Apparatus and method for controlling rear wheel steering

Abstract

The present disclosure relates to an apparatus and method for controlling rear wheel steering, the apparatus including a sensor module configured to detect steering and driving information of a rear wheel steering vehicle; and a processor configured to instantaneously vary a desired yaw rate or turning radius by further adjusting a gear ratio between the front and rear wheels in response to the column torque and vehicle speed detected by the sensor module, thereby resulting in a more dynamic lateral control than previously possible.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for controlling rear wheel steering. Background Art

[0002] Active front steering (AFS) commonly applied to vehicles ensures front wheel steering responsiveness and driving stability through a variable gear ratio steering system located between the steering wheel and the steering actuator, which is configured to receive input from the steering wheel angle, transmit the changing rotation angle to the AFS actuator, and variably adjust the steering gear ratio.

[0003] In addition, rear-wheel steering (RWS) ensures rear-wheel steering responsiveness and driving stability by determining the rear wheel angle based on inputs such as the steering wheel angle and the vehicle speed and controlling the rear wheel angle by operating the RWS actuator.

[0004] As described above, rear-wheel steering enhances rear-wheel steering responsiveness by turning the rear wheels in the opposite direction to the front wheels, reducing the turning radius during low-speed driving. In addition, rear-wheel steering ensures driving stability by turning the rear wheels in the same direction as the front wheels, reducing the yaw rate during high-speed driving. As described above, conventional rear-wheel steering simply assists front-wheel steering to control the rear wheels to prioritize steering responsiveness during low-speed driving and prioritize driving stability during high-speed driving.

[0005] Recently, in-wheel motor systems (including the concept of front-wheel and rear-wheel steering) have been developed, in which motors are embedded in the wheels of the vehicle to allow each of the four wheels to be driven independently. These in-wheel motor systems can be organically integrated into the vehicle to achieve four-wheel independent drive and four-wheel independent steering, thereby providing more flexible and variable driving performance.

[0006] Conventional vehicles equipped with four-wheel independent steering or rear-wheel steering are designed to determine the rear wheel steering angle based on the front wheel steering angle.

[0007] Determining the rear wheel steering angle in this manner impedes more dynamic vehicle control and creates limitations in utilizing the rear wheel steering capability.

[0008] In the past, steering angle velocity or angular acceleration has been used. However, there is a problem that the resolution of the steering angle sensor is low, and there is a delay in distinguishing the steering angle twice to generate the angular acceleration.

[0009] Furthermore, if only the desired yaw rate adjustment is of concern, a significant and instantaneous reversal of the gear ratio between the front and rear wheels at high speeds reduces the turning radius but affects driving stability.

[0010] Therefore, there is a need for a method of improving driver convenience and driving stability by more dynamically controlling a vehicle equipped with a rear-wheel steering device, in other words, by further adjusting the gear ratio between the front wheels and the rear wheels in response to the column torque and the vehicle speed, thereby instantaneously changing the desired yaw rate or turning radius and achieving more dynamic lateral control than was previously possible.

[0011] The related technology of the present disclosure is disclosed in Korean Patent Registration No. 10-2274120 (registered on July 1, 2021, entitled "Device and method for controlling rear wheel steering"). Summary of the invention

[0012] Various embodiments developed to address the above-mentioned problems relate to an apparatus and method for controlling rear-wheel steering, which improves driver convenience and driving stability by further adjusting the gear ratio between the front wheels and the rear wheels in response to the column torque and the vehicle speed, instantaneously changing the desired yaw rate or turning radius, and achieving more dynamic lateral control than was previously possible.

[0013] According to one aspect of the present disclosure, a device for controlling rear-wheel steering includes: a sensor module configured to detect steering and driving information of a rear-wheel steering vehicle; and a processor configured to respond to column torque and vehicle speed detected by the sensor module, and to instantaneously change a desired yaw rate or turning radius by further adjusting the gear ratio between the front wheels and the rear wheels, thereby resulting in more dynamic lateral control than was previously possible.

[0014] In one embodiment, the processor may control the vehicle in a reverse direction mode at a low speed section below a prescribed speed.

[0015] In one embodiment, the processor may additionally control the rear wheels only when needed to avoid obstacles or make sharp turns in high speed sections above or equal to a specified speed, while mainly steering in the same directional mode.

[0016] In one embodiment, the processor may change the front and rear wheel angles based on changes in column torque, where the column torque is applied to a differentiator and the result is passed through a low pass filter (LPF) to remove noise.

[0017] In one embodiment, the processor may determine a rear wheel angle proportional to the front wheel angle based on a desired yaw rate, wherein a closed-loop controller is applied to track a stable yaw rate based on the desired yaw rate that satisfies conditions required to achieve a stable yaw rate, and to control the front and rear wheels in the same or opposite directions depending on the vehicle speed.

[0018] In one embodiment, the processor may apply a predetermined ratio table to set the ratios for adjusting the front wheel angles and the rear wheel angles based on changes in column torque.

[0019] In one embodiment, the processor may adjust the front and rear wheel angles based on a ratio table, wherein the angles dynamically increase as the ratio increases in response to sudden changes in driver steering or large increases in column torque.

[0020] In one embodiment, when wheel angles are additionally controlled based on changes in column torque, the processor may also compensate only rear wheel angles in opposite direction mode but compensate front and rear wheel angles in same direction mode according to a ratio table.

[0021] In one embodiment, the processor can drive an ON / OFF control module, which performs ON / OFF control based on signals received from the front wheels and the rear wheels and a ratio table, wherein the ON / OFF control module switches between ON and OFF states, and further compensates only the rear wheel angle in an opposite direction mode, but compensates the front wheel angle and the rear wheel angle in the same direction mode when the wheel angle is additionally controlled based on changes in vehicle speed and column torque.

[0022] According to another aspect of the present disclosure, a method for controlling rear-wheel steering includes: detecting steering and driving information of a rear-wheel steering vehicle through a sensor module; and in response to the column torque and vehicle speed detected by the sensor module, further adjusting the gear ratio between the front wheels and the rear wheels through a processor, instantaneously changing the desired yaw rate or turning radius, thereby resulting in more dynamic lateral control than was previously possible.

[0023] According to the present disclosure, driver convenience and driving stability can be improved by further adjusting the gear ratio between the front wheels and the rear wheels in response to the column torque and the vehicle speed, thereby resulting in instantaneous changes in the desired yaw rate or turning radius and achieving more dynamic lateral control than was previously possible.

[0024] According to the present disclosure, more dynamic vehicle control can be achieved because in the low-speed section, the vehicle is controlled without responding to the steering angle acceleration while stably minimizing the turning radius; and in the high-speed section, the rear wheels are additionally controlled only when needed to avoid obstacles or make sharp turns, while steering mainly in the same direction mode to reduce the slip angle and maintain a minimum yaw rate.

[0025] According to the present disclosure, additional compensation control is performed in the opposite direction mode when the rear wheels rotate in the opposite direction to the front wheels, and additional compensation control is performed in the same direction mode when the rear wheels rotate in the same direction as the front wheels, which can further improve the driving stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram showing a schematic configuration of a four-wheel independent steering apparatus including rear-wheel steering according to an embodiment of the present disclosure.

[0027] Figure 2 It is shown Figure 1 A schematic diagram of the configuration of the lateral control is described in more detail in FIG. DETAILED DESCRIPTION

[0028] 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 a field programmable gate array (FPGA), other electronic devices, or a combination thereof. At least some of the functions or processes described in the exemplary embodiments may be implemented by software, and the software may be recorded on a recording medium. The components, functions, and processes described in the exemplary embodiments may be implemented by a combination of hardware and software.

[0029] The method according to the exemplary embodiment may be embodied as a computer-executable program and may be implemented as various recording media such as a magnetic storage medium, an optical reading medium, and a digital storage medium.

[0030] The various techniques described herein may be implemented as digital electronic circuits, or as computer hardware, firmware, software, or a combination thereof. These techniques may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, such as a machine-readable storage device (e.g., a computer-readable medium) or in a propagated signal, for processing or controlling the operation of a data processing device by a data processing device, such as a programmable processor, a computer, or multiple computers. Computer programs may be written in any form of programming language (including compiled or interpreted languages) and may be deployed in any form (including stand-alone programs or modules, components, subroutines, or other units suitable for use in a computing environment). Computer programs may be deployed to execute on a single computer, or on multiple computers at a single site or distributed across multiple sites and interconnected by a communication network.

[0031] Processors suitable for executing computer programs include, for example, general-purpose microprocessors and special-purpose microprocessors, and any one or more processors of any type of digital computer. Typically, the processor receives instructions and data from a read-only memory or a random access memory or both. The 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 will also include or be connected to receive data from one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks), transmit data to one or more mass storage devices, or perform both on one or more mass storage devices to store data. Examples of information carriers suitable for embodying computer program instructions and data include semiconductor memory devices, such as magnetic media, such as hard disks, floppy disks, and magnetic tapes; optical media, such as compact disk read only memory (CD-ROM), digital video disk (DVD), etc.; and magneto-optical media, such as floppy disks, read only memory (ROM), random access memory (RAM), flash memory, erasable programmable ROM (EPROM) and electrically erasable programmable ROM (EEPROM), and any other known computer-readable medium. The processor and memory may be supplemented by or integrated into special purpose logic circuitry.

[0032] 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, operate, process, and create data in response to the execution of the software. For simplicity, the processor device is described using the singular; however, those skilled in the art will appreciate that the processor device may include multiple processing elements and / or multiple types of processing elements. For example, the processor device may include multiple processors or a processor and a controller. In addition, different processing configurations are possible, such as parallel processors.

[0033] Additionally, 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.

[0034] This specification includes some details of specific implementations, but it should be understood that these details do not limit any invention or what may be claimed in the specification, but rather describe features of specific exemplary embodiments. Features described in the specification in the context of separate exemplary embodiments may be implemented as a combination in a single exemplary embodiment. Conversely, various features described in the specification in the context of a single exemplary embodiment may be implemented in multiple exemplary embodiments individually or in appropriate sub-combinations. In addition, these features may operate in a specific combination and may initially be described as claimed in the combination, but in some cases, one or more features may be excluded from the claimed combination, and the claimed combination may become a sub-combination or a modification of the sub-combination.

[0035] Likewise, 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. In addition, it should not be understood that the various device components in the above exemplary embodiments are required to be separated in all exemplary embodiments, and it should be understood that the above program components and devices can be incorporated into a single software product, or can be packaged in multiple software products.

[0036] It should be understood that the exemplary embodiments disclosed herein are merely illustrative and are not intended to limit the scope of the present invention. For those of ordinary skill in the art, it is obvious that various modifications may be made to the exemplary embodiments without departing from the spirit and scope of the technical solutions claimed in the present disclosure and their equivalents.

[0037] Hereinafter, with reference to the accompanying drawings, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily implement the present disclosure. However, the present disclosure can 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, when the detailed description of known functions and configurations incorporated herein may make the subject matter of the present disclosure rather unclear, these descriptions will be omitted. In the accompanying drawings, parts irrelevant to the description of the present disclosure are omitted, and similar parts are represented by similar reference numerals.

[0039] In the present disclosure, components that are distinguished from each other are intended to clearly illustrate each feature. However, this does not necessarily mean that these components are separate. That is, multiple components can be integrated into one hardware or software unit, or a single component can be distributed to multiple hardware or software units. Therefore, unless otherwise stated, such integrated or distributed embodiments are also included in the scope of the present disclosure.

[0040] In the present disclosure, the components described in the various embodiments are not necessarily necessary components, and some may be optional components. Therefore, embodiments consisting of a subset of the components described in one embodiment are also included in the scope of the present disclosure. In addition, embodiments that include other components in addition to the components described in the various embodiments are also included in the scope of the present disclosure.

[0041] 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 further including other components rather than excluding other components, unless explicitly described to the contrary.

[0042] In the present disclosure, the terms first, second, etc. are used only for the purpose of distinguishing one component from another component, and do not limit the order or importance of the components, etc., unless otherwise explicitly stated. 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.

[0043] Figure 1 is a schematic diagram showing a schematic configuration of a four-wheel independent steering apparatus including rear-wheel steering according to an embodiment of the present disclosure.

[0044] like Figure 1 As shown, the four-wheel independent steering device according to the embodiment of the present disclosure includes a sensor module 110, a storage module 120, a processor 130, a front-wheel drive module 140 and a rear-wheel drive module 150.

[0045] The sensor module 110 may include a current sensor (or a current detection sensor), a steering angle sensor (or a steering angle detection sensor), and a yaw rate sensor.

[0046] The sensor module 110 may include wheel speed sensors each included in the front wheels and the rear wheels, and an acceleration sensor that detects vehicle acceleration.

[0047] The sensor module 110 may sense information related to vehicle operation, such as braking.

[0048] The processor 130 may measure the steering angle via a steering angle sensor.

[0049] The processor 130 may calculate the driver's desired yaw rate using the steering angle during the steering operation, the driving direction, and the vehicle speed during the accelerator pedal depression.

[0050] The storage module 120 may store an algorithm for the processor 130 to control the rear wheel driving force, and store information (or data) detected by the sensor module 110 .

[0051] In this case, the memory module 120 and the processor 130 may be implemented as separate chips, or may be implemented as a single chip configured to include the memory module 120 inside the processor 130 .

[0052] The storage module 120 may also be implemented as, but not limited to, at least one of the following: a non-volatile storage device such as a cache, a read-only memory (ROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), and a flash memory, or a volatile storage device such as a random access memory (RAM), or a storage medium such as a hard disk drive (HDD) or a CD-ROM.

[0053] Furthermore, the processor 130 may be implemented as an electronic control unit (ECU) that controls the vehicle while traveling.

[0054] The front wheel drive module 140 may be connected to the front wheels (FW1, FW2). Under the control of the processor 130, the front wheel drive module 140 may drive the actuators of the front wheels (FW1, FW2) (e.g., actuators that adjust the rotation direction, speed, and steering angle of the front wheels through motors or hydraulics).

[0055] The front wheel drive module 140 may be included in the processor 130 .

[0056] The rear wheel drive module 150 may be connected to the rear wheels (RW1, RW2). Under the control of the processor 130, the rear wheel drive module 150 may drive the actuators of the rear wheels (RW1, RW2) (e.g., actuators that adjust the rotation direction, speed, and steering angle of the rear wheels through motors or hydraulics).

[0057] The rear wheel drive module 150 may be included in the processor 130 .

[0058] In addition, the processor 130 can control both the front wheel drive module 140 and the rear wheel drive module 150 to make the steering angles of the front wheels and the rear wheels the same (ie, same direction control) or different (ie, opposite direction control).

[0059] The processor 130 may instantaneously change the desired yaw rate or turning radius by further adjusting the gear ratio between the front and rear wheels in response to column torque and vehicle speed.

[0060] This may enable more dynamic lateral control than was previously possible.

[0061] In the low speed section, the processor 130 may control the vehicle while stably minimizing the turning radius without responding to the steering angle acceleration.

[0062] In high speed sections, the processor 130 may also control the rear wheels only when needed to avoid obstacles or make sharp turns, while steering primarily in the same directional pattern to reduce the slip angle and maintain a minimum yaw rate.

[0063] This may enable more dynamic lateral control than was previously possible.

[0064] When the rear wheels rotate in the opposite direction to the front wheels, the processor 130 may perform additional compensatory control in the opposite direction mode, and when the rear wheels rotate in the same direction as the front wheels, the processor 130 may perform additional compensatory control in the same direction mode.

[0065] This may enable even more improved driving stability than was previously possible.

[0066] Will refer to the following Figure 2 The rear wheel steering controlled by the processor 130 is described.

[0067] Figure 2 is shown for a more specific description Figure 1 Schematic diagram of a configuration for lateral control in FIG. According to the present disclosure, rear wheel steering control may enable more dynamic lateral control than was previously possible.

[0068] Reference Figure 2 , the column torque may be applied to a differentiator 131 for differentiation, and the result may pass through a first low pass filter (LPF) 132 to eliminate noise.

[0069] Accordingly, the front and rear wheel angles (ie, tire angles) may be adjusted differentially based on changes in column torque.

[0070] Essentially, rear-wheel steering determines the rear wheel angle in proportion to the front wheel angle based on the desired yaw rate.

[0071] In an embodiment of the present disclosure, a closed-loop controller may be applied to the processor 130 to track a stable yaw rate based on a desired yaw rate that satisfies the conditions required to achieve a stable yaw rate, and control the front and rear wheels in the same or opposite directions according to the vehicle speed.

[0072] In an embodiment of the present disclosure, based on column torque changes, front and rear wheel angles may be applied outside of the driver's steering range to instantaneously respond to the driver's steering (or steering intent), resulting in more dynamic lateral control than was previously possible.

[0073] Note that embodiments of the present disclosure may be applied to vehicles such as shift-by-wire (SBW) or four-wheel steering (4WS) vehicles. These vehicles are configured to utilize a structure in which a rack bar is movably controlled by a motor (not shown) of an electric power steering without the assistance of a column equipped with a steering force actuator, relying only on wires.

[0074] In an embodiment of the present disclosure, a ratio for adjusting the wheel angle based on a change in column torque may be set by applying a predetermined ratio table 130 established through testing.

[0075] In this case, when the column torque changes the least, the ratio value is set to 1. Therefore, when the angle tracking the stable yaw rate (or steady-state yaw rate) is controlled, the front wheel angle and the rear wheel angle can be dynamically increased, and the ratio will increase in response to a sudden change in the driver's steering or a large increase in column torque.

[0076] Under the conditions required to achieve a stable yaw rate, when the vehicle speed is higher than or equal to a prescribed speed (e.g., high speed), both the front wheels and the rear wheels are controlled in the same direction. However, when the vehicle speed is lower than the prescribed speed (e.g., low speed), the front wheels and the rear wheels are controlled in opposite directions. Importantly, when the wheel angles are additionally controlled based on the change in column torque, only the rear wheel angle is further compensated in the opposite direction mode (i.e., low speed), while both the front wheel and rear wheel angles are compensated in the same direction mode (i.e., high speed).

[0077] Therefore, the on / off control module 133 performs on / off control based on the signals received from the front and rear wheels and the ratio table 130 .

[0078] For example, the on / off control module 133 switches between on (ON) and off (OFF) states, and when the wheel angles are additionally controlled based on changes in vehicle speed and column torque, only the rear wheel angles are compensated in the opposite direction mode (i.e., at low speeds), but both the front wheel angles and the rear wheel angles are compensated in the same direction mode (i.e., at high speeds).

[0079] If the algorithm according to the embodiment of the present disclosure is not applied, it is shown that even at high speeds, the rear wheel angle is controlled in the opposite direction rather than the same direction to track the desired yaw rate, or if only the rear wheels are further compensated in the same direction, it is difficult to perform normal sharp turns. In addition, considering the angle that the wheel may mechanically turn, the maximum ratio is variably adjusted in real time to be less than the maximum @ (i.e., the maximum limit angle of the steering limit).

[0080] For example, under normal driving conditions, the front and rear wheel angles can turn about 30 to 40 degrees. Therefore, the maximum @ (i.e., the maximum limit angle of the steering limit) is adjusted to prevent the wheel angle from turning beyond the limit. If the driver turns with the wheel angle at 20 degrees and then momentarily makes an additional turn, the maximum @ is limited to a specific limit value (e.g., 2).

[0081] The final ratio value is determined by referencing the ratio table 130. For example, if the ratio value is set to 1.2, the wheel angle may be adjusted to 20% more turns than the previous setting.

[0082] The embodiments of the present disclosure describe Figure 2 The ratio table 130, the differentiator 131, the first LPF 132 and the on / off control module 133 in FIG. Since the remaining components (134 to 138) mainly track the stable yaw rate reference, only a brief description is provided.

[0083] As shown in the following equation 1, a stable yaw rate reference (or steady-state yaw rate reference) which is not explicitly described in detail in the embodiment of the present disclosure is determined.

[0084] [Formula 1]

[0085]

[0086] Where K = K US It represents the understeer gradient value, V is the vehicle speed, L is the vehicle wheelbase length, g is the acceleration of gravity, δf is the front wheel steering angle, and δr is the rear wheel steering angle.

[0087] In the reference model 137, the vehicle speed (V) and the lateral acceleration (ay) sensed in the vehicle are fed back to the third LPF 136, which calculates a stable yaw rate reference. Due to severe noise in the yaw rate sensed in the vehicle, the sensed yaw rate is fed back to the second LPF 135 to compensate for the stable yaw rate reference, and the result is then applied to the controller 138.

[0088] Therefore, the controller 138 participates in closed loop control. In other words, the controller 138 adjusts the difference between the desired yaw rate and the feedback yaw rate to zero by minimizing the error to zero. Figure 2 In the figure, B is the body slip angle.

[0089] Note that the sensed yaw rate of the dynamic four-wheel steering (4WS) calculated and fed back from the control model 134 passes through the second LPF 135 (or Kalman filter) to eliminate noise. US ) or variable gradient value (K VS) to adapt to the driver's steering preferences, such as steering angle velocity or angular acceleration. This allows oversteering, neutral steering and understeering behavior to be executed accordingly.

[0090] According to the present disclosure, as described above, by further adjusting the gear ratio between the front wheels and the rear wheels in response to the column torque and the vehicle speed, thereby instantaneously changing the desired yaw rate or turning radius and achieving more dynamic lateral control than was previously possible, driver convenience and driving stability can be improved.

[0091] According to the present invention, since in the low-speed section, the vehicle is controlled while stably minimizing the turning radius without accelerating in response to the steering angle, and in the high-speed section, the rear wheels are additionally controlled only when necessary to avoid an obstacle or make a sharp turn while steering mainly in the same direction mode to reduce the slip angle and maintain a minimum yaw rate, more dynamic vehicle control can be achieved.

[0092] Furthermore, according to the present disclosure, additional compensation control is performed in the opposite direction mode when the rear wheels rotate in the opposite direction to the front wheels, and additional compensation control is performed in the same direction mode when the rear wheels rotate in the same direction as the front wheels, which can further improve driving stability.

Claims

1. A device for controlling rear wheel steering, comprising: a sensor module configured to detect steering and driving information of a rear-wheel steering vehicle; and A processor is configured to instantaneously change the desired yaw rate or turning radius by further adjusting the gear ratio between the front wheels and the rear wheels in response to the column torque and the vehicle speed detected by the sensor module.

2. The device according to claim 1, wherein The processor controls the vehicle in a reverse direction mode in a low speed section below a prescribed speed.

3. The device according to claim 1, wherein The processor additionally controls the rear wheels only when needed to avoid obstacles or make sharp turns in a high-speed section above or equal to a prescribed speed, while mainly steering in the same directional mode.

4. The device according to claim 1, wherein The processor changes the front wheel angle and the rear wheel angle based on the change in column torque, in, The column torque is applied to a differentiator and the result is passed through a low pass filter (LPF) to remove noise.

5. The device according to claim 1, wherein the processor determining a rear wheel angle proportional to the front wheel angle based on the desired yaw rate, in, A closed-loop controller is used to track a stable yaw rate based on a desired yaw rate that satisfies a condition required to achieve a stable yaw rate, and to control the front and rear wheels in the same or opposite directions according to the vehicle speed.

6. The device according to claim 1, wherein The processor sets a ratio for adjusting the front wheel angle and the rear wheel angle based on a change in column torque using a predetermined ratio table.

7. The device according to claim 6, wherein The processor adjusts the front wheel angle and the rear wheel angle based on the ratio table, in, The front and rear wheel angles increase dynamically as the ratio increases in response to sudden changes in driver steering or large increases in column torque.

8. The device according to claim 1, wherein When the wheel angles are additionally controlled based on changes in column torque, the processor compensates only the rear wheel angles in an opposite direction mode but compensates both the front wheel angles and the rear wheel angles in a same direction mode according to the ratio table.

9. The device according to claim 8, wherein The processor drives an on / off control module, which performs on / off control based on signals received from the front wheels and the rear wheels and the ratio table, in, The on / off control module switches between on and off states when the wheel angles are additionally controlled based on changes in vehicle speed and column torque, further compensating only the rear wheel angles in the opposite direction mode but compensating the front wheel angles and the rear wheel angles in the same direction mode.

10. A method for controlling rear wheel steering, the method comprising: Detecting steering and driving information of rear-wheel steering vehicles through sensor modules; and The gear ratio between the front and rear wheels is further adjusted by the processor in response to the column torque and vehicle speed detected by the sensor module, instantaneously changing the desired yaw rate or turning radius, thereby resulting in more dynamic lateral control than was previously possible.

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