JP2013108761A - On-vehicle signal processing device and signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately determine a coefficient used for calculating a car speed or a traveling distance from a car speed pulse output from a car speed sensor even in a bad radio wave reception state of a vehicle.SOLUTION: The on-vehicle signal processing device includes an information processing unit 110 for calculating a car speed or a traveling distance based on a car speed pulse signal, a nonvolatile storage unit 120 for storing information about a speed pulse coefficient indicating characteristics of the pulse signal, an odometer numerical value input unit 113 for receiving the input of an odometer numerical value indicated by an odometer mounted on the vehicle, and a speed pulse coefficient correction unit 110 for calculating a first traveling distance indicating a difference between two odometer values input at two different points, calculating a second traveling distance based on the car speed pulse signal and the speed pulse coefficient input regarding movement between the two different points, and correcting the speed pulse coefficient based on the first traveling distance and the second traveling distance.

Description

  The present invention relates to an in-vehicle signal processing device and a signal processing method for calculating at least one of a vehicle speed and a travel distance based on a vehicle speed pulse signal output from a vehicle side.

  Conventionally, various in-vehicle devices that require vehicle information such as vehicle speed are mounted on passenger cars and various commercial vehicles. For example, for vehicles such as commercial trucks, digital tachographs that regularly acquire and automatically record information such as vehicle speed that represents the operating state, images taken by cameras in the event of accidents, vehicle speed, etc. A drive recorder that records information is installed. Also, an instrument panel unit that acquires information such as vehicle speed and displays it in real time is mounted on all vehicles.

  By the way, in a general vehicle, a vehicle speed sensor is installed in the vicinity of the output shaft of the transmission in order to obtain vehicle speed information. This vehicle speed sensor outputs one pulse signal each time the output shaft of the transmission rotates by a predetermined amount. Therefore, it is possible to grasp the current vehicle speed based on the pulse period of the pulse signal (that is, the vehicle speed pulse) output from the vehicle speed sensor and the number of pulses within a unit time, or it is possible to grasp the travel distance by counting the number of pulses. is there.

  Regarding the instructions of the speedometer for a four-wheeled vehicle, the JIS standard specifies that the driving rotational speed of the vehicle speed sensor is 637 rpm when the vehicle speed is 60 km / h. Further, it is defined that the number of pulses generated by the vehicle speed sensor per one rotation of the drive shaft is any one of 2, 4, 8, 16, 20, and 25.

  That is, the number of vehicle speed sensor generated pulses per rotation of the drive shaft may vary depending on the specifications of each vehicle. For example, a vehicle with a pulse number of 4 and a vehicle with a pulse number of 8 have significantly different periods of vehicle speed pulses even when traveling at the same speed. For example, when the tire size of the vehicle changes or the outer diameter of the tire changes due to wear due to long-term running, the relationship between the cycle of the vehicle speed pulse and the actual vehicle speed changes.

  Actually, when a manufacturer of a vehicle designs a corresponding vehicle type or changes specifications, the characteristics of the vehicle speed sensor mounted on the vehicle, that is, the number of pulses generated by the vehicle speed sensor per one rotation of the drive shaft are determined. Will be determined.

  On the other hand, for example, a general user or a company may purchase various vehicles such as a car navigation device, a drive recorder, and a digital tachograph after purchasing the vehicle. Since such an on-board device does not know in advance the specifications of the vehicle on which it is mounted, the characteristics of the vehicle speed pulse assumed by the on-vehicle device side and the vehicle speed pulse that is actually output from the vehicle side The characteristics may not match. As a result, the vehicle-mounted device calculates the speed or travel distance of the vehicle using an incorrect coefficient, resulting in a situation where the speed and travel distance cannot be recognized correctly. Therefore, it is necessary to match the characteristics of the vehicle speed pulse actually output from the vehicle side with the characteristics of the vehicle speed pulse assumed on the vehicle-mounted device side by some method.

  Patent Document 1 discloses a technique for automatically grasping the number of pulses per one rotation of a drive shaft with respect to vehicle speed pulses output by a vehicle speed sensor on the vehicle. In the vehicle operation management system disclosed in Patent Document 1, the current position of the vehicle is grasped using a GPS (Global Positioning System) receiver mounted on the vehicle, and speed information obtained by calculating the position and time is used. It is proposed to determine the number of pulses.

Japanese Patent Laid-Open No. 11-133046

  However, when using GPS as in Patent Document 1, it must be in a state where radio waves from a plurality of GPS satellites can always be received on the vehicle. However, in reality, when the vehicle travels between high-rise buildings in an urban area, travels through a tunnel, or travels through a forest lined with tall trees, radio waves from above the vehicle are blocked. Thus, the current position cannot be calculated by GPS temporarily.

  That is, in the technique of Patent Document 1, if the radio wave reception state on the vehicle is not good, whether the characteristics of the vehicle speed pulse actually output from the vehicle side match the assumed state. Cannot be calibrated and the coefficients used to calculate the vehicle speed and mileage cannot be calibrated.

  For example, when a new vehicle-mounted device is installed on the vehicle, when a vehicle tire is replaced, or when the outer diameter of the tire changes due to tire wear, the coefficient used to calculate the vehicle speed and mileage Need to be determined or calibrated. However, if the GPS radio wave cannot be received satisfactorily on the vehicle, the necessary information cannot be obtained, so the coefficient cannot be determined immediately even when the driver or the like desires.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to use a coefficient used when calculating a vehicle speed and a travel distance from a vehicle speed pulse output from a vehicle speed sensor, and a reception state of radio waves on the vehicle is poor. An object of the present invention is to provide an in-vehicle signal processing device and a signal processing method that can be determined immediately even in a situation.

In order to achieve the above-described object, the in-vehicle signal processing device according to the present invention is characterized by the following (1) to (3).
(1) a signal input terminal for inputting a vehicle speed pulse signal output from the vehicle side;
An information processing unit for calculating at least one of a vehicle speed and a travel distance based on a vehicle speed pulse signal input to the signal input terminal;
A non-volatile storage unit that holds information on a speed pulse coefficient representing a correspondence relationship between a vehicle speed or a travel distance and the characteristics of the vehicle speed pulse signal;
An odometer value input unit for receiving an input of an odometer value corresponding to a value displayed by an odometer mounted on the vehicle;
A first travel distance representing a difference between two odometer values input to the odometer value input unit at each of two different points is calculated, and the vehicle speed pulse signal input with respect to movement between the two points A speed pulse coefficient correction unit that calculates a second travel distance based on the speed pulse coefficient and corrects the speed pulse coefficient based on the first travel distance and the second travel distance;
(2) The on-vehicle signal processing device according to (1) above,
The odometer numerical value input unit accepts input of the odometer numerical value only in a state where the vehicle substantially stops traveling,
The speed pulse coefficient correction unit calculates the first travel distance and the second travel distance between two points in a state where the vehicle stops traveling.
(3) The on-vehicle signal processing device according to (1) above,
A position information input unit for inputting position information indicating the current position of the vehicle;
If the position information input unit is capable of acquiring the latest position information, the speed pulse coefficient correction unit is based on the speed calculated from the change in the position information and the input vehicle speed pulse signal. Modifying the velocity pulse coefficient.

According to the in-vehicle signal processing device having the configuration (1), the speed pulse coefficient is determined based on the odometer value when a driver or the like desires even in a situation where radio waves cannot be received on the vehicle. Can do. The odometer (cumulative odometer) is mounted on almost all vehicles such as automobiles, and is considered to always display the correct mileage, so the speed pulse coefficient is determined at any time regardless of changes in the vehicle status. it can.
According to the in-vehicle signal processing device having the configuration (2), since the odometer value is input only when the vehicle is stopped, it is possible to prevent the numerical value from changing between reading and input of the numerical value. Can be suppressed.
According to the in-vehicle signal processing device having the configuration (3), the speed pulse coefficient is corrected based on the change in the position information of the vehicle, so that the change in the tire diameter due to tire replacement or wear can be It is possible to calibrate the velocity pulse coefficient correctly.

In order to achieve the above-described object, the signal processing method according to the present invention is characterized by the following (4).
(4) A signal processing method for inputting a vehicle speed pulse signal output from the vehicle side and calculating at least one of a vehicle speed and a travel distance based on a pulse period or a pulse number of the vehicle speed pulse signal,
Holds speed pulse coefficient information indicating the correspondence between the vehicle speed or travel distance and the characteristics of the vehicle speed pulse signal,
Accepts input of odometer values corresponding to the values displayed by the odometer mounted on the vehicle,
Calculating a first mileage representing a difference between two odometer values inputted at two different points;
A second travel distance is calculated based on the vehicle speed pulse signal and the speed pulse coefficient input for the movement between the two points;
Correcting the speed pulse coefficient based on the first travel distance and the second travel distance;

  According to the signal processing method having the configuration (4), the speed pulse coefficient can be determined based on the odometer value when the driver or the like desires even in a situation where radio waves cannot be received on the vehicle. it can.

In order to achieve the above-described object, a signal processing program according to the present invention is characterized by the following (5).
(5) A signal processing executable by a predetermined computer for inputting a vehicle speed pulse signal output from the vehicle side and calculating at least one of the vehicle speed and the travel distance based on the pulse period or pulse number of the vehicle speed pulse signal A program,
Determining an initial value of information of a speed pulse coefficient representing a correspondence relationship between a vehicle speed or a travel distance and characteristics of the vehicle speed pulse signal;
Receiving an input of an odometer value corresponding to a value displayed by an odometer mounted on the vehicle;
Calculating a first mileage representing a difference between two odometer values input at two different points;
Calculating a second travel distance based on the vehicle speed pulse signal and the speed pulse coefficient input for the movement between the two points;
Correcting the speed pulse coefficient based on the first travel distance and the second travel distance.

  By executing the signal processing program having the configuration (5) above on a computer, the speed pulse coefficient can be calculated based on the odometer value when a driver or the like desires even in a situation where radio waves cannot be received on the vehicle. Can be determined.

  According to the in-vehicle signal processing device, the signal processing method, and the signal processing program of the present invention, the coefficient used when calculating the vehicle speed and the mileage from the vehicle speed pulse output from the vehicle speed sensor is a situation where the reception state of the radio wave on the vehicle is poor. Even so, it becomes possible to decide immediately. Since the odometer is mounted on most vehicles such as automobiles and is considered to always display the correct mileage, the speed pulse coefficient can be determined at any time regardless of changes in the vehicle status.

  The present invention has been briefly described above. Further, details of the present invention will be further clarified by reading through the modes for carrying out the invention described below with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a configuration example of an electric circuit of the in-vehicle signal processing device according to the embodiment. FIG. 2 is a flowchart showing coefficient determination processing of the in-vehicle signal processing device shown in FIG. FIG. 3 is a flowchart showing the speed Vgps acquisition process of the in-vehicle signal processing device shown in FIG. FIG. 4 is a schematic diagram showing the operation of the in-vehicle signal processing device shown in FIG.

  Specific embodiments relating to the in-vehicle signal processing device, the signal processing method, and the signal processing program of the present invention will be described below with reference to the drawings.

<Device configuration>
An example of the electric circuit configuration of the in-vehicle signal processing device 100 according to this embodiment is shown in FIG. The in-vehicle signal processing device 100 shown in FIG. 1 has a wireless communication function, and is configured to function as a telematics in-vehicle terminal that collects various information. In addition, data communication can be performed between the in-vehicle signal processing device 100 mounted on the vehicle and a server or the like installed outside the vehicle as necessary. Of course, the present invention is also assumed to be applied to various vehicle-mounted devices other than the telematics vehicle-mounted terminal, such as a drive recorder, a digital tachograph, a car navigation device, and the like.

  In the configuration example shown in FIG. 1, a control unit 110, a communication module 111, a GPS module 112, an external interface (I / F) 113, a display unit 114, a power supply unit 115, a speed interface 116, A rotation interface 117, a digital input interface 118, an external interface 119, and a nonvolatile memory 120 are provided.

  The control unit 110 is configured by a microcomputer. This microcomputer performs control for realizing functions required for the in-vehicle signal processing device 100 by executing a program incorporated in advance. The specific operation of the control unit 110 will be described later.

  The communication module 111 is connected to the communication antenna 11 mounted on the vehicle, and has a function for performing wireless communication using the communication antenna 11. Specifically, for example, it is possible to perform data communication with a radio base station of a communication facility that provides a mobile communication service, and communicate with a predetermined server via the radio base station. .

  The GPS module 112 is connected to the GPS antenna 12 mounted on the vehicle. The GPS module 112 can perform calculation based on radio waves from a plurality of GPS (Global Positioning System) satellites received by the GPS antenna 12 to grasp the current position of the vehicle.

  The external interface 113 is a communication interface for connecting various external devices to the in-vehicle signal processing device 100. In the example shown in FIG. 1, the operation unit 13 is connected to the external interface 113. The operation unit 13 includes buttons such as a numeric keypad that can accept an input operation from a driver or an operator.

  The display unit 114 is configured by a liquid crystal display panel or the like, and can display numerical values, characters, and the like as necessary. The display unit 114 is used to inform the driver or the operator of the operation state of the in-vehicle signal processing device 100.

  The power supply unit 115 is connected to a vehicle power supply 14 including a vehicle battery and the like. That is, when power is supplied from the vehicle power supply 14 in conjunction with the state of the engine key of the vehicle, the power supply unit 115 supplies predetermined power to each part of the in-vehicle signal processing device 100.

  The speed interface 116 is connected to a speed sensor 15 provided in the vehicle. The speed sensor 15 outputs a vehicle speed pulse every time the output shaft of the vehicle transmission rotates a predetermined amount. The speed interface 116 converts the vehicle speed pulse signal output from the speed sensor 15 into a signal suitable for the processing of the control unit 110.

  The rotation interface 117 is connected to an engine rotation sensor 16 provided in the vehicle. The engine rotation sensor 16 outputs a rotation pulse every time the output shaft of the vehicle engine rotates a predetermined amount. The rotation interface 117 converts the rotation pulse signal output from the engine rotation sensor 16 into a signal suitable for the processing of the control unit 110.

  The digital input interface 118 has five independent channel digital inputs. The digital input interface 118 is connected to the vehicle side device 17. The vehicle-side device 17 can output signals from various sensors mounted on the vehicle to the in-vehicle signal processing device 100.

  The external interface 119 is a communication interface for connecting various external devices to the in-vehicle signal processing device 100. As typical examples of the external device 18 connected to the external interface 119, a drive recorder, a digital tachograph, a car navigation device, and the like are assumed.

  The nonvolatile memory 120 can freely write and read data by accessing the control unit 110 from the microcomputer. The nonvolatile memory 120 can retain data even if it is cut off from the supply of power from the outside.

<Operation of the device>
<Explanation of speed pulse coefficient>
The control unit 110 shown in FIG. 1 has a built-in function for calculating the travel speed (vehicle speed) and travel distance of a vehicle on which the in-vehicle signal processing device 100 is mounted. That is, one pulse appears in the vehicle speed pulse signal output from the speed sensor 15 every time the vehicle travels a certain distance. Therefore, based on the pulse period of the vehicle speed pulse, or the number and time of pulses appearing within a certain time. Thus, the vehicle speed can be calculated. In addition, the travel distance can be calculated by counting the number of pulses that appear after a certain point in time.

  Actually, the vehicle speed and the travel distance are calculated based on the speed pulse coefficient Kp representing the number of pulses generated by the vehicle speed sensor per one rotation of the drive shaft of the vehicle and the pulse number or pulse period of the actually appearing pulse. However, the number of pulses per rotation of the drive shaft that is actually output by the speed sensor 15 varies depending on the vehicle type, specification, etc., and is a value of 2, 4, 8, 16, 20, or 25. Therefore, in the vehicle-mounted device such as the vehicle-mounted signal processing apparatus 100 mounted after the vehicle is manufactured, the speed pulse coefficient Kp assumed by the vehicle-mounted device side does not necessarily match the actual speed pulse coefficient. Further, when the tire outer diameter changes due to tire replacement or wear, the relationship between the actual number of pulses or pulse period and the amount of movement of the vehicle changes, and an error occurs in the calculated vehicle speed and travel distance.

  Therefore, the in-vehicle signal processing device 100 has a function for matching the speed pulse coefficient Kp assumed by the vehicle-mounted device side with the actual speed pulse coefficient and a function for suppressing the occurrence of calculation error due to a change in the tire diameter. Yes.

<Description of coefficient determination process>
The contents of the coefficient determination process in the in-vehicle signal processing device 100 shown in FIG. 1 are shown in FIG. The coefficient determination process shown in FIG. 2 is performed by the microcomputer of the control unit 110 when a predetermined condition is satisfied, for example, immediately after the apparatus is turned on, when a certain time elapses, or when a predetermined command is input. It is executed by. The coefficient determination process shown in FIG. 2 will be described below.

  In step S11, the control unit 110 refers to the data of the velocity pulse coefficient Kp allocated on the nonvolatile memory 120, and identifies whether or not this has been determined. That is, immediately after the in-vehicle signal processing device 100 is shipped from the factory and mounted on the vehicle, the value of the speed pulse coefficient Kp is not determined and an invalid value (for example, 0) is assigned. Whether the value has been determined is identified by checking whether the value of Kp is invalid. If not determined, the process proceeds to S12, and if determined, the process proceeds to S16.

  In step S12, the control unit 110 identifies whether or not the vehicle on which the in-vehicle signal processing device 100 is mounted is stopped. For example, if no pulse appears in the vehicle speed pulse signal input from the speed sensor 15 within a predetermined time, it is recognized that the vehicle is stopped and the process proceeds to the next S13.

  In step S <b> 13, the control unit 110 receives a coefficient input operation from an operator or a user (driver or the like) who installs the in-vehicle signal processing device 100. That is, by operating the operation unit 13, the speed pulse coefficient Kp on the nonvolatile memory 120 is updated to the initial value. As for the initial value, an assumed numerical value may be directly input using a numeric keypad or the like, or one of a plurality of candidates (for example, 2, 4, 8, 16, 20, 25) prepared in advance. May be selected.

  In step S <b> 14, the control unit 110 receives an input operation of the odometer value Vod <b> 1 by an operator or a user (driver or the like) who installs the in-vehicle signal processing device 100. Here, an operator visually reads a numerical value (travel distance from the initial manufacture of the vehicle to the present) of an odometer (cumulative odometer) arranged on the instrument panel of the vehicle, and uses this value as an odometer numerical value Vod1. Can be input from the operation unit 13. The input odometer value Vod1 is stored in the nonvolatile memory 120.

  In step S15, the control unit 110 starts counting the vehicle speed pulse number Np. That is, after that, all the pulses of the vehicle speed pulse signal input from the speed sensor 15 are counted, and the integrated value is stored in the nonvolatile memory 120 as Np. Also, the speed Vgps acquisition operation (the process shown in FIG. 3) is started here.

  In step S16, it is identified whether or not the latest vehicle speed Vgps calculated using GPS (Global Positioning System) can be acquired. Normally, the speed Vgps can be acquired. For example, when a vehicle travels in a valley of a high-rise building, in a deep forest, or in a tunnel, it cannot receive the speed Vgps because it cannot receive radio waves from GPS satellites. . If the speed Vgps can be acquired, the process proceeds to the next S17, and if not acquired, the process proceeds to S19.

In step S <b> 17, the control unit 110 calculates the latest vehicle speed Vp based on the state of the pulse of the vehicle speed pulse signal input from the speed sensor 15 and the speed pulse coefficient Kp on the nonvolatile memory 120. For example, it can be calculated by the following equation.
Vp = (N1 / Kp) K0 / N2 [m / sec]
N1: Number of pulses detected within a predetermined time N2 (seconds) Kp: coefficient, number of pulses per rotation of the drive shaft (initial value or value after correction)
K0: coefficient, vehicle travel distance per drive shaft revolution (constant [m])

In step S18, the control unit 110 calculates the latest speed pulse coefficient Kp1 based on the vehicle speed Vgps obtained by GPS and the vehicle speed Vp obtained from the vehicle speed pulse signal in step S17. For example, it can be calculated using the following equation.
Kp1 = Kp · Vp / Vgps

  In step S19, the control unit 110 identifies whether or not the vehicle on which the in-vehicle signal processing device 100 is mounted is stopped. For example, if no pulse appears in the vehicle speed pulse signal input from the speed sensor 15 within a predetermined time, it is recognized that the vehicle is stopped and the process proceeds to the next S21. If the vehicle is not stopped, the process returns to S16 and is repeated.

  In step S21, the control unit 110 compares the current value of the vehicle speed pulse number Np whose coefficient was started in S15 with a predetermined threshold value Nmin, and if the condition of (Np> Nmin) is satisfied, the process proceeds to the next S22. If not, return to S16 and repeat the process.

  In step S22, control unit 110 accepts an input operation of odometer value Vod2 by a user (driver or the like). Here, the user visually reads the value of the odometer arranged on the instrument panel of the vehicle (the latest travel distance from the initial manufacture of the vehicle to the present) and inputs this value from the operation unit 13 as the odometer value Vod2. can do.

In step S23, the control unit 110 calculates two types of distances Dod and Dp using the following equations.
Dod = Vod2-Vod1
Dp = (Np / Kp) K0
Dod: Distance [m] determined by vehicle odometer
Dp: distance [m] obtained from the pulse state of the vehicle speed pulse signal and the speed pulse coefficient Kp
Np: current count value of the number of vehicle speed pulses K0: coefficient, vehicle travel distance per drive shaft revolution (constant [m])

In step S24, the control unit 110 calculates the latest speed pulse coefficient Kp1 based on the two distances Dod and Dp obtained in S23. For example, it can be calculated using the following equation.
Kp1 = Kp · Dp / Dod

  In step S25, the controller 110 determines whether or not the speed pulse coefficient Kp1 obtained in S18 described above or the speed pulse coefficient Kp1 obtained in S24 is an appropriate value suitable for correcting the speed pulse coefficient Kp so far. Identify

  For example, when the difference between the speed pulse coefficients Kp and Kp1 is extremely small and can be regarded as being within the range of the calculation error, it is not necessary to correct the speed pulse coefficient Kp, so that the execution of the next S26 is omitted and the process is terminated. . When the difference between the speed pulse coefficients Kp and Kp1 is large to some extent and the value of the speed pulse coefficient Kp1 is close to any integer of “2, 4, 8, 16, 20, 25”, the speed pulse Kp is Since there is a high possibility that the initial value assigned in S13 remains, the speed pulse coefficient Kp1 is regarded as an appropriate value, and the process proceeds to the next S26.

  In step S26, the control unit 110 corrects the speed pulse coefficient Kp using the speed pulse coefficient Kp1 obtained in step S18 or S24 described above. That is, the speed pulse coefficient Kp on the nonvolatile memory 120 is updated to the same value as the speed pulse coefficient Kp1.

<Description of speed Vgps acquisition processing>
The contents of the speed Vgps acquisition process of the in-vehicle signal processing device shown in FIG. 1 are shown in FIG. In other words, the process of FIG. 3 is executed by the control unit 110 in order to obtain the speed Vgps referred to in step S16 of FIG. The processing of FIG. 3 will be described below.

  In step S31, the control unit 110 identifies whether or not the GPS antenna 12 connected to the GPS module 112 has received radio waves from a plurality of GPS satellites. If the radio wave is received, the process proceeds to the next S32. If the radio wave cannot be received, the process waits until it can be received.

  In step S32, the control unit 110 stores the current position P1 of the vehicle calculated in the previous process (S33) as the previous position P2.

  In step S33, the latest vehicle position is obtained by calculation based on the radio wave and time received by the GPS module 112 from a plurality of GPS satellites. This calculation result is stored as the latest current position P1.

In step S34, the control unit 110 calculates the difference (position change: distance) between the latest current position P1 acquired in S33 and the previous position P2, and the time change Δt from acquiring P2 to acquiring P1. Based on the above, the speed Vgps is calculated. That is, the following equation is calculated.
Vgps = (distance of P1−P2) / Δt

  In step S35, the control unit 110 identifies whether or not the reliable speed Vgps has been calculated in S34. For example, when the number of satellites that can simultaneously receive radio waves is small and the position calculation error is large, or the calculated speed Vgps is within a predetermined range suitable for coefficient correction (for example, a range of 30 to 100 km / h). Otherwise, it is considered that the calculation has failed, and the process proceeds to the next S36. If the calculation of the speed Vgps is successful, the process returns to S31 and is repeated.

  In step S36, the controller 110 stores an error occurrence so that it can be understood that the calculation of the speed Vgps has failed. Further, for obtaining the speed Vgps, speed information that can be obtained by calculation in a GPS satellite may be used.

<Description of operation of specific example>
A specific example of the operation of the in-vehicle signal processing device 100 will be described with reference to FIG. In FIG. 4, the time when the vehicle-mounted signal processing device 100 is attached to the vehicle and the operation is started is defined as time t1, and at time t2 after the vehicle has traveled for a while, the speed pulse coefficient cannot be received from the GPS satellite. The case where Kp is corrected is assumed.

  At time t1, when the vehicle is stopped, the process of the control unit 110 proceeds to S14 through steps S11, S12, and S13 of FIG. Here, a driver or an operator reads a numerical value (for example, 100 km) of an odometer on the instrument panel, and operates the operation unit 13 to input the numerical value to the in-vehicle signal processing device 100. The controller 110 stores the numerical value input in step S14 as an odometer numerical value Vod1. Further, the controller 110 starts counting the vehicle speed pulse number Np (S15).

  When a predetermined condition is satisfied after time t1, control unit 110 generates a speed pulse coefficient setting request. For example, in the processing shown in FIG. 2, this request is generated when the vehicle is stopped and the vehicle speed pulse number Np exceeds the threshold value Nmin.

  In FIG. 4, a speed pulse coefficient setting request is generated at time t2. Here, the driver or the operator recognizes the speed pulse coefficient setting request through LED display or message display on the display unit 114, and performs a predetermined input operation. That is, a driver or an operator reads a numerical value (for example, 200 km) of an odometer on the instrument panel, and operates the operation unit 13 to input the numerical value to the in-vehicle signal processing device 100.

  The control unit 110 receives the numerical value input here (S22) as an odometer numerical value Vod2. Then, two types of distances Dod and Dp are calculated (S23). The distance Dod is the difference between the two odometer values Vod2 and Vod1, and is calculated as 100 [km] in the example of FIG. The distance Dp is calculated based on the vehicle speed pulse number Np at the time t2 and the current speed pulse coefficient Kp, and is calculated as 200 [km] in the example of FIG.

At time t2, the control unit 110 calculates the latest speed pulse coefficient Kp1 necessary for correcting the speed pulse coefficient Kp by the following equation (S24).
Kp1 = Kp · Dp / Dod

  In the example shown in FIG. 4, it is assumed that the distance Dod is 100 km and the distance Dp is 200 km, and it is assumed that “4” is assigned as the initial value to the speed pulse coefficient Kp at time t1. The speed pulse coefficient Kp1 is “8”.

  Further, since the speed pulse coefficient Kp needs to be corrected by comparing the distances Dod and Dp and the speed pulse coefficient Kp1 is considered to be appropriate, the control unit 110 proceeds to the processing from step S25 to step S26 and updates the speed pulse coefficient Kp to the latest. The speed pulse coefficient Kp1 is updated (corrected). That is, in the example of FIG. 4, the speed pulse coefficient Kp is corrected from “4” to “8” by the coefficient correction at time t2.

  In the example shown in FIG. 4, it is assumed that the on-vehicle signal processing device 100 on the vehicle cannot correctly receive the radio wave from the GPS satellite at time t2, but when the radio wave from the GPS satellite can be received, Steps S17 and S18 of FIG. 2 are executed. In that case, the speed Vgps is calculated based on the position information automatically acquired by the GPS, and the speed pulse coefficient Kp1 is calculated by comparing the speeds Vgps and Vp.

<Advantages of in-vehicle signal processing device 100>
Even when the in-vehicle signal processing apparatus 100 cannot receive radio waves from GPS satellites on the vehicle and cannot determine the current position and speed Vgps of the vehicle, as in the case of time t2 shown in FIG. , Dp can be calculated and the velocity pulse coefficient Kp can be corrected at any time based on these. Therefore, even in a situation where the specification of the speed sensor 15 mounted on the vehicle is unknown, the speed pulse coefficient Kp used by the in-vehicle signal processing device 100 for calculating the vehicle speed and the travel distance matches the specification of the speed sensor 15. It can be corrected automatically.

  Further, in a situation where radio waves from GPS satellites can be received on the vehicle, the speed pulse coefficient Kp is corrected based on the speed Vgps calculated based on the current position of the vehicle and the vehicle speed Vp calculated based on the vehicle speed pulse. Can do. Thereby, the calculation error of the vehicle speed and the mileage caused by the difference in the tire diameter can be reduced.

<Possibility of deformation of in-vehicle signal processing device 100>
The on-vehicle signal processing device 100 shown in FIG. 1 is assumed to calculate the vehicle speed and travel distance inside itself, but the function of calculating the vehicle speed and travel distance is connected to the outside of the on-vehicle signal processing device 100. You may mount in the onboard equipment. In this case, if the in-vehicle signal processing device 100 transmits information on the speed pulse coefficient Kp to another on-vehicle device, the other on-vehicle device can calculate the correct vehicle speed and travel distance based on the correct speed pulse coefficient Kp.

  In FIG. 1, it is assumed that the characteristic function of the present invention is installed in the in-vehicle signal processing device 100 configured as a telematics in-vehicle terminal, but it may be installed in other in-vehicle devices. For example, in-vehicle devices such as drive recorders, digital tachographs, and car navigation devices need to grasp information on vehicle speed and mileage, so that a function for determining the speed pulse coefficient Kp and automatically correcting it can be installed. desired.

  It should be noted that the conditions for the in-vehicle signal processing device 100 to assign an initial value to the speed pulse coefficient Kp and the conditions for accepting each input operation of the odometer values Vod1 and Vod2 (S11, S12, S19, S21) are appropriately determined as necessary. It is possible to change. Further, the condition (S25) for the control unit 110 to correct the speed pulse coefficient Kp may be changed as needed.

  If possible, the in-vehicle signal processing device 100 can automatically acquire the information of the display value of the odometer on the instrument panel from the odometer, so that the input operation of the driver or the operator is unnecessary.

DESCRIPTION OF SYMBOLS 11 Communication antenna 12 GPS antenna 13 Operation part 14 Vehicle power supply 15 Speed sensor 16 Engine rotation sensor 17 Vehicle side apparatus 18 External apparatus 100 Car-mounted signal processing apparatus 110 Control part (information processing part, speed pulse coefficient correction part)
111 Communication module 112 GPS module (position information input unit)
113 External interface (odometer numeric input section)
114 Display Unit 115 Power Supply Unit 116 Speed Interface 117 Rotation Interface 118 Digital Input Interface 119 External Interface 120 Nonvolatile Memory (Nonvolatile Storage Unit)
Vod1, Vod2 Odometer value Kp, Kp1 Speed pulse coefficient Dod, Dp Travel distance Vp, Vgps Vehicle speed

Claims (4)

A signal input terminal for inputting a vehicle speed pulse signal output from the vehicle side;
An information processing unit for calculating at least one of a vehicle speed and a travel distance based on a vehicle speed pulse signal input to the signal input terminal;
A non-volatile storage unit that holds information on a speed pulse coefficient representing a correspondence relationship between a vehicle speed or a travel distance and the characteristics of the vehicle speed pulse signal;
An odometer value input unit for receiving an input of an odometer value corresponding to a value displayed by an odometer mounted on the vehicle;
A first travel distance representing a difference between two odometer values input to the odometer value input unit at each of two different points is calculated, and the vehicle speed pulse signal input with respect to movement between the two points A speed pulse coefficient correction unit that calculates a second travel distance based on the speed pulse coefficient and corrects the speed pulse coefficient based on the first travel distance and the second travel distance; An in-vehicle signal processing device. The in-vehicle signal processing device according to claim 1,
The odometer numerical value input unit accepts input of the odometer numerical value only in a state where the vehicle substantially stops traveling,
The speed pulse coefficient correction unit calculates the first travel distance and the second travel distance between two points in a state where the vehicle is stopped traveling. The in-vehicle signal processing device according to claim 1,
A position information input unit for inputting position information indicating the current position of the vehicle;
If the position information input unit is capable of acquiring the latest position information, the speed pulse coefficient correction unit is based on the speed calculated from the change in the position information and the input vehicle speed pulse signal. The in-vehicle signal processing device, wherein the speed pulse coefficient is corrected. A signal processing method for inputting a vehicle speed pulse signal output from a vehicle side and calculating at least one of a vehicle speed and a travel distance based on a pulse period or number of pulses of the vehicle speed pulse signal,
Holds speed pulse coefficient information indicating the correspondence between the vehicle speed or travel distance and the characteristics of the vehicle speed pulse signal,
Accepts input of odometer values corresponding to the values displayed by the odometer mounted on the vehicle,
Calculating a first mileage representing a difference between two odometer values inputted at two different points;
A second travel distance is calculated based on the vehicle speed pulse signal and the speed pulse coefficient input for the movement between the two points;
The signal processing method, wherein the speed pulse coefficient is corrected based on the first travel distance and the second travel distance.

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