JP2004175349A - Road surface condition determining method and device, and program for determining road surface condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road surface condition determining method for determining a condition of a traveling road surface even by a four-wheel drive vehicle. <P>SOLUTION: This road surface condition determining method is applied to determine a condition of the road surface where the four-wheel drive vehicle travels. The condition of the traveling road surface is determined on the basis of the relationship between a wheel speed rotation information of the driving wheel of the four-wheel drive vehicle during the traveling obtained from a wheel speed detecting means and the positional information calculated by receiving a GPS electric wave. The wheel speed rotation information is a rotating speed obtained by reading and calculating a period of wheel speed pulses and the number of pulses of the wheel speed detecting means at every specific time interval. The positional information is read in synchronization with the time interval of the speed detection on which the rotating speed is calculated, a vehicle moving distance is calculated on the basis of the positional information, a vehicle speed and an acceleration of the vehicle are calculated on the basis of the moving distance, then a slip ratio is operated on the basis of the rotating speed and the vehicle speed, and a condition of the traveling road surface is determined on the basis of the relationship between the slip ratio and an acceleration. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a method and a device for determining a road surface condition and a program for determining a road surface condition. More specifically, the present invention relates to a road surface state determination method and apparatus that can determine the road surface state during traveling, particularly in a four-wheel drive vehicle, and a road surface state determination program.

  Conventionally, before the braking force between the tire and the road surface exceeds the maximum value and the tire is locked, the brake torque acting on the wheel is reduced to prevent the wheel from being locked, and the maximum braking force is obtained. For example, an anti-lock brake device that controls the number of rotations of a driven wheel has been proposed. The antilock brake device calculates a relational expression between, for example, vehicle acceleration and a slip ratio, compares the slope of the relational expression with a preset threshold value, and obtains a road surface and a tire from the result of the comparison. (Refer to Patent Document 1).

Japanese Patent Application No. 2001-334920

  However, in the relationship between the vehicle acceleration and the slip ratio in the road surface friction coefficient determination method, the gradient of the μ-s curve between the road surface and the tire is obtained using the vehicle acceleration obtained from the rotation speed of the driven wheel, and the road surface Since the slipperiness is determined, there is a problem that the method cannot be applied to a four-wheel drive vehicle.

  The present invention has been made in view of the above circumstances, and provides a road surface state determination method and apparatus that can determine the state of a running road surface even in a four-wheel drive vehicle, and a program for road surface state determination. Aim.

  The road surface state determination method of the present invention is a road surface state determination method for determining a state of a road surface on which a four-wheeled vehicle is traveling, wherein a wheel speed of a driving wheel of a traveling four-wheeled vehicle obtained from wheel speed detection means. The state of the road surface during traveling is determined from the relationship between the rotation information and the position information calculated by receiving the GPS radio wave.

  Further, the road surface state determination device of the present invention is a road surface state determination device that determines a state of a road surface on which a four-wheel vehicle is traveling, and detects wheel speed rotation information of tires of driving wheels of the vehicle. Means, a GPS device that receives GPS radio waves and calculates position information, and a road surface state determination unit that determines the state of the road surface during traveling from the relationship between the wheel speed rotation information and the position information. I do.

  Further, the road surface condition determination program according to the present invention receives the wheel speed rotation information of the tires of the driving wheels of the vehicle obtained from the wheel speed detection means and the GPS radio wave to determine the road surface condition. It is characterized by functioning as road surface state determination means for determining a road surface state during traveling from a relationship with vehicle position information obtained from a GPS device that calculates information.

  Further, the road surface condition determination method according to the present invention is a road surface condition determination method for determining the state of a road surface on which a four-wheel vehicle is traveling, wherein the driving wheel wheels of the traveling four-wheel vehicle obtained from the wheel speed detection means are provided. It is characterized in that the state of the running road surface is determined from the relationship between the speed rotation information and the speed information of the vehicle calculated by receiving the GPS radio wave.

  Further, the road surface state determination device of the present invention is a road surface state determination device that determines a state of a road surface on which a four-wheel vehicle is traveling, and detects wheel speed rotation information of tires of driving wheels of the vehicle. Means, a GPS device that receives GPS radio waves and calculates vehicle speed information, and a road surface state determining unit that determines a state of a running road surface from a relationship between wheel speed rotation information and vehicle speed information. It is characterized by the following.

  Further, the program for determining the road surface condition of the present invention is based on the relationship between the wheel speed rotation information of the tires of the driving wheels of the vehicle obtained from the wheel speed detecting means and the speed information of the vehicle obtained from a GPS device that receives GPS radio waves. The present invention is characterized by functioning as road surface state determination means for determining a road surface state during traveling.

  ADVANTAGE OF THE INVENTION According to this invention, the state of the road surface at the time of driving | running | working in a four-wheel drive vehicle can be determined accurately. Further, the present invention can be applied to a two-wheel drive vehicle.

  Furthermore, since it can be easily linked to GPS position information, a road map with road surface conditions can be created.

  Hereinafter, a road surface state determination method and apparatus and a road surface state determination program according to the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, a road surface condition determination device according to one embodiment of the present invention is running on the basis of wheel speed rotation information of four tires FL, FR, RL, and RR provided in a four-wheeled vehicle. And a normal wheel speed detecting means 1 provided in association with each tire.

  The wheel speed detecting means 1 generates a rotation pulse by using an electromagnetic pickup or the like and measures the wheel speed rotation information from the number of pulses. An angular velocity sensor including one that measures wheel speed rotation information from a voltage can be used. The output of the wheel speed detecting means 1 is given to a control unit 2 which is a computer such as an ABS. The control unit 2 is connected to a GPS device 3 that receives GPS radio waves from a GPS antenna 3a and calculates position information of the position and speed of a running vehicle. Further, it is composed of a low μ road warning display 4 for informing the driver of the low μ road among the road surface conditions (high μ road, middle μ road, low μ road), for example, a liquid crystal display element, a plasma display element or a CRT. Display means is connected.

  As shown in FIG. 2, the control unit 2 stores an I / O interface 2a necessary for exchanging signals with an external device, a CPU 2b functioning as a center of arithmetic processing, and a control operation program of the CPU 2b. It comprises a ROM 2c and a RAM 2d from which data and the like are temporarily written when the CPU 2b performs a control operation, and from which the written data and the like are read.

The wheel speed detecting means 1 outputs a pulse signal (hereinafter referred to as a wheel speed pulse) corresponding to the number of rotations of the tire. Further, the CPU 2b calculates the rotational angular velocity F _i of each tire at a predetermined sampling period ΔT (sec), for example, every ΔT = 1 second, based on the wheel speed pulse output from the wheel speed detecting means 1.

Here, since the tires are manufactured by including the variation (initial difference) within the standard, the effective rolling radius of each tire (the value obtained by dividing the distance traveled by one revolution by 2π) is equal to that of all the tires. Even at normal air pressures, they are not always the same. Therefore, the rotational angular velocities F _i of the respective tires vary. Therefore, the rotational angular velocity F1 _i corrected to cancel the variation due to the initial difference is calculated. In particular,
F1 ₁ = F ₁
F1 ₂ = mF ₂
F1 ₃ = F ₃
F1 ₄ = nF ₄
Is corrected. The correction factor m, n, for example the vehicle calculates the rotational angular velocity F _i under the condition that it is traveling straight, based on the rotational angular velocities F _i The _{calculated, m = F 1 / F 2} , n = Obtained as F ₃ / F ₄ . Then, the wheel speed rotational information, the period and number of pulses of the wheel speed pulses of the wheel speed detecting means 1 reads the predetermined time intervals, a rotational speed calculated based on the F1 _i, tires of the wheels Is calculated.

  2. Description of the Related Art Conventionally, as represented by car navigation, a side position using a global positioning system (GPS) is generally known for position measurement of a vehicle. Much research has been done on improving the position accuracy in the frequency band where civil use is allowed. Among them, the accuracy is improved by measuring the phase of the carrier wave of the information sent from each satellite. The technology is introduced in the Journal of the Institute of Electronics, Information and Communication Engineers (Vol. 82 No. 12).

  The present invention acquires vehicle information (position information, vehicle speed information, and the like) by GPS with high accuracy, and determines the state of the road surface on which the vehicle is traveling. Then, the slipperiness of the running road surface is detected based on the state of the road surface, and if the road is a low μ road, an alarm is issued to the driver.

  In the present embodiment, the vehicle includes the wheel speed detecting means 1, the GPS device 3, and a road surface state determining means for determining a state of a running road surface based on a relationship between a rotational speed and position information.

  As the GPS device 3, for example, VBOX (trade name) manufactured by RACELOGIC can be used. The VBOX employs a position specifying method called Kinetic GPS, which corrects using a phase difference between carrier waves of satellite radio waves, so that the position can be specified with high accuracy. When the GPS device can calculate the speed of the vehicle with high accuracy using the Doppler effect of the carrier wave, it is also possible to directly determine the road surface condition from the speed information of the vehicle.

  Hereinafter, in the present embodiment, an example in which a road surface state is determined from position information for a GPS device that cannot directly calculate a speed will be described.

  The GPS device 3 according to the present embodiment reads distance information in synchronization with a time interval of speed detection for calculating a rotation speed, and then calculates a distance traveled by the vehicle from the position information. And vehicle information calculation means for calculating the vehicle speed and the vehicle acceleration from the vehicle. Further, in the present embodiment, there is provided a slip rate calculating means for calculating a slip rate from the rotation speed and the vehicle speed, and the determining means uses a relationship between the slip rate and the acceleration calculated by the GPS device. Then, the state of the road surface during traveling is determined. Here, the relationship between the slip ratio and the acceleration is the same as the μ-s curve of a general tire and road surface, and the gradient changes depending on the high μ road, the medium μ road, and the low μ road.

  Further, it is preferable to include moving average processing means for performing a predetermined number of moving average processes on the rotational speed and the speed or acceleration of the vehicle read at regular time intervals.

  In addition, the program for determining the road surface condition according to the present embodiment controls the control unit 2 between the rotational speed of the tire of the driving wheel of the vehicle obtained from the wheel speed detecting means 1 and the position information of the vehicle obtained from the GPS device 3. Based on the relationship, it functions as road surface state determination means for determining the state of the road surface during traveling. Further, the control unit 2 reads the position information in synchronization with a time interval of speed detection for calculating the rotation speed, and then calculates the vehicle speed and the rotation speed calculated from the moving distance of the vehicle calculated from the position information. Thus, it is made to function as a slip rate calculating means for calculating the slip rate, and as a judging means for judging the state of the road surface during traveling using the relationship between the slip rate and the acceleration calculated by the GPS device. Further, it functions as moving average processing means for performing a predetermined number of moving average processes on the rotation speed and the speed or acceleration of the vehicle read at regular time intervals.

  Hereinafter, an example of the operation of the road surface condition determination device of the present embodiment will be described along procedures (1) to (6).

(1) The rotational speeds (V1 _n , V2 _n , V3 _n , V4 _n ) of the four-wheel tires of the vehicle are calculated.
For example, the wheel speed data at a certain point in time for each wheel tire of the vehicle obtained from a sensor such as an ABS sensor is defined as rotation speeds V1 _n , V2 _n , V3 _n and V4 _n .

(2) Then, the rotational speed T of the drive wheels of the vehicle is calculated. For example, in the case of a two-wheel drive vehicle, the average rotational speed of the drive wheels can be used, and in the case of a four-wheel drive vehicle, the average rotational speed of the four wheels can be used. Alternatively, the rotation speed may be one of the two or four drive wheels.

(3) from the position information of the vehicle during traveling is calculated by using the GPS device, after calculating the moving distance of the vehicle, obtaining the vehicle speed Vf _n. As described above, in the case of a GPS device that calculates the speed directly, the vehicle speed Vf _n can be input without calculating from the position information.

(4) from the vehicle speed Vf _n 1 preceding vehicle speed data from, when the vehicle speed Vf _n-1, determined by the equation of the acceleration Vaf _n Hatsugi of the vehicle (1).
Vaf _n = (Vf _n -Vf _n-1 ) / Δt / G (1)

Here, Δt is a time interval (sampling time) between the average vehicle speeds Vf _n and Vf _n−1 calculated from the vehicle speed data, which is synchronized with the sampling of the rotation speed, and G is a gravitational acceleration. The sampling time needs to be 0.1 second or less in order to reduce data variation and determine in a short time. More preferably, the time is 0.05 seconds or less.

(5) The slip ratio S of the running vehicle is defined by the following equation (2). Here, T is the rotation speed of the drive wheel, and V is the vehicle speed.
S = (T−V) / T (2)

(6) Next, the relationship between the slip ratio of the drive wheels of the vehicle and the acceleration of the vehicle is determined.

Here, in order to determine the slip rate and the acceleration,
(1) In order to eliminate the influence of disturbance due to unevenness of the road surface, a predetermined number of data obtained for each sampling time, for example, 50 data are subjected to a moving average process.
In order to reduce the variation in data without reducing the number of data, data is sampled every short sampling time, for example, every several tens of ms, and the data having large variation obtained in this sampling time is moving averaged. This moving average processing can be applied to the vehicle speed data of the rotation speed and the vehicle speed.
(2) Then, in order to obtain a linear relationship between the slip rate and the acceleration, linear approximation is performed by a least squares approximation method every predetermined number, for example, every 20 pieces, and this process is moved and calculated every sampling time.

  As a result, the gradient of the straight-line approximation obtained for each sampling time is a value corresponding to the slipperiness of the road surface.

  Next, the present invention will be described based on examples, but the present invention is not limited to only these examples.

  A four-wheel drive vehicle (displacement 2.0 L) was prepared as a vehicle. The size of the tire is 205 / 55R16. In addition, as a running condition of the vehicle, a road surface in which the road surface μ of ceramic tile, dolset pebble and wet concrete was changed in Okayama truck course of Sumitomo Rubber Industries, Ltd. was adopted. The GPS sensor mounted on the vehicle is VBOX PRO manufactured by RACELOGIC. The sampling frequency is 50 Hz.

  Next, the vehicle traveled on the various road surfaces for about 10 seconds. FIG. 3 shows the relationship between the slip ratio and the acceleration plotted using the road surface condition determination device that stores the road surface condition determination program according to the present embodiment. From FIG. 3, it can be seen that the gradient of the linear approximation equation differs for each road surface, and that the gradient increases as the μ road becomes lower.

  Therefore, by determining the state of the road surface while the vehicle is traveling, and using this information for the shift control information of the automatic transmission, the tire pressure drop detection device (DWS) and the road surface state determination system, the traveling performance and traveling safety are improved. Can be improved.

It is a block diagram showing one embodiment of a road surface condition judging device of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of the road surface state determination device in FIG. 1. It is a figure which shows the relationship between the slip ratio and acceleration of the road surface run of a ceramic tile, a dollar set pebble, and wet concrete.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Wheel speed detection means 2 Control unit 3 GPS device 3a GPS antenna 4 Alarm display

Claims (18)

A road surface state determination method for determining the state of a road surface on which a four-wheeled vehicle is traveling, comprising: receiving wheel speed rotation information of driving wheels of a traveling four-wheeled vehicle obtained from wheel speed detection means; A road surface state determination method for determining a road surface state during traveling from a relationship with calculated position information. The wheel speed rotation information is a rotation speed calculated by reading the cycle and the number of wheel speed pulses of the wheel speed detection means at predetermined time intervals, and the rotation speed is calculated in synchronization with a time interval of speed detection for calculating the rotation speed. Then, the position information is read, a travel distance of the vehicle is calculated from the position information, a vehicle speed and an acceleration of the vehicle are calculated from the travel distance, and a slip ratio is calculated from the rotation speed and the vehicle speed. The road surface state determination method according to claim 1, wherein the road surface state during traveling is determined using the relationship between the slip ratio and the acceleration. The road surface state determination method according to claim 2, wherein a predetermined number of moving average processes are performed on the rotation speed and the speed or acceleration of the vehicle read at regular time intervals. A road surface condition determination device that determines the condition of a road surface on which a four-wheel vehicle is traveling, comprising: wheel speed detection means for detecting wheel speed rotation information of tires of driving wheels of the vehicle; And a road surface state determination unit that determines the state of the road surface during traveling from the relationship between the wheel speed rotation information and the position information. The wheel speed rotation information is a rotation speed calculated by reading a cycle and a pulse number of a wheel speed pulse of a wheel speed detection unit at predetermined time intervals, and is a rotation speed calculated by the GPS device. A distance calculating unit that reads the position information in synchronization with the time interval, and then calculates a moving distance of the vehicle from the position information; and a vehicle information calculating unit that calculates a vehicle speed and a vehicle acceleration from the moving distance. The road surface according to claim 4, further comprising: a slip ratio calculation unit that calculates a slip ratio from the rotation speed and the vehicle speed; and a determination unit that determines a state of the road surface during traveling by using a relationship between the slip ratio and the acceleration. State determination device. 6. The road surface state determination device according to claim 5, further comprising: moving average processing means for performing a predetermined number of moving average processes on the rotation speed and the vehicle speed or acceleration read at regular time intervals. In order to determine the state of the road surface, the computer determines the position of the vehicle obtained from the GPS device which receives the wheel speed rotation information of the driving wheels of the vehicle obtained from the wheel speed detecting means and the GPS radio wave and calculates the position information. A program for determining a road surface state that functions as road surface state determination means for determining a road surface state during traveling from a relationship with information. The wheel speed rotation information is a rotation speed calculated by reading the cycle and the number of wheel speed pulses of the wheel speed detection means at predetermined time intervals, and the rotation speed is calculated in synchronization with a time interval of speed detection for calculating the rotation speed. The slip information is read by the slip rate calculating means for calculating a slip rate from the vehicle speed calculated from the moving distance of the vehicle calculated from the position information and the rotational speed. 8. The program for determining a road surface state according to claim 7, wherein the program functions as determination means for determining the state of the road surface during traveling using the relationship with the calculated acceleration. 9. The program for determining a road surface state according to claim 8, wherein the program is operated as moving average processing means for performing a predetermined number of moving average processes on the rotational speed and the speed or acceleration of the vehicle read at regular time intervals. A road surface state determination method for determining the state of a road surface on which a four-wheeled vehicle is traveling, comprising: receiving wheel speed rotation information of driving wheels of a traveling four-wheeled vehicle obtained from wheel speed detection means; A road surface state determination method for determining a road surface state during traveling from a relationship with calculated vehicle speed information. The wheel speed rotation information is a rotation speed calculated by reading the cycle and the number of wheel speed pulses of the wheel speed detection means at predetermined time intervals, and the rotation speed is calculated in synchronization with a time interval of speed detection for calculating the rotation speed. Then, the vehicle speed information is read, a vehicle speed and a vehicle acceleration of the vehicle are calculated from the vehicle speed information, and a slip ratio is calculated from the rotation speed and the vehicle speed. The road surface state determination method according to claim 10, wherein the road surface state during traveling is determined using the relationship. The road surface state determination method according to claim 11, wherein a predetermined number of moving average processes are performed on the rotation speed and the speed or acceleration of the vehicle read at regular time intervals. A road surface state determination device that determines a state of a road surface on which a four-wheeled vehicle is traveling, a wheel speed detection unit that detects wheel speed rotation information of tires of driving wheels of the vehicle, a GPS radio wave, A road surface condition determination device comprising: a GPS device that calculates speed information; and a road condition determination unit that determines a condition of a road surface during traveling from a relationship between wheel speed rotation information and vehicle speed information. The wheel speed rotation information is a rotation speed calculated by reading a cycle and a pulse number of a wheel speed pulse of a wheel speed detection unit at predetermined time intervals, and is a rotation speed calculated by the GPS device. A vehicle information calculating means for reading the speed information of the vehicle in synchronization with the time interval, and calculating a vehicle speed and a vehicle acceleration from the speed information of the vehicle; and a slip ratio based on the rotational speed and the vehicle speed. 14. The road surface state determination device according to claim 13, further comprising: a slip ratio calculation unit that calculates the road surface state; and a determination unit that determines a road surface state during traveling using the relationship between the slip ratio and the acceleration. The road surface state determination device according to claim 14, further comprising a moving average processing unit that performs a predetermined number of moving average processes on the rotation speed and the speed or acceleration of the vehicle read at regular time intervals. In order to determine the state of the road surface, the computer, from the relationship between the wheel speed rotation information of the tire of the driving wheel of the vehicle obtained from the wheel speed detection means and the vehicle speed information obtained from the GPS device that receives the GPS radio wave, A road surface state determination program that functions as road surface state determination means that determines the state of the road surface during traveling. The wheel speed rotation information is a rotation speed calculated by reading the cycle and the number of wheel speed pulses of the wheel speed detection means at predetermined time intervals, and the rotation speed is calculated in synchronization with a time interval of speed detection for calculating the rotation speed. Means for reading the speed information of the vehicle, and then calculating a slip ratio from the vehicle speed and the rotational speed calculated from the speed information of the vehicle, a slip ratio and an acceleration calculated by the GPS device. 17. The program for determining a road surface condition according to claim 16, wherein the program functions as a determination unit that determines the state of the road surface during traveling using the relationship with 18. The program for determining a road surface condition according to claim 17, wherein the program functions as moving average processing means for performing a predetermined number of moving average processes on the rotational speed and the speed or acceleration of the vehicle read at regular time intervals.

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