JPS62212896A - Road side beacon system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a roadside beacon method, and more specifically, after inputting starting point information, at least vehicle speed data and direction data are inputted. The present invention relates to a novel roadside beacon system used for vehicle position calibration and data transmission in navigation systems designed to display current position.

<Prior art> Conventionally, a vehicle is equipped with a small computer and a display device, and road map data stored in a recording device such as a compact disk is read out and displayed on a display 'IAWl', and the vehicle speed is also read out. The vehicle speed data from the sensor and the direction data from the direction sensor are input to calculate the position of the vehicle at each point in time and determine the running direction. Based on these calculation results and judgment results, the display 2. Description of the Related Art In recent years, so-called navigation systems have been provided in which a display indicating a vehicle is added to a corresponding portion of a road map displayed on a device.

If such a navigation system is used, the current location and traveling direction of the vehicle can be easily identified visually, and the vehicle can be reliably reached the destination without getting lost.

However, in the navigation system with the above configuration, errors that the vehicle speed sensor and direction sensor inevitably have accumulate as the traveling distance increases, and when the traveling distance exceeds a predetermined distance (however, this predetermined distance (It is determined by the degree of error of the vehicle speed sensor and direction sensor in each vehicle, and fluctuations in the atmospheric conditions at the location of each sensor, etc., and is not necessarily a fixed distance.) The vehicle display position on the display device may be the actual vehicle position. This results in a situation in which the device deviates significantly from its normal state, becomes unable to perform its original function, and becomes lost.

In order to solve such problems, roadside antennas are installed in the road transportation network at predetermined distances shorter than the distance at which the cumulative error exceeds a predetermined value, and the roadside antennas transmit position data and road direction. A signal containing data is transmitted only to a relatively narrow range, and the antenna attached to the vehicle receives the signal and inputs it into a computer, which corrects the vehicle's position and driving direction based on the received signal. It has been proposed to adopt a so-called roadside beacon method.

If such a roadside beacon method is adopted, it is possible to display accurate position data and direction data while the accumulated error is always below a predetermined value, thereby demonstrating the original performance of the navigation system. In particular, by installing roadside antennas in locations where large errors are likely to occur in the direction sensor, such as near railroad tracks or at railroad crossings, errors caused by external factors can be effectively eliminated. It has the advantage that it can be calibrated.

<Problems to be Solved by the Invention> In the roadside beacon system with the above configuration, signals including position data and road direction data are constantly transmitted by a roadside antenna with fairly high directivity, and the vehicle Since the signal is received only when passing through the area covered by the transmitted signal, and the necessary calibration can be performed based on the received signal, it is possible to widen the area covered by the transmitted signal. In this case, there is a problem that the deviation of the signal reception position with respect to the roadside antenna becomes large, and a sufficient calibration effect cannot be achieved.

To explain in more detail, the basic function of the roadside beacon method is to provide signals containing position data and road direction data to vehicles equipped with a navigation system, but the following functions can also be added to the roadside beacon system. This is required for effective use of the beacon method. In other words, ■ Assist the smooth operation of vehicles by providing the navigation system with additional traffic information such as road congestion, construction, and other road usage conditions around the location where the roadside antenna is installed. , ■ Add detailed map information including residential locations and personal names around the locations where roadside antennas are installed.
To make it easier to reach the final destination, ■ To improve the road map displayed by the display device by adding route map information covering a fairly wide range, including the locations where roadside antennas are installed, and providing it to the navigation system. It is being considered that the system will be updated to provide additional services such as smooth operation to remote areas, and if such additional services are to be provided,
It is essential to expand the transmission band of signals transmitted from roadside antennas and to expand the area covered by the transmitted signals.

When the transmission area and the area covered by the transmitted signal are expanded as described above,
This causes a problem in that the deviation of the signal reception position from the installation position of the roadside antenna becomes large, and the original purpose of calibrating the vehicle position cannot be performed accurately due to the influence of the deviation.

<Object of the invention> This light was made in view of the above problems,
It is an object of the present invention to provide a roadside beacon system that can easily cope with the expansion of various invisibility capabilities of the roadside beacon system and that can calibrate the original vehicle position with high accuracy.

Means for Solving the Problems> In order to achieve the above object, the roadside beacon system of the present invention is installed in a vehicle and uses required data of the transmission signal from the roadside antenna as calibration data. A navigator device that receives, calibrates and displays vehicle position data includes a data acquisition means for receiving a transmission signal having a level higher than a relatively low level among the received signals; a suppression/expansion means for suppressing the signal and expanding the high-level signal; and a position determination means for taking in a transmission signal of a level equal to or higher than a predetermined level from among the output signals of the suppression/expansion means and outputting a position determination signal. , a position determination signal, and calibration means for calibrating at least the position data based on the captured data.

However, the suppression/expansion means may be composed of an exponential amplification circuit.

Further, it is preferable that the signal received by the vehicle-mounted antenna is supplied to the data acquisition means and the suppression/expansion means through the fading removal means.

Further, the relatively low level may be set to a level at which the transmitted signal can be received without being affected by noise or the like.

<Operation> With the roadside beacon system configured as described above, when at least 1° of position data is transmitted to a vehicle from the roadside antenna installed at a predetermined position on the road transportation network, the data is transmitted from the roadside antenna. Among the signals, those having a level higher than a relatively low level can be captured by the data capturing means. Furthermore, by supplying the above signal to a suppression/expansion means, an output suppressed in response to a low level input and an output expanded in response to a high level input are obtained. A position determination signal can be output by inputting the signal at the level of 1 to the position determination means.

Then, the calibration means calibrates at least the position data by inputting the data acquired by the data acquisition means and the device determination signal constituted by the position determination means, and the most important is the output from the vehicle speed sensor, direction sensor, etc. Navigation operations can be performed based on the signals.

Thereafter, by repeating the above calibration operation and navigation operation, smooth vehicle operation can be assisted.

Furthermore, even when the suppression/expansion means is composed of an exponential amplification circuit, the same effect as described above can be achieved.

Furthermore, when the signal received by the vehicle-mounted antenna is supplied to the data acquisition means and the suppression/expansion means through the fading removal means,
Even if a signal with an intensity distribution significantly different from the intensity distribution of the transmitted signal is received due to the influence of fading, the above-mentioned influence can be eliminated by the fading removal means, and it can be assumed that the influence of fading has not occurred. The same effect as above can be performed in an equivalent state.

Furthermore, if the relatively low level mentioned above is set to a level that captures the transmitted signal without being affected by noise etc., position data and road direction data to perform the original function can be used. In addition, signals can also be input to the vehicle's navigation system, including the data necessary to perform additional functions.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 8 is a diagram schematically showing an example of a road map displayed on a display device, in which arrow A indicates the current position of the vehicle and the direction of travel. Then, roadside antennas Pi, P2. ...Pn is displayed corresponding to the actual installation position (however, this roadside antenna pi, P2
□... There is no particular inconvenience even if pn is not displayed). Although not shown in the diagram, buildings and the like that serve as landmarks are displayed.

FIGS. 6 and 7 are schematic diagrams explaining the roadside beacon method.
A roadside antenna (2) that transmits a signal including position data, road direction data, etc. is placed close to the road, and the signal is transmitted to a predetermined position of a vehicle (3) traveling on the road (1). Car-mounted antenna for receiving (4)
is installed, and the received signal is supplied to a navigation device (not shown). The roadside antenna (21) is configured with a highly directional antenna so as to cover only a relatively narrow range (see area R in the figure). It consists of an antenna that has directivity only upward.

Therefore, the signal transmitted from the roadside antenna ('2J) is not only directly received by the vehicle antenna (4), but also reflected one or more times by buildings, road surfaces, and other vehicles (3) before being received. However, since the in-vehicle antenna (4) has directivity only upwards from the horizontal direction, the sensitivity to each of the reflected waves is low, and only direct reception components are received.

FIG. 1 is a block diagram showing an embodiment of the roadside beacon system of the present invention.

The signal received by the on-vehicle antenna (4) is transmitted to the amplifier (5).
), and is supplied to a suppression/expansion circuit (6), a second level determination circuit (8), and a gate circuit (9). The output signal from the suppression/expansion circuit (6) is supplied to the first level determination circuit (7).

Further, the gate circuit (9) is opened by the output signal from the second level determination circuit (8). Further, the signal passing through the gate circuit (9) is temporarily stored in the memory I, and then the required communication data is read out by a device (not shown) connected to the communication data terminal (12). On the other hand, data necessary for navigation, such as road direction data and map data, is taken into the navigator (11). The current position data is taken into the navigator (11) by outputting a position judgment signal (timing pulse signal) from the first level judgment circuit (force), and the current position is calibrated. .

The determination reference levels in both of the level determination circuits (force (8)) are set to levels L1 and 12, respectively.

The suppression/expansion circuit (6) has a conversion characteristic as shown in FIG. 3A, and for example, when an input signal having a waveform shown in FIG. 3B is supplied, As shown in C, a predetermined range centered around the peak portion rises steeply,
This generates an output signal whose residual range is gentle.

The operation of the roadside beacon system having the above configuration will be explained in detail with reference to FIGS. 2 and 3.

A vehicle (3) travels on a road (1) and connects to a roadside antenna (2).
When approaching and then moving away, since the signal reception level at the in-vehicle antenna (4) is at almost zero level, both the level determination circuits (71 (81) A low level signal is input, the gate circuit (9) is kept closed,
The state is maintained such that no data is transmitted to the memory co) (see range T1 in FIG. 2).

The signal reception level gradually increases as it approaches the roadside antenna (2), and the signal level input to the second level judgment circuit (8) reaches the judgment reference level L.
Perform the above operation until it becomes larger than 2 (
(See range T2 in Figure 2).

That is, while the above operation is being performed, no data is transmitted from the memory to the navigator (11), and the data is transmitted based on vehicle speed data and traveling direction data from a vehicle speed sensor and a direction sensor (not shown). Navigator (
11), the current position and driving direction of the vehicle can be calculated and determined, and the current position and driving direction of the vehicle can be displayed on a display device (not shown) together with a road map.

After that, the vehicle (3) further approaches the roadside antenna (21), the signal reception level by the on-vehicle antenna (4) increases, and the signal level supplied to the second level determination circuit (8) exceeds the reference level L2. The gate circuit (
9) is heard, the signal received by the on-vehicle antenna (4) is amplified by the amplifier (5) and stored in the memory (see range T3 in Figure 2) and sent to the communication data terminal (12). data transmission, navigator (11
) is loaded with the required data.

When the vehicle (3) travels further and reaches a position almost directly facing the roadside antenna (2), the signal reception level by the on-vehicle antenna (4) further increases, and the suppression/expansion circuit (6)
Since the signal level converted by and supplied to the first level determination circuit (71) exceeds the reference level L1, a device determination signal composed of the level determination circuit (71) is supplied to the navigator (11), and at that moment Then, the position data stored in the memory ω) is taken into the navigator (11) to calibrate the current position within the main body of the device.As a result, the position data, traveling direction data, etc. are calibrated. , the exact current location and direction of travel can be displayed on the display device.

After that, the vehicle speed data from the vehicle speed sensor and the direction sensor are calculated based on the calibrated position and driving direction.
Based on the traveling direction data, the position of the vehicle (3) at each point in time and the traveling direction can be displayed as arrow A on the display device together with the road map.

Note that although FIG. 2 shows changes in the received signal level when the vehicle (3) is running at a constant speed, when the speed of the vehicle (3) changes, the above ranges TI ,
There is no particular inconvenience as only T2 etc. change in width and narrowness.

The same applies to FIG.

FIG. 4 is a block diagram showing another embodiment. The difference from the above embodiment is that the output signal from the amplifier (5) is subjected to fading removal by a detection circuit (13) and a low-pass filter (14). Through the device, the suppression/expansion circuit (
6) and the second level determination circuit (8); the configuration of the other parts is the same.

However, this embodiment is preferably applied when the directivity of the on-vehicle antenna (4) is low, or when the directivity of the on-vehicle antenna (4) is in the horizontal direction or downward than the horizontal direction. There are several possible cases.

Therefore, the signal transmitted from the roadside antenna (21) is not only directly received by the vehicle antenna (4), but also reflected one or more times by buildings, road surfaces, and other vehicles (3) before being received. As shown in FIG. 5, each of the above signals is received as a summatively or differentially convolved signal, that is, as a signal affected by the fading phenomenon due to multipath. become.

However, the signal shown in FIG. 5 above is amplified by the amplifier (5) and after 1ζ is subjected to the detection action by the detection circuit (13), and the high frequency component is removed by the low-pass filter (14). Since a signal very similar to the signal shown in is generated, the same operation as in the above embodiment can be performed thereafter.

In addition to the above configuration, the fading removal device may be configured by a combination of a detection circuit and a smoothing circuit having a predetermined time constant to obtain a hull I/8s1 signal.

As is clear from the above explanation, in the above embodiment, necessary data is fetched from the point when the level exceeds a relatively low level at which data transmission can actually be performed, and is temporarily stored in the memory CO1. , the necessary data is imported into the navigator (11) in advance, and the roadside antenna (2)
By transmitting position data to the navigator (11) only when the vehicle is sufficiently close to the navigator (11), the current position and driving direction can be calibrated. It is possible to reliably import the data into the navigator (11) and perform various functions (for example, displaying road usage conditions, displaying congestion information, etc.).In addition, other necessary communication data can be transferred to the communication data terminal (11). 12).

The position of the vehicle (3) is detected using the roadside antenna (2).
Since the detection is performed only when the vehicle (3) is sufficiently close to the vehicle (3) and the received signal level approaches its peak value, the position detection accuracy of the vehicle (3) can be maintained at a high level. However, this detection
Since this is performed after achieving steepness near the peak value by applying suppression and expansion processing to the received signal, accurate detection is possible without setting the reference level L1 too high, making it possible to detect By setting the level to a fairly low level in consideration of variations in the effective utilization of the antenna (4), reliable detection is possible even when the peak value of the received signal decreases, and detection accuracy is also improved. can be prevented from decreasing significantly.

<Effects of the Invention> As described above, this invention lowers the threshold level when acquiring data from roadside antennas, so it is possible to easily cope with an increase in the amount of transmitted data. When performing this, the received signal is sharpened and compared with the M-level signal, so by setting the reference level relatively low, reliable position detection is possible even when the peak value of the received signal decreases. It is possible to maintain high position detection accuracy, and to increase the amount of transmitted data, which is a very unique effect.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of Komei's roadside beacon system, Figure 2 is a diagram showing the relationship between changes in the signal reception level by the on-vehicle antenna and the reference level, and Figure 3 is a diagram showing the suppression/expansion operation. 4 is a block diagram showing another embodiment, FIG. 5 is a diagram showing changes in the level of a received signal affected by the fading phenomenon, and FIG. 6 is a schematic diagram showing the roadside beacon system. 7 is a schematic front view, and FIG. 8 is a diagram schematically showing an example of a road map displayed on a display device.

Claims (1)

[Claims] 1. In a roadside beacon system in which various data including at least position data is transmitted to a vehicle from a roadside antenna installed at a predetermined position on a road transportation network, the navigator device that receives the transmission signal from the roadside antenna, calibrates and displays vehicle position data, and data acquisition means for capturing signals at a level higher than a relatively low level among the received signals; A suppression/expansion means receives the received signal and suppresses the low level signal and expands the high level signal;
A position determination means that captures a signal having a level higher than a predetermined level among the output signals of the expansion means and outputs a position determination signal; and a calibration means that calibrates at least the position data based on the position determination signal and the captured data. A roadside beacon system characterized by comprising: 2. The roadside beacon system according to claim 1, wherein the suppression/expansion means comprises an exponential amplification circuit. 3. The roadside beacon according to claim 1 or 2, wherein the signal received by the on-vehicle antenna is supplied to the data acquisition means and the suppression/expansion means through the fading removal means. method. 4. The roadside beacon system according to any one of claims 1 to 3, wherein the relatively low level is set to a level at which the transmitted signal can be captured without being affected by noise or the like.