KR20150066699A

KR20150066699A - Apparatus and method for controlling motor driven power steering system

Info

Publication number: KR20150066699A
Application number: KR1020130152040A
Authority: KR
Inventors: 김용규; 강진욱; 백수호
Original assignee: 현대오트론 주식회사
Priority date: 2013-12-09
Filing date: 2013-12-09
Publication date: 2015-06-17
Also published as: KR101544884B1

Abstract

The present invention relates to an MDPS (Motor Driven Power Steering) system and an MDPS control method, and more particularly, to a method of controlling an MDPS system using an angle sensor even when a torque sensor constituting an MDPS system does not operate normally .
To this end, the present invention comprises: determining whether the torque sensor is operating normally; Determining whether the angle sensor is operating normally if the torque sensor is malfunctioning; Switching to an MDPS temporary control mode using the angle sensor when the angle sensor operates normally; Rotating the steering wheel clockwise or counterclockwise by a predetermined reference angle; Measuring an operation angle of the driver in accordance with the steering wheel operation corresponding to the rotation of the steering wheel by the reference angle through the angle sensor; Comparing the steering wheel operating angle of the driver measured from the angle sensor with predetermined reference angle; And providing power to the motor for driving the steering wheel based on the comparison result, when the operating angle and the reference angle are different from each other, determining that there is steering intention of the driver.

Description

Technical Field [0001] The present invention relates to an MDPS system and a control method thereof,

The present invention relates to a MDPS (Motor Driven Power Steering) system and an MDPS control method, and more particularly, to a method for smoothly controlling an MDPS system even when a torque sensor constituting an MDPS system fails.

A power steering apparatus (power steering apparatus) of a vehicle is a device for reducing the steering wheel operating force of a driver.

Among them, the MDPS device is a device that utilizes the force of a motor instead of the hydraulic pressure, and is light in weight compared to a conventional hydraulic power steering device, occupies a small space, and does not require oil change, .

The MDPS system may be mounted on an arm connecting a steering gear box and a knuckle to a motor, or mounted on a steering column (connected to a steering wheel), but the MDPS system senses the rotation of the steering wheel, The basic operation for determining the power supply amount of the motor in accordance with the vehicle speed is the same.

Basically, the MDPS system includes a motor, a steering gear box, a torque sensor, and an MDPS ECU. The MDPS ECU senses the turning force of the steering wheel through the torque sensor and controls the torque of the steering wheel by applying current to the motor according to the vehicle speed. The steering gear box receives the driving force through the steering shaft, A rod, a tie rod, and a knuckle arm).

3 is a diagram showing a general MDPS configuration.

As shown in the drawing, the MDPS includes a motor unit 5 having a speed reducer composed of a worm-shaft and a worm wheel in a steering column 2 having a steering wheel 1 and a gear box 3 And a tilt-telescopic unit 6 for moving the steering column 2 in a tilt or telescopic manner is mounted. The MDPS is provided with a MDPS-ECU 4 for controlling the motor unit 5 and a torque sensor 7 for detecting the steering degree according to the steering of the steering wheel 1 and providing it to the MDPS- do. Accordingly, in the MDPS, when the motor unit 5 is driven under the control of the MDPS-ECU 4 that senses the steering input by the torque sensor 7, the motor power is converted to the output torque through the speed reducer, .

The torque sensor 7 typically uses an optical sensor. For example, it is possible to measure the steering angle of the steering wheel and the steering speed by laying the light receiving portion on the torsion bar rotating together with the steering wheel 1 and laying the light emitting portion on the fixed point.

Korean Unexamined Patent Publication No. 2012-0051846 (entitled "Torque Control Method of MDPS System") is a method of controlling a torque of an MDPS system, comprising the steps of: sensing torque according to rotation of a steering wheel; Sensing a load applied to a front wheel of the vehicle; And applying a current to the motor in accordance with a torque and a vehicle speed of the steering wheel based on a predetermined data value. When the load applied to the front wheel exceeds a predetermined reference value, the amount of current applied to the motor is increased, And the amount of current applied to the motor is reduced when the applied load falls below a predetermined reference value.

Korean Patent Laid-Open No. 2008-0086193 entitled "MDPS Torque Sensor Fault Detection Method", MDPS (Motor Driven Power Steering) is a method of determining a failure of a torque sensor, Measuring a steering torque signal and measuring a steering torque signal of the second vehicle through a second MDPS torque sensor; Summing the measured steering torque signals of the first and second vehicles; Determining whether an absolute value of a sum of the steering torque signals of the first and second vehicles is within a predetermined range; Judging that both of the first and second MDPS torque sensors are normal if the absolute value of the sum of the steering torque signals of the first and second vehicles is within a certain range; Calculating a slope of the steering torque signal of the first vehicle and the second vehicle at a predetermined time using the measured steering torque signals of the first and second vehicles; Calculating an absolute value of the measured steering torque signal of the first vehicle by using the calculated slope of the steering torque signal of the first vehicle and a predetermined allowable range with respect to the slope within a predetermined allowable range with respect to the slope ; Determining a failure of the first MDPS torque sensor if the measured absolute value of the steering torque signal of the first vehicle is not within a predetermined allowable range with respect to the slope; Determining whether the absolute value of the steering torque signal of the second vehicle is within a predetermined permissible range with respect to the slope by using the calculated slope of the steering torque signal of the second vehicle and a predetermined allowable range with respect to the slope Wow; And determining the failure of the second MDPS torque sensor if the measured absolute value of the steering torque signal of the second vehicle is not within a predetermined allowable range with respect to the slope .

However, the above-described conventional technology shows a method of controlling the torque of the MDPS by using the torque by the torque sensor and a method of judging the failure of the MDPS torque sensor. However, in the case of the control of the MDPS even when the torque sensor fails, . Therefore, there is a need for a way to control the MDPS even if the torque sensor fails.

The present invention proposes a method for temporarily controlling the MDPS even when the torque sensor constituting the MDPS system fails.

In addition, the present invention proposes a method that can cope with an emergency when the torque sensor of the MDPS malfunctions by temporarily controlling the angle sensor.

According to an aspect of the present invention, there is provided a method of controlling an MDPS (Motor Driven Power Steering) system, the method comprising: determining whether a torque sensor operates normally; Determining whether the angle sensor is operating normally if the torque sensor is malfunctioning; Switching to an MDPS temporary control mode using the angle sensor when the angle sensor operates normally; Rotating the steering wheel clockwise or counterclockwise by a predetermined reference angle; Measuring an operation angle of the driver in accordance with the steering wheel operation corresponding to the rotation of the steering wheel by the reference angle through the angle sensor; Comparing the steering wheel operating angle of the driver measured from the angle sensor with predetermined reference angle; And providing power to the motor for driving the steering wheel based on the comparison result, when the operating angle and the reference angle are different from each other, determining that there is steering intention of the driver.

According to another aspect of the present invention, there is provided an MDPS (Motor Driven Power Steering) system including: a torque sensor for measuring a torque of a steering wheel; An angle sensor for outputting an electric signal proportional to the rotation angle of the steering shaft; A motor for driving the steering wheel; A sensor check unit for checking whether the torque sensor and the angle sensor are in operation or not; And controlling the steering wheel to rotate by a reference angle set in a clockwise direction or a counterclockwise direction when the torque sensor is faulty and the angle sensor is judged normal by the sensor checking unit, The steering angle of the driver is measured by the angle sensor in accordance with the driver's manipulation of the steering wheel corresponding to the rotation, and the steering angle of the driver measured by the angle sensor is compared with the predetermined reference angle, And controlling the motor to provide power to the motor when the reference angle is different.

The present invention proposes a method of temporarily operating the steering wheel using the driver's will and the data received from the angle sensor when the driving of the MDPS system is interrupted due to the failure of the torque sensor as described above. By making the steering wheel temporarily operable by using the angle sensor as described above, the vehicle can be moved to a safe point in an emergency.

1 is a flow chart illustrating a method for controlling an MDPS system according to an embodiment of the present invention.
2 shows a configuration of an MDPS system according to an embodiment of the present invention.
3 is a diagram showing a general MDPS configuration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description.

Before describing the present invention in detail, the same components are denoted by the same reference symbols as possible even if they are displayed on different drawings. In the case where it is judged that the gist of the present invention may be blurred to a known configuration, do.

1 is a flow chart illustrating a method for controlling an MDPS system according to an embodiment of the present invention. Hereinafter, a method for controlling an MDPS system according to an embodiment of the present invention will be described in detail with reference to FIG.

The present invention proposes a method of controlling an MDPS system using a steering sensor when a torque sensor fails.

First, the MDPS system determines whether the torque sensor is malfunctioning (S101). The technique for determining whether or not the torque sensor is faulty is described in detail in the related art as described above, and thus the description will be omitted. If the torque sensor malfunctions, mark the MDPS warning light on the steering instrument panel to notify the driver of the fault and inspect it. Thereafter, in order to judge whether the MDPS temporary control is possible, the abnormality of the angle sensor is checked (S103).

On the other hand, when the torque sensor does not fail, the conventional MDPS control is performed using the torque measured by the torque sensor.

The MDPS system determines whether the angle sensor is abnormal. If the angle sensor fails, it is determined that the MDPS system can not be controlled finally, and the process is terminated. However, if the angle sensor does not fail, the mode is switched to the angle sensor control mode for temporary control of the MDPS system (S105). At this time, since the torque sensor is in a failure state, the MDPS warning lamp is continuously displayed on the instrument panel. In step S105, the MDPS system starts a control mode for controlling the MDPS using the angle sensor. Hereinafter, a process of controlling the MDPS using the angle sensor will be described.

The MDPS system moves the steering angle at a predetermined angle clockwise or counterclockwise to acquire data on the steering wheel operating angle (movement in the clockwise or counterclockwise direction) of the driver (S107). That is, since the torque sensor is broken, the steering wheel is arbitrarily moved clockwise or counterclockwise in order to collect data for judging the driver's intention to drive. According to one embodiment of the present invention, the MDPS system intentionally changes the steering angle in clockwise (CW) and / or counterclockwise (CCW) increments by one degree. Of course, depending on the setting, the MDPS system can move the steering wheel clockwise or counterclockwise to a value less than or greater than 1 degree, or set the angle of movement in the clockwise direction to be different from that in the counterclockwise direction.

When the MDPS system moves the steering wheel in the clockwise direction or the counterclockwise direction by one degree, the MDPS system determines the driving intention of the driver (S109). According to one embodiment of the present invention, the driving intention of the driver can be determined as shown in Table 1 below. Of course, in addition to the above-described method, the driver's will of driving can be determined in a different manner.

CW (deg) CCW (deg) No driving will One One Driving Will CW Weak Less than 1.1 to 1.0 or more 1 to less than 0.9 Driving Will CW Normal Less than 1.5 to 1.1 or more 0.9 or less to more than 0.5 Driving Will CW Strong 1.5 or more 0.5 or less Driving Will CCW Weak 1 to less than 0.9 Less than 1.1 to 1.0 or more Driving Will CCW Normal 0.9 or less to more than 0.5 Less than 1.5 to 1.1 or more Driving will CCW strong 0.5 or less 1.5 or more

According to the above-described Table 1, the driver's intention to drive is divided into seven stages, but the present invention is not limited thereto. The driver's willingness to drive may be less or more than seven, depending on the user's configuration.

Hereinafter, the meaning of Table 1 will be described in detail. If the MDPS system measures the rotation angle of the steering wheel operated by the driver after turning the steering wheel clockwise or counterclockwise by 1 degree and is 1 degree clockwise or 1 degree counterclockwise, If the angle of the steering wheel is equal to the angle of the steering wheel, it is determined that the driver has not operated the steering wheel separately.

Also, if the rotation angle of the steering wheel measured after the MDPS system rotates the steering wheel by 1 degree clockwise or counterclockwise is greater than 1.0 at less than 1.1 in the clockwise direction and greater than 0.9 degrees at less than 1 degree in the counterclockwise direction When the angle of the steering wheel rotated by the MDPS system is not equal to the angle of the steering wheel measured by the MDPS system and the rotational angle of the steering wheel is relatively increased in the clockwise direction while the rotational angle of the steering wheel is decreased in the counterclockwise direction, Since it is operated in the clockwise direction, the driver judges that the driver is willing to drive in the clockwise direction.

In addition, when the MDPS system rotates the steering wheel by 1 degree clockwise or counterclockwise, the rotation angle of the steering wheel is more than 1.1 degrees in less than 1.5 degrees in the clockwise direction and more than 0.5 degrees in less than 0.9 degrees in the counterclockwise direction The angle of the steering wheel rotated by the MDPS system is not the same as the angle of the steering wheel measured by the MDPS system and the rotational angle is increased in the clockwise direction relatively while the rotational angle is decreased in the counterclockwise direction, Since the steering wheel is operated in the clockwise direction, the driver judges that the driver is willing to drive in the clockwise direction. In addition, since the rotation angle of the clockwise rotation (1.1 or more at less than 1.5) is greater than the previous step (1.0 or more at less than 1.1), it is determined that the driver's will is relatively stronger in the clockwise direction than the previous step.

When the MDPS system has rotated the steering wheel by one degree in the clockwise or counterclockwise direction and the rotation angle of the steering wheel is 1.5 or more in the clockwise direction and 0.5 or less in the counterclockwise direction, When the angle of the wheel is not the same as the angle of the steering wheel measured later and the rotational angle is increased in a relatively clockwise direction while the rotational angle is decreasing in the counterclockwise direction, the driver operates the steering wheel clockwise, It is determined that there is an intention to drive in the direction of the driver. In addition, since the rotation angle (more than 1.5 degrees) rotated in the clockwise direction is larger than the previous step (more than 1.1 degrees in less than 1.5 degrees), it is determined that the driver's will is relatively stronger in the clockwise direction than the previous step.

Also, since the MDPS system has rotated the steering wheel by 1 degree clockwise or counterclockwise, the rotation angle of the steering wheel is greater than 0.9 degrees in the clockwise direction by less than 1 degree and less than 1.1 degrees in the counterclockwise direction In other words, when the angle of the steering wheel rotated by the MDPS system is not the same as the angle of the steering wheel measured later, and the rotational angle is decreased in the clockwise direction relatively while the rotational angle is increased in the counterclockwise direction, Since the steering wheel is operated counterclockwise, the driver judges that the driver is willing to operate in the counterclockwise direction.

Also, since the MDPS system has rotated the steering wheel by 1 degree clockwise or counterclockwise, the rotation angle of the steering wheel is more than 0.5 degrees in the clockwise direction at 0.9 degrees or less and 1.1 degrees or more at less than 1.5 degrees in the counterclockwise direction In other words, when the angle of the steering wheel rotated by the MDPS system is not the same as the angle of the steering wheel measured later, and the rotational angle is decreased in the clockwise direction relatively while the rotational angle is increased in the counterclockwise direction, Since the steering wheel is operated counterclockwise, the driver judges that the driver is willing to operate in the counterclockwise direction. In addition, the rotation angle (greater than or equal to 1.1 degrees at less than 1.5 degrees) rotated counterclockwise is greater than the previous step (greater than 1.0 degrees at less than 1.1 degrees), so that the driver's will is relatively stronger in the counterclockwise direction than the previous step .

Also, if the MDPS system has rotated the steering wheel by 1 degree in clockwise or counterclockwise direction and the rotation angle of the steering wheel is less than 0.5 degrees in the clockwise direction and 1.5 degrees in the counterclockwise direction, If the angle of the steering wheel is not the same as the angle of the steering wheel measured later and the rotation angle is decreased in the clockwise direction while the rotation angle is increased in the counterclockwise direction, the driver operates the steering wheel counterclockwise The driver judges that he is willing to drive in a counterclockwise direction. In addition, the rotation angle (greater than or equal to 1.1 degrees at less than 1.5 degrees) rotated counterclockwise is greater than the previous step (greater than 1.0 degrees at less than 1.1 degrees), so that the driver's will is relatively stronger in the counterclockwise direction than the previous step .

Of course, the numerical values set forth in Table 1 are illustrative of one embodiment of the present invention, and the present invention can also determine the driver's intention to drive using numerical values other than those shown in Table 1.

The MDPS system provides an assist force to the motor according to the driving intention of the driver measured in step S109 (S111). Table 2 below shows the assisting force provided to the motor according to the driving intention of the driver.

Motor control (Nm) No driving will 0 Driving Will CW Weak CW 0.5 Nm Driving Will CW Normal CW 1 Nm Driving Will CW Strong CW 2Nm Driving Will CCW Weak CCW 0.5 Nm Driving Will CCW Normal CCW 1Nm Driving will CCW strong CCW 2Nm

According to the above-mentioned Table 2, different assist forces of the motors are provided according to the determined driving intention of the driver. That is, a relatively high assist force is provided when the driver's will is stronger than when the driver's will is weak.

Figure 2 illustrates an MDPS system in accordance with an embodiment of the present invention. Hereinafter, an MDPS system according to an embodiment of the present invention will be described in detail with reference to FIG.

2, the MDPS system includes a steering wheel 10, a torque sensor 20, an angle sensor 30, a sensor checking unit 40, a control unit 50, a data collecting unit 60 and a storage unit 70, . Of course, other configurations than the above-described configuration may be included in the MDPS system proposed in the present invention.

The steering wheel 10 includes a steering wheel, a steering wheel, and a joystick as means for operating to change the traveling direction of the vehicle according to the driver's will. By operating the steering wheel 10, the vehicle can be rotated leftward or rightward.

The torque sensor 20 detects the torque T1 of the steering wheel 10. [ The angle sensor 30 outputs an electric signal proportional to the rotation angle of the steering shaft.

The sensor checking unit 40 checks whether the torque sensor 20 and the angle sensor 30 are abnormal.

The data collecting unit 60 collects electric signals output from the torque sensor 20 or the angle sensor 30 and provides the collected electric signals to the control unit 50.

The storage unit 70 stores the information described in Table 1 and Table 2 in the form of a table. That is, the storage unit 70 stores information as a reference for determining the driving intention of the driver as shown in Table 1, and stores information about the assist force provided to the motor according to the driver's intention determined as shown in Table 2 .

The controller 50 determines whether the torque sensor 20 is malfunctioning or receives an abnormality signal of the torque sensor 20 through the sensor checking unit 40. When the torque sensor 20 fails, the control unit 50 uses the electric signal of the angle sensor 30 provided from the data collecting unit 60 to determine the driver's intention to drive. That is, when the torque sensor 20 is malfunctioning, the control unit 50 controls the steering wheel to rotate by a set angle in a clockwise or counterclockwise direction. Thereafter, the control unit 50 calculates the rotation angle from the electric signal of the angle sensor 30 provided from the data collection unit 60, and determines the driver's will using the calculated rotation angle. The driver's willingness to drive can be composed of 7 steps such as no driving will, driving will CW weak, driving will CW normal, driving will CW strong, driving will CCW weak, driving will CCW normal, driving will CCW strong, May be less or more. The driver's intention to drive is determined to be driving if the calculated rotation angle is different from the set angle. The control unit 50 controls the motor to provide an assist force when there is an intention to drive the driver.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention.

Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

10: steering wheel 20: torque sensor
30: Angle sensor 60: Data collecting unit
50: control unit 70:

Claims

In an MDPS (Motor Driven Power Steering) system,
Determining whether the torque sensor is operating normally;
Determining whether the angle sensor is operating normally if the torque sensor is malfunctioning;
Switching to an MDPS temporary control mode using the angle sensor when the angle sensor operates normally;
Rotating the steering wheel clockwise or counterclockwise by a predetermined reference angle;
Measuring an operation angle of the driver in accordance with the steering wheel operation corresponding to the rotation of the steering wheel by the reference angle through the angle sensor;
Comparing the steering wheel operating angle of the driver measured from the angle sensor with predetermined reference angle;
And providing a power to the motor for driving the steering wheel when it is determined that there is steering intention of the driver when the operation angle is different from the reference angle.

The method according to claim 1,
The power supplied to the motor for driving the steering wheel differs depending on an operation angle at which the steering wheel is to be rotated,
Wherein the rotation angle of the steering wheel varies depending on a difference between the operation angle and the reference angle.

2. The method according to claim 1,
Controls the motor so as to drive the steering wheel in a clockwise direction if an angle in a clockwise direction of the operating angle is relatively larger than a clockwise angle in the reference angle,
Wherein the controller controls the motor to rotate the steering wheel in a counterclockwise direction when the counterclockwise angle of the operating angle is relatively larger than the counterclockwise angle of the reference angle.

The method of claim 3,
When the reference angle that rotates the steering wheel clockwise in the rotation step is a,
If the operation angle calculated in the determination step is 'a + alpha', the motor provides power having a magnitude of k,
If the operation angle calculated in the determining step is 'a + beta', the motor is provided with power having a magnitude of 'k + m'
Wherein the a is relatively larger than the beta, and k and m are positive real numbers.

2. The method according to claim 1,
Controls the motor to rotate the steering wheel counterclockwise when the angle of the operating angle in the clockwise direction is smaller than the clockwise angle of the reference angle,
Wherein the controller controls the motor to drive the steering wheel in a clockwise direction when the counterclockwise angle of the operating angle is relatively smaller than the counterclockwise angle of the reference angle.

In an MDPS (Motor Driven Power Steering) system,
A torque sensor for measuring a torque of the steering wheel;
An angle sensor for outputting an electric signal proportional to the rotation angle of the steering shaft;
A motor for driving the steering wheel;
A sensor check unit for checking whether the torque sensor and the angle sensor are in operation or not; And
Wherein the control unit controls the steering wheel to rotate by a reference angle set in a clockwise direction or a counterclockwise direction when the torque sensor is faulty and the angle sensor is determined to be normal at the sensor checking unit, The steering angle of the driver's steering wheel measured by the angle sensor is compared with the predetermined reference angle, and the comparison result is compared with the operating angle And to control power to the motor when the reference angle is different.

7. The apparatus of claim 6,
Controls the motor so as to drive the steering wheel in a clockwise direction when an angle in a clockwise direction of the operating angle is relatively larger than a clockwise angle in the reference angle,
And controls the motor to rotate the steering wheel counterclockwise if a counterclockwise angle of the operating angle is relatively larger than a counterclockwise angle of the reference angle.

The method according to claim 6,
The power supplied to the motor for driving the steering wheel differs depending on an operation angle at which the steering wheel is to be rotated,
Wherein the steering angle of the steering wheel varies depending on a difference between the operating angle and the reference angle.

The method according to claim 6,
Controls the motor so as to drive the steering wheel in a counterclockwise direction when an angle in a clockwise direction of the operating angle is smaller than a clockwise angle in the reference angle,
And controls the motor to drive the steering wheel in a clockwise direction when a counterclockwise angle of the operating angle is smaller than a counterclockwise angle of the reference angle.

8. The apparatus of claim 7,
When the reference angle that rotates the steering wheel clockwise is a,
Wherein the motor provides power having a magnitude of k if the operating angle measured through the angle sensor is 'a + a'
A motor having a magnitude of 'k + m' if the operating angle measured through the angle sensor is 'a + β'
Wherein the a is relatively larger than the beta and the k and m are positive real numbers.

The method according to claim 6,
And a data collecting unit for providing data collected by the torque sensor or the angle sensor to the control unit.

12. The method of claim 11,
Further comprising: a storage unit for storing a magnitude of power to be supplied to the motor according to a difference between the operation angle and the reference angle.