Apparatus and method for detecting a failure of a torque sensor for a motor-driven power steering system

Abstract

Apparatus for detecting a failure of a torque sensor for a motor-driven power steering system, the apparatus comprising: a memory (110); Torque sensors comprising a first torque sensor (122) and a second torque sensor (124); and a processor (140) connected to the memory (110) and the torque sensor, wherein the processor (140) detects whether the first torque sensor (122) and the second torque sensor (124) fail based on main torque signals and sub-torque signals from the first torque sensor (122) and the second torque sensor, wherein the processor (140) compares a first torque value of the first torque sensor (122) and a second torque value of the second torque sensor (124) in the event that the detection result indicates that the first torque sensor (122) and the second torque sensor (124) are normal, wherein the processor (140) measures the amount of change in the first torque of the first torque sensor (122) and the amount of change in the second torque of the second torque sensor (124) by applying electric current to a motor if the comparison result is abnormal, and wherein the processor (140) finally detects whether the first torque sensor and the second torque sensor (124) are failing based on the amount of change in the first torque and the amount of change in the second torque, wherein the processor (140) calculates a first difference between a column torque value of the first main torque signal of the first torque sensor (122) and a column torque value of the first sub-torque signal of the first torque sensor (122), wherein the processor (140) diagnoses the first torque sensor (122) with a fault if a condition in which the first difference is greater than a preset first reference torque value and equal to or less than a preset second reference torque value is maintained for a first reference time or longer, or if a condition in which the first difference is greater than the second reference torque value is maintained for a second reference time or longer.

Description

BACKGROUND AREA

[0001] Exemplary embodiments of the present disclosure relate to a torque sensor failure detection apparatus and method for a motor-driven power steering system, and more particularly, to a torque sensor failure detection apparatus and method for a motor-driven power steering system capable of normally detecting a torque sensor failure when a torque signal is transmitted within a normal range set for failure detection even though the torque sensor is damaged by external environmental factors. DISCUSSION OF THE BACKGROUND

[0002] Generally, a motor-driven power steering (MDPS) system uses an electric motor and supplies assist torque in a direction in which a driver steers a vehicle, allowing the driver to smoothly operate a steering wheel. Unlike a prior art hydraulic power steering (HPS) system, the motor-driven power steering system can automatically control operation of the electric motor based on a driving condition of the vehicle, thereby improving steering performance and steerability. In this case, the motor-driven power steering system includes a torque sensor configured to measure the steering torque input by the driver to the steering wheel, a steering angle sensor configured to measure a steering angle of the steering wheel, a vehicle speed sensor configured to measure a vehicle speed, and the like, and determines the driving condition of the vehicle.

[0003] Meanwhile, two torque sensors were used for the motor-driven power steering system to improve redundant operation. In the event that one torque sensor fails, the motor-driven power steering system normally operates using the other normal torque sensor. In the event that both torque sensors fail, the motor-driven power steering system is switched to a manual mode. In this case, the failure of each torque sensor is detected by checking a normal range of a voltage value of a torque signal and comparing two torque voltage values ​​in the torque sensors. That is, the detection of torque sensor failure is performed by checking whether the torque voltage values ​​of the two torque sensors are within the normal range and whether a torque voltage difference is within a normal range.If the voltage value deviates from the normal range, a failure of the torque sensor is diagnosed.

[0004] Torque sensor failure detection can be performed when a voltage outside the normal range is transmitted due to the torque signal being shorted / opened with a nearby reference voltage, GND, or the like. However, if a voltage within the normal range is transmitted even though the torque sensor is damaged by external environmental influences such as water (salt or corrosion), the torque sensor failure cannot usually be detected. Therefore, a problem exists in that an abnormal torque value is consistently used, leading to dangerous movements such as self-rotation.

[0005] The background technology of the present disclosure is disclosed in Korean Patent Application Publication No. KR 10 2008 0 078 428 A (published on August 27, 2008 and titled "TORQUE SENSOR CENTER POINT COMPENSATION METHOD FOR USE IN ELECTRIC POWER STEERING APPARATUS").

[0006] DE 10 2009 005 836 A1 discloses a steering device. The steering device has two redundant torque sensors, whereby if one of the torque sensors fails, the data from the other torque sensor is checked for plausibility.

[0007] An electric steering system is known from DE 10 2018 218 103 A1. The electric steering system uses three- or four-channel torque sensors, with each torque signal value being used for control. This torque signal value is used concurrently by two or more of the torque channels.

[0008] DE 11 2014 004 320 B4 discloses an electric steering system with a torque sensor. The torque sensor includes a main and sub-torque sensor. Abnormalities in the main and sub-torque sensors are detected by comparing the plurality of sensor output signals. Identification of the abnormality at a later time is enabled by storing the detected abnormality information in a non-volatile memory.

[0009] Various embodiments relate to a torque sensor failure detection apparatus and method for a motor-driven power steering system, which are capable of normally detecting a torque sensor failure when a torque signal is transmitted within a normal range set for failure detection even though the torque sensor is damaged by external environmental factors.

[0010] The above object is achieved by a device having the features of claim 1 and a method having the features of claim 10. Advantageous further developments emerge from the subclaims.

[0011] In one embodiment, an apparatus for detecting a failure of a torque sensor for a motor-driven power steering system comprises: a memory; torque sensors including a first torque sensor and a second torque sensor; and a processor connected to the memory and the torque sensor, wherein the processor detects whether the first torque sensor and the second torque sensor are failing based on main torque signals and sub-torque signals of the first torque sensor and the second torque sensor, wherein the processor compares a first torque value of the first torque sensor and a second torque value of the second torque sensor if the detection result indicates that the first torque sensor and the second torque sensor are normal,wherein the processor measures the amount of change in the first torque of the first torque sensor and the amount of change in the second torque of the second torque sensor by applying an electric current to a motor if the comparison result is abnormal, and wherein the processor finally detects whether the first torque sensor and the second torque sensor are failing based on the amount of change in the first torque and the amount of change in the second torque.

[0012] In the present disclosure, the processor calculates a first difference between a column torque value of a first main torque signal of the first torque sensor and a column torque value of a first sub-torque signal of the first torque sensor. The processor diagnoses a failure of the first torque sensor when a condition in which the first difference is greater than a preset first reference torque value and equal to or less than a preset second reference torque value is maintained for a first reference time or longer, or when a condition in which the first difference is greater than the second reference torque value is maintained for a second reference time or longer.the processor calculates a second difference between a column torque value of a second main torque signal of the second torque sensor and a column torque value of a second sub-torque signal of the second torque sensor. The processor diagnoses a fault of the second torque sensor if a condition in which the second difference is greater than the first reference torque value and equal to or less than the second reference torque value is maintained for the first reference time or longer, or if a condition in which the second difference is greater than the second reference torque value is maintained for the second reference time or longer, wherein the first reference torque value is less than the second reference torque value and the first reference time is longer than the second reference time.

[0013] In the present disclosure, the processor may calculate the first torque value based on a column torque value of a first main torque signal of the first torque sensor and a column torque value of a first sub-torque signal of the first torque sensor, the processor may calculate the second torque value based on a column torque value of a second main torque signal of the second torque sensor and a column torque value of a second sub-torque signal of the second torque sensor, the processor may calculate a third difference that is a difference between the first torque value and the second torque value, the processor may determine that the first torque sensor or the second torque sensor is abnormal if a condition,in which the third difference is greater than a preset third reference torque value and equal to or less than a preset fourth reference torque value, is maintained for a third reference time or longer, or if a state in which the third difference is greater than the fourth reference torque value is maintained for a fourth reference time or longer, wherein the third reference torque value may be less than the fourth reference torque value, and the third reference time may be longer than the fourth reference time.

[0014] In the present disclosure, the processor may determine that the first torque sensor is normal if the amount of change in the first torque varies, the processor may determine that the first torque sensor is failing if the amount of change in the first torque does not vary, the processor may determine that the second torque sensor is normal if the amount of change in the second torque varies, and the processor may determine that the second torque sensor is failing if the amount of change in the second torque does not vary.

[0015] In the present disclosure, when a vehicle is turned on, the processor may select a normal torque sensor between the first torque sensor and the second torque sensor based on torque sensor failure information stored in the memory, and detect failures of the normal torque sensor and the other torque sensor while controlling the engine using the torque signal from the selected normal torque sensor, and when the vehicle is turned off, the processor may update the torque sensor failure information stored in the memory based on the failure detection result.

[0016] In the present disclosure, the processor may determine whether the other torque sensor is normal based on the torque sensor failure information if a failure of the normal torque sensor is diagnosed, the processor may use the other torque sensor for a control process if the other torque sensor is normal, and the processor may change a mode to a limp home mode or a manual mode if the other torque sensor fails.

[0017] In one embodiment, a method for detecting a failure of a torque sensor for a motor-driven power steering system comprises: selecting, by a processor, a normal torque sensor between a first torque sensor and a second torque sensor based on torque sensor failure information stored in a memory when a vehicle is turned on; detecting, by the processor, failures of the normal torque sensor and the other torque sensor while controlling a motor using a torque signal from the selected normal torque sensor; and updating, by the processor, the torque sensor failure information stored in the memory based on the failure detection result when the vehicle is turned off.

[0018] In the present disclosure, in the fault detection, the processor detects whether the first torque sensor and the second torque sensor are failing based on main torque signals and sub-torque signals of the first torque sensor and the second torque sensor. The processor compares a first torque value of the first torque sensor and a second torque value of the second torque sensor if the detection result indicates that the first torque sensor and the second torque sensor are normal. The processor measures the amount of change in the first torque of the first torque sensor and the amount of change in the second torque of the second torque sensor by applying electric current to a motor if the comparison result is abnormal. Finally, the processor determines based on the amount of change in the first torque and the amount of change in the second torque,whether the first torque sensor and the second torque sensor fail.

[0019] In the present disclosure, in the fault detection, the processor may determine that the first torque sensor is normal if the amount of change in the first torque varies, the processor may determine that the first torque sensor is failing if the amount of change in the first torque does not vary, the processor may determine that the second torque sensor is normal if the amount of change in the second torque varies, and the processor may determine that the second torque sensor is failing if the amount of change in the second torque does not vary.

[0020] In the present disclosure, in the fault detection, the processor may determine whether the other torque sensor is normal based on the information about the failure of the torque sensor if the normal torque sensor is diagnosed with a fault, the processor may use the other torque sensor for a control process if the other torque sensor is normal, and the processor may change a mode to a limp home mode or a manual mode if the other torque sensor fails.

[0021] The torque sensor failure detection apparatus and method for a motor-driven power steering system according to one aspect of the present disclosure can detect whether the first torque sensor and the second torque sensor are failing based on the main torque signals and the sub-torque signals of the first torque sensor and the second torque sensor. If the detection result indicates that the first torque sensor and the second torque sensor are normal, the apparatus and method can compare the first torque value of the first torque sensor and the second torque value of the second torque sensor and again detect whether the first torque sensor and the second torque sensor are failing.Therefore, the device and method can normally detect the failure of the torque sensor when the torque signal is transmitted within the normal range set for failure detection, even if the torque sensor is damaged by external environmental factors. Therefore, the present disclosure can solve the self-rotation problem that occurs when a fixed torque value is output within a normal range. Furthermore, the present disclosure can improve the stability of the vehicle and the driver.

[0022] The torque sensor failure detection apparatus and method for a motor-driven power steering system according to one aspect of the present disclosure can store the information on the failure of the failed torque sensor during the ongoing operation of the vehicle and then operate the torque sensor used as a backup based on the torque sensor failure information stored in the previous cycle when the vehicle is turned on again, thereby making it possible to effectively cope with the occurrence of the torque sensor failure.

[0023] However, the effects of the present disclosure are not limited to the above-mentioned effects, and various effects can be included within a range apparent to those skilled in the art from the following description. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a view for explaining a torque sensor failure detection apparatus for a motor-driven power steering system according to an embodiment of the present disclosure. Fig. 2 is an exemplary view for explaining a method for detecting failures of a first torque sensor and a second torque sensor according to the embodiment of the present disclosure. Fig. 3 is a flowchart for explaining a method for detecting a failure of a torque sensor for a motor-driven power steering system according to the embodiment of the present disclosure. Fig. 4 is a flowchart for explaining a method for detecting a failure of a torque sensor according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0024] The components described in the embodiments may be implemented by hardware components, e.g., by at least one digital signal processor (DSP), a processor, a controller, an application-specific integrated circuit (ASIC), a programmable logic element such as an FPGA, other electronic devices, or combinations thereof. At least some of the functions or processes described in the embodiments may be implemented by software, and the software may be recorded on a recording medium. The components, functions, and processes described in the embodiments may be implemented by a combination of hardware and software.

[0025] The method according to embodiments may be embodied as a computer-executable program and may be implemented on various recording media such as a magnetic storage medium, an optical reading medium, and a digital storage medium.

[0026] Various techniques described herein may be implemented as digital electronic circuits or as computer hardware, firmware, software, or combinations thereof. The techniques may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., a machine-readable storage medium (e.g., a computer-readable medium), or in a transmitted signal for processing by a data processing device or for controlling the operation of a data processing device, e.g., a programmable processor, a computer, or multiple computers.A computer program may be written in any form of programming language, including compiled or interpreted languages, and may be implemented in any form, including a stand-alone program or a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may be designed to run on one computer or on multiple computers at one or more locations, distributed across multiple locations, and interconnected by a communications network.

[0027] Processors suitable for executing a computer program include, for example, both general-purpose and special-purpose microprocessors, as well as one or more processors of all types of digital computers. Generally, a processor receives instructions and data from read-only memory or random access memory, or both. Elements of a computer may include at least one processor for executing instructions and one or more memories for storing instructions and data. Generally, a computer also includes, or is coupled to, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks, for receiving data from, transferring data to, or both. Examples of information carriers suitable for embodying computer program instructions and data include semiconductor storage devices, such asMagnetic media such as a hard disk, a floppy disk, and magnetic tape; optical media such as a compact disk read-only memory (CD-ROM), a digital video disk (DVD), etc.; and magneto-optical media such as a floppy disk, read-only memory (ROM), random-access memory (RAM), flash memory, erasable programmable ROM (EPROM), and electrically erasable programmable ROM (EEPROM), as well as any other known computer-readable medium. A processor and memory may be supplemented by or integrated with dedicated logic circuitry.

[0028] The processor may execute an operating system (OS) and one or more software applications running on the OS. The processor device may also access, store, manipulate, process, and create data in response to the execution of the software. For simplicity, the description of a processor unit is used in the singular; however, one of ordinary skill in the art will appreciate that a processor unit may include multiple processing elements and / or multiple types of processing elements. For example, a processor unit may include multiple processors or a processor and a controller. Furthermore, various processing configurations are possible, such as parallel processors.

[0029] Non-transitory computer-readable media can be any available media that can be accessed by a computer and can include both computer storage media and transmission media.

[0030] This specification contains details of a number of specific embodiments, but it should be understood that the details do not limit any invention or what may be claimed in the specification, but rather describe features of the specific example embodiment. Features described in the specification in connection with individual embodiments may be implemented in combination in a single embodiment. In contrast, various features described in the specification in connection with a single embodiment may be implemented in multiple embodiments individually or in any suitable subcombination.Furthermore, the features may operate in a particular combination and be initially described as a claimed combination, but one or more features may in some cases be excluded from the claimed combination, and the claimed combination may be changed to a sub-combination or a variation of a sub-combination.

[0031] Although the operations in the drawings are described in a particular order, this should not be understood to mean that the operations must be performed in that order or in the correct order to achieve the desired results, or that all operations must be performed. In a particular case, multitasking and parallel processing may be advantageous. Furthermore, it should not be understood that separation of various device components in the embodiments described above is required in all embodiments, and it should be understood that the program components and devices described above may be integrated into a single software product or packaged into multiple software products.

[0032] It is to be understood that the embodiments disclosed herein are for illustrative purposes only and are not intended to limit the scope of the invention. It will be apparent to one skilled in the art that various modifications to the embodiments may be made without departing from the spirit and scope of the claims and their equivalents.

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that a person skilled in the art can readily practice the present disclosure. However, the present disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0034] In the following description of the embodiments of the present disclosure, a detailed description of well-known functions and configurations will be omitted if doing so might obscure the subject matter of the present disclosure. Parts not related to the description of the present disclosure in the drawings are omitted, and like parts are denoted by like reference numerals.

[0035] In this disclosure, individual components are distinguished from one another to clarify individual features. However, this does not necessarily mean that the components are separate. That is, a plurality of components may be integrated into a single hardware or software unit, or a single component may be distributed across multiple hardware or software units. Unless otherwise stated, such integrated or distributed embodiments are also within the scope of this disclosure.

[0036] In the present disclosure, the components described in the various embodiments are not necessarily essential components, and some may be optional components. Accordingly, embodiments consisting of a subset of the components described in an embodiment are also within the scope of the present disclosure. Furthermore, embodiments that include further components in addition to the components described in the various embodiments are also included within the scope of the present disclosure.

[0037] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that a person skilled in the art can readily practice the present disclosure. However, the present disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0038] In the following description of the embodiments of the present disclosure, detailed descriptions of well-known functions and configurations will be omitted when doing so might obscure the subject matter of the present disclosure. Parts not related to the description of the present disclosure in the drawings are omitted, and like parts are denoted by like reference numerals.

[0039] Whenever this disclosure refers to a component being "linked," "coupled," or "connected" to another component, this may refer not only to a direct connection, but also to an indirect connection via an intervening component. When a component is referred to as "comprising" or "having" another component, this may refer to the inclusion of another component, not its exclusion, unless expressly described to the contrary.

[0040] In this disclosure, the terms "first," "second," etc., are used only to distinguish between individual components and do not limit the order or importance of components, etc., unless expressly stated otherwise. Thus, throughout this disclosure, a first component in one exemplary embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one exemplary embodiment may be referred to as a first component.

[0041] In this disclosure, individual components are distinguished from one another to clarify individual features. However, this does not necessarily mean that the components are separate. That is, a plurality of components may be integrated into a single hardware or software unit, or a single component may be distributed across multiple hardware or software units. Unless otherwise stated, such integrated or distributed embodiments are also within the scope of this disclosure.

[0042] In the present disclosure, the components described in the various embodiments are not necessarily essential components, and some may be optional components. Accordingly, embodiments consisting of a subset of the components described in an embodiment are also within the scope of the present disclosure. Furthermore, example embodiments that include additional components in addition to the components described in the various embodiments are also included within the scope of the present disclosure.

[0043] An apparatus and method for detecting a failure of a torque sensor for a motor-driven power steering system will be described below with reference to the accompanying drawings using various exemplary embodiments.

[0044] Fig.1 is a view for explaining a torque sensor failure detection apparatus for a motor-driven power steering system according to an embodiment of the present disclosure, and Fig. 2 is an explanatory view for explaining a method for detecting errors of a first torque sensor and a second torque sensor according to the embodiment of the present disclosure.

[0045] Referring to Fig. 1, an apparatus 100 for detecting a torque sensor failure for a motor-driven power steering system according to an embodiment of the present disclosure includes a memory 110, torque sensors 120, a processor 140, and a motor 130.

[0046] The memory 110 is configured to store data related to operations of the torque sensor failure detection device 100. In particular, the memory 110 may store information about the torque sensor failure. Furthermore, the memory 110 may store applications (programs or applets) and the like that can be used to detect a failure of the torque sensor 120. The stored information can be selected by the processor 140 as needed. That is, the memory 110 stores various types of data generated during a process of executing an operating system or an application (a program or an applet) for operating the torque sensor failure detection device 100.In this case, the memory 110 is collectively referred to as a non-volatile storage device configured to continuously maintain the stored information even when no electrical power is supplied, and a volatile storage device configured to require electrical power to maintain the stored information. Furthermore, the memory 110 may be used to temporarily or permanently store data to be processed by the processor 140. In this case, the memory 110 may include magnetic storage media or flash storage media in addition to the volatile storage device configured to require electrical power to maintain the stored information. However, the scope of the present disclosure is not limited thereto.

[0047] The torque sensor 120 may generate an electrical signal by detecting a relative rotational displacement between an input shaft and an output shaft in accordance with rotation of a steering wheel (not shown) and transmitting the generated electrical signal to the processor 140. That is, the torque sensor 120 may detect a column torque generated by a steering operation of the steering wheel and transmit the column torque to the processor 140.

[0048] The torque sensor 120 has a dual structure and includes a first torque sensor 122 and a second torque sensor 124. To detect failures of the torque sensors, the first torque sensor 122 is provided as a pair of first torque sensors, and the second torque sensor 124 is provided as a pair of second torque sensors. That is, the first torque sensors 122 may include a first main torque sensor (Torque Sensor Master (TSM)) and a first sub-torque sensor (Torque Sensor Slave (TSS)), and the second torque sensors 124 may include a second main torque sensor and a second sub-torque sensor.

[0049] The motor 130 can generate assist power to make the steering smooth. The motor 130 can generate a preset drive power in a preset direction based on a control signal or electric current supplied by the processor 140. That is, the motor 130 can generate steering assist power from the drive power by operating with electric current supplied in response to the assist torque.

[0050] The processor 140 may receive a vehicle speed, column torque, steering angle, and motor angle from a vehicle speed sensor (not shown), the torque sensor 120, a steering angle sensor (not shown), and a motor angle sensor (not shown), calculate the assist torque, and operate the motor 130. The processor 140 may receive various types of signals from the sensors, detect a driving state of the vehicle based on the received signals, and then adjust the amount of electric current flowing through the motor 130, thereby controlling the operation of the motor 130.

[0051] Furthermore, the processor 140 may select the normal torque sensor between the first torque sensor 122 and the second torque sensor 124 based on the torque sensor failure information stored in the memory 110 when the vehicle is turned on, and the processor 140 may detect whether the normal torque sensor and the other torque sensor are failing while controlling the engine 130 using a torque signal from the selected normal torque sensor. In this case, if the normal torque sensor is diagnosed with a failure, the processor 140 determines whether the other torque sensor is normal based on the torque sensor failure information. If the other torque sensor is normal, the processor 140 may use the other torque sensor for a control process.If the other torque sensor fails, the processor 140 may change a mode to an emergency mode or a manual mode.

[0052] As in Fig. 2, the processor 140 may detect whether the first torque sensor 122 and the second torque sensor 124 are failing based on the main torque signals and the sub-torque signals of the first torque sensor 122 and the second torque sensor 124. If the detection result indicates that both the first torque sensor 122 and the second torque sensor 124 are normal, the processor 140 may finally detect whether the first torque sensor 122 and the second torque sensor 124 are failing based on a first torque value of the first torque sensor 122 and a second torque value of the second torque sensor 124.

[0053] First, based on the main torque signals and the sub-torque signals of the first torque sensor 122 and the second torque sensor 124, the processor 140 may determine whether the first torque sensor 122 and the second torque sensor 124 are failing.

[0054] Specifically, the processor 140 may calculate a first difference indicating a difference between a column torque value of the first main torque signal of the first torque sensor 122 and a column torque value of the first sub-torque signal of the first torque sensor 122. Thereafter, if a condition in which the first difference is greater than a preset first reference torque value and equal to or less than a preset second reference torque value is maintained for a first reference time or longer, or if a condition in which the first difference is greater than the second reference torque value is maintained for a second reference time or longer, the processor 140 may diagnose the first torque sensor 122 with a fault. In this case, the column torque value may be a value obtained by converting the torque voltage value into the column torque value.The first reference torque value may be smaller than the second reference torque value, and the first reference time may be longer than the second reference time.

[0055] Additionally, the processor 140 may calculate a second difference indicating a difference between a column torque value of the second main torque signal of the second torque sensor 124 and a column torque value of the second sub-torque signal of the second torque sensor 124. Thereafter, if a state where the second difference is greater than the first reference torque value and equal to or less than the second reference torque value is maintained for the first reference time or longer, or if a state where the second difference is greater than the second reference torque value is maintained for the second reference time or longer, the processor 140 may diagnose the second torque sensor 124 with a fault.

[0056] If a first fault detection result based on the main torque signals and the sub-torque signals of the first torque sensor 122 and the second torque sensor 124 indicates that both the first torque sensor 122 and the second torque sensor 124 are normal, the processor 140 may again detect whether the first torque sensor 122 and the second torque sensor 124 are failing based on the first torque value of the first torque sensor 122 and the second torque value of the second torque sensor 124.

[0057] Specifically, the processor 140 may calculate the first torque value based on the column torque value of the first main torque signal of the first torque sensor 122 and the column torque value of the first sub-torque signal of the first torque sensor 122, and calculate the second torque value based on the column torque value of the second main torque signal of the second torque sensor 124 and the column torque value of the second sub-torque signal of the second torque sensor 124. In this case, the processor 140 may calculate, as the first torque value, an average of the column torque value of the first main torque signal and the column torque value of the first sub-torque signal, and calculate, as the second torque value, an average of the column torque value of the second main torque signal and the column torque value of the second sub-torque signal.

[0058] Next, the processor 140 calculates a third difference indicating a difference between the first torque value and the second torque value. If a state in which the third difference is greater than a preset third reference torque value and equal to or less than a preset fourth reference torque value is maintained for a third reference time or longer, or if a state in which the third difference is greater than the fourth reference torque value is maintained for a fourth reference time or longer, the processor 140 may determine that the first torque sensor 122 or the second torque sensor 124 is abnormal. In this case, the third reference torque value may be less than the fourth reference torque value, and the third reference time may be longer than the fourth reference time.

[0059] If the state in which the third difference is greater than the preset third reference torque value and equal to or less than the preset fourth reference torque value is maintained for the third reference time or longer, or if the state in which the third difference is greater than the fourth reference torque value is maintained for the fourth reference time or longer (that is, if a result of a comparison of the first torque value and the second torque value is abnormal), the processor 140 may measure the amount of change in the first torque of the first torque sensor 122 and the amount of change in the second torque of the second torque sensor 124 by applying electric current to the motor 130.In this case, the processor 140 may apply the electric current to the motor 130 based on a preset electric current magnitude and electric current application time to give a driver a small amount of vibration without affecting the driving of the vehicle.

[0060] Finally, the processor 140 may determine whether the first torque sensor 122 and the second torque sensor 124 are failing based on the amount of change in the first torque and the amount of change in the second torque. That is, if the amount of change in the first torque varies, the processor 140 may determine that the first torque sensor 122 is normal. If the amount of change in the first torque does not vary, the processor 140 may diagnose a failure of the first torque sensor 122. If the amount of change in the second torque varies, the processor 140 may also determine that the second torque sensor 124 is normal. If the amount of change in the second torque does not vary, the processor 140 may diagnose a failure of the second torque sensor 124.

[0061] Additionally, when the vehicle is parked, the processor 140 may update the torque sensor failure information stored in the memory 110 based on the result of the fault detection. In this case, the processor 140 may update the torque sensor failure information as shown in Table 1 below. [Table 1] classification First torque sensor Second torque sensor Control torque Notes First torque sensor Normal -> Failure Normal Second torque value 1. Use of second torque value as control signal immediately if first torque sensor fails 2. Save information about failure of first torque sensor in ROM Second torque sensor Continuous failure Normal Second torque value 1. Reading NVM information and using second torque sensor as basic control signal 2. Prohibit first torque sensor for control operation and continue only first detection of failure of first torque sensor -> continue detection of failure of first torque sensor Third torque sensor Recovery to normal Normal Second torque value 1. Reading NVM information and using second torque sensor as basic control signal 2. Checking removal of failure of first torque sensor 1 -> Deleting information about occurrence of failure of first torque sensor from NVM *Recovery condition: Non-detection of failure related to torque sensor for 1 key cycle Fourth torque sensor Normal Normal First torque value or second torque value Reading NVM information and using first torque sensor or second torque sensor as base control signal

[0062] Referring to Table 1, when the first torque sensor 122 fails during a first operation (drive) (1st key cycle) of the vehicle, the processor 140 may immediately use the second torque value of the second torque sensor 124 in the normal state as a control signal when the first torque sensor 122 fails. When the vehicle is parked, the processor 140 may store the information about the occurrence of the failure of the first torque sensor 122 in the memory 110.

[0063] Thereafter, when the vehicle is turned on (second key cycle), the processor 140 can read the torque sensor failure information from the memory 110 and use the second torque value of the second torque sensor 124 as the control signal. Since the first torque sensor 122 is in the failed state in this case, the processor 140 does not use the first torque sensor 122 and can continuously detect the failure of the first torque sensor 122. When the vehicle is turned off, the processor 140 can retain the torque sensor failure information stored in the memory 110.

[0064] Thereafter, when the vehicle is turned on (3rd key cycle), the processor 140 may read the information about the torque sensor failure from the memory 110 and use the second torque value of the second torque sensor 124 as the control signal. When the first torque sensor 122 returns to normal, the processor 140 may clear (remove) the information about the occurrence of the failure of the first torque sensor 122 from the memory 110 when the vehicle is turned off.

[0065] Thereafter, when the vehicle is turned on (4th key cycle), the processor 140 may read the torque sensor failure information from the memory 110 and use the torque value of the first torque sensor 122 and / or the second torque sensor 124 as the control signal.

[0066] Fig.3 is a flowchart for explaining a method for detecting a failure of a torque sensor for a motor-driven power steering system according to the embodiment of the present disclosure.

[0067] Referring to Fig. 3, when the vehicle is turned on (S302), the processor 140 identifies the failure history of the first torque sensor 122 and the second torque sensor 124 from the torque sensor failure information stored in the memory 110 (S304).

[0068] If the identification result in step S304 indicates that both the first torque sensor 122 and the second torque sensor 124 are normal (S306), the processor 140 selects one of the first torque sensor 122 and the second torque sensor 124 and detects the failures of the first torque sensor 122 and the second torque sensor 124 while using the selected torque sensor for the control process (S308). For simplicity, the following description assumes that the first torque sensor 122 is used first when both the first torque sensor 122 and the second torque sensor 124 are normal. That is, the processor 140 can use the first torque value of the first torque sensor 122 as the control signal.A detailed description of a method by which the processor 140 detects whether the first torque sensor 122 and the second torque sensor 124 are failing is provided with reference to FIG. Fig. 4 described.

[0069] If the failure detection result in step S308 indicates that the first torque sensor 122 is failing (S310), the processor 140 detects the failure of the second torque sensor 124 while using the second torque sensor 124 for the control process (S312). In this case, the processor 140 may use the second torque value of the second torque sensor 124 as the control signal. Furthermore, the processor 140 may calculate the second difference indicating a difference between the column torque value of the second main torque signal of the second torque sensor 124 and the column torque value of the second sub-torque signal of the second torque sensor 124.If the condition in which the second difference is greater than the first reference torque value and equal to or less than the second reference torque value is maintained for the first reference time or longer, or if the condition in which the second difference is greater than the second reference torque value is maintained for the second reference time or longer, the processor 140 may diagnose the second torque sensor 124 with a failure.

[0070] If the result of the error detection in step S312 indicates that the second torque sensor 124 has failed (S314), the processor 140 is switched to the limp home mode or the manual mode (S316).

[0071] Thereafter, when the vehicle is stopped (S318), the processor 140 updates the information about the torque sensor failure (S320). That is, the processor 140 may store the information about the occurrence of failures of the first torque sensor 122 and the second torque sensor 124 in the memory 110. If the torque sensor that has no failure history fails, the processor 140 may also store the failure information about the torque sensor that failed in the memory 110. If the torque sensor with a past failure history is restored to normal during vehicle operation, the processor 140 may also delete the failure history of the corresponding torque sensor stored in the memory 110.

[0072] In the case where the identification result in step S304 indicates that the first torque sensor 122 has the error history (S322), the processor 140 executes step S314.

[0073] If the identification result in step S304 indicates that the second torque sensor 124 has a failure history (S324), the processor 140 detects the failure of the first torque sensor 122 while using the first torque sensor 122 for the control process (S326). In this case, the processor 140 may calculate the first difference between the column torque value of the first main torque signal of the first torque sensor 122 and the column torque value of the first sub-torque signal of the first torque sensor 122.If the condition in which the first difference is greater than the preset first reference torque value and equal to or less than the preset second reference torque value is maintained for the first reference time or longer, or if the condition in which the first difference is greater than the second reference torque value is maintained for the second reference time or longer, the processor 140 may diagnose the first torque sensor 122 with a failure.

[0074] If the result of the failure detection in step S326 indicates that the first torque sensor 122 fails (S328), the processor 140 executes step S316.

[0075] As described above, when the vehicle is turned on, the processor 140 may initially use the first torque sensor 122 (or the second torque sensor 124) for the control process between the normal first torque sensor 122 and the normal second torque sensor 124. If the first torque sensor 122 fails, the processor 140 may perform the control process using the torque signal from the second torque sensor 124. Thereafter, when the vehicle is turned off, the processor 140 may store the fault information about the failed first torque sensor 122 in the memory 110.

[0076] Thereafter, when the vehicle is restarted, the processor 140 may read the torque sensor failure information from the memory 110 and perform the control process using the torque sensor that has not experienced a failure in the past, even though both the first torque sensor 122 and the second torque sensor 124 are currently normal. That is, because the first torque sensor 122 fails, the processor 140 may perform the control process using the second torque sensor 124. If the second torque sensor 124 fails, the processor 140 may diagnose the first torque sensor 122 and the second torque sensor 124 as failed and operate in the manual mode.

[0077] If the result of detecting whether the torque sensor with the past failure history fails during the current key cycle indicates that the corresponding torque sensor has no failure, the processor 140 may also clear the failure history of the corresponding torque sensor stored in the memory 110 when the vehicle is turned off.

[0078] Fig. 4 is a flowchart for explaining a method for detecting a failure of a torque sensor according to the embodiment of the present disclosure.

[0079] With reference to Fig.4, the processor 140 detects whether the first torque sensor 122 and the second torque sensor 124 are failing based on the main torque signals and the sub-torque signals of the first torque sensor 122 and the second torque sensor 124 (S402). That is, the processor 140 may calculate the first difference indicating the difference between the column torque value of the first main torque signal of the first torque sensor 122 and the column torque value of the first sub-torque signal of the first torque sensor 122.If the condition where the first difference is greater than the preset first reference torque value and equal to or less than the preset second reference torque value is maintained for the first reference time or longer, or if the condition where the first difference is greater than the second reference torque value is maintained for the second reference time or longer, the processor 140 may diagnose the first torque sensor 122 with a fault. Furthermore, the processor 140 may calculate the second difference, which indicates the difference between the column torque value of the second main torque signal of the second torque sensor 124 and the column torque value of the second sub-torque signal of the second torque sensor 124.Thereafter, if the condition in which the second difference is greater than the first reference torque value and equal to or less than the second reference torque value is maintained for the first reference time or longer, or if the condition in which the second difference is greater than the second reference torque value is maintained for the second reference time or longer, the processor 140 may diagnose a failure of the second torque sensor 124.

[0080] If the detection result in step S402 indicates that both the first torque sensor 122 and the second torque sensor 124 are normal (S404), the processor 140 compares the first torque value of the first torque sensor 122 and the second torque value of the second torque sensor 124 (S408) and determines whether the comparison result is normal (S408). The processor 140 may calculate the first torque value based on the column torque value of the first main torque signal of the first torque sensor 122 and the column torque value of the first sub-torque signal of the first torque sensor 122, and calculate the second torque value based on the column torque value of the second main torque signal of the second torque sensor 124 and the column torque value of the second sub-torque signal of the second torque sensor 124.In this case, the processor 140 may calculate the average of the column torque value of the first main torque signal and the column torque value of the first sub-torque signal as the first torque value, and calculate the average of the column torque value of the second main torque signal and the column torque value of the second sub-torque signal as the second torque value. Then, the processor 140 may calculate the third difference, which is the difference between the first torque value and the second torque value, and determine whether the state where the third difference is greater than the third reference torque value and equal to or less than the fourth reference torque value is maintained for the third reference time or longer, or the state where the third difference is greater than the fourth reference torque value is maintained for the fourth reference time or longer.If the determination result indicates that the state in which the third difference is greater than the third reference torque value and equal to or less than the fourth reference torque value is maintained for the third reference time or longer, or the state in which the third difference is greater than the fourth reference torque value is maintained for the fourth reference time or longer, the processor 140 may determine that the first torque sensor 122 or the second torque sensor 124 is abnormal.

[0081] When the determination result in step S408 indicates that the result of comparison of the first torque value and the second torque value is normal, the processor 140 uses either the first torque sensor 122 or the second torque sensor 124 for the control process (S410).

[0082] If the determination result in step S406 indicates that the result of comparing the first torque value and the second torque value is abnormal, the processor 140 applies the electric current to the motor 130 (S412) and measures the amount of change in the first torque of the first torque sensor 122 and the amount of change in the second torque of the second torque sensor 124 (S414). In this case, the processor 140 may apply the electric current to the motor 130 based on a preset electric current magnitude and electric current application time to provide a small amount of vibration to the driver. The processor 140 may measure the amount of change in the first torque of the first torque sensor 122 and the amount of change in the second torque of the second torque sensor 124 in accordance with the electric current application.

[0083] When step S414 is executed, the processor 140 determines whether the first torque sensor 122 is failing based on the amount of change in the first torque, and finally detects whether the second torque sensor 124 is failing based on the amount of change in the second torque (S416). That is, if the amount of change in the first torque changes, the processor 140 can determine that the first torque sensor 122 is normal. If the amount of change in the first torque does not vary, the processor 140 can diagnose a failure of the first torque sensor 122. If the amount of change in the second torque varies, the processor 140 can also determine that the second torque sensor 124 is normal. If the amount of change in the second torque does not vary, the processor 140 can diagnose a failure of the second torque sensor 124.

[0084] If the detection result in step S402 indicates that the first torque sensor 122 fails (S418), the process uses the second torque sensor 124 for the control process (S420).

[0085] If the detection result in step S402 indicates that the second torque sensor 124 fails (S422), the process uses the first torque sensor 122 for the control process (S424).

[0086] As described above, the torque sensor failure detection apparatus and method for a motor-driven power steering system according to one aspect of the present disclosure can detect whether the first torque sensor and the second torque sensor are failing based on the main torque signals and the sub-torque signals of the first torque sensor and the second torque sensor. If the detection result indicates that the first torque sensor and the second torque sensor are normal, the apparatus and method can compare the first torque value of the first torque sensor and the second torque value of the second torque sensor and again detect whether the first torque sensor and the second torque sensor are failing.Therefore, it is possible to normally detect the failure of the torque sensor when the torque signal is transmitted within the normal range set for failure detection even though the torque sensor is damaged by external environmental factors. Therefore, the present disclosure can solve the problem of self-rotation that occurs when a fixed torque value is output within a normal range. Furthermore, the present disclosure can improve stability of the vehicle and the driver.

[0087] The torque sensor failure detection apparatus and method for a motor-driven power steering system according to one aspect of the present disclosure can store the failure information about the torque sensor that fails during the current operation of the vehicle and then operate the torque sensor used as a redundancy based on the torque sensor failure information stored in the previous cycle when the vehicle is turned on again, thereby making it possible to effectively cope with the occurrence of the torque sensor failure.

Claims

[1] A device for detecting a failure of a torque sensor for a motor-driven power steering system, the device comprising: a memory (110); Torque sensors comprising a first torque sensor (122) and a second torque sensor (124); and a processor (140) connected to the memory (110) and the torque sensor, wherein the processor (140) detects whether the first torque sensor (122) and the second torque sensor (124) fail based on main torque signals and sub-torque signals from the first torque sensor (122) and the second torque sensor, wherein the processor (140) compares a first torque value of the first torque sensor (122) and a second torque value of the second torque sensor (124) in the event that the detection result indicates that the first torque sensor (122) and the second torque sensor (124) are normal, wherein the processor (140) measures the amount of change in the first torque of the first torque sensor (122) and the amount of change in the second torque of the second torque sensor (124) by applying electric current to a motor if the comparison result is abnormal, and wherein the processor (140) finally detects whether the first torque sensor and the second torque sensor (124) fail based on the amount of change in the first torque and the amount of change in the second torque, wherein the processor (140) calculates a first difference between a column torque value of the first main torque signal of the first torque sensor (122) and a column torque value of the first sub-torque signal of the first torque sensor (122), wherein the processor (140) diagnoses the first torque sensor (122) with a fault if a condition in which the first difference is greater than a preset first reference torque value and equal to or less than a preset second reference torque value is maintained for a first reference time or longer, or if a condition in which the first difference is greater than the second reference torque value is maintained for a second reference time or longer. [2] Device according to claim 1, characterized byin that the processor (140) calculates a second difference between a column torque value of a second main torque signal of the second torque sensor (124) and a column torque value of a second sub-torque signal of the second torque sensor (124), wherein the processor (140) diagnoses the second torque sensor (124) with a fault if a state in which the second difference is greater than the first reference torque value and equal to or less than the second reference torque value is maintained for the first reference time or longer, or if a state in which the second difference is greater than the second reference torque value is maintained for the second reference time or longer. [3] Device according to claim 2, characterized by that the first reference torque value is smaller than the second reference torque value and the first reference time is longer than the second reference time. [4] Device according to one of claims 1 to 3, characterized by in that the processor (140) calculates the first torque value based on a column torque value of a first main torque signal of the first torque sensor (122) and a column torque value of a first sub-torque signal of the first torque sensor (122), wherein the processor (140) calculates the second torque value based on a column torque value of a second main torque signal of the second torque sensor (124) and a column torque value of a second sub-torque signal of the second torque sensor (124). [5] Device according to claim 4, characterized bythat the processor (140) calculates a third difference which is a difference between the first torque value and the second torque value, wherein the processor (140) determines that the first torque sensor (122) or the second torque sensor (124) is abnormal if a state in which the third difference is greater than a preset third reference torque value and equal to or less than a preset fourth reference torque value is maintained for a third reference time or longer, or if a state in which the third difference is greater than the fourth reference torque value is maintained for a fourth reference time or longer. [6] Device according to claim 5, characterized by that the third reference torque value is smaller than the fourth reference torque value and the third reference time is longer than the fourth reference time. [7] Device according to one of claims 1 to 6, characterized bythat the processor (140) determines that the first torque sensor (122) is normal if the amount of change in the first torque changes, wherein the processor (140) determines that the first torque sensor (122) is failing if the amount of change in the first torque does not change, wherein the processor (140) determines that the second torque sensor (124) is normal if the amount of change in the second torque varies, and wherein the processor (140) determines that the second torque sensor (124) is failing if the amount of change in the second torque does not change. [8] Device according to one of claims 1 to 7, characterized bythat when a vehicle is turned on, the processor (140) selects a normal torque sensor between the first torque sensor (122) and the second torque sensor (124) based on torque sensor failure information stored in the memory (110) and detects failures of the normal torque sensor and the other torque sensor while controlling the engine using the torque signal from the selected normal torque sensor, and wherein when the vehicle is turned off, the processor (140) updates the torque sensor failure information stored in the memory (110) based on the result of the failure detection. [9] Device according to claim 8, characterized by that the processor (140) determines whether the other torque sensor is normal based on the torque sensor failure information if a failure of the normal torque sensor is diagnosed, wherein the processor (140) uses the other torque sensor for a control process if the other torque sensor is normal, and wherein the processor (140) changes a mode to a limp home mode or a manual mode when the other torque sensor fails. [10] A method for detecting a failure of a torque sensor for a motor-driven power steering system, the method comprising: Selecting a normal torque sensor between a first torque sensor and a second torque sensor (124) by a processor (140) based on torque sensor failure information stored in a memory (110) when a vehicle is turned on; detecting failures of the normal torque sensor and the other torque sensor by the processor (140) during control of an engine using a torque signal from the selected normal torque sensor; and Updating the torque sensor failure information stored in the memory (110) by the processor (140) based on the result of the failure detection when the vehicle is parked, wherein, upon failure detection, the processor (140) detects whether the first torque sensor (122) and the second torque sensor (124) are failing based on main torque signals and sub-torque signals of the first torque sensor (122) and the second torque sensor (124), the processor (140) compares a first torque value of the first torque sensor (122) and a second torque value of the second torque sensor (124) if the detection result indicates that the first torque sensor and the second torque sensor (124) are normal,the processor (140) measures the amount of change in the first torque of the first torque sensor (122) and the amount of change in the second torque of the second torque sensor (124) by applying an electric current to a motor if the comparison result is abnormal, and the processor (140) finally detects whether the first torque sensor (122) and the second torque sensor (124) are failing based on the amount of change in the first torque and the amount of change in the second torque. [11] Method according to claim 10, characterized bythat the processor (140), upon detecting the error, determines that the first torque sensor (122) is normal if the amount of change in the first torque varies, the processor (140) determines that the first torque sensor (122) is failing if the amount of change in the first torque does not vary, the processor (140) determines that the second torque sensor (124) is normal if the amount of change in the second torque varies, and the processor (140) determines that the second torque sensor (124) is failing if the amount of change in the second torque does not vary. [12] Method according to one of claims 10 to 11, characterized bythat the processor (140) determines whether the other torque sensor is normal upon detecting the failure based on the torque sensor failure information, if a failure of the normal torque sensor is diagnosed, the processor (140) uses the other torque sensor for a control process if the other torque sensor is normal, and the processor (140) changes a mode to an emergency mode or a manual mode if the other torque sensor fails.

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