JPH09114371A - Road surface freezing predictor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a highly accurate prediction without depending on a difficult optical monitoring by providing a freezing prediction means which predicts the presence or the absence of the freezing condition of the surface of the road, that is being planned to be traveled, from the tomographic information including the amount of sunshine received and the altitude. SOLUTION: A processor 11 reads the outputs of a sunshine amount sensor 14c and a temperature sensor 14d and detects the amount of the sunshine and the temperature of the day. The sensor 14c is provided with solar batteries placed outside the car such as on the roof of the car and a condenser and outputs the voltage proportional to the integrated value of the amount of sunshine from the dawn of the day till the present time. Then, the processor 11 predicts the presence or the absence of the freezing condition of the sunshined portion of the road surface based on the amount of the sunshine. If a freezing condition is predicted, a plotting processor 15a plots the display picture indicating a warning message. The processor 15a writes the display picture of the warning message in a bank B of a frame memory 15b and a display control section 15c displays the display picture of the bank B on a liquid crystal display panel 15d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface freezing predicting apparatus which can realize a warning to a driver about road surface freezing, which is a problem when driving in a mountainous area in winter, by using a navigation system. .

[0002]

2. Description of the Related Art Various driving support systems such as a navigation system and an alarm system have been developed in order to enhance the safety and comfort of driving a vehicle.

Generally, in this type of driving support system,
Since a fairly expensive device may be used to realize the original function, it is desired to improve performance per cost by using a part of the device to realize a new function. Particularly, the navigation system is provided with a map information reproducing device which is encoded and stored in a CD-ROM or the like, and how to use the map information for multiple purposes becomes a problem.

By the way, when traveling in a mountainous area in winter, a slip accident due to a frozen road surface is likely to occur. In order to prevent such a slip accident due to a frozen road surface, the condition of the road surface in front is monitored using an optical device such as a camera or an optical sensor, or it is simply detected that the outside air temperature has dropped to around zero degrees. Therefore, there is known a system that warns a driver of a fear of freezing of a road surface. In addition, a traction control system (TCS) that prevents slipping on icy roads and wet roads
Is being developed.

[0005]

Among the conventional systems for warning a frozen road surface, those which predict the freezing of the road surface by monitoring the condition of the front road surface with an optical device such as a camera are described below.
It is difficult to improve the prediction accuracy. That is, in order to give the driver a warning with a time margin for deceleration operation, it is necessary to monitor the road surface considerably ahead in consideration of the normal vehicle speed.

As a result, the road surface to be monitored and the optical axis of the optical device are substantially parallel to each other, and there is a problem that optical monitoring becomes extremely difficult. Also, in the system that issues a warning based on the outside temperature,
Since the warning is easily generated, the driver does not actually encounter the frozen road surface for a long period of time, and there is a problem that the warning feeling is weakened or the reliability of the system is lost. .

Further, even in a traction control system (TCS) which prevents slipping on a frozen road surface or a wet road surface, the friction coefficient between the frozen road surface and the wet road surface is significantly different from that of the tire. Therefore, since the traction control system cannot identify in advance which road surface, there is a problem that the control effect cannot be improved.

[0008]

DISCLOSURE OF THE INVENTION A road surface freezing predicting device of the present invention is a freezing predicting means for predicting a risk of freezing of a road surface to be traveled on the basis of topographical information including the amount of solar radiation in the sun and altitude. It is provided with means for warning the driver of the danger of freezing of the road surface and notifying the traction control system.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to one embodiment of the present invention, when predicting the risk of freezing of a road surface, information indicating that the traction control system has operated is also used.

[0010]

FIG. 1 is a block diagram showing the configuration of a navigation system 10 including a road surface frost prediction device according to an embodiment of the present invention, together with a related traction control system (TCS) 20 and an engine control unit (ECU) 30. It is a figure. That is, this navigation system includes a processor 11, a map information reproducing unit 12, and a GPS receiver 1.
3, a sensor group 14, a screen display unit 15, a speaker 16 and a key input unit 17.

The processor 11 detects the position of the vehicle on the basis of the information received from the GPS receiver 13, instructs the map information reproducing section 12 to reproduce the road map in a predetermined range including the position of the vehicle, and reproduces it. When the generated map information is received from the reproduction unit 12, the drawing processor 1 of the screen display unit 15 receives the map information.
5a and instruct drawing. When detecting the position of the host vehicle, the processor 11 calculates the traveling distance obtained by integrating the vehicle speed pulse supplied from the vehicle speed sensor 14a, the vehicle direction obtained from the direction sensor 14b including a gyro, and the like. It is used as auxiliary information when the GPS receiver 13 cannot be used in a tunnel or the like.

The processor 11 preliminarily calculates the optimum planned traveling route based on the target point input by the driver from the key input unit 17, and draws the planned traveling route with a thick line or different coloring to change the position of the vehicle. The drawing processor 15a is instructed accordingly. In the display control unit 15, the drawing processor 15a draws a road map and displays it in the frame memory 1
At the same time as writing to bank A of 5b, the current position of the vehicle, the planned traveling route, etc. notified from the processor are written in the road map of bank A.

The display control unit 15c reads the screen information written in the bank A at a constant cycle and transfers the screen information to the liquid crystal display panel 15d to display a road map including the current position of the vehicle and a planned traveling route on the liquid crystal display panel. 15d is displayed. In parallel with the control related to the screen display of the road map and the like, the processor 11 displays guidance information regarding the course change such as left turn and right turn at the intersection on the liquid crystal display panel 15d and outputs a voice message from the speaker 16. Or

The processor 11 executes processing for predicting road surface freezing as described below in parallel with various typical processing relating to the navigation. That is, the processor 11 first detects the solar radiation amount and the temperature on this day by reading the outputs of the solar radiation sensor 14c and the air temperature sensor 14d. The solar radiation sensor 14a is composed of a solar battery and a battery installed at an appropriate location outside the vehicle, such as the roof of the vehicle, and outputs a voltage proportional to the integral value of the solar radiation from the sunrise of the day to the present time. The processor 11 predicts the presence / absence of freezing in the sunlit portion on the road surface based on the amount of solar radiation.

The thickness of ice on the road surface is 1 mm and the minimum temperature is -3.
^{Estimate as} C. The melting heat of ice is 80 cal / gr, the specific heat is 2 cal / gr
・^O C, specific gravity is about 1.0, so 1 mm ² in 1 cm ² area
At a temperature of -3 ^o C and a weight of 0.1 gr ice at 0 ^o
The amount of heat required to make C water is about 10 cal. Also, a unit area made of asphalt or concrete
The amount of heat required to raise the temperature of the (1 cm ² ) road surface from −3 ^o C to 0 ^o C is about 15 cal, considering the amount of heat that escapes to the inside. Therefore, in this case, a total amount of heat of about 25 cal / cm ² is required to melt the ice on the road surface.

The processor 11 refers to the output value of the solar radiation amount sensor 14c, and calculates the integrated value of the amount of solar radiation from the sunrise by multiplying the required heat amount, 25 cal / cm ² in the above example, by a predetermined safety factor. For example, it is determined whether or not it exceeds 50 cal / cm ² . According to the science chronology of the Tokyo Observatory, 1
The national average of direct solar radiation for the month is about 0.86 KW / m ² ≈ 1.2 cal /
Since it is cm ² · min, if the road surface is in the sun for more than 40 minutes, the ice will melt and the freezing will disappear.

However, the above-mentioned direct solar radiation amount is the solar radiation amount in an ideal state in which it is incident on the road surface at a right angle in fine weather, and the actual solar radiation amount is due to the influence of cloudy weather, that the sun rays are obliquely incident on the road surface, Considering the reflection component, etc., the value becomes smaller than this direct solar radiation amount, and the time required for melting also becomes longer. Further, in predicting the freezing of the road surface, not only the amount of heat that escapes to the inside of the road surface by heat conduction, but also the amount of heat that is carried away into the air by the wind is considered. Therefore, if necessary, a sensor for detecting the wind speed, etc. is added,
Alternatively, these weather parameters are input by the driver from the key input unit 17.

The processor 11 predicts the freezing of the road surface not only in the shade but also in the sunny place if the integrated value of the amount of solar radiation from sunrise does not exceed the amount required to eliminate the freezing of the sunlit road surface. The drawing processor 15a is caused to draw a display screen for displaying an alarm message regarding the total freezing of the road surface. The drawing processor 15a creates a warning message display screen and writes it in the bank B of the frame memory 15b. The display control unit 15c intermittently displays the display screen of the bank B at a frequency low enough not to bother the driver, or at a frequency low enough to perform so-called subliminal display in which the driver can unknowingly transmit an alarm. And is displayed on the liquid crystal display panel 15d.

If the integrated value of the amount of solar radiation from sunrise exceeds the amount required to eliminate the freezing of the sunlit road surface, the processor 11 determines that there is a road surface in the shaded area where the alarm is to be issued. The detection process of is started. First, the processor 11
Instructs the map information reproducing unit 12 to reproduce the topographic map within a predetermined range including the planned traveling route ahead of the current position of the own vehicle. The topographic map information reproducing unit 12 reads out, from the CD-ROM, the topographic map information which is compressed and stored in the CD-ROM within the range designated by the processor 11, and decompresses and decodes the data. Go and transfer to processor 11.

This topographic map information is composed of contour maps as shown in FIG. 2 and information on roads and buildings such as bridges and tunnels attached to the roads.
The triangle displayed on the road in the upper right part of FIG. 2 is a symbol indicating the current position of the host vehicle. The processor 11
First, a topographic map is created from the contour lines included in the topographic map information and having an undulation as shown in FIG. Next, the processor 11 refers to the calendar held in the built-in memory to calculate the locus (zodiac) of the position of the sun from the current position to the combination of the elevation angle and the azimuth angle from the sunrise to the sunset.

Next, the processor 11 calculates the shaded portion generated in the planned traveling route from the created bird's-eye view topographic map and the trajectory of the sun, as illustrated in FIG. The shaded area changes with the passage of time, but only the shades that have occurred up to the present time, which are illustrated by dark black, are detected. The processor 11 predicts that there is a risk of freezing on the road surface in this shaded area, and as shown in FIG. 5, displays that area on the road map being displayed in a color different from the surroundings such as red. At the same time, the speaker 16 outputs a buzzer sound or a warning message.

Navigation system processor 1
1 notifies the traction control unit 21 of the prediction of the road surface freezing together with information on the approaching curve.
The traction control unit 21 includes slips of driving wheels and driven wheels output from the wheel sensors 22 and 23,
The known traction control is executed based on the steering angle output from the steered steering angle sensor 24, the vehicle speed output from the vehicle speed sensor 25, and the road surface freezing prediction and the curve notified from the processor 11 of the navigation system. Perform special control based on the notification.

That is, as illustrated in the flowchart of FIG. 6, the traction control unit 21 controls the rotational speeds of the drive wheels and the driven wheels under the condition that the road surface is not frozen by the navigation system 10 such as in summer. The engine control unit (ECU) detects the idling and skidding of the wheels based on the difference and the turning radius predicted from the steering angle and the turning radius predicted from the difference between the rotation speeds of the inner and outer wheels. By issuing a command to reduce the output, a known traction control for suppressing the idling or skidding of the wheels is executed (steps 51 and 52).

When the traction control unit 21 receives a road surface freeze notification from the processor 11 of the navigation system (step 51), it checks whether or not there is a notification regarding the curve (step 53). The distance and the radius of curvature of this curve are received (step 54). The traction control unit 21 calculates the vehicle speed at which the vehicle can safely pass through the curve of the frozen road surface from the friction coefficient of the frozen road surface and the tire and the radius of curvature of the curve (step 55), and then detects the vehicle speed (step 56).

If the detected vehicle speed exceeds the safe vehicle speed on the calculated curve, the traction control unit 21 supplies an output reduction signal to the engine control unit 30 to reduce the vehicle speed. To reduce this engine output,
Braking by automatic brake operation may be added.
If the icy road surface is a straight road without a curve, the traction control unit 21 sends an engine output reduction signal to the engine control unit 30 to execute acceleration suppression control (step 58).

The engine output reduction signal output from the traction control unit 21 to the engine control unit 30 is
The operation information indicating that the traction control unit 21 is operating is notified to the processor 11 of the navigation system. The processor 11 uses the operation information of the traction control unit as a learning material for evaluating whether or not the prediction of the road surface freezing performed immediately before is appropriate. That is, various estimated weather parameters such as ice thickness, wind speed, and temperature are corrected.

The configuration for detecting the integrated value of the amount of solar radiation from sunrise to the predicted time point by using the solar radiation sensor has been exemplified above. However, instead of detecting the actual value, the integrated value of the solar radiation amount from the sunrise may be estimated based on the current solar radiation amount.

Further, the structure in which the road map information and the topographic map including the contour lines are separately stored in different CD-ROMs has been exemplified, but these are stored as a single information in a single CD-RO.
The configuration may be stored in M.

Further, a configuration has been exemplified in which, when a predicted frozen road surface appears, an engine output reduction signal is output from the navigation system to the engine control unit via the traction control system. However, when the predicted frozen road surface appears, the engine output reduction signal may be transmitted to the engine control unit directly from the navigation system without using the traction control system.

[0030]

As described above in detail, the road surface freezing predicting apparatus of the present invention comprises a freezing predicting means for predicting whether or not the road surface to be traveled is frozen based on the terrain information including the amount of solar radiation in the sun and the altitude. Therefore, highly accurate prediction can be performed without resorting to difficult optical monitoring. Also,
Since it is possible to promptly notify the traction control system of the prediction of the appearance of a frozen road surface having a friction coefficient significantly different from that of a wet road surface, there is an advantage that effective traction control becomes possible.

Further, the road surface freezing prediction apparatus of the present invention has an advantage that the cost performance can be improved because most of the constituent elements can be shared with the existing navigation system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a navigation system including a road surface frost prediction device according to an embodiment of the present invention, together with a related traction control system and an engine control unit.

FIG. 2 is a conceptual diagram showing an example of topographic map information including contour lines reproduced by a map information reproducing section 12 of FIG.

3 is the processor 1 of FIG. 1 based on the topographic map information of FIG. 2;
It is a conceptual diagram which shows an example of the topographic map by the bird's-eye view created by 1.

FIG. 4 is a conceptual diagram exemplifying a shaded portion on a road surface to be traveled, which appears in the topographic map by the bird's-eye view of FIG. 3;

FIG. 5 is a conceptual diagram showing an example of a freezing prediction portion generated on a road surface on which a vehicle is scheduled to travel.

FIG. 6 is a flowchart for explaining the content of processing executed by the traction control unit 21 of FIG. 1 based on road surface freezing prediction.

[Explanation of symbols]

10 Navigation system including road surface freeze prediction device 11 Processor 12 Map information playback unit 13 GPS receiver 14c Solar radiation sensor 15 Screen display unit 20 Traction control system 21 Traction control unit 30 Engine control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // G01S 5/14 G01S 5/14

Claims (6)

[Claims] 1. Freezing predicting means for predicting a risk of freezing of a road surface to be traveled from the amount of solar radiation in the sun and topographical information including altitude, and notifying means for notifying a driver of the predicted fear of freezing of the road surface. And a road surface freezing prediction device. 2. Freezing predicting means for predicting a risk of freezing of a road surface to be traveled based on the amount of solar radiation in the sun and topographical information including altitude, and engine output before reaching a road surface where the risk of freezing is predicted. A road surface freezing prediction device comprising means for reducing the road surface. 3. Freezing prediction means for predicting the risk of freezing of a road surface to be traveled from the amount of solar radiation in the sun, topographical information including altitude, and operation information of the traction control system, and the risk of freezing is predicted. A road surface freezing prediction apparatus comprising: means for reducing an engine output before reaching a road surface. 4. The road surface freezing prediction device according to claim 2 or 3, wherein the notification means further includes means for notifying a driver of the predicted fear of freezing. 5. The method according to claim 1, wherein the means for notifying the driver of the predicted road surface freezing is provided with means for subliminally displaying a warning on the display screen of the navigation system. Road surface freeze prediction device. 6. The road surface freezing prediction apparatus according to claim 1, wherein the freezing prediction means forms part of a navigation system.