KR102346830B1 - Vehicle driving mode control system - Google Patents

Abstract

The present invention relates to a vehicle driving mode control system comprising: a high-frequency process unit which extracts and processes a high-frequency component of a vehicle wheel speed; a level determination unit which determines an off-road level of a road surface on which a vehicle drives by comparing an output signal of the high-frequency process unit with a predetermined off-road reference value; a slip ratio calculation unit which calculates a slip ratio of a vehicle wheel; a slip determination unit which determines a slip state of the road surface by comparing an output signal of the slip ratio calculation unit with a slip reference value; a road surface determination unit which determines whether the road is in an abnormal state by integrating results of the level determination unit and the slip determination unit; and a control unit which controls whether to operate 4WD according to a vehicle speed by integrating an input state of a driving mode switch of a driver and a road surface state determination result of the road surface determination unit. The vehicle driving mode control system allows the vehicle to determine the road surface state without adding an expensive sensor and to automatically select an appropriate driving mode, and therefore, fuel efficiency is improved, driving stability is reinforced, and durability of the vehicle is improved.

Description

Vehicle driving mode control system {VEHICLE DRIVING MODE CONTROL SYSTEM}

The present invention relates to a technology for controlling a driving mode of a vehicle according to a state of a road surface on which the vehicle is traveling.

Based on the vehicle of the same model, 2WD (2 Wheel Drive) vehicles have better fuel efficiency than 4WD (4 Wheel Drive) vehicles.

By allowing the vehicle to switch between 2WD and 4WD on its own or according to the driver's needs according to the driving conditions on the road, the vehicle's driving performance can be optimized to the road conditions while improving the vehicle's fuel economy.

As described above, in order to automatically switch the driving mode according to the driving condition of the road, an expensive sensor for detecting the road surface condition of the road is required.

In addition, the wrong driving mode selection by the driver may lower the fuel efficiency of the vehicle and cause an overload in the powertrain of the vehicle, thereby reducing the durability of the vehicle.

The matters described as the background technology of the present invention are only for enhancing the understanding of the background of the present invention, and should not be taken as acknowledging that they correspond to the prior art already known to those of ordinary skill in the art. will be

KR 1020150057742 A

The present invention makes it possible to determine the road surface condition of the road on which the vehicle is traveling without adding an expensive sensor to the vehicle, thereby automatically selecting a driving mode suitable for the driving situation of the vehicle, thereby providing an appropriate driving mode according to the road surface environment. By providing a vehicle driving mode control system that improves the fuel efficiency of the vehicle, strengthens driving stability, and prevents powertrain overload due to the driver's misconfiguration of the driving mode, thereby improving the durability of the vehicle. There is a purpose.

A driving mode control system for a vehicle of the present invention for achieving the above object,

a high-frequency processing unit that extracts and processes high-frequency components of wheel speed;

a level determination unit that compares the output signal of the high frequency processing unit with a predetermined off-road reference value to determine an off-road level of the road on which the vehicle is traveling;

a slip ratio calculating unit for calculating a slip ratio of the wheel;

a slip determination unit which compares the output signal of the slip ratio calculation unit with a slip reference value to determine the slip state of the road surface;

a road surface determination unit synthesizing the results of the level determination unit and the slip determination unit to determine whether the road is in an abnormal state;

a controller for controlling whether 4WD is operated according to vehicle speed by synthesizing the driver's driving mode switch input state and the road surface state determination result of the road surface determination unit;

It is characterized in that it comprises a.

The high frequency processing unit

After taking the absolute value of the signal obtained by passing the wheel speed through the high-pass filter, the amount of change over time is calculated;

processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals;

processing the signal passing through the dead zone filter with a Signum function;

It may be configured to output the number of times of inversion per unit time of the signal passing through the Signum function as an output signal.

the off-road reference value used by the level determining unit includes a first reference value that is a frequency according to vehicle speed and a second reference value added to the first reference value;

when the output signal of the high frequency processing unit is equal to or greater than the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit determines the off-road level of the road surface as a first level;

When the output signal of the high frequency processing unit is equal to or greater than the sum of the first reference value and the second reference value, the off-road level of the road surface may be determined as the second level.

The slip ratio calculator calculates the slip ratio by dividing the difference between the wheel speed and the vehicle speed of the wheel by the vehicle speed. can be

When the road surface determination unit determines that the off-road level of the road surface determined by the level determination unit is equal to or higher than the first level, or the slip ratio calculation unit has an output signal of the slip ratio calculation unit greater than the slip reference value, and the road surface is in a slippery state, and may be configured to determine an abnormal state.

when the off-road level of the road determined by the level determination unit is equal to or greater than the first level, the average value of the off-road level during a first time window determined for a predetermined time is equal to or greater than a predetermined level average reference value;

During the second time window set for a predetermined time, when the ratio at which the slip determining unit determines that the road surface is in a slippery state is equal to or greater than a predetermined slip average reference value, it may be configured to determine that the road is in an abnormal state.

the control unit

When it is determined by the road surface determination unit that the road surface is in a normal state,

When the driver's driving mode switch input state is ON_ROAD, when the vehicle speed is equal to or greater than a predetermined first reference vehicle speed, the 4WD operation is stopped and the vehicle is controlled to drive in 2WD;

when the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed is greater than or equal to a predetermined second reference vehicle speed higher than the first reference vehicle speed, the 4WD operation is stopped and the vehicle is driven in 2WD;

When the road surface determination unit determines that the road surface is in an abnormal state,

when the driver's driving mode switch input state is ON_ROAD, when the vehicle speed is less than or equal to a predetermined third reference vehicle speed, control to drive in 4WD;

When the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed is less than or equal to a predetermined fourth reference vehicle speed higher than the third reference vehicle speed, it may be configured to control the vehicle to drive in 4WD.

On the other hand, the off-road level determination device of the present invention vehicle for achieving the above object,

After taking the absolute value of the signal obtained by passing the wheel speed through the high-pass filter, the amount of change over time is calculated; processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals; processing the signal passing through the dead zone filter with a Signum function; a high frequency processing unit configured to output as an output signal the number of inversions per unit time of the signal passing through the Signum function;

a level determination unit that compares the output signal of the high frequency processing unit with a predetermined off-road reference value to determine an off-road level of the road on which the vehicle is traveling;

It is characterized in that it comprises a.

the off-road reference value used by the level determining unit includes a first reference value that is a frequency according to vehicle speed and a second reference value added to the first reference value;

when the output signal of the high frequency processing unit is equal to or greater than the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit determines the off-road level of the road surface as a first level;

When the output signal of the high frequency processing unit is equal to or greater than the sum of the first reference value and the second reference value, the off-road level of the road surface may be determined as the second level.

The present invention makes it possible to determine the road surface condition of the road on which the vehicle is traveling without adding an expensive sensor to the vehicle, thereby automatically selecting a driving mode suitable for the driving situation of the vehicle, thereby providing an appropriate driving mode according to the road surface environment. It improves the fuel efficiency of the vehicle, enhances driving stability, and prevents the powertrain from overloading due to the driver's misconfiguration of the driving mode, thereby improving the durability of the vehicle.

1 is a configuration diagram of a vehicle driving mode control system according to the present invention;
2 is a view for explaining an example of determining a road condition according to the present invention;
FIG. 3 is a diagram specifically illustrating the operation of the control unit of FIG. 1 .

Specific structural or functional descriptions of the embodiments of the present invention disclosed in the present specification or application are only exemplified for the purpose of describing the embodiments according to the present invention, and the embodiments according to the present invention may be implemented in various forms. and should not be construed as being limited to the embodiments described in the present specification or application.

Since the embodiment according to the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiment according to the concept of the present invention with respect to a specific disclosed form, and should be understood to include all changes, equivalents or substitutes included in the spirit and scope of the present invention.

Terms such as first and/or second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one element from another element, for example, without departing from the scope of the present invention, a first element may be called a second element, and similarly The second component may also be referred to as the first component.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Other expressions describing the relationship between elements, such as "between" and "immediately between" or "neighboring to" and "directly adjacent to", etc., should be interpreted similarly.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that the described feature, number, step, operation, component, part, or a combination thereof exists, and includes one or more other features or numbers. , it should be understood that it does not preclude the existence or addition of steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as meanings consistent with the context of the related art, and unless explicitly defined in the present specification, they are not to be interpreted in an ideal or excessively formal meaning. .

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in each figure indicate like elements.

Referring to FIG. 1 , an embodiment of a driving mode control system for a vehicle according to the present invention includes: a high frequency processing unit 1 for extracting and processing high frequency components of wheel speed; a level determination unit (3) which compares the output signal of the high frequency processing unit (1) with a predetermined off-road reference value to determine an off-road level of the road on which the vehicle is traveling; a slip ratio calculating unit 5 for calculating the slip ratio of the wheel; a slip determination unit 7 which compares the output signal of the slip ratio calculation unit 5 with a slip reference value to determine the slip state of the road surface; a road surface determination unit 9 for synthesizing the results of the level determination unit 3 and the slip determination unit 7 to determine whether the road is in an abnormal state; The control unit 11 is configured to control whether 4WD is operated according to the vehicle speed by synthesizing the driver's driving mode switch input state and the road surface condition determination result of the road surface determination unit 9 .

That is, the present invention processes the wheel speed provided by the wheel speed sensor of the vehicle to determine the off-road level indicating the roughness of the road surface, and determines the slip state of the road surface from the slip ratio of the wheel, and the road surface determination unit ( In 9), it is determined whether the road can be viewed as a paved road state (on-road state) capable of normal high-speed driving by comprehensively considering the off-road level and the slip state of the road surface in 9) or whether it is not an abnormal state, and accordingly, the control unit By controlling whether 4WD is operated with (11), the road surface condition on which the vehicle is traveling is accurately determined without an additional expensive sensor, and the vehicle is controlled accordingly, thereby improving fuel efficiency and driving stability of the vehicle, and the driver's driving mode error This is to improve the durability of the vehicle by preventing the overload of the powertrain according to the setting.

For reference, here, the off-road refers to a road in which 4WD operation in which driving force is generated from all four driving wheels is more preferable than 2WD operation in order to properly secure the driving force of the vehicle, such as on an unpaved road, and the level The higher the value, the more severe the bumpiness of the road. On-road is a relative concept of off-road. As described above, it is a normal paved road, and 2WD operation is possible because high-speed driving of the vehicle is possible. This means a road that can focus on improving the fuel efficiency of vehicles.

The high-frequency processing unit 1 takes the absolute value of the signal obtained by passing the wheel speed through the high-pass filter, and then calculates the amount of change over time; processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals; processing the signal passing through the dead zone filter with a Signum function; It is configured to output the number of times of inversion per unit time of the signal passing through the Signum function as an output signal.

For example, a series of signals according to the passage of time obtained by passing the wheel speed signal measured by the wheel speed sensor through the high-pass filter are combined with ws(n-2), ws(n-1), ws(n)?? If equal to, the changes over time of the above signal ws_d1=[|ws(n-2)|-|ws(n-1)|], ws_d2=[|ws(n)|-|ws(n) -1)|]?? , and processing them with the dead zone filter to remove a signal below a predetermined level.

That is, the dead zone filter removes the signal when the amount of change is less than or equal to a predetermined value, and passes it only when it is larger than that, so that the influence of various noises can be excluded.

Therefore, it is preferable that the dead zone filter be designed by a number of experiments and analysis to a level that is suitable for noise removal according to the above purpose, while sufficiently remaining a signal necessary to determine the off-road level of the road surface. .

The signal passing through the dead zone filter is processed by the Signum function, wherein the Signum function is for x,

Therefore, when the signal passing through the dead zone filter is processed with the Signum function, it has one of 1, 0, -1, and in a series of time-dependent arrays of these values, the unit time is 1 second A value obtained by counting the number of times of inversion such as 1→-1 or -1→1 during the period is used as the output signal of the high frequency processing unit 1, and this signal can be viewed as a frequency.

The signal processing of the high frequency processing unit 1 as described above reduces memory usage and calculation data, so that it is possible to obtain the advantage of enabling frequency analysis in real time while using hardware of a relatively low specification.

On the other hand, the off-road reference value used by the level determining unit 3 is composed of a first reference value that is a frequency according to vehicle speed, and a second reference value added to the first reference value; When the output signal of the high frequency processing unit 1 is greater than or equal to the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit 3 determines the off-road level of the road surface as the first level do; If the output signal of the high frequency processing unit 1 is equal to or greater than the sum of the first reference value and the second reference value, the off-road level of the road surface is determined as the second level.

That is, the first reference value has a plurality of values determined in the form of a map according to the vehicle speed, and when the output signal of the high frequency processing unit 1 is greater than or equal to the first reference value determined according to the current vehicle speed, the road surface is basically in an off-road state. to be judged as

The second reference value is determined as a constant constant value or a value linked to vehicle speed, and is added to the first reference value to determine a more severe off-road condition.

Accordingly, the first reference value and the second reference value may be statistically determined by a plurality of driving tests and analysis for the corresponding vehicle at various vehicle speeds in accordance with the purpose as described above.

The slip ratio calculating unit 5 calculates the slip ratio by dividing the difference between the wheel speed and the vehicle speed of the wheel by the vehicle speed. is configured to yield.

For reference, the high frequency processing unit 1 and the level determining unit 3 may process both the wheel speeds of the driving wheels and the non-driven wheels, or process only the wheel speeds of the driving wheels, and the slip ratio calculation unit 5 and In the slip determination unit 7, it may be preferable to mainly calculate and process the slip ratio of the driving wheels.

The slip ratio is represented by the following formula,

In this case, the vehicle speed may be calculated using the average value of the vehicle speed calculated from the wheel speed of the driving wheels, or a vehicle speed calculated from the vehicle speed sensor signal of the output shaft of the transmission. It would be desirable

Here, when the vehicle speed is too low and 0 km/h is used, the calculation of the slip ratio becomes impossible. By setting the vehicle to be used at a low speed of 3 km/h, it is possible to always calculate the slip ratio.

The slip determination unit 7 determines the slip state of the road surface by comparing the output signal of the slip ratio calculation unit 5 with a predetermined slip reference value. It may be set at a level that can distinguish road surfaces such as icy roads, snowy roads, and sandy roads from paved roads that can transmit normal driving force.

The road surface determination unit 9 determines that the off-road level of the road surface determined by the level determination unit 3 is equal to or greater than the first level, or the slip ratio calculation unit 5 outputs the slip signal from the slip determination unit 7 . When it is determined that the road surface is in a slippery state because it is larger than the reference value, it is configured to determine that the road is in an abnormal state.

For example, the determination as shown in Table 1 below will be possible.

Off-road level ≥ 1 T T T T F F F F Left drive wheel slip ratio ≥ slip reference value F T F T F T F T Right drive wheel slip ratio ≥ slip reference value F F T T F F T T road abnormal condition T T T T F T T T

For reference, in Table 1, T (True) means that the condition of the corresponding item is satisfied or corresponds to that state, and F (False) has the opposite meaning. In the table above, the offload level is not 1 or more, Only when the slip ratios of the left and right driving wheels are both less than the slip reference value, the abnormal road condition is F, indicating that the road is in a normal on-road condition. When the offload level is equal to or greater than the first level, the average value of the offload level during the first time window determined by the predetermined time is equal to or greater than the predetermined level average reference value, and during the second time window determined by the predetermined time, the slip determination unit 7 ), when the ratio determined that the road surface is in a slippery state is equal to or greater than a predetermined sliding average reference value, it may be configured to determine that the road is in an abnormal state.

This is to reduce the possibility of erroneous determination due to noise. For example, when the first time window is set to 2 seconds, the road surface determination unit 9 continuously adjusts the off-road level determined from the current time to 2 seconds before. The average value is calculated and compared to the level average reference value.

For example, if the vehicle is actually driving off-road during the first time window, the off-road level determined a plurality of times during the first time window is generally determined to be 1 or more, and the average value thereof will be at least 0.8 or more, The level average reference value is set to, for example, 0.8 and compared thereto, thereby excluding the possibility of erroneous determination due to noise, and determining the off-road state of the road surface relatively accurately.

Accordingly, the first time window and the level average reference value are appropriate for removing noise and accurately and stably grasping the off-road condition of the road surface in accordance with the purpose as described above, and may be determined by a number of experiments and analysis.

The second time window and the sliding average reference value are also based on the same principle as described above, and similarly, it is a level that enables accurate and stable judgment while excluding noise on the slip condition of the road surface. can be appropriately determined.

In addition, the road surface determination unit 9 sets a predetermined third time window for the abnormal road condition, which is determined by combining the off-road condition and the slip condition, and sets the average value during that time as a predetermined comprehensive average reference value. In comparison, it may be possible to secure the accuracy and stability of judgment on the abnormal condition of the road.

For example, in the table, the state of T indicating the case where the road is in an abnormal state is replaced by 1, and F indicating the state in which the road is normal is replaced by 0, and during the third time window (eg, 3 seconds), the road If the average of the abnormal state of Therefore, if the overall average reference value is set to, for example, 0.7 and the average value for the road abnormal state determined during the third time window is compared, erroneous judgment due to noise is excluded as a whole, and a relatively stable and accurate judgment will be possible. .

For reference, FIG. 2 is a simplified description of an example of determining an abnormal state of a road when the left and right front wheels are the driving wheels according to the present invention as described above.

Referring to FIG. 3 , when the road surface determination unit 9 determines that the road surface is in a normal state, the controller 11 determines that the driver's driving mode switch input state is ON_ROAD, and the vehicle speed is higher than or equal to a predetermined first reference vehicle speed. When this occurs, it stops 4WD operation and controls to drive in 2WD; When the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed is greater than or equal to a predetermined second reference vehicle speed higher than the first reference vehicle speed, the 4WD operation is stopped and the vehicle is controlled to drive in 2WD.

Here, it is assumed that the driving mode switch selected by the driver can select ON_ROAD intended for normal high-speed driving on a paved road and OFF_ROAD intended for driving on an off-road or slippery abnormal road.

When the driver selects the driving mode switch to ON_ROAD in a state in which the road surface determination unit 9 determines that the road surface is in a normal state, when the vehicle speed is greater than or equal to the first reference vehicle speed (eg 30 km/h), the previous If 4WD was in operation, the 4WD operation is stopped and switched to 2WD operation, so that the vehicle's fuel economy can be improved.

Also, in a state in which the road surface determination unit 9 determines that the road surface is in a normal state, even when the driver selects the driving mode switch to OFF_ROAD, the vehicle speed is greater than or equal to the second reference vehicle speed (eg, 50 km/h) If the driver drives the vehicle at a vehicle speed of 50 km/h or higher, it can be determined that the road condition is an On-Road condition in which the vehicle can safely travel at high speed. , to stop the 4WD operation and switch to driving in the 2WD state, thereby contributing to the improvement of fuel efficiency of the vehicle.

In addition, when the road surface determination unit 9 determines that the road surface is in an abnormal state, the controller 11 determines that the driver's driving mode switch input state is ON_ROAD. control to drive; When the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed becomes less than or equal to a predetermined fourth reference vehicle speed higher than the third reference vehicle speed, it is configured to control the vehicle to drive in 4WD.

That is, if it is determined that the road surface is in an abnormal state and the driving mode switch is set to ON_ROAD, it is determined by the driver's mistake, and when the vehicle speed is less than or equal to the third reference vehicle speed (eg, 30 km/h), the control unit (11) is to switch to the 4WD operating state to enable stable driving of the vehicle.

In addition, if the driving mode switch is set to OFF_ROAD in a situation where it is determined that the road surface is abnormal, 4WD is operated in an area where the vehicle speed is less than or equal to the fourth reference vehicle speed (eg, 50 km/h). In an area exceeding the fourth reference vehicle speed, it is operated in 2WD.

This is because, when the driver drives the vehicle at a vehicle speed of 50 km/h or higher, the road condition can be determined as an on-road condition in which high-speed driving of the vehicle can be performed safely.

On the other hand, the apparatus for determining an off-road level of a vehicle according to the present invention calculates an amount of change over time after taking an absolute value of a signal obtained by passing a wheel speed through a high-pass filter; processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals; processing the signal passing through the dead zone filter with a Signum function; a high-frequency processing unit (1) configured to output as an output signal the number of times of inversion per unit time of the signal passing through the Signum function; The high frequency processing unit 1 may be configured to include a level determination unit 3 that compares the output signal with a predetermined off-road reference value to determine the off-road level of the road on which the vehicle is traveling.

In addition, the off-road reference value used by the level determining unit 3 includes a first reference value that is a frequency according to vehicle speed and a second reference value added to the first reference value; When the output signal of the high frequency processing unit 1 is greater than or equal to the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit 3 determines the off-road level of the road surface as the first level do; When the output signal of the high frequency processing unit 1 is equal to or greater than the sum of the first reference value and the second reference value, the off-road level of the road surface may be determined as the second level.

That is, it is possible to provide the off-road level determination device as described above and utilize it to determine the road condition in various braking systems or vehicle attitude control devices other than the driving mode control system of the vehicle of the present invention. .

Although the present invention has been shown and described with reference to specific embodiments, it is within the art that the present invention can be variously improved and changed without departing from the spirit of the present invention provided by the following claims. It will be obvious to those of ordinary skill in the art.

One; high frequency processing unit
3; level judging unit
5; slip ratio calculation unit
7; slip judgment part
9; road surface
11; control

Claims (9)

a high-frequency processing unit that extracts and processes high-frequency components of wheel speed;
a level determination unit that compares the output signal of the high frequency processing unit with a predetermined off-road reference value to determine an off-road level of the road on which the vehicle is traveling;
a slip ratio calculating unit for calculating a slip ratio of the wheel;
a slip determination unit which compares the output signal of the slip ratio calculation unit with a slip reference value to determine the slip state of the road surface;
a road surface determination unit synthesizing the results of the level determination unit and the slip determination unit to determine whether the road is in an abnormal state;
a controller for controlling whether 4WD is operated according to vehicle speed by synthesizing the driver's driving mode switch input state and the road surface state determination result of the road surface determination unit;
consists of,
The high frequency processing unit
After taking the absolute value of the signal obtained by passing the wheel speed through the high-pass filter, the amount of change over time is calculated;
processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals;
processing the signal passing through the dead zone filter with a Signum function;
configured to output the number of inversions per unit time of the signal passing through the Signum function as an output signal
A vehicle driving mode control system, characterized in that. delete The method according to claim 1,
the off-road reference value used by the level determining unit includes a first reference value that is a frequency according to vehicle speed and a second reference value added to the first reference value;
when the output signal of the high frequency processing unit is equal to or greater than the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit determines the off-road level of the road surface as a first level;
and when the output signal of the high frequency processing unit is equal to or greater than the sum of the first reference value and the second reference value, determining the off-road level of the road surface as a second level
A vehicle driving mode control system, characterized in that. 4. The method according to claim 3,
The slip ratio calculator calculates the slip ratio by dividing the difference between the wheel speed and the vehicle speed of the wheel by the vehicle speed. thing
A vehicle driving mode control system, characterized in that. 5. The method according to claim 4,
When the road surface determination unit determines that the off-road level of the road surface determined by the level determination unit is equal to or greater than the first level, or the slip determination unit determines that the road surface is slippery because the output signal of the slip ratio calculation unit is greater than the slip reference value, the road configured to be judged to be abnormal
A vehicle driving mode control system, characterized in that. 5. The method according to claim 4,
when the off-road level of the road determined by the level determining unit is equal to or greater than the first level, the average value of the off-road level during a first time window determined for a predetermined time is equal to or greater than a predetermined level average reference value;
and to determine that the road is in an abnormal state when the ratio determined by the slip determination unit that the road surface is slippery during the second time window set for a predetermined time is equal to or greater than a predetermined slip average reference value.
A vehicle driving mode control system, characterized in that. 7. The method of claim 5 or 6,
the control unit
When it is determined by the road surface determination unit that the road surface is in a normal state,
When the driver's driving mode switch input state is ON_ROAD, when the vehicle speed is equal to or greater than a predetermined first reference vehicle speed, the 4WD operation is stopped and the vehicle is controlled to drive in 2WD;
when the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed is greater than or equal to a predetermined second reference vehicle speed higher than the first reference vehicle speed, the 4WD operation is stopped and the vehicle is driven in 2WD;
When the road surface determination unit determines that the road surface is in an abnormal state,
when the driver's driving mode switch input state is ON_ROAD, when the vehicle speed is less than or equal to a predetermined third reference vehicle speed, control to drive in 4WD;
When the driver's driving mode switch input state is OFF_ROAD, when the vehicle speed is less than or equal to a predetermined fourth reference vehicle speed higher than the third reference vehicle speed, control to drive in 4WD
A vehicle driving mode control system, characterized in that. After taking the absolute value of the signal obtained by passing the wheel speed through the high-pass filter, the amount of change over time is calculated; processing the change amount signal with a dead zone filter configured to remove a signal of a predetermined level or less from among the change amount signals; processing the signal passing through the dead zone filter with a Signum function; a high frequency processing unit configured to output as an output signal the number of inversions per unit time of the signal passing through the Signum function;
a level determination unit that compares the output signal of the high frequency processing unit with a predetermined off-road reference value to determine an off-road level of the road on which the vehicle is traveling;
Off-road level determination device of the vehicle, characterized in that configured to include a. 9. The method of claim 8,
the off-road reference value used by the level determining unit includes a first reference value that is a frequency according to vehicle speed and a second reference value added to the first reference value;
when the output signal of the high frequency processing unit is equal to or greater than the first reference value and less than the sum of the first reference value and the second reference value, the level determining unit determines the off-road level of the road surface as a first level;
and when the output signal of the high frequency processing unit is equal to or greater than the sum of the first reference value and the second reference value, determining the off-road level of the road surface as a second level
Off-road level determination device of the vehicle, characterized in that.

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