A method for calibrating the steering wheel angle and wheel angle of steer-by-wire

Abstract

This invention belongs to the technical field of automotive steering systems and relates to a method for calibrating the steering wheel angle and wheel angle of steer-by-wire. By returning the steering wheel and wheels to center after detection and judgment by the force sensor-execution motor system after vehicle ignition and before starting, this invention reduces the need for physical locking of the steering wheel and the steering system. Each ignition cycle recalibrates the system's central and corresponding system calibrations. Simultaneously, it provides excellent power-on correction for errors generated during sleep, errors caused by external forces, and errors caused by human intervention, greatly improving the system's safety factor and functional safety capabilities.

Description

Technical Field

[0001] This invention belongs to the technical field of automotive steering systems and relates to a method for calibrating the steering wheel angle and wheel angle of steer-by-wire. Background Technology

[0002] With the development of automotive steering systems, steer-by-wire systems have gradually gained attention as an advanced technology in the industry. In steer-by-wire systems, the mechanical link between the steering wheel and the steering wheels is eliminated, and there is no mechanical steering column, which improves the vehicle's collision safety. The steering wheel angle and steering torque can be designed independently, which improves the utilization of vehicle space and provides a supporting environment for subsequent high-level intelligent driving.

[0003] However, existing steer-by-wire systems lack the function of calibrating the steering wheel angle and wheel angle when the vehicle is in sleep mode. After the system is powered on, a deviation between the steering wheel angle and the wheel angle is likely to occur, causing the steering system to fail to accurately execute the expected action, resulting in steering failure. Secondly, existing steer-by-wire systems cannot lock the steering wheel at any angle without adding other auxiliary mechanical parts. This problem means that after the vehicle is in sleep mode, the steering wheel can rotate arbitrarily within the effective range, and the current position is only confirmed by the sensor after the vehicle is powered on, at which point the angle difference between the steering wheel and the wheel has already occurred.

[0004] Therefore, there is a need to provide a method for calibrating the steering wheel angle and wheel angle using sensor information during the startup process of an in-vehicle system, so as to facilitate the accuracy of subsequent manual operation and intelligent driving and solve the above-mentioned technical problems. Summary of the Invention

[0005] The technical solution adopted by this invention to solve the technical problem is: a method for calibrating the steering wheel angle and wheel angle of steer-by-wire, comprising the following steps:

[0006] Step 1: After the vehicle is started, the centering function is activated, and the specific triggering is subject to the top-level logic control.

[0007] Step 2: Self-check of the position and midpoint error of each force sensor-execution motor system. When a drive function signal sent by the top-level logic is received, the deviation between the position and midpoint value of each force sensor-execution motor system is determined.

[0008] Step 3: Determine if the median error is within the sensor dead zone. If the median error is within the sensor dead zone, proceed to Step 4; if the median error is not within the sensor dead zone, proceed to Step 6. When the deviation parameter is less than the sensor dead zone, set the active centering function completion flag to "1" and upload it to the top-level logic. When the top-level logic sends a shutdown command, the active centering function ends and its algorithm stops operating. If the deviation parameter is greater than the sensor dead zone, the active centering function is activated.

[0009] Step 4: Activate the centering and automatic return-to-center function;

[0010] Step 5: The steering wheel force sensor motor and wheel actuator motor actively return to the center position, causing the steering wheel and wheels to return to the neutral position.

[0011] Step Six: Determine the median error value. If the median error value is within the sensor dead zone, proceed to Step Seven; if the median error value is not within the sensor dead zone, proceed to Step Four.

[0012] Step 7: Report the completion of the centralization function;

[0013] Step 8: Disable signal reception for centering function;

[0014] Step 9: Disable the centering function.

[0015] Preferably, in step five, when the force-sensing motor is actively returning to its original position and a jamming condition is detected, the following steps are performed:

[0016] Step S1: The return-to-center endpoint of the force sensor motor is changed to the current position of the actuator motor, and the wheel actuator motor no longer performs any action; the return-to-center completion judgment condition is based on the steering wheel completing the return-to-center until the position of the actuator motor system is aligned.

[0017] Step S2: Calculate the steering wheel centering error;

[0018] Step S3: The steering wheel executes an active return-to-center strategy;

[0019] Step S4: Steering wheel center position error judgment. When the steering wheel center position error is less than the sensor dead zone interval, proceed to step S5; when the steering wheel center position error is greater than the sensor dead zone interval, proceed to step S1.

[0020] Step S5: Report the completion of the centering function;

[0021] Step S6: Disable centering function to receive signals;

[0022] Step S7: Disable the centering function.

[0023] Preferably, the method operates between the start of the vehicle ignition cycle and the standby command; this ensures the safety of the driver's operation of the vehicle when the vehicle self-check is completed and enters the standby state, and prevents the driver's operation from conflicting with the return-to-center operation, thus avoiding unnecessary contradictions and safety accidents.

[0024] Preferably, during the operation of the method, the vehicle safety function module is not unlocked and does not lose control; ensuring that the vehicle will not start or move forward due to the return-to-center operation during the return-to-center period.

[0025] The beneficial effects of this invention are:

[0026] This invention can reduce the physical locking of the steering wheel and the physical locking of the steering system. The system will recalibrate the intermediate and corresponding system calibrations in each ignition cycle. At the same time, it can play a good power-on correction function for errors generated during sleep, errors caused by external forces, and errors caused by human intervention, which greatly improves the system safety factor and functional safety capability. Attached Figure Description

[0027] Figure 1 This is a functional architecture diagram of an active return-to-center method for calibrating the steering wheel angle and wheel angle in a steer-by-wire system.

[0028] Figure 2 This is the logic block diagram for the active centering and alignment function;

[0029] Figure 3 This is the logic block diagram of the active centering function in the stuck working condition. Detailed Implementation

[0030] The related technologies of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] refer to Figures 1-3 A method for calibrating the steering wheel angle and wheel angle of steer-by-wire, comprising:

[0032] Step 1: After the vehicle is started, the centering function is activated, and the specific triggering is subject to the top-level logic control.

[0033] Step 2: Self-check of the position and midpoint error of each force sensor-execution motor system. When a drive function signal sent by the top-level logic is received, the deviation between the position and midpoint value of each force sensor-execution motor system is determined.

[0034] Step 3: Determine if the median error is within the sensor dead zone. If the median error is within the sensor dead zone, proceed to Step 4; if the median error is not within the sensor dead zone, proceed to Step 6. When the deviation parameter is less than the sensor dead zone, set the active centering function completion flag to "1" and upload it to the top-level logic. When the top-level logic sends a shutdown command, the active centering function ends and its algorithm stops operating. If the deviation parameter is greater than the sensor dead zone, the active centering function is activated.

[0035] Step 4: Activate the centering and automatic return-to-center function;

[0036] Step 5: The steering wheel force sensor motor and wheel actuator motor actively return to the center position, causing the steering wheel and wheels to return to the neutral position.

[0037] Step Six: Determine the median error value. If the median error value is within the sensor dead zone, proceed to Step Seven; if the median error value is not within the sensor dead zone, proceed to Step Four.

[0038] Step 7: Report the completion of the centralization function;

[0039] Step 8: Disable signal reception for centering function;

[0040] Step 9: Disable the centering function.

[0041] Furthermore, in step five, when the force-sensing motor is actively returning to its original position and a jamming condition is detected, the following steps are performed:

[0042] Step S1: The return-to-center endpoint of the force sensor motor is changed to the current position of the actuator motor, and the wheel actuator motor no longer performs any action; the return-to-center completion judgment condition is based on the steering wheel completing the return-to-center until the position of the actuator motor system is aligned.

[0043] Step S2: Calculate the steering wheel centering error;

[0044] Step S3: The steering wheel executes an active return-to-center strategy;

[0045] Step S4: Steering wheel center position error judgment. When the steering wheel center position error is less than the sensor dead zone interval, proceed to step S5; when the steering wheel center position error is greater than the sensor dead zone interval, proceed to step S1.

[0046] Step S5: Report the completion of the centering function;

[0047] Step S6: Disable centering function to receive signals;

[0048] Step S7: Disable the centering function.

[0049] Furthermore, the method operates between the start of the vehicle ignition cycle and the standby command, ensuring the safety of the driver's operation when the vehicle self-check is completed and enters the standby state, and preventing conflicts between the driver's operation and the return-to-center operation, thus avoiding unnecessary contradictions and safety accidents.

[0050] Furthermore, during the operation of the method, the vehicle safety function module is not unlocked and does not disengage from control; ensuring that the vehicle will not start or move forward due to the return-to-center operation during the return-to-center period.

[0051] Example

[0052] In this embodiment, the active return-to-center scheme for steer-by-wire is mainly modeled and simulated using MATLAB / Simulink software. Then, code is generated according to the embedded code generation specifications and integrated into the underlying layer to complete the embedded application. The scheme is scheduled through a state machine or other top-level functions. Upon completion, the corresponding flag is returned, and then the corresponding logic jump is performed according to the closing instruction of the top-level function.

[0053] Figure 1 This is the architecture diagram for the active centering and alignment function. This function mainly consists of a force-sensor-execute motor system position verification module, a force-sensor motor control module, and an execute motor control module. The force-sensor-execute motor system position verification module includes a module for determining the completion condition of the active centering and alignment function, a module for determining errors in the active centering and alignment function, a module for handling errors in the active centering and alignment function, and a module for executing parameters for the active centering and alignment function. The force-sensor motor system module includes: a motor system control logic module, an active centering and alignment strategy intervention logic module, and a jamming condition judgment logic module. The execute motor system module includes: a motor system control logic module and a follow-up control execution logic module.

[0054] First, this function only exists between the start of the ignition cycle and the standby command. Its specific triggering is controlled by the top-level logic. When a drive function signal is received from the top-level logic, the deviation between the position of the force sensor and the actuator motor system and the center value is first determined. The magnitude of the deviation is then checked to see if it falls within the sensor dead zone. If the deviation is less than the sensor dead zone, the active centering function completion flag is set to "1" and simultaneously uploaded to the top-level logic. When the top-level logic sends a function shutdown command, the active centering function ends, and its algorithm stops calculating. If the deviation is greater than the sensor dead zone, the active centering function intervenes. At this time, the force sensor control system executes the active centering logic function, causing the steering wheel to actively return to the center position. The actuator motor control system executes the follow control execution logic module, causing the wheels to return to the center position.

[0055] This function determines the deviation between the current position and the median value in real time. When the active centering is completed, i.e. the angle position difference is less than the sensor dead zone, it reports that the active centering function is complete. When the top-level logic issues a function shutdown command, the function algorithm stops and the active centering logic function enters normal operation mode.

[0056] like Figure 2 The diagram shows the logic of the active centering function. This function is mainly adjusted by the position verification module of the force sensor-execution motor system. The system state transition determines the conditions for entering this function. When this function is triggered, the conventional power assist system module will no longer operate. The force sensor motor control model and the execution motor control model will only respond to the output command of the position verification module of the force sensor-execution motor system. At the same time, when this function is completed, the position verification module of the force sensor-execution motor system outputs the corresponding completion signal flag, ending all actions of this function. Meanwhile, the conventional power assist system starts to work normally.

[0057] If a jamming condition occurs during operation (the jamming condition is determined by a separate independent module), a special jamming condition handling will be activated. In this case, the force sensor motor control will align the steering wheel with the wheel angle instead of performing center alignment. The actuator motor will then handle the jamming condition and cease all movement. The function is considered complete when the steering wheel has achieved the correct position alignment with the actuator motor system.

[0058] like Figure 3 The diagram shows the logic of the active centering function under stuck conditions. If a stuck condition occurs during the active centering process (determined by an independent module), the system will enter the stuck condition handling mode. That is, the actuator motor control system will maintain the existing position and stop moving, while the force sensor motor control system will switch the centering position from the system's intermediate value to the current position of the actuator motor system. At the same time, other functions will remain unchanged. After the steering wheel position and the wheel position are aligned, the system will proceed with the subsequent execution according to the exit conditions of the normal active centering function logic.

[0059] In this embodiment, the steer-by-wire steering wheel angle and wheel angle calibration method verifies the steering wheel angle and wheel angle during the vehicle's sleep and power-on process. By controlling the active return steering of the steering wheel and wheels, the vehicle's center position return function is completed. On the one hand, this can solve the problem that the steering wheel angle and wheel angle are prone to relative errors when the steer-by-wire system is in the vehicle's sleep state, especially when the steering wheel can be turned freely because it cannot be locked. On the other hand, it can ensure that the vehicle always maintains a straight driving state after power-on, making it easier for the driver to correctly evaluate the current wheel angle. The following issues may arise during the execution of the steer-by-wire method for calibrating the steering wheel angle and wheel angle in this embodiment: First, the steering wheel speed and torque during the active centering process after the vehicle is powered on may affect the driver, and the wheels may not return to the center position due to road conditions or other circumstances. Second, there are accuracy issues after returning to the center position. The accuracy loss during the steering wheel rotation process and the accuracy loss caused by the wheel rotation process need to be processed and eliminated. Third, regarding coordination with other functional modules, during the process from the start to the completion of the active centering function, other safety functional modules should not be unlocked or disengaged from control, which could lead to abnormal vehicle movement.

[0060] In summary, this invention reduces the physical locking of the steering wheel and the steering system. It recalibrates the system's central and corresponding systems every ignition cycle. At the same time, it provides excellent power-on correction for errors generated during sleep, errors caused by external forces, and errors caused by human intervention. This greatly improves the system's safety factor and functional safety capabilities. Therefore, this invention has broad application prospects.

[0061] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for calibrating the steering wheel angle and wheel angle of a steer-by-wire system, characterized in that, Includes the following steps: Step 1: After the vehicle is started, the centering function is activated; Step 2: Force sensing - Self-check of the position and midpoint error of each actuator system; Step 3: Determine whether the median error is within the sensor dead zone. If the median error is within the sensor dead zone, proceed to Step 4; if the median error is not within the sensor dead zone, proceed to Step 6. Step 4: Activate the centering and automatic return-to-center function; Step 5: The steering wheel force sensor motor and wheel actuator motor actively return to the center position, causing the steering wheel and wheels to return to the neutral position. Step Six: Determine the median error value. If the median error value is within the sensor dead zone, proceed to Step Seven; if the median error value is not within the sensor dead zone, proceed to Step Four. Step 7: Report the completion of the centralization function; Step 8: Disable signal reception for centering function; Step 9: Disable the centering function; In step five, when the force-sensing motor is actively returning to its original position and a stuck condition is detected, the following steps are performed: Step S1: The return endpoint of the force sensor motor is changed to the current position of the actuator motor, and the wheel actuator motor no longer performs any action; Step S2: Calculate the steering wheel centering error; Step S3: The steering wheel executes an active return-to-center strategy; Step S4: Steering wheel center position error judgment. When the steering wheel center position error is less than the sensor dead zone interval, proceed to step S5; when the steering wheel center position error is greater than the sensor dead zone interval, proceed to step S1. Step S5: Report the completion of the centering function; Step S6: Disable centering function to receive signals; Step S7: Disconnect the centering function; The method operates from the start of the vehicle ignition cycle to the standby command.

2. The method for calibrating the steering wheel angle and wheel angle of steer-by-wire according to claim 1, characterized in that, During the operation of the method, the vehicle safety function module remains unlocked and under control.

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