JP4273052B2 - Moving distance deriving method and apparatus - Google Patents

Description

  The present invention relates to a moving distance deriving method and apparatus for measuring and deriving a moving distance in a moving body such as a vehicle by using a method of receiving and measuring a positioning radio wave and a method of measuring independently. Belonging to the field.

  Currently, for example, as a positioning device for various moving objects such as automobiles, airplanes, ships, etc., a position mark indicating the position of the moving object is superimposed on the point on the map including the point where the moving object currently exists There is known a so-called navigation device that displays information and guides a route to a destination based on the displayed information. Among these navigation devices, vehicle navigation devices mounted on a vehicle are roughly classified into a self-supporting navigation device and a GPS (Global Positioning System) type navigation device.

  The former calculates the moving direction and moving distance of the moving body by the speed sensor and the angular velocity sensor provided in the moving body, calculates the current position by adding it to the reference point, and displays based on the calculated current position. A position mark and a corresponding map are displayed on the screen.

  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.

  More recently, so-called hybrid type vehicle navigation devices having both the above-described functions of the self-supporting type and the GPS type are becoming common.

  According to each of the vehicle navigation devices described above, the user (driver) can be ascertained by associating his / her current position with a map in the vicinity of the current position. You can reach your destination without any problems.

  On the other hand, in the vehicle navigation device, as a method of calculating the moving distance of the moving body, in addition to the method of calculating based on the positioning radio wave, a pulse signal output based on rotation of the tire (that is, rotation of the axle) (Having a predetermined number of pulses for one rotation of the tire), the moving speed (km / h) measured using the positioning radio wave is converted into a second speed, and the converted second speed is generated in one second. The movement distance per pulse (m / pulse) (hereinafter referred to as unit movement distance) is calculated by dividing by the number of pulses of the pulse signal, and the total pulses detected during the movement within the calculated unit movement distance. There is a method of calculating the movement distance autonomously by multiplying by a number.

  Here, as the accuracy in calculating the actual moving distance, the moving distance calculated based on the positioning radio wave is the number of GPS satellites that can be used for positioning and the reception status of the positioning radio wave depending on the surroundings of the position where the moving object exists It is not always possible to calculate the travel distance with high accuracy due to changes in the location, etc., and if the mobile object moves to a location where the positioning radio wave does not reach, such as a tunnel, the positioning radio wave is received again. The distance moved up to may not be added, and the error often increases. Therefore, in particular, in the hybrid type vehicle navigation apparatus, the unit moving distance is normally maintained while being updated, and the unit moves based on the unit moving distance and the number of pulses in the pulse signal generated along with the movement. The distance is calculated. Then, if necessary, the held unit movement distance is corrected based on the positioning radio wave, and the movement distance is calculated.

  As described above, the movement distance calculated autonomously using the constantly updated unit movement distance is corrected with the movement distance calculated by the positioning radio wave, so that the movement distance of the moving body can be obtained more accurately. it can.

  However, in the calculation of the movement distance based on the pulse signal, the unit movement distance varies depending on the change in the movement state of the moving body. Therefore, when the movement state changes, the movement distance may not be accurately calculated. There was a problem.

  The error in the movement distance due to the change in the movement state will be explained by taking the case where the moving body is a vehicle as an example.For example, when driving in the winter, if the summer tire is replaced with the winter tire, the summer tire and the winter Because the tire diameter and air pressure of the tires differ, the unit travel distance will inevitably differ, but at this time, it was replaced with a winter tire based on the unit travel distance calculated based on the summer tire. When the unit travel distance is updated by the above update process, the unit travel distance is greatly different between the summer tire and the winter tire, so that unnecessary time is required for the update, and a unit travel distance suitable for the winter tire can be obtained. Until then, there was a first problem that the error of the unit moving distance was large and the correct moving distance could not be calculated.

  In addition, even if a unit travel distance suitable for the winter tire is obtained after replacing it with a winter tire, if the travel state changes by temporarily attaching a chain or slipping, Despite the fact that the chain is attached or slipped is a short-term phenomenon, the unit travel distance will be updated based on the chain attached or slipped, so if the chain is removed or after the slip stops In the second case, the unit travel distance changes discontinuously, and until the unit travel distance suitable for the original winter tire is obtained again, the error of the unit travel distance is large and the correct travel distance cannot be calculated. There was a problem.

  Further, considering the case where the vehicle is moving backward, normally, when the vehicle is moving backward, a reverse signal (a signal for turning on the backup lamp) indicating that the vehicle is moving backward is generated by setting the transmission to reverse. However, in the conventional vehicle navigation apparatus, the logical level of the reverse signal (generally “H” during reverse) is monitored, and the moving distance of the vehicle when this is “H” is The travel distance on the vehicle navigation device (the travel distance when moving forward) is not added. However, in a vehicle navigation device that should be applicable to a plurality of types of vehicles, for example, for a vehicle that generates a reverse signal that is “L” during reverse travel, the movement of the vehicle when the reverse signal is “L” Since it is necessary to configure such that the distance is not added to the moving distance on the vehicle navigation device, the conventional vehicle navigation device (the moving distance when the logical level of the reverse signal is “H” is used as the vehicle navigation device). In this case, it cannot be applied to a vehicle that generates a reverse signal that is “L” during reverse travel, and the travel distance during reverse travel is added to the travel distance during forward travel. There was a third problem that the error of the above becomes large.

  Furthermore, in a vehicle navigation device that should be applicable to a plurality of types of vehicles, conventionally, an LPF for removing noise in a high frequency band in the pulse signal is provided. For example, if the LPF frequency band is set so as to adapt to a vehicle having a high number of pulses output per axle revolution, the number of pulses output per axle revolution is output. Based on the pulse signal on which the noise is superimposed, the noise in the high frequency circumferential band in the vehicle having a low pulse number cannot be substantially removed, and the noise is superimposed on the pulse signal in the vehicle having the low pulse number. Thus, there is a fourth problem that the error of the movement distance increases when the movement distance is calculated.

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that even if the moving state of the moving body changes or the mounted vehicle itself changes, the movement can be made accurately. It is an object to provide a moving distance deriving method and apparatus capable of deriving a distance.

In order to solve the above-mentioned problem, the invention according to claim 1 is a measuring means for measuring the moving speed of a moving body, and whether or not the measured moving speed is equal to or higher than a preset set speed. determining means for determining, detecting means for detecting the logic level of the signal to turn on the backup lamp of the movable body at every predetermined timing, by the detection means when the moving speed was set speed or more the detected the logic levels, comprising storage means for storing a logic level at the time of forward movement of the movable body, and a calculating means for calculating a moving distance at the time of forward movement of the movable body, said calculation means, said detection If the logic level detected by the means is a logic level different from the level at the time of the forward stored in the storage means, as the moving body is retracted, those Characterized in that it does not counted a moving distance at the time of retreat the moving distance at the time of the forward.

The invention according to claim 2 is a measuring step of measuring the moving speed of the moving body, a determining step of determining whether or not the measured moving speed is equal to or higher than a preset set speed, and the moving a detection step of detecting the logic level of the signal to turn on the backup lamp body at every predetermined timing, the detected said logic level when the moving speed was set speed or more, of the movable body A storage step of storing as a logical level at the time of forward movement, and a calculation step of calculating a moving distance at the time of forward movement of the moving body. In the calculation step, the detected logical level is stored as the logical level. a logical level different from the level at the time of the forward who is, as the moving body is retracted, moving distance of the moving distance at the time of the backward during the forward Characterized in that it shall not be included in.

Next, preferred embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, a case where the present invention is applied to a vehicle navigation apparatus in an automobile or the like will be described.
(I) Device Configuration First, the overall configuration of the vehicle navigation device of the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the vehicle navigation apparatus S according to the embodiment detects an angular velocity at the time of direction change of the own vehicle, outputs angular velocity data and relative bearing data, and rotates the wheel. The unit travel distance is calculated by counting the number of pulses in the output pulse signal, and is output as distance data _SD to a CPU 6 (described later) via a bus line 9 (described later). Based on the GPS receiver 3 that receives radio waves and outputs GPS positioning data and outputs absolute direction data of the traveling direction of the vehicle, and relative direction data, angular velocity data, travel distance data, GPS positioning data, and absolute direction data System controller 4 for controlling the entire navigation device, remote control device for inputting various data, etc. The CD-ROM drive 11 reads and outputs various data such as road data including the number of lanes and road width from a CD-ROM (Compact Disk Read Only Memory) disk DK under the control of the input device 10 and the system controller 4. And a display unit 12 that displays various display data under the control of the system controller 4 and a sound reproduction unit 17 that reproduces and outputs various audio data under the control of the system controller 4. .

  The system controller 4 includes an interface unit 5 that performs an interface operation with an external sensor such as the GPS receiver 3, a CPU 6 that controls the entire system controller 4, and a ROM (a control program that controls the system controller 4). Read Only Memory) 7 and a RAM 8 having a nonvolatile memory (not shown) and the like, and storing various data such as route data preset by the user via the input device 10 in a readable manner. The apparatus 10, the CD-ROM drive 11, the display unit 12 and the sound reproduction unit 17 are connected via a bus line 9.

  Further, the display unit 12 includes a graphic controller 13 that controls the entire display unit 12 based on control data sent from the CPU 6 via the bus line 9, and a memory such as a VRAM (Video RAM), and can be displayed immediately. A buffer memory 14 that temporarily stores image information; and a display control unit 15 that controls display of a display 16 such as a liquid crystal display or a CRT (Cathode Ray Tube) based on image data output from the graphic controller 13. Configured.

  The sound reproducing unit 17 outputs a D / A converter 18 that performs D / A conversion of audio digital data sent from the CD-ROM drive 11 or the RAM 8 via the bus line 9, and is output from the D / A converter 18. An amplifier 19 that amplifies the audio analog signal and a speaker 20 that converts the amplified audio analog signal into audio and outputs the audio are configured.

In the above configuration, the distance data _SD is output from the travel distance sensor 2 to the CPU 6 between the travel distance sensor 2 and the CPU 6, and the GPS acquired from the GPS sensor 3 is transmitted from the CPU 6 to the travel distance sensor 2. RAM switching for switching the plurality of output signals from a plurality of RAM in the travel distance sensor 2 described later based on the switching information input from the GPS velocity data S _G and the input device 10 calculated in CPU6 based on the positioning data signal _{S C} is output.

  Next, the structure of the mileage sensor 2 which is the characteristic of this invention is demonstrated using FIG.

As shown in FIG. 2, the travel distance sensor 2, a LPF for removing noise from the pulse signal S _P which is output with the rotation of the axle of the vehicle navigation apparatus S is equipped with, in LPF for removing with the pulse signal high pulse number for LPF30 for removing noise of a high frequency region in the S _P when the number of pulses per axle revolution of the pulse signal S _P is large, the noise from the pulse signal S _P there are, the pulse signal S and the low number of pulses for LPF31 for removing noise of a high frequency region in the pulse signal S _P when a small number of pulses of the axle revolution every _P, the switch control signal S from the sub CPU34 below Based on _SW , switches 32 and 33 for switching the LPF 30 for the high pulse number and the LPF 31 for the low pulse number; It controls the whole based on the GPS velocity data _{S G} and RAM switching signal _{S C} from the CPU6, sub CPU34 outputs the CPU6 distance data _{S D} by performing the processing shown in the flowchart described later, in the summer tires The RAM 35 temporarily stores and outputs the corresponding unit moving distance, and the RAM 36 temporarily stores and outputs the unit moving distance corresponding to the winter tire. The sub CPU 34 includes a counter 34C that counts the number n of times the unit moving distance is updated.

1 and 2, the CPU 6 included in the system controller 4 functions as a speed calculation unit and a selection unit, and the sub CPU 34 in the travel distance sensor 2 calculates a calculation unit, a derivation unit, a distance calculation unit, and an error calculation. Functions as a means, a coefficient updating means, a measuring means, a determining means, a deriving means, and a detecting means. Further, the RAMs 35 and 36 function as storage means.
(II) Operation Next, the operation of the vehicle navigation device S according to the present invention will be described.

  The operations shown in the following flowcharts are mainly executed by the sub CPU 34 and the CPU 6 and are executed as part of a main navigation program for controlling the entire vehicle navigation device S and executing a navigation operation. Therefore, during the execution of the main navigation program, the operation shown in the flowchart of the embodiment is always executed.

  A program corresponding to the flowcharts in the following embodiments is stored in advance in the ROM 7 or a ROM (not shown) in the sub CPU 34 as a control program, and is read out as necessary.

  Further, before the travel distance calculation process shown in FIG. 3 is performed, it is determined whether the vehicle equipped with the vehicle navigation device S is equipped with a summer tire or a winter tire. 10 is set in advance and stored in a RAM (not shown) in the sub CPU 34.

First, the entire processing of calculating the movement distance in the sub CPU 34 will be described with reference to the flowchart shown in FIG. The process shown in the flowchart shown in FIG. 3 is executed at a rate of about once per second, and the movement distance is calculated and output as distance data _SD .

As shown in FIG. 3, in the movement distance calculation process, first, when the ignition switch of the vehicle is turned on, the counter 34C is initialized (more specifically, the count value is set to “0”). (Step S1). When the initialization is completed (step S1), the process proceeds to a converged unit movement distance switching routine which will be described later (step S2). The unit travel distance switching routine in step S2 is pre-calculated and converged in the vicinity of the target value. The unit travel distance corresponding to the summer tire stored in the RAM 35 is pre-calculated and converged in the vicinity of the target value. a process for obtaining by switching based on the RAM switching signal S _C of the unit travel distance corresponding to the winter tire which is stored in the RAM36 from CPU6 state. Details of the unit movement distance switching routine and the unit movement distance convergence operation will be described later.

When the unit movement distance switching routine ends (step S2), it is next determined whether or not the value of the counter 34C is “0” (step S3). Then, when the value of the counter 34C is not "0" (step S3; NO), by multiplying the number of pulses of the pulse signal S _P in the time to be measured moving distance with respect to the value of the most recent unit movement distance Then, the movement distance at the time to be measured is calculated (step S4), and is output as distance data _SD to the CPU 6 via the bus line 9, and the process proceeds to step S5. At this time, if the logical level of the reverse signal is a logical level determined to be reverse in a forward / reverse logical automatic determination routine in step S10 described later, the movement distance at that time is not added. I do.

On the other hand, in the process at the step S3, if the value of the counter 34C is "0" (step S3; YES), then the vehicle is whether the pulse signal _{S P} whether or from CPU6 stopped If it is determined based on the GPS speed (step S5) and is not stopped (step S5; NO), the process proceeds to step S6. If it is stopped (step S5; YES), the process returns to the original main navigation program.

In the judgment in the step S5, when the vehicle is moving (step S5; NO), then, based on the GPS velocity data _{S G} from CPU 6, speed calculated by the positioning radio wave (hereinafter, referred to as GPS speed .) Is within a speed range that can be regarded as a predetermined constant speed (step S6). More specifically, four consecutive GPS speeds are held in a buffer (not shown) in the sub CPU 34, and a speed difference between any two of the four GPS speeds is obtained. It is determined whether or not the speed differences for the two combinations are all within a speed range that can be regarded as equal speed. Here, the speed range that can be regarded as a predetermined constant speed corresponds to the count value n (number of times the unit movement distance is calculated) in the counter 34C, and improves the accuracy of the unit movement distance each time the number is repeated. Therefore, it is set in advance as shown in the right column of FIG.

And when it is not in the speed range which can be regarded as constant speed (step S6; NO), it returns to the process of step S2 without updating a unit movement distance, and is in the speed range which can be regarded as constant speed. the (step S6; YES), then, per unit of the pulse signal S _P time (e.g., every 1 second) whether the number of pulses in the range number of pulses can be regarded as a predetermined constant speed of Determination is made (step S7). More specifically, as in the case of GPS speed, four consecutive pulses per unit time are held in a buffer (not shown) in the sub CPU 34, and among the four pulses per unit time, The difference between the number of pulses per unit time of any two is obtained, and whether or not the above differences for all two combinations are all within the range of the number of pulses that can be regarded as equal speed. Determined. Here, the range of the number of pulses that can be regarded as a predetermined constant speed corresponds to the count value n in the counter 34C, for example, the left column in FIG. It is preset as follows.

If it is not within the range of the number of pulses that can be regarded as equal speed (step S7; NO), the process returns to step S2 without updating the unit movement distance. On the other hand, when in the number of pulses in the range can be regarded as a constant speed (step S7; YES), a constant speed and the moving speed and the GPS speed is both in the self-contained positioning system is calculated based on the pulse signal S _P It will be that. This state corresponds to the constant velocity portion shown in FIG. 4 and is determined to be a state where there is no influence of the time lag of the calculation timing between the GPS speed calculation timing and the movement speed calculation timing in the autonomous positioning system. It is.

When the conditions shown in steps S6 and S7 are satisfied, sub CPU34, by dividing the GPS speed number of pulses per unit time (1 sec) of the pulse signal _{S P,} and calculates a unit moving distance (step S8) .

  Next, it is determined whether or not the value of the counter 34C is “1” (step S9). If it is “1” (step S9; YES), it is assumed that this is the very initial stage of vehicle movement, and will be described later. / A reverse logic automatic determination routine is executed (step S10), and then the process proceeds to step S11. The forward / reverse logical automatic determination routine in step S10 stores the logical level of the reverse signal at the time of forward movement so that the movement distance at the time of backward movement of the vehicle is not added to the movement distance that should be originally calculated at the time of forward movement. 3, the reverse signal is monitored during the movement distance calculation process shown in FIG. 3, and if the logical level is other than the logical level of the reverse signal at the time of forward movement in the movement distance calculation step (step S <b> 4), the reverse movement is in progress. Is a process for not adding the moving distance at that time. Further, when the count value n is “1”, the forward / reverse logical automatic determination routine is executed because the logical level in the backward signal is checked as early as possible when performing the movement distance calculation process. This is because it is necessary to grasp this. Details of the forward / reverse logic automatic determination routine will be described later.

  If the count value n is not “1” in the determination in step S9 (step S9; NO), it is next determined whether the count value n is “1” or “a” (step S11). . Here, the count value “a” is the value of the number of updates for which it is determined that the error in the unit movement distance is almost zero, that is, the unit movement for which it can be determined that the unit movement distance has sufficiently converged. The number of distances is updated, and a specific value of a is, for example, “150”.

  If the count value n is “1” or “a” in the determination in step S11 (step S11; YES), the latest unit movement distance is stored in the RAM 35 or 36 (step S12). Thereafter, the process proceeds to step S13. At this time, if it is preset that the vehicle on which the travel distance calculation process shown in FIG. 3 is executed is equipped with summer tires, the unit travel distance updated in step S4 is stored in the RAM 35, and winter. If it is preset that the tire is mounted, the updated unit movement distance is stored in the RAM 36. Further, when the count value n is “1”, the RAM 35 or the RAM 36 stores the unit movement distance calculated and stored first when the count value n is later (count value n of 2 or more). This is because the movement distance is calculated based on this, and the reason why it is stored in the RAM 35 or 36 when the count value n is “a” is to store it after the accuracy as the unit movement distance is sufficiently improved. .

  If the count value n is not “1” or “a” in the determination in step S11 (step S11; NO), it is next determined whether or not the count value n is “a” (step S13). If the count value n is “a” (step S13; YES), a noise filter automatic switching routine described later is executed (step S14), and then the process proceeds to step S15. The noise filter automatic switching routine in step S14 is a process of discriminating the number of pulses per revolution of the axle based on the latest unit travel distance and switching between the high pulse number LPF 30 and the low pulse number LPF 31. Also, the noise filter automatic switching routine is executed when the count value n is “a” in accordance with the difference in frequency band between the high pulse number LPF 30 and the low pulse number LPF 31. This is because the process of step S14 is performed when it can be determined that the accuracy of the unit moving distance has improved to a degree sufficient to determine the low pulse number LPF 31. Details of the noise filter automatic switching routine will be described later.

  If the count value n is not “a” in the determination in step S13 (step S13; NO), it is next determined whether or not the count value n is equal to or greater than “a” (step S15). If the count value n is equal to or greater than “a” (step S15; YES), the processing of steps S16 and S17 is performed as a unit movement distance error automatic determination routine. The unit movement distance error automatic determination routine in steps S16 and S17 is, for example, when the above-mentioned unit movement distance is updated when the chain is mounted or slipped, the chain is mounted or slipped. This is a process for preventing the change in the temporary unit movement distance due to the above process, which is directly reflected in the update of the unit movement distance, resulting in a decrease in the accuracy of the unit movement distance. Further, when the count value n is equal to or larger than “a”, it can be determined that the unit movement distance error automatic determination routine is executed so that the accuracy of the unit movement distance is improved enough to determine the error. This is because sometimes the error is determined.

  More specifically, as the unit movement distance error automatic determination routine, a unit movement distance corresponding to the current count value n and a unit movement distance corresponding to the previous count value n ((current count value n) −1) are calculated. An error is determined (step S16). Then, the magnitude of the error is determined (step S17), and when the error is large (more specifically, for example, when the error is not within 3%) (step S17; YES), the chain is attached or slipped. As a result, the unit movement distance is not updated and the process returns to step S2.

  On the other hand, when the error is not large (more specifically, for example, when the error is within 3%) (step S17; NO), the process proceeds to step S18 to update the value of the unit movement distance.

  If it is determined in step S15 that the count value n is not equal to or greater than “a” (step S15; NO), the unit movement distance stored in a buffer (not shown) in the sub CPU 34 is calculated in step S8. Then, the value of the counter 34C is incremented by “1” (step S19), and then calculated (steps S6 to S8). The accuracy of the unit moving distance is counted by the counter 34C. In order to improve with the increase of the distance, the condition for calculating the next unit movement distance (steps S6 to S8) is changed (step S20). More specifically, the speed range that can be regarded as the constant speed that is the constant speed condition (step S6) in the GPS speed is narrowed by a predetermined amount (for example, 0.1 km / h).

Furthermore, narrowing the number of pulses in the range can be regarded as constant velocity is a constant velocity condition (step S7) relates to a pulse signal S _P by a predetermined amount (e.g., reduce one pulse.) (Step S21).

Here, in FIG. 5 when showing the change in the case of gradually strictly uniform velocity conditions relating constant velocity condition and the pulse signal S _P in GPS velocity corresponding to the count value of the counter 34C by the processing in step S20 and S21 As shown. As shown in the above steps S20 and S21, the gradual tightening of both constant velocity conditions requires a long time to calculate when the unit movement distance is determined with high accuracy from the beginning. This is to prevent the distance data _{SD from} becoming unavailable.

  Then, after resetting the allowable ranges of the two constant velocity conditions (steps S20 and S21), the process returns to step S2.

  Next, detailed processing of the unit movement distance switching routine in step S2 will be described using the flowchart of FIG.

As shown in FIG. 6, in the unit movement distance switching routine, first, it is determined whether or not a unit movement distance switching request is made from the input device 10 (step S20). At this time, when the user replaces the summer tire with the winter tire or replaces the winter tire with the summer tire, the user inputs a unit movement distance switching request from the input device 10. Then, CPU 6 is the unit travel distance switching request is inputted, outputs a RAM switching signal _{S C} to the sub CPU 34. Thereafter, the unit travel distance change request by RAM switching signal _{S C} from the CPU6 is recognized to have been inputted (step S20; YES), the sub CPU34, the unit moving distance of a unit travel distance being currently updated the data S _O is output to the corresponding RAM35 or RAM36 is stored (step S21), and thereafter, the unit travel distance switching unit travel distance data indicating a unit travel distance corresponding to the tire or winter tire for the specified summer by request reads S _O from the corresponding RAM35 or RAM 36 (step S22), and returns to the process shown in FIG.

  On the other hand, when the unit movement distance switching request is not made in the process in step S20 (step S20; NO), the process returns to the process shown in FIG. 3 without switching the unit movement distance.

In the very early stages of unit travel distance data S _O of a unit moving distance in either RAM35 or RAM36 is not stored, it is calculated by mounting one of the summer tires or winter tires units The movement distance is stored in both the RAM 35 or the RAM 36. When a tire other than the tire corresponding to the stored unit moving distance is mounted, the unit moving distance updated at that time is stored in the RAM 35 or RAM 36 corresponding to the tire.

  Next, detailed processing of the forward / reverse logic automatic determination routine in step S10 will be described with reference to the flowchart of FIG.

  As shown in FIG. 7A, in the forward / reverse logic automatic determination routine, if the count value n is “1” (step S9; YES), then in the backward signal (back signal). The current logical level (“H” or “L”) is determined (step S40), stored in a RAM (not shown) in the sub CPU 34, and the process returns to the process shown in FIG. At this time, since the processing shown in FIG. 3 is normally performed during forward movement, the logical level of the backward signal stored in the forward / reverse logical automatic determination routine corresponds to the logical level of the backward signal during forward movement. Accordingly, in the movement distance calculation process (step S4) when the count value n is 2 or more, if the logical level of the backward signal is a logical level other than the logical level determined in step S40, the calculation is performed at that time. The traveled distance is not added to the total travel distance. In order to improve the accuracy in the determination of the logical level of the reverse signal in the forward / reverse logic automatic determination routine, the constant speed value (denoted by the symbol “X” in FIG. 4) in the determination of the constant speed condition in steps S6 and S7. .) Is a value (for example, 30 km / h) that cannot be taken when reversing.

  Next, detailed processing of the noise filter automatic switching routine in step S14 will be described with reference to the flowchart of FIG.

As shown in FIG. 7B, in the noise filter automatic switching routine, when the count value n is “a” (step S13; YES), next, the length of the latest unit movement distance is determined. (step S45), switching the switches 32 and 33 by the switch control signal _{S SW} from the sub CPU34 corresponding to the value, select a high number of pulses for LPF30 and the low number of pulses for LPF 31 (step S46), the pulse signal _{S P} is input to the selected high number of pulses for LPF30 or low number of pulses for LPF31 are, to be output from the _{S P} 'as a switch 33 that high-frequency noise is removed to the sub CPU 34. Specifically, for example, the low pulse number LPF 31 is selected when the unit travel distance is 30 cm or more (corresponding to the number of pulses in one rotation of the axle is about 5 pulses or less). As described above, in the movement distance calculation process of the embodiment shown in FIG. 3, in the unit movement distance switching routine (step S2), a plurality of unit movement distances corresponding to a plurality of movement states are separately stored and moved. Sometimes, the unit movement distance corresponding to the movement state at the time of the movement is selected, and the movement distance is derived based on the selected unit movement distance and the number of pulses, so that the movement distance adapted to the movement state can be calculated.

  In the unit movement distance error automatic determination routine (steps S16 and S17), the error between the unit movement distance corresponding to the current count value n and the unit movement distance corresponding to the previous count value n is a predetermined threshold (3%). ) The unit travel distance is updated only in the following cases, and after that, the travel distance is derived based on the updated unit travel distance and the number of pulses. When the error is large (corresponding to “YES” in the process of step S17), the unit movement distance is not updated, and the influence of the large error on the unit movement distance can be removed. The influence on the derivation of the movement distance can be eliminated.

  Further, in the forward / reverse logic automatic determination routine (step S10), the logical level of the reverse signal when the vehicle is moving forward at 30 km / h or more is detected in advance, and the logic of the reverse signal is calculated in the actual movement distance calculation. Since the travel distance is calculated without counting the travel distance when the level is different from the forward logic level, the travel distance during the reverse travel is not counted as the travel distance of the vehicle traveling forward. The travel distance of the vehicle can be derived.

Furthermore, in the noise filter automatic switching routine (step S14), and to remove the high frequency noise of the pulse signal S _P to select the high number of pulses for LPF30 or low number of pulses for LPF31 corresponding to each unit travel distance, the high-frequency noise since but derives the movement distance of the vehicle based on the pulse signal S _P and the unit moving distance is removed, it is possible to derive the distance traveled by effectively remove the influence of high frequency noise has on the pulse signal S _P . In the above embodiment, although the LPF 2 types only, not limited to this, the frequency band of the pulse signal S _P which transmits the provided three or more multiple LPF different for each, based on the unit travel distance You may make it switch more finely.
(III) Application Example Next, an application operation of the vehicle navigation apparatus S using the movement distance calculated by the processes shown in FIGS. 3 to 7 will be described.
(A) Trip meter function First, the trip meter function in the vehicle navigation apparatus S using the calculated travel distance will be described with reference to FIG. Here, the trip meter function refers to a function for calculating the total travel distance of one day.

  In the trip meter function in the vehicle navigation device S, as a general rule, the ignition switch is turned on since the ignition switch (more specifically, the ACC (Accessory) switch) is turned on during the day in the timekeeping function of the CPU 6. The distance traveled until the vehicle is turned off is calculated by the processes shown in FIGS. 3 to 7, and the total travel distance of the day is calculated by repeating this and integrating the calculated travel distances throughout the day. To do.

Here, a trip meter function corresponding to various movement states of the own vehicle will be described.
(I) When the ignition switch is turned on when the date is changed (I) (corresponding to FIG. 8A)
In this case, while the ignition switch is turned on, it is considered as one day, and the travel distance is calculated, and the total travel distance when the ignition switch was turned on last time is calculated from the total travel distance up to now. Subtract and display as the total mileage of the day.

That is, in the case shown in FIG.
Today's total travel distance = (current total travel distance B)-(total travel distance A when the ACC switch is on)
It becomes.
(Ii) When the ignition switch is turned on when the date is changed (II) (corresponding to FIG. 8B)
In this case, the travel distance is accumulated on the same day as the day when the ignition switch is turned off and the day when it is turned on again, and the total distance when the ignition switch was turned on the previous time is calculated from the total distance traveled so far. The total travel distance of the day is displayed by subtracting the travel distance.

That is, in the case shown in FIG.
Today's total travel distance = (current total travel distance B)-(total travel distance A when the ACC switch is on)
It becomes.
(Iii) When the ignition switch is turned off at the time of date change (corresponding to FIG. 8 (c), this is the case of the above principle)
In this case, when the ignition switch is turned off, the total travel distance is once completed, and the total travel distance of the day is calculated. Then, the accumulation of the travel distance of the next day is started from the time when the date changes and the ignition switch is turned on next time.

That is, in the case shown in FIG. 8C, the total mileage on the second day is
Today's total travel distance = (current total travel distance B)-(total travel distance A 'when the ACC switch is on)
It becomes.
(B) Fuel consumption display function Next, the fuel consumption display function in the vehicle navigation apparatus S using the travel distance will be described. Here, the fuel consumption display function refers to a function of displaying a value divided by the total fuel amount (input via the input device 10) using the travel distance.

  In the fuel consumption display function in the vehicle navigation device S, in principle, the total fuel consumption is calculated by dividing the total travel distance up to the present by the total fuel. Here, regarding the fuel consumption for each refueling every time fuel is supplied, when the latest fuel amount is input, the fuel consumption for each refueling is divided by the amount of fuel supplied by the travel distance from the previous refueling. Is calculated and displayed. As the fuel amount supplied at this time, the latest value is used among the fuel amounts stored every time fuel is supplied.

  As another example, when the fuel amount input at the time of refueling in the past is corrected, the fuel consumption for each refueling is the amount of fuel that has been refueled by the moving distance from the previous refueling, as described above. In this case, the travel distance from the previous refueling is calculated using the travel distance calculated up to the previous refueling and stored in the RAM 8, and the amount of fuel supplied is Use the corrected amount of fuel.

  As described above, if the trip meter function and the fuel consumption display function are executed using the travel distance calculated by the processes shown in FIGS. 3 to 7, the total travel distance or fuel consumption of the day can be calculated more accurately. it can.

  Furthermore, in addition to the above-described application examples, for example, the moving distance distance for 30 minutes can be calculated by the processing shown in FIGS. 3 to 7, and the average speed can be obtained by dividing the distance by time (30 minutes). . In this way, various conveniences in vehicle operation can be achieved by using the travel distance calculated by the processes shown in FIGS.

  Furthermore, although the case where the vehicle navigation device S is applied to an automobile has been described in the above-described embodiment, it can also be applied to a vehicle such as a motorcycle or a tricycle.

It is a block diagram which shows the schematic structure of the navigation apparatus in embodiment. It is a block diagram which shows the detailed structure of the mileage sensor in embodiment. It is a flowchart which shows the movement distance calculation process in embodiment. It is a figure explaining the uniform velocity conditions in an embodiment. It is a figure which shows the relationship between the tolerance | permissible_range and count value in constant velocity conditions. It is a flowchart which shows the detailed process of a unit movement distance switching routine. 5 is a flowchart showing detailed processing of a forward / reverse logic automatic discrimination changing routine and a noise filter automatic switching routine; (a) is a flowchart showing a forward / reverse logic automatic discrimination changing routine; and (b) is a noise filter automatic switching routine. It is a flowchart which shows detailed processing of. It is a figure explaining the trip meter function of an application example, (a) is a figure which shows example (i), (b) is a figure which shows example (ii), (c) The figure which shows example (iii) It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Angular velocity sensor 2 ... Travel distance sensor 3 ... GPS receiver 4 ... System controller 5 ... Interface 6 ... CPU
7 ... ROM
8, 35, 36 ... RAM
DESCRIPTION OF SYMBOLS 9 ... Bus line 10 ... Input device 11 ... CD-ROM drive 12 ... Display unit 13 ... Graphic controller 14 ... Buffer memory 15 ... Display control part 16 ... Display 17 ... Sound reproduction unit 18 ... D / A converter 19 ... Amplifier 20 ... Speaker 30 ... LPF for high pulse number
31 ... Low pulse number LPF
32, 33 ... switch 34 ... sub CPU
34A ... Counter S ... vehicle navigation apparatus S D _... distance data S _G ... GPS velocity data S _C ... RAM switching signal S _{SW ...} switching signal _{S P,} S _P '... pulse signal S O _... unit travel distance data

Claims (2)

A measuring means for measuring the moving speed of the moving body;
Determination means for determining whether the measured moving speed is equal to or higher than a preset setting speed;
Detecting means for detecting a logic level of a signal for turning on the backup lamp of the moving body at every predetermined timing ;
Storage means for storing the logical level detected by the detection means when the moving speed is equal to or higher than a set speed, as a logical level when the moving body moves forward ;
Calculating means for calculating a moving distance when the moving body moves forward;
With
As the calculating means, wherein said logic level detected by the detection means, when a logic level different from the level at the time of the forward stored in the storage means, the moving body is retracted, the moving distance deriving device, characterized in that not be included a moving distance at the time of retreat the moving distance at the time of the forward. A measurement process for measuring the moving speed of the moving object;
A determination step of determining whether the measured moving speed is equal to or higher than a preset setting speed;
A detection step of detecting a logic level of a signal for turning on the backup lamp of the moving body at a predetermined timing ;
Storing the logic level detected when the moving speed is equal to or higher than a set speed as a logic level when the moving body moves forward ;
A calculating step of calculating a moving distance when the moving body moves forward;
Including
In the calculation step, when the detected logical level is different from the stored logical level at the time of forward movement, the moving distance at the time of backward movement is determined as the moving body is moving backward. moving distance deriving method characterized by not be included in the moving distance during the advance.

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