GPS control unit

Abstract

The present invention aims to prevent errors from occurring in car navigation systems and the like by appropriately blocking GPS signals received from a GPS antenna before an error occurs, in order to prevent errors from occurring when the difference between vehicle driving information and vehicle positioning information based on GPS positioning information exceeds a predetermined threshold. [Solution] In order to solve the above problems, the GPS control device of the present invention is characterized by comprising: a vehicle driving information input means connected between a vehicle and a car navigation system, which inputs vehicle driving information output from the vehicle to the car navigation control device; a transit vehicle driving information input means that inputs transit vehicle driving information output to the car navigation system via the car navigation control device; a GPS signal input means; a calculation means; a storage means; and a GPS signal control output means that controls the GPS signal based on the comparison result by the calculation means and outputs it to the car navigation system.

Description

Technical Field

[0001] The present invention relates to a GPS control device that is added and connected to a device for controlling a car navigation device (hereinafter referred to as "car navigation") in order to enable viewing of video using a television, optical disk, memory, communication or network (hereinafter referred to as "television, etc.") while the vehicle is in motion, by controlling signals or data (hereinafter referred to as "vehicle driving information") using a vehicle stop signal indicating vehicle stop, a driving pulse signal indicating driving state, a parking signal, and a CAN or other vehicle data bus line (hereinafter referred to as "CAN, etc.") indicating various vehicle states. Hereinafter, for the purpose of enabling both viewing of television, etc. and navigation operation while the vehicle is in motion, an in-vehicle device connected between the vehicle and the car navigation is collectively referred to as a "car navigation control device".

Background Art

[0002] Normally, car navigation is set so that video such as a television cannot be viewed while the vehicle is in motion. This is to prevent the safety of driving from being reduced by the driver viewing video.

[0003] However, there are cases where passengers in the passenger seat or rear seat may wish to view video while the vehicle is in motion. In response to the case where a passenger wishes to view video, a device has been developed that is connected to a signal line for transmitting vehicle information from the vehicle to the car navigation and controls so that viewing of a television, etc. is possible even while the vehicle is in motion.

[0004] Patent Document 1 discloses an in-car television adapter for a car navigation system equipped with a television that works in conjunction with a driver assistance system, enabling television viewing even while the vehicle is in motion without interfering with the functions of the driver assistance system. In Patent Document 1, when the driver assistance system is not operating, the vehicle speed pulse signal (driving pulse signal) received by the television adapter is converted by the analog signal control unit of the television adapter into a signal indicating that the vehicle is stopped, even if it is actually moving, and then transmitted to the analog signal input unit of the car navigation system, thereby enabling television viewing even while the vehicle is in motion.

[0005] However, some car navigation systems installed in vehicles compare vehicle location information obtained from GPS positioning information and vehicle driving information, and if an inconsistency exceeding a predetermined threshold is detected in the vehicle location information, they determine it to be an error and stop the navigation settings and operation functions (hereinafter referred to as "navigation operation").

[0006] GPS is a global positioning system that utilizes positioning satellites. This specification includes Global Navigation Satellite System (GNSS). GPS positioning information is information obtained by positioning based on GPS radio signals (hereinafter referred to as "GPS signals") received from GPS antennas.

[0007] When using the in-car television adapter disclosed in Patent Document 1, vehicle driving information indicating that the vehicle is stationary is transmitted to the car navigation system via the in-car television adapter, even though the vehicle is actually moving. In this case, two different states, "stopped" and "driving," arise between the GPS positioning information, which reflects the actual state of movement, and the in-car television adapter.

[0008] If the vehicle's driving status, as determined from various vehicle information, is detected to be both "stopped" and "driving" for an extended period, some or all of the vehicle's driver assistance functions may shut down, or a warning may be displayed on the vehicle's display, potentially causing practical problems. Similar problems may occur not only when the detection of these different states is immediate, but also if the different states persist.

[0009] Patent Document 2 discloses prior art that, even if an error occurs in a car navigation system and an error message is displayed during TV mode, the system error information is rewritten and transmitted to the on-board electronic control unit (engine control unit) (hereinafter referred to as "on-board ECU") and on-board display device, thereby preventing the display of the error message and avoiding restrictions on the use of some vehicle functions. On the other hand, in navigation operation, the state in which the error occurred continues, resulting in a problem where the vehicle position stops in places where GPS positioning information cannot be obtained, such as tunnels, and voice guidance is not provided. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Patent No. 7130294 [Patent Document 2] Patent No. 7343949 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The present invention has been made in view of the above problems, and aims to prevent errors that may occur when outputting vehicle driving information to a car navigation system using a car navigation control device, in order to enable simultaneous viewing of television and other devices and operation of the navigation system while driving. Specifically, in order to prevent errors that occur when the difference between vehicle driving information input to the car navigation system via the car navigation control device (hereinafter referred to as "vehicle driving information via the car navigation control device") and vehicle position information obtained based on GPS positioning information exceeds a predetermined threshold, the present invention suppresses the occurrence of errors in the car navigation system and the in-vehicle ECU by appropriately blocking the GPS signal received from the GPS antenna connected to the vehicle and the car navigation system before an error occurs. [Means for solving the problem]

[0012] To solve the above problems, the GPS control device of the present invention is connected between a vehicle and a car navigation system, and operates while the vehicle is in motion. picture A GPS signal control device that is auxiliaryly attached to and connected to a car navigation control device that enables viewing of a vehicle, comprising: a vehicle driving information input means for inputting vehicle driving information output from the vehicle to the car navigation control device; a transit vehicle driving information input means for inputting transit vehicle driving information output to the car navigation via the car navigation control device; a GPS signal input means for inputting GPS signals from a GPS antenna; and a calculation means. The vehicle travel information and the route travel information are stored. The system comprises a storage means and a GPS signal control output means that controls the GPS signal based on the calculation result of the calculation means and outputs it to the car navigation system. The calculation means includes a comparison means for comparing the vehicle driving information and the route vehicle driving information, a determination means for determining whether the car navigation control device is operating in video viewing mode based on the result of the comparison, and an error avoidance means for avoiding the occurrence of an error in the car navigation system. The error avoidance means, when it is determined that the car navigation control device is operating in video viewing mode, monitors the elapsed time for error avoidance and avoids the recognition of an error in the car navigation system by blocking the GPS signal for a predetermined period or making it impossible to position before the elapsed time reaches a predetermined period. It is characterized by the following.

[0013] Furthermore, the GPS control device of the present invention is characterized by comprising error avoidance means that, under conditions in which the calculation means determines that an error has occurred in the car navigation system when the vehicle position information based on the vehicle travel information via the vehicle and the GPS positioning information based on the GPS signal differs continuously for a period of t3, or when the difference in vehicle position information exceeds a preset tolerance value and is detected for a predetermined time or a predetermined number of times or more, the calculation means monitors the elapsed time after the condition is met and avoids the recognition of an error in the car navigation system by blocking the GPS signal for a period of t4 or making positioning impossible before the elapsed time reaches the period of t3.

[0014] Furthermore, the GPS control device of the present invention has the calculation means, The system includes a determination means for determining whether the vehicle speed is above a predetermined speed based on the aforementioned vehicle driving information. The system is characterized in that, if the vehicle speed falls below a predetermined speed during the monitoring of the elapsed time, the monitoring is stopped, the elapsed time is reset, and the monitoring is not resumed until the vehicle speed returns to or above the predetermined speed.

[0015] Furthermore, the GPS control device of the present invention is characterized in that, when the GPS antenna of the vehicle fails to acquire GPS signals from positioning satellites and positioning becomes impossible, the calculation means stops monitoring the elapsed time, resets the elapsed time to its initial value, and does not resume monitoring the elapsed time until the GPS antenna receives GPS signals again and positioning becomes possible.

[0016] Furthermore, the GPS control device of the present invention is characterized in that the calculation means determines, based on the change in the vehicle driving information, whether or not an over-deceleration has occurred in which the vehicle speed suddenly decreases to a predetermined standard or higher.

[0017] Furthermore, the GPS control device of the present invention is characterized in that the calculation means repeatedly executes the error avoidance means while the vehicle travel information indicating that the vehicle is stopped despite being in motion is being continuously or intermittently transmitted by the car navigation control device.

[0018] In addition, the GPS control device of the present invention is characterized by including a GPS signal amplifier for preventing attenuation of GPS signals.

Advantages of the Invention

[0019] According to the GPS control device of the present invention, even when using a car navigation control device to enable viewing of a TV or the like during driving by the car navigation, in the car navigation, an error caused by a difference in vehicle position information obtained based on "vehicle travel information via a vehicle" and "GPS positioning information" obtained from the car navigation control device is avoided, and the effect of enabling continuous viewing of a TV or the like during driving can be achieved. Further, it is possible to suppress the unnecessary blocking of GPS signals or the occurrence of a positioning failure state in an attempt to avoid errors. Furthermore, it is possible to suppress an adverse effect on a driving support system or a failure detection device that is linked with the car navigation due to a difference in vehicle position information obtained by "vehicle travel information via a vehicle" and "GPS positioning information".

Brief Description of the Drawings

[0020] [Figure 1] It is an example of a system configuration diagram of a vehicle 20 when the GPS control device 10 according to the present invention is in use. [Figure 2] It is an example of a block diagram of related parts of the GPS control device 10 and the vehicle 20 according to the present invention. [Figure 3] It is an example of signal processing for confirming activation of the car navigation control device 32 in the GPS control device 10. [Figure 4] It is a diagram showing a case where an error occurs when the car navigation 30 uses GPS positioning information in combination and the vehicle position information obtained based on the vehicle travel information SG2 via a vehicle and the GPS positioning information is different. [Figure 5] It is a diagram showing an example of signal processing in the GPS control device 10 for avoiding an error caused by the accumulation of differences in vehicle position information obtained based on the vehicle travel information SG2 via a vehicle and GPS positioning information and supporting the coexistence of viewing a TV or the like and the navigation operation. [Figure 6] This diagram illustrates the signal processing that prevents errors when the car navigation system 30 does not perform a comparison of vehicle location information based on the route vehicle travel information SG2 and GPS positioning information at vehicle speeds below V1. [Figure 7] This diagram illustrates five examples of methods for controlling GPS signals to avoid errors. [Figure 8] This is an example of a flowchart of the main processing routine in the GPS control device 10 that avoids errors caused by the accumulation of discrepancies between vehicle location information based on transit vehicle travel information SG2 and GPS positioning information when using the car navigation control device 32. [Figure 9] This is an example flowchart of an interrupt processing routine in the GPS control device 10 that avoids errors caused by the accumulation of discrepancies between vehicle location information based on transit vehicle travel information SG2 and GPS positioning information when using the car navigation control device 32. [Figure 10] This is an example flowchart of the main routine when the GPS control device 10 monitors GPS positioning information when using the car navigation control device 32. [Figure 11] This is an interrupt processing routine that saves vehicle driving information SG1 output from vehicle 20, or transit vehicle driving information SG2 output from car navigation control device 32. [Figure 12] This interrupt processing routine determines whether the car navigation control device 32 is running, increments and saves the timer variable T3 each time a predetermined time has elapsed, and determines whether GPS positioning has been impossible for a predetermined period of time. [Figure 13] This is the interrupt handling routine for acquiring GPS positioning information. [Modes for carrying out the invention]

[0021] The embodiments for implementing the GPS control device 10 according to the present invention will be described with reference to the figures. Figure 1 is an example of a system configuration diagram of a vehicle 20 when using the GPS control device 10 according to the present invention. The vehicle 20 is equipped with a common bidirectional data bus line, such as CAN 50, to which sensors and control devices necessary for the safety and automation of the vehicle 20 are connected, and various signals are input and output. In Figure 1, the case in which sensors such as a front camera 60, a rear camera 62, an illuminance sensor 64, a front sonar 66, a back sonar 68, a vehicle speed sensor (not shown), and an acceleration sensor (not shown) are connected is shown.

[0022] In the above vehicle configuration, a car navigation control device 32 may be installed to enable simultaneous viewing of television and other devices and navigation operation while driving. The car navigation control device 32 is often an adapter-type device connected between the vehicle electronic control unit 22 and the car navigation system 30, and controls the car navigation system 30. In this invention, the on-board ECU 22 controls the vehicle driving information SG1, GPS signals, and the car navigation system 30. Normally, the car navigation system 30 is set so that it is not possible to view images such as television while the vehicle 20 is in motion. However, depending on the wishes of a passenger in the front passenger seat or rear seat, the car navigation control device 32 may be connected to the signal line that transmits the vehicle driving information SG1 from the on-board ECU 22 to the car navigation system 30, thereby controlling the car navigation system 30 and enabling viewing of television and other devices even while driving.

[0023] The GPS control device 10 is connected in parallel to the input signal line and output signal line of the car navigation control device 32, and determines the operating status of the car navigation control device 32 to perform GPS signal input / output control and GPS signal processing.

[0024] Vehicle 20 utilizes GPS for determining its position. A GPS antenna 40 (hereinafter, "GNSS antenna" and "GPS antenna" are collectively referred to as "GPS antenna") is usually connected to a car navigation system 30. Signals from various sensors are processed by the in-vehicle ECU 22 and transmitted (output) as vehicle information to safety devices, automation devices, and the car navigation system 30, and information feedback is received (input) from safety devices, automation devices, and the car navigation system 30 as needed.

[0025] Figure 2 is a block diagram of the GPS control device 10 and car navigation control device 32 according to the present invention, and a diagram showing the connection to the vehicle 20.

[0026] The GPS control device 10 includes a vehicle driving information input unit 15 as a vehicle driving information input means for inputting vehicle driving information SG1 output from the vehicle 20 to the car navigation control device 32, a transit vehicle driving information input unit 16 as a transit vehicle driving information input means for inputting transit vehicle driving information SG2 output to the car navigation 30 via the car navigation control device 32, a calculation unit 12 as a calculation means for performing calculations on the vehicle driving information SG1 and the transit vehicle driving information SG2, a storage unit 13 as a storage means for storing the vehicle driving information SG1, the transit vehicle driving information SG2 and other calculated values ​​according to the commands of the calculation unit 12, and a GPS signal input / output unit 14 that inputs a GPS signal from the GPS antenna 40 and outputs the GPS signal to the car navigation 30 after passing or blocking the GPS signal or processing the GPS signal according to the commands of the calculation unit 12. In addition to performing calculations on the vehicle driving information SG1 and the transit vehicle driving information SG2, the calculation unit 12 is equipped with a timer for time control and also controls the other units. The units are connected by a bus line 18 to facilitate the flow of information.

[0027] If the car navigation system 30 is unable to receive GPS signals and obtain GPS positioning information because the vehicle 20 enters a tunnel or for some other reason before an error occurs, it will be unable to compare the GPS positioning information with the vehicle location information based on the route travel information SG2, so the car navigation timer TC will be reset.

[0028] The GPS control device 10 can determine that the GPS signal is blocked when the vehicle 20 enters a tunnel, for example, by acquiring GPS positioning information, thus eliminating the need to block the GPS signal unnecessarily. The GPS positioning information may also be acquired from vehicle information transmitted via the acquisition CAN, etc. 50. Alternatively, GPS positioning information may be acquired by positioning the GPS signal obtained from the GPS antenna 40. Other well-known modifications are acceptable as long as they achieve the same effect.

[0029] The car navigation control device 32 is connected between the vehicle 20 and the car navigation system 30 and performs calculation processing to output vehicle travel information SG2 for the first period (hereinafter referred to as "period T1") and the second period (hereinafter referred to as "period T2") during period T2. During period T1, it indicates to the car navigation system 30 that the vehicle 20 is stopped (which is equivalent to outputting a vehicle stop status signal to the car navigation system 30), and during period T2, it outputs vehicle travel information SG2 for both periods T1 and T2 to the car navigation system 30, thereby enabling simultaneous viewing of television and navigation operation while driving. In this case, "period T1 and T2" refers to adjacent periods T1 and T2 or T2 and T1, as periods T1 and T2 occur repeatedly. This refers to vehicle driving information. The same applies hereafter. Figures 3(a) and (b) show the signal processing of the car navigation control device 32. Figure 3(a) shows the signal waveform transmitted from the vehicle 20 to the car navigation control device 32 while driving. Figure 3(b) shows the signal waveform transmitted from the car navigation control device 32 to the car navigation 30 during driving, from before watching TV, etc. until immediately after starting to watch TV, etc. To enable simultaneous viewing of TV, etc. and navigation operation while driving, the car navigation control device 32 employs signal processing that, although there may be some differences in the calculation processing method, indicates to the car navigation 30 that the vehicle 20 is stopped during period T1, and outputs the vehicle driving information SG2 for periods T1 and T2 to the car navigation 30 during period T2.

[0030] The GPS control device 10 may be incorporated inside the car navigation control device 32 and connected between the GPS antenna 40 and the car navigation system 30 on the GPS signal line. The GPS control device 10, by command from the calculation unit 12 to the GPS signal input / output unit 14, allows or blocks the GPS signal or causes the car navigation system 30 to enter a positioning loss state.

[0031] First, the basic operation of the GPS control device 10 according to the present invention will be described. The GPS control device 10 operates in conjunction with the car navigation control device 32. For this purpose, the GPS control device 10 needs to confirm that the car navigation control device 32 has been started. Figure 3(c) shows an example of signal processing in the GPS control device 10 to confirm that the car navigation control device 32 has been started. The GPS control device 10 may start controlling the GPS signal in synchronization with the timing when a passenger starts watching television, etc., and stop controlling the GPS signal in synchronization with the timing when watching television, etc., ends. Alternatively, the GPS control device 10 may start controlling the GPS signal when it detects that the operation switch of the car navigation control device 32 has been turned ON ("on") in order to watch television, etc., and stop controlling the GPS signal when it detects that the operation switch of the car navigation control device 32 has been turned OFF ("off").

[0032] The specific processing involves, after the start of watching television or the like, if the reference level of the vehicle driving information signal SG1 is H (high), sampling is started when it changes from H to L (low), or when it changes from L to H after changing from H to L. The vehicle driving information SG1 and the transit vehicle driving information SG2 are compared, and if the pulses show the same signal level for a predetermined number of consecutive times, it is determined that the car navigation control device 32 is not operating or that the operation of the car navigation control device 32 has ended. The following explanation assumes that the signal reference level of vehicle driving information SG1 is H. The reference level may also be L. Sampling may start at a predetermined time delay from the time when the level of vehicle driving information SG1 changes from H (high) to L (low), or when it changes from L to H after changing from H to L.

[0033] On the other hand, if a state in which the pulse signal levels are different is detected, the car navigation control device 32 is immediately determined to be operating. The predetermined number of times is, for example, 10 sampling times, and if the pulses continue to show the same level during that time, the car navigation control device 32 is determined to be not operating. The predetermined number of times is just an example. To elaborate further, during the T2 period when the car navigation control device 32 intermittently outputs transit vehicle driving information SG2 to the car navigation 30, the pulse levels of vehicle driving information SG1 and transit vehicle driving information SG2 may coincidentally match. Therefore, by confirming that the pulse levels of vehicle driving information SG1 and transit vehicle driving information SG2 continue to be the same level multiple times, it is possible to reliably determine that the car navigation control device 32 is not operating. Note that the specific predetermined number of times mentioned above will differ depending on the vehicle model, so it needs to be determined for each vehicle model. Alternatively, the pulse widths of vehicle driving information SG1 and transit vehicle driving information SG2 may be compared to determine whether the car navigation control device 32 is running or not. The car navigation control device 32 is operating when both television viewing and navigation operation are running simultaneously. The above example uses a vehicle speed pulse signal, but it is also possible to convert a digital signal obtained from CAN or similar sources into a pulse signal and apply it.

[0034] As described above, the GPS control device 10 can determine that the car navigation control device 32 is activated by comparing the vehicle driving information SG1 and the route vehicle driving information SG2. When the car navigation control device 32 is operating, there may be discrepancies between the vehicle position information obtained based on the route vehicle driving information SG2 and the GPS positioning information, which will cause an error in the car navigation system 30. However, the GPS control device 10, upon detecting the activation of the car navigation control device 32, performs corrective processing to avoid errors caused by discrepancies in vehicle position information.

[0035] First, Figure 4 shows a case where an error occurs when the car navigation control device 32 is used and the car navigation system 30 uses GPS positioning information in conjunction with the vehicle location information obtained based on the vehicle route information SG2 and the GPS positioning information, and these two values ​​differ. Figure 4(a) shows the signal waveform of the vehicle route information SG1 output from the vehicle 20 while it is in motion and input to the car navigation control device 32. Figure 4(b) shows the signal waveform of the vehicle route information SG2 transmitted to the car navigation system 30 by the car navigation control device 32, which enables simultaneous viewing of television and navigation operation while driving, while the vehicle is watching television. Figure 4(c) shows the timing at which the car navigation system 30 acquires the GPS signal. The figure is an example. The timing at which the GPS signal is acquired varies depending on the vehicle type, etc. Figure 4(d) is an image illustrating the processing of vehicle location information in the car navigation system 30.

[0036] The car navigation control device 32 outputs a vehicle stop status signal to the car navigation system 30 during period T1, and during period T2 outputs the vehicle travel information SG2 for both periods T1 and T2 to the car navigation system 30, repeating this process to enable simultaneous viewing of television and other devices and navigation operation while driving. When the car navigation control device 32 is started, the car navigation system 30 detects that the vehicle position information obtained based on the vehicle travel information SG2 and GPS positioning information is different. Upon detecting this difference, the car navigation system 30 resets the car navigation timer TC, and the car navigation timer TC starts counting a predetermined time (t3) (hereinafter referred to as "period t3"). Subsequently, GPS positioning information is periodically acquired and compared with the vehicle position information obtained based on the vehicle travel information SG2. If the discrepancy in vehicle position information occurs repeatedly, the car navigation system 30 determines that there is a discrepancy in the vehicle position. When the car navigation timer TC reaches the upper limit of period t3, if there is a discrepancy in the vehicle position, the car navigation system 30 determines that an error has occurred, and the car navigation system 30 and its driver assistance functions may stop.

[0037] If the car navigation system 30 is unable to receive a GPS signal, such as when the vehicle 20 enters a tunnel before an error occurs, and therefore cannot obtain GPS positioning information, it will be unable to compare the vehicle positioning information based on the GPS positioning information and the vehicle travel information SG2, so the car navigation timer TC will be reset. Next, when the car navigation system receives a GPS signal and detects that the vehicle positioning information obtained based on the vehicle travel information SG2 and the GPS positioning information is different, it will start counting the car navigation timer TC again.

[0038] Figure 5 shows an example of signal processing by the GPS control device 10, which controls the input and output of GPS signals in the car navigation control device 32 to enable both television viewing and navigation operation, while avoiding errors caused by discrepancies between vehicle position information obtained based on transit vehicle travel information SG2 and GPS positioning information.

[0039] Figure 5(a) shows the operation of the GPS control device 10 within the square frame. Using a timer variable T3 provided in the GPS control device 10, the GPS control device 10 cuts off the GPS signal before the car navigation timer TC reaches the upper limit of the t3 period, preventing the car navigation system 30 from recognizing an error, thereby preventing the car navigation system 30 from generating an error. The signal waveform in Figure 5(b) is the vehicle driving information SG1 that is normally output from the vehicle 20 to the car navigation system 30. In this embodiment, a vehicle speed pulse signal is used as an example. In this embodiment, the vehicle driving information SG1 is input to the car navigation control device 32 and the GPS control device 10. The signal waveform shown in Figure 5(c) shows the transit vehicle driving information SG2 that the car navigation control device 32 transmits to the car navigation system 10 for the purpose of enabling simultaneous viewing of television and other devices and navigation operation while driving. The transit vehicle driving information SG2 is also input to the GPS control device 10 and compared with the vehicle driving information SG1 to detect the activation of the car navigation control device 32 based on the state of the signal level and whether the pulse width matches or does not match. Figure 5(d) shows the timing of when the car navigation system 30 acquires the GPS signal. The figure is an example. Figure 5(e) visualizes the processing in the car navigation system 30, similar to Figure 4. When the GPS signal is interrupted or positioning is impossible, the car navigation system 30 does not perform error processing. Next, when the GPS signal becomes available and the vehicle position information obtained based on the route vehicle travel information SG2 and the GPS positioning information differs, the car navigation timer TC is reset and counting begins.

[0040] Before the car navigation timer TC reaches the upper limit of the t3 period, the GPS control device 10 cuts off the GPS signal for a predetermined period (t4) (hereinafter referred to as the "t4 period") to avoid an error in the car navigation system 30. After this, the GPS control device 10 resets the timer variable T3 again and controls the input and output of the GPS signal to periodically repeat the cut-off or positioning failure state. Through this control, the car navigation control device 32 continues to avoid errors occurring in the car navigation system 30 while it is operating.

[0041] Figure 6 shows the error avoidance process when the car navigation system 30 does not compare the vehicle position information based on the vehicle travel information SG2 and GPS positioning information when the vehicle speed is less than V1. The signal waveform in Figure 6(b) is the vehicle travel information SG1 that is normally output from the vehicle 20 to the car navigation system 30. The signal waveform shown in Figure 6(c) shows the vehicle travel information SG2 that the car navigation control device 32 transmits to the car navigation system 30 for the purpose of enabling simultaneous viewing of television and navigation operation while driving. Figure 6(d) shows the timing when the car navigation system 30 acquires the GPS signal. The figure is an example. Figure 6(e) shows the time chart of the signal processing of the car navigation system 30. When the car navigation system 30 detects that the vehicle position information obtained based on the vehicle travel information SG2 and GPS positioning information is different, it starts measuring with the car navigation timer TC and determines that an error has occurred when it is determined that the state of being different for the vehicle position information has accumulated for a continuous period of t3 and has exceeded a predetermined threshold. However, if the vehicle speed falls below V1 before reaching the upper limit of the t3 period, the car navigation system 30 stops comparing vehicle position information based on the route vehicle travel information SG2 and GPS positioning information, and resets the car navigation timer TC. Then, when the vehicle speed rises to V1 or higher again, and the system detects that the vehicle position information obtained based on the route vehicle travel information SG2 and GPS positioning information is different, it resumes measuring the car navigation timer TC and comparing vehicle position information based on the route vehicle travel information SG2 and GPS positioning information. Subsequently, if the discrepancy in the vehicle position information accumulates and continues to exceed a predetermined threshold, an error occurs in the car navigation system 30.

[0042] Another example of error detection by the car navigation system 30 is when a discrepancy in vehicle position information obtained based on transit vehicle information SG2 and GPS positioning information is detected for a predetermined period of time or longer within the t3 period. In this case as well, when the vehicle speed falls below V1, the comparison of vehicle position information obtained based on transit vehicle information SG2 and GPS positioning information is stopped, and the car navigation timer TC is reset. When the vehicle speed rises to V1 or higher again, and a discrepancy in vehicle position information obtained based on transit vehicle information SG2 and GPS positioning information is detected, measurement by the car navigation timer TC is resumed. Subsequently, when the car navigation timer TC reaches the upper limit of the t3 period, if a discrepancy in vehicle position information obtained based on transit vehicle information SG2 and GPS positioning information is detected for a predetermined period of time or longer, an error will occur in the car navigation system 30.

[0043] The area within the square frame in Figure 6(a) shows the operation of the GPS control device 10. When the GPS control device 10 detects that the car navigation control device 32 is operating, it monitors that the vehicle speed is V1 or higher, starts counting the timer variable T3 in the timer provided in the calculation unit 12, and confirms that T3 has not reached the upper limit of the t3 period. That is, it sets a threshold t3' (hereinafter referred to as "t3' time") when T3 is less than the upper limit of the t3 period, and determines whether T3 has reached t3' time or not. While making the above determination, if the vehicle speed falls below V1 during the t3 period, it resets the timer variable T3 and initializes the timer. After that, when the vehicle speed becomes V1 or higher, it starts counting T3, and when the timer variable T3 reaches t3' time, the GPS signal input / output unit 14 blocks the GPS signal for t4 period or puts it in a positioning-disabled state to prevent the car navigation system 30 from recognizing an error. Therefore, this system can be applied to avoiding errors when it is detected that different states have been accumulating for a continuous period of time t3 regarding the vehicle position information obtained based on the transit vehicle travel information SG2 and GPS positioning information, or when it is detected that the vehicle position information has been deviating by more than a predetermined tolerance value for a continuous period of time or longer within the period t3. The above example of an error is one caused by the transmission of a signal to the car navigation system 30 indicating that the vehicle 20 is stopped even though it is in motion, in order to watch television, etc., but it is also possible to avoid similar errors caused by other factors.

[0044] The following describes how the GPS signal is controlled in the GPS control device 10. A simple method involves inserting an electronic switch or mechanical switch contact in the GPS signal line from the GPS antenna 40 to the car navigation system 30, and selecting, by command from the calculation unit 12, to pass the GPS received signal SG3 as the GPS output signal SG4 or to block the GPS received signal SG3. However, various methods can be used, so several examples will be described.

[0045] Figure 7 shows five examples of methods for controlling GPS signals to avoid errors. Figure 7(a) shows a method in which a GPS input / output unit 14 is installed in the middle of the GPS signal line from the GPS antenna 40 to the car navigation system 30, and a semiconductor or a device capable of blocking (hereinafter referred to as "relay or other switch") is inserted into the GPS signal processing unit a141, and gain control is performed to block or attenuate the GPS signal with the semiconductor or relay or other switch, thereby making positioning using the GPS signal impossible. Gain control can also be performed to amplify the output of the semiconductor when the GPS signal is passing through. This method allows the system to select whether positioning using the GPS signal is possible or impossible based on a command from the calculation unit 12.

[0046] Figure 7(b) shows a method in which a GPS signal input / output unit 14 is installed in the middle of the GPS signal line from the GPS antenna 40 to the car navigation system 30, and the power supply to the GPS antenna 40 is controlled by the GPS signal processing unit b142. This method involves inserting a relay or other switch that can electrically energize or disconnect the circuit, such as a relay contact or semiconductor switch, into the power line supplied to the GPS signal line, and turning the relay or other switch OFF by a command from the calculation unit 12, thereby cutting off the power supply to the GPS antenna 40.

[0047] Figure 7(c) shows a method in which a dummy GPS antenna 440 is mounted in addition to the regular GPS antenna 40, and the GPS signal processing unit c143 provided in the GPS input / output unit 14 switches between the regular GPS antenna 40 and the dummy GPS antenna 440 to shift the GPS positioning information and control whether positioning is possible, impossible, or the positioning accuracy is reduced.

[0048] Figure 7(d) shows a method in which a GPS signal jamming antenna 442 is mounted near the regular GPS antenna 40, and the GPS signal processing unit d144 provided in the GPS input / output unit 14 controls the blocking or passing of GPS signals by turning the GPS signal jamming antenna 442 ON or OFF.

[0049] Figure 7(e) shows a method in which the GPS antenna 40 is housed in a shield case, the GPS antenna 40 is either retracted or opened, or a radio wave shielding plate facing upwards is placed at the GPS signal incidence position above the GPS antenna 40, and the GPS signal processing unit e145 provided in the GPS input / output unit 14 controls the shielding or passage of the GPS signal, thereby enabling or disabling positioning using GPS positioning information.

[0050] The above describes five examples, but the system is not limited to these and can be configured in combination. Any well-known method that allows for the selection of whether to pass or block GPS signals, and whether to enable or disable GPS positioning information, is acceptable.

[0051] Figures 8 and 9 are examples of flowcharts in the GPS control device 10 that avoid errors caused by the accumulation of discrepancies between vehicle position information obtained based on transit vehicle travel information SG2 and GPS positioning information. Figures 8 and 9 are examples of flowcharts in the GPS control device 10 when GPS positioning information is not monitored. The flowcharts are not limited to those described above, and other flowcharts that show similar effects may be used.

[0052] The flowchart according to the present invention starts the main process (hereinafter referred to as the "main routine") (M101), and immediately afterwards sets the GPS signal input from the GPS antenna 40 to pass to the car navigation system 30 (M102). This process is necessary because, when the GPS control device 10 is not operating, it is necessary to set the GPS signal to pass from the GPS antenna 40 to the car navigation system 30 as the initial setting. Subsequently, interrupts for vehicle information acquisition and sampling timer measurement are enabled (M103~M104). By enabling the vehicle information acquisition interrupt, the interrupt processing routines (I101~I115) that save the vehicle driving information SG1 output from the vehicle 20 and the transit vehicle driving information SG2 output from the car navigation control device 32, and confirm the occurrence of over-deceleration and the startup of the car navigation control device 32 become executable. In the explanation of Figures 8 and 9, the vehicle driving information SG1 is exemplified as a driving pulse signal, but the vehicle driving information SG1 may be vehicle speed data obtained from CAN, etc. 50 instead of a driving pulse signal. Here, the pulse period of the driving pulse signal represents the time it takes to travel a predetermined distance. Therefore, a shorter pulse width indicates a faster speed, and a longer pulse width indicates a slower speed.

[0053] Specifically, the vehicle information acquisition interrupt processing routine starts processing (I101) when it detects a driving pulse signal from the vehicle 20 or the car navigation control device 32. The driving pulse signal is detected when the signal potential changes from the reference level. The same applies hereafter. Note that the timing of the driving pulse signal detection is just an example; it may also be detected when the potential changes from the reference level and then returns to the reference level, or the driving pulse signal may be detected by acquiring both the potential change from the reference level and the subsequent potential change when returning to the reference level. Regardless of the flow or state of the main routine, the driving pulse signal is always acquired when it is output from the vehicle 20 or the car navigation control device 32. When a driving pulse signal is detected, the potential (H (high) or L (low) level) of the vehicle driving information SG1 and the potential (H (high) or L (low) level) of the transit vehicle driving information SG2 are saved (I102~I103). Next, the interval between the previously acquired pulse and the currently acquired pulse of the driving pulse signal is calculated to obtain the current vehicle speed (SpNow), and this is saved along with the previous vehicle speed (SpBf) (I104~I105). The method of obtaining the vehicle speed is not limited to this. By using the previous vehicle speed (SpBf) and the current vehicle speed (SpNow), it is determined whether or not deceleration exceeding a preset speed (hereinafter referred to as "over-deceleration") has occurred (I106). If over-deceleration has occurred, the over-deceleration flag is set (Vdwn=1) (I107), and if over-deceleration has not occurred, the over-deceleration flag is reset (Vdwn=0) (I108).

[0054] Next, it is determined whether the vehicle driving information SG1 and the route vehicle driving information SG2 are equal (I109). If they are equal, the car navigation control device startup confirmation counter (C1) is incremented (I110). If they are not equal, the counter (C1) is cleared (I111).

[0055] Whether the vehicle driving information SG1 and the transit vehicle driving information SG2 are equal can be determined by whether their respective signal levels show the same H (high) or the same L (low) at the same time, thereby determining whether the car navigation control device 32 is activated. Alternatively, it can also be determined by whether the pulse widths of the vehicle driving information SG1 and the transit vehicle driving information SG2 are the same during the same time period. Furthermore, the car navigation control device 32 can also be determined by detecting that the car navigation control device indicates to the car navigation 30 that the vehicle 20 is stopped during period T1 (which is equivalent to outputting a vehicle stop status signal to the car navigation 30), and that during period T2, it outputs the transit vehicle driving information SG2 for both periods T1 and T2 to the car navigation 30.

[0056] When the condition in which the vehicle driving information SG1 and the vehicle driving information via SG2 are equal exceeds a predetermined number of times (c1) (I112), the car navigation control device 32 is determined to be not running and the car navigation control device startup flag is reset (I113). If the vehicle driving information SG1 and the vehicle driving information via SG2 are not equal, the car navigation control device 32 is immediately determined to be running and the car navigation control device startup flag is set (I114).

[0057] This completes the interrupt processing and returns to the main routine step that was being processed immediately before executing the interrupt processing routine (I115). Excessive deceleration can occur during sudden stops or before curves. In the case of sudden stops without steering, GPS position correction is rarely involved, but if sudden deceleration occurs before steering, such as before a curve, a discrepancy may occur between the actual driving position and the signal output from the car navigation control device 32 during the T2 period when vehicle driving information SG1 for periods T1 and T2 is transmitted. When the car navigation system 30 receives direction change information from the acceleration sensor when the aforementioned discrepancy occurs, the display position on the car navigation screen is changed according to the accuracy of the GPS positioning information, resulting in the display showing the vehicle driving on an incorrect road. Such errors can be prevented by blocking the GPS signal, which eliminates the intervention of the GPS signal and allows the car navigation system 30 to perform processing to align with the map, thus suppressing the occurrence of a discrepancy in the vehicle's position.

[0058] Furthermore, by enabling the sampling timer interrupt, interrupt handling routines (I201~I204) can be executed, which increment and save the timer variable T3 each time a predetermined time has elapsed.

[0059] Specifically, the sampling timer interrupt handling routine starts processing (I201) when an interrupt occurs from the timer in the arithmetic unit 12. Regardless of the flow or state of the main routine, the sampling timer interrupt handling routine is always processed when a timer interrupt occurs.

[0060] When an interrupt is detected (I201), the timer variable T3 is incremented (added) and the result (T3 = T3 + 1) is saved (I202). Furthermore, the timer variable T4 is incremented (added) and the result (T4 = T4 + 1) is saved (I203). With this, the interrupt handling is completed and the program returns to the main routine step that was being processed immediately before executing the interrupt handling routine (I204).

[0061] As mentioned above, when the car navigation system 30 is driving at a predetermined speed (V1) or higher, and the car navigation control device 32 is set to TV viewing mode, an error occurs if the vehicle position information obtained based on the route vehicle travel information SG2 and GPS positioning information is determined to be different for a continuous period of t3. Therefore, the main routine performs the processing from step M105 to step M116.

[0062] After enabling interrupts for vehicle information acquisition and sampling timer measurement (M104), the timer variable T3, which is measuring the elapsed time, is cleared (T3=0) (M105).

[0063] In the following step M106, the car navigation control device 32 determines whether or not the TV viewing mode is still active. If the TV viewing mode is active, there is a possibility that the vehicle position information obtained based on the vehicle travel information SG2 and GPS positioning information may be inaccurate, so the processing from step M107 onwards is performed. If the TV viewing mode is not activated in the car navigation control device 32, the GPS signal is commanded to pass to the car navigation 30 (M115), and the process returns to step M105. This is because, if the car navigation control device 32 is not in TV viewing mode, there is no need to consider the discrepancy between the vehicle position information based on the vehicle travel information SG2 and GPS positioning information.

[0064] In step M107, it is determined whether the speed (SpNow) of vehicle 20 is V1 or greater. This determination is not limited to using the vehicle speed (SpNow). If the vehicle speed (SpNow) obtained in step I105 of the interrupt processing routine for acquiring vehicle information is less than V1, the car navigation system 30 does not compare the vehicle position information obtained based on the vehicle travel information SG2 and GPS positioning information, and the car navigation timer TC is reset. Therefore, even if the GPS control device 10 transmits a GPS signal to the car navigation system 30, the car navigation system 30 does not perform the comparison of the vehicle position information, so the GPS signal is passed through (M115) and the process returns to step M105. If it is determined that the vehicle speed of vehicle 20 is V1 or greater, monitoring must continue, so the process from step M108 onwards is performed.

[0065] In step M108, it is determined whether the vehicle 20 is decelerating too much. If it is decelerating too much (Vdwn=1), the GPS signal is blocked or the vehicle is rendered unable to acquire a position (M116), and the process returns to step (M105).

[0066] In step M108, if it is determined that the system is not decelerating excessively (Vdwn=0), then in M109, it is determined whether the timer variable T3 has reached a predetermined time t3'. In cases where there is a continuing discrepancy in vehicle position information based on vehicle driving information SG1 and transit vehicle driving information SG2, which occurs because the car navigation control device 32 is running, the car navigation system 30 determines that an error has occurred when the t3 period has elapsed. However, t3' is the upper limit value at which no error occurs. The t3' time is less than the upper limit of the t3 period, taking into account the state where the processing time of the car navigation system 30 or the car navigation control device 32 program is not uniform and the time accuracy error due to individual hardware differences, based on the timer variable T3. If it is determined that t3' has not been reached, then in order to continue monitoring, a command is issued to the car navigation system 30 to pass the GPS signal (M114), and the process returns to step M106.

[0067] If it is determined that time t3' has been reached, the error avoidance process from step M110 onward is executed. The error avoidance process first clears the timer variable T4, then blocks the GPS signal or makes positioning impossible (M111), monitors the progress of the timer variable T4, and maintains the state of blocking the GPS signal or making positioning impossible until a predetermined period of t4 is reached (M112).

[0068] Error avoidance is performed by blocking the GPS signal or making it impossible to position for a period of t4, as illustrated in Figure 7 (steps M111-M112). When the GPS signal is blocked or made impossible to position for a period of t4, the car navigation system 30 does not compare the vehicle position information based on the vehicle travel information SG2 and the GPS positioning information, and the car navigation timer TC of the car navigation system 30 is reset and does not recognize it as an error, thus avoiding the error. The t4 period is set to be the same as or longer than the t5 period, during which the car navigation system 30 does not perform error processing due to the GPS signal being blocked or made impossible to position, and resets the car navigation timer TC. Preferably, the t4 period is longer than the minute time period t5. This is because the car navigation system 30 can reliably reset the car navigation timer TC, and the timer variable T3 of the GPS control device 10 can be synchronized with the car navigation timer TC. After avoiding errors, the GPS signal is passed to the car navigation system 30 (M113), and the process returns to step M105. While the car navigation control device 32 is running TV viewing mode, the process from steps M105 to M112 is repeated.

[0069] The following describes an embodiment applicable when GPS positioning information is acquired by the GPS control device 10, and the GPS signal is interrupted or becomes unavailable due to external factors.

[0070] In the car navigation system 30, if the GPS signal is interrupted or positioning becomes impossible due to external factors, the car navigation timer TC is reset, and when positioning becomes possible again using the GPS signal, and when it is detected that the vehicle position information obtained based on the route vehicle travel information SG2 and the GPS positioning information is different, the t3 period is started to be measured.

[0071] On the other hand, the GPS control device 10 acquires GPS positioning information via the CAN input unit 17 and determines whether or not vehicle position information has been acquired, thereby detecting the timing for resetting the car navigation timer TC. By simultaneously resetting the timer variable T3 of the GPS control device 10, it becomes possible to synchronize with the error detection timing of the car navigation system 30. Compared to the case where the GPS control device 10 does not acquire GPS positioning information, it may be possible to reduce the number of times the GPS signal is forcibly blocked or positioning becomes impossible during the t4 period by the GPS control device 10. Reducing the number of times the GPS signal is forcibly blocked or positioning becomes impossible by the car navigation control device 32 has the effect of suppressing the deviation of the vehicle display position in the car navigation system 30.

[0072] Figures 10, 11, 12, and 13 are other examples of flowcharts in the GPS control device 10 that avoid errors caused by the accumulation of discrepancies between vehicle position information obtained based on transit vehicle travel information SG2 and GPS positioning information. The flowcharts are not limited to those shown above, and other flowcharts that show similar effects may be used. Figure 10 is an example of a flowchart of the main routine when monitoring GPS positioning information in the GPS control device 10. Figure 11 is an interrupt processing routine that saves vehicle travel information SG1 output from the vehicle 20 or transit vehicle travel information SG2 output from the car navigation control device 32. Figure 12 is an interrupt processing routine that determines whether the car navigation control device 32 is running, increments and saves a timer variable T3 each time a predetermined time has elapsed, and determines whether GPS positioning has been impossible for a predetermined time. Figure 13 is a GPS positioning information acquisition interrupt processing routine.

[0073] When monitoring GPS positioning information, the car navigation system 30 must either connect directly to the CAN bus 50, as shown by the dashed lines in Figures 1 and 2, to monitor GPS positioning information, or monitor GPS positioning information from the GPS signal received from the GPS antenna 40. The GPS control device 10 is equipped with a CAN bus receiver 17 that receives vehicle information from the CAN bus 50, and must be connected directly to the CAN bus 50, as shown by the dashed lines in Figures 1 and 2.

[0074] The flowchart of the main routine shown in Figure 10 shows that immediately after starting (M201), the GPS signal input from the GPS antenna 40 is set to pass to the car navigation system 30 (M202). Note that when the GPS control device 10 is not operating, it is necessary to initialize it to a state where the GPS signal from the GPS antenna 40 passes to the car navigation system 10. Next, interrupts for vehicle information acquisition, GPS positioning information acquisition, and sampling timer measurement are enabled (M203~M205). By enabling the vehicle information acquisition interrupt, the interrupt processing routines (I301~I315) that save the vehicle driving information SG1 output from the vehicle 20 and the vehicle driving information SG2 output from the car navigation control device 32 become executable. In the explanations of Figures 10, 11, 12, and 13, the vehicle driving information SG1 is exemplified as a driving pulse signal, but the vehicle driving information SG1 may be vehicle speed data obtained from CAN etc. 50 instead of a driving pulse signal. Here, the pulse period of the driving pulse signal represents the time it takes to travel a predetermined distance. Therefore, a shorter pulse width results in a faster speed, while a longer pulse width results in a slower speed.

[0075] Specifically, the vehicle information acquisition interrupt processing routine starts processing (I301) when it detects a driving pulse signal from the vehicle 20 or the car navigation control device 32. The driving pulse signal is detected when the signal potential changes from the reference level. The same applies hereafter. Note that the timing of the driving pulse signal detection is just an example; it may also be detected when the potential changes from the reference level and then returns to the reference level, or the driving pulse signal may be detected by acquiring both the potential change from the reference level and the subsequent potential change when returning to the reference level. Regardless of the flow or state of the main routine, the driving pulse signal is always acquired when it is output from the vehicle 20 or the car navigation control device 32. When a driving pulse signal is detected, the potential of the vehicle driving information SG1 and the potential of the transit vehicle driving information SG2 are saved (I302~I303). Next, the interval between the previously acquired pulse and the currently acquired pulse of the driving pulse signal is calculated to acquire the current vehicle speed (SpNow), and saved together with the previous vehicle speed (SpBf) (I304~I305). By using the previous vehicle speed (SpBf) and the current vehicle speed (SpNow), it is determined whether or not over-deceleration is occurring (I306). If over-deceleration is occurring, the over-deceleration flag is set (Vdwn=1) (I307), and if over-deceleration is not occurring, the over-deceleration flag is reset (Vdwn=0) (I308).

[0076] Next, the system determines whether the vehicle travel information SG1 and the route vehicle travel information SG2 obtained by the vehicle information acquisition interrupt processing routine are equal (I309). If they are equal, the car navigation control unit startup confirmation counter C1 is incremented (I310). If they are not equal, the counter C1 is cleared (I311).

[0077] Whether the vehicle driving information SG1 and the transit vehicle driving information SG2 are equal can be determined by whether their respective signal levels show the same H (high) or the same L (low) at the same time, thereby determining whether the car navigation control device 32 is activated. Alternatively, it can also be determined by whether the pulse widths of the vehicle driving information SG1 and the transit vehicle driving information SG2 are the same during the same time period. Furthermore, the car navigation control device 32 can also be determined by detecting that the car navigation control device indicates to the car navigation 30 that the vehicle 20 is stopped during period T1 (which is equivalent to outputting a vehicle stop status signal to the car navigation 30), and that during period T2, it outputs the vehicle driving information SG2 for both periods T1 and T2 to the car navigation 30.

[0078] When the condition in which the vehicle driving information SG1 and the vehicle driving information via SG2 are equal exceeds a predetermined number of times (c1) (I312), the car navigation control device 32 is determined to be not running and the car navigation control device startup flag is reset (I313). If the vehicle driving information SG1 and the vehicle driving information via SG2 are not equal, the car navigation control device 32 is immediately determined to be running and the car navigation control device startup flag is set (I314).

[0079] This completes the interrupt handling process, and the program returns to the main routine step that was being processed immediately before executing the interrupt handling routine (I315).

[0080] By enabling the GPS positioning information acquisition interrupt routine, GPS positioning information can be acquired from the vehicle 20 at the time of GPS positioning, and the interrupt processing routines (I501~I503) that set the GPS acquisition flag (GP) become executable. GPS positioning information includes vehicle position information (GPS positioning information) obtained by acquiring GPS signals and performing GPS positioning, and information obtained when the GPS signal is significantly attenuated and cannot be acquired due to factors such as GPS radio waves being blocked in tunnels, or when positioning is impossible (hereinafter referred to as "GPS positioning failure information").

[0081] Specifically, the GPS positioning information acquisition interrupt routine starts interrupt processing (I501) when it receives GPS positioning information or GPS positioning failure information. Regardless of the flow or state of the main routine, GPS positioning information or GPS positioning failure information is always acquired via the CAN or other receiving unit 17 when transmitted from the vehicle 20. When GPS positioning information is acquired, the GPS acquisition flag GP in the storage memory is set to "1" (GP=1), and when GPS positioning failure information is acquired, the GPS acquisition flag GP in the storage memory is set to "0" (GP=0), and the information is saved (I502). Once the acquisition of GPS positioning information or GPS positioning failure information is complete, the interrupt processing ends, and the system returns to the main routine step that was being processed immediately before executing the interrupt processing routine (I503).

[0082] Furthermore, by enabling the sampling timer interrupt, an interrupt processing routine (I401~I416) becomes executable that determines whether the car navigation control device 32 is running and increments and saves timer variables T3 and T4 each time a predetermined time has elapsed.

[0083] Specifically, the sampling timer interrupt handling routine starts processing (I401) when an interrupt occurs from the timer in the arithmetic unit 12. Regardless of the flow or state of the main routine, the sampling timer interrupt handling routine is always processed when a timer interrupt occurs.

[0084] When an interrupt is detected (I401), the timer variable T3 is incremented (added) and the result (T3 = T3 + 1) is saved (I402). Furthermore, the timer variable T4 is incremented (added) and the result (T4 = T4 + 1) is saved (I403).

[0085] Furthermore, if the GPS positioning is unavailable for t6 hours, the GPS unavailable status flag is set (GPSOUT=1). t6 hours is the period during which the car navigation system 30 does not perform error processing due to the GPS signal being blocked or positioning becoming unavailable, and the car navigation timer TC is reset. Typically, t6 hours is used to avoid frequent error detection when the GPS signal is blocked or positioning becomes unavailable in short intervals, such as when the vehicle 20 enters a tunnel or between tall buildings.

[0086] The GPS positioning information acquisition interrupt processing routine determines whether the acquired GPS information GP is in an acquired state (GP=1) or an unacquired state (GP=0) (I404). If it is in an unacquired state, the GPS positioning confirmation timer T6 is incremented (I405). If the state in which GPS information cannot be acquired exceeds t6 hours (I407), it is determined that the state in which positioning cannot be performed using GPS continues, and the GPS unacquired state flag is set (GPSOUT=1) (I408). In step I404, if it is determined that the GPS information GP is in an acquireable state, the GPS positioning confirmation timer T6 is cleared (I406), and it is determined that positioning can be performed using GPS, and the GPS unacquired state flag is reset (GPSOUT=0) (I409).

[0087] This completes the interrupt handling process, and the program returns to the main routine step that was being processed immediately before executing the interrupt handling routine (I410).

[0088] As mentioned above, when driving at a predetermined speed (V1) or higher, if the car navigation control device 32 is set to TV viewing mode, an error occurs if the vehicle position information based on the route vehicle travel information SG2 and GPS positioning information is determined to be different for a continuous period of t3, or if accurate position information cannot be obtained continuously. Therefore, the main routine performs the processing from step M206 to step M218. After enabling interrupts for vehicle information acquisition and sampling timer measurement (M205), the timer variable T3, which is measuring the elapsed time, is cleared (T3=0) (M206).

[0089] In the following step M207, the car navigation control device 32 determines whether or not the TV viewing mode is still active. If the TV viewing mode is active, the system needs to continue monitoring because there is a possibility that the vehicle position information based on the vehicle travel information SG2 and GPS positioning information may be accumulating in a discrepancy, so the process in step M208 is performed. If the TV viewing mode is not activated in the car navigation control device 32, the system commands the GPS signal to pass to the car navigation system 30 (M217) and returns to step M206. This is because, when the car navigation control device 32 is not in TV viewing mode, there is no need to consider the discrepancy between the vehicle position information based on the vehicle travel information SG2 and GPS positioning information from the GPS signal.

[0090] In step M208, it is determined whether the vehicle speed (SpNow) of vehicle 20 is V1 or greater. If the vehicle speed (SpNow) obtained in step I305 of the interrupt processing routine for acquiring vehicle information is less than V1, the car navigation system 30 does not compare the vehicle position information based on the vehicle travel information SG2 and the GPS positioning information, and the car navigation timer TC is reset. Therefore, even if the GPS control device 10 sends a GPS signal to the car navigation system 30, the car navigation system 30 does not perform the comparison of the vehicle position information. So, the GPS signal is passed towards the car navigation system 30 (M217) and the process returns to step M206. If it is determined that the vehicle speed of vehicle 20 is V1 or greater, monitoring must continue, so the process from step M209 onwards is performed.

[0091] In step M209, it is determined whether or not t6 hours have elapsed since the GPS positioning information could not be received. If GPS positioning information can be received, the process from step M210 onwards is performed because there is a possibility that the vehicle position information obtained based on the transit vehicle travel information SG2 and the GPS positioning information may be inaccurate and accumulate, so monitoring must continue. If GPS positioning information cannot be received, a command is issued to the car navigation system 30 to receive the GPS signal (M217), and the process returns to step M206. This is because, when GPS positioning information cannot be received, there is no need to consider the discrepancy between the vehicle position information based on the transit vehicle travel information SG2 and the GPS positioning information obtained from the GPS signal.

[0092] In step M210, it is determined whether the vehicle 20 is decelerating too much. If it is decelerating too much (Vdwn=1), the GPS signal is blocked or the vehicle is rendered unable to acquire a position (M218), and the process returns to step (M206).

[0093] In step M210, if it is determined that the system is not decelerating excessively (Vdwn=0), then in M211, it is determined whether the timer variable T3 has reached a predetermined value t3' time. Because the car navigation control device 32 is running, if there is a discrepancy between the vehicle position information based on the vehicle driving information SG1 and the vehicle driving information SG2, the car navigation system 30 determines that an error has occurred after the t3 period has elapsed. t3' time is the upper limit value at which no error occurs. t3' time is less than the upper limit of the t3 period, taking into account the state where the processing time of the car navigation system 30 or the car navigation control device 32 program is not uniform and time accuracy errors due to individual hardware differences, based on the timer variable T3. If it is determined that t3' time has not been reached, then in order to continue monitoring, a command is issued to the car navigation system 30 to pass the GPS signal (M216), and the process returns to step M207.

[0094] If it is determined that time t3' has been reached, the error avoidance process from step M212 onwards is executed. The error avoidance process first clears the timer variable T4 (M212), then blocks the GPS signal or makes positioning impossible (M213), monitors the progress of the timer variable T4, and maintains the state of blocking the GPS signal or making positioning impossible until a predetermined value t4 period is reached (M214).

[0095] Error avoidance is performed by blocking the GPS signal or making it impossible to position for a period of t4, as illustrated in Figure 7 (steps M213-M214). When the GPS signal is blocked or made impossible to position for a period of t4, the car navigation system 30 does not compare the vehicle position information based on the vehicle travel information SG2 and the GPS positioning information, and the car navigation timer TC of the car navigation system 30 is reset, and the system does not recognize it as an error, thus avoiding the error. The t4 period is set to be the same as or longer than the t5 period, during which the car navigation system 30 does not perform error processing due to the GPS signal being blocked or made impossible to position, and the car navigation timer TC is reset. Preferably, the t4 period is longer than the minute time period t5. This is because the car navigation system 30 can reliably reset the car navigation timer TC, and the timer variable T3 of the GPS control device 10 can be synchronized with the car navigation timer TC. After avoiding errors, the GPS signal is passed to the car navigation system 30 (M215), and the process returns to step M206. While the car navigation control device 32 is running TV viewing mode, the process from steps M206 to M214 is repeated.

[0096] The following is another example of signal processing by the GPS control device 10 in a car navigation control device 32 that enables simultaneous viewing of television and navigation operation, in which errors caused by the accumulation of discrepancies between vehicle position information obtained based on transit vehicle travel information SG2 and GPS positioning information. There is a car navigation system 30 that changes the t3 period according to the vehicle speed. When the vehicle speed is high, it travels a long distance in a short time, so if the t3 period is not shortened and error processing is not performed, the vehicle position deviation in the car navigation system 30 will become large. Accordingly, it is necessary to shorten the t3' time set in the GPS control device 10. The t3' time must be shorter than the t3 period. To address the above case, the GPS control device 10 can create a table that changes the t3' time according to the speed, and by referring to the speed as needed and changing the t3' time, it is possible to suppress the position deviation of the vehicle 20 in the car navigation system 30. [Industrial applicability]

[0097] The GPS control device according to the present invention is used in conjunction with a device that can be attached to a vehicle such as an automobile and process vehicle driving information as a signal to enable simultaneous viewing of a television or the like and navigation functions while driving. [Explanation of Symbols]

[0098] 10 GPS control unit 12 Arithmetic section 13 Storage section 14 GPS signal input / output section 141 GPS signal processing unit a 142 GPS signal processing unit b 143 GPS signal processing unit c 144 GPS signal processing unit d 145 GPS signal processing unit 15. Vehicle Driving Information Input Unit 16 Vehicle travel information input unit 17 CAN and other input section 18 Bus Line 20 vehicles 22. Automotive Electronic Control Unit (Automotive ECU) 30. Car navigation system (car navigation) 32. Car navigation control unit 40 GPS antennas 440 Dummy GPS Antenna 442 Jamming Antenna 50 CAN etc. (CAN or other vehicle data bus lines) 6th Front Camera 62 Rear camera 64 Illuminance Sensors 66 Front Sonar 68 Rear Sonar SG CAN etc. signal SG1 Vehicle Operation Information SG2 Unprocessed vehicle travel information or calculated vehicle travel information (vehicle travel information via route) SG3 GPS received signal SG4 GPS output signal T1 first period T2 second period Time until an error occurs in the t3 car navigation system t3' Maximum time limit to avoid errors in car navigation systems t4 GPS signal interruption period in GPS control device t5 The time during which the GPS signal is interrupted or positioning is impossible, and the car navigation timer TC is reset. t6 Period during which the car navigation system 30 does not perform error processing and resets the car navigation timer TC due to the GPS signal being interrupted or positioning becoming impossible. TC Car Navigation Timer Timer for managing error occurrences in the T3 GPS control unit Timer for managing GPS signal interruption, etc., provided in the T4 GPS control unit. V1 Lower limit of vehicle speed for comparing vehicle driving information and GPS positioning information.

Claims

1. A GPS signal control device that is connected between a vehicle and a car navigation system, and is added as an auxiliary device to a car navigation control device that enables viewing of video while the vehicle is in motion, A vehicle driving information input means for inputting vehicle driving information output from the vehicle to the car navigation control device, A means for inputting transit vehicle travel information that inputs transit vehicle travel information output to the car navigation system via the car navigation control device, A GPS signal input means for receiving GPS signals from a GPS antenna, Calculation means and A storage means for storing the aforementioned vehicle travel information and the aforementioned route vehicle travel information, A GPS signal control output means controls the GPS signal based on the calculation result of the calculation means and outputs it to the car navigation system, Equipped with, The aforementioned calculation means is A comparison means for comparing the aforementioned vehicle travel information and the aforementioned route vehicle travel information, A determination means for determining whether or not the car navigation control device is operating in video viewing mode based on the results of the above comparison, An error avoidance means for avoiding the occurrence of errors in the aforementioned car navigation system, Equipped with, The aforementioned error avoidance means is, If the car navigation control device is determined to be operating in video viewing mode, it will perform monitoring of the elapsed time to avoid the error. The error recognition of the car navigation system is avoided by blocking the GPS signal for a predetermined period or rendering it unable to position for a predetermined period before the elapsed time reaches a predetermined period. A GPS control device characterized by the following.

2. The calculation means, Between the vehicle position information based on the aforementioned vehicle travel information and the GPS positioning information based on the GPS signal, If the vehicle location information for period t3 continues to differ, or If discrepancies in vehicle location information exceed a predetermined tolerance value within the t3 period are detected for a predetermined duration or for a predetermined number of times, Under the conditions under which an error is determined to have occurred in the car navigation system, An error avoidance means that monitors the elapsed time after the condition is met and avoids the car navigation system recognizing an error by blocking the GPS signal for a period of t4 or rendering it unable to position before the elapsed time reaches period t3. A GPS control device according to claim 1, characterized by comprising the following:

3. The calculation means, The system includes a determination means for determining whether the vehicle speed is above a predetermined speed based on the aforementioned vehicle driving information. If the vehicle speed falls below a predetermined speed during the aforementioned elapsed time monitoring, the monitoring will be stopped, the elapsed time will be reset, and the monitoring will not be resumed until the vehicle speed returns to or above the predetermined speed. A GPS control device according to claim 2, characterized by the following:

4. If the GPS antenna of the vehicle fails to acquire GPS signals from positioning satellites and becomes unable to determine position, The calculation means, The monitoring of the elapsed time is stopped, the elapsed time is reset to its initial value, and the monitoring of the elapsed time is not resumed until the GPS antenna receives a GPS signal again and positioning becomes possible. A GPS control device according to claim 2, characterized by the following:

5. The calculation means, Based on the changes in the aforementioned vehicle driving information, it is determined whether or not an over-deceleration has occurred in which the vehicle speed suddenly decreases below a predetermined standard. A GPS control device according to claim 1 or claim 2, characterized by the above.

6. The calculation means, The error avoidance means is repeatedly executed while the vehicle travel information indicating that the vehicle is stopped despite being in motion is being continuously or intermittently transmitted by the car navigation control device. A GPS control device according to claim 1 or claim 2, characterized by the above.

7. It is equipped with a GPS signal amplifier that prevents the GPS signal from attenuating. A GPS control device according to claim 1 or claim 2, characterized by the above.

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