Signal transmission method and system for improving usability of steer-by-wire system

Abstract

The invention discloses a signal transmission method and system for a steer-by-wire system, and the method comprises the steps: carrying out the signal fusion through inter-board communication and public CAN communication when a signal in a public CAN line where four control processing units interact with a whole vehicle CAN fails, and obtaining a signal; when the signal of the private CAN line interacted by the two master side MCUs or the signal of the private CAN line interacted by the two slave side MCUs is invalid, performing signal fusion by adopting private CAN communication and public CAN communication to obtain a signal; when the signals of the private CAN line interacted by the two master side MCUs and the private CAN line interacted by the two slave side MCUs are invalid, acquiring the signals by adopting a public CAN communication mode; and when signal failure occurs in inter-board communication between the master MCU and the slave MCU, a public CAN communication mode is adopted to acquire signals. When the signal fails, the steer-by-wire system can obtain the available signal from other transmission paths so as to maintain the normal enabling of the software function, ensure the normal response of the steering function, and improve the availability of the steer-by-wire system and the safety of signal transmission.

Description

Technical Field

[0001] This invention relates to the field of steer-by-wire (SBW) systems, specifically to a signal transmission method and system for improving the usability of steer-by-wire systems. Background Technology

[0002] The steer-by-wire system comprises an upper steering system and a lower steering system, each further subdivided into a primary steering system and a secondary steering system, totaling four control processing units. For example... Figure 1 As shown, in the current traditional steer-by-wire system, the upper steering system interacts with the vehicle's CAN bus via a common CAN communication 1, while the lower steering system interacts with the vehicle's CAN bus via a common CAN communication 2.

[0003] With the increasing demand for intelligent driving from customers, more and more advanced functions are being developed. To provide a comfortable driving experience, it is crucial to achieve precise control of the vehicle's ADAS (Advanced Driving Assistance System) and ensure the availability of the steer-by-wire system. Therefore, customers have placed higher demands on steering suppliers, requiring not only that the four control processing units in the steer-by-wire system transmit complete system status information, but also that the steering system maintain availability in the event of certain failures—that is, when one signal fails, the steering function must still respond normally. This presents a significant challenge, considering the complex internal communication signals within the system, and how the software application modules can correctly select signals and improve the overall availability and safety of the system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a signal transmission method and system for a steer-by-wire system, which can avoid the problem of the steer-by-wire system failing to operate normally due to signal failure, and improve the availability and safety of the steer-by-wire system.

[0005] To address the aforementioned problems, this invention provides a signal transmission system for improving the usability of a steer-by-wire system. The steer-by-wire system includes an upper steering system, a vehicle signal processing system, and a lower steering system. The upper steering system is configured with an upper steering master MCU and an upper steering slave MCU, and the lower steering system is configured with a lower steering master MCU and a lower steering slave MCU, wherein:

[0006] The upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU and the vehicle signal processing system interact with the vehicle CAN line through different common CAN lines. The common CAN line is used to transmit the interaction signals between the vehicle and the steer-by-wire system.

[0007] The upper steering master MCU and the upper steering slave MCU, and the lower steering master MCU and the lower steering slave MCU interact through inter-board communication, which is used to transmit the interaction signals between the master MCU and the slave MCU.

[0008] The upper steering master MCU and the lower steering master MCU, as well as the upper steering slave MCU and the lower steering slave MCU, communicate via private CAN lines. The private CAN lines are used to transmit the interaction signals between the drive-by-wire upper steering system and the lower steering system.

[0009] The upper steering master MCU and the lower steering master MCU form a master-master channel, and the upper steering slave MCU and the lower steering slave MCU form a slave-slave channel. The system prioritizes upper and lower steering control through the master-master channel, and the slave channel provides backup for upper and lower steering signals. A UART1 channel is set between the upper steering master MCU and the upper steering slave MCU, and a UART2 channel is set between the lower steering master MCU and the lower steering slave MCU. The system provides backup for the upper and lower steering master-slave signals through the UART1 channel and the UART2 channel, respectively.

[0010] Furthermore, the present invention also provides a signal transmission method using the aforementioned signal transmission system for improving the availability of the steer-by-wire system, wherein:

[0011] When the signal in the common CAN line of the upper steering system and / or lower steering system fails, the signal is obtained by inter-board communication or common CAN communication.

[0012] When the private CAN line between the upper steering master MCU and the lower steering master MCU or the private CAN line between the upper steering slave MCU and the lower steering slave MCU fails to transmit signals, the signal is obtained by using either private CAN communication or public CAN communication.

[0013] When both the private CAN line between the upper steering master MCU and the lower steering master MCU and the private CAN line between the upper steering slave MCU and the lower steering slave MCU fail to transmit signals simultaneously, the common CAN communication method is used to obtain the signal.

[0014] When signal transmission fails during inter-board communication between the upper steering master MCU and the upper steering slave MCU and / or between the lower steering master MCU and the lower steering slave MCU, the common CAN communication method is used to obtain the signal.

[0015] Furthermore, signal failure in the common CAN lines of the upper steering system and / or lower steering system includes signal transmission failure of any one, two, or three common CAN lines that interact with the vehicle CAN bus of the upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU, and the vehicle CAN bus.

[0016] Furthermore, when a signal fails in the common CAN line of the upper steering system and / or lower steering system, the required corresponding signal is obtained according to the path of inter-board communication + common CAN line or the path of common CAN line + private CAN line.

[0017] Furthermore, when a signal transmission failure occurs on the private CAN line between the upper steering master MCU and the lower steering master MCU, or on the private CAN line between the upper steering slave MCU and the lower steering slave MCU, the required corresponding signal is obtained according to the path of the private CAN line + inter-board communication or the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

[0018] Furthermore, when the private CAN line between the upper steering master MCU and the lower steering master MCU and the private CAN line between the upper steering slave MCU and the lower steering slave MCU both fail to transmit signals simultaneously, the required corresponding signal is obtained by using the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

[0019] Furthermore, when the inter-board communication between the upper steering master MCU and the upper steering slave MCU fails to transmit signals, the upper steering master MCU and the upper steering slave MCU obtain signals through the path composed of the two common CAN lines that the upper steering system interacts with the vehicle and the vehicle CAN line.

[0020] When the inter-board communication between the lower steering master MCU and the lower steering slave MCU fails to transmit signals, the lower steering master MCU and the lower steering slave MCU obtain signals through the path composed of the two common CAN lines that the lower steering system interacts with the vehicle and the vehicle CAN line.

[0021] Furthermore, the path of inter-board communication + public CAN line has a higher priority than the path of public CAN line + private CAN line.

[0022] Furthermore, the path of private CAN line + inter-board communication has a higher priority than the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

[0023] Compared with the prior art, the technical effects that the present invention can produce are as follows:

[0024] First, the four control processing units (MCUs) in the upper and lower steering systems of this invention interact with the vehicle CAN line through a common CAN line, and the upper and lower steering systems interact through two private CAN lines. The master MCU and the slave MCU interact through UART. This ensures that the four control processing units in the steer-by-wire system can send out complete system status information, and that when some signals fail, the steer-by-wire system can obtain available signals from other transmission paths to maintain the normal enabling of software functions and ensure normal response of the steering function.

[0025] Secondly, the signal transmission method of the present invention enhances the usability of the steer-by-wire system software function, realizes precise control of the vehicle's ADAS function, and provides customers with a better intelligent driving experience; at the same time, by prioritizing and fusing multiple input signals for output, the software architecture design reduces the interfaces for software element interaction, making the data flow clearer.

[0026] Third, the present invention adopts a hardware dual-channel and software security algorithm implementation method to ensure signal security redundancy and greatly improve the security of the steer-by-wire system at the signal transmission level. Attached Figure Description

[0027] Figure 1 This is a flow diagram of the signal transmission path in a traditional steer-by-wire system.

[0028] Figure 2 This is a flow diagram of the signal transmission path of the steer-by-wire system of the present invention;

[0029] Figure 3 This is a diagram showing the signal transmission path when the signal on the common CAN line 1 fails in this invention.

[0030] Figure 4 This is a flowchart illustrating the signal acquisition process when the signal of the common CAN line 1 fails in this invention.

[0031] Figure 5 This is a diagram showing the signal transmission path when the private CAN line 1 signal fails in this invention.

[0032] Figure 6 This is a flowchart illustrating the signal acquisition process when the private CAN line 1 signal fails in this invention.

[0033] Figure 7 This is a diagram showing the signal transmission path when the inter-board communication 1 signal fails in this invention.

[0034] Figure 8 This is a flowchart illustrating the signal acquisition process when the inter-board communication signal 1 fails in this invention. Detailed Implementation

[0035] The embodiments of the present invention are described below with reference to the accompanying drawings and specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications. Those skilled in the art can make various similar extensions and substitutions without departing from the spirit of the present invention.

[0036] This invention provides a signal transmission system to improve the usability of a steer-by-wire system. The steer-by-wire system includes an upper steering system, a vehicle signal processing system, and a lower steering system. The upper steering system is equipped with an upper steering master MCU and an upper steering slave MCU, and the lower steering system is equipped with a lower steering master MCU and a lower steering slave MCU. Figure 1 As shown. According to the composition of the steer-by-wire system, in order to realize the "lower follows upper" function of the steer-by-wire system, the upper steering system in the transmission system of this invention sends a control request command through private CAN communication, and the lower steering system receives the command and outputs motor force to drive the wheels to rotate.

[0037] like Figure 2 As shown, the upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU, and the vehicle signal processing system interact with the vehicle CAN bus via different common CAN lines. The common CAN bus is used to transmit interaction signals between the vehicle and the steer-by-wire system, such as vehicle speed signals and system status signals transmitted by the steer-by-wire system. The upper steering master MCU and the upper steering slave MCU, as well as the lower steering master MCU and the lower steering slave MCU, interact via inter-board communication. Inter-board communication is used to transmit interaction signals between the master and slave MCUs, such as power assist request torque control command signals and key signals transmitted via the private CAN bus between the steer-by-wire upper and lower steering systems. The upper steering master MCU and the lower steering master MCU, as well as the upper steering slave MCU and the lower steering slave MCU, interact via private CAN bus. The private CAN bus is used to transmit interaction signals between the steer-by-wire upper and lower steering systems, such as the request angle signal calculated by the upper steering system, the rack position signal calculated by the lower steering system, and key signals transmitted via the common CAN bus.

[0038] like Figure 2As shown, in terms of hardware configuration, the steer-by-wire system employs dual-channel signal backup. Four control processing units (upper steering master MCU, upper steering slave MCU, lower steering master MCU, and lower steering slave MCU) transmit signals via independent common CAN lines 1-4. The upper and lower steering master MCUs form a master-master channel via private CAN line 1, and the upper and lower steering slave MCUs form a slave-slave channel via private CAN line 2. The steer-by-wire system prioritizes up and down steering control via the master-master channel, with the slave channel providing up and down steering signal backup. The upper and upper steering slave MCUs establish inter-board communication 1 via UART1, and the lower steering master MCU and lower steering slave MCU establish inter-board communication 2 via UART2. The system performs up and down steering master-slave signal backup via UART1 and UART2, respectively. When the transmitted signal is normal, the signal transmission uses the master channel as the primary channel; when the private CAN line 1 signal fails, the signal transmission channel switches to the slave channel to achieve signal redundancy and improve the availability of the entire system.

[0039] Considering that the signals transmitted by the two channels are the same, in order to achieve security redundancy in software heterogeneity, the steer-by-wire system of this invention adopts a dual-code mode, that is, the code of the two channels is developed by different development teams, and the signal transmission verification of the two channels adopts two different CRC verification algorithms (sequential XOR verification, reverse XOR verification, etc.), which can improve the security of the steer-by-wire system in communication interaction.

[0040] This invention also provides the use of Figure 2 The signal transmission system shown here, used to improve the usability of the steer-by-wire system, mainly includes the following three methods:

[0041] Case 1: When the signal in the common CAN line of the upper steering system and / or lower steering system fails, the signal is obtained by inter-board communication or common CAN communication.

[0042] Scenario 2: When the private CAN line between the upper steering master MCU and the lower steering master MCU or the private CAN line between the upper steering slave MCU and the lower steering slave MCU fails to transmit signals, the signal is obtained using either private CAN communication or public CAN communication. When both the private CAN line between the upper steering master MCU and the lower steering master MCU and the private CAN line between the upper steering slave MCU and the lower steering slave MCU fail to transmit signals simultaneously, the signal is obtained using public CAN communication.

[0043] Case 3: When signal transmission fails during inter-board communication between the upper steering master MCU and the upper steering slave MCU and / or between the lower steering master MCU and the lower steering slave MCU, the common CAN communication method is used to obtain the signal.

[0044] In scenario 1, a signal failure in the common CAN bus of the upper steering system and / or lower steering system includes a signal transmission failure on any one, two, or three common CAN bus lines interacting with the vehicle's CAN bus, including the upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU, and the vehicle's CAN bus. Figure 2 As shown, the failure scenarios include: common CAN line 1 failure, common CAN line 2 failure, common CAN line 3 failure, common CAN line 4 failure, simultaneous failure of common CAN lines 1 and 2, simultaneous failure of common CAN lines 3 and 4, simultaneous failure of common CAN lines 1 and 4, simultaneous failure of common CAN lines 2 and 3, and any three of the following common CAN lines failing: common CAN line 1, common CAN line 2, common CAN line 3, and common CAN line 4. When a common CAN line transmission signal fails, the required signal is obtained based on either the inter-board communication + common CAN line path or the common CAN line + private CAN line path. The path selection priority is based on the internal system priority, therefore the inter-board communication + common CAN line path has a higher priority than the common CAN line + private CAN line path.

[0045] In scenario 2, when signal transmission fails on either private CAN line 1 between the upper steering master MCU and the lower steering master MCU, or private CAN line 2 between the upper steering slave MCU and the lower steering slave MCU, the required signal is obtained based on the path formed by the private CAN line + inter-board communication, or the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system. The path selection prioritizes the upper system and the lower steering system internal paths; therefore, the path of private CAN line + inter-board communication has a higher priority than the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system. When both private CAN line 1 between the upper steering master MCU and the lower steering master MCU, and private CAN line 2 between the upper steering slave MCU and the lower steering slave MCU experience signal transmission failure simultaneously, the required signal is obtained using the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

[0046] In scenario 3, when the inter-board communication 1 between the upper steering master MCU and the upper steering slave MCU fails to transmit signals, both the upper steering master MCU and the upper steering slave MCU acquire signals through a path composed of the two common CAN lines used for interaction between the upper steering system and the vehicle, as well as the vehicle CAN line. Similarly, when the inter-board communication 1 between the upper steering master MCU and the lower steering slave MCU fails to transmit signals, both the lower steering master MCU and the lower steering slave MCU acquire signals through a path composed of the two common CAN lines used for interaction between the lower steering system and the vehicle, as well as the vehicle CAN line. When both inter-board communication 1 between the upper steering master MCU and the upper steering slave MCU, and inter-board communication 2 between the lower steering master MCU and the lower steering slave MCU simultaneously fail to transmit signals, both the upper steering master MCU and the upper steering slave MCU acquire signals through a path composed of the two common CAN lines used for interaction between the upper steering system and the vehicle, as well as the vehicle CAN line.

[0047] The following examples illustrate the signal transmission path selection and fusion methods when the above three signal transmission failures occur.

[0048] Figure 3 The diagram illustrates a scenario where signal transmission fails on common CAN line 1, the communication route between the upper steering MCU and the vehicle's CAN bus. For example, if the vehicle speed signal is lost, a traditional steer-by-wire system would use the default vehicle speed for power steering output, resulting in inconsistent power steering output regardless of operating conditions and a poor user experience. In this situation, to ensure normal software functionality, this embodiment uses inter-board communication or common CAN communication for signal acquisition. When signal transmission fails on common CAN line 1, such as… Figure 3 As shown, the MCU on the upper steering main side can still obtain signals through path 1 (common CAN line 2 + inter-board communication 1) or path 2 (common CAN line 3 + private CAN line 1), allowing the speed-adjustable assist function to operate normally and greatly improving system availability. In this embodiment, path 1 is preferred for obtaining the required signal. When path 1 fails to transmit the signal, path 2 is used to obtain the required signal.

[0049] like Figure 4 As shown, the signal acquisition process when the common CAN line 1, which is used for communication between the upper steering main MCU and the vehicle CAN line, fails to transmit signals includes the following steps:

[0050] Step 1: Determine whether the signal received by the main MCU on the up-turning side originates from common CAN line 1. If yes, proceed to step 2; otherwise, end the process.

[0051] Step 2: Determine whether the signal received by the main MCU of the up-turn switch is valid. If it is, select common CAN line 1 as the signal output channel and end; otherwise, proceed to step 3.

[0052] Step 3: Determine whether the signal transmitted by inter-board communication 1 is valid. If it is, select inter-board communication 1 as the signal output channel, obtain the signal from the transmission path of common CAN line 2 + inter-board communication 1, and end; otherwise, proceed to step 4.

[0053] Step 4: Determine whether the signal transmitted by private CAN line 1 is valid. If it is, select private CAN line 1 as the signal output channel, obtain the signal from the transmission path of public CAN line 3 + private CAN line 1, and end. If not, output an invalid signal value and end.

[0054] Other scenarios are not listed here. Only the cases where two common CAN lines fail simultaneously and the cases where three common CAN lines fail simultaneously are briefly explained below:

[0055] When both common CAN line 1 and common CAN line 3 fail to transmit signals, the MCU on the upper steering side can still obtain signals through path 1 (common CAN communication 2 + inter-board communication 1) and path 2 (common CAN communication 4 + inter-board communication 2 + private CAN communication 1).

[0056] When common CAN line 1, common CAN line 2 and common CAN line 3 fail simultaneously, the MCU on the upper steering side can still obtain signals through path 1 (common CAN communication 4 + inter-board communication 2 + private CAN communication 1) and path 2 (common CAN communication 4 + private CAN communication 2 + inter-board communication 1).

[0057] like Figure 5 The diagram illustrates a scenario where signal transmission fails on the private CAN line 1, which facilitates interaction between the upper and lower steering master MCUs. For example, if the requested angle signal calculated by the upper steering system fails, in a traditional steer-by-wire system, the lower steering system cannot acquire this signal. In high-speed driving scenarios, this can lead to the upper steering system being unable to control the lower steering system to rotate the wheels, causing loss of vehicle control and posing a significant safety hazard. To ensure normal software functionality, this embodiment employs either private communication or public CAN communication for signal acquisition. When a signal transmission failure occurs on private CAN line 1, such as… Figure 5As shown, the MCU on the lower steering side can still obtain signals through path 1 (private CAN line 2 + inter-board communication 2) or path 2 (common CAN line 1 + vehicle CAN line + common CAN line 3), avoiding the risk of vehicle loss of control and greatly improving system availability. In this embodiment, path 1 is preferred to obtain the required signal. When path 1 fails to transmit the signal, path 2 is used to obtain the required signal.

[0058] like Figure 6 As shown, the signal acquisition process when the private CAN line 1, which facilitates communication between the upper steering main MCU and the lower steering main MCU, fails to transmit signals includes the following steps:

[0059] Step 1: Determine whether the signal received by the MCU on the steering main side originates from private CAN line 1. If yes, proceed to step 2; otherwise, end the process.

[0060] Step 2: Determine if the signal received by the main MCU of the steering wheel is valid. If it is, select private CAN line 1 as the signal output channel and end; otherwise, proceed to step 3.

[0061] Step 3: Determine if the signal transmitted by inter-board communication 2 is valid. If it is, select inter-board communication 2 as the signal output channel, obtain the signal from the transmission path of private CAN line 2 + inter-board communication 2, and end. If not, proceed to step 4.

[0062] Step 4: Determine if the signal transmitted by common CAN line 3 is valid. If it is, select common CAN line 3 as the signal output channel, obtain the signal from the transmission path of common CAN line 1 + vehicle CAN line + common CAN line 3, and end. If not, output an invalid signal value and end.

[0063] When both private CAN line 1 between the upper steering master MCU and the lower steering master MCU, and private CAN line 2 between the upper steering slave MCU and the lower steering slave MCU fail to transmit signals simultaneously, the lower steering master MCU can still obtain signals through the path (common CAN line 1 + vehicle CAN line + common CAN line 3), and the lower steering slave MCU can obtain signals through the path (common CAN line 2 + vehicle CAN line + common CAN line 4) for backup. Figure 7The diagram illustrates a scenario where signal transmission fails in inter-board communication 1, the interaction between the upper steering master MCU and the upper steering slave MCU, such as a failure of the power assist request torque control command signal. In traditional steer-by-wire systems, the slave MCU of the upper steering system cannot obtain this signal, leading to insufficient power assist output. This can result in understeering at high speeds, potentially causing loss of vehicle control and posing a significant safety hazard. To ensure normal software functionality, this embodiment employs a common CAN communication method for redundancy. When signal transmission fails in inter-board communication 1, such as... Figure 6 As shown, the steer-by-wire MCU can still obtain signals through path 1 (common CAN line 1 + vehicle CAN line + common CAN line 2), enabling the steer-by-wire system to still provide full power assist output and alert the driver to help the vehicle pull over to the side of the road, avoiding the risk of losing vehicle control, thus greatly improving system availability.

[0064] like Figure 8 The diagram shows the signal transmission flowchart when the inter-board communication 1 between the upper steering master MCU and the upper steering slave MCU fails, including the following steps:

[0065] Step 1: Determine whether the signal received from the edge MCU during the upward turn originates from inter-board communication 1. If yes, proceed to step 2; otherwise, end the process.

[0066] Step 2: Determine whether the signal received from the edge MCU is valid. If it is, select inter-board communication 1 as the signal output channel and end; otherwise, proceed to step 3.

[0067] Step 3: Determine whether the signal transmitted by common CAN line 2 is valid. If it is, select common CAN line 2 as the signal output channel, obtain the signal from the transmission path of common CAN line 1 + vehicle CAN line + common CAN line 2, and end. If not, output an invalid signal value and end.

[0068] The signal transmission method and system of the steer-by-wire system of the present invention enhance the usability of the steer-by-wire system software functions, realize precise control of the vehicle's ADAS functions, and provide customers with a better intelligent driving experience. Simultaneously, by prioritizing and fusing multiple input signals for output, the software architecture design reduces the interfaces for interaction between software elements, making the data flow clearer. Furthermore, the implementation method of hardware dual-channel and software safety algorithms ensures signal safety redundancy, greatly improving the safety of the entire steer-by-wire system at the signal transmission level.

[0069] The present invention has been described in detail above through specific embodiments. These embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the above-described implementation methods. Equivalent substitutions and improvements made by those skilled in the art without departing from the principles of the present invention should be considered within the scope of the technology protected by the present invention.

Claims

1. A signal transmission system for improving the usability of a steer-by-wire system, the steer-by-wire system comprising an upper steering system, a vehicle signal processing system, and a lower steering system, wherein the upper steering system is configured with an upper steering master MCU and an upper steering slave MCU, and the lower steering system is configured with a lower steering master MCU and a lower steering slave MCU, characterized in that, The upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU and the vehicle signal processing system interact with the vehicle CAN line through different common CAN lines. The common CAN line is used to transmit the interaction signals between the vehicle and the steer-by-wire system. The upper steering master MCU and the upper steering slave MCU, and the lower steering master MCU and the lower steering slave MCU interact through inter-board communication, which is used to transmit the interaction signals between the master MCU and the slave MCU. The upper steering master MCU and the lower steering master MCU, as well as the upper steering slave MCU and the lower steering slave MCU, communicate via private CAN lines. The private CAN lines are used to transmit the interaction signals between the drive-by-wire upper steering system and the lower steering system.

2. The signal transmission system for improving the availability of a steer-by-wire system according to claim 1, characterized in that, The upper steering master MCU and the lower steering master MCU form a master-master channel, and the upper steering slave MCU and the lower steering slave MCU form a slave-slave channel. The system prioritizes the upper and lower steering control through the master-master channel, and the slave channel provides backup for the upper and lower steering signals. A UART1 channel is set between the upper steering master MCU and the upper steering slave MCU, and a UART2 channel is set between the lower steering master MCU and the lower steering slave MCU. The system performs master-side and slave-side signal backup through the UART1 channel and the UART2 channel respectively.

3. A signal transmission method using the signal transmission system for improving the usability of a steer-by-wire system as described in claim 1, characterized in that, When the signal in the common CAN line of the upper steering system and / or lower steering system fails, the signal is obtained by inter-board communication or common CAN communication. When the private CAN line between the upper steering master MCU and the lower steering master MCU or the private CAN line between the upper steering slave MCU and the lower steering slave MCU fails to transmit signals, the signal is obtained by using either private CAN communication or public CAN communication. When both the private CAN line between the upper steering master MCU and the lower steering master MCU and the private CAN line between the upper steering slave MCU and the lower steering slave MCU fail to transmit signals simultaneously, the common CAN communication method is used to obtain the signal. When signal transmission fails during inter-board communication between the upper steering master MCU and the upper steering slave MCU and / or between the lower steering master MCU and the lower steering slave MCU, the common CAN communication method is used to obtain the signal.

4. The signal transmission method for improving the availability of a steer-by-wire system according to claim 3, characterized in that, A signal failure in the common CAN line of the upper steering system and / or lower steering system includes a signal transmission failure in any one, two, or three common CAN lines that interact with the vehicle CAN bus of the upper steering master MCU, upper steering slave MCU, lower steering master MCU, lower steering slave MCU, and the vehicle CAN bus.

5. The signal transmission method for improving the availability of a steer-by-wire system according to claim 4, characterized in that, When a signal fails in the common CAN line of the upper steering system and / or lower steering system, the required corresponding signal is obtained according to the path of inter-board communication + common CAN line or the path of common CAN line + private CAN line.

6. The signal transmission method for improving the availability of a steer-by-wire system according to claim 3, characterized in that, When a signal transmission failure occurs on the private CAN line between the upper steering master MCU and the lower steering master MCU, or on the private CAN line between the upper steering slave MCU and the lower steering slave MCU, the required corresponding signal is obtained according to the path of the private CAN line + inter-board communication or the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

7. The signal transmission method for improving the availability of a steer-by-wire system according to claim 3, characterized in that, When both the private CAN lines between the upper steering master MCU and the lower steering master MCU and the private CAN lines between the upper steering slave MCU and the lower steering slave MCU fail to transmit signals simultaneously, the required signals are obtained by using the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

8. The signal transmission method for improving the availability of a steer-by-wire system according to claim 3, characterized in that, When the inter-board communication between the upper steering master MCU and the upper steering slave MCU fails to transmit signals, the upper steering master MCU and the upper steering slave MCU obtain signals through the path composed of the two common CAN lines for interaction between the upper steering system and the vehicle and the vehicle CAN line. When the inter-board communication between the lower steering master MCU and the lower steering slave MCU fails to transmit signals, the lower steering master MCU and the lower steering slave MCU obtain signals through the path composed of the two common CAN lines that the lower steering system interacts with the vehicle and the vehicle CAN line.

9. The signal transmission method for improving the availability of a steer-by-wire system according to claim 5, characterized in that, The path of inter-board communication + public CAN line has a higher priority than the path of public CAN line + private CAN line.

10. The signal transmission method for improving the availability of a steer-by-wire system according to claim 6, characterized in that, The path of private CAN line + inter-board communication has a higher priority than the path composed of the common CAN line of the upper steering system, the vehicle CAN line, and the common CAN line of the lower steering system.

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