Steer-by-wire device of a vehicle

Abstract

According to the present invention, in a steer-by-wire apparatus for a vehicle, there is provided a rack shaft on which a rack gear is installed and which adjusts the steering angle of a vehicle wheel by the linear motion of the rack gear; a pinion gear meshed with the rack gear and linearly moving the rack gear by a rotational motion; a first sun gear and a second sun gear installed to face each other, at least one planetary gear meshed with the first sun gear and the second sun gear and revolving about a revolution axis connecting the center point of the first sun gear and the center point of the second sun gear corresponding to the rotational motion of at least one of the first sun gear and the second sun gear, and a differential gear module including a case coupled to the planetary gear and rotating about the revolution axis and coupled to the pinion gear; a first actuator and a second actuator for rotating the first sun gear and the second sun gear, respectively; at least one controller for controlling the first actuator and the second actuator in response to steering input information; and a steering sensor for sensing at least part of the momentum of the rack gear and the pinion gear; A steer-by-wire apparatus is disclosed.

Description

[Technical Field]

[0001] The present invention relates to a steer-by-wire system for a vehicle, and more particularly to a steer-by-wire system for a vehicle that can provide redundancy for dealing with not only an electrical failure but also a mechanical failure of an actuator for driving a wheel steering mechanism of the steer-by-wire system for a vehicle. [Background technology]

[0002] A steer-by-wire system is a steering system that completely eliminates the mechanical connection between the vehicle's steering wheel and the wheel steering mechanism, and transmits and controls the driver's steering wheel operation to the wheel steering mechanism using electrical signals.

[0003] In a steer-by-wire system, the mechanical connection between the vehicle's steering wheel and the wheel steering mechanism is completely eliminated and the system is controlled by electrical signals, so the driver's operation of the steering wheel can be directly reflected in the wheel steering mechanism, unnecessary vibrations can be blocked, the steering gear ratio can be freely changed, and unintended steering inputs by the driver can basically be blocked during autonomous driving.

[0004] The structure of a conventional steer-by-wire system 1000 will be described below with reference to FIG.

[0005] 1, a conventional steer-by-wire system 1000 may include a steering input mechanism 1100 that receives steering input information from a user on a steering wheel (not shown). The steering input mechanism 1100 may include a steering wheel sensor that detects the amount of movement of the steering wheel.

[0006] The conventional steer-by-wire system 1000 may include a wheel steering mechanism 1200 that steers the wheels of the vehicle. Here, the wheel steering mechanism 1200 may include a rack shaft 1210 that adjusts the steering angle of the wheels of the vehicle depending on the position, and a steering sensor 1270 that senses the position of the rack shaft 1210. The wheel steering mechanism 1200 may also include a controller (not shown) that controls the wheel steering mechanism 1200 by referring to steering input information from the steering input mechanism 1100.

[0007] At this time, steering input information of the steering input mechanism 110 can be transmitted to the controller of the wheel steering mechanism 1200 using CAN (Controller Area Network) communication.

[0008] However, since the steer-by-wire system has no mechanical connection between the steering wheel of the vehicle and the steering mechanism of the wheels, if an electrical failure occurs in the system itself, there is a major safety issue in that steering control cannot be performed at all even if the driver operates the steering wheel.

[0009] To prevent this, existing technology uses electronic control duplication to maintain steering control using the second electronic control controller even if the first electronic control controller fails.

[0010] However, in the case of such a steer-by-wire system, if a mechanical failure occurs in the actuator of the wheel steering mechanism itself, steering control becomes impossible, which may lead to a serious accident.

[0011] Therefore, there is a need to develop a steer-by-wire system that can provide redundancy for steering control even if a mechanical failure occurs in the actuator of the wheel steering mechanism itself. Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to solve all of the above-mentioned problems.

[0013] Another object of the present invention is to provide a steer-by-wire system that is capable of steering control even if a failure occurs in the actuator of the wheel steering mechanism.

[0014] Another object of the present invention is to provide redundancy for not only electrical failure but also mechanical failure of the actuator of the wheel steering mechanism.

[0015] In addition, the sun gear is rotated without being driven by the rotation of the planetary gear of the present invention. Steer-by-wire system Another object of the present invention is to provide redundancy.

[0016] Another object of the present invention is to provide redundancy in the event of an actuator failure in the steer-by-wire system while minimizing spatial constraints. [Means for solving the problem]

[0017] According to one embodiment of the present invention, there is provided a steer-by-wire device for a vehicle, including: a rack shaft having a rack gear mounted thereon and adjusting a steering angle of a vehicle wheel by linear motion of the rack gear; a pinion gear meshed with the rack gear and rotating to cause linear motion of the rack gear; a first sun gear and a second sun gear disposed opposite each other; at least one planetary gear meshed with the first sun gear and the second sun gear and revolving around an axis of revolution connecting a center point of the first sun gear and a center point of the second sun gear in response to rotational motion of at least one sun gear among the first sun gear and the second sun gear; and a differential gear module including a case coupled to the planetary gear and rotating around the axis of revolution and coupled to the pinion gear; a first actuator and a second actuator rotating the first sun gear and the second sun gear, respectively; at least one controller controlling the first actuator and the second actuator in response to steering input information; and a steering sensor detecting at least a portion of the momentum of the rack gear and the pinion gear.

[0018] In one example, the controller determines a rack load condition when steering the vehicle by referring to vehicle driving state information, and if the rack load condition exceeds a predetermined first load value, controls the first actuator and the second actuator to adjust the steering angle of the vehicle wheel, and if the rack load condition is equal to or less than a predetermined second load value (the predetermined second load value is smaller than the predetermined first load value), controls one specific actuator from the first actuator and the second actuator to adjust the steering angle of the vehicle wheel.

[0019] In one example, when the rack load condition is equal to or less than the second predetermined load value and the steering angle of the vehicle wheel is adjusted by controlling the specific actuator, if the momentum of at least a part of the rack gear and the pinion gear detected by the steering sensor is smaller than a target momentum corresponding to the steering input information by an allowable threshold or more, the controller determines that the specific actuator has failed and controls another actuator to adjust the steering angle of the vehicle wheel.

[0020] In one example, when a specific controller among the controllers controls the first actuator and the second actuator, if another controller other than the specific controller (which can control the first actuator and the second actuator) cannot receive operating status information from the specific controller for a certain period of time, it is determined that the specific controller has failed and controls the first actuator and the second actuator instead of the specific controller so that the steering angle of the vehicle wheels is adjusted.

[0021] In one example, the first actuator and the second actuator each include a respective first locking unit and a respective second locking unit that locks and unlocks the rotation of the first sun gear and the second sun gear.

[0022] In one example, the first actuator includes a first motor that generates power, a first reducer that converts the power generated from the first motor to correspond to the first power value, and a first sun gear shaft that connects the first reducer to the first sun gear, and the second actuator includes a second motor that generates power, a second reducer that converts the power generated from the second motor to correspond to the second power value, and a second sun gear shaft that connects the second reducer to the second sun gear.

[0023] In one example, the first motor includes 1_1 windings through 1_n windings (where n is an integer equal to or greater than 2) that generate power for the first motor, the second motor includes 2_1 windings through 2_n windings that generate power for the second motor, and the controllers include 1st controller through nth controller, and when the 1_1 winding and the 2_1 winding are defined as a first winding pair, the 1st winding pair through the nth winding pair are connected to and controlled by the 1st controller through the nth controller, respectively.

[0024] In one example, the first motor includes a first winding that generates power for the first motor, and the second motor includes a second winding that generates power for the second motor. The controllers include a specific controller and another controller. When the specific controller controls the first winding and the second winding in a state where the first winding and the second winding are connected to the specific controller and the other controller, respectively, and another controller other than the specific controller (the other controller can control the first winding and the second winding) does not receive operation status information from the specific controller for a certain period of time, the specific controller is determined to have failed, and power for the first motor and the second motor is generated by the first winding and the second winding, respectively. [Effects of the Invention]

[0025] The present invention has the following advantages.

[0026] The present invention enables the steer-by-wire system to control steering even if a failure occurs in the actuator of the steering mechanism of the wheels, thereby improving the running stability of the vehicle.

[0027] The present invention allows for the rotation of a sun gear that is not driven by the rotation of the planetary gears of a steer-by-wire system.

[0028] The present invention can easily realize redundancy in the event of a failure of an actuator of a steer-by-wire system without spatial constraints. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 shows a simplified diagram of a conventional steer-by-wire system. [Figure 2] FIG. 2 is a simplified diagram of a part of a steer-by-wire system according to an embodiment of the present invention. [Figure 3] FIG. 3 is a simplified cross-sectional view of a portion of a steer-by-wire system according to an embodiment of the present invention. [Figure 4] FIG. 4 is a simplified diagram illustrating a configuration in which a first lock unit and a second lock unit are installed in a steer-by-wire system according to an embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart illustrating a process in which a controller controls the first and second actuators according to a rack load in a steer-by-wire system according to an embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating a process in which a controller controls the first and second actuators depending on whether a specific controller has a failure or not in a steer-by-wire system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following detailed description of the present invention refers to the accompanying drawings, which show, by way of example, specific embodiments in which the invention may be practiced. These embodiments are described in detail to enable those skilled in the art to practice the invention. It should be understood that various embodiments of the present invention, although different from one another, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention. It should also be understood that the location or arrangement of individual components within each disclosed embodiment may be modified without departing from the spirit and scope of the invention. Therefore, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention is limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if appropriate. Like reference numerals in the drawings refer to the same or similar components throughout the various aspects.

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention.

[0032] First, the steer-by-wire system for a vehicle according to the present invention will be described with reference to FIGS.

[0033] FIG. 2 is a simplified diagram of a part of a steer-by-wire system according to an embodiment of the present invention. FIG. 3 is a simplified cross-sectional view of a portion of a steer-by-wire system according to an embodiment of the present invention.

[0034] 2 and 3, the steer-by-wire device for a vehicle according to the present invention may include a rack shaft on which a rack gear 2220 is installed and which adjusts the steering angle of the vehicle wheels through the linear motion of the rack gear 2220. Here, the rack shaft may also adjust the steering angle of the vehicle wheels through its own linear motion.

[0035] The rack gear 2220 may be meshed with a pinion gear 2230 that causes the rack gear 2220 to move linearly through rotational motion.

[0036] Here, the pinion gear 2230 has a cylindrical shape and may be engaged at a certain point on its circumference with the rack gear 2220. At this time, the pinion gear 2230 can rotate in both clockwise and counterclockwise directions from its original position, and the direction of movement of the rack gear 2220 may be reversed depending on the direction of rotation of the pinion gear 2230.

[0037] A steer-by-wire system for a vehicle according to the present invention may also include a differential gear module 2240.

[0038] As an example, the differential gear module 2240 may include a first sun gear 2241 and a second sun gear 2242 disposed opposite each other.

[0039] A planetary gear 2243 may be disposed between the first sun gear 2241 and the second sun gear 2242 and meshed with the first sun gear 2241 and the second sun gear 2242 simultaneously.

[0040] At this time, the planetary gear 2243 can revolve around the revolution axis connecting the center point of the first sun gear 2241 and the center point of the second sun gear 2242 in response to the rotational movement of at least one sun gear among the first sun gear 2241 and the second sun gear 2242. The planetary gear 2243 can also rotate on its axis due to the difference in driving force between the first sun gear 2241 and the second sun gear 2242. That is, when one of the first sun gear 2241 and the second sun gear 2242 is not driven, the planetary gear 2243 can be rotated on its axis due to the driving force of the driven sun gear, and the rotation of the planetary gear 2243 can also rotate the non-driven sun gear. The planetary gear 2243 can also revolve around the revolution axis due to the driving force of the driven sun gear. The number of planetary gears 2243 is not limited, and multiple planetary gears 2243 can be present as long as they are simultaneously engaged with the first sun gear 2241 and the second sun gear 2242.

[0041] The differential gear module 2240 may include a case 2244 coupled to the pinion gear 2230 and rotates around an axis of revolution about which the planetary gear 2243 revolves.

[0042] In this case, the case 2244 may be cylindrical and may enclose the first sun gear 2241, the second sun gear 2242, and the planetary gear 2243, but is not limited to this form and may rotate in its original position around the same axis as the axis of revolution around which the planetary gear 2243 revolves.

[0043] Meanwhile, although an example of the differential gear module 2240 has been described above, the present invention is not limited thereto, and the differential gear module 2240 can be configured in various ways so that the planetary gears revolve by the driving force of the sun gear.

[0044] Furthermore, the steer-by-wire system for a vehicle according to the present invention may include a first actuator 2250 and a second actuator 2260 that rotate the first sun gear 2241 and the second sun gear 2242, respectively.

[0045] Here, the first actuator 2250 and the second actuator 2260 are configured to receive power through different routes, so that even if the power supply to one of the actuators is stopped, power can still be supplied to the other actuator.

[0046] Meanwhile, the first actuator 2250 and the second actuator 2260 may be installed parallel to the linear motion direction of the rack gear 2220 to minimize installation space, and the rotational power of the first actuator 2250 and the second actuator 2260 may be converted and transmitted through their respective bevel gears to the shaft directions of the first sun gear 2241 and the second sun gear 2242. As a result, the present invention does not require separate configurations for transmitting the driving force of the first actuator 2250 and the second actuator 2260 for driving the rack-pinion for controlling the steering of the vehicle wheels, but instead performs rack-pinion driving by the first actuator 2250 and the second actuator 2260 through one differential gear module 2240, thereby easily implementing redundancy in the event of an actuator failure without spatial constraints. In this case, each bevel gear can act as a reducer for adjusting the rotational power transmitted from the first actuator 2250 to the first sun gear 2241 and the rotational power transmitted from the second actuator 2260 to the second sun gear 2242. However, in the present invention, the reducer for adjusting the rotational power is not limited to a bevel gear, and reducers of various shapes can be used depending on the installation direction of the first actuator 2250 and the second actuator 2260.

[0047] In addition, the first sun gear shaft, which transmits the driving force from the first actuator 2250 to the first sun gear, may be coupled to the sun gear through a hollow formed in the pinion gear 2230 .

[0048] In addition, the steer-by-wire system for a vehicle according to the present invention may include at least one controller that controls the first actuator 2250 and the second actuator 2260 in response to steering input information for automatically steering the vehicle according to steering wheel operation by the driver or vehicle driving information. At this time, the number of controllers and the control relationship may be implemented in various forms, which will be described later. in explain.

[0049] The steer-by-wire system for a vehicle according to the present invention may include a steering sensor that detects at least a portion of the momentum of the rack gear 2220 and the pinion gear 2230. In this case, the steering sensor may detect the linear momentum of the rack gear 2220 and the rotational momentum of the pinion gear 2230.

[0050] In the steer-by-wire system for a vehicle according to the present invention configured as described above, the first sun gear 2241 and the second sun gear 2242 rotate due to the driving force of the first actuator 2250 and the second actuator 2260, thereby rotating the planetary gear 2243. The case 2244 rotates in conjunction with the rotation of the planetary gear 2243, and the rotational movement of the pinion gear 2230 in conjunction with this causes the rack gear 1220 to move linearly, thereby controlling the steering angle of the vehicle wheels.

[0051] Next, an embodiment in which a lock unit is used in a steer-by-wire system according to the present invention will be described with reference to FIG.

[0052] According to the above-described embodiment of the present invention, the undriven sun gear can be rotated by the rotation of the planetary gears 2243. However, when the rotation speed of the driven sun gear is high, for example, when a reducer with a low reduction ratio is used, the driving force of the normally driven sun gear may be dispersed to the undriven actuator through the undriven sun gear. To prevent this, the first actuator 2250 and the second actuator 2260 may each include a first locking unit 2310 and a second locking unit 2320 that lock or unlock the rotation of the first sun gear 2241 and the second sun gear 2242, respectively. In this case, the first locking unit 2310 and the second locking unit 2320 may be installed at any position on the driving force transmission path from each sun gear to each actuator, and may be embodied in various structures that can lock the driving force transmission, i.e., the rotational movement on the driving force transmission path. For example, it can be configured in various forms, such as providing a frictional force directly to the driving force transmission shaft to prevent the rotation of the driving force transmission shaft, or meshing with any gear device on the driving force transmission path to prevent the gear from rotating.

[0053] FIG. 4 is a simplified diagram showing a configuration in which a first locking unit 2310 and a second locking unit 2320 are installed in a steer-by-wire system according to an embodiment of the present invention.

[0054] Referring to FIG. 4, in the present invention, each of the first actuator 2250 and the second actuator 2260 may include a first lock unit 2310 and a second lock unit 2320, respectively.

[0055] In this case, the first locking unit 2310 and the second locking unit 2320 may each be configured with a solenoid valve, and each solenoid valve may be installed in the reducer of the first actuator 2250 and the second actuator 2260. However, the present invention is not limited to this, and various devices that block rotational force on the driving force transmission path other than the solenoid valve may be used in the locking unit, and may be installed at various positions on the driving force transmission path other than the reducer.

[0056] The solenoid valve is locked to prevent the reduction gear from rotating, and while maintaining the reduction gear in a cut-off state of driving force transmission, the solenoid valve is driven in response to an actuator drive signal to enter an unlocked state, thereby enabling the actuator drive signal to release the cut-off of driving force transmission in the reduction gear.

[0057] As a result, if a fault occurs in an actuator, the actuator drive signal is not applied to the faulty actuator due to redundancy, so the solenoid valve maintains a locked state, preventing the driving force of the normally operating actuator from being distributed to the faulty actuator. Also, even if an actuator is selectively turned off, the transmission of driving force to the reducer of the turned-off actuator can be blocked due to the locked state of the solenoid valve.

[0058] Here, when the first lock unit 2310 is locked, the first lock pin 2311 protrudes out of the first lock body 2312, and when it is unlocked, the first lock pin 2311 is retracted into the first lock body 2312. At this time, the first lock pin 2311 in the locked state is engaged with a reducer (which may be, for example, a bevel gear) to prevent rotation of the reducer. Similarly, when the second lock unit 2320 is locked, the second lock pin 2321 protrudes out of the second lock body 2322, and when it is unlocked, the second lock pin 2321 is retracted into the second lock body 2322. At this time, the second lock pin 2321 in the locked state is engaged with a reducer (which may be, for example, a bevel gear) to prevent rotation of the reducer.

[0059] Next, a process in which the controller controls the first actuator 2250 and the second actuator 2260 according to the rack load will be described with reference to FIG.

[0060] FIG. 5 is a flowchart showing a process in which a controller controls the first actuator 2250 and the second actuator 2260 according to the rack load in a steer-by-wire system according to an embodiment of the present invention.

[0061] Referring to Fig. 5, in the steer-by-wire system for a vehicle according to the present invention, the controller can determine the rack load condition when steering the vehicle by referring to the vehicle driving state information (S401). That is, when the vehicle is in a driving state, the load required for steering is small, so the rack load condition can be determined to be equal to or less than a predetermined second load value, and when the vehicle is in a stopped state, the load required for steering is large, so the rack load condition can be determined to exceed a predetermined first load value. Here, the predetermined second load value is greater than the predetermined first load value. small .

[0062] When the vehicle is stopped and the rack load condition exceeds a predetermined first load value, the controller may control (S402) to operate both the first actuator 2250 and the second actuator 2260. In this case, power is supplied to both the first sun gear 2241 and the second sun gear 2242, causing the pinion gear 2230 to rotate, thereby adjusting the steering angle of the vehicle wheels.

[0063] Conversely, when the vehicle is in a traveling state and the rack load condition is equal to or less than a predetermined second load value, a specific one of the first actuator 2250 and the second actuator 2260 can be controlled to adjust the steering angle of the vehicle wheels (S403). That is, power can be supplied to only a specific one of the first sun gear 2241 and the second sun gear 2242 to rotate the pinion gear 2230.

[0064] If a specific actuator fails, the pinion gear 2230 will not rotate at all, making it impossible to steer the vehicle, which may result in an accident. Therefore, the controller detects the momentum of at least some of the rack gear 2220 and pinion gear 2230 from the steering sensor 2270, and if the detected momentum is smaller than the target momentum corresponding to the steering input information by an allowable threshold or more, it can determine that a specific actuator has failed (S404). That is, when the driver performs an input to the steering wheel, if the actual steering of the vehicle is significantly smaller than the steering input information input through the steering wheel, another actuator (e.g., if the first actuator 2250 is controlled but no steering occurs, the second actuator 2260) can be controlled (S405). This allows the steering angle of the vehicle wheels to be adjusted.

[0065] Here, when the controller controls the first actuator 2250 among the first actuator 2250 and the second actuator 2260 to supply power, the first locking unit 2310 is in an unlocked state and the second locking unit 2320 is in a locked state, so that the driving force of the first actuator 2250 is prevented from being transmitted to the second actuator 2260.

[0066] 4, the first lock pin 2311 and the second lock pin 2321 of the first lock unit 2310 and the second lock unit 2320 are respectively positioned on the bevel gears of the first actuator 2250 and the second actuator 2260. According to the example of Fig. 4, when power is supplied from the second actuator 2260 but not from the first actuator 2250, the first lock unit 2310 positioned on the first actuator 2250 side maintains a locked state to prevent the first lock pin 2311 from rotating the bevel gear. Therefore, even when power is supplied from the second actuator 2260, the motor, bevel gear, and first sun gear 2241 on the first actuator 2250 side do not rotate, thereby reducing power loss. 4, the first lock unit 2310 and the second lock unit 2320 are connected to the bevel gears, respectively, but the first lock unit 2310 and the second lock unit 2320 may be installed at any position on the first actuator 2250 and the second actuator 2260, respectively. For example, the first lock unit 2310 may be installed on the motor of the first actuator 2310, and the second lock unit 2320 may be installed on the reducer of the second actuator 2260, but this is not limitative.

[0067] For example, when the controller supplies power to the first actuator 2250 but not to the second actuator 2260, the first locking unit 2310 of the first actuator 2250 is switched to the unlocked state and the first locking pin 2311 is retracted into the first locking body 2312, allowing the first actuator 2250 to rotate, while the second locking unit 2320 of the second actuator 2260 maintains the locked state, preventing the power of the first actuator 2250 from being transmitted to the second actuator 2260. Conversely, when power is supplied to the second actuator 2260, the second locking unit 2320 of the second actuator 2260 is switched to the unlocked state and the second locking pin 2321 is retracted into the second locking body 2322, allowing the second actuator 2260 to rotate, while the first locking unit 2310 of the first actuator 2250 maintains the locked state, preventing the power of the second actuator 2260 from being transmitted to the first actuator 2250.

[0068] While the above description refers to vehicle operation information to determine whether the load condition exceeds a predetermined first load value or is equal to or less than a predetermined second load value, various load conditions according to each operation condition can be set using vehicle operation information, i.e., speed, target wheel angle, etc., and the operation of the actuators and the torque of each actuator can be controlled according to each load condition. Also, the actual vehicle load can be detected through a load sensor, the rack load can be calculated based on the detected vehicle load, and the actuators can be controlled based on the calculated rack load.

[0069] Next, with reference to FIG. 6, a process in which another controller controls the first actuator 2250 and the second actuator 2260 depending on whether a specific controller has failed will be described in the steer-by-wire system according to the present invention.

[0070] FIG. 6 is a flowchart illustrating a process in which a controller controls the first actuator 2250 and the second actuator 2260 depending on whether a specific controller has failed in a steer-by-wire system according to an embodiment of the present invention.

[0071] The steer-by-wire system for a vehicle according to the present invention may include multiple controllers. Referring to Figure 6, a specific controller among the controllers may be configured to control both the first actuator 2250 and the second actuator 2260 (S501). Controllers other than the specific controller may also be configured to control both the first actuator 2250 and the second actuator 2260.

[0072] Here, a specific controller and the other controllers may be configured to transmit and receive operational status information to each other to determine whether a failure has occurred. If the other controllers cannot receive operational status information from the specific controller for a certain period of time, the other controllers may determine that the specific controller has failed (S502). Thereafter, the other controllers may control the first actuator 2250 and the second actuator 2260 in place of the specific controller, thereby adjusting the steering angle of the vehicle wheels (S503).

[0073] The number of controllers is not limited. For example, if there are a first controller, a second controller, and a third controller, the operating state information may be transmitted and received between the first controller and the second controller, between the first controller and the third controller, and between the second controller and the third controller.

[0074] In the steer-by-wire system for a vehicle according to the present invention, the first actuator 2250 may include a first motor that generates power, a first reducer that converts the power generated from the first motor to correspond to a first power value, and a first sun gear shaft that connects the first reducer to the first sun gear 2241. The first reducer may be configured to adjust the power at a certain rate when transmitting the power of the first motor to the first sun gear shaft.

[0075] Similarly, the second actuator 2260 may include a second motor that generates power, a second reducer that converts the power generated by the second motor to correspond to a second power value, and a second sun gear shaft that connects the second reducer to the second sun gear 2242. Similarly, the second reducer may be configured to adjust the power at a certain rate when transmitting the power of the second motor to the second sun gear shaft.

[0076] In one embodiment of the present invention, the first motor may include 1_1 windings to 1_n windings that generate power for the first motor, where n may be an integer of 2 or greater.

[0077] The second motor may include 2_1 windings to 2_n windings that generate power for the second motor, that is, the number of windings of the second motor may be configured to be the same as that of the first motor.

[0078] In this case, the controller includes first through n-th controllers, and when the 1_1 winding and the 2_1 winding are defined as a first winding pair, the first through n-th winding pairs can be connected to and controlled by the first through n-th controllers, respectively. In other words, each of the windings of the first motor and each of the windings of the second motor are paired, and the pair of windings can be controlled by one controller. Therefore, one controller can control one winding of the first motor and one winding of the second motor. This configuration has the advantage that even if a mechanical failure occurs in one of the motor windings, the remaining windings can be controlled to steer the vehicle.

[0079] In another embodiment of the present invention, the first motor may include one first winding for generating power for the first motor.

[0080] Similarly, the second motor may include one second winding that generates power for the second motor, and the controller may include a specific controller and another controller.

[0081] In this case, the first winding and the second winding may be connected to a specific controller and another controller, respectively, i.e., the first winding and the second winding may be controlled by a specific controller at the same time, and may also be controlled by another controller at the same time.

[0082] Here, a specific controller and other controllers may be configured to transmit and receive operational status information to each other to determine a fault. In this case, the number of controllers is not limited. For example, if a first controller, a second controller, and a third controller exist, operational status information may be transmitted and received between the first controller and the second controller, between the first controller and the third controller, and between the second controller and the third controller.

[0083] When a specific controller controls the first winding and the second winding, if the other controllers do not receive operational status information from the specific controller for a certain period of time, it can be determined that the specific controller has failed, and thereafter, the other controllers can be controlled in place of the specific controller to generate power for the first motor and the second motor.

[0084] Although the present invention has been described above using specific details such as specific components and limited examples and drawings, this is merely provided to aid in a more general understanding of the present invention, and the present invention is not limited to the above examples. Those skilled in the art to which the present invention pertains will appreciate that various modifications and variations can be made from such descriptions.

[0085] Therefore, the concept of the present invention should not be limited to the above-described embodiments, and all modifications equivalent to or equivalent to the scope of the claims, as well as the scope of the claims, can be said to fall within the scope of the concept of the present invention.

Claims

1. In a steer-by-wire system for a vehicle, a rack shaft having a rack gear mounted thereon, the rack gear moving linearly to adjust the steering angle of the vehicle wheels; a pinion gear meshed with the rack gear and causing the rack gear to move linearly by its rotational movement; a differential gear module including: a first sun gear and a second sun gear disposed opposite to each other; at least one planetary gear meshed with the first sun gear and the second sun gear and revolving around an orbital axis connecting a center point of the first sun gear and a center point of the second sun gear in response to rotational movement of at least one sun gear among the first sun gear and the second sun gear; and a case rotating around the orbital axis and connected to the pinion gear; a first actuator and a second actuator for rotating the first sun gear and the second sun gear, respectively; at least one controller that controls the first actuator and the second actuator in response to steering input information; and a steering sensor that senses at least a portion of the momentum among the rack gear and the pinion gear; A steer-by-wire device comprising:

2. In a state where a specific controller among the controllers controls the first actuator and the second actuator, 2. The steer-by-wire system according to claim 1, wherein, when another controller other than the specific controller that can control the first actuator and the second actuator does not receive operation status information from the specific controller for a certain period of time, the other controller determines that the specific controller has failed and controls the first actuator and the second actuator in place of the specific controller so that the steering angle of the vehicle wheels is adjusted.

3. 2. The steer-by-wire system of claim 1, wherein the first actuator and the second actuator each include a first locking unit and a second locking unit that lock and unlock the rotation of the first sun gear and the second sun gear, respectively.

4. the first actuator includes a first motor that generates power, a first reducer that converts the power generated by the first motor into a power corresponding to a first power value, and a first sun gear shaft that connects the first reducer and the first sun gear, 2. The steer-by-wire system according to claim 1, wherein the second actuator includes a second motor that generates power, a second reducer that converts the power generated by the second motor to correspond to a second power value, and a second sun gear shaft that connects the second reducer and the second sun gear.

5. the first motor includes 1_1 windings through 1_n windings (where n is an integer of 2 or more) that generate power for the first motor, the second motor includes 2_1 windings through 2_n windings that generate power for the second motor, the controllers include a first controller to an n-th controller, 5. The steer-by-wire system according to claim 4, wherein when the 1_1 winding and the 2_1 winding are defined as a first winding pair, the first through n-th winding pairs are connected to and controlled by the first through n-th controllers, respectively.

6. the first motor includes a first winding that generates power for the first motor; the second motor includes a second winding that generates power for the second motor; The controller includes a specific controller and another controller, With the first winding and the second winding connected to the specific controller and the other controller, respectively, 5. The steer-by-wire system according to claim 4, wherein, when a specific controller among the controllers controls the first winding and the second winding, if another controller other than the specific controller that can control the first winding and the second winding does not receive operation status information from the specific controller for a certain period of time, the specific controller is determined to have failed, and the first winding and the second winding are used to generate power for the first motor and the second motor, respectively.

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