KR101739230B1 - Vehicle speed calculate method for slip control of four wheel drive vehicle - Google Patents

Abstract

The present invention relates to a vehicle speed calculation method for a four-wheel drive vehicle slip control, in which a wheel speed at an n-th time point, a wheel speed at an n + 1th time point later than the n-th time point, A slip determining step of determining whether or not slip has occurred at the (n + 1) th time point by the acceleration between the first and second timings; And a vehicle speed calculating step of calculating a vehicle speed at the (n + 1) th time point according to a result of the determination in the slip determining step, wherein in the vehicle speed determining step, Th wheel speed at the (n + 1) th time point is determined as the vehicle speed at the (n + 1) -th time point, the slip determining step determines that the slip has occurred at the (n + When the wheel speed at the (n + 1) th time point is greater than the wheel speed at the n-th time point and the wheel speed upper limit at the (n + 1) th time point calculated as the acceleration between the n-th time point and the th wheel speed at the (n + 1) th time point is determined as the vehicle speed at the (n + 1) th time point, The wheel speed at the n-th time point and the wheel speed at the n-th time point Is less than the wheel speed of the lower limit of the first n + 1 time calculated in between the acceleration wherein said n + 1 time, it is possible to calculate the wheel speed of the lower limit of said n + 1 time to the speed of said n + 1 time. Thus, the accuracy of the calculated vehicle speed can be improved.

Description

[0001] VEHICLE SPEED CALCULATE METHOD FOR SLIP CONTROL OF FOUR WHEEL DRIVE VEHICLE [0002]

The present invention relates to a vehicle speed calculation method for vehicle slip control, and more particularly, to a vehicle speed calculation method for vehicle slip control, which calculates a vehicle speed required for slip control in accordance with slip occurrence, The present invention relates to a vehicle speed calculation method for a four-wheel-drive vehicle slip control.

Generally, the four-wheel-drive vehicle improves the stability of the vehicle running through slip control when the vehicle slips.

This slip control requires the speed of the vehicle (hereinafter, vehicle speed), and the vehicle speed is calculated by a separate vehicle speed calculation method.

1 is a flowchart showing a vehicle speed calculation method for a conventional four-wheel-drive vehicle slip control.

1, a conventional vehicle speed calculation method for a four-wheel drive vehicle slip control system includes a slip determination step S2 for determining whether a slip occurs, and a vehicle speed calculation step S2 for calculating a vehicle speed according to a result determined in the slip determination step S2 And a vehicle speed calculating step S3.

In the slip determination step S2, whether or not the slip is determined is determined by comparing the wheel speed of the vehicle with the acceleration of the vehicle. More specifically, in the slip determining step S2, it is determined that the slip does not occur when the rate of increase of the wheel speed is equal to the acceleration, by comparing the rate of increase of the wheel speed with the acceleration. It is determined that slip has occurred.

In the vehicle speed calculation step S3, when it is determined that the slip occurs in the slip determination step S2, the vehicle speed is calculated by integrating the acceleration, and when it is determined that the slip does not occur in the slip determination step S2 The wheel speed is calculated as the vehicle speed.

However, in the conventional vehicle speed calculation method for four-wheel-drive vehicle slip control, the accuracy of the calculated vehicle speed is deteriorated. Specifically, there has been a problem in that so-called jumping occurs when the slip judgment is changed (in the case where the slip is not generated, or when the slip judgment is changed to the slip occurrence state or vice versa), and the calculated vehicle speed is rapidly fluctuated. Then, there is a problem that an error occurs in the slip judgment and the vehicle speed is calculated incorrectly. More specifically, for example, when the vehicle is tested on a chassis dynamo, the vehicle speed should be calculated to be equivalent to the wheel speed since no slip occurs. However, since the acceleration is measured as zero (0) It is determined that a slip occurs in the vehicle, and the value obtained by integrating the acceleration is calculated as the vehicle speed, thereby erroneously calculating the vehicle speed. In addition, when longitudinal acceleration is used as the acceleration, lateral slip occurs, sudden change of the closing speed due to the spin of the vehicle occurs, or if the backing rate of the backing plate or the steel plate is disturbed, There is a problem that the judgment is wrong and the vehicle speed is calculated in error.

Korean Patent Publication No. 10-1345841

Therefore, it is an object of the present invention to provide a vehicle speed calculation method for four-wheel drive vehicle slip control, which can improve the accuracy of the calculated vehicle speed.

In order to achieve the above object, the present invention is characterized in that, in order to achieve the above-described object, the present invention is characterized in that the wheel speed at the n-th time point, the wheel speed at the (n + 1) th time point later than the n-th time point, Determining whether a slip occurs at the (n + 1) th time point; And a vehicle speed calculating step of calculating a vehicle speed at the (n + 1) th time point according to a result of the determination in the slip determining step, wherein in the vehicle speed determining step, Th wheel speed at the (n + 1) th time point is determined as the vehicle speed at the (n + 1) -th time point, the slip determining step determines that the slip has occurred at the (n + When the wheel speed at the (n + 1) th time point is greater than the wheel speed at the n-th time point and the wheel speed upper limit at the (n + 1) th time point calculated as the acceleration between the n-th time point and the th wheel speed at the (n + 1) th time point is determined as the vehicle speed at the (n + 1) th time point, The wheel speed at the n-th time point and the wheel speed at the n-th time point Th wheel speed lower limit at the (n + 1) th time point is calculated as the vehicle speed at the (n + 1) th time point when the wheel speed lower limit at the (n + 1) Wheel drive vehicle slip control system for a four-wheel drive vehicle.

The wheel speed upper limit at the (n + 1) th time point is calculated as the maximum value of the speed range at which the wheel speed at the n-th time point can be changed by the acceleration between the n-th time point and the (n + 1) The wheel speed lower limit of the starting point can be calculated as the minimum value of the speed range in which the wheel speed at the n-th time point can be changed by the acceleration between the n-th time point and the (n + 1)

Wherein the vehicle speed computing step includes a first calculating step of calculating a wheel speed at the (n + 1) th time point as the vehicle speed at the (n + 1) th time point when it is determined that the slip does not occur at the A vehicle speed calculating step; And when it is determined that the slip has occurred at the (n + 1) th time point in the slip determination step and the wheel speed at the (n + 1) th time point is greater than the wheel speed upper limit at the A second vehicle speed calculating step of calculating an upper limit of the wheel speed at the (n + 1) th time point as a vehicle speed at the (n + 1) th time point; And when it is determined that the slip has occurred at the (n + 1) th time point in the slip determination step and the wheel speed at the (n + 1) th time point is smaller than the wheel speed lower limit at the (n + And a third vehicle speed calculating step of calculating a lower wheel speed at a first time point as a vehicle speed at the (n + 1) th time point.

The sleep determination step determines whether an increase rate of the wheel speed between the n-th time point and the (n + 1) -th time point is included in a predetermined range based on the acceleration between the n-th time point and the (n + 1) A first sleep determination step; A second sleep determination step of determining whether the wheel speed at the (n + 1) th time point is included between the wheel speed upper limit at the (n + 1) th time point and the wheel speed lower limit at the (n + 1) th time point; And a third sleep determination step of determining whether or not slip occurs at the (n + 1) th time point according to a determination result of the first slip determination step and the second slip determination step.

The slip determining step determines that the rate of increase of the wheel speed between the n-th point and the (n + 1) -th point in the first slip determining step is within a predetermined range based on the acceleration between the n-th point and the And the wheel speed at the (n + 1) th time point is not included between the wheel speed upper limit at the (n + 1) th time point and the wheel speed lower limit at the (n + 1) th time point in the second sleep determination step The first slip determining step determines that a slip has occurred at the (n + 1) th time point in the third slip determining step, and the increasing rate of the wheel speed between the nth time point and the (n + Th wheel speed at the (n + 1) th time point is determined to be included in a predetermined range based on the acceleration between the n-th time point and the (n + 1) Speed upper limit and phase When determining that the included between n + 1 the wheel speed lower limit of the start point, the first may be determined in the third determination step to be not slip a slip occurs at the time of the first n + 1.

The slip determining step determines that the rate of increase of the wheel speed between the n-th point and the (n + 1) -th point in the first slip determining step is within a predetermined range based on the acceleration between the n-th point and the Or the wheel speed at the (n + 1) th time point is not included between the wheel-speed upper limit at the (n + 1) th time point and the wheel speed lower limit at the (n + 1) th time point in the second sleep determination step Wherein the controller determines that a slip has occurred in the third slip determination step and determines that the rate of increase of the wheel speed between the n-th time point and the (n + 1) The wheel speed at the (n + 1) th time point is determined to be included in the predetermined range based on the acceleration between the (n + 1) th time point and the wheel speed upper limit at the (n + Wheel at one point It can be determined that the slip does not occur in the third slip determination step.

The vehicle speed computing step determines that a slip has occurred at the (n + 1) th time point in the slip determining step, but the wheel speed at the (n + 1) And a fourth vehicle speed calculating step of calculating the wheel speed at the (n + 1) th time point as the vehicle speed at the (n + 1) th time point when it is determined to be included between the lower wheel speed limits at the time point of +1.

The method according to any one of claims 1 to 3, wherein before the slip determining step, the wheel speed at the nth time point received from the sensor, the wheel speed at the (n + 1) th time point and the acceleration between the nth time point and the Determining whether the vehicle input signal is normal or not;

In the slip determination step, the acceleration of the wheel speed at the n-th time point, the wheel speed at the (n + 1) th time point, and the acceleration between the n-th time point and the (n + 1) Wherein the step of determining whether the vehicle is in the normal range includes executing the preceding one of the first slip determining step and the second slip determining step, When it is determined that at least one of the wheel speed at the +1 time point and the acceleration between the nth time point and the (n + 1) th time point is not included in each predetermined normal range, .

After the vehicle speed calculation step is completed, it may be returned to the step of determining whether the vehicle input signal is normal.

The vehicle includes a plurality of wheels, and the wheel speed at the n-th time point is set to the rotational speed of the wheel whose rotational speed is the third highest among the plurality of wheels at the n-th time point, The speed may be set to the rotation speed of the wheel that is the third one of the plurality of wheels at the (n + 1) th time point.

The vehicle includes a longitudinal acceleration sensor for measuring the longitudinal acceleration of the vehicle and a lateral acceleration sensor for measuring the lateral acceleration of the vehicle, and the acceleration between the n-th time point and the (n + 1) And may be set as a vector sum of the acceleration and the lateral acceleration.

The vehicle speed calculation method for four-wheel drive vehicle slip control according to the present invention is characterized in that when it is determined that slip has occurred and the wheel speed is not included between the upper and lower limits of the wheel speed, The upper limit or lower limit of the vehicle speed can be calculated. Thus, the accuracy of the calculated vehicle speed can be improved.

1 is a flowchart showing a vehicle speed calculation method for a conventional four-wheel-drive vehicle slip control,
2 is a flowchart showing a vehicle speed calculation method for a four-wheel drive vehicle slip control according to an embodiment of the present invention;
FIG. 3 is a diagram showing a wheel speed, a wheel speed upper limit, and a wheel speed lower limit in the second slip determination step of FIG. 2,
4 to 6 are flowcharts showing vehicle speed calculation methods for four-wheel drive vehicle slip control according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle speed calculation method for a four-wheel drive vehicle slip control according to the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a flowchart showing a vehicle speed calculation method for a four-wheel drive vehicle slip control according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between a wheel speed, a wheel speed upper limit, In each case.

2 and 3, a vehicle speed calculation method for four-wheel drive vehicle slip control according to an embodiment of the present invention includes calculating a wheel speed at an n-th point of time t0 (hereinafter referred to as an n-th wheel speed) (Hereinafter referred to as an (n + 1) -th wheel speed) WS1 and an n-th point of time t0, which are later than the n-th point of time t0, (S 1) determining whether the vehicle input signal is normal or not, and determining whether acceleration (A) (hereinafter referred to as acceleration) between the (n + 1) th time point t 1 is included in the predetermined normal range; A slip determining step S2 of determining whether a slip occurs in the (n + 1) th time point t1 with the nth wheel speed WS0, the (n + 1) th wheel speed WS1 and the acceleration A; And a vehicle speed calculating step S3 for calculating a vehicle speed of the (n + 1) th time point t1 according to the result of the determination in the slip determining step S2.

Here, the wheel speeds WSn and WSn + 1 are measured by a wheel speed sensor mounted on the vehicle, and the acceleration A can be measured by an acceleration sensor mounted on the vehicle.

The wheel speed sensor and the acceleration sensor perform sampling according to the time, and the nth sampling point is the n-th sampling point t0, and the (n + 1) (t1) at the (n + 1) th time point.

On the other hand, the vehicle includes a plurality of wheels (typically, four wheels), and the wheel speed sensors can be mounted on each wheel. That is, the wheel speed can be measured for each wheel. Here, in the present embodiment, the n-th wheel speed WS0 is the rotational speed of the third highest rotational speed of the plurality of wheels at the n-th time point t0, WS1 may be the rotational speed of the third highest rotational speed of the plurality of wheels at the (n + 1) th time point t1. Here, the wheel having the third highest rotation speed among the plurality of wheels may vary according to the driving state (for example, the plurality of wheels are referred to as first to fourth wheels, and at the n-th time point t0 Thirdly, even if the wheel having a high rotation speed is the second wheel, the wheel having the third highest rotation speed at the (n + 1) th time point t1 may still be the second wheel, Three wheels, and the fourth wheel). The use of the rotational speed of the third highest rotational speed among the plurality of wheels at each point of time is preferably performed in the first, second, and fourth rotational speeds The wheel speed of the wheel with the third highest rotation speed is similar to the actual vehicle speed.

On the other hand, the acceleration sensor includes a longitudinal acceleration sensor for measuring the longitudinal acceleration of the vehicle and a lateral acceleration sensor for measuring the lateral acceleration of the vehicle, and the acceleration A ) May be a vector sum of the longitudinal acceleration and the lateral acceleration.

The step of determining whether or not the vehicle input signal is normal is a step of verifying the reliability of the wheel speed information and the acceleration information before the sleep determination step S2 for more accurate vehicle speed calculation, It is possible to prevent a wrong calculation.

The step (S1) of determining whether or not the vehicle input signal is normal includes determining that the n-th wheel speed WS0, the n + 1-th wheel speed WS1, and the acceleration A are included in a predetermined normal range, (N + 1) th wheel speed (WS1) and the acceleration (A) are compared with a predetermined pre-determined normal state (S21) (More precisely, it is determined that the slip does not occur in the third slip determination step S23), the third slip determination step S23 may be formed.

The vehicle input signal normal state determination step S1 may be configured to return to the step S1 of determining whether the vehicle input signal is normal after the vehicle speed calculation step S3 is completed.

The slip determining step S2 determines whether or not the wheel speed increasing rate (hereinafter referred to as wheel speed increasing rate)? WS /? T = (WS1 - WS0) from the nth wheel speed WS0 to the ) / (t1 - t0)) is included in a predetermined range (acceleration (A) ± error: acceleration (A) when the error is set to zero) based on the acceleration (A) A first sleep determination step S21; Determining whether the n + 1-th wheel speed WS1 is included between the upper limit WS1max of the n + 1-th wheel speed and the lower limit WS1min of the n + 1-th wheel speed S22); And whether or not the slip occurrence of the (n + 1) th time point t1 according to the determination result of the first slip determination step S21, the second sleep determination step S22, And a third sleep determination step S23 for determining a sleep state. Here, the upper limit WS1max of the (n + 1) th wheel speed and the lower limit WS1min of the (n + 1) th wheel speed may be calculated from the nth wheel speed WS0 and the acceleration A. Specifically, the upper limit WS1max of the n + 1-th wheel speed is calculated as the maximum value of the speed range in which the n-th wheel speed WS0 can be changed by the acceleration A, The lower limit WS1min of the n-th wheel speed WS0 can be calculated as the minimum value of the speed range in which the n-th wheel speed WS0 can be changed by the acceleration (A).

The sleep determination step S2 determines whether the vehicle input signal is normal or not in the first slip determination step S21 when the information on the vehicle input signal is normal in step S1, If it is determined that a slip has occurred in the determination step S21, it is determined whether or not the slip occurs in the second slip determination step S22. If it is determined that the slip occurs in the second slip determination step S22 It may be determined that the slip is finally generated in the third slip determination step S23.

The sleep determination step S2 determines whether at least one of the various kinds of information is abnormal in the step S11 of determining whether the vehicle input signal is normal or that no slip occurs in the first slip determination step S21 Or if it is determined that the slip does not occur in the second slip determination step S22, it may be determined that the slip is not finally generated in the third slip determination step S23.

More specifically, the slip determination step S2 determines whether or not the n-th wheel speed WS0, the n + 1-th wheel speed WS1, and the acceleration A in the step S- (N + 1) th wheel speed (WS0), the (n + 1) th wheel speed, and the (n + 1) th wheel speed in the step S21, (T1) at the third sleep determination step (S23) when it is determined that at least one of the first wheel speed Is not generated.

The slip determining step S2 is a step of determining whether the wheel speed increasing rate? WS /? T is within a predetermined range (acceleration A) based on the acceleration A in the first slip determining step S21, (S22) when it is determined that the error is not included in the acceleration (A) when the error is set to zero (0), and the wheel speed increase rate (A)) is included in a predetermined range (acceleration (A) + error: acceleration (A) when the error is set to zero) based on the acceleration (A) It may be determined that no slip occurs at the (n + 1) th time point t1 in the slip determination step S23.

The slip determining step S2 is a step of determining whether the n + 1-th wheel speed WS1 is higher than the upper limit WS1max of the n + 1-th wheel speed and the n + 1 The first slip determination step S22 determines that a slip has occurred at the (n + 1) th time point t1 in the third slip determination step S23 when it is determined that the slip is not included between the lower limit WS1min of the wheel speed 1) wheel speed WS1 is included between the upper limit WS1max of the (n + 1) th wheel speed and the lower limit WS1min of the (n + 1) th wheel speed at the third sleep determination step (S23), it is determined that no slip occurs at the (n + 1) th time point t1.

The vehicle speed calculation step S3 calculates the vehicle speed Ns by adding the (n + 1) th wheel speed WS1 to the (n + 1) th wheel speed WS1 when it is determined that the slip has not occurred at the (n + 1) th time t1.

The vehicle speed computing step S3 is a step of determining whether a slip has occurred at the (n + 1) th time point t1 in the slip determining step S2, (WS1max) of the (n + 1) th wheel speed may be calculated as the vehicle speed of the (n + 1) th time point t1 when the upper limit of the (n + 1) th wheel speed is greater than the upper limit WS1max.

The vehicle speed computing step S3 is a step of determining whether a slip has occurred at the (n + 1) th time point t1 in the slip determining step S2, (WS1min) of the (n + 1) th wheel speed is calculated as the vehicle speed of the (n + 1) th time point t1 when the lower limit of the (n + 1) th wheel speed is smaller than the lower limit WS1min of the (n + 1) th wheel speed.

That is, in the third slip determination step S3, when the slip is not generated at the (n + 1) th time point t1 in the third slip determination step S23, the (n + 1) A first vehicle speed calculating step (S31) of calculating a vehicle speed at the (n + 1) th time point (t1); The first slip determining step S23 determines that a slip has occurred at the (n + 1) th time point t1 and the (n + l) th wheel speed WS1 is greater than the upper limit A second vehicle speed calculating step (S32) of calculating an upper limit (WS1max) of the (n + 1) th wheel speed as a vehicle speed of the (n + 1) th time point (t1); And the slip determining step S2 determines that a slip has occurred at the (n + 1) th time point t1, and when the (n + 1) th wheel speed WS1 is less than the lower limit (WS1min) Th wheel speed to a vehicle speed of the (n + 1) -th time point t1 when it is determined that the nth wheel speed is smaller than the first wheel speed.

The vehicle speed calculating step S3 is a step of calculating the vehicle speed of the vehicle when any one of the first vehicle speed computing step S31, the second vehicle speed computing step S32, and the third vehicle speed computing step S33 is completed And then return to the step of determining whether the vehicle input signal is normal or not.

The vehicle speed calculation method for four-wheel drive vehicle slip control according to this embodiment of the present invention according to the present embodiment is not limited to simply calculating the vehicle speed by integrating the acceleration A when the slip is judged to have occurred, It is possible to calculate the vehicle speed in consideration of whether it is included between the upper limit (WS1max) and the lower limit (WS1min) of the wheel speed. That is, when the wheel speed WS1 is not included between the upper limit WS1max and the lower limit WS1min of the wheel speed, it is possible to limit the increase or decrease amount of the wheel speed so that the upper limit WS1max of the wheel speed or the lower limit (WS1min) can be calculated as the vehicle speed. Thus, the vehicle speed can be accurately calculated.

If it is determined that the slip has occurred at the (n + 1) th time point t1 after the determination that the slip has not occurred at the nth time point t0, or if the slip is detected at the nth time point t0 (I.e., when it is determined that the slip does not occur at the (n + 1) th time point t1 after the determination that the vehicle has been generated), so-called jumping is caused and the vehicle speed calculated can be prevented from being abruptly changed.

When the wheel speed WS1 is lower than the upper limit WS1max and lower limit WS1min of the wheel speed by comparing a plurality of conditions (whether the vehicle input signal is normal or the wheel speed increase rate? WS /? T) , It is possible to improve the accuracy of the slip occurrence determination and the vehicle speed calculation.

Since the slip does not occur when the vehicle is tested in the chassis dynamo, the vehicle speed should be calculated to be equivalent to the wheel speed WS1. According to the present embodiment, in this case, in the first slip determining step S21, In the second slip determination step S22, the wheel speed WS1 is determined as the upper limit WS1max of the wheel speed, and in the second slip determination step S22, it is determined that the slip occurs due to the difference between the speed increase rate DELTA WS / DELTA t and the acceleration A, And the lower limit (WS1min), and it is determined that the slip does not occur in the third slip determining step (S23). In the vehicle speed calculating step, the wheel speed is determined as the vehicle speed The slip judgment can be made accurately and the vehicle speed can be accurately calculated.

In addition, by determining whether a slip has occurred using the wheel speed of the wheel having the third highest rotational speed among the plurality of wheels, the vehicle speed can be determined and the accuracy of slip occurrence and vehicle speed calculation can be further improved have.

Then, by using the vector sum of the longitudinal acceleration and the lateral acceleration as the acceleration (A), when the longitudinal slip occurs, when the lateral slip occurs, a sudden change in the longitudinal acceleration due to the vehicle's spin occurs It is possible to improve the accuracy of the slip occurrence determination and the vehicle speed calculation even when a disturbance of the longitudinal acceleration caused by the back plate or the steel plate occurs.

Meanwhile, in the present embodiment, the first slip determination step S21 precedes the second slip determination step S22. However, as shown in FIG. 4, the second slip determination step S22 may determine that the first slip It may precede the judgment step S21. That is, if it is determined in step S1 that the vehicle input signal is normal, it is determined that various signals are normal, the process proceeds to the second slip determination step S22, and it is determined that the slip occurs in the second slip determination step S22 The control flow proceeds to the first slip determination step S21. If it is determined that the slip has occurred in the first slip determination step S21, it is determined that the slip is finally generated in the third slip determination step S23 . In this case, the operation effect can be greatly reduced compared to the present embodiment.

Meanwhile, in the present embodiment, when it is determined that the slip has occurred in both the first slip determining step S21 and the second slip determining step S22, the third slip determining step S23 is performed. 5 and 6, if it is determined that the slip has occurred in any one of the first slip determining step S21 and the second slip determining step S22, It can be determined that the slip has finally occurred in the determination step S23. In this case, the operation effect can be greatly reduced compared to the present embodiment. In this case, even if it is determined that the slip does not occur in the second slip determination step S22 (the wheel speed is included between the upper limit WS1max and the lower limit WS1min of the wheel speed) It is determined that slip has occurred in step S21, and it can be determined that slip has finally occurred in the third slip determination step S23. At this time, the wheel speed must be calculated as the vehicle speed. The vehicle speed computing step S3 may further include a fourth vehicle speed computing step S34. That is, the vehicle speed calculating step S3 is determined to have generated a slip at the (n + 1) th time point t1 in the third slip determining step S23, but the (n + 1) Th wheel speed WS1 is included between the upper limit WS1max of the (n + 1) th wheel speed and the lower limit WS1min of the (n + 1) th wheel speed, and a fourth vehicle speed calculating step (S34) of calculating a vehicle speed of the vehicle based on the calculated vehicle speed. According to this, when the vehicle is tested in the chassis dynamo, it is determined that the slip has occurred in the first slip determination step (S21), and it is determined that the slip is finally generated in the third slip determination step, The vehicle speed can be accurately calculated by calculating the vehicle speed in step S34.

The vehicle speed calculation method shown in FIG. 5 and the vehicle speed calculation method shown in FIG. 6 are different from each other only in the difference between the first slip determination step S21 and the second slip determination step S22 Only. That is, in the vehicle speed calculation method shown in FIG. 5, the first slip determination step is performed prior to the second slip determination step (S22), and it is determined that the various signals are normal in the vehicle input signal normal determination step (S1) , It proceeds to the first slip determining step S21. If it is determined that the slip occurs in the first slip determining step S21, it is determined that the slip is finally generated in the third slip determining step S23 If it is determined that the slip has not occurred in the first slip determining step S21, the process proceeds to the second slip determining step S22. If it is determined that the slip occurs in the second slip determining step S22, It is determined that the slip has finally occurred in the third slip determination step S23 and it is determined that the slip has not occurred in the second slip determination step S22, It is determined that no slip has occurred. If it is determined in step S1 that the vehicle input signal is normal, it is determined that the slip does not occur in the third slip determination step S23 . On the other hand, the vehicle speed calculation method shown in FIG. 6 proceeds to the second slip determination step S22 when it is determined that the signals are normal in the step S11 of determining whether the vehicle input signal is normal, If it is determined in step S22 that slip has occurred, it is determined that the slip is finally generated in the third slip determination step S23. If it is determined that the slip does not occur in the second slip determination step S22, It is determined that the slip has occurred in the third slip determining step S23 if it is determined that the slip has occurred in the first slip determining step S21, If it is determined that the slip does not occur in the first slip determination step S21, it is determined that the slip does not occur in the third slip determination step S23, When the state determining step (S1) determines that the various signals is abnormal, wherein the can to make the final decision that the slip is not generated in the three-slip determination step (S23).

In the case of the present embodiment, the step of determining whether the vehicle input signal is normal may include step S1, but may not include the step S1 of determining whether the vehicle input signal is normal or not. That is, in this case, the vehicle speed calculation method determines whether or not the slip occurrence of the (n + 1) th time point t1 with the nth wheel speed WS0, the n + 1 wheel speed WS1, A slip judgment step (S2) of judging whether the slip is judged; And a vehicle speed calculating step (S3) of calculating a vehicle speed of the (n + 1) th time point (t1) according to a result determined in the slip determining step (S2). After the vehicle speed calculating step (S3) is completed And may be configured to return to the sleep determination step S2.

A: Acceleration S1: Whether the vehicle input signal is normal or not Step
S2: Slip judgment step S3: Vehicle speed calculation step
S21: first slip judgment step S22: second slip judgment step
S23: third slip judgment step S31: first vehicle speed calculation step
S32: Second vehicle speed calculation step S33: Third vehicle speed calculation step
S34: fourth vehicle speed calculation step t0: nth time point
t1: the (n + 1) th time point WS0: the n-th wheel speed
WS1: n + 1 wheel speed WS1max: upper limit of n + 1 wheel speed
WS1min: lower limit of the (n + 1) th wheel speed? WS /? T:

Claims (12)

The wheel speed WS0 of the n-th time point t0, the wheel speed WS1 of the (n + 1) th time point t1 which is later than the n-th point of time t0, (S2) judging whether or not slip of the (n + 1) th time point (t1) has occurred with the acceleration (A) between the +1 time point t1; And
(S3) calculating a vehicle speed of the (n + 1) th time point (t1) according to a result of the determination in the slip determination step (S2)
In the vehicle speed calculation step S3,
When the slip determining step S2 determines that no slip has occurred at the (n + 1) th time point t1, the wheel speed WS1 at the (n + 1) (t1)
The slip determining step S2 determines that a slip has occurred at the (n + 1) th time point t1 and the wheel speed WS1 at the (n + 1) When the wheel speed WS0 and the wheel speed upper limit WS1max of the (n + 1) th time point t1 calculated as the acceleration A between the nth time point t0 and the (n + 1) , The wheel speed upper limit (WS1max) of the (n + 1) th time point (t1) is calculated as the vehicle speed of the (n + 1)
The slip determining step S2 determines that a slip has occurred at the (n + 1) th time point t1 and the wheel speed WS1 at the (n + 1) When the wheel speed WS0 and the wheel speed lower limit WS1min of the (n + 1) th time point t1 calculated as the acceleration A between the nth time point t0 and the (n + 1) , And the wheel speed lower limit (WS1min) of the (n + 1) th time point (t1) is calculated as the vehicle speed of the (n + 1) th time point (t1). The method according to claim 1,
The wheel speed upper limit WS1max of the (n + 1) th time point t1 is set such that the wheel speed WS0 at the nth time point t0 is greater than the wheel speed WS0 at the nth time point t0, Is calculated as the maximum value of the speed range changeable by the step (A)
The wheel speed lower limit WS1min of the (n + 1) th time point t1 is set such that the wheel speed WS0 of the n-th point of time t0 is smaller than the wheel speed WS0 of the n-th point of time t0, Is calculated as the minimum value of the speed range changeable by the step (A). The method according to claim 1,
The vehicle speed calculation step (S3)
When the slip determining step S2 determines that no slip has occurred at the (n + 1) th time point t1, the wheel speed WS1 at the (n + 1) a first vehicle speed computing step (S31) of calculating a vehicle speed of the vehicle;
The slip determining step S2 determines that a slip has occurred at the (n + 1) th time point t1 and the wheel speed WS1 at the (n + 1) 1) th wheel speed (WS1max) of the (n + 1) th time point (t1) is calculated as the vehicle speed of the (n + 1) S32); And
The slip determining step S2 determines that a slip has occurred at the (n + 1) th time point t1 and the wheel speed WS1 at the (n + 1) Th wheel speed lower limit WS1min of the (n + 1) th time point t1 as the vehicle speed of the (n + 1) th time point t1 when it is determined that the wheel speed lower limit WS1min of the S33). ≪ / RTI > The method of claim 3,
The sleep determination step (S2)
The increase rate? WS /? T of the wheel speed between the n-th time point t0 and the (n + 1) th time point t1 is set to a value between the nth acceleration time point t0 and the A) is included in a predetermined range on the basis of the first slip determination step (S21);
The wheel speed WS1 of the (n + 1) th time point t1 is between the wheel speed upper limit WS1max of the (n + 1) th time point t1 and the wheel speed lower limit WS1min of the A second sleep determination step (S22) of determining whether the second sleep determination process is included in the second sleep determination process; And
A third sleep determination step (S23) of determining whether or not sleep occurs at the (n + 1) th time point t1 according to the determination results of the first sleep determination step S21 and the second sleep determination step S22; A method for calculating a vehicle speed for a four-wheel drive vehicle slip control. 5. The method of claim 4,
In the sleep determination step S2,
The increase rate? WS /? T of the wheel speed between the n-th time point t0 and the (n + 1) th time point t1 in the first slip determination step S21 is greater than the nth time point t0, is determined to be not included in a predetermined range based on the acceleration (A) between the (n + 1) th time point t1 and the wheel speed WS1 Is not included between the wheel speed upper limit WS1max of the (n + 1) th time point t1 and the wheel speed lower limit WS1min of the (n + 1) th time point t1, (S23), it is determined that a slip has occurred at the (n + 1) th time point (t1)
The increase rate? WS /? T of the wheel speed between the n-th time point t0 and the (n + 1) th time point t1 in the first slip determination step S21 is greater than the nth time point t0, the wheel speed WS1 of the (n + 1) th time point t1 is determined to be included in a predetermined range based on the acceleration A during the (n + 1) th time point t1, (S23) when it is determined that the first wheel slip speed is included between the wheel speed upper limit WS1max of the (n + 1) th time point t1 and the wheel speed lower limit WS1min of the (n + The slip control device determines that no slip has occurred at the (n + 1) th time point t1 in the slip control of the four-wheel drive vehicle. 5. The method of claim 4,
In the sleep determination step S2,
The increase rate? WS /? T of the wheel speed between the n-th time point t0 and the (n + 1) th time point t1 in the first slip determination step S21 is greater than the nth time point t0, is determined to be not included in a predetermined range based on the acceleration (A) between the (n + 1) th time point t1 or the wheel speed WS1 Is not included between the wheel speed upper limit WS1max of the (n + 1) th time point t1 and the wheel speed lower limit WS1min of the (n + 1) th time point t1, S23, it is determined that a slip has occurred,
The increase rate? WS /? T of the wheel speed between the n-th time point t0 and the (n + 1) th time point t1 in the first slip determination step S21 is greater than the nth time point t0, the wheel speed WS1 of the (n + 1) th time point t1 is determined to be included in a predetermined range based on the acceleration A during the (n + 1) th time point t1, (S23) when it is determined that the first wheel slip speed is included between the wheel speed upper limit WS1max of the (n + 1) th time point t1 and the wheel speed lower limit WS1min of the (n + The slip control device determines that no slip occurs in the slip control of the four-wheel drive vehicle. The method according to claim 6,
The vehicle speed calculation step (S3)
The slip determining step S2 determines that the slip has occurred at the (n + 1) th time point t1 but the wheel speed WS1 at the (n + 1) Th wheel speed WS1 of the (n + 1) th time point t1 is included between the wheel speed upper limit WS1max of the (n + 1) -th time point t1 and the wheel speed lower limit WS1min of the and a fourth vehicle speed calculating step (S34) of calculating the vehicle speed at the (n + 1) th time point (t1). 5. The method of claim 4,
The wheel speed WS0 of the nth time point t0 received from the sensor, the wheel speed WS1 of the (n + 1) th time point t1 and the wheel speed WS1 of the nth time point t0 (S1) for determining whether the acceleration (A) between the (n + 1) th time point and the (n + 1) th time point t1 is included in a predetermined normal range, Way. 9. The method of claim 8,
In the sleep determination step S2,
The wheel speed WS0 of the nth time point t0, the wheel speed WS1 of the (n + 1) th time point t1 and the nth time point t0 of the vehicle input signal are determined in step S1, The first slip determining step S21 and the second slip determining step S22 may be performed in the same manner as the preceding one of the first slip determining step S21 and the second slip determining step S22 when determining that the acceleration A between the (n + 1) th time point t1 is included in the pre- Lt; / RTI >
The wheel speed WS0 of the nth time point t0, the wheel speed WS1 of the (n + 1) th time point t1 and the nth time point t0 of the vehicle input signal are determined in step S1, The controller determines that at least one of the acceleration (A) during the (n + 1) -th time point (t1) is not included in each predetermined normal range and determines that the slip does not occur in the third slip determination step (S23) And the vehicle speed is calculated based on the vehicle speed. 9. The method of claim 8,
And after the vehicle speed calculation step (S3) is completed, return to the step (S1) for determining whether the vehicle input signal is normal. 11. The method according to any one of claims 1 to 10,
The vehicle includes a plurality of wheels,
The wheel speed WS0 at the n-th time point t0 is the rotational speed of the wheel at the n-th time point t0, which is the third among the plurality of wheels,
And the wheel speed WS1 of the (n + 1) th time point t1 is the rotational speed of the wheel whose rotational speed is the third of the plurality of wheels at the (n + 1) th time point t1. Method for calculating vehicle speed for slip control. 11. The method according to any one of claims 1 to 10,
The vehicle includes a longitudinal acceleration sensor for measuring the longitudinal acceleration of the vehicle and a lateral acceleration sensor for measuring the lateral acceleration of the vehicle,
And the acceleration (A) between the n-th time point t0 and the (n + 1) th time point t1 is a vector sum of the longitudinal acceleration and the lateral acceleration.

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