KR20180094653A - Steering control system in a vehicle and method thereof - Google Patents

Abstract

The present invention provides an automotive steering control system and a control method thereof. The automotive steering control system according to an embodiment of the present invention comprises: a sensor unit for receiving an automobile speed, a steering angle, and external temperature information; and a control unit which adds a vibration current to a motor of a steering apparatus when a rack thrust estimated based on the measured steering angle is greater than a reference value when an automobile is traveling in a low temperature environment.

Description

TECHNICAL FIELD [0001] The present invention relates to a steering control system for a vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a steering control system for a vehicle and a control method thereof, and more particularly, to a steering control system and a control method thereof for preventing a steering from freezing due to a sudden drop in external temperature.

2. Description of the Related Art [0002] Generally, as automobile technology has developed remarkably, techniques for developing various conveniences have been steadily developed for the convenience of the driver.

Particularly, the power steering or power assist steering apparatus assists the steering wheel operating force of the driver by using the booster when the driver operates the steering wheel of the automobile, thereby facilitating the steering direction of the vehicle with a smaller force And the like. Such a power steering device is roughly classified into hydraulic power steering (HPS) and electric power steering (EPS).

In the hydraulic power steering, when the hydraulic pump connected to the rotation shaft of the engine feeds the operating oil to the operating cylinder connected to the rack bar, the piston of the operating cylinder supplied with the operating oil assists the steering operation force, It is a device that enables steering operation with small force.

On the other hand, electric power steering includes a motor and an electronic control unit (ECU) in the rack bar or column instead of the hydraulic pump and the actuating cylinder, and it is a device that assists the operation force by the power of the motor.

Such a rack-driven electric power steering system includes a rack bar extending in the lateral direction of the automobile and having a rack gear on one side thereof, a pinion shaft having a pinion gear engaged with the rack gear, a ball nut engaged with the outer screw groove A belt-type transmission device for connecting the ball nut and the motor shaft, and a motor.

The pinion shaft is connected to the steering wheel through the steering shaft, and the rack bar having the outer circumferential screw groove formed on one side of the outer circumferential surface is embedded in the rack housing.

The rack driving type electric power steering includes a rack bar having an outer circumferential screw groove on an outer circumferential surface thereof, a ball nut having an intermediate path through which the ball circulates, a ball moving in contact with an outer circumferential screw groove of the rack bar and a middle path, And an end cap attached to an end of the cap.

In such a rack-driven electric power steering, the ball slides the rack bar by the movement of the cloud while contacting the outer screw groove of the rack bar and the inner screw groove of the ball nut.

The pinion shaft and the torque sensor are coupled to the rack housing, the connector of the wire harness inserted through one side of the rack housing is coupled to the torque sensor, and the bearing is coupled to the pinion shaft.

When the pinion shaft and the torque sensor are coupled to the rack housing, the rack housing cover having the sealing member coupled to the upper side is coupled to the rack housing by the fastening member to complete the assembly.

On the other hand, in the case of the rack-driven electric power steering, when the outside temperature suddenly drops in the low-temperature environment, the mechanical parts are damaged and water is introduced, so that the rack bar equipped with the rack gear and the pinion gear engaged with the rack gear, There is a problem that a failure situation occurs.

Japanese Patent Application Laid-Open No. 10-2015-0083185

Therefore, in the embodiment of the present invention, it is determined in advance whether or not the electric power steering is frozen to prevent a situation in which steering is impossible.

Further, the embodiment of the present invention is intended to prevent the situation where the electric power steering is frozen by thawing to prevent the steering from being impossible.

According to an aspect of the present invention, there is provided a steering apparatus for a vehicle, comprising: a communication unit for receiving a vehicle speed, a steering angle, and outside temperature information; and a control unit for, when the rack thrust estimated based on the steering angle measured when the vehicle is traveling in a low- And a control unit for adding a vibration current to the motor of the vehicle.

Also, the controller may determine that the vehicle is traveling in a low-temperature environment when the external temperature is less than the first threshold value and the vehicle speed is equal to or greater than the second threshold value.

The controller may estimate the rack thrust if the steering angle is less than a third threshold and the calculated steering angle velocity is less than a fourth threshold.

In addition, the controller may block the added vibration current after a predetermined time elapses.

Also, the reference value may increase linearly with the vehicle speed.

According to another aspect of the present invention, there is provided a method for controlling a vehicle in a low temperature environment, the method comprising: measuring a speed of the vehicle, a steering angle and an external temperature; Estimating a rack thrust based on the time-of-hour steering angle; And adding a vibration current to the motor of the steering apparatus if the estimated rack thrust is equal to or greater than a reference value; . ≪ / RTI >

Determining whether the vehicle is traveling in a low-temperature environment based on the vehicle speed and the external temperature information; determining whether the external temperature is less than a first threshold value; And determining whether the speed of the vehicle is equal to or greater than a second threshold value.

Also, the rack thrust can be estimated when the steering angle is smaller than the third threshold value and the calculated steering angle velocity is smaller than the fourth threshold value.

The method may further include the step of adding a vibration current to the motor of the steering apparatus when the estimated rack thrust is equal to or greater than a reference value, and blocking the added vibration current after a lapse of a predetermined time.

Also, the reference value may increase linearly with the vehicle speed.

Therefore, the embodiment of the present invention can determine in advance whether or not the electric power steering is frozen to prevent a situation in which steering is impossible.

In addition, the embodiment of the present invention can prevent the situation where the steering is not possible by thawing the freeze of the electric power steering.

1 is a partial cross-sectional view schematically showing an electric power steering operated by a steering control system according to an embodiment of the present invention.
2 is a block diagram of a steering system according to an embodiment of the present invention.
3 is a schematic view showing a steering control method according to an embodiment of the present invention.
4 is a simplified flowchart illustrating a steering control method according to an embodiment of the present invention.
5 is a detailed flowchart of a steering control method according to an embodiment of the present invention.
6 is a detailed flowchart showing control termination of the steering control method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

FIG. 1 is a partial cross-sectional view schematically showing an electric power steering operated by a steering control system according to an embodiment of the present invention, and FIG. 2 is a block diagram of a steering system according to the present invention.

In the case of a vehicle equipped with a steering system according to the present invention, a vehicle is usually equipped with an engine control system, a brake-by-wire, an AVN apparatus (Audio Video Navigation), a transmission control system (TMS) A control system 170, an input / output control system, and other vehicle sensors.

However, such an electronic device is only a part of the electronic device included in the vehicle 1, and the vehicle 1 may be provided with more various electronic devices.

In addition, the various electronic devices 100 included in the vehicle 1 can communicate with each other through the vehicle communication network NT. The Vehicle Communication Network (NT) may be a Media Oriented Systems Transport (MOST) having a communication speed of up to 24.5 Mbps (Mega-bits per second), a FlexRay having a communication speed of up to 10 Mbps, a CAN (Controller Area Network) having a communication speed of 1 Mbps to 1 Mbps, and a LIN (Local Interconnect Network) having a communication speed of 20 kbps. Such a vehicle communication network NT can employ not only a single communication protocol such as a mast, a player, a can, a lean, but also a plurality of communication protocols.

At least one or more vehicle sensors included in the vehicle may include an acceleration sensor 196, a yaw rate sensor 197, a steering angle sensor 198, a speed sensor 199, and the like to sense driving information of the vehicle.

The acceleration sensor 196 measures the acceleration of the vehicle and may include a lateral acceleration sensor (not shown) and an acceleration sensor (not shown).

The yaw rate sensor 197 can be installed on each wheel of the vehicle and can detect the yaw rate value in real time.

The steering angle sensor 198 measures the steering angle. Mounted on the lower end of the steering wheel (not shown), and can detect the steering speed, the steering direction, and the steering angle of the steering wheel.

The speed sensor 199 can be installed inside the wheel of the vehicle to detect the rotational speed of the vehicle wheel.

The temperature sensor 200 can measure the temperature of the outside of the vehicle during running.

At this time, the sensor values measured from at least one or more sensors 196 to 200 included in the vehicle 1 may be transmitted to the steering control system 170 according to the present invention and used to perform the steering control.

Finally, the steering control system 170 according to the present invention determines whether or not there is freezing in the steering apparatus based on the sensor value obtained from the other vehicle sensor 195, and controls the freezing of the freezing steering apparatus to thaw.

At this time, the steering control system 170 according to the present invention can eliminate freezing in the electric power steering shown in FIG.

Such electric power steering is provided with a rack bar 1000 extending in the lateral direction of the automobile 1 and having a rack gear on one side of its outer circumference to provide a driving force to the wheel W of the vehicle and a pinion shaft 210, A ball nut 300 which engages with the outer circumferential screw groove 101 via a ball and a ball nut 300 which engages with the ball nut 300 and the motor shaft, And includes a belt-type power transmission apparatus 400 and a motor 500 which are connected to each other.

The rack bar 100 having the pinion shaft 210 connected to the steering wheel 202 through the steering shaft 201 and the outer circumferential screw groove 101 having a predetermined length formed on one side of the outer circumferential surface is installed in the rack housing 110 do.

The belt-type transmission apparatus 400 includes a belt connecting the motor shaft and the ball nut 300, and is configured to receive steering assist force generated by the motor 500 in proportion to the steering torque applied to the steering wheel 202 And transmits it to the rack bar 100 through the nut 300.

At this time, the steering control system 170 according to the present invention determines that freezing occurs in the electric power steering and thaws the freezing steering device.

 2, the steering control system 170 according to an embodiment of the present invention includes a first sensor unit 8, a second sensor unit 9, an electronic control unit 20, A driving unit 30 and a warning unit 40.

The steering control system 170 according to the present invention is connected to the vehicle communication network NT from the first sensor unit 8 and the second sensor unit 9 to detect the steering angle of the vehicle 1 And transmits communication signals to various electronic devices 100 in the vehicle 1 through the vehicle communication network NT. Here, the communication signal means a signal transmitted / received through the vehicle communication network NT. Therefore, the steering control system 170 transmits the sensor value acquired from the first sensor unit 8 and the second sensor unit 9 to the electronic control unit 20. [

      First, the first sensor unit 8 includes a motor current sensor 7, a torque sensor 6, and an angular velocity sensor 5. Specifically, the motor current sensor 7 senses the amount of current flowing in the motor 500 shown in FIG. 1, and can sense whether the current flows normally in the motor 500 and the amount of current flowing.

      Next, the torque sensor 6 senses the steering torque amount applied to the steering wheel 202. [

      Finally, the angular velocity sensor 5 can sense the angular velocity applied to the steering wheel 202. [

       Thereafter, the motor current value sensed by the motor current sensor 7, the torque value of the steering wheel 202 acquired from the torque sensor 6, and the angular velocity value of the steering wheel 202 acquired from the angular velocity sensor 5, And transmitted to the rack force estimation unit 22 of the control unit 20. [

Next, the vehicle sensor included in the second sensor unit 9 may be an acceleration sensor 196, a yaw rate sensor 197, a steering angle sensor 198, a speed sensor 199, and a temperature sensor 200.

Accordingly, the steering control system 170 receives the acceleration, the yaw rate, the steering angle, the speed, and the external temperature of the vehicle measured from various sensors included in the second sensor unit 9 of the vehicle.

The electronic control unit 20 collectively controls the steering control system 170 according to the present invention.

Specifically, the electronic control unit 20 is configured to estimate the rack force of the electric power steering device based on the motor current value, the torque sensor value, and the angular velocity value acquired from the first sensor portion 8, A rack freezing sensor 21 for determining whether freezing occurs in the rack based on the rack force estimated value estimated by the rack force estimating unit 22 and the various sensor values acquired through the second sensor unit 9 And a controller 23 for eliminating freezing when ice occurs.

Further, although not shown, the steering control system 170 according to the present invention includes a memory for storing various data necessary for performing the operation of the electronic control unit 20. [

However, the electronic control unit 20 estimates the rack force based on the value obtained from the first sensor unit 8 before determining whether or not the freezing occurs.

Specifically, the rack force estimating section 22 estimates the rack force based on the motor current value, the torque sensor value, and the angular velocity sensor value.

Next, the electronic control unit 20 determines whether freezing occurs on the side of the rack bar 1000 inside the electric power steering based on the sensor value received from the vehicle sensor (20). Specifically, the rack force estimation unit 22 ) And the various sensor values acquired by the second sensor unit 9, it is possible to determine whether or not the rack freezing has occurred. More specifically, the determination of whether or not the rack is freeze can be performed in the rack freeze detection unit 21 in the electronic control unit 20. [

In the case where rack freezing occurs, for example, in the case where the vehicle 1 is lifted up in an area with a high cold winter altitude, when moisture flows into the electric power steering and freezes, even though the driver operates the steering wheel , And the handle is fixed.

In addition, a case where the temperature changes suddenly as the vehicle 1 in the room moves out of the room and the moisture flows into the electric power steering and is frozen.

Accordingly, the electronic control unit 20 controls the step S1 of determining whether or not freezing has occurred in the electric power steering, and the step S2 of controlling the drive unit 30 to secure additional current for freezing the motor 500, And a control step S2 for calculating a signal.

The rack freeze detection unit 21 in the electronic control unit 20 detects the vehicle speed measured from the speed sensor 199 of the other vehicle sensor 195 and the external temperature secured from the temperature sensor 200 and the steering angle sensor 198, (S11) of judging whether the vehicle 1 is in a traveling state in a low-temperature environment based on the steering angle secured by the rack force estimating unit 22 and whether the freezing occurs in the power steering apparatus based on the rack thrust estimated by the rack- (Step S12).

More specifically, the step S11 of determining whether the vehicle is in a running state in a low-temperature environment in the freezing state of the rack 21 is performed when the vehicle speed measured by the speed sensor 199 exceeds a first threshold value, ) Is in a running state at a predetermined speed or more.

The step S11 of determining whether the vehicle is in a running state in a low temperature environment in the freezing detection unit 21 of the rack determines whether the external temperature measured by the temperature sensor 200 is lower than a second threshold, Check whether the vehicle is running in a low temperature environment.

In addition, when the inclination (decrease) of the external temperature measured by the temperature sensor 200 is greater than a third threshold value, which is a preset threshold, the rack freeze detection unit 21 detects a sudden change in the external temperature You can also check.

The step S11 of determining whether the vehicle is in a running state in the low temperature environment in the freezing condition detecting unit 21 is performed when the steering angle measured by the steering angle sensor 198 is smaller than a third threshold value set in advance and the steering angle sensor 198 ) Is smaller than a fourth threshold value, which is a preset threshold value, whether or not the steering angle velocity estimated based on the measured steering angle is smaller than a predetermined threshold value.

At this time, if the vehicle speed exceeds the first threshold value, the external temperature is smaller than the second threshold value, the steering angle is less than the third threshold value, and the steering angle velocity is less than the fourth threshold value The main processor 21 can determine that the vehicle 1 is in a running state in a low temperature environment.

When the vehicle speed exceeds the first threshold value and the slope (decrease) of the external temperature is greater than a third threshold value, which is a preset threshold value, and the steering angle speed is less than the fourth threshold value, The main processor 21 can judge that the vehicle 1 is running when the vehicle 1 is suddenly changed in the external temperature.

At this time, the rack freezing detection unit 21 in the electronic control unit 20 additionally detects a rack force (hereinafter, referred to as a rack thrust) of the vehicle 1 estimated by the rack force estimation unit 22. [ It is possible to detect whether or not the rack is freeze.

Specifically, the rack force field refers to a force generated between the ground and the wheel W when the driver rotates the steering wheel 202. As described above, the sensor included in the first sensor portion 8 Lt; / RTI >

Accordingly, when the obtained rack thrust is greater than a preset threshold value, the determination unit 22 can determine that freezing has occurred in the steering device.

At this time, the fifth threshold value set in advance varies linearly according to the vehicle speed.

The determination unit 22 included in the electronic control unit 22 of the steering control system 170 according to the present invention determines the vehicle speed measured from the speed sensor 199 and the outside temperature secured from the temperature sensor 200, A step S11 of judging whether the vehicle 1 is in a traveling state in a low temperature environment based on the steering angle secured by the sensor 198 or a step S12 of estimating a rack thrust to determine whether freezing occurs in the power steering apparatus So that it is judged that the freezing is required for a certain period of time after the corresponding determination steps S11 and S12 are held.

Accordingly, when the steering control system 170 of the vehicle according to the present invention determines that the freezing of the power steering apparatus has occurred, the control unit 23 causes the driving unit 30 to flow an additional current to eliminate the freezing through vibration of the power steering apparatus .

That is, the control unit 23 in the electronic control unit 20 applies an additional current to the motor 500 to generate vibration in the electric power steering apparatus.

Specifically, as shown in Fig. 3, by applying an additional current that vibrates to the target current at the time point t1 determined as freezing, the icing inside the electric power steering apparatus can be eliminated.

The configuration and the control method of the steering control system 170 according to the present invention have been described above.

4 and 6 are flowcharts of a control method of the steering control system 170 according to the present invention. FIG. 4 shows a simplified flowchart of a control method in the electronic control unit 20, The control method of the electronic control unit 20 of the steering control system according to the invention is determined to be freezing in the steering apparatus, and the control method after the freezing in the steering apparatus is determined.

4, the steering control system 170 according to the present invention acquires a vehicle sensor value from at least one or more sensors included in the vehicle (S1000).

Then, the steering control system 170 estimates the rack thrust based on various sensor values of the acquired vehicle, particularly, the sensor value included in the first base sensor unit 8 (S2000). At this time, when the rack thrust estimated by the electronic control unit 20 in the steering control system 170 exceeds the preset threshold value (YES in S3000), it is determined that freezing in the steering apparatus has occurred (S4000).

Therefore, the electronic control unit 20 applies an additional motor current to the motor to solve the freezing in the steering apparatus (S5000).

5 and 6 are flowcharts specifically showing a method of estimating the rack thrust from the sensors of the vehicle in the steering control system 170, a method of determining freezing and a method of applying an additional current.

First, as shown in FIG. 5, the vehicle speed, the external temperature, and the steering angle of the vehicle 1 equipped with the steering control system 170 according to the present invention are measured (S10 to S30).

That is, the vehicle speed can be measured through the speed sensor 199, the external temperature can be measured through the temperature sensor 200, and the steering angle can be measured through the steering angle sensor 198.

At this time, the measured sensor value is received through the communication unit 10 included in the steering control system 170.

Next, based on the received sensor value, the steering control system 170 exceeds the first threshold value preset in the vehicle speed (YES in S40), the external temperature is lower than the preset second threshold value (S50 The rack thrust is estimated (S70) when the steering angle is lower than a preset third threshold and the steering angle velocity is lower than a preset fourth threshold (S60).

The rack thrust estimated by the electronic control unit 20 refers to a force generated between the ground and the wheel W when the driver rotates the steering wheel 202. The rack thrust is a force 500, the motor current value, the steering angle speed, and the like.

Therefore, when the estimated rack thrust is larger than the preset threshold value (YES in S80), the electronic control unit 20 can determine that freezing has occurred in the steering apparatus (S90).

At this time, the fifth threshold value set in advance varies linearly according to the vehicle speed.

Accordingly, when it is determined that the freezing of the power steering apparatus has occurred, the steering control system 170 of the vehicle according to the present invention, as shown in FIG. 6, flows an additional current to the driving unit 30 to vibrate the power steering apparatus Eliminates freezing.

That is, when the electronic control unit 20 determines that it is freezing, the main processor 21, as shown in FIG. 4, applies an additional electric current that vibrates to the target current at the time point t1 determined as freezing, Freezing of the inside of the apparatus can be eliminated.

Accordingly, the electronic control unit 20 transmits the vibration to the power steering device as the additional current is applied to the motor 500 (S110). If it is determined that the freezing is canceled after a predetermined time elapses (YES in S120) (S130).

At this time, it can be estimated that the electronic control unit 20 determines that the freezing in the power steering apparatus is canceled, but it is not limited to this.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein; It will be understood that various modifications may be made without departing from the spirit and scope of the invention.

1: vehicle
170: Steering control system

Claims (10)

A sensor unit for acquiring a vehicle speed, a steering angle, and external temperature information;
And a controller for adding a vibration current to the motor of the steering device when the rack thrust estimated based on the measured steering angle is equal to or greater than a reference value when the vehicle is traveling in a low temperature environment. The method according to claim 1,
Wherein the control unit determines that the vehicle is traveling in a low temperature environment when the external temperature is less than the first threshold value and the vehicle speed is equal to or greater than the second threshold value. 3. The method of claim 2,
Wherein the controller estimates the rack thrust when the steering angle is smaller than a third threshold value and the obtained steering angle velocity is less than a fourth threshold value. The method of claim 3,
Wherein the control unit interrupts the added vibration current when a predetermined time elapses. 5. The method of claim 4,
Wherein the reference value linearly increases in accordance with the vehicle speed. Measuring a speed, a steering angle and an external temperature of the vehicle;
Determining whether the vehicle is traveling in a low-temperature environment based on the measured vehicle speed and the external temperature information;
Estimating a rack thrust based on a steering angle when traveling in a low temperature environment; And
Adding a vibration current to the motor of the steering apparatus if the estimated rack thrust is equal to or greater than a reference value; . The method according to claim 6,
Determining whether the vehicle is traveling in a low temperature environment based on the vehicle speed and the external temperature information;
Determining whether the external temperature is less than a first threshold; And
And determining whether the speed of the vehicle is equal to or greater than a second threshold value. 8. The method of claim 7,
Wherein the rack thrust estimates that the steering angle is smaller than a third threshold value and the calculated steering angle velocity is less than a fourth threshold value. 9. The method of claim 8,
Adding a vibration current to the motor of the steering apparatus if the estimated rack thrust is equal to or greater than a reference value;
And blocking the added vibration current when a predetermined time elapses. 10. The method of claim 9,
Wherein the reference value linearly increases in accordance with the vehicle speed.

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