JP2005138839A - Road surface determining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily determine a road surface state without requiringa high cost on road side facilities. <P>SOLUTION: A reference value circuit 86 matches the road surface states from a vehicle state detecting circuit 81 with estimated values from a road surface state estimating circuit 85. For example, a measured road surface μ is matched with a μ gradient as an estimated value to output a reference value (μ, μ gradient). A reference value changing circuit 87 compares the reference value obtained by the reference value circuit 86 with a conventional reference value stored in a memory. In a case where they have difference, the conventional reference value is corrected, and result of this correction is supplied to the road surface determining circuit 88. The road surface determining circuit 88 matches the estimated value for μ gradient obtained by the road surface state estimating circuit 85 with the reference value (μ, μ gradient) from the reference value changing circuit 87. The road surface μ on which the vehicle is currently driving is thus determined. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a road surface determination device, and more particularly to a road surface determination device suitable for use in vehicle travel control.

  Tire parameters relating to vehicle tires are estimated, and vehicle travel is controlled using the tire parameters. Examples of the tire parameter include a tire wear amount and a tire temperature.

  For example, Patent Document 1 discloses a tire abnormal wear detection device for estimating the amount of tire wear. This abnormal tire wear detection device determines abnormal tire wear from the change in the number of rotations of the tire when the dynamic radius of the tire decreases due to tire wear. Specifically, taking into account the change in dynamic radius due to tire air pressure, the correlation between the resonance frequency (depending on the air pressure) obtained from the wheel speed sensor and the tire rotation speed is obtained as a map. It is determined that the tire is worn when a rotational speed that deviates is detected.

  However, this tire abnormal wear detection device has a problem that the tire wear can be detected only when the tire is uniformly worn and the dynamic radius is uniformly reduced. For example, although the tire grip force decreases due to wear of the tire shoulder portion, such wear cannot be detected.

For example, Patent Document 2 discloses a device for providing a temperature sensor inside a tire housing and transmitting a temperature measurement value obtained by the temperature sensor to the inside or outside of the vehicle. However, this apparatus requires dedicated parts such as a slip ring and a temperature sensor for measuring the temperature of the tire, which increases the cost and has problems in terms of durability and reliability.
JP-A-5-332762 Japanese National Patent Publication No. 11-504585

  On the other hand, tire parameters that are affected by the external environment such as road surface friction are affected by the characteristics of both the vehicle side and road environment side, and it is difficult to strictly distinguish between the environmental side and the vehicle side. Therefore, it is difficult to estimate only by vehicle behavior and state quantity.

  In general, it is difficult to determine the road surface condition unless the tire is brought to some extent near the limit region (maximum friction region). However, if such control is performed, a change in vehicle behavior occurs, and vibrations and sounds are generated, leading to deterioration in ride comfort and operability.

  The road surface condition can also be realized by directly measuring the road side. However, there is a problem in that installing sensors on the entire road is costly. It is also possible to present it partially, but the friction characteristics vary greatly depending on the location, so there is not much point in performing it partially.

  An object of this invention is to provide the road surface determination apparatus which can determine a road surface state easily, without costing the installation on the road side.

  The invention according to claim 1 estimates the road surface friction state of the road surface on which the vehicle is traveling, based on the vehicle state detection means for detecting the traveling state of the vehicle and the traveling state of the vehicle detected by the vehicle state detection means. Road surface friction state estimating means, road condition measuring means for measuring the road surface condition of the road surface on which the vehicle is traveling, based on the vehicle running state detected by the vehicle state detecting means and the control state of the vehicle, When the road surface state newly measured by the road surface state measuring unit is the same as the road surface state of the reference value when the road surface friction state and the road surface state are associated with each other as a reference value, A reference value changing means for changing the road surface friction state to the road surface friction state estimated by the road surface friction state estimating means; a road surface friction state newly estimated by the road surface state estimating means; and a reference value after passing through the reference value changing means. Base There are, to solve the problems described above by comprising: a road surface condition judging means for judging road surface condition of a road surface on which the current vehicle running, the.

  According to the first aspect of the present invention, the road surface friction state of the road surface on which the vehicle is traveling is estimated based on the traveling state of the vehicle detected by the vehicle state detecting means. Further, the road surface state of the road surface on which the vehicle is traveling is measured based on the traveling state of the vehicle detected by the vehicle state detecting means and the control state of the vehicle. The road surface friction state and the road surface state obtained in this way are associated with each other and set as a reference value. When the vehicle travels again on the same road surface as the reference road surface, the reference surface road friction state is changed to the road surface friction state estimated by the road surface friction state estimation means. Thereby, a reference value is changed corresponding to a vehicle, a road surface state, etc. Then, based on the road surface friction state newly estimated by the road surface state estimation means and the reference value passed through the reference value changing means, the road surface state of the road surface on which the vehicle is currently traveling is determined.

  Further, as described in claim 2, the standardization means may associate the road surface friction state with the road surface state when the vehicle is in a predetermined traveling state.

  Further, as described in claim 3, the standardization means may associate the road surface friction state with the road surface state when the vehicle is traveling on a predetermined road surface.

  According to a fourth aspect of the present invention, there is provided a vehicle state detecting means for detecting a vehicle traveling state, a receiving means for receiving road surface environment information relating to a reference road surface, and a vehicle traveling state detected by the vehicle state detecting means. A road surface state estimating unit that estimates a road surface state of a traveling road surface, and each time the receiving unit receives the road surface environment information, the road surface state estimated by the road surface state estimating unit is stored as a reference value for a reference road surface. Based on the road surface state estimated by the road surface state estimation unit and the reference value for the reference road surface stored in the storage unit when the storage unit and the reception unit have not received the road surface environment information, The above-described problem is solved by including a determination unit that determines a state related to a road surface other than the reference road surface.

  According to the fourth aspect of the present invention, the road surface state of the road surface on which the vehicle is traveling is estimated based on the vehicle traveling state detected by the vehicle state detecting means. Each time the receiving unit receives the road surface environment information, the road surface state estimated by the road surface state estimating unit is stored in the storage unit as a reference value for the reference road surface. That is, the road surface state when traveling on the reference road surface is stored as a reference value. As a result, the reference value for the reference road surface is updated to an optimum value in accordance with changes in the road environment. Then, based on the road surface state estimated by the road surface state estimation unit and the reference value for the reference road surface stored in the storage unit, the state related to the road surface other than the reference road surface is determined.

  The storage means may store the road surface state estimated by the road surface state estimation means as a reference value for a reference road surface when the vehicle is in a predetermined traveling state.

  When the road surface state newly measured by the road surface state measurement unit is the same as the reference road surface state, the road surface determination device according to the present invention converts the road surface friction state of the reference value into the road surface friction state estimated by the road surface friction state estimation unit. The change in the vehicle characteristics is determined by determining the road surface state of the road surface on which the vehicle is currently traveling based on the road surface friction state newly estimated by the road surface state estimation means and the reference value after the reference value has been changed. The road surface condition can always be determined with high accuracy by changing the reference value in consideration.

  The road surface determination device according to the present invention stores the road surface state estimated by the road surface state estimation unit in the storage unit as a reference value for the reference road surface every time the reception unit receives the road surface environment information, and the road surface state estimation unit newly By determining the state relating to the road surface other than the reference road surface based on the estimated road surface state and the reference value with respect to the reference road surface stored in the storage means, not only the vehicle state but also road environment information from outside the vehicle is used. The road surface condition can be accurately determined.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention relates to vehicle travel control of VSC (Vehicle Stability Control), ABS (Antilock Braking System), TRC (TRaction Control System), AT (Automatic Transmission), ACC (Adaptive Cruise Control), ITS (Intelligent Transport System), etc. Therefore, it is suitable for use.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a road surface determination device 80 according to the first embodiment of the present invention. The road surface determination device 80 is installed in a vehicle and determines the road surface when the vehicle travels.

  The road surface determination device 80 includes a vehicle state detection circuit 81 that detects a traveling state of the vehicle, a drive circuit 82 that drives the road surface measurement device 90, and a control circuit 83 that controls the vehicle control device 91. The vehicle control device 91 controls the traveling of the vehicle, and the road surface measuring device 90 measures the road surface when the vehicle travels.

  The vehicle state detection circuit 81 determines, for example, how the vehicle has started, based on the wheel speed, whether the vehicle has started traveling, whether the vehicle is traveling straight, whether the vehicle is traveling at a constant speed, or whether the tire has been replaced. Detect whether it is in a bad state.

  The drive circuit 82 measures the timing for road surface measurement, and supplies a drive instruction signal for instructing driving of the vehicle control device 91 to the control circuit 83 at that timing. The drive circuit 82 determines that the road surface condition is poor based on the wheel speed fluctuation or vertical acceleration detected by the vehicle state detection circuit 81 (for example, if the road surface is significantly different between the left and right wheels, When it is determined that the vehicle is steered rapidly, the drive instruction signal may not be output. Thereby, road surface measurement can be performed only when the vehicle is traveling stably.

  Upon receiving this signal, the control circuit 83 controls the vehicle control device 91 so as to perform, for example, brake braking or throttle control of the accelerator. At this time, the control circuit 83 controls the vehicle control device 91 so that the control time is shortened and the control amount is also reduced so that the vehicle state does not change. Further, the control circuit 83 may suppress the fluctuation in the behavior of the vehicle by applying braking or the like to one or more wheels and simultaneously performing driving or steering so as to cancel the influence of the braking on the vehicle behavior. . Further, the control circuit 83 may perform drive control of the brake or the like in synchronization with the drive of the wiper, the air conditioner, the audio, etc., in order to eliminate the sound generated during the drive control. Further, the control circuit 83 may perform drive control such as a brake when the vehicle rides on a protrusion on the road surface in order to suppress vibration during drive control. Thereby, the fluctuation amount of the vehicle at the time of road surface determination can be decreased, and it can suppress that riding comfort deteriorates.

  The drive circuit 82 supplies the drive instruction signal to the control circuit 83 as described above, and drives the road surface measurement device 90 so as to start the road surface measurement. Thereby, the road surface measuring device 90 measures the road surface when predetermined control is performed on the vehicle.

Further, the road surface determination device 80 requires a road surface state measurement circuit 84 for obtaining a road surface state measurement result, a road surface state estimation circuit 85 for calculating an estimated value of the road surface state, a standardization circuit 86 for obtaining a reference value, and the like. A reference value changing circuit 87 that changes the reference value according to the road surface, and a road surface determining circuit 88 that determines the road surface state based on the reference value and the estimated value. When recognizing that control for determining the state is being performed, the road surface friction state is measured based on the vehicle state detected by the vehicle state detection circuit 81 at this time. The road surface state measurement circuit 84 obtains the road surface friction coefficient μ based on the following formula, for example.

μ = {I · (dω / dt) + K · Pb} / m
Pb: brake pressure, dω / dt: wheel acceleration, m: wheel load I: wheel inertia, K: brake pad friction coefficient The road surface state estimation circuit 85 is based on the road surface state detected by the vehicle state detection circuit 81 and An index indicating a friction state between road surfaces is estimated, and the estimated value is supplied to a standardization circuit 86 and a road surface determination circuit 88. As an index indicating the friction state, for example, a μ gradient (a variation amount of μ with respect to speed variation) in a steady running state of the vehicle is estimated.

  The standardization circuit 86 associates the road surface state from the vehicle state detection circuit 81 with the estimated value from the road surface state estimation circuit 85, and supplies this relationship to the reference value changing circuit 87 as a reference value. For example, the standardization circuit 86 associates the measured road surface μ with the estimated μ gradient, and outputs (μ, μ gradient) as the reference value.

  The reference value changing circuit 87 includes a memory (not shown) that stores the reference value obtained by the standardizing circuit 86. The reference value changing circuit 87 compares the reference value obtained by the standardizing circuit 86 with the conventional reference value stored in the memory, and corrects the conventional reference value if there is a difference. The correction result is supplied to the road surface determination circuit 88. For example, it is assumed that there are conventional reference values (μ, μ gradient), and new reference values (μ, μ gradient) are obtained. If the μ gradient is different when the conventional reference value and the current reference value μ are the same, the μ gradient is replaced. In other words, the reference value changing circuit 87 changes the μ gradient only (μ, μ gradient) as a new reference value, stores this reference value in the memory, and supplies it to the road surface determination circuit 88.

  The road surface determination circuit 88 determines the road surface state when traveling on a road surface different from the road surface for which the reference value is obtained. Specifically, the road surface determination circuit 88 associates the estimated value of the μ gradient obtained by the road surface state estimation circuit 85 with the reference value (μ, μ gradient) from the reference value changing circuit 87, so that the current vehicle travels. The road surface μ that is running is determined.

  As described above, the road surface determination device 80 changes the reference value in consideration of changes in vehicle characteristics such as tire replacement, aging deterioration, and load capacity, and thus accurately estimates the friction state between the tire and the road surface. be able to. Further, since the road surface determination device 80 minimizes vehicle control at the time of road surface state measurement, it is possible to reduce the amount of vehicle behavior and prevent the ride quality from deteriorating. Further, when the vehicle is traveling on a road surface that can be regarded as the same as the reference road surface, the change in the characteristic of the vehicle can be accurately estimated by comparing the change in the estimated value.

(Second Embodiment)
FIG. 2 is a block diagram showing the configuration of the road surface determination device 100 according to the second embodiment of the present invention. The road surface determination device 100 receives information from the road environment transmission device 110 provided on the road in the reference section, obtains a reference value that is an index indicating the road surface state, corrects the reference value as necessary, When traveling in another section, the road surface condition is accurately determined using the reference value.

  Specifically, the road surface determination device 100 includes a reference road surface information reception circuit 101 that receives information from the road environment transmission device 110, a vehicle state / behavior amount detection circuit 102 that detects a traveling state and behavior of the vehicle, and the like. , An estimation condition determination circuit 103 that determines whether the conditions are optimal for standardizing the estimated value, and an estimation circuit 104 that calculates the estimated value.

  Further, the road surface determination apparatus 100 includes a comparison circuit 105 that compares the conventional estimated value and the new estimated value, a determination reference correction circuit 106 that corrects the reference value according to the result of the comparison circuit 105, and a corrected reference. A situation judgment reference storage circuit 107 for storing values and a situation judgment circuit 108 for judging road surface conditions from the reference values and estimated values are provided.

  On the other hand, the road environment transmitting device 110 transmits road environment information to a traveling vehicle, and stores the recognized road environment information in the road environment recognition / storage circuit 111 and the road environment recognition / storage circuit 111. And a reference road surface information transmission circuit 112 for transmitting the transmitted information.

  The road environment recognition / storage circuit 111 measures, for example, road environment information related to the road surface condition such as the start position and end position of the road reference section, the distance of the reference section, the road surface friction coefficient μ, the road surface inclination angle, and the rainfall. And recognize the result. Then, the reference road surface information transmission circuit 112 transmits the environment information stored in the road environment recognition / storage circuit 111 to each vehicle that is traveling.

  The reference road surface information receiving circuit 101 receives road environment information from the road environment transmitting device 110 and supplies the road environment information to the estimation condition determination circuit 103 and the comparison circuit 105. The reference road surface information receiving circuit 101 cannot receive road environment information unless the vehicle is traveling on the reference road surface. The vehicle state / behavior amount detection circuit 102 detects vehicle state / behavior information related to the vehicle state and behavior such as wheel speed, steering angle, and vehicle body acceleration, and supplies this information to the estimation condition determination circuit 103 and the estimation circuit 104.

  The estimation condition determination circuit 103 estimates the road surface state based on the road environment information supplied from the reference road surface information receiving circuit 101 and the vehicle state / behavior information supplied from the vehicle state / behavior amount detection circuit 102, Determine if it is in a state suitable for standardization. For example, in the case where the vehicle is running straight, the estimation condition determination circuit 103 does not perform standardization when it is detected that the vehicle state / behavior amount detection circuit 102 is steering. Also, when the reference road surface information receiving circuit 101 receives that the weather is bad, that there is a fallen object on the road, that the road has already been standardized on the same road surface, etc., the estimation condition judgment circuit 103 also receives the reference condition determination circuit 103. Do not change. The estimation condition judgment circuit 103 instructs the estimation circuit 104 to perform standardization, and stops standardization when standardization is not performed. Note that the estimation condition determination circuit 103 instructs the situation determination circuit 108 to determine a road surface other than the reference road surface without performing standardization.

  The estimation circuit 104 provides an index indicating the road surface friction state based on the vehicle state / behavior amount from the vehicle state / behavior amount detection circuit 102 when the estimation condition determination circuit 103 instructs to perform standardization. presume. For example, the μ gradient (variation amount of μ with respect to the speed fluctuation) in the steady running state is estimated from the fluctuation of the wheel speed.

  The comparison circuit 105 compares indexes indicating road surface conditions when traveling on a reference section road. Specifically, the comparison circuit 105 obtains an index indicating the road surface state based on the environmental information from the reference road surface information receiving circuit 101, compares this index with the estimated value obtained by the estimation circuit 104, and compares this comparison. The result is supplied to the criterion correction circuit 106. For example, the comparison circuit 105 outputs the difference between the “conventional μ gradient” with respect to the reference road surface μ and the “currently estimated μ gradient” with respect to the reference road surface μ.

  The determination criterion correction circuit 106 instructs the situation determination criterion storage circuit 107 to correct the road surface condition index with respect to the reference road surface state from the comparison result obtained by the comparison circuit 105. For example, the determination criterion correction circuit 106 instructs to correct the μ gradient corresponding to the reference road surface μ to the value estimated this time as necessary.

  The situation determination criterion storage circuit 107 stores, for example, (μ, μ gradient) as a reference value for performing situation determination. Note that μ is obtained from road environment information received by the reference road surface information receiving circuit 101, and the μ gradient is estimated by the estimation circuit 104. Then, when there is a correction instruction from the determination reference correction circuit 106, the situation determination reference storage circuit 107 corrects the estimated value in accordance with the instruction, and stores the corrected estimated value as a reference value. For example, when there is an instruction to correct the μ gradient, the situation determination reference storage circuit 107 changes the μ gradient of the reference value (μ, μ gradient) to the μ gradient newly estimated by the estimation circuit 104.

  The situation determination circuit 108 performs road surface determination when the vehicle is traveling on a road other than the reference section road surface. Specifically, the situation determination circuit 108 determines the road surface state based on the estimated value obtained by the estimation circuit 104 and the reference value stored in the situation determination reference storage circuit 107. For example, the road surface μ is estimated from the estimated value of the μ gradient other than the reference section road surface using (μ, μ gradient) in the reference road surface section, that is, the correspondence relationship between μ and μ gradient.

  As described above, the road surface determination device 100 changes the reference value in consideration of not only the state and behavior of the vehicle itself but also the road state from the road environment transmission device 110, so that it corresponds to the constantly changing road state. The road surface condition can be accurately determined.

  Further, if the road environment transmitting device 110 is installed only in the reference section that manages the road environment, the road surface determination apparatus 100 can determine the road surface state using the reference value obtained in the reference section in the other sections. it can. Thereby, since a road surface can be determined without installing the road environment transmitter 110 in all sections, it is possible to accurately estimate the road surface state while reducing the burden of capital investment on the road side.

  In this embodiment, the μ gradient is updated when there is a difference between the conventional μ gradient and the newly obtained μ gradient, but the reference road surface information receiving circuit 101 newly receives the road environment information. You may make it update micro gradient every time.

It is a block diagram which shows the structure of the road surface determination apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the road surface determination apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

80, 100 Road surface determination device 84 Road surface state measurement circuit 85 Road surface state estimation circuit 86 Standardization circuit 87 Reference value change circuit 88 Road surface determination circuit 101 Reference road surface information reception circuit 104 Estimation circuit 105 Comparison circuit 106 Judgment reference correction circuit 107 Situation determination standard Memory circuit 108 Situation determination circuit

Claims (5)

Vehicle state detection means for detecting the running state of the vehicle;
Road surface friction state estimating means for estimating the road surface friction state of the road surface on which the vehicle is traveling based on the vehicle traveling state detected by the vehicle state detecting means;
Road surface state measuring means for measuring the road surface state of the road surface on which the vehicle is traveling based on the vehicle traveling state detected by the vehicle state detecting unit and the control state of the vehicle;
A standardization unit that associates the road surface friction state with the road surface state to serve as a reference value;
When the road surface state newly measured by the road surface state measuring means is the same as the road surface state of the reference value, the reference value change for changing the road surface friction state of the reference value to the road surface friction state estimated by the road surface friction state estimating means Means,
A road surface state determination unit that determines a road surface state of a road surface on which the vehicle is currently traveling, based on a road surface friction state newly estimated by the road surface state estimation unit and a reference value that has passed through the reference value change unit;
A road surface judging device.   The road surface determination device according to claim 1, wherein the standardization means associates the road surface friction state with the road surface state when the vehicle is in a predetermined traveling state.   The road surface determination device according to claim 1 or 2, wherein the standardization means associates the road surface friction state with the road surface state when the vehicle is traveling on a predetermined road surface. Vehicle state detection means for detecting the vehicle running state;
Receiving means for receiving road surface environment information relating to the reference road surface;
Road surface state estimating means for estimating the road surface state of the road surface on which the vehicle is traveling based on the vehicle traveling state detected by the vehicle state detecting means;
A storage unit that stores the road surface state estimated by the road surface state estimation unit as a reference value for a reference road surface every time the reception unit receives the road surface environment information;
Based on the road surface state estimated by the road surface state estimating unit and the reference value for the reference road surface stored in the storage unit when the receiving unit has not received the road surface environment information, other than the reference road surface Determination means for determining a state relating to the road surface;
A road surface judging device.   5. The road surface judging device according to claim 4, wherein the storage means stores the road surface state estimated by the road surface state estimation means as a reference value for a reference road surface when the vehicle is in a predetermined traveling state.

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