A method, controller and vehicle for temporary control of a steer-by-wire system in the absence of cornering calibration

Abstract

The application discloses a kind of temporary control method, controller and vehicle when the corner calibration of steer-by-wire system is missing, comprising the following steps: S1, steer-by-wire system controller enters temporary control mode if effective neutral calibration data is not detected;S2, control steering wheel respectively rotates to left limit position and right limit position to the left and right and records the original value of corresponding steering wheel angle sensor, calculates temporary steering wheel zero;S3, set temporary transmission ratio;S4, read the original value of wheel angle sensor at this time, establish the temporary mapping relationship of steering wheel angle-target wheel angle according to temporary steering wheel zero, temporary transmission ratio and the original value of wheel angle;The application has the advantages of being able to automatically, quickly establish a set of temporary zero reference and steering mapping relationship, restore the basic steering and moving ability of vehicle, support vehicle assembly off-line moving vehicle, temporary operation such as maintenance after delivery, etc.

Description

Technical Field

[0001] This invention relates to the field of steer-by-wire technology, specifically to a temporary control method, controller, and vehicle for a steer-by-wire system when steering angle calibration is missing. Background Technology

[0002] Steer-by-wire systems represent a significant development in modern automotive steering technology. They replace the mechanical connection between the steering wheel and wheels in traditional steering systems with electrical signals. The core working principle is as follows: real-time acquisition of the steering wheel angle input signal, combined with vehicle status information, allows the controller to calculate the target wheel angle, which is then driven by a motor to achieve steering.

[0003] To achieve precise control, the steer-by-wire (SBW) system must accurately know the absolute angular zero position of the steering wheel and wheels (i.e., the center position of the vehicle when traveling in a straight line). In engineering practice, this information is obtained through angle sensors mounted on the steering column and steering actuator. However, due to factors such as sensor installation tolerances and electrical characteristics, there is a fixed deviation between the raw signal output by the sensor and the physical zero position; this deviation is known as the "center calibration data".

[0004] Therefore, after a vehicle rolls off the assembly line or after-sales replacement of steering-related components, a calibration procedure must be performed using specialized diagnostic equipment to write the median data into the controller for the system to function properly. However, if the SBW system lacks valid median data due to lack of calibration, lost or invalid calibration data, the system will be unable to interpret the absolute steering angle, causing the core steering function to completely fail. This not only severely impacts production efficiency (e.g., vehicles cannot be removed from the assembly line in the final assembly workshop) but also poses safety hazards during maintenance and in extreme situations, limiting the reliability and ease of use of the SBW system. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome existing defects and provide a temporary control method for steer-by-wire systems when steering angle calibration is missing. When the system lacks steering wheel-wheel centerline calibration data, it can automatically and quickly establish a temporary zero-position reference and steering mapping relationship, enabling vehicles equipped with steer-by-wire systems to regain basic steering and movement capabilities. This supports temporary operations such as vehicle relocation after final assembly and post-repair operations, improving the reliability and ease of use of the steer-by-wire system. At the end of vehicle assembly or in the repair shop, safe short-distance vehicle movement can be achieved without waiting for or prioritizing calibration work, simplifying logistics scheduling and improving overall operational efficiency. Establishing the temporary zero-position reference and steering mapping relationship does not require left or right rotation of the vehicle's wheels or steering rack, and is not constrained by the external environment, expanding its application range. The control logic is rigorous, ensuring control safety; implementation is flexible and highly compatible; and it effectively solves the problems in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a temporary control method for a steer-by-wire system when steering angle calibration is missing, comprising the following steps:

[0007] Step S1, System Status Detection and Mode Trigger: When the vehicle is powered on, the steer-by-wire system controller starts; the steer-by-wire system controller checks whether there is valid steering wheel and wheel centering calibration data stored internally; if no valid centering calibration data is detected, it enters temporary control mode;

[0008] Step S2, Steering Wheel Learning and Temporary Steering Wheel Zero Position Determination: After entering the temporary control mode, control the steering wheel to rotate left and right to the left and right extreme positions respectively, and record the corresponding original values ​​of the steering wheel angle sensor. and The temporary steering wheel zero position is calculated based on the raw values ​​of the steering wheel angle sensor corresponding to the two extreme positions. ;

[0009] Step S3, Set the temporary gear ratio: Define the total mechanical travel of the steering wheel as... The total design turning angle of the wheel from the left limit to the right limit is defined as... The temporary gear ratio between the steering wheel and the wheels is Furthermore, the set temporary transmission ratio satisfies the requirement that at most half of the steering wheel's travel can establish a one-to-one correspondence with the entire turning angle travel of the wheel;

[0010] Step S4: Establish a temporary mapping relationship: Keep the wheel position unchanged and read the original value of the wheel steering angle sensor at this time. According to the temporary steering wheel zero position Temporary transmission ratio and the original value of the wheel angle Establish a temporary mapping relationship between the steering wheel angle and the target wheel angle;

[0011] Step S5, Steering Control: Control the vehicle steering according to the established temporary mapping relationship.

[0012] Furthermore, in step S2, the formula for calculating the temporary steering wheel zero position is: .

[0013] Furthermore, in step S3, the temporary transmission ratio value The following relationship must be satisfied: This ensures that the steering wheel can control the entire wheel turning angle travel even when the initial position of the wheels is unknown.

[0014] Furthermore, in step S3, a safety factor is introduced to allow for a certain safety margin in preventing control command saturation due to sensor noise or calculation errors. ,and Less than 1; safety factor Substituting the temporary transmission ratio, we get the formula: .

[0015] Furthermore, in step S3, the temporary transmission ratio between the steering wheel and the wheels is set as follows: ,and It is 0.9.

[0016] Furthermore, in step S4, the raw value of the wheel steering angle sensor is read. It was later defined as the temporary wheel zero position. In the steering control step S5, for any real-time steering wheel sensor reading... The steer-by-wire system controller calculates the angle increment relative to the temporary zero position of the steering wheel. Then calculate the target wheel angle. ,and .

[0017] Furthermore, in step S2, the method of controlling the steering wheel rotation includes: prompting the driver to rotate the steering wheel, or having the steering wheel module's drive motor automatically rotate the steering wheel.

[0018] Furthermore, the temporary zero position Temporary transmission ratio The data is only valid within the current vehicle ignition cycle; if new median calibration data is obtained through an external calibration program within the current ignition cycle, the new median calibration data will be used to replace the temporary zero position. and temporary transmission ratio Perform steering control.

[0019] To achieve the above objectives, the present invention also provides the following technical solution: a steer-by-wire system controller, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the temporary control method described above.

[0020] To achieve the above objectives, the present invention also provides the following technical solution: a vehicle, including a vehicle body equipped with the above-mentioned steer-by-wire system controller, used to realize basic steering movement capability when moving the vehicle or relocating it.

[0021] Compared with the prior art, the present invention has the following significant advantages:

[0022] 1. Functional degradation recovery is achieved, improving system robustness: Without relying on any pre-calibrated data, a temporary zero-position reference and steering mapping relationship can be automatically and quickly established, enabling the steer-by-wire system to have the ability to "start from zero". This allows vehicles equipped with the steer-by-wire system to restore basic steering and movement capabilities, thereby supporting temporary operations such as vehicle relocation after final assembly and post-maintenance removal from the warehouse, greatly enhancing the availability and safety of the system in abnormal conditions.

[0023] 2. Not constrained by external environment: When establishing a temporary zero-position reference and steering mapping relationship, there is no need to rotate the vehicle's wheels or steering rack left or right, and it is not constrained by the vehicle's external environment, thus expanding its scope of use.

[0024] 3. Optimize production and maintenance processes and improve efficiency: At the end of vehicle assembly or in the maintenance workshop, calibration work can be carried out safely and short distances without waiting or prioritizing, which simplifies logistics scheduling and improves overall operational efficiency.

[0025] 4. Rigorous logic ensures control safety: The unique design of "temporary transmission ratio limit" realizes the control of the entire wheel turning angle by half mapping of the steering wheel travel, which fundamentally ensures the uniqueness and controllability of the steering mapping relationship even under the most unfavorable initial wheel position, and avoids control logic conflicts.

[0026] 5. Flexible implementation and strong compatibility: The temporary control method supports both driver cooperation and automatic system execution, adapting to different scenarios; at the same time, the clear temporary data lifecycle management mechanism ensures seamless integration with the standard calibration process and eliminates the risk of data conflict. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the hardware architecture of the steer-by-wire system for the temporary control method of the present invention;

[0028] Figure 2 This is an overall flowchart of the temporary control method of the present invention;

[0029] Figure 3 This is a schematic diagram illustrating the normal mapping relationship between the steering wheel and the wheel rotation angle.

[0030] Figure 4 This is a schematic diagram illustrating the temporary mapping relationship between the steering wheel and wheel rotation angles of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Please see Figure 1-4 This invention provides a technical solution: a temporary control method for a steer-by-wire system when steering angle calibration is missing, comprising the following steps:

[0034] Step S1, System Status Detection and Mode Trigger: When the vehicle is powered on, the steer-by-wire system controller starts. The steer-by-wire system controller first reads the pre-stored center calibration data of the steering column and steering actuator in its internal non-volatile memory (such as EEPROM) and performs validity verification (e.g., checking whether the data is within a preset reasonable range and whether the checksum is correct). If the verification passes, the steer-by-wire system controller uses the calibration data for normal high-precision steering control. If the verification fails or the data is empty, the steer-by-wire system controller determines that there is "no valid calibration data" and automatically triggers entry into "temporary control mode". At the same time, a prompt message, such as "Steering system is initializing", can be displayed to the driver through the instrument panel.

[0035] Step S2, Steering Wheel Learning and Temporary Steering Wheel Zero Position Determination: After entering the temporary control mode, control the steering wheel to rotate left and right to the left and right extreme positions respectively, and record the corresponding original values ​​of the steering wheel angle sensor. and The temporary steering wheel zero position is calculated based on the raw values ​​of the steering wheel angle sensor corresponding to the two extreme positions. The formula for calculating the temporary zero position of the steering wheel is:

[0036] (1)

[0037] Temporary steering wheel zero position Defined as the geometric center of the steering wheel's mechanical travel, this position will be regarded as the steering wheel reference position for the vehicle's "straight-line driving" during this ignition cycle;

[0038] The operation of rotating the steering wheel to its left and right extreme positions can be achieved in the following two ways:

[0039] Driver operation mode: The steer-by-wire system guides the driver to slowly and continuously turn the steering wheel to the left and right respectively to the mechanical limit position where it can no longer be turned, and hold each position for a short time (e.g., 1 second); during this period, the steer-by-wire system records the raw output value of the steering wheel angle sensor in real time.

[0040] Automatic execution mode: The steer-by-wire system controls the drive motor in the steering wheel (i.e., the motor that provides road feel feedback) to automatically drive the steering wheel to the left and right mechanical limit positions respectively.

[0041] Step S3, Set the temporary gear ratio: Define the total mechanical travel of the steering wheel as... ( It is a constant, and The total design turning angle of the wheel from the left limit to the right limit is defined as follows: ( It is a known fixed value determined by the geometric parameters of the vehicle's steering mechanism, that is, the theoretical turning angle of the wheel from the left limit to the right limit. (As a constant); to ensure unambiguous control of the steering wheel's entire wheel rotation travel (from one rotation limit to another) even with unknown initial wheel positions (the wheel may be at its left limit, right limit, or any intermediate position), an "overshoot" mapping relationship must be established between the steering wheel's rotation range and the wheel's rotation range; the temporary transmission ratio between the steering wheel and the wheel is set to... The temporary transmission ratio satisfies the following relationship:

[0042] (2)

[0043] The purpose of this setting is that at most half of the steering wheel's travel can establish a one-to-one correspondence with the entire turning angle travel of the wheel; that is, the steering wheel only needs to turn half (or less) of its total mechanical travel to instruct the wheel to complete the entire turning angle travel.

[0044] To prevent control command saturation due to sensor noise or calculation errors, a safety margin is introduced to provide a certain safety factor. ,and Less than 1; safety factor Substituting into relation (2), we get:

[0045] (3)

[0046] In this embodiment, the safety factor The value is 0.9, and the temporary gear ratio between the steering wheel and the wheels is set as follows:

[0047] (4)

[0048] Assuming total steering wheel travel The total wheel travel is 1440° (4 revolutions). If the angle is 40°, then the standard transmission ratio is... The ratio is 36:1, at which point the angle relationship between the steering wheel and the wheels is as follows: Figure 3 As shown; and the temporary transmission ratio set in this invention is: This means that the wheel can turn from one limit to the other in less than two turns (648°), ensuring that the steering wheel can control the entire wheel turning angle without ambiguity even when the initial position of the wheel is unknown.

[0049] Step S4: Set temporary wheel zero position: After the steering wheel travel learning is completed, keep the wheel position unchanged and read the original value of the wheel angle sensor at this time. And define it as temporary wheel zero position. This means that, under the current control logic, the steer-by-wire system considers the actual position of the wheels to be the "zero point".

[0050] Step S5: Establish a temporary mapping relationship: Based on the temporary parameters determined above, establish a control mapping from the steering wheel angle input to the wheel angle output; for any given time, the steering wheel angle sensor reading is... The steer-by-wire system controller calculates the angle increment relative to the temporary zero position of the steering wheel. And the increase in steering wheel angle The calculation formula is as follows:

[0051] (5)

[0052] According to the temporary steering wheel zero position Temporary transmission ratio Temporary wheel zero position and steering wheel angle increment Establish a temporary mapping relationship between the steering wheel angle and the target wheel angle, and then calculate the target wheel angle. Target wheel turning angle The calculation formula is as follows:

[0053] (6)

[0054] Step S5, Steering Control: The vehicle steering is controlled based on the established temporary mapping relationship; that is, the steer-by-wire system controller calculates the target wheel angle. The signal is sent to the steering actuator motor (such as a rack-and-pinion motor) to drive the wheels to steer; because The value is relatively small (the transmission is relatively "direct"), and the mapping relationship is established based on a temporary zero position. Therefore, the vehicle can make a sensitive steering response to the rotation of the steering wheel and realize basic functions of moving the vehicle and relocating it.

[0055] At this point, the angle relationship between the steering wheel and the wheels is as follows: Figure 4 As shown; if the current wheel is at the left limit corresponding to the zero position of the steering wheel, The value of corresponds to the right limit of the wheel near the right limit of the steering wheel, such as... Figure 4 As shown in a; if the current wheel is at its right limit, this corresponds to the zero position of the steering wheel. The value of corresponds to the left limit of the wheel when it is near the left limit of the steering wheel, such as... Figure 4 As shown in b; this method establishes a one-to-one correspondence between the wheel and steering wheel angles, thereby supporting the vehicle to achieve all steering angles.

[0056] Step S6, Temporary Data Lifecycle Management: To clarify the "temporary" attribute of this method and ensure compatibility with the formal calibration process, the following management rules are set:

[0057] Single-cycle validity: All temporary data calculated within this ignition cycle ( , , These data are stored only in the controller's volatile memory (such as RAM); when the vehicle is turned off and the next ignition cycle begins, these data will be cleared. If there is still no valid calibration data, steps S1 to S5 must be repeated.

[0058] Priority Management: During the current ignition cycle, if the maintenance personnel successfully execute the standard steering center calibration procedure using diagnostic equipment and obtain a set of compliant, high-precision center calibration data, the steer-by-wire system controller will immediately overwrite or replace the currently used temporary data with the new calibration data. The system will then exit the "temporary control mode" and switch to the "normal control mode" using the new calibration data. The steering ratio will also be restored to the nominal value set by the vehicle, ensuring that the temporary solution does not interfere with the normal maintenance process.

[0059] Example 2

[0060] This invention also provides a steer-by-wire system controller, including a memory (ROM / RAM / EEPROM), a processor (MCU), a signal input interface (for receiving signals from the steering wheel and wheel sensors), and a drive output interface (for controlling the steering wheel motor and the steering actuator motor). The memory stores a computer program, and when the processor executes the program, it implements the steps described in Embodiment 1 above. This steer-by-wire system controller can be integrated into an existing SBW main controller, and the functions of this invention can be realized through software upgrades without increasing hardware costs.

[0061] Example 3

[0062] The present invention also provides a vehicle, the vehicle body of which is equipped with the steer-by-wire system controller described in Embodiment 2 above; the vehicle has the ability to achieve basic steering movement through the temporary control method of the steer-by-wire controller when there is no calibration data for the steering system.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A temporary control method for a steer-by-wire system when steering angle calibration is missing, characterized in that, Includes the following steps: Step S1, System Status Detection and Mode Trigger: When the vehicle is powered on, the steer-by-wire system controller starts; the steer-by-wire system controller checks whether there is valid steering wheel and wheel centering calibration data stored internally; if no valid centering calibration data is detected, it enters temporary control mode; Step S2, Steering Wheel Learning and Temporary Steering Wheel Zero Position Determination: After entering the temporary control mode, control the steering wheel to rotate left and right to the left and right extreme positions respectively, and record the corresponding original values ​​of the steering wheel angle sensor. and The temporary steering wheel zero position is calculated based on the raw values ​​of the steering wheel angle sensor corresponding to the two extreme positions. ; Step S3, Set the temporary gear ratio: Define the total mechanical travel of the steering wheel as... The total design turning angle of the wheel from the left limit to the right limit is defined as... The temporary gear ratio between the steering wheel and the wheels is Furthermore, the set temporary transmission ratio satisfies the requirement that at most half of the steering wheel's travel can establish a one-to-one correspondence with the entire turning angle travel of the wheel; Step S4: Establish a temporary mapping relationship: Keep the wheel position unchanged and read the original value of the wheel steering angle sensor at this time. According to the temporary steering wheel zero position Temporary transmission ratio and the original value of the wheel angle Establish a temporary mapping relationship between the steering wheel angle and the target wheel angle; Step S5, Steering Control: Control the vehicle steering according to the established temporary mapping relationship.

2. The temporary control method for a steer-by-wire system in the absence of steering angle calibration according to claim 1, characterized in that: In step S2, the formula for calculating the temporary steering wheel zero position is: .

3. A temporary control method for a steer-by-wire system in the event of missing steering angle calibration, as described in claim 1, characterized in that: In step S3, the temporary transmission ratio value The following relationship must be satisfied: This ensures that the steering wheel can control the entire wheel turning angle travel even when the initial position of the wheels is unknown.

4. A temporary control method for a steer-by-wire system in the event of missing steering angle calibration, as described in claim 3, characterized in that: In step S3, a safety factor is introduced to allow for a certain safety margin in order to prevent control command saturation due to sensor noise or calculation errors. ,and Less than 1; safety factor Substituting the temporary transmission ratio, we get the formula: .

5. A temporary control method for a steer-by-wire system in the event of missing steering angle calibration, as described in claim 1, characterized in that: In step S4, the raw value of the wheel steering angle sensor is read. It was later defined as the temporary wheel zero position. In the steering control step S5, for any real-time steering wheel sensor reading... The steer-by-wire system controller calculates the angle increment relative to the temporary zero position of the steering wheel. Then calculate the target wheel angle. ,and .

6. A temporary control method for a steer-by-wire system in the event of missing steering angle calibration, as described in claim 1, characterized in that: In step S2, the methods for controlling the steering wheel rotation include: prompting the driver to rotate the steering wheel, or having the steering wheel module's drive motor automatically rotate the steering wheel.

7. A temporary control method for a steer-by-wire system in the event of missing steering angle calibration, as described in claim 1, characterized in that: The temporary zero position Temporary transmission ratio The data is only valid within the current vehicle ignition cycle; if new median calibration data is obtained through an external calibration program within the current ignition cycle, the new median calibration data will be used to replace the temporary zero position. and temporary transmission ratio Perform steering control.

8. A controller for a steer-by-wire system, characterized in that: It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the temporary control method as described in any one of claims 1-7.

9. A vehicle, characterized in that: The vehicle body is equipped with a steer-by-wire system controller as described in claim 8, which is used to realize basic steering movement capabilities when moving the vehicle or relocating it.

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