Steering system

Abstract

To improve the anti-theft performance of a vehicle in a steer-by-wire steering system.SOLUTION: There is provided a steer-by-wire steering system 12 mounted on a vehicle 10 which converts the operation of an operation member 20 by a driver into an electrical signal, and controls a turning device 30 mechanically separated from the operation member 20 on the basis of the electrical signal to realize turning of wheels 32. The steering system 12 includes a controller 24. The controller 24 transmits a communication request to a steering lock device 14 mounted on the vehicle 10 when an ignition switch 19 of the vehicle 10 is turned on, and stops control of the turning device 30 when receiving no specific communication response from the steering lock device 14 in response to the communication request.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steer-by-wire steering system mounted on a vehicle. [Background technology]

[0002] Steer-by-wire steering systems, which have no mechanical connection between the steering wheel and the steered wheels, have been known as steering systems installed in vehicles. These steering systems convert the driver's steering wheel movements into electrical signals and, based on these electrical signals, control a steering device that is mechanically separated from the steering wheel to steer the wheels.

[0003] Also, in order to prevent vehicle theft, a steering lock device is known that restricts the movement (rotation, etc.) of steering components such as a steering wheel when the vehicle is parked. Also, a configuration that provides an additional vehicle movement restriction means in preparation for cases where the restriction imposed by the steering lock device is illegally released is being considered (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-162062 Summary of the Invention [Problem to be solved by the invention]

[0005] In a vehicle equipped with a steer-by-wire steering system, for example, if a steering lock device is broken and power is supplied to the steering system for steering operation with the intent of stealing the vehicle, there is a risk that the vehicle may become easily movable. Therefore, it is desired to improve the anti-theft performance of the steer-by-wire steering system. [Means for solving the problem]

[0006] The steering system of the present invention is a steer-by-wire type steering system mounted on a vehicle, which converts the operation of an operating member by a driver into an electrical signal and realizes wheel steering by controlling a steering device mechanically separated from the operating member based on the electrical signal, and is characterized in that it is equipped with a controller, which, when the ignition switch of the vehicle is turned on, sends a communication request to a steering lock device mounted on the vehicle, and if it does not receive a specified communication response from the steering lock device to the communication request, stops control of the steering device.

[0007] According to this configuration, if the steering lock device is destroyed with the intent of stealing the vehicle and the controller does not receive a specified communication response from the steering lock device, the controller stops control of the steering system's turning device, thereby restricting the movement of the vehicle.

[0008] In the steering system of the present invention, the steering lock device may be configured to unlock the steering when the ignition switch of the vehicle is on, and the controller may transmit an inquiry signal regarding the locked / unlocked state of the steering to the steering lock device when a specified communication response is received from the steering lock device in response to the communication request, and may stop control of the turning device if a signal indicating an unlocked state is not received from the steering lock device in response to the inquiry signal.

[0009] According to this configuration, if the communication function of the steering lock device is normal but the actuator, locking mechanism, sensor, etc. of the steering lock device are destroyed and the controller does not receive a signal from the steering lock device indicating an unlocked state, the controller stops control of the steering system's turning device, thereby restricting the movement of the vehicle.

[0010] In the steering system according to the present invention, the steering lock device may be configured to encrypt an original signal and transmit an encrypted signal to the controller, and the controller may be configured to receive the encrypted signal and decrypt it to obtain the original signal.

[0011] This configuration is intended to deal with a case where, for example, a steering lock device is destroyed and a dummy device impersonating the original device is installed, and the dummy device transmits a dummy communication response or a signal indicating an unlocked state to the controller. According to the above configuration, the dummy device transmits, for example, an unencrypted signal, so that the controller does not acquire (receive) the specified communication response or signal indicating an unlocked state, and the controller can stop control of the steering device of the steering system and restrict the movement of the vehicle.

[0012] In the steering system of the present invention, the steering lock device is configured to transmit to the controller a signal with an authentication code, which is an original signal with an authentication code added thereto, and the controller is configured to receive the signal with the authentication code and authenticate the original signal using the authentication code of the signal to confirm that the sender of the signal with the authentication code is the steering lock device, and if the controller cannot confirm that the sender is the steering lock device through the authentication, it may stop control of the turning device.

[0013] This configuration also addresses the situation where, for example, the steering lock device is destroyed and a dummy device is installed, transmitting a signal indicating a dummy communication response or an unlocked state to the controller. The dummy device may, for example, transmit a signal without an authentication code, or transmit a signal with an authentication code different from the authentication code added by the steering lock device. In this case, the above configuration allows the controller to recognize that the signal sender is a device other than the steering lock device, and therefore the controller can stop control of the steering device of the steering system and restrict the movement of the vehicle. [Effects of the Invention]

[0014] According to the present invention, it is possible to improve the anti-theft performance of a vehicle in a steer-by-wire type steering system. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic block diagram showing a configuration related to a steering system of a vehicle. [Figure 2] 4 is a flowchart showing a start-up process of the steering system. [Figure 3A] FIG. 4 is a diagram showing a signal flow in the start-up process of the steering system. [Figure 3B] FIG. 10 is a diagram showing another signal flow in the start-up process of the steering system. [Figure 4A] FIG. 10 is a diagram showing the signal flow of the start-up process of the steering system using encrypted communication or authentication communication. [Figure 4B] FIG. 10 is a diagram showing another signal flow in the start-up process of the steering system using encrypted communication or authenticated communication. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described herein. The same elements in all the drawings are designated by the same reference numerals, and redundant explanations will be omitted.

[0017] FIG. 1 is a schematic block diagram showing the configuration related to a steering system 12 of a vehicle 10. The vehicle 10 may be, for example, an engine vehicle, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The type of vehicle is not limited. The vehicle 10 of this embodiment has two front wheels and two rear wheels, with the two front wheels being steered wheels 32. The vehicle 10 includes a start switch unit 16, a verification ECU 18, an ignition switch 19 (hereinafter referred to as the IG switch 19), a transceiver 50, a steering system 12, and a steering lock device 14.

[0018] The start switch unit 16 includes a start switch 17 provided at a position operable from the driver's seat inside the vehicle 10. The start switch 17 is, for example, a push-button switch.

[0019] The verification ECU 18 is a computer that verifies the key information of the smart key 90 against pre-registered key information. The transceiver 50 is connected to the verification ECU 18. When a user carrying the smart key 90 is inside the vehicle 10, the smart key 90 receives a predetermined radio wave transmitted from the transceiver 50 and transmits the key information. The key information transmitted from the smart key 90 is then received by the transceiver 50. When the transceiver 50 receives the key information, the verification ECU 18 verifies the received key information against pre-registered key information.

[0020] When the received key information matches the pre-registered key information and the user turns on the start switch 17 while depressing the brake pedal (not shown), the verification ECU 18 transitions the IG switch 19 to the ON state, which turns on the ignition power supply and supplies power to the steering system 12 and the steering lock device 14 from a battery (not shown).

[0021] The steering system 12 is a steer-by-wire type steering system that converts the operation of the steering wheel 20 by the driver into an electrical signal and controls a steering actuator 30 that is mechanically separated from the steering wheel 20 based on the electrical signal, thereby steering the wheels 32.

[0022] The steering system 12 includes a steering wheel 20 as an operating member, an operation angle sensor 22, a steer-by-wire ECU 24, and a steering actuator 30. The steering actuator 30 is an example of a steering device.

[0023] The operation angle sensor 22 detects the operation angle of the steering wheel 20 as the operation amount of the steering wheel 20 .

[0024] The steer-by-wire ECU 24 is a controller for the steering system 12. The steer-by-wire ECU 24 includes an operation ECU 26 and a steering ECU 28, which may be integrated or physically separated.

[0025] Operation ECU 26 acquires the operation angle of steering wheel 20 from operation angle sensor 22 and transmits it to steering ECU 28. Steering ECU 28 receives the operation angle from operation ECU 26 and multiplies the operation angle by the steering gear ratio to determine a target steering angle that is a target for the steering angle of road wheels 32. The steering gear ratio is the ratio of the steering angle of road wheels 32 to the operation angle of steering wheel 20. Steering ECU 28 controls steering actuator 30 (hereinafter referred to as steering ACT) so that the steering angle of road wheels 32 becomes the target steering angle.

[0026] Note that in this specification and drawings, a description of the detailed configuration (control, components, etc.) of a steer-by-wire type steering system that is not closely related to the embodiment will be omitted. For example, the operation ECU 26 is configured to perform reaction force control that applies an operation reaction force to the steering wheel 20 so that the driver feels an appropriate steering feel in response to the steering operation. A detailed configuration example of a steer-by-wire type steering system is shown in, for example, Japanese Patent Application Laid-Open No. 2022-149717.

[0027] The steering lock device 14 is a device that restricts the operation (rotation, etc.) of steering components such as the steering wheel 20 when the vehicle 10 is parked in order to prevent theft of the vehicle 10. The steering lock device 14 includes a steering lock ECU 40 (hereinafter referred to as the steering lock ECU 40), a steering lock actuator 42 (hereinafter referred to as the steering lock ACT 42), and an unlock detection sensor 48.

[0028] The steering ECU 40 is a controller that controls the steering ACT 42. The steering ACT 42 is, for example, an electric motor, and operates the locking mechanism 46 based on a control signal from the steering ECU 40. The locking mechanism 46 is configured to be able to selectively form a state in which steering operation is restricted (locked state) and a state in which steering operation restriction is released (unlocked state). The unlock detection sensor 48 is a detection device that detects the unlocked state of the steering. The detection result of the unlock detection sensor 48 is input to the steering ECU 40.

[0029] The start switch unit 16, the verification ECU 18, the steer-by-wire ECU 24, and the steer-by-wire ECU 40 are connected to one another via a communication bus 60. The devices connected to the communication bus 60 are configured to be able to communicate with one another via in-vehicle network communication.

[0030] Here, we will explain on-board ECUs (Electronic Control Units) such as the verification ECU 18, the steer-by-wire ECU 24, and the steer-by-wire ECU 40. The ECU is configured to include a microcomputer. The ECU has a processor such as a CPU, a memory, and an input / output interface (none of which are shown). The memory is RAM (Random Access Memory), ROM (Read Only Memory), a non-volatile storage device (e.g., flash memory), etc. The processor uses the RAM to perform processing in accordance with programs and data previously stored in the ROM or non-volatile storage device, thereby enabling the ECU to realize various controls and functions. Note that the ECU may be configured to include multiple computers, either integrated or physically separated.

[0031] Next, a description will be given of the start-up process of the steering system 12. Fig. 2 is a flowchart showing the start-up process of the steering system 12.

[0032] When a user carrying a smart key 90 (see FIG. 1) enters the vehicle while the vehicle is parked, key information is received by the transceiver 50. If the received key information matches pre-registered key information and the user turns on the start switch 17 while depressing the brake pedal (not shown), the verification ECU 18 transitions the IG switch 19 to the on state. As a result, power is supplied to the steering system 12 and the steering lock device 14, as shown in S100 and S102 of FIG. 2.

[0033] It is also possible that, with the intent of stealing a vehicle, the IG switch 19 may be fraudulently turned on using a transmitter that transmits dummy key information, or that the IG switch 19 or the ignition power supply circuit may be fraudulently tampered with, forcing power to be supplied to the steering system 12.

[0034] Next, in S104 of FIG. 2, the steer-by-wire ECU 24 starts communication with the steer lock ECU 40. Specifically, the steer-by-wire ECU 24 transmits a communication request to the steer lock ECU 40, which receives it. When the steer lock ECU 40 receives the communication request from the steer-by-wire ECU 24, it transmits a specified communication response to the steer-by-wire ECU 24. When the steer-by-wire ECU 24 receives the specified communication response from the steer-by-wire ECU 40, it determines that communication with the steering lock device is normal (S106: Yes) and proceeds to S108.

[0035] On the other hand, if the steer-by-wire ECU 24 does not receive the specified communication response from the steering lock ECU 40 in S106, it determines that communication with the steering lock device is abnormal (S106: No) and proceeds to S116. Then, in S116, the steer-by-wire ECU 24 stops activation of the steering system 12. Specifically, the steer-by-wire ECU 24 stops control of the steering ACT30.

[0036] According to this configuration, if the steering lock device 14 is destroyed with the intent of stealing the vehicle and the steer-by-wire ECU 24 does not receive a specified communication response from the steer lock ECU 40, the steer-by-wire ECU 24 stops control of the steering ACT 30, thereby restricting the movement of the vehicle 10.

[0037] If S106 is Yes (if the communication is normal), in S108, the steer-by-wire ECU 24 transmits a request to release the steering lock to the steer lock ECU 40. Note that this request may be transmitted from the verification ECU 18.

[0038] When the steering ECU 40 receives the steering lock release request (S108), it controls the steering ACT 42 to transition the steering from a locked state to an unlocked state.

[0039] In S110, the steer-by-wire ECU 24 checks whether the steering is unlocked. Specifically, the steer-by-wire ECU 24 transmits an inquiry signal regarding the locked / unlocked state of the steering to the steer-by-wire ECU 40, and the steer-by-wire ECU 40 receives the inquiry signal. Upon receiving the inquiry signal from the steer-by-wire ECU 24, the steer-by-wire ECU 40 transmits a signal indicating the locked or unlocked state of the steering to the steer-by-wire ECU 24. The locked or unlocked state of the steering is detected by the unlock detection sensor 48. When the steer-by-wire ECU 24 receives a signal indicating the unlocked state from the steer-by-wire ECU 40 (S110: Yes), the process proceeds to S112. Then, in S112, adjustments and corrections are made to various parts of the steering system 12 as an initial process, and the startup process of the steering system is completed.

[0040] On the other hand, if the steer-by-wire ECU 24 does not receive a signal indicating the unlocked state from the steer lock ECU 40 at S110 (S110: No), it repeatedly transmits a signal inquiring about the locked / unlocked state (S110) until a certain time has elapsed (S114), and waits for reception of a signal indicating the unlocked state. If the steer-by-wire ECU 24 does not receive a signal indicating the unlocked state even after the certain time has elapsed (S114; Yes), the steer-by-wire ECU 24 proceeds to S116. Then, at S116, the steer-by-wire ECU 24 stops activation of the steering system 12. Specifically, the steer-by-wire ECU 24 stops control of the steering ACT30.

[0041] According to this configuration, even if the communication function of the steering lock device 14 is normal (S106: Yes), if the actuator 42, lock mechanism 46, sensor 48, etc. of the steering lock device 14 are destroyed with the intent of stealing the vehicle and the steer-by-wire ECU 40 is unable to send a signal indicating the unlocked state, the steer-by-wire ECU 24 stops control of the steering ACT30, thereby restricting the movement of the vehicle in case of vehicle theft.

[0042] In the above-described embodiment, the communication between the steer-by-wire ECU 24 and the steer-by-wire ECU 40 may be performed via the verification ECU 18 as shown in FIG. 3A, or may be performed directly between the two ECUs 24, 40 as shown in FIG. 3B.

[0043] Next, another embodiment will be described. As another embodiment, as shown in Figures 4A and 4B, encrypted communication or authenticated communication may be used for communication of a signal from the steer-by-wire ECU 40A to the steer-by-wire ECU 24A. Figures 4A and 4B correspond to Figures 3A and 3B, respectively.

[0044] For example, the steer-by-wire ECU 40A may be configured to encrypt an original signal (a communication response or a signal indicating a locked / unlocked state) and transmit the generated encrypted signal to the steer-by-wire ECU 24A, and the steer-by-wire ECU 24A may be configured to receive the encrypted signal, decrypt it, and obtain the original signal.

[0045] This configuration is intended to deal with a case where, for example, the steering lock device 14 (see FIG. 1) is destroyed with the intent of stealing the vehicle, and a dummy device is installed to impersonate the original device, and a signal indicating a dummy communication response or an unlocked state is transmitted from the dummy device to the steer-by-wire ECU 24A. With this configuration, the dummy device transmits, for example, an unencrypted signal, which prevents the steer-by-wire ECU 24A from receiving the prescribed communication response or signal indicating the unlocked state (S106: No, S114: Yes in FIG. 2), and the steer-by-wire ECU 24A stops control of the steering ACT30 (S116), thereby restricting the movement of the vehicle 10.

[0046] Furthermore, for example, the steer-by-wire ECU 40A may be configured to transmit an authentication-coded signal, which is an original signal (a communication response or a signal indicating a locked / unlocked state) with an authentication code added thereto, to the steer-by-wire ECU 24A, and the steer-by-wire ECU 24A may be configured to receive the authentication-coded signal and authenticate the original signal using the authentication code of the signal to confirm that the sender of the authentication-coded signal is the steer-by-wire ECU 40A. If the steer-by-wire ECU 24A cannot confirm that the sender of the signal is the steer-by-wire ECU 40A through this authentication, it may stop control of the steering ACT 30. Note that a message authentication code (MAC), for example, can be used for this authentication communication.

[0047] This configuration also addresses the case where, for example, the steering lock device 14 (see FIG. 1) is destroyed with the intent of vehicle theft, and a dummy device is installed, transmitting a signal indicating a dummy communication response or an unlocked state from the dummy device to the steer-by-wire ECU 24A. The dummy device may, for example, transmit a signal without an authentication code attached, or transmit a signal to which an authentication code different from the authentication code attached by the steer-by-wire ECU 40A is attached. In this case, with the above configuration, the steer-by-wire ECU 24A can recognize that the signal sender is a device different from the steer-by-wire ECU 40A, and therefore the steer-by-wire ECU 24 can stop control of the steering ACT 30 and restrict the movement of the vehicle. [Explanation of symbols]

[0048] 10 vehicle, 12 steering system, 14 steering lock device, 16 start switch unit, 17 start switch, 18 verification ECU, 19 ignition switch (IG switch), 20 steering wheel (operating member), 22 operation angle sensor, 24, 24A steer-by-wire ECU (controller, ECU), 26 operation ECU, 28 turning ECU, 30 turning actuator (turning ACT, steering device), 32 wheel (turning wheel), 40, 40A steering lock ECU (sterok ECU, ECU), 42 steering lock actuator (sterok ACT), 46 lock mechanism, 48 unlock detection sensor (sensor), 50 transceiver, 60 communication bus, 90 smart key.

Claims

1. A steer-by-wire steering system mounted on a vehicle, which converts the operation of an operating member by a driver into an electrical signal, and controls a steering device mechanically separated from the operating member based on the electrical signal, thereby realizing steering of wheels, Equipped with a controller, When an ignition switch of the vehicle is turned on, the controller transmits a communication request to a steering lock device mounted on the vehicle, and when a specified communication response to the communication request is not received from the steering lock device, the controller stops control of the steering device. A steering system characterized by:

2. 2. A vehicle steering system according to claim 1, the steering lock device is configured to unlock the steering when the ignition switch of the vehicle is on, The controller When a predetermined communication response is received from the steering lock device in response to the communication request, an inquiry signal regarding the locked / unlocked state of the steering is transmitted to the steering lock device, and when a signal indicating the unlocked state is not received from the steering lock device in response to the inquiry signal, control of the turning device is stopped. A steering system characterized by:

3. 3. A vehicle steering system according to claim 1 or 2, the steering lock device is configured to encrypt an original signal and transmit the encrypted signal to the controller; the controller is configured to receive and decrypt the encrypted signal to obtain the original signal. A steering system characterized by:

4. 3. A vehicle steering system according to claim 1 or 2, the steering lock device is configured to transmit an authentication code-added signal obtained by adding an authentication code to an original signal to the controller, the controller is configured to receive the signal with the authentication code, and authenticate an original signal using the authentication code of the signal, thereby confirming that the sender of the signal with the authentication code is the steering lock device, When the controller cannot confirm that the transmission source is the steering lock device through the authentication, the controller stops control of the steering device. A steering system characterized by:

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