KR101977643B1 - Control method for 4wd system - Google Patents

Abstract

A method for controlling a 4WD system according to the present invention is a method for controlling a 4WD vehicle equipped with a twin clutch, the method comprising: a first step of receiving external information affecting the running of the vehicle; A third step of determining an occurrence of an abnormal mode in which the vehicle deviates from a predetermined normal trajectory when the vehicle travels in a curve section, and a third step of determining whether the vehicle is in a traveling mode determined in the third step And a fourth step of controlling the operation of the twin clutch according to the abnormal mode and distributing the driving force between the front wheel and the rear wheel of the automobile and the driving force between the rear wheel outer wheel and the rear wheel inner wheel of the automobile.

Description

4WD system control method {CONTROL METHOD FOR 4WD SYSTEM}

The present invention relates to a 4WD system control method, and more particularly, to a 4WD system control method equipped with a twin clutch.

In the case of a 4WD vehicle equipped with a twin clutch, a torque backing technology is applied to control the ratio of the torque transmitted to the front and rear wheels of the transmission at a certain ratio or the ratio of the driving force transmitted to the left and right wheels of the rear wheel .

The torque vectoring technique is based on the steering effort through the steering wheel manipulation or the acceleration will through the accelerator press, the longitudinal direction, lateral acceleration and yaw rate of the vehicle, road friction coefficient, tire condition, vehicle dynamics model, The tire force added to each wheel is calculated to determine the driving force distributed to each wheel. This can improve the handling and traction performance of the vehicle.

At this time, since the control unit measures the road surface friction coefficient through the time at which each wheel is slipped, a time delay occurs from the measurement to the control, and it is difficult to measure the road surface friction coefficient unless the wheel slips.

Therefore, when the control unit controls the torque transmitted to each wheel on the basis of the inaccurate road surface friction coefficient, unnecessary driving force or braking force may be generated and the stability of the vehicle may be weakened.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

KR 10-2010-0052874 (May 20, 2010)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a 4WD system control method capable of stable control even in emergency situations through feedforward control.

According to another aspect of the present invention, there is provided a control method for a 4WD vehicle equipped with a twin clutch, the method comprising: a first step of receiving external information that affects the driving of the vehicle; A second step of determining a driving mode using external information received in the first step, a third step of determining occurrence of an anomaly mode in which the vehicle deviates from a predetermined normal trajectory at the time of driving the curve section, A fourth clutch that controls the operation of the twin clutch according to the traveling mode and the abnormal mode determined in the third step and distributes the driving force between the front wheel and the rear wheel of the automobile and the driving force between the rear wheel outer wheel and the rear wheel inner wheel, .

The first step may include receiving at least one of road surface information, accident information, and weather information of the road and transmitting the information to the control unit of the automobile, and the second step may include using the information transmitted to the control unit in the first step Thereby determining the running mode.

The second step includes a first determining step of determining the risk of an accident using the information transmitted to the controller in the first step and selecting an emergency driving mode or a general driving mode; And a second determination step of determining whether or not the actual operation information of the automobile is identical.

The second determination process may include a twenty-first determination process performed when the general mode is determined in the first determination process and a twenty-second determination process performed when the mode is determined to be an emergency running mode in the first determination process , The 21st decision step performs the third step when the handling information of the automobile matches the operation information and performs the first decision step when it does not match, The control unit performs the twenty-first determination process when the handling information of the automobile matches the operation information, and performs the third step when the operation information does not coincide with the handling information of the automobile.

The third step is to compare the handling information of the automobile with the operation information to determine whether the automobile is in the state of oversteer, understeer, or counter-steer.

The third step may include a third determination step performed when the third step is entered in the twenty first determination step and a fourth determination step performed when the third step is entered in the twenty second determination step Wherein the fourth step is performed when the vehicle is in an oversteer state in the third determining step and a twelfth control step performed when the vehicle is in an understeer state in the third determining step, And a thirteenth control process performed when the vehicle is in the counter-steer state in the third determining process, and the fourth step includes a thirteenth control process performed when the vehicle is in the oversteer state in the fourth determining process, A twenty-second control process performed when the vehicle is in an understeer state in the fourth determining process, and a twenty-third control process performed when the vehicle is in a countersteering state in the fourth determining process, Characterized in that it also.

Wherein the driving force transmitted to the front wheel and the rear wheel of the automobile is distributed in a range of 7: 3 to 8: 2, and the driving force transmitted to the outer wheel of the rear wheel of the automobile is transmitted to the inner wheel of the rear wheel of the automobile, And the twin clutch is controlled so as to be smaller than the first clutch.

Wherein the twelfth control process is performed such that the driving force deviation transmitted to the front wheels and the rear wheels of the automobile is distributed within 5% and the driving force transmitted to the rear wheel outer wheel of the automobile is greater than the driving force transmitted to the rear wheel inner wheel of the automobile. And the twin clutch is controlled.

Wherein the thirteenth control process is performed such that the driving force deviation transmitted to the front wheels and the rear wheels of the automobile is distributed within 5% and the driving force transmitted to the outer ring of the rear wheel of the automobile is greater than the driving force transmitted to the inner wheel of the rear wheel of the automobile. And the twin clutch is controlled.

The twenty-first control process is performed such that the driving force transmitted to the front wheels and the rear wheels of the automobile is distributed in a ratio of 6: 4 to 7: 3, and the driving force deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel is less than 5% Controls the twin clutch so as to control the brakes of the vehicle such that the braking force applied to the outer ring of the rear wheel of the vehicle is greater than the braking force applied to the inner wheel of the rear wheel of the vehicle.

The twenty-second control process controls the twin clutch so that a drifting force deviation transmitted to the front wheels and rear wheels of the automobile and a driving force deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel of the automobile are respectively less than 5% The braking force applied to the rear wheel outer ring of the vehicle is smaller than the braking force applied to the inner wheel of the rear wheel of the automobile.

The 23rd control process is performed such that the driving force transmitted to the front wheels and the rear wheels of the automobile is distributed in a ratio of 6: 4 to 7: 3, and the drivability deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel is less than 5% Controls the twin clutch so as to control the brakes of the vehicle such that the braking force applied to the outer ring of the rear wheel of the vehicle is greater than the braking force applied to the inner wheel of the rear wheel of the vehicle.

The 4WD system control method according to the present invention has the following effects.

First, stable control is possible even under running under difficult conditions, which is difficult to cope with with general feedback control.

Second, the accident can be prevented by effectively controlling the movement of the vehicle that deviates from the operation of the driver.

1 is a diagram showing a normal motion of a car,
FIG. 2A is a diagram showing a movement of a vehicle in an oversteer state,
FIG. 2B is a diagram showing a movement of a vehicle in an understeer state,
Fig. 2C is a diagram showing movement of a car in a counter-steered state,
FIG. 3A is a view illustrating a control of movement of an automobile in an oversteer state according to an embodiment of the present invention;
FIG. 3B is a view illustrating a control of movement of a vehicle in an understeer state according to an embodiment of the present invention;
FIG. 3C is a view illustrating control of movement of a vehicle in a counter-steered state according to an embodiment of the present invention;
4 is a flowchart illustrating a control process according to an embodiment of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, a method for controlling a 4WD system according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIGS. 2A, 2B and 2C are diagrams showing abnormal behaviors of a vehicle at the time of curve driving, and FIGS. 3A, 3B and 3C are diagrams showing control methods according to respective abnormal behaviors And FIG. 4 is a flowchart specifically showing a control method according to the present invention.

As shown in FIG. 1, when the driver operates the curve precisely, the vehicle 100 can rotate along the normal orbit 140. However, when the road surface condition is uneven due to weather such as rain or snow, oil caused by an accident, damaged parts, or the like, the vehicle 100 may exhibit abnormal behavior even if the driver performs an accurate operation.

That is, the oversteer 120 in which the automobile 100 is deflected toward the inside of the curve due to excessive rotation as shown in FIG. 2A, the lack of rotation of the automobile 100 as shown in FIG. 2B, The countersteering 130 in which the direction of movement of the vehicle 100 is inconsistent with the forward direction of the automobile 100 as shown in Fig. 2C may occur.

In order to solve such a problem, the present invention introduces feed-forward control as well as feed-back control to improve driving stability under adverse conditions.

As shown in FIG. 4, the present invention includes a first step S100 of receiving external information affecting the running of a vehicle, a second step S200 of determining a running mode based on external information, A third step S300 of determining an abnormal mode indicating an abnormal behavior deviating from the will of the vehicle; and a fourth step S400 of controlling the vehicle when an abnormal mode is generated.

In the first step S100, external information such as road surface information, accident information, weather information, and the like is received and transmitted to the control unit of the vehicle.

The information of the road surface can receive the inclination of the road surface, the wrapping condition, the wear, the place of the damage, etc., and the accident information can receive the information of the accident location, the oil leaked or scattered fragments, Rainfall, rainfall, temperature, and humidity.

Such external information may be received through a navigation device, a communication device, or the like installed in an automobile, or may be received through an externally mounted navigation device or a smartphone of a passenger.

The second step S200 includes a first determining step S210 for determining whether there is a bad condition on the basis of the external information and determining an emergency traveling mode or a general driving mode on the basis of the external information, And a second determination step (S220) of determining whether the feedback control through the information sensed by the sensor of the vehicle is performed within the error range during the actual driving and finally determining the emergency driving mode or the general driving mode do.

The second determination process (S220) may include a twenty-first determination process (S221) performed when the general running mode is determined during the first determination process (S210), and a second determination process if the emergency running mode is determined during the first determination process And a twenty-second judgment process (S222) to be performed.

In the twenty-first determination process (S221), the road surface friction coefficient is measured using the fact that the tire slips, and when the driver's operation and the behavior of the vehicle coincide with each other through the feedback control, The driving mode is maintained, and when the behavior of the vehicle is out of the tolerance range, the first determination process (S210) is performed again.

In the twenty-second determination process (S222), the road surface friction coefficient is measured using the occurrence of slip of the tire, and when the operation of the driver and the behavior of the vehicle coincide with each other through the feedback control, (Step S221), and if the behavior of the vehicle is out of the error range and exhibits an abnormal behavior, the third step (S300) is performed.

That is, in the second step S200, the general driving mode and the emergency driving mode are firstly determined using the feedforward method based on the external information previously received, and then it is determined whether the normal control is possible by the feedback method, Mode or the emergency driving mode.

If the general driving mode or the emergency driving mode is finally determined in the second step S200, in the third step S300, it is determined whether the vehicle indicates an abnormal behavior such as oversteering, understeer, and countersteering while driving the curve section do.

Under normal circumstances, the 4WD system delivers the same level of driving and braking power to the front and rear wheels, the left and the right wheels of the vehicle, so there is no specific deviation between the four wheels. However, when an abnormal behavior such as oversteering, understeer, and countersteering occurs, the driving force or the braking force transmitted to the four wheels is controlled to solve the abnormal behavior and restore the normal running state, .

In the third step S300, it is determined that the vehicle is in the emergency driving mode through the third determination process (S310) and the twenty-second determination process (S222) performed when the normal driving mode is determined through the twenty-first determination process (S221) And a fourth determination process (S320) in which the first determination process is performed.

That is, the third determination process (S310) is a process for determining whether an oversteer, an understeer, and a countersteering occur in the normal driving mode. In a fourth determination process (S320), the oversteering, understeering, Is generated.

If any of oversteer, understeer, and countersteering occurs in the third determination process (S310) or the fourth determination process (S320), the fourth step (S400) is performed.

In the fourth step S400, an eleventh control process S411, a twelfth control process S412, and a thirteenth control process S412 are performed when the oversteer, the understeer, and the countersteering occur, respectively, The twenty-first control process (S421), the twenty-second control process (S422), and the twenty-third control process (S422) performed when the oversteer, the understeer and the countersteering are generated through the control process S413 and the fourth determining process S320, And a control process (S423).

Each of these control procedures is shown in detail in 3A, 3B and 3C. 3A shows a control method when an oversteer is generated in an ordinary running mode, FIG. 3B shows a control method when an oversteer is generated in an emergency running mode, FIG. 3B shows a normal running mode, FIG. 3C is a control method when the countersteering is generated in the normal running mode, and FIG. 3B is a control method when the countersteering is generated in the emergency running mode, respectively. At this time, the driving force and the braking force distributed to the driving system of the vehicle shown in Figs. 3A, 3B and 3C are shown based on the case where the vehicle is turning to the right.

The eleventh control process S411 is performed when oversteering occurs in the normal driving mode and 70 to 80% of the total driving force output from the transmission 210 is distributed to the front wheels 231 and 232 and the rest is transmitted to the rear wheels 233, 234, which is distributed to the inner wheel 234 of the rear wheel, that is, the inner rear wheel of the curve, from the driving force distributed to the outer wheel 233 of the rear wheel, i.e., the rearward wheel of the curve in the twin clutch 220, Is controlled to be larger.

A yaw rate in the left direction can be formed in the automobile by making a difference such that the driving force distributed to the rear wheel inner ring 234 is greater than the rear wheel outer wheel 233, So that the vehicle leaving the road can be returned to the normal position.

The twelfth control process S412 is performed when an understeer occurs in the normal running mode and the half of the total driving force output from the transmission 210 is distributed to the front wheels 231 and 232 and the rear wheels 233 and 234, The driving force that is distributed from the twin clutch 220 to the inner wheel 234 of the rear wheel is smaller than the driving force which is distributed to the outer wheel 233 of the rear wheel.

A yaw rate in the right direction can be formed in the automobile by making the driving force distributed to the rear wheel inner wheel 234 smaller than the rear wheel outer wheel 233, The vehicle deviating from the road can be returned to the normal position.

The thirteenth control process (S413) is performed when the countersteering occurs in the normal running mode and the half of the total driving force output from the transmission 210 is distributed to the front wheels 231 and 232 and the rear wheels 233 and 234 respectively, The driving force that is distributed from the twin clutch 220 to the inner wheel 234 of the rear wheel is smaller than the driving force which is distributed to the outer wheel 233 of the rear wheel. That is, similar to the eleventh control process S411, the driving force deviation between the outer wheel 233 of the rear wheel and the inner wheel 234 of the rear wheel is controlled to be greater than that of the eleventh control process S411. 2C, since the vehicle is in an overspeed state, an excessive yaw rate is generated to forcibly turn the automobile, and the rear wheel outer wheel 233 and the rear wheel outer wheel 233, respectively.

The twenty-first control process S421 is performed when oversteering occurs in the emergency running mode. The twenty-first control process S421 is performed when oversteering occurs in the emergency running mode, and 60 to 70% of the total driving force output from the transmission 210 is distributed to the front wheels 231 and 232, 234 so that the driving force distributed to the outer wheel 233 and the inner wheel 234 of the rear wheel in the twin clutch 220 is controlled to be the same. During the 21st control process (S421), the braking force is applied to the front wheels 231 and 232 and the rear wheels 233 and 234 to decelerate the speed, and in particular, the braking force applied to the outer wheel 233 of the rear wheel, The yaw rate in the left direction can be generated in the automobile by controlling the braking force greatly compared to the added braking force. As a result, as shown in FIG. 2A, the vehicle excessively turning to the right can return the automobile leaving the road to the normal position.

The twenty-second control process (S422) is performed when an understeer occurs in the emergency running mode. The twenty-second clutch process 220 distributes the entire driving force output from the transmission 210 to the front wheels and the rear wheels, To the outer wheel 233 and the inner wheel 234, respectively. During the twenty-second control process (S422), the braking force is applied to the front wheels 231 and 232 and the rear wheels 233 and 234 to decelerate the speed, and in particular, the braking force applied to the inner wheel 234 of the rear wheel, The yaw rate in the right direction can be generated in the automobile by controlling the braking force to be greater than the added braking force. As a result, as shown in FIG. 2B, the vehicle deviating from the road due to insufficient rotational force can be returned to the normal position.

The 23rd control process S423 is performed when a countersteering occurs in the emergency running mode and 60 to 70% of the total driving force output from the transmission 210 is distributed to the front wheels 231 and 232, 234 so that the driving force distributed to the outer wheel 233 and the inner wheel 234 of the rear wheel in the twin clutch 220 is controlled to be the same. On the other hand, during the 23rd control process (S423), the braking force is applied to the front wheels 231 and 232 and the rear wheels 233 and 234 to decelerate the speed, and in particular, the braking force added to the inner wheel 234 of the rear wheel The yaw rate in the right direction can be generated in the automobile by controlling the braking force to be greater than the added braking force. Thus, the vehicle can be returned to the normal position by generating an excessive yaw rate in the counter-steered vehicle which behaves as shown in FIG. 2C.

That is, in the normal running mode, if the posture and position of the vehicle are controlled by distributing the driving force of the vehicle to generate the yaw rate, in the emergency running mode, the yaw rate is generated through the distribution of the braking force rather than the driving force distribution of the vehicle. Thereby controlling the posture and position of the vehicle.

As described above, when the yaw rate is generated and the vehicle is controlled by using the deviation of the braking force in the emergency running mode, the overall speed of the vehicle is reduced and stable running is possible, so that stability can be maintained even during traveling under the bad conditions.

However, in the above-described control processes, the drive forces distributed to the front wheels 231 and 232 and the rear wheels 233 and 234 are controlled equally, or the driving forces distributed to the outer and inner wheels 233 and 234 of the rear wheels are made equal Control is a perfect 1: 1 ratio, but in reality, it can be difficult to distribute 1: 1 ratios by internal and external factors. Therefore, when the deviation of the driving force to be distributed is 5% or less, it may be judged that it is distributed in equal or half. If the deviation exceeds 5%, a significant level of yaw rate will occur during driving of the vehicle, so that the driving stability of the vehicle may be degraded.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

100: car 110: understeer
120: Over Steer 130: Counter Steer
140: Normal track 210: Transmission
220: Twin clutch 231, 232: Front wheel
233: rear wheel (outer wheel) 234: rear wheel (inner wheel)
S100: first step S200: second step
S210: First judgment process S220: Second judgment process
S221: the 21st judgment process S222: the 22nd judgment process
S300: third step S310: third judgment process
S320: fourth determination process S400: fourth step
S411: eleventh control process S412: twelfth control process
S413: thirteenth control process S421: twenty-first control process
S422: Twenty-second control process S423: Twenty-third control process

Claims (12)

A control method of a 4WD vehicle equipped with a twin clutch,
A first step of receiving external information that affects the driving of the automobile;
A second step of determining a traveling mode using the external information received in the first step;
A third step of determining occurrence of an anomaly mode in which the vehicle deviates from a preset normal trajectory at the time of traveling the curve section; And
Wherein the operation of the twin clutch is controlled in accordance with the traveling mode determined in the second step and the abnormal mode determined in the third step and the driving force between the front wheel and the rear wheel of the automobile and the driving force between the rear wheel outer wheel and the rear wheel inner wheel And a fourth step of distributing a driving force of the first clutch
The first step includes receiving at least one of road surface information, accident information, and weather information of the road and transmitting the information to the control unit of the vehicle;
Wherein the second step comprises: determining a driving mode using the information transmitted to the control unit in the first step;
The second step may include a first determining step of determining an accident risk by using the information transmitted to the controller in the first step and selecting an emergency driving mode or a general driving mode; And a second determining step of determining whether or not the actual operation information of the vehicle coincides with each other.
delete delete The method according to claim 1,
The second determination process may include a twenty-first determination process performed when the general mode is determined in the first determination process and a twenty-second determination process performed when the mode is determined to be an emergency running mode in the first determination process ,
Wherein the 21st decision step performs the third step when the handling information of the automobile matches the operation information and performs the first decision step when the operation information does not match,
Wherein the twenty-second determination process performs the twenty-first determination process when the handling information of the vehicle and the motion information coincide with each other, and performs the third process when the motion information does not coincide with the motion information.
The method of claim 4,
Wherein the third step compares the handling information of the automobile with the operation information to determine whether the automobile is in an oversteer, an understeer, or a countersteering state.
The method of claim 5,
The third step may include a third determination step performed when the third step is entered in the twenty first determination step and a fourth determination step performed when the third step is entered in the twenty second determination step and,
The eleventh control process is performed when the vehicle is in the oversteer state in the third determining process. The twelfth control process is performed when the automobile is in the understeer state in the third determining process. And a thirteenth control process performed when the vehicle is in the counter-steer state in the third determination process,
Wherein the fourth step comprises a twenty-first control step performed when the vehicle is in an oversteer state in the fourth determining step, a twenty-second control step performed when the vehicle is in an understeer state in the fourth determining step, And a 23 < th > control process performed when the vehicle is in the counter-steer state in the fourth determination process.
The method of claim 6,
Wherein the driving force transmitted to the front wheel and the rear wheel of the automobile is distributed in a range of 7: 3 to 8: 2, and the driving force transmitted to the outer wheel of the rear wheel of the automobile is transmitted to the inner wheel of the rear wheel of the automobile, And the twin clutch is controlled so as to be smaller than a predetermined value.
The method of claim 6,
Wherein the twelfth control process is performed such that the driving force deviation transmitted to the front wheels and the rear wheels of the automobile is distributed within 5% and the driving force transmitted to the rear wheel outer wheel of the automobile is greater than the driving force transmitted to the rear wheel inner wheel of the automobile. And the twin clutch is controlled.
The method of claim 6,
Wherein the thirteenth control process is performed such that the driving force deviation transmitted to the front wheels and the rear wheels of the automobile is distributed within 5% and the driving force transmitted to the outer ring of the rear wheel of the automobile is greater than the driving force transmitted to the inner wheel of the rear wheel of the automobile. And the twin clutch is controlled.
The method of claim 6,
The twenty-first control process is performed such that the driving force transmitted to the front wheels and the rear wheels of the automobile is distributed in a ratio of 6: 4 to 7: 3, and the driving force deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel is less than 5% Controls the twin clutch so as to control the brakes of the vehicle such that the braking force applied to the outer ring of the rear wheel of the vehicle is larger than the braking force applied to the inner wheel of the rear wheel of the vehicle.
The method of claim 6,
The twenty-second control process controls the twin clutch so that a drifting force deviation transmitted to the front wheels and rear wheels of the automobile and a driving force deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel of the automobile are respectively less than 5% Wherein the braking force applied to the rear wheel outer ring of the vehicle is smaller than the braking force applied to the inner wheel of the rear wheel of the automobile.
The method of claim 6,
The 23rd control process is performed such that the driving force transmitted to the front wheels and the rear wheels of the automobile is distributed in a ratio of 6: 4 to 7: 3, and the drivability deviation transmitted to the rear wheel outer wheel and the rear wheel inner wheel is less than 5% Controls the twin clutch so as to control the brakes of the vehicle such that the braking force applied to the outer ring of the rear wheel of the vehicle is larger than the braking force applied to the inner wheel of the rear wheel of the vehicle.

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