KR100751216B1 - Electronic stability system for vehicle - Google Patents

Abstract

The present invention relates to a stability control system of a vehicle, and more particularly, to a stability control system of a vehicle for improving stability of a vehicle during braking operation on an asymmetric road surface using a plurality of sensors for detecting movement information of the vehicle. will be.

Determining whether the current road surface is a split road surface; determining whether a spin out phenomenon occurs on a split road surface; performing spin out braking control when a spin out phenomenon occurs; Computing the difference of the rotation moment generated in both wheels of the front wheel, and performing the braking control according to the calculated difference of the rotation moment.

Asymmetrical Road, Spin Out

Description

Electronic stability system for vehicle

1 is a block diagram showing the configuration of a vehicle stability system of the present invention.

2 is a flow chart illustrating a control flow of the present invention.

3 is a view showing a driving state on a split road surface of a vehicle configured in the vehicle stability control system of the present invention.

4 is a diagram illustrating a driving state on a split road surface of a conventional vehicle.

* Description of the symbols for the main parts of the drawings *

10: measuring unit 20: control unit

21: pressure estimator 22: yaw rate estimator

23: yaw rate error calculation unit 24: spin-out determination unit

25 pressure controller 30 pressure modulator

The present invention relates to a stability control system of a vehicle, and more particularly, to a stability control system of a vehicle for improving stability of a vehicle during braking operation on an asymmetric road surface using a plurality of sensors for detecting movement information of the vehicle. will be.

In general, the anti-lock brake system (hereinafter referred to as ABS) is to prevent the wheel from locking by appropriately adjusting the braking pressure applied to the wheel according to the slip ratio calculated from the wheel speed. The TCS (hereinafter referred to as TCS) is to control the driving force of the engine to prevent excessive slippage during sudden start or acceleration of the vehicle.

The anti-lock brake system (ABS) and traction control system (TCS) can perform well when the vehicle is driving on a straight road, but when steered on a curve road, the understeer is excessively inclined outward. Can occur and, conversely, over steer can occur that is excessively inward.

Therefore, there is a demand for a vehicle stability system (hereinafter referred to as an electronic stability program ESP) to stably control a vehicle's posture under any circumstances in which the vehicle travels, that is, to prevent steering loss of the vehicle. For example, in a situation where an under steer is pushed out of a desired driving trajectory when turning, a braking force is applied to the rear wheels to prevent the vehicle from being pushed outward and the turning speed of the vehicle is increased. In a situation where an excessively large oversteer is inclined inward on a desired driving trajectory, a braking force is required to the front wheels.

In order to control vehicle stability during turning, the performance of the system is determined by accurately predicting the turning speed of the driver's desired vehicle and by applying the appropriate braking pressure to the front and rear wheels to drive the vehicle according to the predicted turning speed. do.

In addition, in controlling the stability of the vehicle, the performance of the above-described ABS and TCS should not be impaired. On the contrary, the stability of the vehicle is not adversely affected by the ABS and the TCS. Therefore, in order to control the safety of the vehicle appropriately in the state of movement of the vehicle, it is desirable to focus on cooperative control in conjunction with the existing ABS and TCS.

In the conventional vehicle stability system as described above, one side is a high friction road surface based on an asymmetric road surface, that is, a left and right side road, and one side is a setting implemented in the existing ABS in performing the control during braking operation on the low friction road surface. If a slip error occurs, appropriate braking control is performed. This is a control method that supports the driver's steering to enable stable braking only when the vehicle is traveling in a straight line, and when an obstacle such as a vehicle exists in front of the driver, In case of steep steering and proper steering operation, the vehicle is trying to drive on the high friction road due to the rotational moment and the driver tries to steer on the opposite side, but the rotation moment to the high friction road surface acts to spin out the vehicle. out) phenomenon occurs that occurs.

Accordingly, the present invention provides a stability control system of a vehicle for improving the stability of the vehicle during braking operation on an asymmetrical road surface by using a plurality of sensors for detecting the motion information of the vehicle to solve the above problems. There is.

The present invention for solving the above object,

Determining whether the current road surface is a split road surface; determining whether a spin out phenomenon occurs on a split road surface; performing spin out braking control when a spin out phenomenon occurs; Computing the difference of the rotation moment generated in both wheels of the front wheel, and performing the braking control according to the calculated difference of the rotation moment.

The determining of whether the spin-out phenomenon occurs is determined as a spin-out phenomenon when the error between the estimated yaw rate and the measured yaw rate exceeds a preset value, the measured yaw rate exceeds a preset value, and the lateral acceleration exceeds a preset value. It is characterized by.

The spin-out braking control increases the braking slip of the outer wheel of the front wheel based on the generated rotation moment, sets the braking pressure increase rate, and sets the braking slip of the inner wheel of the rear wheel smaller based on the generated rotation moment. It is characterized in that it is performed.

The step of performing braking control according to the difference of the rotation moment, if the difference of the rotation moment is greater than the first predetermined value, the braking pressure is reduced,

When the value is smaller than the first set value and larger than the second preset value, the rate of increase of the braking pressure is decreased.                     

If less than the second set value is carried out to increase the rate of increase of the braking pressure.

The present invention for performing the above operation,

In a vehicle configured with a plurality of sensors for detecting various movement information,

And a controller for inputting motion information of the vehicle sensed by the plurality of sensors to calculate a rotation moment, and outputting a braking control signal of the vehicle using the calculated rotation moment value when the split road surface is driven.

The control unit may include a pressure estimating unit estimating a braking pressure applied to each wheel by a pressure value of the master cylinder sensed by the sensor, a yaw rate estimating unit estimating a yaw rate from a steering angle of a handle detected by the sensor; A yaw rate error calculating unit for calculating an error between the estimated yaw rate output from the yaw rate estimating unit and the measured yaw rate measured from the sensor, each yaw rate detected from the sensor, the lateral acceleration and the yaw rate A spinout determination unit for outputting a control signal by judging whether a spinout phenomenon occurs by inputting a yaw rate error value of the error calculation unit; and outputting a spinout braking control signal when the control signal is output from the spinout determination unit. If not, the brake control signal is input by inputting the pressure value of the pressure estimation unit and the error value of the yaw rate error calculator. It is configured to include an output control unit for pressure.

Hereinafter, the detailed configuration and operation of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram showing the configuration of the vehicle stability system of the present invention, Figure 2 is a flow chart showing the control flow of the present invention, Figure 3 is a split road surface of the vehicle configured in the vehicle stability control system of the present invention 4 is a diagram illustrating a driving state, and FIG. 4 is a diagram illustrating a driving state on a split road surface of a conventional vehicle.

First, the configuration will be described with reference to FIG. 1.

The present invention comprises a measurement unit 10, the control unit 20, the pressure modulator 30.

The measuring unit 10 includes a pressure sensor 11 for measuring a discharge pressure of a master cylinder (not shown), a steering angle sensor 12 for measuring a steering angle of a steering wheel by a driver, and a yaw rate generated when the vehicle travels. It consists of a yaw rate sensor 13 for measuring the lateral acceleration sensor 14 for measuring the acceleration acting on the side of the vehicle.

The controller 20 may include a pressure estimator 21 estimating a braking pressure applied to each wheel by a pressure value of the master cylinder sensed by the pressure sensor 11, and a handle detected by the steering angle sensor 12. Computing the error between the yaw rate estimator 22 for estimating the yaw rate from the steering angle and the estimated yaw rate output from the yaw rate estimator 22 and the measured yaw rate measured from the yaw rate sensor 13 Yaw rate error calculation unit 23, the yaw rate sensor 13, the yaw rate detected from the lateral acceleration sensor 14, the lateral acceleration and yaw rate error of the yaw rate error calculation unit 23 The spinout determining unit 24 outputs a control signal by determining whether a spinout phenomenon occurs by inputting a value, and outputs a spinout braking control signal when the control signal is output from the spinout determining unit 24. If not Pressure weight groups by entering the error value of the pressure value and the yaw rate error calculating unit 23 of section 21 is configured to include a pressure controller 25 which outputs a braking control signal.

Control process of the present invention configured as described above is shown in Figure 2,

Determining whether the current road surface is a split road surface; determining whether a spin out phenomenon occurs on a split road surface; performing spin out braking control when a spin out phenomenon occurs; Computing the difference of the rotation moment generated in both wheels of the front wheel, and performing the braking control according to the calculated difference of the rotation moment.

The detailed operation is as follows.

If the driver operates a brake pedal (not shown) for braking while the vehicle is driving on a split road, that is, one side is a low friction road and one side is a low friction road, the braking force of the high friction road is greater than that of the low friction road. As a result, the rotation moment is generated on the high friction road surface, and the driver attempts to steer in the opposite direction in which the driver's rotation moment acts, but the spin out occurs due to the rotation moment on the high friction road surface.

The yaw rate estimator 22 of the controller 20 of FIG. 1 estimates the yaw rate of the current vehicle by using the steering angle of the steering wheel sensed by the steering angle sensor 12, and the yaw rate error calculator 23 The error between the yaw rate measured by the rate sensor 13 and the yaw rate estimated by the yaw rate estimating unit 22 is calculated.

The spinout determination unit 24 inputs the error value of the yaw rate error calculating unit 23, the measured yaw rate value of the yaw rate sensor 13, and the lateral acceleration value of the lateral acceleration sensor 14. It is determined whether or not it occurs.

That is, when each yaw rate error value, the measured yaw rate value, and the lateral acceleration value exceed each preset value, it is determined as spin out.

However, if any one of the yaw rate error value, the measured yaw rate value, and the lateral acceleration value is less than the respective set value, it is recognized that spin-out phenomenon does not occur.

When the spin out determination unit 24 outputs the spin out generation signal, the pressure controller 25 outputs a signal to the pressure modulator 30 to perform the braking force control corresponding to the spin out by inputting it. The braking slip of the outer front wheel is increased based on the rotation moment, the braking pressure rise rate is set high, and the braking slip of the inner rear wheel is set small based on the generated rotation moment.

That is, since the rotation moment acts as a high friction road surface on the asymmetric road surface with reference to FIG. 4, the braking slip of the front wheel left wheel is increased, the braking pressure rise is set high, and the braking slip of the rear wheel right wheel is set small. It is to be output to the pressure modulator (30).

When the signal indicating that the spinout phenomenon has not occurred is output from the spinout determiner 24, the pressure controller 25 performs general braking control on the split road surface.

First, the rotation moment error between the front wheel left wheel and the right wheel is calculated.

The rotation moment error is calculated by the following equation.                     

[Equation]

Where Mdiff is the difference between the moment of rotation on the low friction road wheel and the moment of rotation on the high friction road wheel, Pfl is the brake pressure on the left wheel of the front wheel, and Pfr is the brake pressure on the right wheel of the front wheel. Value, ψdesired is estimated yaw rate, ψmeasured is measured yaw rate, α is pressure gain and β is yaw rate gain.)

That is, the rotation moment error Mdiff is calculated using the error between the braking pressure value applied to the left wheel and the braking pressure value applied to the right wheel, and the error between the measured yaw rate and the estimated yaw rate.

When the rotation moment error Mdiff is calculated as in the above equation, the pressure controller 25 outputs a braking control signal to the calculated value. As shown in FIG. The braking control signal is output using the two set values A2, that is, two threshold values.

The first set value A1 is a threshold hold value calculated through actual vehicle experiments in consideration of the starting point of spinout, and the second set value A2 is a threshold hold calculated through actual vehicle experiments in consideration of braking force loss. Value.

 If the rotation moment error Mdiff is greater than the first set value A1, the braking pressure is decreased. If the rotation moment error Mdiff is greater than the first set value A1, the braking pressure decreases when the rotation moment error Mdiff is smaller than the first set value. If it is smaller than 2 set value A2, it is set to increase the rate of increase of braking pressure and output.

That is, the mean of the rotation moment error Mdiff is greater than the first set value A1 means that the spinout is more likely to occur, and the mean of the rotation moment error Mdiff is smaller than the second set value A2. This means that too much braking force is applied for postural stability.

As described above, in the present invention, the driver's safety by providing a control method and a control device for improving the stability of the vehicle during braking operation on an asymmetrical road surface by using a plurality of sensors for detecting the motion information of the vehicle when the split road surface is driven. This ensures the reliability of the brake system, thereby improving the reliability of the braking system.

Claims (13)

In a vehicle configured with a plurality of sensors for detecting various movement information, A pressure estimating unit estimating a braking pressure applied to each wheel by the pressure value of the master cylinder sensed by the sensor; A yaw rate estimator for estimating a yaw rate from a steering angle of a handle sensed by the sensor; A yaw rate error calculating unit for calculating an error between the estimated yaw rate output from the yaw rate estimating unit and the measured yaw rate measured from the sensor; When the error value of the yaw rate error calculation unit, the measured yaw rate measured by the sensor, and the lateral acceleration measured by the sensor exceeds a predetermined value, respectively, the spinout determination unit for judging a spinout phenomenon and outputting a control signal; , When the control signal is output from the spin out determination unit outputs a spin out braking control signal, otherwise inputs the pressure value of the pressure estimation and the error value of the yaw rate error calculation unit is composed of a braking pressure control unit for outputting a braking control signal Vehicle stability control system comprising a control unit. delete delete The method of claim 1, The spin-out braking control signal of the braking pressure controller increases the braking slip of the outer wheel of the front wheel based on the direction of rotational moment generated, sets the braking pressure increase rate, and sets the inner wheel of the rear wheel based on the generated rotational moment. The braking slip of the vehicle stability control system, characterized in that the output is set. The method of claim 1, The braking control signal when the spin-out phenomenon of the braking pressure controller does not occur is a first set value in which a difference between a rotation moment generated on the wheel of the low friction road surface of the front wheel and a rotation moment generated on the wheel of the high friction road surface is preset. When the pressure is greater than the first set value, the braking pressure is decreased, and when the value is greater than the second preset value, the rate of increase of the braking pressure is decreased. A stability control system for a vehicle. The method of claim 5, The first set value is a threshold hold value set through actual vehicle experiment in consideration of the starting point of spin out, and the second set value is a threshold hold value set through real vehicle experiment in consideration of braking force loss. Control system. The method of claim 5, The difference between the rotation moment generated on the wheel of the low friction road surface on the front wheel side and the rotation moment generated on the wheel of the high friction road surface is calculated by the following equation. [Equation]

Where Mdiff is the difference between the moment of rotation on the low friction road wheel and the moment of rotation on the high friction road wheel, Pfl is the brake pressure on the left wheel of the front wheel, and Pfr is the brake pressure on the right wheel of the front wheel. Value, ψdesired is estimated yaw rate, ψmeasured is measured yaw rate, α is pressure gain and β is yaw rate gain.) In the vehicle stability control system, Determining whether the current road surface is a split road surface, Comparing the error value, the measured yaw rate, and the lateral acceleration of the estimated yaw rate and the measured yaw rate with each other on the split road surface and determining the spinout phenomenon if all of them are exceeded; Performing spin out braking control when a spin out phenomenon occurs; Calculating a difference between rotation moments occurring at both wheels of the front wheels if the spinout phenomenon does not occur in the step; And performing a braking control according to the difference of the calculated rotation moments. delete The method of claim 8, The spin-out braking control increases the braking slip of the outer wheel of the front wheel based on the generated rotation moment, sets the braking pressure increase rate, and sets the braking slip of the inner wheel of the rear wheel smaller based on the generated rotation moment. Vehicle stability control system, characterized in that carried out by. The method of claim 8, The step of performing braking control according to the difference of the rotation moment, if the difference of the rotation moment is greater than the first predetermined value, the braking pressure is reduced, When the value is smaller than the first set value and larger than the second preset value, the rate of increase of the braking pressure is decreased. If the value is less than the second set value, the stability control system of the vehicle, characterized in that performed in the step of increasing the rate of increase. The method of claim 11, The first set value is a threshold hold value set through actual vehicle experiment in consideration of the starting point of spin out, and the second set value is a threshold hold value set through real vehicle experiment in consideration of braking force loss. Control system. The method of claim 8, Computing the difference of the rotation moment is a stability control system of a vehicle, characterized in that achieved by the following equation. [Equation]

Where Mdiff is the difference between the moment of rotation on the low friction road wheel and the moment of rotation on the high friction road wheel, Pfl is the brake pressure on the left wheel of the front wheel, and Pfr is the brake pressure on the right wheel of the front wheel. Value, ψdesired is estimated yaw rate, ψmeasured is measured yaw rate, α is pressure gain and β is yaw rate gain.)

Images