Steer-by-wire system based on a functional set and a control method thereof

Abstract

The application provides a kind of drive-by-wire steering system based on function concentration and control method thereof, wherein the system includes steering wheel module and steering execution module, the steering wheel module includes at least one first electronic control unit, the first electronic control unit is configured to receive and execute force feedback torque instruction from the steering execution module;The steering execution module includes at least one second electronic control unit, and is configured as the calculation and decision core of the system, for receiving vehicle state signal and operation signal from the steering wheel module, uniformly calculating target steering instruction and the force feedback torque instruction, and arbitrating and determining system working mode;The application fundamentally solves the core bottleneck of internal coordination complexity, reliability challenge and high cost of existing distributed redundant drive-by-wire steering system by concentrating function and decision right in the innovative architecture of steering execution module.

Description

Technical Field

[0001] This invention relates to the field of vehicle steer-by-wire control technology, specifically to a steer-by-wire system and control method based on function centralization. Background Technology

[0002] Steer-by-wire (SBW) systems replace traditional mechanical connections with electrical signals to transmit commands and road feel information between the steering wheel and steering wheels, making it a key technology for intelligent vehicles. A typical SBW system includes a Steering Wheel Actuator (SWA) and a Road Wheel Actuator (RWA). Both need to transmit operating modes and command information through electrical and communication networks to work together correctly to achieve system-level functions. This prevents system malfunctions caused by asynchronous SWA and RWA operating modes, which significantly increases the complexity of the SBW control system.

[0003] To further meet high-level functional safety requirements, existing mainstream solutions adopt a dual-redundancy design in both SWA and RWA. That is, each module consists of two functionally identical subsystems. Each subsystem includes independent sensors, electronic control units (ECUs), and actuators, thus forming a distributed architecture with four ECUs.

[0004] When the system realizes functions such as power-on centering, manual steering, and assisted driving, it requires complex and real-time coordination among the four ECUs. This coordination includes: (1) synchronization of working modes and load balancing between the two ECUs within the SWA; (2) synchronization of working modes and load balancing between the two ECUs within the RWA; and (3) system-level mode and command synchronization between the two major modules, SWA and RWA.

[0005] This architecture results in extremely complex internal system interaction logic, creating multi-level coordination and arbitration requirements within and between modules. Existing technologies typically employ a "master-master" or "master-slave" architecture within each redundant module, using internal bus communication to achieve subsystem state synchronization and arbitration. However, this model, with independent arbitration within SWA and RWA respectively, followed by secondary coordination at the system level, significantly increases the complexity of system design, communication load, and the difficulty of developing, debugging, and verifying control software. Failure of coordination or inconsistency at any level can lead to functional degradation or security risks, becoming a significant bottleneck restricting the reliability improvement and cost optimization of SBW systems. Summary of the Invention

[0006] In existing technologies, the distributed architecture of SBW systems leads to complex inter-controller coordination and high overall system complexity. The additional arbitration logic layer in the fully redundant architecture makes this problem even more pronounced. To address these issues, this invention provides a steer-by-wire system and its control method based on functional centralization. The aim is to simplify system design, reduce coordination complexity, thereby improving reliability, reducing costs, and enhancing scalability through fundamental functional refactoring.

[0007] A steer-by-wire system based on function centralization includes a steering wheel module and a steering execution module. The steering wheel module includes at least one first electronic control unit, which is configured to receive and execute force feedback torque commands from the steering execution module.

[0008] The steering execution module includes at least one second electronic control unit and is configured as the calculation and decision-making core of the system, used to: receive vehicle status signals and operation signals from the steering wheel module, uniformly calculate the target steering command and the force feedback torque command, and arbitrate and determine the system working mode.

[0009] Furthermore, the steering wheel angle sensor installed on the steering wheel module has its signal output terminal directly connected to the signal of the second electronic control unit in the steering execution module; the second electronic control unit is configured to directly acquire the signal of the steering wheel angle sensor.

[0010] Furthermore, the steering execution module includes at least two second electronic control units.

[0011] Furthermore, the steering wheel module includes at least two first electronic control units, wherein the first electronic control units do not have a dedicated communication connection for system operating mode coordination or load balancing arbitration.

[0012] Furthermore, each first electronic control unit in the steering wheel module establishes a direct communication connection with each second electronic control unit in the steering execution module, forming a star-shaped communication network centered on the steering execution module.

[0013] Furthermore, each of the second electronic control units is configured as follows:

[0014] Based on the received status information of all the first and second electronic control units, the system health is independently assessed;

[0015] According to the preset arbitration strategy, one of the second electronic control units is dynamically determined as the main controller of the current system based on the system health status.

[0016] The main controller, as a valid command source, generates the target steering command and the force feedback torque command, and distributes them to all other electronic control units in the system.

[0017] Furthermore, the preset arbitration strategy includes: when the health levels assessed by the two second electronic control units are the same, the current main controller role is maintained; when a role conflict occurs, one of the preset second electronic control units is designated as the main controller.

[0018] Furthermore, the system health assessment is based on the availability status of at least one of the following components: the steering wheel module's sensor, the steering wheel module's feedback motor, the steering actuation module's sensor, and the steering actuation module's steering motor.

[0019] Furthermore, the second electronic control unit communicates with each other via a private communication bus for status synchronization and arbitration.

[0020] A steer-by-wire control method based on function concentration, applied to a steering execution module comprising a steering wheel module with at least one first electronic control unit and at least one second electronic control unit, characterized in that the method includes:

[0021] The steering execution module serves as the calculation and decision-making core of the system, receiving vehicle status signals and operation signals sent by the steering wheel module;

[0022] The steering execution module uniformly calculates the target steering command and the force feedback torque command;

[0023] The steering execution module arbitrates and determines the system operating mode, wherein the first electronic control units are configured to operate independently of each other and do not perform mutual arbitration of operating modes.

[0024] The force feedback torque command is sent to the steering wheel module for execution, and the target steering command is sent to the corresponding actuator.

[0025] The beneficial effects of this invention are as follows: By centralizing functionality and decision-making power in the steering execution module, this invention fundamentally solves the core bottlenecks of existing distributed redundant steer-by-wire systems, such as complex internal coordination, high reliability challenges, and high costs. Its beneficial effects are reflected in its comprehensive advantages, from simplified architecture and improved reliability to reduced costs and future scalability, providing a superior solution for the industrial application of steer-by-wire technology. Specifically:

[0026] 1. System architecture and complexity are fundamentally simplified.

[0027] Eliminating redundant arbitration levels: By centralizing the core computing, decision-making and arbitration functions entirely in the steering execution module (RWA), the complex working mode synchronization and load balancing arbitration requirements between multiple electronic control units within the steering wheel module (SWA) are completely eliminated;

[0028] Simplified system interaction: The complex mesh-like coordination between the four ECUs in the traditional solution is simplified into a centralized coordination centered on the RWA. The SWA unit, acting as an instruction execution and signal feedback unit or simply as an instruction execution unit, communicates directly with the RWA through a star network, greatly reducing the logical complexity and communication load of internal system interactions;

[0029] 2. System reliability is significantly improved.

[0030] The decision-making path is unique and clear: global control decisions and arbitration logic are centralized in RWA, which performs unified monitoring and adjudication based on the global state information of all units, avoiding the multi-level arbitration result conflicts or state inconsistencies that may occur in traditional distributed architectures.

[0031] Enhanced behavioral certainty: The adoption of a dynamic arbitration strategy based on quantified "system health" makes the election of the master controller and the switching logic of the system working mode clear and predictable, thereby improving the stability and safety behavior certainty of the system under fault conditions.

[0032] 3. Overall costs are effectively reduced.

[0033] Hardware cost optimization: The SWA function is greatly simplified, and the requirements for the computing power, software complexity and internal communication interface of its electronic control unit are significantly reduced, which is conducive to adopting a lower-cost hardware solution.

[0034] Improved development and verification efficiency: The overall software complexity of the system is reduced, the coordination logic between controllers is simplified, the workload of development, debugging, testing and verification of control software is significantly reduced, the development cycle is shortened and the R&D cost is reduced;

[0035] Promote module standardization: The simplified SWA makes it easier to achieve standardized and platform-based design, which is convenient for reuse in different models or product lines, further reducing procurement and manufacturing costs;

[0036] 4. Enhanced system scalability and adaptability

[0037] Achieving decoupling between core and input: This architecture achieves loose coupling between the core control logic (located in RWA) and the upper-level driver input device (SWA); in the future, when adapting to different steering wheel shapes (such as rectangular steering wheels, folding steering wheels) or integrating advanced autonomous driving commands, only the simplified SWA needs to be adapted, while the core system architecture and control strategy remain unchanged.

[0038] Flexible support for product matrix: The same core design concept of "centralized functions" can cover a variety of product forms from high-reliability dual-redundant systems to low-cost simplified systems, with low cost of technology evolution and product derivation;

[0039] 5. Optimization of communication and diagnostic efficiency

[0040] Communication topology optimization: Direct star communication centered on RWA avoids bridging and data forwarding delays between the module's internal private bus and the system-level bus, improving the transmission efficiency of instructions and status information;

[0041] Centralized fault diagnosis: The status information and fault diagnosis results of all critical components are aggregated to RWA for global health assessment, which facilitates unified fault management, degradation strategy formulation and logging at the system level. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the physical architecture of a steer-by-wire system according to a preferred embodiment of the present invention;

[0043] Figure 2 This is a logic control block diagram of a preferred embodiment of the present invention;

[0044] Figure 3 This is an exemplary system health assessment and arbitration flowchart (taking RWA_ECU1 as an example).

[0045] Figure 4 This is an exemplary system health assessment and arbitration flowchart (taking RWA_ECU2 as an example).

[0046] Figure 5 This is a schematic diagram comparing the coordination methods of traditional distributed arbitration schemes and the centralized arbitration scheme of this invention;

[0047] Figure 6 This is a comparative diagram of a traditional distributed logic control block diagram and a centralized logic control block diagram of the present invention.

[0048] Figure 7 It is a logic control block diagram in which the steering wheel sensors transmit the corresponding steering wheel information to the steering unit through a separate communication connection. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings. Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The directional terms such as left, center, right, top, and bottom in the embodiments of the present invention are only relative concepts or referenced to the normal use state of the product, and should not be considered restrictive.

[0050] First embodiment: A steer-by-wire system based on function concentration

[0051] This embodiment uses a dual-redundancy architecture as an example to demonstrate the optimal implementation of the present invention in improving system reliability.

[0052] 1. System Architecture and Hardware Connection

[0053] like Figure 1 As shown, the system includes a steering wheel module and a steering execution module:

[0054] The steering wheel module (SWA) specifically includes two first electronic control units, labeled SWA_ECU1 and SWA_ECU2, and is equipped with a steering wheel torque / angle sensor and a redundant feedback motor;

[0055] The steering actuation module (RWA) specifically includes two second electronic control units, labeled RWA_ECU1 and RWA_ECU2, and is equipped with wheel angle sensors and redundant steering motors;

[0056] The key connectivity features are as follows: each of SWA_ECU1 and SWA_ECU2 is directly connected to RWA_ECU1 and RWA_ECU2 via an independent communication channel (such as CAN FD or Ethernet), forming a fully interconnected star communication network centered on RWA; more importantly, there is no dedicated private communication bus between SWA_ECU1 and SWA_ECU2 for functional coordination (such as torque arbitration); while RWA_ECU1 and RWA_ECU2 can perform status synchronization and arbitration interaction via a private CAN bus. This connection method ensures that any RWA_ECU can obtain the status information of all ECUs in the system.

[0057] The first electronic control units do not have a dedicated communication connection for system operating mode coordination or load balancing arbitration, that is, there is no dedicated communication bus for torque arbitration or load balancing coordination.

[0058] 2. Control Logic and Function Division

[0059] like Figure 2As shown, the core of this embodiment lies in the centralized allocation of functions:

[0060] SWA Function Simplification: The functions of SWA_ECU1 and SWA_ECU2 are limited to local execution, mainly including: (a) acquiring sensor signals through torque / angle detection modules (1a, 2a); (b) receiving and executing force feedback torque commands from RWA through motor control modules (1b, 2b); (c) performing fault diagnosis of this ECU through fault information aggregation modules (1c, 2c). No working mode coordination or load balancing arbitration is required between the two SWA_ECUs.

[0061] RWA functions are centralized: RWA_ECU1 and RWA_ECU2 are responsible for global control and decision-making. Each RWA_ECU includes: (a) a signal processing module (3a, 4a) that collects local signals; (b) a force feedback calculation module (3c, 4c) and a steering command calculation module (3d, 4d) that independently and in parallel calculate a unified force feedback torque and target steering command based on all SWA signals, RWA local signals and vehicle status; and (c) a system control arbitration module (3f, 4f) that receives fault information from all ECUs (1c, 2c, 3e, 4e) through the bus and, combined with its own status, evaluates the "system health" from a global perspective.

[0062] In addition, the control and switching of the entire SBW system's operating modes (such as power-on alignment, manual steering, etc.) are also uniformly controlled by the RWA ECU. The SWA ECU does not need to control the corresponding operating modes or coordinate with the RWA ECU.

[0063] 3. Dynamic Arbitration Method

[0064] 3.1 Health Assessment: Each RWA_ECU is mapped to a quantified "health" level according to the availability status ("1" available, "0" unavailable) of key components such as SWA sensor (5a / 5b), SWA motor (6a / 6b), RWA sensor (7a / 7b), and RWA motor (8a / 8b) based on preset rules (see Table 1 for examples). The assessment dimensions and rules can be expanded as needed.

[0065] Table 1

[0066]

[0067] 3.2 Arbitration Process: After power-on, RWA_ECU1 and RWA_ECU2 operate independently following the same arbitration logic, such as... Figure 3 , Figure 4 The strategy shown is as follows:

[0068] Initialize the default RWA_ECU1 as the master controller;

[0069] During operation, each RWA_ECU compares its own health with that of the peer: if the local health is higher, it should become the master; if the local health is lower, it should become the slave; if they are the same, the role is maintained; if there is a role conflict, it is decided according to the preset rules (such as designating RWA_ECU2 as the master).

[0070] The winning RWA_ECU, acting as the sole command source, broadcasts its calculated force and steering commands to all ECUs (including another RWA_ECU and two SWA_ECUs) via the bus, which then drive the corresponding motors to execute them.

[0071] 4. Advantages Comparison

[0072] like Figure 5 As shown, compared with the traditional solution (left side) which requires three layers of complex arbitration within SWA, RWA, and SWA-RWA, the solution of this invention (right side) only requires one layer of centralized arbitration between the two ECUs within RWA to coordinate the entire system; this greatly simplifies the coordination logic, reduces the development difficulty, and improves reliability due to the unique decision path.

[0073] like Figure 6 As shown in the diagram, this illustration illustrates the core difference in functional deployment between the existing solution and the present invention. The existing solution places the force-sensing command calculation function in the SWA ECU, while the present invention migrates this function to the RWA ECU.

[0074] The existing deployment method presents the following problems: a. How should the instructions calculated by the two SWA ECUs be used? Should they be used independently, or should one be selected after arbitration? b. How should the load between the two SWA ECUs be balanced? c. The operating modes of the SWA ECU and RWA ECU must be coordinated; if the SWA is in power-on alignment mode while the RWA is in manual steering mode, it will lead to chaos in the entire system's operating mode. Therefore, this system has three levels of coordination issues: e. The operating modes and load distribution between the two SWA ECUs need to be coordinated; f. The operating modes and load distribution between the two RWA ECUs need to be coordinated; g. The operating modes of SWA and RWA need to remain coordinated.

[0075] This invention integrates the force-sensing command calculation function into the RWA ECU, thereby solving the coordination problem of the above-mentioned terms e and g: after the two RWA ECUs determine the system operating mode, they can calculate the current command of SWA according to the requirements of the mode; since the RWA can obtain the fault information of SWA, the motor load can be reasonably allocated according to the actual status of each SWA ECU.

[0076] Second Implementation Example: Application Description of Simplified Architecture

[0077] While other technical features remain the same as in the first embodiment, the core idea of ​​this embodiment—"force feedback torque calculation and target steering calculation are both concentrated in RWA"—is also applicable to scenarios that are more cost-sensitive or have lower complexity requirements. For example, only one first electronic control unit is set in the steering wheel module (SWA), and the steering execution module (RWA) specifically includes two second electronic control units, labeled RWA_ECU1 and RWA_ECU2. In such a simplified system, RWA_ECU1 and RWA_ECU2 undertake the global control and decision-making tasks, and are responsible for unified calculation and issuing instructions. SWA only needs to perform signal acquisition and instruction execution. At this time, there is no need for any coordination of working modes between SWA and RWA. Only a centralized arbitration is required between the two ECUs within RWA, making the architecture simpler. This proves that the "functional centralization" paradigm provided by this invention is a general design concept that can cover a variety of product forms, from highly reliable redundant systems to economical simplified systems.

[0078] Third Implementation Example: Application Description of Simplified Architecture

[0079] While other technical features remain the same as in the second embodiment, the core idea of ​​this embodiment—"force feedback torque calculation and target steering calculation are both concentrated in RWA"—is also applicable to scenarios that are more cost-sensitive or have lower complexity requirements. For example, only one first electronic control unit is set in the steering wheel module (SWA), and only one second electronic control unit RWA_ECU is set in the steering execution module (RWA). In such a simplified system, RWA_ECU undertakes the global control and decision-making tasks, and is responsible for unified calculation and issuing instructions; SWA only needs to perform signal acquisition and instruction execution. At this time, there is no need for any coordination of working modes between SWA and RWA, and the architecture is simpler. This proves that the "functional centralization" paradigm provided by this invention is a general design concept that can cover a variety of product forms from highly reliable redundant systems to economical simplified systems.

[0080] Fourth Implementation Example: Explanation of Adaptation to Different Physical Architectures

[0081] While other technical features remain the same as in the first embodiment, the core idea of ​​this embodiment—"both force feedback torque calculation and target steering calculation are concentrated in RWA"—is also applicable to application scenarios where the upturn angle signal is directly connected to the downturn; for example, Figure 7As shown, the signal lines of the SWA sensors (5a / 5b) installed on the steering wheel module (SWA) are directly connected to RWA ECU1 / 2. RWA ECU1 / 2 acquires sensor signals through its internal torque / angle detection module without requiring processing by the SWA ECU, thus avoiding the impact of SWA ECU malfunctions and improving signal safety. In this system architecture, RWA simultaneously acquires angle signals from both SWA and RWA, using these signals to calculate and issue commands. SWA only needs to perform signal acquisition and command execution; regardless of whether the SWA ECU is redundant, the SWA system requires no inter-controller arbitration. This demonstrates that the "functional centralization" paradigm provided by this invention is a universal design concept that can adapt to various design target physical architectures.

[0082] Fifth embodiment: A steer-by-wire control method based on function concentration

[0083] The method, applied to a steering actuator module comprising at least one first electronic control unit and at least two second electronic control units, includes:

[0084] The steering execution module serves as the sole calculation and decision-making core of the system, receiving vehicle status signals and operation signals sent by the steering wheel module.

[0085] The steering execution module uniformly calculates the target steering command and the force feedback torque command;

[0086] The steering execution module arbitrates and determines the system operating mode, wherein the first electronic control units are configured to operate independently of each other and do not perform mutual arbitration of operating modes.

[0087] The force feedback torque command is sent to the steering wheel module for execution, and the target steering command is sent to the corresponding actuator;

[0088] The arbitration and determination of the system's operating mode includes:

[0089] Each second electronic control unit independently assesses the system health based on the status information of all first and second electronic control units;

[0090] Each second electronic control unit (ECU) compares its assessed system health level according to a preset arbitration strategy and dynamically elects one ECU as the system master controller. The preset arbitration strategy includes maintaining the current master controller role when two ECUs have the same assessed health level, and designating one of the preset ECUs as the master controller when a role conflict occurs.

[0091] The elected master controller uniformly generates and distributes the target steering command and the force feedback torque command.

[0092] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A steer-by-wire system based on centralized functions, comprising a steering wheel module and a steering actuation module, characterized in that: The steering wheel module includes at least one first electronic control unit, which is configured to receive and execute force feedback torque commands from the steering actuation module. The steering execution module includes at least two second electronic control units and is configured as the calculation and decision-making core of the system, used to: receive vehicle status signals and operation signals from the steering wheel module, uniformly calculate the target steering command and the force feedback torque command, and arbitrate and determine the system working mode; Each first electronic control unit in the steering wheel module establishes a direct communication connection with each second electronic control unit in the steering execution module, forming a star-shaped communication network centered on the steering execution module; each second electronic control unit is configured as follows: Based on the received status information of all the first and second electronic control units, the system health is independently assessed; According to the preset arbitration strategy, one of the second electronic control units is dynamically determined as the main controller of the current system based on the system health status. The main controller, as a valid command source, generates the target steering command and the force feedback torque command, and distributes them to all other electronic control units in the system.

2. The steer-by-wire system based on function concentration according to claim 1, characterized in that: The steering wheel angle sensor installed on the steering wheel module has its signal output terminal directly connected to the signal of the second electronic control unit in the steering actuation module; the second electronic control unit is configured to directly acquire the signal of the steering wheel angle sensor.

3. The steer-by-wire system based on function concentration according to claim 1, characterized in that: The steering wheel module includes at least two first electronic control units, wherein the first electronic control units do not have a dedicated communication connection for system operating mode coordination or load balancing arbitration.

4. The steer-by-wire system based on function concentration according to claim 1, characterized in that: The preset arbitration strategy includes: when the health levels assessed by the two second electronic control units are the same, the current main controller role is maintained; when a role conflict occurs, one of the preset second electronic control units is designated as the main controller.

5. The steer-by-wire system based on function concentration according to claim 1 or 4, characterized in that: The assessment of the system health is based on the availability status of at least one of the following components: the steering wheel module's sensor, the steering wheel module's feedback motor, the steering actuator module's sensor, and the steering actuator module's steering motor.

6. The steer-by-wire system based on function concentration according to claim 1, characterized in that: The second electronic control unit communicates with each other via a private communication bus for status synchronization and arbitration.

7. A steer-by-wire control method based on function concentration, applied to the steer-by-wire system based on function concentration as described in claim 1, characterized in that, The method includes: The steering execution module serves as the calculation and decision-making core of the system, receiving vehicle status signals and operation signals sent by the steering wheel module; The steering execution module uniformly calculates the target steering command and the force feedback torque command; The steering execution module arbitrates and determines the system operating mode, wherein the first electronic control units are configured to operate independently of each other and do not perform mutual arbitration of operating modes. The force feedback torque command is sent to the steering wheel module for execution, and the target steering command is sent to the corresponding actuator.

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