Vehicle steer-by-wire system and control method thereof

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 operably coupled to the input module, the steering angle sensor, and the memory, where the processor is configured to: calculate a steering angle offset and a command angle offset when a cooperative control command angle is input from the input module, and then implement a steering angle position control with respect to the cooperative control command angle by sequentially gradually reducing the steering angle offset and the command angle offset to output a pinion angle. The present disclosure implements an automatic driving command by calculating a steering angle offset and a pinion angle offset, matching a cooperative control command angle with a position control angle and a pinion angle, and switching to a steering angle position control mode.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to a vehicle steer-by-wire system and a control method thereof. Background Art

[0002] Generally, in vehicle steering devices, power steering systems have been developed and applied to provide convenience in driving operations by assisting the driver's steering wheel maneuverability, wherein such power steering systems have been developed and applied as hydraulic systems using hydraulic pressure, electro-hydraulic systems using hydraulic pressure and electric power from an engine, and electric systems using only electric power from an engine.

[0003] In recent years, electronic steering systems have been developed and applied in the form of Steer-By-Wire (SBW), which eliminate mechanical connections (such as steering columns, universal joints, and pinion shafts between steering wheels and vehicle wheels) and steer the vehicle by controlling the drive of an engine connected to a rack through electrical signals.

[0004] Such an electronic steering system may include a steering wheel for a 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 achieve steering operation, a sensor for detecting the torque, steering angle, and vehicle speed of the steering wheel, and an ECU for driving the steering motor and the reaction force motor according to electrical signals input from the sensors.

[0005] This SBW type electronic steering system has the advantages of reducing driver injuries caused by mechanical components in the event of a vehicle collision due to the lack of mechanical connections, reducing vehicle weight and unnecessary energy consumption during steering operations due to the reduction of mechanically connected parts, and achieving ideal steering performance through ECU programming. Therefore, it is being increasingly used.

[0006] Therefore, the SBW type electronic steering system has the advantage of eliminating the mechanical connection structure of the conventional steering system, thereby increasing the layout freedom of the steering system configuration, improving fuel efficiency, and eliminating interference from reverse input from the vehicle wheels.

[0007] On the other hand, if an emergency situation arises during automated driving, such as a sudden risk of a collision or other accident, the vehicle must implement speed or steering control to avoid the emergency. While deceleration is effective in avoiding such an emergency, the driver may need to steer if necessary. For example, if the automated driving system malfunctions, the vehicle may deviate from the driver's intended direction, making steering inherently necessary.

[0008] In other words, in the SBW system, the steering angle of the steering wheel and the pinion angle of the wheel are affected by the software variable gear ratio (VGR) of the vehicle speed and mode, so the position control command of the pinion angle is not always consistent and changes frequently according to the vehicle speed and steering angle.

[0009] Therefore, in the case of an SBW system for autonomous driving, the pinion angle follows the steering angle, and the steering angle needs to be positioned using a cooperative control command angle of an advanced driver assistance system (ADAS) to achieve fast driver switching.

[0010] However, when calculating the autonomous driving command with the pinion angle, a difference is generated in the steering angle, resulting in a position difference between the steering angle and the pinion angle, making it difficult to implement precise cooperative control when implementing the ADAS cooperative control command angle.

[0011] Background art of the present disclosure is disclosed in Korean Unexamined Patent Publication No. 10-2022-0064012 (published on May 18, 2022, and entitled “Steering Control Apparatus and Method for Steer-by-Wire System”).

[0012] The above information disclosed in the background of the present disclosure is only intended to provide a better understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art. Summary of the Invention

[0013] Various embodiments relate to a steer-by-wire (SBW) type electronic steering system for a vehicle and a control method thereof, wherein an offset of a steering angle and an offset of a variable gear ratio (VGR) command angle relative to a cooperative control command angle are calculated, and then a gradually decreasing 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] Problems to be solved by the present disclosure are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

[0015] In one embodiment, an electronic steering system for a vehicle includes: an input module configured to receive a steering command angle from a collaborative control unit; a steering angle sensor configured to detect a steering angle; a memory; and a processor operably connected to the input module, the steering angle sensor, and the memory, wherein the processor is configured to: calculate a steering angle offset and a command angle offset when a collaborative control command angle is input from the input module, and then implement steering angle position control relative to the collaborative control command angle by sequentially and gradually reducing the steering angle offset and the command angle offset to output a pinion angle.

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

[0017] The processor may be configured to sequentially gradually reduce the steering angle offset and the command angle offset, and apply the gradually reduced offset 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 control command angle and the steering angle, and the command angle offset may be a difference between a VGR command angle and the cooperative control command angle.

[0019] The processor may be configured to output a pinion angle by adjusting the VGR after the steering angle is input.

[0020] In one embodiment, a method for controlling an electronic steering system for a vehicle using a processor includes: determining whether a collaborative control command angle is input from an input module; if the collaborative control command angle is input, calculating a steering angle offset and a command angle offset; and outputting a pinion angle by implementing steering angle position control relative to the collaborative control command angle while sequentially and gradually reducing the steering angle offset and the command angle offset.

[0021] The outputting the pinion angle may include sequentially gradually reducing and applying the steering angle offset during feedback of an output value for steering angle position control.

[0022] Outputting the pinion angle may include sequentially gradually reducing the steering angle offset and the command angle offset, and applying the gradually reduced offset to an output value of the steering angle position control to output the pinion angle.

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

[0024] The method may further include outputting a pinion angle by adjusting the VGR after the steering angle is input.

[0025] According to an embodiment of the present disclosure, in a steer-by-wire (SBW) type electronic steering system for a vehicle and a control method thereof, an autonomous driving command can be implemented by calculating a steering angle offset and a pinion angle offset relative to a collaborative control command angle, adjusting a gradually decreasing gain to match the collaborative control command angle with the position control angle and the pinion angle, and switching to a steering angle position control mode.

[0026] However, the effects obtainable by the present disclosure are not limited to the above-mentioned effects, 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

[0027] Figure 1 is a block diagram illustrating an electronic steering system for a vehicle according to an embodiment of the present disclosure;

[0028] Figure 2 is a logic diagram for implementing steering angle position control in an electronic steering system for a vehicle according to an embodiment of the present disclosure; and

[0029] Figure 3 is a flowchart illustrating a control method of an electronic steering system for a vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] The components described in the exemplary embodiments may be implemented by hardware components, including, for example, 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 a combination thereof. At least some of the functions or methods described in the exemplary embodiments may be implemented by software, and the software may be recorded on a recording medium. The components, functions, and methods described in the exemplary embodiments may be implemented by a combination of hardware and software.

[0031] The method according to the exemplary embodiment may be embodied as a program that can be implemented by a computer, and may be realized as various recording media such as a magnetic storage medium, an optical reading medium, and a digital storage medium.

[0032] The various techniques described herein can be implemented as digital electronic circuits, or as computer hardware, firmware, software, or a combination thereof. These techniques can be implemented as computer program products, i.e., computer programs tangibly embodied in information carriers, for example, embodied in machine-readable storage devices (e.g., computer-readable media), or embodied in propagation signals for processing or controlling the operation of data processing devices by data processing devices (e.g., programmable processors, computers, or multiple computers). Computer programs can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including stand-alone programs or modules, components, subroutines, or other units suitable for a computing environment. Computer programs can be deployed to execute on one computer or at one site or distributed on multiple sites and interconnected by a communication network.

[0033] For example, processors suitable for executing computer programs include general-purpose and special-purpose microprocessors, as well as any one or more processors of any type of digital computer. Typically, 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 memory devices for storing instructions and data. Typically, a computer also includes one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or is coupled to receive data from one or more mass storage devices, transfer data to one or more mass storage devices, or perform both on one or more mass storage devices. Examples of information carriers suitable for implementing computer program instructions and data include semiconductor memory devices, for example, magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as compact disc read-only memory (CD-ROMs), digital video disks (DVDs), and magneto-optical media such as optical floppy disks, as well as 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 media. The processor and memory may be supplemented by or integrated into dedicated logic circuitry.

[0034] The processor can run an operating system (OS) and one or more software applications running on the OS. The processor device can also access, store, manipulate, process, and create data in response to the execution of the software. For simplicity, the description of the processor device is used as a singular; however, those skilled in the art will understand that the processor device can include multiple processing elements and / or multiple types of processing elements. For example, the processor device can include multiple processors or include a processor and a controller. In addition, different processing configurations are possible, such as parallel processors.

[0035] Furthermore, 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.

[0036] This specification includes the details of many specific embodiments, but it should be understood that these details do not limit any invention or the content claimed in this specification, but rather describe the features of specific exemplary embodiments. The features described in the context of each exemplary embodiment can be implemented as a combination in a single exemplary embodiment. On the contrary, the various features described in the context of a single exemplary embodiment can be implemented in multiple exemplary embodiments individually or in an appropriate sub-combination. In addition, features can operate in a specific combination and can be initially described as being claimed in the combination, but in some cases, one or more features can be excluded from the claimed combination, and the claimed combination can be changed to a modification of a sub-combination or a sub-combination.

[0037] Similarly, even if operations are described in a particular order in the accompanying drawings, it should not be understood that the operations need to be performed in a particular order or sequentially to obtain the desired results, or that all operations need to be performed. In certain circumstances, multitasking and parallel processing may be advantageous. Furthermore, it should not be understood that the various device components in the exemplary embodiments described above are required to be separated in all exemplary embodiments, and it should be understood that the program components and devices described above can be incorporated into a single software product or can be packaged in multiple software products.

[0038] It should be understood that the exemplary embodiments disclosed herein are illustrative only and are not intended to limit the scope of the invention. It will be apparent to those skilled in the art that various modifications may be made to the exemplary embodiments without departing from the spirit and scope of the claims and their equivalents.

[0039] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein.

[0040] In the following description of the embodiments of the present disclosure, detailed descriptions of known functions and configurations incorporated herein will be omitted when they may make the subject matter of the present disclosure rather unclear. Parts in the drawings that are not related to the description of the present disclosure are omitted, and the same parts are marked with the same reference numerals.

[0041] In this disclosure, components that are distinct from one another are intended to clearly illustrate each feature. However, this does not necessarily mean that the components are separate. In other words, multiple components can be integrated into a single hardware or software unit, or a single component can be distributed across multiple hardware or software units. Therefore, unless otherwise indicated, such integrated or distributed implementations are also included 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 components may be optional components. Therefore, the embodiment consisting of the subset of the components described in an embodiment is also included in the scope of the present disclosure. In addition, the embodiment comprising other components in addition to the components described in the various embodiments is also included in the scope of the present disclosure.

[0043] In the present disclosure, when a component is referred to as being "linked," "coupled," or "connected" to another component, it should be understood that not only a direct connection relationship but also an indirect connection relationship through an intermediate component may be included. In addition, when a component is referred to as "including" or "having" another component, it may mean that the other component is also included rather than excluded, unless explicitly described to the contrary.

[0044] In the present disclosure, unless otherwise specifically stated, the terms first, second, etc. are used only to distinguish one component from another component, and do not limit the order or importance of the components, etc. Therefore, within the scope of the present 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.

[0045] Figure 1 is a block diagram illustrating an electronic steering system for a vehicle according to an embodiment of the present disclosure, and Figure 2 is a logic diagram for implementing steering angle position control in an electronic steering system for a vehicle according to an embodiment of the present disclosure.

[0046] like Figure 1 As shown, the electronic steering system for a vehicle according to an embodiment of the present disclosure may include a steering wheel drive module 50 and a wheel drive module 60 , as well as an input module 10 , a steering angle sensor 20 , a memory 30 , and a processor 40 .

[0047] The input module 10 may receive the cooperative control command angle from the cooperative control unit via the in-vehicle CAN communication.

[0048] Here, the input module 10 may receive not only the cooperative control command angle from a cooperative control unit such as ADAS, but also the operating status of the steering wheel drive module 50 and the wheel drive module 60 as well as the vehicle speed and driving mode from the vehicle electronic control unit.

[0049] The steering angle sensor 20 can detect the steering angle of the steering wheel.

[0050] The steering wheel drive module 50 may generate a reaction torque according to the rotation of the steering wheel to provide a steering feel, and may also drive the steering wheel when cooperative control through autonomous driving is implemented.

[0051] The wheel driving module 60 may drive and steer the wheels according to the pinion angle as a command angle.

[0052] The memory 30 may store data related to executable programs for the operation of the electronic steering system, and the stored information may be independently selected by the processor 40 as needed.

[0053] In other words, the memory 30 stores various data generated during the execution of the operating system or application programs (programs or applets) used to operate the electronic steering system. In this context, the memory 30 refers to both non-volatile memory that retains stored information even when power is not supplied, and volatile memory that requires power to retain stored information. Furthermore, the memory 30 may temporarily or permanently store data processed by the processor 40.

[0054] Here, the memory 30 may include a magnetic storage medium or a flash storage medium in addition to a volatile memory requiring power to maintain stored information, but the scope of the present disclosure is not limited thereto.

[0055] The processor 40 is operably connected to the input module 10, the steering angle sensor 20, the steering wheel drive module 50, the wheel drive module 60 and the memory 30 to copy and execute various programs stored in the memory 30 for controlling the overall operation of the electronic steering system to implement various operations.

[0056] Although the processor 40 is described herein as including only one CPU, it may be implemented to control the steering wheel drive module 50 and the wheel drive module 60 via a plurality of CPUs (or DSPs, SoCs, etc.), respectively.

[0057] In various embodiments, the processor 40 may be implemented as a digital signal processor (DSP) for processing digital signals, a microprocessor, or a time controller (TCON). However, the processor is not limited thereto, but the processor 40 may include or be defined as one or more of a central processing unit (CPU), a microcontroller unit (MCU), a microprocessing unit (MPU), a controller, an application processor (AP), a communication processor (CP), or an ARM processor. The processor 40 may also be implemented as a processing algorithm embedded system on chip (SoC), a large-scale integration (LSI), or a field programmable gate array (FPGA).

[0058] In other words, the processor 40 can be configured to: output the steering angle offset and the command angle offset when the collaborative control command angle is input from the input module, and then implement the steering angle position control for the collaborative control command angle, while sequentially and gradually reducing the steering angle offset and the command angle offset to output the pinion angle.

[0059] Here, the steering angle offset may be calculated as a difference between the cooperative control command angle and the steering angle, and the command angle offset may be calculated as a difference between a VGR command angle and the cooperative control command angle.

[0060] Will refer to Figure 2 Describe in more detail.

[0061] The processor 40 may sequentially gradually reduce and apply the steering angle offset during feedback of the output value of the steering angle position control with respect to the cooperative control command angle.

[0062] In other words, by sequentially applying gradually decreasing gains from 1 to 0, the steering angle offset can be eliminated so that the cooperative control command angle and the steering angle match each other.

[0063] Furthermore, the processor 40 may sequentially gradually reduce the steering angle offset and the command angle offset, and apply the gradually reduced offset to the output value of the steering angle position control to output the pinion angle.

[0064] In other words, by sequentially applying gradually decreasing gains from 1 to 0, the steering angle offset and the command angle offset can be controlled so that the cooperatively controlled command angle and the pinion angle match each other.

[0065] In this way, the steering angle offset and the command angle offset are sequentially eliminated to switch to the steering angle position control mode, so that the pinion angle can be controlled by the steering angle position control without causing the position offset of the steering angle and the pinion angle, thereby implementing the automatic driving command.

[0066] On the other hand, when the steering angle is input from the steering angle sensor 20 by the driver's steering action, the processor 40 may output the pinion angle through VGR adjustment according to the vehicle speed and the driving mode.

[0067] As described above, in a steer-by-wire electronic steering system for a vehicle according to an embodiment of the present disclosure, the steering angle offset and the pinion angle offset relative to the cooperative control command angle can be calculated, and then the gradually decreasing gain can be adjusted so that the cooperative control command angle and the position control angle match to switch to the steering angle position control mode to implement the autonomous driving command.

[0068] Figure 3 is a flowchart illustrating a control method of an electronic steering system for a vehicle according to an embodiment of the present disclosure.

[0069] like Figure 3 As shown, in the control method of the electronic steering system for a vehicle according to the embodiment of the present disclosure, the processor 40 first executes and drives the executable program embedded in the memory 30, and determines whether the cooperative control command angle is input from the cooperative control device through the input module 10 (S10).

[0070] As a result of the determination in S10 , if a cooperative control command angle is input from a cooperative control device such as an ADAS for autonomous driving, the processor 40 calculates a steering angle offset and a command angle offset of the vehicle ( S20 ).

[0071] Here, the steering angle offset may be calculated as a difference between the cooperative control command angle and the steering angle, and the command angle offset may be calculated as a difference between a VGR command angle and the cooperative control command angle.

[0072] After calculating the steering angle offset and the command angle offset in S20 , the processor implements steering angle position control with respect to the cooperative control command angle by sequentially and gradually reducing the steering angle offset and the command angle offset ( S30 ).

[0073] like Figure 2 As shown, the processor 40 may sequentially gradually reduce and apply the steering angle offset during feedback of the output value of the steering angle position control relative to the cooperative control command angle.

[0074] In other words, by sequentially applying gradually decreasing gains from 1 to 0, the steering angle offset can be eliminated so that the cooperative control command angle and the steering angle match each other.

[0075] Furthermore, the processor 40 may sequentially gradually reduce the steering angle offset and the command angle offset, and apply the gradually reduced offset to the output value of the steering angle position control to output the pinion angle.

[0076] In other words, by sequentially applying gradually decreasing gains from 1 to 0, the steering angle offset and the command angle offset can be controlled so that the cooperatively controlled command angle and the pinion angle match each other.

[0077] In this way, the processor 40 can control the steering wheel drive module to switch to the steering angle position control mode by sequentially eliminating the steering angle offset and the command angle offset, thereby implementing steering angle position control for the collaborative control command angle, and control the steering wheel drive module 50 (S40) by outputting the pinion angle as a result of the steering angle position control.

[0078] On the other hand, as a result of the determination in S10, if the steering angle obtained by the driver's steering action is input from the steering angle sensor 20 but the cooperative control command angle is not input, the processor 40 implements VGR adjustment according to the vehicle speed and driving mode (S50).

[0079] After performing the VGR adjustment in step S50 , the processor 40 outputs the pinion angle based on the VGR adjustment ( S60 ).

[0080] As described above, according to an embodiment of the present disclosure, in a steer-by-wire (SBW) type electronic steering system for a vehicle and a control method thereof, an autonomous driving command can be implemented by calculating a steering angle offset and a pinion angle offset relative to a collaborative control command angle, and then adjusting a gradually decreasing gain to match the collaborative control command angle with the position control angle and the pinion angle, and switching to a steering angle position control mode.

Claims

1. An electronic steering system for a vehicle, the system comprising: an input module configured to receive a steering command angle from the cooperative control unit; a steering angle sensor configured to detect a steering angle; Memory; and A processor operably connected to the input module, the steering angle sensor, and the memory, wherein the processor is configured to: calculate a steering angle offset and a command angle offset when a cooperative control command angle is input from the input module, and then implement steering angle position control relative to the cooperative control command angle by sequentially and gradually reducing the steering angle offset and the command angle offset to output a pinion angle.

2. The electronic steering system according to claim 1, wherein: The processor is configured to sequentially gradually reduce and apply the steering angle offset during feedback of an output value for steering angle position control.

3. The electronic steering system according to claim 1, wherein: The processor is configured to sequentially gradually reduce the steering angle offset and the command angle offset, and apply the gradually reduced offset to an output value of the steering angle position control to output the pinion angle.

4. The electronic steering system according to claim 1, 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 a VGR command angle and the cooperative control command angle.

5. The electronic steering system according to claim 1, wherein: The processor is configured to output a pinion angle by adjusting the VGR after the steering angle is input.

6. A method of controlling an electronic steering system for a vehicle using a processor, the method comprising: determining whether a collaborative control command angle is input from an input module; If the cooperative control command angle is input, calculating a steering angle offset and a command angle offset; and A pinion angle is output by performing steering angle position control relative to the cooperative control command angle while gradually reducing the steering angle offset and the command angle offset in sequence.

7. The method according to claim 6, wherein: The output pinion angle includes sequentially gradually reducing and applying the steering angle offset during feedback of an output value for steering angle position control.

8. The method according to claim 6, wherein: Outputting the pinion angle includes sequentially gradually reducing the steering angle offset and the command angle offset, and applying the gradually reduced offset to an output value of the steering angle position control to output the pinion angle.

9. The method according to claim 6, wherein: The steering angle offset is a difference between the cooperative control command angle and a steering angle, and the command angle offset is a difference between a VGR command angle and the cooperative control command angle.

10. The method according to claim 6, further comprising: After the steering angle is input, the pinion angle is output by adjusting the VGR.

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