JP6421728B2 - OBE and GPS reception date / time generation program - Google Patents

Description

  The present invention relates to a vehicle-mounted device that generates a GPS reception date and time and a GPS reception date and time generation program based on a navigation message from a GPS satellite.

  Currently, it is planned to provide various services (ETC2.0 service) using a communication function called ETC2.0. As one of the ETC 2.0 services, the probe information collected by the vehicle is uplinked from the ETC 2.0 compatible vehicle-mounted device to the roadside device installed on the road, and the probe information collected from the whole country by the server is used as big data There is service.

Japanese Patent No. 4760532

By the way, the uplink probe information includes a travel history of the vehicle on which the vehicle-mounted device is mounted and date / time information at that time.
The date / time information is created based on navigation messages received from GPS satellites in ETC 2.0-equipped in-vehicle devices with GPS (Global Positioning System) function, but rollover occurs in date / time information using the GPS system. There is a problem of doing.

When rollover occurs, there is a problem that date information in the vehicle-mounted device malfunctions and uplinks incorrect probe information.
For such a problem, Patent Document 1 proposes to use date and time information of a map database (map information).

  However, since the technique of Patent Document 1 is a technique that uses date and time information of map information, it cannot be implemented with an on-board device that is compatible with ETC 2.0 and does not have map information (navigation function).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to mount correct date / time information in response to rollover when generating date / time information based on a navigation message from a GPS satellite. And providing a GPS reception date and time generation program.

  According to the invention of claim 1, the initial date / time setting means sets the latest date / time among the previous GPS reception date / time and the setup date / time backed up by the backup means during the previous operation as the initial date / time. Performs rollover determination with the initial date and time and the GPS navigation message, and if the rollover has occurred, the GPS reception date and time generation means expects a period corresponding to the rollover and calculates the GPS based on the navigation message. Since the reception date / time is generated, the current GPS reception date / time can be correctly generated.

The block diagram which shows the whole structure in one Embodiment Diagram showing the relationship between rollover and weeks Flow chart showing operation of control unit

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The date and time described in this embodiment is Greenwich Mean Time.
The ETC vehicle-mounted device 1 shown in FIG. 1 is mounted on a vehicle (not shown), receives a GPS signal transmitted from a GPS satellite that travels in the sky, and generates a GPS reception date and time indicating the current date and time based on the GPS signal. Thus, a predetermined ETC service is provided. The ETC vehicle-mounted device 1 includes a GPS receiving unit 2 that receives GPS signals transmitted from GPS satellites, and a control unit 3 that controls each unit of the ETC vehicle-mounted device 1 (setup date and time specifying means, initial date and time setting means, conversion means, rollover Determination means, GPS reception date and time generation means, backup means, and change means), a non-volatile memory 4, and setup information DB 5 (corresponding to storage means).

The control unit 3 includes a known microcomputer including a CPU 3a, a ROM 3b, and a RAM 3c.
The setup information DB 5 stores setup information necessary for setting up the ETC on-vehicle device 1 in the vehicle. The setup information includes setup date and time, license plate information (vehicle registration number and vehicle number described on the vehicle inspection certificate), vehicle verification (vehicle inspection certificate) information (vehicle size, weight, etc.), and the like.

  The setup information DB 5 also stores an effective range of setup date and time. The effective range of the setup date / time is for dealing with the case where the setup date / time is set by mistake. For example, from midnight on January 4, 2015 (Sunday) to March 17, 2035 (Saturday) ) 23:59:59. In other words, until 23:59:59 on Saturday, March 17, 2035, the GPS reception date and time can be correctly generated based on the navigation message from the GPS satellite without rollover as described later. However, after midnight on March 18, 2035 (Sunday), it is affected by a rollover that occurs at midnight on March 18, 2035 (Sunday).

  The effective range of the setup date and time can be arbitrarily set from an external device (not shown). When the ETC on-board device 1 is manufactured after midnight on March 18, 2035 (Sunday), or manufactured at the present time. If the ETC on-board device 1 is after midnight on March 18, 2035 (Sunday), it is a highly versatile configuration by storing the effective date and time until the next rollover occurrence date and time. Yes.

  The nonvolatile memory 4 stores the GPS reception date and time (hereinafter, the previous GPS reception date and time) backed up during the previous operation. When the nonvolatile memory 4 is manufactured, a predetermined fixed date is stored as an initial value of the previous GPS reception date. As this fixed date and time, it is a representative date and time that is unified for all products, not the date of manufacture. For example, by setting a simple date and time such as January 1, 2015, the error risk at the time of writing is reduced. The accuracy of the written value confirmation inspection is improved.

  Now, the GPS system is operating in a time system where the starting time (standard date and time) is midnight on January 6, 1980 in Greenwich Mean Time, and is the same as Coordinated Universal Time (UTC) The length of 1 second is inscribed. In other words, the elapsed seconds in the GPS system measured from the same timing and the elapsed seconds in UTC are completely the same.

  The navigation message transmitted by the GPS satellite includes a GPS navigation message indicating the elapsed time from the reference date and time on the GPS system. The GPS navigation message is a week number indicating the week number of the week measured from the standard date and time, and the lapse from Sunday 00:00 to Saturday 23:59:59 on the week indicated by the week number It consists of a week number that represents the number of seconds. Among these, the week number is expressed by 10-bit data, and can express from the 0th week to the 1023rd week (1024 weeks (≈19.6 years)).

  Therefore, according to the GPS navigation message, from midnight on Sunday, January 6, 1980, which is the start date and time of the 0th week, to August 21, 1999 (Saturday), which is the end date and time of the 1023 week. ) Until 11:59:59 p.m., but cannot represent the date after midnight on August 22, 1999 (Sunday).

  Then, at midnight on August 22, 1999 (Sunday), the week number is reset and counted again from the 0th week. This is a rollover of the GPS system. When a rollover occurs, the GPS reception date and time goes back 1024 weeks from the actual number of weeks, so a countermeasure is required. That is, the upper limit date and time of the GPS reception date and time generated based on the GPS navigation message is about 19.6 years from the reference date and time, and after that, measures against rollover are required.

At the present time (2015), since the first rollover has occurred, the number of weeks by the GPS navigation message is 1024 weeks back from the actual number of weeks.
On the other hand, the time system of the GPS system is the same highly accurate time system as the time system of UTC as described above, and the GPS navigation message is data representing an accurate date and time except for the Western calendar part.

  For this reason, a company that manufactures equipment that provides various services using the GPS reception date and time sets a new reference date and time (hereinafter referred to as a new reference date and time) offset from the reference date and time on the GPS system, By finding the elapsed time from the new reference date and time, the occurrence of rollover is delayed.

  That is, if, for example, midnight on August 2, 2015 (Sunday) is set as the new reference date and time, the week number indicated by the week number of the GPS navigation message is 832. Therefore, the number of weeks by the GPS navigation message = 832 is associated with the number of weeks converted to the new reference date and time (hereinafter referred to as converted week number) = 0. Similarly, considering whether or not a rollover has occurred in the number of weeks due to the GPS navigation message by associating the number of weeks according to the GPS navigation message = 833 to 1023, 0 to 831 with the converted number of weeks = 1 to 1023 Current date and time can be specified. In other words, at the present time, there is a one-to-one relationship between the number of weeks in the GPS navigation message and the number of conversion weeks, so it is possible to specify the number of weeks from the new reference date based on the number of weeks in the GPS navigation message. It becomes.

  Specifically, as shown in FIG. 2, at present, the current rollover on the GPS system (August 2, 1999 at midnight) and the second rollover (April 7, 2019 at midnight) Therefore, the week number W represented by the week number is a value W2 that goes back 1024 weeks from the true week number W1, and the week number corresponding to the W2 is the converted week number.

  However, when 1024 weeks have passed since midnight on Sunday, August 2, 2015 and midnight on Sunday, March 18, 2035, the number of weeks by the GPS navigation message returns to 832. The conversion week number is reset to zero. For this reason, rollover occurs on the conversion week number, and it becomes impossible to associate the week number on the GPS with the conversion week number. In other words, by adopting the new standard date and time, it is possible to delay the occurrence of rollover on the conversion week number, but when rollover occurs on the conversion week number, The number of conversion weeks will not be uniquely supported.

Therefore, in this embodiment, the conversion weekly report based on the new reference date and time is prevented from being affected by the occurrence of rollover as follows.
When the operator sets the ETC on-vehicle device 1 in the vehicle, first, the setup information including the setup date and time is stored in the setup information DB 5 in the ETC on-vehicle device 1.

  When the operator turns on the ACC switch of the vehicle in order to confirm the operation after setting up the ETC on-vehicle device 1 in the vehicle, power is supplied from the vehicle battery to the ETC on-vehicle device 1, so that the control unit 3 starts to operate.

When the operation starts, the control unit 3 executes the flowchart shown in FIG. This flowchart shows the operation of generating the GPS reception date / time among the operations of the ETC on-vehicle device 1.
The control unit 3 reads the initial value of the previous GPS reception date and time (in this embodiment, January 1, 2015) from the setup information DB 5 (S1) and reads the setup date and time (S2).

  Next, the effective range (in this embodiment, from midnight on January 4, 2015 (Sunday) to 23:59:59 on Saturday, March 17, 2035) is read from the setup information DB 5 and confirmed. (S3). If the operator correctly sets the setup date and time within the valid range, the setup date and time is valid (S3: Valid), so the previous GPS reception date and time are compared with the setup date and time (S4). At the time of setup of the ETC OBE 1, since 1:00 am of Sunday, January 1, 2015 is stored as the previous GPS reception date and time, the setup date and time is the latest (previous GPS reception date and time <setup Date) and setup date and time are set to the initial date and time (S5).

  Next, reception of the GPS navigation message is started (S7). When the GPS navigation message is received (S8: YES), rollover determination is performed based on the initial date and time and the GPS navigation message (S9). That is, when the conversion week number is reset when a rollover occurs, the conversion week number becomes a date and time earlier than the previous GPS reception date and time, so that it is possible to specify that the rollover has occurred on the conversion week number.

  Next, a GPS reception date is generated (S10). That is, when rollover does not occur in the conversion week number, the GPS reception date and time is generated based on the GPS navigation message as described above. On the other hand, when it is midnight on March 18, 2035 (Sunday) and it is specified that a rollover has occurred on the conversion week number, the current week number is calculated by adding 1024 weeks to the conversion week number. Identify. Further, by acquiring the elapsed seconds from the week number in the GPS navigation message, the elapsed seconds from midnight on Sunday in the conversion week number are specified. And the correct GPS reception date and time can be generated by adding the elapsed number of seconds on the GPS to the conversion week number from the new reference date and time.

Next, the GPS reception date and time generated as described above is stored in the nonvolatile memory 4 (S11).
When the controller 3 is powered and operated by turning on the ACC switch for the second time, when the previous GPS reception date and time are compared with the setup date and time (S4), the previous GPS reception date and time is the latest (previous time). GPS reception date / time ≧ setup date / time), the previous GPS reception date / time is set as the initial date / time (S6). In this case, since the previous GPS reception date and time is closer to the current date and time than the initial value of the previous GPS reception date and time, the rollover determination accuracy can be improved.

Then, it is determined whether or not a rollover has occurred as described above, and the GPS reception date and time generation processing can be executed by generating the GPS reception date and time based on the conversion week number and the elapsed second number.
Thereafter, the above-described operation is repeated every time the ACC switch is turned on.

  By the way, since the setup information is set by the operator's input operation, the set setup date and time may be incorrect. For example, if the date and time after the next rollover occurrence date / time in conversion week number (Sunday, March 18, 2035 midnight) is set incorrectly, rollover will occur in conversion week number. Although it is not, it is determined that a rollover has occurred. In such a case, since 1024 weeks are mistakenly added to the conversion week number, an incorrect GPS reception date and time is generated.

  Therefore, in this embodiment, the effective range is set as the setup date and time. As this effective range, the date and time until the rollover occurs on the conversion week number is set as described above. That is, as long as the setup date and time is within the valid range, rollover does not occur, and therefore, the GPS conversion date and time can be generated by specifying the correct conversion week number based on the week number by the GPS navigation message.

  If the second or later rollover occurs in the conversion week number, the configuration of this embodiment cannot generate an accurate GPS reception date and time, but the second rollover occurs in the conversion week number. This is after about 40 years from the present time, and the reliability of the product can be sufficiently ensured considering the product life.

According to such an embodiment, the following effects can be produced.
The ETC OBE 1 sets the latest date / time among the previous GPS reception date / time and the setup date / time backed up during the previous operation as the initial date / time, and then performs rollover determination using the initial date / time and GPS navigation message. When rollover has occurred, the GPS reception date and time is generated based on the navigation message in anticipation of the period corresponding to the rollover, so that the current GPS reception date and time can be correctly generated.

  This is a case where the previous GPS reception date / time is not stored for the first operation after setup because a predetermined fixed value until the rollover on the conversion week number is set as the initial value of the previous GPS reception date / time. However, the current GPS reception date and time can be correctly generated.

Set a valid range for the setup date and time, and if the setup date and time is outside the valid range, determine that the setup date and time is incorrect, and set the initial value of the previous GPS reception date and time as the initial date and time instead of the setup date and time. Therefore, even if the operator sets the setup date and time incorrectly, the rollover can be determined accurately.
Since the effective range of the setup date and time can be set from the outside, the versatility of the ETC on-vehicle device 1 can be improved.

(Other embodiments)
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.
The valid range of the setup date / time is not limited to immediately before the rollover occurrence date / time on the conversion week number, and any date / time can be set up to the rollover occurrence date / time.

The initial value of the GPS reception date / time is not limited to a fixed value unified to the product, and may be set for each product or lot as long as it is the date / time until the rollover on the conversion week number. It is good as date and time.
The present invention may be applied to a navigation device. In this case, the date / time information of the map data may be referred to.

  In the drawings, 1 is an ETC vehicle-mounted device (vehicle-mounted device), 3 is a control unit (setup date / time specifying means, initial date / time setting means, conversion means, rollover determination means, GPS reception date / time generation means, backup means, change means), 5 Is a setup information DB (storage means).

Claims (5)

Storage means (5) for storing setup information;
A setup date and time specifying means (3) for specifying a setup date and time included in the setup information;
An initial date and time setting means (3) for setting the latest date and time as the initial date and time among the previous GPS reception date and time set up during the previous operation and the setup date and time;
Conversion means (3) for converting the week number indicated by the week number of the navigation message received from the GPS satellite into a week number corresponding to the newly set reference date and time (hereinafter referred to as conversion week number);
Rollover determination means (3) for determining rollover by comparing the initial date and time and the conversion week number;
GPS reception date and time generation means (3) for generating a GPS reception date and time based on the rollover determination result and the conversion week number;
Backup means (3) for backing up the GPS reception date and time as the previous GPS reception date and time,
On-vehicle device equipped with.   The on-vehicle device according to claim 1, wherein the previous GPS reception date and time is set to a predetermined fixed value until a rollover on the conversion week number as an initial value.   The GPS reception date and time generating means confirms whether the setup date and time is within a predetermined effective range where the next rollover does not occur, and sets the GPS reception date and time as an initial date and time instead of the setup date and time if not within the effective range. The vehicle-mounted device according to 1 or 2.   Furthermore, the onboard equipment of Claim 3 provided with the change means which changes the said effective range according to the command from the outside. A procedure for storing setup information;
A procedure for specifying a setup date and time included in the setup information;
Among the previous GPS reception date and time and the setup date and time backed up during the previous operation, the latest date and time is set as the initial date and time,
A procedure for converting the number of weeks indicated by the week number of the navigation message received from the GPS satellite into the number of weeks corresponding to the newly set reference date (hereinafter referred to as conversion week number);
A procedure for determining a rollover by comparing the initial date and time and the conversion week number;
A procedure for generating a GPS reception date and time based on the rollover determination result and the conversion week number,
Backing up the GPS reception date and time as the previous GPS reception date and time,
GPS reception date and time generation program for executing

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