speed and the number of pulses. An information registering means for creating an approximate expression registers the average value of the travel speed and the average value of the distance coefficient value every predetermined speed region, and a creating means creates a distance coefficient approximate expression by the least squares method or the like using the average value of the travel speed and the average value of the distance coefficient value. Thus, the distance coefficient approximate expression creating device can acquire the distance coefficient value responsive to the speed using the speed acquired by a predetermined method and the distance coefficient approximate expression. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for generating an approximate expression of a distance coefficient.

  The relative travel distance of the vehicle is obtained by multiplying the vehicle speed pulse number based on the vehicle speed pulse output by the distance sensor that detects the rotation speed of the wheel by a predetermined distance coefficient value. This distance coefficient value is the travel distance per pulse of the vehicle speed pulse. Since pulses are generated in proportion to the travel distance, the vehicle speed and the number of pulses are proportional, and the distance coefficient value takes a substantially constant value. Therefore, it is assumed that the speed of the vehicle and the number of vehicle speed pulses, which are the characteristics of the data for acquiring the vehicle speed signal from the hard wire as shown in FIG.

  By the way, in recent years, the in-vehicle LAN (Local Area Network) has progressed, and as shown in FIG. 1B, processing is performed based on digitally converted data via an adapter or the like that performs conversion processing for acquiring in-vehicle LAN data. Has been done.

  Depending on the adapter that converts data, an error may occur when digital data is converted or when digital data is converted to an analog voltage. As a result, a situation occurs in which the speed of the vehicle and the number of vehicle speed pulses are not proportional to each other, and there has been a problem that a vehicle using such an adapter has a possibility that an error from an accurate distance becomes large.

  Further, when the vehicle travels, the tire expands due to the centrifugal force according to the speed change, so that the radius of the tire changes, and the travel distance per one pulse of the vehicle speed pulse and the output timing of the vehicle speed pulse change. Therefore, there is a problem that an error occurs in the relative travel distance of the vehicle.

  By the way, there is a navigation device that calculates a relative travel distance using a distance coefficient value corresponding to a speed change of a vehicle by having a plurality of distance coefficient values for each speed range (see, for example, Patent Document 1).

JP 2005-257665 A

  The navigation device described above holds a distance coefficient value for each predetermined speed range. However, the speed that is not measured is not necessarily an appropriate distance coefficient value. When trying to calculate the coefficient value, there is a problem that a load of calculating the distance coefficient is applied.

  Examples of the problems to be solved by the present invention include those described above. An object of the present invention is to provide a distance coefficient approximate expression generation apparatus capable of generating an approximate expression of a distance coefficient capable of calculating a distance coefficient with higher accuracy than when a fixed distance coefficient is used. It is in.

  The invention according to claim 1 is based on speed acquisition means for acquiring the traveling speed of the mobile body, pulse number acquisition means for acquiring the number of pulses when the mobile body travels, and the travel speed and the number of pulses. Distance coefficient value calculating means for calculating the distance coefficient value, registration means for registering the average value of the traveling speed and the average value of the distance coefficient value for each speed range, and the average of the traveling speed for each speed range Generating means for generating a distance coefficient approximate expression using a value and an average value of distance coefficient values.

  The invention according to claim 6 is a distance coefficient approximate expression generation method, a speed acquisition step of acquiring the traveling speed of the moving body, a pulse number acquisition step of acquiring the number of pulses when the moving body travels, A distance coefficient value calculating step of calculating a distance coefficient value based on the traveling speed and the number of pulses, and a registration step of registering an average value of the traveling speed and an average value of the distance coefficient value for each speed range; A generation step of generating a distance coefficient approximate expression using an average value of travel speed and an average value of distance coefficient values for each speed range is provided.

  The invention according to claim 7 is a distance coefficient approximate expression generation program executed by an apparatus including a computer, the speed acquisition means for acquiring the traveling speed of the moving body, and the number of pulses when the moving body travels. A pulse number acquisition means to acquire; a distance coefficient value calculation means to calculate a distance coefficient value based on the travel speed and the pulse number; and an average value of the travel speed and an average of the distance coefficient value for each speed range The computer is caused to function as registration means for registering a value, and generation means for generating a distance coefficient approximate expression using an average value of traveling speed and an average value of distance coefficient values for each speed range, To do.

  In a preferred embodiment of the present invention, the distance coefficient approximate expression generation device includes a speed acquisition unit that acquires a traveling speed of the moving body, a pulse number acquisition unit that acquires a pulse number when the moving body travels, and the traveling Distance coefficient value calculating means for calculating a distance coefficient value based on speed and the number of pulses, registration means for registering the average value of the traveling speed and the average value of the distance coefficient value for each speed range, and speed Generating means for generating a distance coefficient approximate expression using an average value of travel speeds and an average value of distance coefficient values for each region.

  Specifically, the above-described distance coefficient approximate expression generation device can be applied to a navigation device or the like. In the distance coefficient approximate expression generation device, the speed acquisition unit acquires the traveling speed of the moving body, the pulse number acquisition unit acquires the vehicle speed pulse at the time of speed acquisition, and the distance coefficient value calculation unit calculates the travel speed and The distance coefficient value is calculated using the number of pulses.

  And a registration means registers the average value of the said traveling speed and the average value of the said distance coefficient value for every predetermined speed area (for example, 10 km / h), and a production | generation means is the average value of the said traveling speed, A distance coefficient approximate expression is generated by a least square method or the like using the average value of the distance coefficient values.

  As described above, the distance coefficient approximate expression generation apparatus calculates a predetermined speed and a distance coefficient value corresponding to the speed, calculates an average value of the speed and the distance coefficient value for each speed range, and calculates a distance coefficient. By calculating a numerical approximate expression, the correlation between the speed and the distance coefficient value can be defined.

  According to this, the distance coefficient approximate expression generation device can acquire the distance coefficient value corresponding to the speed by substituting the acquired speed into the approximate expression, compared with the case where a fixed distance coefficient value is used. Thus, a more appropriate distance coefficient value can be acquired. Therefore, an accurate travel distance can be calculated by using the distance coefficient value acquired by the distance coefficient approximate expression generation apparatus.

  In one aspect of the above-described distance coefficient approximate expression generation device, the speed acquisition means includes a GPS speed, a speed based on an output of an acceleration sensor that detects an acceleration of the moving body, or a wheel encoder installed on a wheel of the moving body. The speed based on the output is acquired as the traveling speed. In this case, the distance coefficient approximate expression generation device can calculate an approximate expression of the distance coefficient value using a GPS speed, an acceleration sensor, or a wheel encoder. Therefore, the distance coefficient approximate expression generation apparatus can acquire a distance coefficient value corresponding to the speed using the speed acquired by a predetermined method and the approximate expression.

  In another aspect of the distance coefficient approximate expression generation device, the speed acquisition unit acquires a speed obtained by adding a predetermined differential speed to the latest GPS speed as a traveling speed. According to this, the distance coefficient approximate expression generation device calculates the speed of a vehicle or the like equipped with the distance coefficient approximate expression generation device even in a situation where the GPS speed cannot be measured, such as when passing through a tunnel. And an approximate expression of the distance coefficient value can be calculated based on the speed. Therefore, the distance coefficient approximate expression generation apparatus can acquire a distance coefficient value corresponding to the speed using the speed acquired by a predetermined method and the approximate expression.

  In another aspect of the distance coefficient approximation expression generation device, the differential speed is calculated based on a speed based on an output of an acceleration sensor that detects an acceleration of the moving body or an output of a wheel encoder installed on a wheel of the moving body. It is the differential speed obtained from the speed based on it. In this case, the distance coefficient approximate expression generation device can calculate the differential speed using the speed acquired from the acceleration sensor or the wheel encoder.

  In another aspect of the present invention, there is provided a travel distance calculation device equipped with the above-described distance coefficient approximate expression generation device, wherein the travel speed is calculated based on the travel speed acquired by the travel acquisition means and the distance coefficient approximate expression. A setting means for setting a corresponding distance coefficient value; a travel distance calculating means for calculating the travel distance of the moving body based on the number of pulses acquired by the pulse number acquisition means and the distance coefficient value corresponding to the travel speed; Is provided. In this case, the travel distance calculation device calculates an appropriate distance coefficient value corresponding to a change in the radial radius of the tire due to a speed change or the like by calculating a distance coefficient value using the distance coefficient approximation formula. Therefore, an appropriate travel distance can be calculated.

  In another aspect of the present invention, there is provided a distance coefficient approximate expression generation method, a speed acquisition step of acquiring a traveling speed of a mobile body, a pulse number acquisition step of acquiring a pulse number during travel of the mobile body, A distance coefficient value calculating step for calculating a distance coefficient value based on a traveling speed and the number of pulses; a registration step for registering an average value of the traveling speed and an average value of the distance coefficient value for each speed range; A generation step of generating a distance coefficient approximate expression using the average value of the traveling speed and the average value of the distance coefficient value for each speed range is provided.

  Also by such a distance coefficient approximate expression generation method, a predetermined speed and a distance coefficient value corresponding to the speed are calculated, an average value of the speed and the distance coefficient value for each speed range is calculated, and a distance coefficient is calculated. By calculating a numerical approximate expression, the correlation between the speed and the distance coefficient value can be defined. By substituting the acquired speed into the approximate expression, the distance coefficient value corresponding to the speed is acquired. As compared with the case where a fixed distance coefficient value is used, a more appropriate distance coefficient value can be obtained.

  In another aspect of the present invention, a distance coefficient approximate expression generation program executed by a device including a computer, the speed acquisition means for acquiring the traveling speed of the moving body, and the number of pulses when the moving body travels A pulse number acquisition means for performing, a distance coefficient value calculation means for calculating a distance coefficient value based on the travel speed and the pulse number, and an average value of the travel speed and an average value of the distance coefficient value for each speed range The computer is caused to function as a registration means for registering and a generation means for generating a distance coefficient approximation expression using an average value of travel speed and an average value of distance coefficient values for each speed range. By executing such a distance coefficient approximate expression generation program on various devices, the distance coefficient approximate expression generation apparatus of the present invention can be realized. The distance coefficient approximate expression generation program can be suitably handled in a state where it is recorded on a recording medium.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Overview]
The travel distance calculation device in this embodiment is applied to a navigation device described later. The travel distance calculation device defines a speed range in advance (for example, in increments of 10 [km / h]). Then, the travel distance calculation device acquires the GPS speed, acquires the number of vehicle speed pulses when the GPS speed is detected, and calculates a distance coefficient value from the travel distance when the GPS speed is detected and the number of vehicle speed pulses.

  The travel distance calculation device calculates the average value of the GPS speed and the average value of the distance coefficient value for each speed range, and holds the average value of the GPS speed and the average value of the distance coefficient value. deep.

  Then, after calculating the distance coefficient value for a predetermined number of times, the travel distance calculating device generates a distance coefficient approximate expression by the least square method using the average value of the distance coefficient values in each speed range and the average speed. .

  As described above, the travel distance calculation apparatus uses the distance coefficient approximation formula as described above even in a situation where the vehicle speed and the number of vehicle speed pulses are not proportional, such as when the distance per pulse changes due to a speed change or the like. For example, since the distance coefficient corresponding to each speed can be calculated, the travel distance of the vehicle can be calculated appropriately.

[Navigation device]
FIG. 2 shows the configuration of the navigation apparatus 200 according to the embodiment of the present invention. As shown in FIG. 2, the navigation device 200 includes a self-supporting positioning device 10, a GPS receiver 18, a system controller 20, a disk drive 31, a data storage unit 36, a communication interface 37, a communication device 38, a display unit 40, and a voice output. A unit 50 and an input device 60 are provided.

  The autonomous positioning device 10 includes an acceleration sensor 11, an angular velocity sensor 12, and a distance sensor 13. The acceleration sensor 11 is made of, for example, a piezoelectric element, detects vehicle acceleration, and outputs acceleration data. The angular velocity sensor 12 is composed of, for example, a vibrating gyroscope, detects the angular velocity of the vehicle when the direction of the vehicle is changed, and outputs angular velocity data and relative azimuth data. The distance sensor 13 measures a vehicle speed pulse composed of a pulse signal generated with the rotation of the vehicle wheel.

  The GPS receiver 18 receives radio waves 19 including positioning data from a plurality of GPS satellites. Latitude and longitude information obtained using the positioning data is used to detect the absolute position of the vehicle.

  The system controller 20 includes an interface 21, a CPU (Central Processing Unit) 22, a ROM (Read Only Memory) 23, and a RAM (Random Access Memory) 24, and controls the entire navigation apparatus 200.

  The interface 21 performs an interface operation with the acceleration sensor 11, the angular velocity sensor 12, the distance sensor 13, and the GPS receiver 18. From these, vehicle speed pulses, acceleration data, relative azimuth data, angular velocity data, GPS positioning data, absolute azimuth data, and the like are input to the system controller 20. The CPU 22 controls the entire system controller 20. The ROM 23 includes a nonvolatile memory (not shown) in which a control program for controlling the system controller 20 is stored. The RAM 24 stores various data such as route data preset by the user via the input device 60 so as to be readable, and provides a working area to the CPU 22.

  A system controller 20, a disk drive 31 such as a CD-ROM drive or a DVD-ROM drive, a data storage unit 36, a communication interface 37, a display unit 40, an audio output unit 50, and an input device 60 are mutually connected via a bus line 30. It is connected to the.

  The disk drive 31 reads and outputs content data such as music data and video data from a disk 33 such as a CD or DVD under the control of the system controller 20. The disk drive 31 may be either a CD-ROM drive or a DVD-ROM drive, may be a CD and DVD compatible drive, or may be a hard disk recorder with a built-in TV tuner.

  The data storage unit 36 is composed of, for example, an HDD and stores various data used for navigation processing such as map data and facility data.

  The communication device 38 includes, for example, an FM tuner, a beacon receiver, a mobile phone, a dedicated communication card, and the like, and traffic congestion and traffic information distributed from a VICS (Vehicle Information Communication System) center via the communication interface 37. Road traffic information or various information (for example, weather information) from a predetermined server.

  The display unit 40 displays various display data on a display device such as a display under the control of the system controller 20. Specifically, the system controller 20 reads map data from the data storage unit 36. The display unit 40 displays the map data read from the data storage unit 36 by the system controller 20 on a display screen such as a display. The display unit 40 includes a graphic controller 41 that controls the entire display unit 40 based on control data sent from the CPU 22 via the bus line 30 and a memory such as a VRAM (Video RAM), and can display image information that can be displayed immediately. A buffer memory 42 that temporarily stores, a display control unit 43 that controls display of a display 44 such as a liquid crystal display or a CRT (Cathode Ray Tube) based on image data output from the graphic controller 41, and a display 44 are provided. . The display 44 is composed of, for example, a liquid crystal display device having a diagonal of about 5 to 10 inches, and is mounted near the front panel in the vehicle.

  The audio output unit 50 is a D / A converter 51 that performs D / A (Digital to Analog) conversion of audio digital data sent from the disk drive 31 or the RAM 24 via the bus line 30 under the control of the system controller 20. And an amplifier (AMP) 52 that amplifies the audio analog signal output from the D / A converter 51, and a speaker 53 that converts the amplified audio analog signal into audio and outputs the audio into the vehicle. .

  The input device 60 includes keys, switches, buttons, a remote controller, a voice input device, and the like for inputting various commands and data. The input device 60 is disposed around the front panel and the display 44 of the main body of the in-vehicle electronic system mounted in the vehicle. When the display 44 is a touch panel system, the touch panel provided on the display screen of the display 44 also functions as the input device 60.

[Mileage calculation device]
FIG. 3 shows a functional configuration of the travel distance calculation device 300. The travel distance calculation device 300 is substantially composed of the components of the navigation device 200. The mileage calculation device 300 includes a self-supporting positioning device 10, a GPS receiver 18, a system controller 20, and a data storage unit 36 as shown in the figure. The data storage unit 36 stores various information such as the map information DB 120. The system controller 20 includes a speed acquisition unit 101, a pulse number acquisition unit 102, a distance coefficient value calculation unit 103, a registration unit 104, a generation unit 105, a setting unit 106, and a travel distance calculation unit 107. That is, when the system controller 20 executes a predetermined program, the speed acquisition unit 101, the pulse number acquisition unit 102, the distance coefficient value calculation unit 103, the registration unit 104, the generation unit 105, and the setting unit 106 The travel distance calculation unit 107 is realized. The map information DB 120 is a database that holds map information.

  The speed acquisition unit 101 acquires the GPS speed for a predetermined period via the GPS receiver 18. And the pulse number acquisition part 102 acquires the pulse number in the driving | running | working period from which the speed acquisition part 101 was acquiring speed via the distance sensor 13 in the self-supporting positioning apparatus 10. FIG.

  The distance coefficient value calculation unit 103 calculates a distance using the speed acquired by the speed acquisition unit 101 and the travel period during which the GPS speed was acquired, and the distance and the number of pulses in the travel period. Is used to calculate the distance coefficient value.

  Although the distance coefficient value calculation unit 103 calculates the distance based on the speed acquired as described above and calculates the distance coefficient value using the distance, the present invention is not limited to this. Without reference to the map information DB 120, the speed acquisition unit 101 calculates the distance from the speed acquisition start position to the end position based on the GPS positioning information (latitude / longitude information) acquired via the GPS receiver 18, The distance coefficient value may be calculated using the distance.

  The registration unit 104 uses the speed acquired by the speed acquisition unit 101 and the distance coefficient value calculated by the distance coefficient calculation unit 103 to calculate the average speed of the speed and the distance coefficient value for each speed range. The average distance coefficient value is registered as approximate expression generation information.

  Specifically, the registration unit 104 identifies a speed range corresponding to the speed acquired by the speed acquisition unit 101, and based on the registered average speed in the speed range and the speed acquired by the speed acquisition unit 101. Recalculate the average speed.

  Then, the registration unit 104 recalculates the average distance coefficient value using the distance coefficient value calculated by the distance coefficient value calculation unit 103 and the registered average distance coefficient value corresponding to the speed range.

  Then, the average speed and the average distance coefficient value recalculated by the registration unit 104 are updated and registered as the average speed and average distance coefficient value in the speed range.

  The generation unit 105 generates an approximate expression using the approximate expression generation information (average speed, average distance coefficient value) registered by the registration unit 104. Specifically, the generation unit 105 calculates the approximate expression by the least square method using the approximate expression generation information in each speed range.

  After the generation unit 105 generates the approximate expression, the setting unit 106 sets a distance coefficient value corresponding to the GPS speed acquired by the speed acquisition unit 101 using the approximate expression.

  The travel distance calculation unit 107 calculates a travel distance using the distance coefficient value set by the setting unit 106 and the number of pulses at the time of GPS speed measurement.

  Note that the travel distance calculation device 300 in this embodiment also functions as a distance coefficient approximate expression generation device.

[Approximation formula generation method]
Next, an approximate expression generation method according to the present embodiment will be described. In the present embodiment, the approximate expression generation method is to acquire a speed, calculate a distance coefficient value at the time of acquiring the speed, average the acquired speed and distance coefficient value for each speed range, and average the speed And the distance coefficient value are used to generate an approximate expression by the method of least squares.

  First, the speed acquisition unit 101 acquires the GPS speed, and the pulse number acquisition unit 102 acquires the number of pulses when the speed acquisition unit 101 has acquired the GPS speed.

  The distance coefficient value calculation unit 103 calculates a distance coefficient value using the distance in the period during which the speed acquisition unit 101 has acquired the speed and the number of pulses acquired by the pulse number acquisition unit 102.

  The registration unit 104 updates the average speed using the speed acquired by the speed acquisition unit 101 for the registered average speed in the speed range corresponding to the speed acquired by the speed acquisition unit 101. In addition, the registration unit 104 uses the distance coefficient value calculated by the distance coefficient value calculation unit 103 to calculate the average distance coefficient value for the registered average distance coefficient value in the speed range corresponding to the speed acquired by the speed acquisition unit 101. Update. Then, the registration unit 104 updates and registers the updated average speed and the updated average distance coefficient value.

  Then, the registration unit 104 increments the distance coefficient value calculation count for the speed range corresponding to the speed acquired by the speed acquisition unit 101.

  Then, as a result of referring to the distance coefficient value calculation count in each speed range, the generation unit 105 determines that the average speed in each speed range is equal to or greater than the predetermined speed (for example, 50 times). An approximate expression is calculated by the least square method using the average distance coefficient value.

  As described above, the travel distance calculation device 300 acquires the distance and the number of pulses at the time of speed measurement, calculates the distance coefficient value using the distance and the number of pulses, and measures the distance for each predefined speed range. The average speed of the speed and the average distance coefficient value are updated and registered, and an approximate expression defining the correlation between the speed and the distance coefficient value is calculated using the registered average speed and average distance coefficient value.

  According to this, the travel distance calculation device 300 can acquire the distance coefficient value corresponding to the speed by substituting the acquired speed into the approximate expression, as compared with the case where the fixed distance coefficient value is used. A more appropriate distance coefficient value can be acquired.

  Therefore, the travel distance calculation device 300 uses the distance coefficient approximation formula as described above even in a situation where the vehicle speed and the number of vehicle speed pulses are not proportional, such as when the distance per pulse changes due to a speed change or the like. Since the distance coefficient corresponding to each speed can be calculated, the travel distance of the vehicle can be calculated appropriately.

[Distance coefficient approximate expression generation processing]
Hereinafter, the procedure of the distance coefficient approximate expression generation process will be described with reference to the flowchart shown in FIG. This process is realized by the system controller 20 of the travel distance calculation apparatus 300 executing a program prepared in advance.

  First, the speed acquisition unit 101 determines whether or not the GPS speed can be acquired (step S1), and when it is determined that there is no danger such as multipath and the positioning information can be acquired from the GPS (step S1). ; Yes), the GPS speed is acquired (step S2).

  And the pulse number acquisition part 102 acquires the pulse number while the said speed acquisition part 101 was acquiring GPS speed (step S3).

  Then, the distance coefficient value calculation unit 103 calculates a distance coefficient value using the distance in the period during which the speed acquisition unit 101 has acquired the GPS speed and the number of pulses acquired by the pulse number acquisition unit 102 ( Step S4).

  And the registration part 104 updates the said average speed using the GPS speed which the speed acquisition part 101 acquired about the registered average speed in the speed area corresponding to the speed which the speed acquisition part 101 acquired. In addition, the registration unit 104 uses the distance coefficient value calculated by the distance coefficient value calculation unit 103 to calculate the average distance coefficient value for the registered average distance coefficient value in the speed range corresponding to the speed acquired by the speed acquisition unit 101. Update. Then, the registration unit 104 updates and registers the updated average speed and the updated average distance coefficient value (step S5).

  Then, the registration unit 104 increments the distance coefficient value calculation count for the speed range corresponding to the speed acquired by the speed acquisition unit 101 (step S6).

  When the distance coefficient value calculation count is equal to or greater than the threshold as a result of referring to the distance coefficient value calculation count of each speed range, the generation unit 105 determines the average speed and the average distance coefficient value in each speed range. Is used to calculate an approximate expression by the least square method (step S8). After the generation unit 105 generates the approximate expression, the approximate expression generation process ends.

[Approximation formula mileage calculation processing]
Below, the procedure of the approximate expression corresponding travel distance calculation process will be described with reference to the flowchart shown in FIG. This process is realized by the system controller 20 of the travel distance calculation apparatus 300 executing a program prepared in advance. Further, the approximate expression corresponding travel distance calculation process refers to a process of calculating a travel distance using the approximate expression generated by the generation unit 105.

  First, the speed acquisition unit 101 acquires the GPS speed (step S11), and the pulse number acquisition unit 102 acquires the number of pulses in the period acquired by the speed acquisition unit 101 (step S12).

  Then, the setting unit 106 determines whether or not the approximate expression is registered (step S13). When the approximate expression is not registered (step S13; No), the setting unit 106 corresponds to the GPS speed acquired by the speed acquisition unit 101. The registered distance coefficient value of the speed range to be used is set as the distance coefficient value for calculating the travel distance (step S14).

  When the approximate expression is registered (step S13; Yes), the setting unit 106 uses the approximate expression to calculate the travel distance calculation distance corresponding to the travel speed (GPS speed) acquired by the speed acquisition unit 101. A coefficient value is calculated (step S15).

  Then, the travel distance calculation unit 107 calculates the travel distance by multiplying the pulse number acquired by the pulse number acquisition unit 102 by the distance coefficient value set by the setting unit 106 (step S16), and the approximate equation corresponding travel The distance calculation process ends.

  In this way, if the approximate expression exists, the travel distance calculation device 300 calculates the distance coefficient value using the approximate expression. Therefore, even if the tire radial radius changes due to a speed change or the like. A distance coefficient value corresponding to the travel speed can be calculated, and an appropriate travel distance can be calculated using the distance coefficient value.

  Further, since the travel distance calculation device 300 calculates an appropriate travel distance using the above approximate expression, it is possible to calculate an accurate travel speed.

  As described above, the travel distance calculation device 300 includes the speed acquisition unit that acquires the travel speed of the moving body, the pulse number acquisition unit that acquires the pulse number when the mobile body travels, the travel speed and the pulse number. Distance coefficient value calculating means for calculating a distance coefficient value based on the above, registration means for registering the average value of the traveling speed and the average value of the distance coefficient value for each speed range, and the average of the traveling speed for each speed range Generating means for generating a distance coefficient approximate expression using the value and the average value of the distance coefficient values.

  The travel distance calculation device 300 can acquire the distance coefficient value corresponding to the speed by substituting the acquired speed into the approximate expression, and is more appropriate distance than when a fixed distance coefficient value is used. The coefficient value can be acquired.

  In addition, the travel distance calculation apparatus 300 can calculate a distance closer to the true value than the distance calculated from one distance coefficient by using a distance coefficient corresponding to the speed. The travel distance calculation device 300 can recognize the characteristic that the number of vehicle speed pulses is not proportional to the vehicle speed, and can therefore be used when correcting the distance. Furthermore, the travel distance calculation apparatus 300 can perform classification according to a tendency among non-proportional characteristics from an approximate function obtained from a plurality of distance coefficient values, which is useful for distance correction and the like.

  Further, the travel distance calculation apparatus 300 can grasp the change state of the dynamic radius of the tire from an approximate function obtained from a plurality of distance coefficient values even for a vehicle in which the number of vehicle speed pulses is proportional to the vehicle speed. Compared to the case where a fixed distance coefficient value is used, a distance coefficient value with higher accuracy can be obtained. As a result, the travel distance calculation device 300 can perform navigation with higher positional accuracy for both a vehicle in which the number of vehicle speed pulses is proportional to the vehicle speed and a vehicle in which the number of vehicle speed pulses, which has been increasing in recent years, is not proportional to the vehicle speed. Can be provided.

  Further, the distance coefficient approximate expression generation apparatus 300 can classify the characteristics for each tendency from the approximate function obtained from a plurality of distance coefficient values. As described above, since the distance coefficient approximate expression generation apparatus 300 obtains the classification result, the user of the distance coefficient approximate expression generation apparatus 300 can grasp the tendency of characteristics based on the type of adapter.

[Other embodiments]
In the above-described embodiment, the case where the speed acquisition unit 101 can receive GPS data via the GPS receiver 18 has been described. However, even when GPS data cannot be received, an approximate expression is obtained using the GPS speed acquired in the past. You can respond by substituting. As a specific example, a speed calculation method is shown below.

  (Procedure 1) The speed acquisition unit 101 calculates the approximate sensor speed S1 using the latest distance coefficient value among the previously calculated distance coefficient values.

  (Procedure 2) When the approximate sensor speed S0 calculated last time exists, the speed acquisition unit 101 calculates a difference between S1 and S0 and adds the difference to the speed difference D.

  (Procedure 3) The speed acquisition unit 101 adds the speed difference D to the reference GPS speed (the latest past GPS speed used for calculating the approximate distance coefficient value) to obtain the speed S to be substituted into the approximate expression.

  If the speed acquisition unit 101 acquires the speed according to the above (procedure 1) to (procedure 3), it is possible to calculate the distance coefficient value even in a situation where the GPS speed cannot be acquired.

  The speed acquisition unit 101 calculates the speed S and then stores the approximate sensor speed S1 as S0. Further, the speed acquisition unit 101 calculates the approximate sensor speed based on the distance coefficient value and calculates the differential speed, but the speed based on the output of the measured acceleration sensor after the GPS speed cannot be acquired has been described. Or you may make it measure a differential speed | rate based on the speed based on the output of the wheel encoder installed in the wheel of a mobile body. For example, after the GPS speed cannot be acquired, the speed acquisition unit 101 calculates the amount of change between the speed obtained by the wheel encoder and the speed obtained by the latest wheel encoder, and acquires the amount of change and the GPS speed. A differential speed is calculated based on the elapsed time since it was not possible, and the speed of the vehicle is calculated using the differential speed and the latest GPS speed.

  In the above-described embodiments, the case where the generation unit 105 generates an approximate expression using the least square method has been described. However, the present invention is not limited to this, and the approximate expression is generated by various other methods. May be.

  Although not specifically described in the above-described embodiment, when the vehicle to be mounted is specified, the vehicle speed pulse characteristic and the tire dynamic radius characteristic of the vehicle to be mounted are investigated in advance and The based distance coefficient value may be used as an initial value of the distance coefficient value for each speed range of the travel distance calculation device 300.

  Although not specifically described in the above-described embodiment, the travel distance calculation device 300 uses the distance coefficient value calculated by the distance coefficient value calculation unit 103 and the like, and the characteristics of the obtained vehicle speed cycle are not the same as those of the navigation device. When it is detected that matching frequently occurs, error information may be saved as log information or displayed on the display device 40.

  In the above-described embodiment, the case where the speed acquisition unit 101 acquires the GPS speed via the GPS receiver 18 has been described. However, the present invention is not limited to this, and the output of the acceleration sensor that detects the acceleration of the moving body is used. The speed based on the speed based on the output of a wheel encoder installed on the wheel of the moving body or the moving body may be acquired as the traveling speed, or the speed obtained by various other methods may be acquired.

It is a conceptual diagram of the acquisition method of a vehicle speed pulse. It is a block diagram which shows schematic structure of a navigation apparatus. It is a functional block diagram of a mileage calculation device. It is a flowchart of a distance coefficient approximate expression generation process. It is a flowchart of an approximate expression corresponding travel distance calculation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Autonomous positioning apparatus 18 GPS receiver 20 System controller 36 Data storage unit 101 Speed acquisition part 102 Pulse number acquisition part 103 Distance coefficient value calculation part 104 Registration part 105 Generation part 106 Setting part 107 Travel distance calculation part 120 Map information DB
200 navigation device 300 mileage calculation device

Claims (8)

Speed acquisition means for acquiring the traveling speed of the moving body;
Pulse number acquisition means for acquiring the number of pulses during travel of the moving body;
Distance coefficient value calculating means for calculating a distance coefficient value based on the travel speed and the number of pulses;
Registration means for registering the average value of the traveling speed and the average value of the distance coefficient value for each speed range;
Generating means for generating a distance coefficient approximate expression using an average value of travel speed and an average value of distance coefficient values for each speed range;
A distance coefficient approximate expression generation apparatus comprising:   The speed acquisition means acquires a GPS speed, a speed based on an output of an acceleration sensor that detects acceleration of the moving body, or a speed based on an output of a wheel encoder installed on a wheel of the moving body as a traveling speed. The distance coefficient approximate expression generation apparatus according to claim 1.   The distance coefficient approximate expression generation apparatus according to claim 1, wherein the speed acquisition unit acquires a speed obtained by adding a predetermined differential speed to the latest GPS speed as a traveling speed.   The differential speed is a differential speed acquired from a speed based on an output of an acceleration sensor that detects an acceleration of the moving body or a speed based on an output of a wheel encoder installed on a wheel of the moving body. Item 4. The distance coefficient approximate expression generation device according to Item 3. A travel distance calculation device equipped with the distance coefficient approximate expression generation device according to any one of claims 1 to 4,
Setting means for setting a distance coefficient value corresponding to the travel speed based on the travel speed acquired by the travel acquisition means and the distance coefficient approximate expression;
A travel distance calculating means for calculating the travel distance of the moving body based on the number of pulses acquired by the pulse number acquiring means and a distance coefficient value corresponding to the travel speed;
A mileage calculating device comprising: A speed acquisition step for acquiring the traveling speed of the moving body;
A pulse number acquisition step of acquiring the number of pulses during travel of the moving body;
A distance coefficient value calculating step of calculating a distance coefficient value based on the travel speed and the number of pulses;
A registration step of registering an average value of the traveling speed and an average value of the distance coefficient value for each speed range;
A generation step for generating a distance coefficient approximate expression using an average value of travel speed and an average value of distance coefficient values for each speed range;
A distance coefficient approximate expression generation method comprising: A distance coefficient approximate expression generation program executed by an apparatus including a computer,
Speed acquisition means for acquiring the traveling speed of the moving body;
Pulse number acquisition means for acquiring the number of pulses during travel of the moving body;
Distance coefficient value calculating means for calculating a distance coefficient value based on the travel speed and the number of pulses;
Registration means for registering the average value of the traveling speed and the average value of the distance coefficient value for each speed range;
A distance coefficient approximate expression generation program that causes the computer to function as a generating means for generating a distance coefficient approximate expression using an average value of travel speed and an average value of distance coefficient values for each speed range.   A recording medium on which the distance coefficient approximate expression generation program according to claim 7 is recorded.

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