JPH07117577B2 - In-vehicle position detection device using a roadside beacon - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted position detecting device using a roadside beacon, and more particularly, when a signal from a roadside beacon is received, accurate position detection is performed in consideration of the reception level of the signal. The present invention relates to a vehicle-mounted position detection device improved so that it can be performed.

[0002]

2. Description of the Related Art Various types of navigation devices have been proposed and put into practical use for supporting the running of vehicles on uncharted land. Conventional navigation devices generally
A position detection unit that detects the current position of the vehicle based on the outputs from the distance sensor and the azimuth sensor, a map memory including a CD-ROM, a display device, and the current position of the vehicle detected by the position detection unit. And a control unit for reading a road map including the above from the map memory and displaying it on the display device.

By the way, in such a navigation device, the current position of the vehicle on the display device greatly increases from the actual position due to an increase in the traveling distance due to the errors which the vehicle speed sensor and the direction sensor necessarily have. There is a risk of slipping. Further, when traveling near a railway line or the like, a large error is likely to occur in the direction sensor due to the magnetic effect.

For the purpose of solving such a problem, installation of a roadside beacon has been proposed. The roadside beacon includes beacon antennas arranged at predetermined distances in a road traffic network, and radiates a signal including position data and road direction data from the beacon antenna in a relatively narrow range. A vehicle traveling on the road can receive this signal and capture it in the navigation device to calibrate the vehicle's current position and orientation to the correct one.

By the way, in order to effectively utilize the roadside beacon, it is desirable to add not only position data and road direction data but also the following data to the signal radiated from the beacon antenna. That is, details including traffic information such as road congestion around the location where the beacon antenna is installed, construction, and other road usage conditions, housing arrangements around the location where the beacon antenna is installed, and personal names. In order to utilize roadside beacons, it is preferable to add additional data such as special map information, road map information covering a certain wide range including locations where beacon antennas are installed, etc. to the signal.

However, when such additional data is also radiated from the beacon antenna, it is necessary to widen the signal propagation area and widen the signal receivable area so that the additional data can be reliably received. However, if the propagation area of the signal is expanded, it becomes impossible to accurately perform the original function of calibrating the current position of the vehicle to the installation position of the beacon antenna by receiving the signal when it comes directly below the installation position of the beacon antenna. Encounter points.

In order to solve such a problem, the applicant of the present application has already proposed the roadside beacon system of Japanese Patent Application No. 62-154922 and Japanese Patent Application No. 62-255569. In the roadside beacon system according to the prior application, a beacon antenna is composed of two antenna elements having different main radiation directions, and various data components are PSK, FSK, GMS.
A signal put by a first modulation method such as K or ASK modulation is divided into two parts, and position data is put by applying amplitude modulation of opposite phases to the divided signal, and the first modulation component is made in phase with each antenna element. The power is supplied so that the amplitude modulation component is extracted on the vehicle side to detect the position, and the first modulation component is extracted to restore various data.

[0008]

By the way, in the roadside beacon system, in general, the signal radiated from the beacon antenna is apt to cause fading, and the reception level of the signal in the in-vehicle receiver fluctuates and the phase also fluctuates, A problem was discovered that could lead to false detection of position.

Further, since the propagation area of the signal from the beacon antenna is wide, radio waves from the beacon antenna provided on the parallel running road on the elevated road leak and the signal is received on the road under the elevated road. It was also found that incorrect position detection could be performed based on this. Therefore, the present invention is an in-vehicle position detection device that receives a roadside beacon signal to perform position detection, is not affected by fading, and prevents erroneous position detection due to reception of a signal from an unplanned beacon antenna. A vehicle position detecting device is provided.

The present invention, in one aspect, comprises a first modulation method.
The signals modulated by the equation are bisected and the bisected signals are
Are modulated by a second modulation method of opposite phase, and these signals are
The modulation components of the
When received, the receiving means for receiving the radiated signal, and when the level of the carrier wave of the received signal received by the receiving means is equal to or higher than a predetermined level, the first signal is set to be lower than the predetermined level. In the case of, the level discrimination means for outputting the second signal, the receiver
Modulated by the first modulation method from the received signal received at the stage
Detected signal and based on the phase of this signal the reference clock
From the received signal received by the receiving means
The signal modulated by the second modulation method is detected and
Compare the phase with the created reference clock and
The second phase of the signal modulated by the modulation method is a phase determining means for determining whether the positive phase or reverse phase, the time count is initiated by the on-edge of the second signal supplied from the level judgment means relative to the second An off-timer for deriving an off-output when a continuous time of signals reaches a predetermined off-time, the first signal is given from the level discriminating means, or the off-timer is turned off although the first signal is not given. When there is no output , the phase determining means adopts the phase determined by the phase determining means as the confirmed phase, and the phase adopted by the phase determining means is inverted to the opposite phase.
In response to this, the vehicle's current position is
Position determining means for determining the installation position of the user.

[0011] The invention, in another aspect, prior Symbol phase determining means, said phase discriminating means phase that is determined by the
When continuously output for a predetermined time , the phase is adopted as the definite phase.
Or octopus invention, in yet another aspect, the phase determined hand
After the step adopts the definite phase, the position determination means is
Before determining the position off the output of the off-timer there
On the basis of the fact that the phase decision means has adopted, a cancellation means for canceling the phase adopted by the phase decision means is further included.
It is what

[0012]

When the propagation area of the signal radiated from the beacon antenna is wide, the signal received by the vehicle-mounted receiving device (carrier
The reception level of ( wave) changes due to fading. Therefore, the level of the received signal is, for example, -65 dB to -70 d.
When the level is lower than B, the first detected from the received signal.
Modulation signal modulated by the modulation method of 2 (for example, 1 kHz
The phase determination of the AM signal) is not performed, and the phase determination of the AM signal is performed only when the level of the received signal is higher than that.
That is, the phase determination of the modulated signal modulated by the second modulation method is performed only when the level determining means outputs the first signal indicating that the level of the received signal is equal to or higher than the predetermined level.

Even when the level discriminating means outputs the second signal indicating that the level is less than the predetermined level, if the output time of the second signal is less than the predetermined off time, The phase of a predetermined modulation signal is continuously determined. As a result, even if the level of the received signal drops momentarily, it is possible to reduce the possibility of misidentifying the direction by canceling the phase determination process based on it. Also, by not making the off time too long, it is possible to prevent erroneous detection of the position due to reception of a signal from an unscheduled beacon antenna such as a beacon antenna on an elevated railroad.

According to the present invention, the phase is determined when the same phase continues for the time required for the predetermined determination. By doing so, it is possible to eliminate the erroneous determination of the phase due to the instantaneous phase change. On the other hand, by properly setting the time required for confirmation, it is possible to reduce the number of detection omissions in which the phase cannot be determined and position detection cannot be performed.

Further, according to the present invention, the phase is once determined.
Even after the phase detection, the phase that was once confirmed is canceled based on the fact that the off output of the off timer is derived before the position detection, so erroneous phase confirmation processing can be prevented. Accurate position detection can be performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an outline of position detection and direction identification using roadside beacons. Figure 1A
As shown in, a beacon antenna 2 is installed on the road side of the road 1. A signal is radiated from the beacon antenna 2 toward the road 1.

As shown in FIG. 1C, the signal radiated from the beacon antenna 2 is divided into two and divided into a signal in which various data are added by the first modulation method (GMSK, PSK, FSK, ASK modulation, etc.). An AM signal having a phase opposite to that of the other signal, for example, which is amplitude-modulated at 1 kHz is added to the signal. The position data is 1k
It may be superimposed by an AM signal other than Hz. Alternatively, they may be superimposed using another modulation method.

Therefore, the emission zone of the AM signal is shown in FIG. 1A.
As described above, for example, the beacon antenna 2 radiates an in-phase signal in the right direction and an in-phase signal in the left direction. The signal emitted from the beacon antenna 2 is received by the receiver mounted on the vehicle running on the road 1. The reception level of the signal is as shown in FIG. 1B, for example. That is, for the data signal component of the received signal, the received level of a predetermined electric field strength distribution that spreads around the beacon antenna 2 is obtained. On the other hand, regarding the AM signal component, the reception level of the electric field distribution that causes a sharp drop in the main radiation direction boundary line between the in-phase signal and the anti-phase signal can be obtained. Therefore, in the vehicle traveling on the road 1, when the reception level of the received AM signal component changes and the level sharply drops, it can be determined that the position is directly below the beacon antenna 2. That is, it can be determined that the point of the position data being received has arrived.

Further, in FIG. 1A, when the traveling direction of the vehicle is a, the AM signal is first the signal of the same phase is received, and then the AM signal of the opposite phase is received after the abrupt level decrease. On the other hand, when the traveling direction of the vehicle is b, first, the AM signal of the opposite phase is received, and after the sudden decrease of the level, the in-phase A signal is received.
The M signal is received. Therefore, in the reception of the AM signal, the traveling direction of the vehicle can be identified depending on whether the phase of the received signal changes from the same phase to the opposite phase or from the opposite phase to the same phase.

As shown in FIG. 1C, it is determined whether the AM signal is in-phase or out-of-phase with respect to the head of the data frame of the data signal.
It is determined whether the AM signal is synchronized at the rising edge or the falling edge. FIG. 2 is a block diagram showing a configuration example of the vehicle-mounted position detection device according to this embodiment. The vehicle-mounted antenna 11 receives the signal radiated from the beacon antenna 2, and the receiver 12 detects and amplifies the signal. This receiver 1
The output of 2 is given to the position detection device 20.

The position detecting device 20 includes a data demodulator 2
1, sync detector 22, 1 kHz reference clock generator 2
3, a 1 kHz detector 24, a phase determiner 25, a CD detector 26 and a CPU 27 are provided. The data demodulator 21 demodulates the data of the received signal, and the synchronization detector 22 detects the synchronization timing of the demodulated data. Then, based on this synchronization timing, 1 kHz
In the reference clock generator 23, a reference clock of 1 kHz synchronized with the data frame is created. This clock is, for example, a clock that rises in synchronization with the beginning of the data frame.

On the other hand, the output of the receiver 12 is given to the 1 kHz detector 24, and the 1 kHz AM signal is extracted from the received signal. This AM signal is given to the phase determiner 25,
The phase is compared with the reference clock created above. 1k
The reference clock generated by the Hz reference clock generator 23 is a signal whose rising edge is synchronized with the beginning of the data frame as described above. Therefore, when the output of the 1 kHz detector 24 is in phase with the reference clock, the phase determiner 25 determines that the received signal is a signal received in the in-phase region. When the output of the 1 kHz detector 24 is in the opposite phase to the reference clock, it is determined that the received signal is the signal detected in the opposite phase region. The output of the phase determiner 25 is high level when in phase and low level when in phase, and its output is given to the CPU 27.

Further, the output of the receiver 22 is the CD detector 2
Given to 6. In the CD detector 26, the carrier wave reception level of the reception signal is a predetermined constant level (for example, -70).
Any value in the range db to -65 dB, for example -70
It is a circuit for detecting whether or not it is not less than dB). When the reception level of the carrier wave is, for example, the reference level −70 dB or more, the output of the CD detector 26 becomes high level, and conversely, when the reception level of the carrier wave is less than the reference level −70 dB,
The output of the CD detector 26 becomes low level. The output of the CD detector 26 is given to the CPU 27.

The CPU 27 executes the processing described later, and detects the position and the traveling direction of the vehicle based on the output of the phase determiner 25 and the output of the CD detector 26.
The output of the CPU 27 is given to the display controller 28,
The display control unit 28 controls the display of the display 29. FIG. 3 shows the received signal level, CD in this embodiment.
Output of detector 26, output of phase determiner 25 and CPU
27 is a specific example of received data representing the relationship between the position and direction detection signals detected by 27.

FIG. 4 is a flow chart showing an outline of a processing procedure for detecting the position and direction in the CPU 27. Next, referring to FIGS. 2, 3 and 4, the CPU 27 determines that the CD is ON when the output of the CD detector 26 is continuously high for a certain ON time “n0” or more. (Step S1).

Next, when the output of the phase determiner 25 is determined in the CD-ON state and the positive phase or the negative phase continues for a predetermined initial phase confirmation time "n2" or longer, that phase is the initial phase. It is determined that there is (step S2). Then, the determination phase of the phase determiner 25 is inverted at a certain point in time. The CPU 27 determines that the phase has been inverted when the inverted phase continues for a predetermined inverse phase confirmation time "n3" (step S3).

Then, the inversion time is detected as the installation position of the beacon antenna 2 (see FIG. 1) from the initial phase determined in step S2 and the antiphase determined in step S3, and depending on the inversion direction. The direction is detected. If the output of the CD detector 26 becomes low for a predetermined off time “n1” or more within the phase determination time of steps S2 and S3, it is determined that the CD is off, and the processing from step S1 is performed. The initial phase and the like that are newly performed and determined so far are canceled.

As described above, only when the reception level of the carrier wave of the received signal is within a predetermined fixed level, for example, in the range of -70 dB or more, the phase determination and the phase inversion of the AM signal are detected. Therefore, as shown in FIG. 3, in a region where the received signal level fluctuates greatly due to fading, the output of the CD detector 26 frequently changes to high and low, and CD on is not judged. On the other hand, C
It is determined that D is on, and the phase is determined only within the range in which the reception level of the carrier wave is equal to or higher than a predetermined level. Therefore, an accurate determination result can be obtained.

5 and 6 are flow charts showing more detailed position and direction detection processing control in the CPU 27 (see FIG. 2). FIG. 7 is a diagram showing four counters necessary for performing the control of FIGS. The counter shown in FIG. 7 may be created by a program (software) or may be a hardware-configured counter.

The counter N0 is a CD ON determination counter. When the count value of the counter N0 becomes "n0", it is determined that the CD is on. Specifically, the count value "n0" is set to a value corresponding to, for example, 50 msec. The counter N1 is a counter for CD off determination. When the count value of the counter N1 becomes "n1", it is determined that the CD is off. Once the confirmed phase is canceled, the possibility of misidentifying the direction increases, so
Once the phase has been confirmed, it is not easily canceled,
The count value “n1” is a value corresponding to a somewhat long time (condition 1). On the other hand, the count value "n1" is set to "condition 1" described above so that the CD-on state is not erroneously determined by detecting a signal leaking from a beacon antenna arranged on a road running on a parallel elevated road. It is set to a value corresponding to the shortest possible time within the range that satisfies.

Specifically, the count value "n1" is set to a value corresponding to a time range of 200 msec to 2.5 sec. The counter N2 is a phase fixing counter. When the count value of the counter N2 becomes "n2", the initial phase is fixed. This count value "n2" is set to a relatively long time in order to enhance the stability with respect to the determination of the initial phase. For example, time 80-200mse
It is set to a value corresponding to c.

When the count value of the counter N2 becomes "n3" after the initial phase is fixed, the phase inversion is fixed. The count value "n3" is smaller than the count value "n2". This is because if the time required to determine the phase after the reversal is too long, the delay time from the reversal becomes long and the position detection error becomes large. Specifically, in this embodiment, the count value "n
3 ″ is set to a value corresponding to a time of 50 msec, for example.

Next, a description will be given according to the flow of FIGS. Every predetermined fixed time (for example, 10 ms),
Alternatively, every time the vehicle travels a certain distance (for example, 0.5 m), the CPU 27 executes the processing shown in FIGS. 5 and 6. First, it is determined whether the signal given from the phase detector 26 is high level or low level (step S).
11). At the high level, the counter N0 is incremented by 1 and the counter N1 is reset (step S
12). On the other hand, when the level is low, the counter N1 is +
1 and the counter N0 is reset (step S13).

Next, it is judged whether or not the CD-ON is set (step S14). Since CD ON is not set at the start of control, step S1
In step 5, it is determined whether the count value of the counter N0 is "n0" or more. When the count value of the counter N0 is "n0" or more, CD ON is set (step S16), and the process is returned. When the count value of the counter N0 is less than "n0", CD-ON is not set and this process is returned.

When it is determined in step S14 that the CD ON is set, it is determined whether or not the count value of the counter N1 is "n1" or more (step S17). If YES in step S17,
Since the level of the received signal has become equal to or lower than the predetermined level for a predetermined CD off time or longer, in that case, the phase determination process is repeated from the beginning. That is, 240 ms
Since the level of the received signal is, for example, −75 dB or less for ec to 2.5 seconds or more, in this case, even if the initial phase is once determined, the determination is canceled (reset) (step S18). ), And C
D-off is set (step S19). Then, this process is returned.

Next, in the case of NO at step S17, that is, when the level of the received signal becomes less than the predetermined level, that time is the CD off time (for example, 240 msec).
In the case of a short time shorter than (~ 2.5 sec), erroneous detection can be avoided as a whole by ignoring the decrease in the level of the received signal and continuing the phase determination process. So in this case,
It is determined whether the phase given by the phase determiner 25 (see FIG. 2) is the same as the previous phase (step S20).
If the phase determination signal is the same as the previous time, the counter N2 is +
1 (step S21). On the other hand, if the phase determination signal is inverted from the previous one, the counter N2 is reset (step S22).

Next, it is judged whether or not the initial phase has been decided. If the initial phase has not been finalized, it is determined whether the count value of the counter N2 is "n2" or more (step S24). If the count value of the counter N2 is "n2" or more, step S20 is performed. It is determined that the determined phase is the initial phase (step S25), and this process is returned. In this way, based on the count value “n2” of the counter N2, the time when the in-phase or anti-phase signal is predetermined, for example, 80 to 200 msec.
The initial phase is determined when the signals are continuously output. Therefore, when the phase fluctuates, the initial phase is not fixed, and the phase is fixed only when the phase becomes stable.

If NO at step S24,
This process is returned without initial phase being fixed.
In step S23, if the initial phase has been determined, then the phase is inverted and the counter N
It is determined whether the count value of 2 is "n3" or more (step S26). If the count value is "n3" or more, the phase inversion is confirmed (step S27). Then, the initial phase determined in step S25 and step S
The position of the beacon antenna and the direction of the road are calculated based on the phase inversion determined in step 27 (step S
28). As described above, the count value “n3” is shorter than the count value “n2”, for example, 5 times.
It is set to a value corresponding to 0 msec. By doing this, the time required to determine the phase after the determination can be shortened,
Since the delay time from the phase inversion can be shortened, it is possible to confirm the phase inversion while maintaining good position detection accuracy.

In the case of NO at step S26, the process of steps S27 and S28 is not performed and the process returns. FIG. 8 is a flowchart showing the display control of the display unit 29 by the display control unit 28 (see FIG. 2). Referring to FIG. 8, in display control unit 28, based on the signal from CPU 27, the current position of the vehicle (the installation position of the beacon antenna)
Is detected (step S3).
1).

Then, only when the position is detected, various data obtained from the demodulated received data are displayed on the display 29 (step S32). In this way, if the data is displayed only when the position is detected, only the meaningful information at that position is displayed based on the correct position detection. Therefore,
Only the correct and necessary data can be provided to the driver.

Of course, the demodulated various data may be always displayed on the display 29 regardless of whether or not the position is detected. FIG. 9 is a diagram for explaining another effect obtained by the present invention. Figure 9
As shown in Figure 3, the elevated road 3
2 is provided. It is also assumed that the beacon antenna 33 is installed on the elevated road 32. In such a case, the signal radiated from the beacon antenna 33 may be propagated not only on the originally intended elevated road 32 but also on the road 31 located below it.

In such a case, the vehicle 34 traveling on the road 31
Mistakenly received the signal from the beacon antenna 33,
There was a possibility of erroneous position detection. However, when the present invention is applied, when the radio wave radiated from the beacon antenna 33 is received by the vehicle 34 traveling on the road 31, the reception level thereof is below a predetermined level. Therefore, even if the signal from the beacon antenna 33 leaks and is received by the vehicle 34 traveling on the road 31, the position is not erroneously detected.

[0043]

According to the present invention, the position detection signal is extracted from the received signal only when the level of the received signal is equal to or higher than a predetermined level.
Therefore, it is possible to prevent erroneous detection of a position based on a signal with a low reception level, and it is possible to accurately detect the position and the road direction. Further, even if the vehicle enters an area where the level of the received signal is high, the level of the received signal may drop below a certain level for a short time. In such a case, when the level of the received signal falls below a certain level even for a short time, if the processing up to that point is stopped and a new processing is performed from that point, the extraction of the position detection signal There is a high possibility that the phase determination will be incorrect. Therefore, in the present invention, since the level drop for a very short time is ignored, more accurate position detection and direction determination can be performed.

Further, according to the present invention, since the phase confirmation processing is performed when the position detection signals have the same phase continuously for a fixed time or longer, the phase confirmation can be stably performed and the detection accuracy is improved. is there. In addition, there is no fear that an incorrect position will be detected based on the position detection signal leaking from an elevated road or the like that intersects the road on which the vehicle is passing.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an outline of position detection and direction identification using a roadside beacon.

FIG. 2 is a block diagram showing a configuration of a vehicle-mounted position detection device according to an embodiment of the present invention.

FIG. 3 is a waveform chart showing a specific example of received data in this embodiment.

FIG. 4 is a flowchart showing an outline of a processing procedure for position and direction detection in this embodiment.

5 is a flowchart showing the position and direction detection processing control, which is a specific and detailed version of the flowchart of FIG.

FIG. 6 is a flowchart showing the position and direction detection processing control, which is a specific and detailed version of the flowchart of FIG.

7 is an illustrative view showing four counters necessary for performing the control of FIG.

FIG. 8 is a flowchart showing a control operation of the display according to the embodiment of the present invention.

FIG. 9 is a diagram for explaining another effect of the present invention.

[Explanation of symbols]

 20 position detection device 24 1 kHz detector 25 phase determination device 26 CD detector 27 CPU

Claims (3)

[Claims] 1. A vehicle-mounted position detecting device using a roadside beacon, wherein a signal modulated by a first modulation method is divided into two parts.
Signal is modulated by a second modulation method that is out of phase with each other.
Signal so that the first modulation component is in phase and
When radiated from the remote controller , receiving means for receiving the radiated signal, the first signal when the carrier level of the received signal received by the receiving means is equal to or higher than a predetermined level, and when the carrier signal level is lower than the predetermined level The level discrimination means for outputting the second signal and the received signal received by the receiving means are changed by the first modulation method.
Detects the modulated signal and references it based on the phase of this signal
A second modulation method is used to convert the received signal received by the means for generating the clock and the receiving means.
The modulated signal is detected and the phase of this signal is created.
Second modulation with respect to the reference clock compared to the quasi clock
Phase determining means for determining the phase of the modulated signal whether positive phase or reverse phase method, the level time meter is started by on-edge of the second signal supplied from the determination unit, the time in which the second signal is continuous in advance An off timer for deriving an off output when a predetermined off time is reached, whether the first signal is given from the level discrimination means,
Alternatively, in a state where the first signal is not given but the off output of the off timer is not present, the phase determining means that employs the phase determined by the phase determining means as the confirmed phase, and the phase determining means The phase is reversed to
In response to this, the vehicle's current position is
An in- vehicle position detecting device comprising: a position determining unit that determines that the position is the installation position of the vehicle. 2. A pre-SL phase determining means is a said phase discriminating means
The vehicle-mounted vehicle using the roadside beacon according to claim 1, characterized in that, when the determined phase is continuously output for a predetermined time , the phase is adopted as a fixed phase.
Position detection device. 3. After the phase determining means adopts the determined phase
In a characterized in that before said position determining means determines the position of the vehicle, based on the fact that there is OFF output of the off-timer, further comprising a cancellation means for canceling the adopted phase in the phase determination means Claim 1 or 2
An in-vehicle position detecting device using the described roadside beacon.