VEHICLE STEER-BY-WIRE SYSTEM AND CONTROL METHOD THEREFOR

Abstract

An electronic steering system for a vehicle is provided. The system includes an input module configured to receive a steering command angle from a cooperative control unit, a steering angle sensor configured to detect a steering angle, a memory, and a processor operatively coupled to the input module, the steering angle sensor, and the memory. The processor is configured to, when a cooperative control command angle is input from the input module, calculate a steering angle offset and a command angle offset, and then perform steering angle position control with respect to the cooperative control command angle by sequentially stepping down the steering angle offset and the command angle offset to output a pinion angle.

Description

BACKGROUND AREA

[0001] Example embodiments of the present disclosure relate to a vehicle steer-by-wire system and a control method therefor. DISCUSSION OF THE BACKGROUND

[0002] In general, power steering systems have been developed and used in vehicle steering devices to facilitate driving operation by assisting the driver's steering wheel maneuverability, and such power steering systems have been developed and used as hydraulic systems that use hydraulic pressure, electro-hydraulic systems that use both hydraulic pressure and the electric power of a motor, and electric systems that use only the electric power of a motor.

[0003] In recent years, an electronic steering system in the form of steer-by-wire (SBW) has been developed and deployed, which eliminates the need for a mechanical connection such as a steering column, universal joint, and pinion shaft between a steering wheel and vehicle wheels and uses electrical signals to drive a motor connected to a rack and pinion to steer a vehicle.

[0004] Such an electronic steering system may include a steering wheel for the driver's steering operation, a reaction force motor installed on one side of the steering wheel to provide a reaction force torque according to the rotation of the steering wheel, a steering motor connected to a rack to perform a steering operation, sensors for detecting a steering angle, vehicle speed, and steering wheel torque, and an ECU for driving the steering motor and the reaction force motor according to electrical signals input from the sensors.

[0005] Such an SBW type electronic steering system has the advantages of reducing driver injuries caused by mechanical parts in the event of a vehicle collision due to the absence of mechanical linkages, reducing the weight of a vehicle and unnecessary energy consumption during steering by reducing mechanical linkages, and achieving ideal steering behavior through ECU programming, and is increasingly being used.

[0006] The SBW type electronic steering system has the advantage of eliminating the mechanical linkage structure of the conventional steering system, thereby increasing the design freedom of steering system configurations, improving fuel efficiency, and eliminating interference reflected from the vehicle's wheels.

[0007] However, if an emergency situation occurs during autonomous driving, such as the sudden threat of a collision or other accident, a vehicle must control its speed or steering to avoid the emergency. To avoid such an emergency situation, decelerating the vehicle is effective, but driver steering may also be required. For example, if the autonomous driving system fails, a vehicle may deviate from the driver's intentions, so the driver's steering must be considered.

[0008] In other words, in SBW systems, the steering angle of the steering wheel and the pinion angle of the wheel are affected by the software variable transmission ratio (VGR) depending on the vehicle speed and mode, so the position control command of the pinion angle is not always consistent and often changes depending on the vehicle speed and steering angle.

[0009] Therefore, in an SBW autonomous driving system, the pinion angle follows the steering angle, and the steering angle must match the cooperative control command angle of an advanced driver assistance system (ADAS) to enable rapid driver change.

[0010] However, when calculating the autonomous driving command with the pinion angle, a difference with the steering angle occurs, resulting in a position difference between the steering angle and the pinion angle, which makes accurate cooperative control difficult when performing the cooperative control command angle of ADAS.

[0011] The background of the present disclosure is disclosed in Korean Unexamined Patent Publication No. 10-2022-0064012 (published on May 18, 2022 under the title “Steer-By-Wire System Steering Control Device and Method”).

[0012] The above-described information disclosed in the background of the present disclosure is provided only to facilitate understanding of the background of the present disclosure and may therefore contain information that is not prior art. SUMMARY

[0013] Various embodiments relate to a steer-by-wire (SBW) type electronic steering system for a vehicle and a control method therefor, in which an offset from a steering angle and an offset from a variable transmission ratio (VGR) command angle are calculated with respect to a cooperative control command angle, and then a ramp-down gain is adjusted to match the cooperative control command angle with a steering position control angle and a pinion angle to switch to a steering position control mode.

[0014] The problem to be solved by the present disclosure is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

[0015] In one embodiment, an electronic steering system for a vehicle comprises: an input module configured to receive a steering command angle from a cooperative control unit; a steering angle sensor configured to detect a steering angle; a memory; and a processor operatively coupled to the input module, the steering angle sensor, and the memory, wherein the processor is configured to, when a cooperative control command angle is input from the input module, calculate a steering angle offset and a command angle offset, and then perform steering angle position control with respect to the cooperative control command angle by sequentially stepping down the steering angle offset and the command angle offset to output a pinion angle.

[0016] The processor may be configured to sequentially ramp down and apply the steering angle offset during feedback of an output value for the steering angle position control.

[0017] The processor may be configured to sequentially ramp down the steering angle offset and the desired angle offset and apply the ramped offsets to an output value of the steering angle position control to output the pinion angle.

[0018] The steering angle offset may be a difference between the cooperative steering command angle and the steering angle, and the command angle offset may be a difference between the VGR command angle and the cooperative steering command angle.

[0019] The processor can be configured to output a pinion angle when the steering angle is input by tuning VGR.

[0020] In one embodiment, a method for controlling an electronic steering system for a vehicle with a processor comprises: determining whether a cooperative steering command angle is input from an input module; calculating a steering angle offset and a command angle offset when the cooperative steering command angle is input; and outputting a pinion angle by performing steering angle position control with respect to the cooperative steering command angle while sequentially stepping down the steering angle offset and the command angle offset.

[0021] Outputting the pinion angle may include sequentially ramping down and applying the steering angle offset while providing an output value for the steering angle position control.

[0022] Outputting the pinion angle may include sequentially stepping down the steering angle offset and the command angle offset and applying the stepped down offsets to a steering angle position control output value to output the pinion angle.

[0023] The steering angle offset may be a difference between the cooperative steering command angle and the steering angle, and the command angle offset may be a difference between the VGR command angle and the cooperative steering command angle.

[0024] The method may further comprise that when the steering angle is input, a pinion angle is output by adjusting VGR.

[0025] According to embodiments of the present disclosure, in the steer-by-wire (SBW) type electronic steering system for a vehicle and its control method, an autonomous driving command may be executed by calculating the steering angle offset and the pinion angle offset with respect to the cooperative control command angle, and then adjusting the ramp down gain to match the cooperative control command angle with the position control angle and the pinion angle, and switching to the steering angle position control mode.

[0026] However, the effects that can be achieved by the present disclosure are not limited to the effects described above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the following description of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing an electronic steering system for a vehicle according to an embodiment of the present disclosure; Fig. 2 is a logic diagram for performing steering angle position control in the electronic steering system for a vehicle according to an embodiment of the present disclosure; and Fig. 3 is a flowchart illustrating a method of controlling an electronic steering system for a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0027] 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.

[0028] The method according to the 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.

[0029] 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 deployed 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.

[0030] 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 any type of digital computer. 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 read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM), as well as any other known computer-readable medium. A processor and memory may be supplemented by or integrated with dedicated logic circuitry.

[0031] 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.

[0032] Non-transferable, 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.

[0033] 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 into a sub-combination or a variation of a sub-combination.

[0034] 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 example implementations described above is required in all example implementations, 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.

[0035] 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 violating the spirit and scope of the claims and their equivalents.

[0036] 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.

[0037] In the following description of the embodiments of the present disclosure, a detailed description of 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.

[0038] In the present disclosure, the individual components are distinguished from one another to clarify the 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 a plurality of hardware or software units. Unless otherwise stated, such integrated or distributed embodiments are also within the scope of the present disclosure.

[0039] 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.

[0040] 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.

[0041] In the following description of the embodiments of the present disclosure, a detailed description of 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.

[0042] 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 "with" another component, this may refer to the inclusion of another component, not its exclusion, unless expressly described to the contrary.

[0043] In this disclosure, the terms "first," "second," etc., are used only to distinguish between the individual components and do not limit the order or importance of the 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.

[0044] In this disclosure, the individual components are distinguished from one another to clarify their 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 a plurality of hardware or software units. Unless otherwise stated, such integrated or distributed embodiments are also within the scope of this disclosure.

[0045] 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, exemplary embodiments that include additional components in addition to the components described in the various embodiments are also within the scope of the present disclosure.

[0046] Fig. 1 is a block diagram illustrating an electronic steering system for a vehicle according to an embodiment of the present disclosure, and Fig. 2 is a logic diagram for performing steering angle position control in the electronic steering system for a vehicle according to an embodiment of the present disclosure.

[0047] As in Fig. 1, the electronic steering system for a vehicle according to the present embodiment may include a steering wheel drive module 50 and a road wheel drive module 60, as well as an input module 10, a steering angle sensor 20, a memory 30, and a processor 40.

[0048] The input module 10 can receive a cooperative control command angle from a cooperative control unit via the on-board CAN communication.

[0049] The input module 10 can receive not only the cooperative steering command angle from the cooperative control unit, such as an ADAS, but also the operating state of the steering wheel drive module 50 and the road wheel drive module 60 as well as the vehicle speed and the driving mode from an on-vehicle electronic control unit.

[0050] The steering angle sensor 20 can detect a steering angle of the steering wheel.

[0051] The steering wheel drive module 50 can generate a reaction torque according to the rotation of the steering wheel to impart a steering feel, and can also drive the steering wheel when cooperative control is performed by autonomous driving.

[0052] The wheel drive module 60 can drive and steer road wheels according to a pinion angle, which is a target angle.

[0053] The memory 30 can store data relating to an executable program for operating the electronic steering system, and the stored information can be independently selected by the processor 40 as needed.

[0054] In other words, memory 30 stores various types of data generated during the execution of an operating system or an application (program or applet) for operating the electronic steering system. In this context, memory 30 refers to non-volatile memory, which retains stored information even when power is not supplied to it, and volatile memory, which requires power to retain stored information. Furthermore, memory 30 can perform a function of temporarily or permanently storing data processed by processor 40.

[0055] Here, the memory 30 may include magnetic storage media or flash storage media in addition to volatile memories that require energy to maintain the stored information, but the scope of the present disclosure is not limited thereto.

[0056] The processor 40 is operatively coupled to the input module 10, the steering angle sensor 20, the steering wheel drive module 50, the road wheel drive module 60, and the memory 30 to copy and execute various programs stored in the memory 30 to control the overall operation of the electronic steering system and to perform various operations.

[0057] While the processor 40 is described herein as only one CPU, it may be implemented using a plurality of CPUs (or DSPs, SoCs, etc.) to control the steering wheel drive module 50 and the road wheel drive module 60, respectively.

[0058] In various embodiments, processor 40 may be implemented as a digital signal processor (DSP), a microprocessor, or a timing control unit (TCON) that processes digital signals. However, the processor is not limited to these; rather, processor 40 may include or be defined as one or more central processing units (CPU), a microcontroller unit (MCU), a microprocessing unit (MPU), a controller, an application processor (AP), a communication processor (CP), or an ARM processor. Processor 40 may also be implemented as a system on chip (SoC) embedded in the processing algorithm, as a large-scale integration (LSI), or as a field-programmable gate array (FPGA).

[0059] In other words, the processor 40 may be configured to output a steering angle offset and a command angle offset when a cooperative control command angle is input from the input module, and then perform steering angle position control for the cooperative control command angle while sequentially stepping down the steering angle offset and the command angle offset to output a pinion angle.

[0060] The steering angle offset can be calculated as a difference between the cooperative control command angle and the steering angle, and the command angle offset can be calculated as a difference between the VGR command angle and the cooperative control command angle.

[0061] A more detailed description is given with reference to Fig. 2.

[0062] The processor 40 may sequentially ramp down and apply the steering angle offset while feedbacking an output value for the steering angle position control with respect to the cooperative control command angle.

[0063] This means that by sequentially applying a ramp-down gain from 1 to 0, the steering angle offset can be eliminated so that the cooperative control command angle and the steering angle are matched.

[0064] In addition, the processor 40 may sequentially step down the steering angle offset and the command i-angle offset and apply the stepped down offsets to the output value of the steering angle position control to output the pinion angle.

[0065] In other words, by sequentially applying a ramp-down gain from 1 to 0, the steering angle offset and the command angle offset can be controlled so that the cooperative steering command angle and the pinion angle are matched.

[0066] In this way, the steering angle offset and the command angle offset are sequentially eliminated to enter the steering angle position control mode, so that the pinion angle can be controlled by the steering angle position control without deviation of the positions of the steering angle and the pinion angle to execute an autonomous driving command.

[0067] On the other hand, when the steering angle is input from the steering angle sensor 20 by the driver's steering movement, the processor 40 can output the pinion angle by VGR tuning depending on the vehicle speed and the driving mode.

[0068] As described above, in the steer-by-wire type electronic steering system for a vehicle according to an embodiment of the present disclosure, the steering angle offset and the pinion angle offset may be calculated with respect to the cooperative control command angle, and then the ramp-down gain is adjusted so that the cooperative control command angle and the position control angle are matched to switch to the steering angle position control mode to execute an autonomous driving command.

[0069] Fig. 3 is a flowchart illustrating a method of controlling an electronic steering system for a vehicle according to an embodiment of the present disclosure.

[0070] As in Fig. 3, in the method of controlling the electronic steering system for a vehicle according to the present embodiment, the processor 40 first executes an executable program embedded in the memory 30 and determines whether a cooperative control command angle is input from the cooperative control device via the input module 10 (S10).

[0071] As a result of the determination in S10, when the cooperative steering command angle is input from the cooperative control device such as an ADAS for autonomous driving, the processor 40 calculates the steering angle offset and the command angle offset of a vehicle (S20).

[0072] The steering angle offset can be calculated as a difference between the cooperative control command angle and the steering angle, and the command angle offset can be calculated as a difference between the VGR command angle and the cooperative control command angle.

[0073] After calculating the steering angle offset and the command offset in S20, the processor performs steering angle position control with respect to the cooperative control command angle by sequentially decreasing the steering angle offset and the command angle offset (S30).

[0074] As in Fig. 2, the processor 40 may sequentially ramp down and apply the steering angle offset while providing feedback of an output value for the steering angle position control relative to the cooperative steering command angle.

[0075] This means that by sequentially applying a ramp-down gain from 1 to 0, the steering angle offset can be eliminated so that the cooperative control command angle and the steering angle are matched.

[0076] In addition, the processor 40 may sequentially ramp down the steering angle offset and the target angle offset and apply the ramped down offsets to the output value of the steering angle position control to output the pinion angle.

[0077] In other words, by sequentially applying a ramp-down gain from 1 to 0, the steering angle offset and the target angle offset can be controlled so that the cooperative steering command angle and the pinion angle are matched.

[0078] In this way, the processor 40 can control the steering wheel drive module by sequentially eliminating the steering angle offset and the command angle offset to switch to the steering angle position control mode to perform steering angle position control for the cooperative control command angle, and control the steering wheel drive module 50 by outputting the pinion angle which is the result of the steering angle position control (S40).

[0079] On the other hand, as a result of the determination in S10, the processor 40 performs VGR adjustment according to the vehicle speed and the driving mode (S50) when the steering angle obtained by the driver's steering operation is input from the steering angle sensor 20 without the input of the cooperative steering command angle.

[0080] After performing the VGR tuning in step S50, the processor 40 outputs the pinion angle based on the VGR tuning (S60).

[0081] As described above, according to embodiments of the present disclosure, in the steer-by-wire (SBW) type electronic steering system for a vehicle and its control method, an autonomous driving command can be executed by calculating the steering angle offset and the pinion angle offset with respect to the cooperative control command angle, and then adjusting the ramp down gain to match the cooperative control command angle with the position control angle and the pinion angle, and switching to the steering angle position control mode. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2022-0064012

[0011]

Claims

[1] Electronic steering system for a vehicle, the system comprising: an input module configured to receive a steering command angle from a cooperative control unit; a steering angle sensor configured to detect a steering angle; a memory; and a processor operatively coupled to the input module, the steering angle sensor, and the memory, the processor configured to, when a cooperative steering command angle is input from the input module, calculate a steering angle offset and a command angle offset, and then perform steering angle position control with respect to the cooperative steering command angle by sequentially stepping down the steering angle offset and the command angle offset to output a pinion angle. [2] The electronic steering system of claim 1, wherein the processor is configured to sequentially ramp down and apply the steering angle offset during feedback of an output value for the steering angle position control. [3] The electronic steering system of claim 1 or 2, wherein the processor is configured to sequentially ramp down the steering angle offset and the command angle offset and apply the ramped down offsets to an output value of the steering angle position controller to output the pinion angle. [4] The electronic steering system according to any one of claims 1 to 3, wherein the steering angle offset is a difference between the cooperative control command angle and the steering angle, and the command angle offset is a difference between the VGR command angle and the cooperative control command angle. [5] The electronic steering system according to any one of claims 1 to 4, wherein the processor is configured to output a pinion angle by adjusting VGR upon input of the steering angle. [6] A method for controlling an electronic steering system for a vehicle with a processor, the method comprising: Determine whether a cooperative control command angle is input from an input module; Calculating a steering angle offset and a command angle offset if the cooperative steering command angle is input; and Outputting a pinion angle by performing steering angle position control with respect to the cooperative control command angle while sequentially driving down the steering angle offset and the command angle offset. [7] The method of claim 6, wherein outputting the pinion angle comprises sequentially ramping down and applying the steering angle offset while feedbacking an output value for the steering angle position control. [8] The method of claim 6 or 7, wherein outputting the pinion angle comprises sequentially stepping down the steering angle offset and the command angle offset and applying the stepped down offsets to an output value of the steering angle position controller to output the pinion angle. [9] The method of any one of claims 6 to 8, wherein the steering angle offset is a difference between the cooperative control command angle and the steering angle, and the command angle offset is a difference between the VGR command angle and the cooperative control command angle. [10] The method according to any one of claims 6 to 9, further comprising, upon input of the steering angle, outputting a pinion angle by tuning VGR.

Images