KR20150098787A - Control method for active rear wheel steering apparatus - Google Patents

Abstract

A method of controlling an active rear wheel steering apparatus according to an embodiment of the present invention includes a first step of determining whether a rear wheel steering apparatus is normal or a second step of determining whether the rear wheel steering apparatus is in a normal state A third step of calculating a rear wheel target steering angle when it is determined that the operation of the rear wheel steering device is necessary, a second step of calculating a rear wheel Toyne compensation amount, a second step of calculating a rear wheel target steering angle, A fourth step of calculating a target steering angle for each of the rear wheels based on the one target wheel angle and a fifth step of controlling steering angles of the rear wheel based on the target steering angle for each of the rear wheel targets.

Description

TECHNICAL FIELD [0001] The present invention relates to a control method for an active rear wheel steering apparatus,

[0001] The present invention relates to a control method of an active rear wheel steering apparatus, and more specifically, it relates to a method of controlling an active rear wheel steering apparatus by adjusting a toe-in angle of a rear wheel in a situation requiring braking force compensation, The present invention relates to a control method of an active rear-wheel steering apparatus for improving a rear-

Based on the concept of the four-wheel steering system introduced in the 1980s, many automobile manufacturers have developed and produced a four-wheel steering system based on a rear wheel steering system having a mechanical or hydraulic operating structure since the 1990s. However, And so on.

However, the development of active rear wheel steering system (RWS), which improves the problems of the existing four-wheel steering system, has been developed with the demand for reduction of fuel consumption, expansion of electric vehicles and hybrid electric vehicles, This is the situation that is actively proceeding.

Particularly, in recent years, active rear wheel steering systems including a plurality of actuators capable of independently controlling the toe angle of the rear left / right wheels have been actively studied in order to change and control the steering angle of the rear wheels have.

The four-wheel steering system including the active rear wheel steering system composed of the left and right independent rear wheel toe angle adjusting device improves the maneuverability of the large-sized vehicle by reducing the turning radius at the low-speed turning through the reverse phase control of the rear- In addition, it is possible to improve the safety of the vehicle by reducing the yaw rate and side slip during high-speed turning through the in-phase control of the rear wheel steering system compared to the front wheel steering direction.

Furthermore, it is necessary to improve the braking performance and the turning stability of the vehicle by providing the toe-in angle of the rear wheel suitable for the driving situation.

The following prior art document discloses a technique related to a steering apparatus for adjusting steering lock angle of at least one wheel, particularly a rear wheel, and does not include the technical gist of the present invention.

Korean Patent Publication No. 10-2008-0002924

A control method of an active rear wheel steering apparatus according to an embodiment of the present invention aims to solve the following problems.

An object of the present invention is to provide a control method of an active rear wheel steering apparatus for improving the braking performance and the turning stability of a vehicle by compensating the braking force by adjusting the toe angle of the rear wheel in a situation requiring braking force compensation.

The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

A method of controlling an active rear wheel steering apparatus according to an embodiment of the present invention includes a first step of determining whether a rear wheel steering apparatus is normal or a second step of determining whether the rear wheel steering apparatus is in a normal state A third step of calculating a rear wheel target steering angle when it is determined that the operation of the rear wheel steering device is necessary, a second step of calculating a rear wheel Toyne compensation amount, a second step of calculating a rear wheel target steering angle, A fourth step of calculating a target steering angle for each of the rear wheels based on the one target wheel angle and a fifth step of controlling steering angles of the rear wheel based on the target steering angle for each of the rear wheel targets.

The second step preferably determines whether or not the operation of the rear wheel steering device is necessary based on at least one of the driver's steering angle and the vehicle speed.

The fourth step includes a fourth step of obtaining a rear wheel Toyne compensation amount based on at least one of whether or not the braking system is normally operated, the braking force of the braking system, and whether or not the vehicle is accelerated; And a fourth step of calculating a target steering angle for each of the rear wheels based on at least one of the steering angle and the rear wheel toe-in compensation amount obtained in the step 4-1.

In step 4-1a, it is determined whether the braking system is normal. In step 4-1a, if it is determined that the braking system is normal, A step 4-1c of determining whether the braking force is insufficient if it is determined that the vehicle currently in operation is in braking in the step 4-1b; And a 4-1d step of calculating a compensation amount.

If it is determined in step 4-1a that the brake system is not normal, it is determined in step 4-1e whether the current vehicle is accelerating. In step 4-1e, it is determined that the current vehicle is not accelerating And calculating the toe-in compensation amount when it is determined that the toe-in compensation amount is not satisfied.

And a sixth step of detecting a change amount of a rear wheel steering angle by controlling the steering angle of each of the rear wheels in the fifth step, wherein the fourth step further comprises: detecting a rear wheel target steering angle, a rear wheel Toyne compensation amount, It is preferable to calculate the target steering angle for each of the rear wheel wheels.

And a seventh step of prohibiting operation of the rear wheel steering device and lighting a warning lamp when it is determined that the rear wheel steering apparatus is not normal in the first step.

The control method of the active rear wheel steering apparatus according to an embodiment of the present invention uses an active rear wheel steering apparatus capable of controlling the toe angle so as to discriminate whether the brake system is normal, whether it is braked or not and whether the braking system is abnormal, Determining the acceleration or non-acceleration, determining whether or not to perform the rear wheel toe-in compensation mode, and computing or setting the toe angle compensation amount to compensate the Toe angle compensation amount to the rear wheel target steering angle to calculate and control the target steering angle of each rear wheel, The performance and the turning stability can be improved.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an in-vehicle arrangement of a rear wheel steering apparatus for implementing a control method of an active rear wheel steering apparatus according to an embodiment of the present invention; FIG.
FIG. 2 is a block diagram illustrating a rear wheel steering apparatus for implementing a control method of an active rear wheel steering apparatus according to an embodiment of the present invention and related configurations.
FIG. 3 is a flowchart illustrating a control method of an active rear wheel steering apparatus according to an embodiment of the present invention in a time-series manner.
FIG. 4 is a flow chart illustrating the steps of obtaining the rear-wheel towin compensation amount and calculating the target steering angle for each of the rear wheels in the method of controlling the active rear wheel steering apparatus according to the embodiment of the present invention.
FIG. 5 is a flowchart illustrating a step of acquiring a rear-wheel train to-be-reward amount in a method of controlling an active rear wheel steering apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

FIG. 1 is a view showing an arrangement of a rear wheel steering apparatus in a vehicle for implementing a control method of an active rear wheel steering apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of an active rear wheel steering apparatus according to an embodiment of the present invention. Fig. 2 is a block diagram illustrating a rear wheel steering apparatus for implementing a control method of the present invention;

As shown in FIG. 1, the rear wheel steering apparatus for realizing the control method of the active rear wheel steering apparatus according to an embodiment of the present invention is generally disposed on the left rear wheel and the right rear wheel of the vehicle, respectively.

The configuration of the active rear wheel steering apparatus 100 will be described with reference to FIG.

Each of the active rear wheel steering units includes actuators 110 and 140 for moving the left and right rear wheels, actuators 110 and 140, and actuators 110 and 140 for driving the left and right rear wheels. And an electric control unit (ECU) 120 and 160 for controlling the driving of the actuator 110 and 140. The actuator 110 and 140 and the electronic control unit 120 and 160 are usually provided with a hard wire (H / Wire) Lt; / RTI >

The electronic control units 120 and 160 calculate the driving amounts of the actuators 110 and 140 based on the values output from the brake device 200 or the front wheel steering device 500 Further comprising a rear wheel steering sensor (130, 150) for sensing the position or angle of the left and right rear wheels so that the value detected by the rear wheel steering sensors (130, 150) 120, and 160 so as to calculate the amount of drive of the actuators 110 and 140.

In particular, the output value from the wheel speed sensor 300 and the brake light switch or the brake pedal travel sensor can be used as the output value from the brake device 200, and the output value from the front wheel steering sensor 500 is output from the front wheel steering sensor 600 ) Can be used.

Communication between the braking device 200 and the front wheel steering device 500 and the rear wheel steering device 100 is preferably performed through CAN (Controller Area Network) communication.

Hereinafter, a method of controlling the active rear wheel steering apparatus according to an embodiment of the present invention will be described with reference to FIGS. 3 and 5. FIG.

FIG. 3 is a flowchart illustrating a method of controlling an active rear wheel steering apparatus according to an embodiment of the present invention in a time-series manner, and FIG. 4 is a flowchart illustrating a method of controlling a rear wheel toe in an active rear wheel steering apparatus according to an embodiment of the present invention. FIG. 5 is a flow chart illustrating a step of acquiring the rear-wheel-to-rear-wheel-side compensation amount among the control methods of the active rear-wheel steering apparatus according to the embodiment of the present invention.

As shown in FIG. 3, the control method of the active rear wheel steering apparatus according to an embodiment of the present invention includes a first step S100 of determining whether the rear wheel steering apparatus is normal, whether the state of the rear wheel steering apparatus is required A third step S300 for calculating a rear wheel steering angle, a fourth step S400 for calculating a rear wheel Toyne compensation amount, a target steering angle for each rear wheel, and a steering angle for each wheel And a fifth step S500.

The first step S100 is a step of determining whether the rear wheel steering apparatus operates normally or not. Specifically, the first step S100 is a step of determining whether a connection portion connected by a hard wire is disconnected or short-circuited among the respective configurations inside the rear wheel steering apparatus, It is possible to determine whether or not the rear wheel steering apparatus is operating normally based on whether or not communication is normally performed with the system hardware, whether or not the system hardware is operating normally, whether or not the software for implementing the electronic control apparatus is abnormal, and the like.

If it is determined that the rear wheel steering apparatus is normally operated in the first step S100, the second step S200 is performed. If it is determined that the rear wheel steering apparatus is not normally operated, the operation of the rear wheel steering apparatus is prohibited The seventh step S700 of turning on the warning light is performed.

The second step S200 is a step of determining whether or not the rear wheel steering apparatus is in a required state when it is determined that the rear wheel steering apparatus operates normally in the first step S100 as described above, The steering angle, or the speed of the vehicle being driven.

If it is determined in the second step S200 that the operation of the rear wheel steering apparatus is unnecessary, the operation of the rear wheel steering apparatus is canceled or the rear wheel steering angle is set to zero. If it is determined that the operation of the rear wheel steering apparatus is necessary, A third step S300 of calculating a target steering angle is performed.

The target steering angle of the rear wheels is preferably calculated on the basis of an equivalent bicycle model of the automobile.

After the rear wheel target steering angle is calculated in the third step S300, a fourth step S400 of obtaining the rear wheel Toyne compensation amount and calculating a target steering angle for each rear wheel is performed.

The fourth step S400 includes a fourth step S410 of obtaining a rear wheel Toyne compensation amount based on at least one of the normal operation of the brake system, the braking force of the brake system and the acceleration of the vehicle, (S420) of calculating a target steering angle for each of the rear wheels based on at least one of the target steering angle and the rear wheel target steering angle and the rear wheel Toyne compensation amount.

In particular, the fourth step S410 of obtaining the rear wheel toein compensation amount may be embodied as a plurality of steps. Hereinafter, the step of acquiring the rear wheel Toyne compensation amount will be described in detail with reference to FIG.

First, in step 4-1a (S411), it is determined whether or not the brake system is normal. The determination is made using the communication state of the brake system, the fault / warning lamp state of the brake system, and the like.

If it is determined in step 4-1a (S411) that the brake system is normal, a step 4-1b (S412) of determining whether the vehicle currently in operation is in braking is performed. This step 412b is performed by a brake light switch, A brake pedal travel sensor, a master cylinder pressure sensor, and the like.

 If it is determined in step 4-1b that the vehicle currently in operation is in the braking state, a step 4-1c (S413) of determining whether or not the braking force is insufficient is performed, and the output value and the change rate of the brake pedal travel sensor, The output value and the rate of change of the pressure sensor, and whether or not the situation is a panic brake or a brake assist state.

If it is determined that the braking force is insufficient in step 4-1c (S413), the 4-1d step (S414) of calculating the rear wheel Toyne compensation amount is performed, and this rear wheel Toyne compensation amount is set to a function set through experiments, The rear wheel Toyne compensation amount is determined by a function formed by a correlation formed between the output value of the pedal travel sensor or the master cylinder pressure sensor and the rear wheel Toyne compensation amount or by applying a preset first set value.

If it is determined that the brake system is not normal in the step 4-1a (S411), a step 4-1e (S415) of judging whether or not the vehicle currently in operation is accelerating is performed, and the accelerator pedal Based on the output value of the sensor (Accelerator Pedal Sensor).

If it is determined in the step 4-1e (S415) that the vehicle currently being driven is accelerating, the rear wheel Toyne compensation mode is canceled or the rear wheel Toyne compensation value is set to 0, and if it is determined that the vehicle currently being driven is not accelerating 4-1f step S416 of calculating the toein compensation amount is performed, and the toein compensation amount may be determined by applying a preset second set value different from the first set value.

If it is determined in step 4-1b (S412) that the vehicle currently in operation is not braking, or if it is determined in step 4-1c (S413) that the braking force is not insufficient, step 4-1e (step S415) The compensation mode for the rear wheel toy is canceled or the compensation value for the rear wheel toy is set to zero as in the case where it is determined that the vehicle currently being driven is accelerating.

When the rear wheel toein compensation amount is calculated or determined, it is determined that the braking system is in normal operation, the braking force is insufficient in the current braking state of the vehicle, and the brake system is not operating normally, It can be said that this is not the case.

After the compensation amount is calculated or determined in the above two cases, the target steering angle for each wheel is calculated based on the rear wheel target steering angle calculated in the third step S300 and the rear wheel Toyne compensation amount obtained in the fourth step S410 Step 4-2 (S420) is performed. Specifically, the target steering angles for the rear wheels may be calculated by the following equations (1) and (2).

( Equation  One)

Rear Left Goal Target = Rear Wheel Target Steering Angle - (Rear Wheel Toein Compensation / 2)

( Equation  2)

Rear Right Targeting = Rear Wheel Target Steering Angle + (Rear Wheel Toein Compensation / 2)

In step S420, if the target steering angle is determined for each of the rear wheels, a fifth step S500 of controlling the steering angles of the rear wheels based on the target steering angles is performed. Specifically, by controlling the actuator of the rear wheel steering apparatus, .

In addition, a sixth step (S500) of detecting the change amount of the steering angle of the rear wheel may be further included, and this may be detected through a position sensor or a tire angle sensor for each wheel.

The detected amount of change in the rear wheel steering angle is determined together with the target steering angle and the amount of rear wheel toe in determining the target steering angle for each wheel of the rear wheel, .

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.

100: rear wheel steering device
110, 140: Actuator
120, 160: Electronic control unit
130. 150: rear wheel steering sensor
200: Brake device
300: Wheel speed sensor
400: Brake light switch / brake pedal Travel sensor
500: front wheel steering device
600: Front wheel steering sensor

Claims (7)

A first step (S100) of determining whether the rear wheel steering apparatus is normal or not;
A second step (S200) of determining whether the operation of the rear wheel steering apparatus is necessary if the rear wheel steering apparatus is determined to be normal;
A third step (S300) of calculating a rear wheel target steering angle when it is determined that the operation of the rear wheel steering apparatus is necessary;
A fourth step (S400) of obtaining a rear wheel Toyne compensation amount and computing a target steering angle for each rear wheel wheel based on at least one of the rear wheel target steering angle and the rear wheel toein compensation amount; And
A fifth step (S500) of controlling the steering angles of the rear wheels based on the target angles of the rear wheels;
And a control unit for controlling the rear wheels.
The method according to claim 1,
In the second step S200,
And determines whether or not the operation of the rear wheel steering apparatus is necessary based on at least one of a steering angle of the driver and a vehicle speed of the vehicle.
The method according to claim 1,
In the fourth step S400,
A fourth step (S410) of obtaining a rear wheel Toyne compensation amount based on at least one of whether the brake system is normally operated, the braking force of the brake system, and whether the vehicle is accelerated; And
A fourth step (S420) of calculating a target steering angle for each of the rear wheels based on the rear wheel target steering angle calculated in the third step and the rear wheel Toyne compensation amount obtained in the fourth step;
And a control unit for controlling the rear wheels.
The method of claim 3,
In the fourth step S410,
A step 4-1a (S411) of judging whether or not the brake system is normal;
If it is determined that the brake system is normal in step 4-1a (S411), step 4-1b (S412) of determining whether the vehicle currently in operation is in braking operation;
If it is determined in the step 4-1b (S412) that the currently running vehicle is in braking, it is determined whether or not the braking force is insufficient (S413); And
A 4-1d step (S414) of calculating a rear wheel Toyne compensation amount when it is determined that the braking force is insufficient in the 4-1c step (S413);
And a control unit for controlling the rear wheels.
5. The method of claim 4,
If the brake system is judged to be abnormal in the step 4-1a (S411), it is determined whether or not the current vehicle is accelerating (S415); And
4-1f step S416 of calculating a toe-in compensation amount when it is determined in the step 4-1e (S415) that the currently running vehicle is not accelerating;
Further comprising the steps of:
The method according to claim 1,
A sixth step (S600) of detecting a change in the rear wheel steering angle by controlling the steering angle of the rear wheel in the fifth step (S500);
Further comprising:
The fourth step S400 calculates a target steering angle for each of the rear wheels based on at least one of the rear wheel target steering angle, the rear wheel Toyne compensation amount, and the rear wheel steering angle change amount.
The method according to claim 1,
A seventh step (S700) of prohibiting operation of the rear wheel steering apparatus and lighting a warning lamp when it is determined that the rear wheel steering apparatus is not normal in the first step (S100);
Further comprising the steps of:

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