KR20120127947A - Control method of fail-safe for MDPS system - Google Patents

Control method of fail-safe for MDPS system Download PDF

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Publication number
KR20120127947A
KR20120127947A KR1020110045757A KR20110045757A KR20120127947A KR 20120127947 A KR20120127947 A KR 20120127947A KR 1020110045757 A KR1020110045757 A KR 1020110045757A KR 20110045757 A KR20110045757 A KR 20110045757A KR 20120127947 A KR20120127947 A KR 20120127947A
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KR
South Korea
Prior art keywords
motor
output shaft
torque sensor
input shaft
steering
Prior art date
Application number
KR1020110045757A
Other languages
Korean (ko)
Inventor
성우제
Original Assignee
현대자동차주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 현대자동차주식회사 filed Critical 현대자동차주식회사
Priority to KR1020110045757A priority Critical patent/KR20120127947A/en
Publication of KR20120127947A publication Critical patent/KR20120127947A/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D3/00—Steering gears
    • B62D3/02—Steering gears mechanical
    • B62D3/04—Steering gears mechanical of worm type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0409—Electric motor acting on the steering column
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0454—Worm gears
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B62D5/049—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures detecting sensor failures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/08—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque
    • B62D6/10—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque characterised by means for sensing or determining torque

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)

Abstract

In the present invention, the torsion bar is coupled to the input shaft and the output shaft, the input shaft is connected to the steering wheel and the output shaft is connected to the motor, the steering assistance force is provided to the output side according to the rotation angles of the input shaft and output shaft detected by the torque sensor A fail safe control method of a system, the method comprising: sensing a rotation angle of a steering wheel and a rotation angle of a motor to sense a rotation angle of an input shaft and an output shaft, respectively; And a failure determination step of determining a malfunction of the torque sensor by comparing the rotation angles of the input shaft and the output shaft received by the torque sensor with the values received in the sensing step.
The present invention having the configuration as described above can improve the reliability of the MPDS system, and in the past, the driver may feel a sudden heterogeneity due to the malfunction of the motor due to a malfunction, thereby improving the vehicle steering performance and stability. It works.

Description

Failsafe control method of MDPS system {Control method of fail-safe for MDPS system}

The present invention relates to a failsafe control method of a motor driving power steering (MDPS) system, and more particularly, to an MDPS system that can provide steering assistance power (assist force) of a motor even when an unexpected failure of a torque sensor occurs. The present invention relates to a failsafe control method.

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

Among them, the MDPS device is a device that uses the power of the motor instead of the hydraulic pressure, and has been widely used in passenger vehicles recently because it is light in weight, occupies little space, and does not require oil change, compared to the conventional hydraulic power steering device. .

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

Basically, MDPS system includes motor, steering gearbox, torque sensor and MDPS ECU. The MDPS ECU detects the amount of rotation 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, and the steering gear box receives the driving force through the steering shaft to change the rotation direction ( Rotate the front wheel through the arm (composed of relay rod, tie rod and knuckle arm).

The torque sensor typically uses an optical sensor. For example, the light receiving unit is installed on the torsion bar that rotates together with the steering wheel, and the light emitting unit is installed at a fixed point to measure the steering angle and the steering speed of the steering wheel.

Referring to the drawings in more detail, as shown in FIG. 1A, when the motor is attached to the steering column to provide the assist force (by the rotational force of the motor), a worm is coupled to the rotating shaft of the motor and the rotational force of the steering wheel is reduced. The torsion bar to be delivered is equipped with a worm gear meshing with the worm. The torsion bar is composed of an input shaft connected to the steering wheel and an output shaft connected to the gearbox through the steering shaft, the assist force of the motor is configured to be transmitted to the output shaft. An upper hall sensor and a lower hall sensor are attached to each of the input shaft and the output shaft, respectively, and as shown in FIG. 1B, the torque sensor may calculate a torsional torque (T sensor ) by detecting a difference in rotation angle between the input shaft and the output shaft. [T sensor = K torsion _ bar X (rotational displacement angle of input shaft-rotational displacement angle of output shaft), K torsion _ bar : stiffness coefficient of torsion bar (Nm / deg)]

Therefore, when the driver rotates the steering wheel, the MDPS ECU calculates a target current amount and applies a current to the motor according to the torsional torque measured by the torque sensor. The motor generates steering assistance by rotating the output shaft of the torsion bar with a worm and a worm wheel.

As described above, in the MDPS system, the torque sensor that measures the torsion bar's torsional torque and transmits the data to the MDPS ECU is a very important component. Therefore, a failure of the torque sensor may cause a malfunction in the vehicle operation and cause a fatal result. have.

Thus, conventionally, the upper hall sensor and the lower hall sensor operate in a manner of transmitting the main signal T1_main and the sub-signal T2_sub by crossing. The combination of the two signals can improve the reliability of the sensed data, but there is a problem in that the torque can not be detected when the power supply failure or the main signal and the sub signal occur at the same time. Therefore, in view of improving the reliability of the vehicle, it is required to develop a fail-safe control method that can determine the failure of the torque sensor and block it before the operation of the MDPS motor.

Meanwhile, in order to detect and predict the vehicle speed, the progress of the vehicle, and the driver's intention to drive according to the installation of the electronic control device of the vehicle, recently released vehicles detect a wheel speed sensor for detecting the speed of the wheel, and a lateral acceleration of the vehicle. It is common to include a lateral acceleration sensor, a yaw rate sensor for detecting a yaw moment and a steering angle sensor for detecting a rotation angle of a steering wheel.

Therefore, the present invention continuously monitors the presence of a malfunction of the torque sensor using a sensor provided in the vehicle without additional installation of an additional device, and if a malfunction of the torque sensor is detected, the driver is immediately notified and the minimum assist force required for driving is required. It is a main object to provide a fail-safe control method for providing a.

Accordingly, the present invention for achieving the above object, the torsion bar is coupled to the input shaft and the output shaft is connected to the input shaft is the steering wheel and the output shaft is connected to the motor, the rotation angle of the input shaft and output shaft detected by the torque sensor According to the fail-safe control method of the MDPS system provided with the steering assistance to the output side, the sensing step of sensing the rotation angle of the steering wheel and the rotation angle of the motor to sense the rotation angle of the input shaft and the output shaft, respectively; And a failure determination step of determining a malfunction of the torque sensor by comparing the rotation angles of the input shaft and the output shaft received by the torque sensor with the values received in the sensing step.

The motor is equipped with a worm, the output shaft of the torsion bar is equipped with a worm wheel (worm wheel) meshing with the worm, the motor is equipped with an encoder (encoder) for detecting the rotational speed of the motor.

In addition, the rotation angle of the steering wheel is sensed by a steering angle sensor.

In addition, the amount of current to be applied to the motor is determined according to the value received from the torque sensor, and if the malfunction of the torque sensor is determined in the fault determination step, the motor according to the rotation angle of the steering wheel sensed in the sensing step and the rotation angle of the motor. And a backup step of determining an amount of current to be applied.

The amount of current to be applied to the motor in the backup step is determined differentially according to the running speed of the vehicle and / or the lateral acceleration (lateral G) acting.

The present invention of the above configuration, it is possible to improve the reliability of the MPDS system by improving only the control logic without the installation of additional additional equipment.

In addition, in the related art, the driver may feel a sudden heterogeneity due to a malfunction of the motor due to a malfunction, thereby improving vehicle steering performance and stability by improving this.

In addition, it is possible to provide further improved stability by providing a differential assist force (according to a predetermined risk level) according to the driving state of the vehicle.

Figure 1a is a perspective view and an exploded perspective view showing the state of the steering column, motor, torsion bar of the steering device equipped with MDPS system,
1B is a schematic diagram of a conventional MDPS system,
1C is a graph of a main signal T1 and a sub signal T2 input and output to a torque sensor,
Figure 2 is a schematic diagram showing the appearance of additionally measuring the rotation angle of the input shaft and the output shaft according to the control method of the present invention,
3 and 4 is a flow chart illustrating a step of monitoring the presence of a failure of the torque sensor in accordance with the control method of the present invention,
5 is a flowchart of a control method of providing a differential assist force according to a driving state of a vehicle.

The vehicle according to the present invention is provided with a sensor that can measure the steering angle on the steering wheel. The sensor may be implemented by the steering angle sensor 10 as described above, the steering angle sensor 10 is implemented by a known technique including an optical sensor method using a light receiving unit and a light emitting unit.

In addition, the motor 20 used in the MDPS system of the present invention is engaged with the torsion bar by the worm 21 and the worm wheel (as shown in FIG. 1A), and includes an encoder. Using a known technique, the encoder is configured to measure the rotational speed and the rotational angle of the motor shaft using light receiving and light emitting elements (similar to the principle of measuring the rotational angle of the torque sensor as described above).

That is, the fail-safe control method according to the present invention is configured to separately sense the rotation angle of the steering wheel 11 and the rotation angle of the motor 20 separately from the torque sensor 50, and the sensed data is converted into a torque sensor ( The malfunction of the torque sensor is determined by comparing with the data received in step 50).

When the torque sensor 50 is detected as malfunctioning, the backup torque value is calculated according to the sensed rotation angle of the steering wheel 11 and the rotation angle of the motor 20, and the motor 20 is based on the backup torque value. Determine the amount of current to be applied. On the other hand, the amount of current to be applied to the motor 20 is preferably determined differentially based on the risk according to the running speed of the vehicle and / or the lateral acceleration acting.

Hereinafter, a failsafe control method of an MDPS system according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

For the torque value measurement of the torsion bar (generated in the steering wheel according to the intention of the driver), the angular change amount of the input shaft 30 and the angular change amount of the output shaft 40 are respectively measured. In the control method of the present invention, the data collected from the steering angle sensor 10 and the motor 20 are collected by a fail-safe controller (F / S: Fail-Safe controller).

That is, the data of the input shaft angular change amount θ upper is measured and collected from the steering angle sensor 10 separately from the upper hall sensor 51 of the torque sensor 50, and the output shaft angular change amount θ lower is recorded in the motor 20. It is measured and collected from the signal of the encoder. The angular change amount of the output shaft 40 may be calculated and measured from the rotational speed of the motor 20 and the gear ratio of the worm 21 and the worm wheel.

Then, in order to monitor the malfunction and failure of the torque sensor 50, the match between the torque sensor 50 output signal and the torsion bar torsion direction is checked. For example, as shown in the graph of FIG. 1C, when the CW (clockwise) torsion occurs, the main signal T1_main is 2.5 V or more and the sub signal T2_sub generates a value of 2.5 V or less, so that torque data of the torsion bar can be detected. have. Therefore, it is possible to monitor the presence or absence of the failure of the torque sensor 50 by comparing this signal with data measured by the encoder and / or steering angle sensor as described above.

For example, as shown in Figure 3, the torque data of the torsion bar is obtained from the main signal and the sub-signal of the torque sensor 50, the input shaft 30 and the output shaft in the pulse direction (motor rotation axis rotation direction) of the motor encoder By comparing the rotation angle of the 40 can monitor the presence or absence of the abnormality of the torque sensor (50). If the data of the torque sensor and the data of the encoder does not match, the fail-safe controller is configured to warn the driver by lighting a warning light on the instrument panel of the vehicle and is configured to control the power supply to the motor 20. The failsafe controller can be implemented in a known MDPS ECU through logic enhancement and communication extension.

In addition, the present invention together with the failure monitoring function of the torque sensor 50 may provide a backup function to replace the function of the torque sensor 50 based on the data received from the steering angle sensor 10 and the encoder.

That is, if the torque sensor is determined to be a failure, the driver provides a limp home mode (Limp Home Mode) so that the driver can temporarily drive to the repair shop without feeling heterogeneity. As shown in FIG. 4, the failsafe controller (or MDPS ECU) receives the displacement angle of the input shaft 30 from the steering angle sensor in place of the torque sensor and receives the rotation amount of the motor from the encoder. The failsafe controller may calculate the backup torque value T Back-up by calculating the rotation amount of the output shaft from the encoder data as described above. As described above, the driver may warn the driver of an abnormality of the MDPS system through a warning lamp, and may temporarily perform MDPS control by applying a current amount to the motor based on the backup torque value.

In addition, as an optional embodiment, when the fault monitoring function and the backup function of the present invention are implemented, the heterogeneity of the driver may be minimized by differentially applying the MDPS assist force step by step according to the driving situation of the vehicle.

That is, the lateral acceleration acting upon the turning of the vehicle varies according to the traveling speed of the vehicle, and thus the operability and risk of the driver are changed. For example, in high-speed turning with more than 0.5g of lateral acceleration, the driving frequency is small, but there is a high degree of risk in case of accident and the driver's manipulation is not good. This is relatively straightforward and low risk.

Therefore, by setting the risk level and the reference value in advance according to the vehicle speed, steering angle, and the acting lateral acceleration, and controlling the amount of current applied to the motor based on the reference value (as shown in FIG. 5), the assist force is differentially provided step by step. can do.

As described above, the embodiments disclosed in the present specification and drawings are only illustrative of specific examples in order to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: steering angle sensor
11: steering wheel
20: motor
30: input shaft
40: output shaft
50: torque sensor

Claims (5)

Torsion bar combined with input shaft and output shaft has the input shaft connected to the steering wheel, the output shaft connected to the motor, and the fail-safe of the MDPS system, which provides steering assistance on the output side according to the rotation angles of the input shaft and output shaft detected by the torque sensor. In the control method,
Sensing a rotation angle of the steering wheel and a rotation angle of the motor to sense rotation angles of the input shaft and the output shaft, respectively; And
And a failure determination step of determining a malfunction of the torque sensor by comparing the rotation angles of the input shaft and the output shaft received by the torque sensor with the values received in the sensing step.
According to claim 1, wherein the motor is equipped with a worm (worm) and the output shaft of the torsion bar is equipped with a worm wheel (worm wheel) to be engaged with the worm, the motor is an encoder (encoder) for detecting the rotational speed of the motor Fail-safe control method of the MDPS system, characterized in that mounted.
The method of claim 2, wherein the rotation angle of the steering wheel is sensed by a steering angle sensor.
According to any one of claims 1 to 3, wherein the motor is the amount of current to be applied according to the value received from the torque sensor,
And a backup step in which a current amount to be applied to the motor is determined according to the rotation angle of the steering wheel sensed in the sensing step and the rotation angle of the motor when the malfunction of the torque sensor is determined in the fault determination step. How to control failsafe.
5. The method of claim 4, wherein the amount of current to be applied to the motor in the backup step is determined according to the lateral acceleration of the vehicle.
KR1020110045757A 2011-05-16 2011-05-16 Control method of fail-safe for MDPS system KR20120127947A (en)

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KR1020110045757A KR20120127947A (en) 2011-05-16 2011-05-16 Control method of fail-safe for MDPS system

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150027911A (en) * 2013-09-04 2015-03-13 현대모비스 주식회사 Sensor power interface for Motor Driven Power Steering for vehicle, and control method thereof
KR20200116183A (en) * 2019-03-12 2020-10-12 주식회사 만도 Apparatus and method for security verification of autonomous vehicle
CN113840770A (en) * 2019-05-16 2021-12-24 株式会社万都 Steering control device, steering control method, and steering control system
KR20230087994A (en) 2021-12-10 2023-06-19 빛그린전기차협동조합 Hybrid steering system for automobiles

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150027911A (en) * 2013-09-04 2015-03-13 현대모비스 주식회사 Sensor power interface for Motor Driven Power Steering for vehicle, and control method thereof
KR20200116183A (en) * 2019-03-12 2020-10-12 주식회사 만도 Apparatus and method for security verification of autonomous vehicle
CN113840770A (en) * 2019-05-16 2021-12-24 株式会社万都 Steering control device, steering control method, and steering control system
CN113840770B (en) * 2019-05-16 2024-06-11 汉拿万都株式会社 Steering control device, control method, and steering control system
KR20230087994A (en) 2021-12-10 2023-06-19 빛그린전기차협동조합 Hybrid steering system for automobiles

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