KR20180049576A - Traction control system and method of controlling the same - Google Patents

Abstract

The present invention relates to a traction control system and a method for controlling the same, which can essentially prevent slip of a rear wheel by controlling torque of the rear wheel before a slip occurs on the rear wheel side in a hybrid vehicle equipped with an in-wheel motor in a front wheel. According to the present invention, a traction control system includes a force estimator for estimating the longitudinal force of a tire; a slip estimator for estimating the slip of the tire; and track controller for calculating an optimum wheel slip point by using the longitudinal force of the tire estimated by the force estimator and the slip of the tire estimated by the slip estimator and for controlling an in-wheel motor of a front wheel by using the calculated optimal slip point.

Description

TECHNICAL FIELD [0001] The present invention relates to a traction control system and a control method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction control system and a control method thereof. More particularly, the present invention relates to a traction control system and a control method thereof, The present invention relates to a traction control system and a control method thereof.

Generally, as an apparatus for improving stability during running of a vehicle, there are an anti-lock brake system (ABS) for preventing slip during braking, a Traction Control System (TCS) for preventing slip during sudden acceleration, (Electronic Stability Control), which is a stability system that improves driving stability by stably maintaining the stability.

On the other hand, in the conventional TCS, the wheel slip of the wheel is prevented by applying the brake torque by hydraulic pressure to the corresponding wheel by using the ESC when the wheel slip is detected in the corresponding wheel as each wheel is operated individually .

However, in the conventional TCS, since the generation time of the hydraulic pressure for applying the brake torque is constant, relatively large lag and delay occur, and since the TCS can be operated after the wheel slip has already advanced considerably, There is a disadvantage that the wheel slip can not be effectively controlled. That is, since the TCS is operated after the wheel slip of each wheel occurs and the wheel slip proceeds to a considerable level, it is difficult to effectively control the wheel slip with respect to the corresponding wheel.

In addition, since the conventional TCS controls each wheel independently, and the TCS is controlled after the wheel slip of each wheel is detected, the control performance of the TCS is relatively low. Therefore, There is a growing need for integration.

SUMMARY OF THE INVENTION The present invention provides a traction control system and a control method thereof that can improve TCS control performance of an entire vehicle by performing integrated TCS control for front wheels and rear wheels, There is a purpose.

According to an aspect of the present invention, there is provided a track control system for controlling a slip of a hybrid vehicle having an in-wheel motor installed in a front wheel of the vehicle,

A force estimator for estimating a longitudinal force of the tire;

A slip estimator for estimating a wheel slip of the tire; And

An optimum wheel slip point is calculated using the longitudinal force of the tire estimated by the force estimator and the wheel slip estimated by the slip estimator, and the calculated optimal slip point is used And a track control controller for controlling the operation of the in-wheel motor of the front wheels.

Wherein the track control controller generates map data by mapping the correlation between the longitudinal force of the tire estimated by the force estimator and the wheel slip estimated by the slip estimator, May be configured to yield an optimum wheel slip point.

The track control controller may adjust the driving torque of the front wheel in-wheel motor to oscillate the wheel slip of the front wheel to a predetermined range when the current slip of the tire is equal to or greater than a preset maximum slip value.

Another aspect of the present invention is a control method of a track control system for controlling a slip of a hybrid vehicle provided with an in-wheel motor in a front wheel of the vehicle,

Estimates the longitudinal force of the tire and the wheel slip of the tire,

Generates map data indicating the relationship between the estimated longitudinal force of the tire and the wheel slip of the tire,

Calculates an optimum wheel slip point based on the map data,

Controls the wheel slip of the front wheel to fluctuate when the current wheel slip of the tire is equal to or greater than a set maximum slip value,

The road surface friction coefficient is calculated using the maximum longitudinal force and the vertical load of the front wheel during the control while varying the wheel slip of the front wheel,

It is possible to calculate the maximum torque value that the rear wheel of the vehicle can generate using the calculated road surface friction coefficient.

The map data is generated as a curve of a certain shape, and an optimum wheel slip point can be calculated if the curve of the map data is a normal shape having an inflection point.

And a point where the tangent slope is '0' in the curve of the map data can be set as the optimum wheel slip point.

If the current wheel slip of the tire is equal to or greater than the preset maximum slip value, the drive torque of the front wheels may be controlled to control the wheel slip of the front wheels to fluctuate.

The drive torque of the rear wheels can be controlled by the calculated road surface friction coefficient and the maximum torque value.

According to the present invention, it is possible to improve the TCS control performance of the entire vehicle by performing integrated TCS control on the front wheels and the rear wheels.

In particular, the present invention uses a quick response of an in-wheel motor in a hybrid vehicle equipped with an in-wheel motor in a front wheel so as not to generate a relatively large wheel slip in the front wheel, And the torque of the rear wheel is controlled in accordance with the calculated maximum torque value, so that the occurrence of wheel slip in the rear wheel can be prevented or minimized in advance.

1 is a view illustrating a drive system of a hybrid vehicle to which a traction control system according to an embodiment of the present invention is applied.
2 is a conceptual diagram illustrating a process of calculating a wheel slip curve of a traction control system according to an embodiment of the present invention.
3 is a flowchart illustrating a control method of a traction control system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the sake of convenience, the size, line thickness, and the like of the components shown in the drawings referenced in the description of the present invention may be exaggerated somewhat. The terms used in the description of the present invention are defined in consideration of the functions of the present invention, and thus may be changed depending on the user, the intention of the operator, customs, and the like. Therefore, the definition of this term should be based on the contents of this specification as a whole.

1 shows a hybrid vehicle in which an in-wheel motor is mounted. In the hybrid vehicle shown in Fig. 1, a motor-generator 13 is disposed between an engine 11 and a transmission 12, Generator (13) to the transmission (12) side.

A pair of front wheels 1 are disposed on both left and right sides of the engine 11 and an in-wheel motor 3 can be installed in the front wheel 1. [ The front wheel 1 can be independently driven by the in-wheel motor 3. A pair of regenerative braking systems 17 may be provided on both sides of the engine 11.

A rear drive shaft 14 is connected to the transmission 12 and a differential device 15 may be installed at a rear end of the rear drive shaft 14. [ A pair of rear wheels (2) are connected to the differential device (15) via a pair of rear axles (16).

A decoupler 18 may be provided between the differential device 15 and the rear axle 16 and the differential device 15 and the rear axle 16 may be detachably connected by the decoupler 18 .

According to the embodiment of the present invention, a traction control controller 20 can be connected to the in-wheel motor 3, and the in-wheel motor 3 can be controlled by the track control controller 20 have. In addition, the track control controller 20 can be connected to the engine controller, and the track control controller 20 can control the drive torque of the rear wheels 2 via the engine controller.

Accordingly, the track control system according to the embodiment of the present invention controls the in-wheel motor 3 so that relatively large wheel slip does not occur in the front wheel 1 by using the quick response of the in-wheel motor 3, And the torque of the rear wheel 2 is controlled in accordance with the calculated maximum torque value. The wheel slip occurrence in the rear wheel 2 is not known .

2, a track control system according to an embodiment of the present invention includes a force estimator 21 for estimating a longitudinal force Fx of a tire, a slip estimator 22 for estimating a wheel slip of the tire , a slip estimator, and an optimum wheel slip point using the longitudinal force of the tire estimated by the force estimator 21 and the wheel slip estimated by the slip estimator 22 And a track control controller 20 for controlling the operation of the in-wheel motor 3 of the front wheel 1 by using the calculated optimum slip point.

The force estimator 21 and the slip estimator 22 output various data 28 such as a longitudinal acceleration, a lateral acceleration, a yaw rate, a steering angle, a wheel speed, and the like through an ECU, an EMS, Input can be received. Using the data 28 thus inputted, the force estimator 21 can estimate the longitudinal force F _x of the tire, and the slip estimator 22 can estimate the wheel slip (?) Of the tire.

According to an embodiment of the present invention, the slip estimator 22 may be a tire slip estimator, and the tire slip estimator may estimate the wheel slip (?) Of the tire using the various data 28 input And may be configured to operate directly.

According to another embodiment of the present invention, the sleep estimator 22 may be a vehicle speed estimator. For example, since the vehicle speed estimated by the vehicle speed estimator is in a predetermined functional relationship with the wheel slip (?) Of the tire, the track control controller 20 calculates the wheel slip (?) Of the tire by using the vehicle speed estimated by the vehicle speed estimator ). Accordingly, the slip estimator 22 according to another embodiment of the present invention may be a vehicle speed estimator in place of the tire slip estimator.

The track control controller 20 displays the correlation between the estimated longitudinal force F _x of the tire in the force estimator 21 and the wheel slip of the tire estimated by the slip estimator 22, the map data 25 can be generated by mapping the map data 25 to an optimum wheel slip point (? _opt ) based on the generated map data 25.

When the acceleration is advanced by the driver's will and the current slip of the tire is equal to or greater than the set maximum slip value? _Max , the track control controller 20 controls the front wheel 1, particularly the in- The wheel slip of the front wheel 1 can be oscillated with a certain fluctuation range (see arrow a in Fig. 2) by adjusting the drive torque of the front wheel 3.

For example, close to the front wheel (1) of wheel slip is optimal wheel slip points (λ _opt) at least when the in-wheel wheel slip optimal wheel slip points (λ _opt) of the front wheel (1) by reducing the drive torque of the motor 3 is And when the wheel slip of the front wheel 1 becomes equal to or less than the optimal wheel slip point λ _opt , the driving torque of the in-wheel motor 3 is increased so that the wheel slip of the front wheel 1 becomes the optimum wheel slip point λ _opt ). For example, the track control controller 20 controls the wheel slip of the front wheel 1 to fluctuate to a constant fluctuation width (a) in the vicinity of the optimal wheel slip point so that the wheel slip is prevented from being relatively large in the front wheel 1 can do.

The track control controller 20 uses the maximum longitudinal force F _{x_max} corresponding to the optimal wheel slip point calculated from the map data 25 and the vertical load F _{z_front} of the front wheel 1 to calculate the road friction coefficient And the maximum torque value that the rear wheels can generate can be calculated by using the calculated road surface friction coefficient. The track control controller 20 transmits the calculated maximum torque value to an engine controller (not shown) or the like so that the engine controller (not shown) can control the drive torque of the rear wheel 2 to be the maximum torque value .

3 is a diagram illustrating a control method of a track control system according to an embodiment of the present invention.

The track control system TCS can be activated (S1) when the vehicle is accelerated by the driver's will.

The longitudinal force F _x of the tire is estimated by a force estimator 21 and the slip estimator 22 estimates the wheel slip λ of the tire.

When the estimated longitudinal force F _x of the tire and the wheel slip λ of the tire are input to the track control controller 20, the track control controller 20 calculates the longitudinal force F _x Map data 25 having a curve of a certain type indicating the relationship between wheel slip (?) Is generated (S3).

)는 변곡점을 기준으로 양의 접선기울기와 음의 접선기울기를 가질 수 있고, 이에 변곡점에서의 접선기울기는 '0'이 될 수 있다(

).The map data 25 illustrated in FIG. 2 shows that as the longitudinal force F _x of the tire and the wheel slip of the tire increase, the longitudinal force F _x of the tire increases and then decreases as it passes the inflection point . In the graph of FIG. 2, the longitudinal force F _x and the tangential slope of the wheel slip (

) Can have a positive tangent slope and a negative tangent slope with respect to the inflection point, and the tangent slope at the inflection point can be zero

).

) 지를 판단한다(S4). 이는 맵 데이터(25)의 곡선이 변곡점을 가진 정상적인 형태인지를 판단하기 위함이다. When the tangential slope of the longitudinal force (F _x ) and wheel slip (?) Has a negative slope (

(S4). This is to judge whether the curve of the map data 25 is a normal shape having an inflection point.

If it is determined in step S4 that the tangential slope of the longitudinal force F _x and the wheel slip? Has a negative slope, the map data 25 generated in step S3 can be recognized as having a normal inflection point, The point at which the tangential slope of the longitudinal force F _x and the wheel slip λ is '0' is set as the optimum wheel slip point λ _opt as shown in the graph of FIG. 2 (S5). If it is determined in step S4 that the tangential slope of the longitudinal force F _x and the wheel slip λ does not have a negative slope, the map data 25 generated in step S3 is recognized as an abnormal one having no inflection point And the map data 25 can be regenerated by returning to the step S2.

Thereafter, it is determined whether or not the current acceleration of the vehicle is continued by the driver's will and the current wheel slip is equal to or greater than the preset maximum value (S6).

If it is determined in step S6 that the current wheel slip is equal to or greater than the set maximum value? _Max , the track control controller 20 controls the wheel slip of the front wheel 1 to vary by adjusting the drive torque of the front wheel 1 (S7).

Here, the track control controller 20 can oscillate the wheel slip of the front wheel 1 to a constant range (see arrow a in Fig. 2) by adjusting the drive torque of the in-wheel motor 3 in the front wheel 1 have.

For example, close to the front wheel (1) of wheel slip is optimal wheel slip points (λ _opt) at least when the in-wheel wheel slip optimal wheel slip points (λ _opt) of the front wheel (1) by reducing the drive torque of the motor 3 is And when the wheel slip of the front wheel 1 becomes equal to or less than the optimal wheel slip point λ _opt , the driving torque of the in-wheel motor 3 is increased so that the wheel slip of the front wheel 1 becomes the optimum wheel slip point λ _opt ). For example, the track control controller 20 controls the wheel slip of the front wheel 1 to fluctuate to a certain fluctuation width (a) in the vicinity of the optimum wheel slip point (? _Opt ) so that a relatively large wheel slip Can be controlled so as not to occur. Here, the fluctuation width (a) can be changed according to the state of the road surface while the vehicle is running, and the fluctuation width (a) can be set so as to correspond to the change of the road surface friction coefficient calculated in step S8. For example, the fluctuation range (a) may be between 0.1 and 0.2.

On the other hand, if it is determined in step S6 that the current wheel slip is less than or equal to the preset maximum value (? _Max ), the process returns to step S4 to reset the optimum wheel slip? _Opt .

The road surface friction coefficient by Equation 1 below was provided in step S7 to control while changing the wheel slip of the front wheel (1) using the maximum longitudinal force (F _{x_max)} and vertical load (F _{z_front)} of the front wheel (μ (S8).

The maximum torque value? _Rear that the rear wheel 2 can generate using the road surface friction coefficient? Calculated in the step S8 is calculated by the following formula (2) (S9).

Here, r _e is the effective radius of the wheel of the rear wheel 2, and F _{z_rear} is the vertical load of the rear wheel 2.

The track control controller 20 transmits the maximum torque value calculated by Equation (2) to an engine controller (not shown) or the like and the engine controller (not shown) calculates the maximum torque value of the rear wheels 2 It is possible to control to be the torque value? _Rear . Thus, the rear wheel 2 can be controlled by the road surface friction coefficient and the maximum torque value calculated by the in-wheel motor 3 of the front wheel 1, so that the occurrence of wheel slip in the rear wheel 2 can be prevented Or the occurrence of wheel slip can be minimized.

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, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .

1: front wheel
2: rear wheel
3: In-wheel motor
11: Engine
12: Transmission
13: Motor-generator
14: rear drive shaft
15: Differential
16: rear axle
17: Regenerative braking system
18: decoupler
20: Track control controller
21: force estimator
22: Slip estimator

Claims (8)

A track control system for controlling the slip of a hybrid vehicle equipped with an in-wheel motor in a front wheel of the vehicle,
A force estimator for estimating a longitudinal force of the tire;
A slip estimator for estimating a wheel slip of the tire; And
An optimum wheel slip point is calculated using the longitudinal force of the tire estimated by the force estimator and the wheel slip estimated by the slip estimator, and the calculated optimal slip point is used And a track control controller for controlling the operation of the in-wheel motor of the front wheels. The method according to claim 1,
Wherein the track control controller generates map data by mapping the correlation between the longitudinal force of the tire estimated by the force estimator and the wheel slip estimated by the slip estimator, A track control system configured to produce an optimum wheel slip point. The method of claim 2,
Wherein the track control controller oscillates the wheel slip of the front wheel by a predetermined amount by adjusting the driving torque of the front wheel of the front wheel when the current slip of the tire is equal to or greater than a preset maximum slip value. A control method for a track control system for controlling a slip of a hybrid vehicle equipped with an in-wheel motor in a front wheel of the vehicle,
Estimates the longitudinal force of the tire and the wheel slip of the tire,
Generates map data indicating the relationship between the estimated longitudinal force of the tire and the wheel slip of the tire,
Calculates an optimum wheel slip point based on the map data,
Controls the wheel slip of the front wheel to fluctuate when the current wheel slip of the tire is equal to or greater than a set maximum slip value,
The road surface friction coefficient is calculated using the maximum longitudinal force and the vertical load of the front wheel during the control while varying the wheel slip of the front wheel,
And calculating a maximum torque value that the rear wheel of the vehicle can generate using the calculated road surface friction coefficient. The method of claim 4,
Wherein the map data is generated as a curved line of a predetermined shape, and an optimal wheel slip point is calculated when the curve of the map data is a normal shape having an inflection point. The method of claim 5,
And setting a point where a tangent slope is '0' in the curve of the map data as an optimum wheel slip point. The method of claim 4,
And controlling the drive torque of the front wheels to change the wheel slip of the front wheels when the current wheel slip of the tire is equal to or greater than a set maximum slip value. The method of claim 4,
And controlling the driving torque of the rear wheels based on the calculated road surface friction coefficient and the maximum torque value.

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