A method for calibrating a neutral angle of a steering wheel

Abstract

The application provides a kind of steering wheel middle angle calibration method, comprising the following steps: S1: ECU receives calibration request;S2: whether middle angle calibration condition is satisfied is judged, if satisfied, next step is entered, if not satisfied, this calibration request is ended;S3: steering wheel angle is adjusted;S4: middle angle value is calculated;S5: whether the result of middle angle calculation is reliable is detected, if reliable, next step is entered, if not reliable, calibration failure is reported to ECU and this calibration request is ended;S6: save middle angle data, and end this calibration request, by analyzing the engine speed, vehicle speed signal of whole vehicle, whether middle angle calibration condition is satisfied is judged, by detecting whether the result of middle angle calculation is reliable, simple and efficient, throughout the whole vehicle steering system development process, and angle calibration result is reliable, improve the operation performance of system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power steering systems, and particularly relates to a method for calibrating a center angle of a steering wheel. BACKGROUND

[0002] Modern automobiles are equipped with electric power steering systems (EPS), and when the automobile is steering, the EPS controller judges the steering state of the automobile according to signals such as steering wheel torque and angle, vehicle speed, motor terminal voltage and current, etc., and then sends a control command to drive the EPS motor, so that the motor generates the required assist torque or related compensation torque according to the steering speed and direction of the steering wheel, and the torque is amplified through a worm and gear reduction mechanism and then pushes the wheels to steer through a mechanical steering gear, thereby assisting the driver to steer.

[0003] In the whole life cycle process of vehicle steering system development, assist feel parameter calibration, new vehicle delivery and post-sales, the calibration of the center angle of the steering wheel is an important link, because in use, the center angle of the EPS system deviates from the angle zero point (or the absolute angle zero point of the steering wheel) of the vehicle straight ahead, and if the center angle is not calibrated, a series of problems such as deviation of the steering wheel during driving and abnormal return-to-zero function will occur, thereby affecting the driving experience of the automobile and the driving safety of the driver.

[0004] In the prior art, the angle value is calculated by collecting the torque value through the torque sensor, and then the center value is calculated according to the angle value, but the angle calculation in the prior art has errors, and the calculated center value deviates from the actual center. When the torque signal is abnormal, the angle signal also becomes abnormal because the angle value and the torque value are strongly associated, and the result of the center angle calibration is not reliable.

[0005] Therefore, a new technical solution is needed to solve the above technical problems. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a method for calibrating the center angle of a steering wheel, which is simple in structure, convenient to clamp, and can reduce errors in the test process.

[0007] In order to achieve the above purpose, the present application provides a method for calibrating the center angle of a steering wheel, comprising the following steps:

[0008] S1: The ECU receives a calibration request;

[0009] S2: judging whether the median angle calibration condition is met, if met, entering the next step, if not met, ending the calibration request, wherein the median angle calibration condition is that the automobile is not in the driving process;

[0010] S3: steering wheel angle alignment;

[0011] S4: median angle value calculation, including:

[0012] a: setting the current angle Ang to the maximum angle value Ang_max and the minimum angle value Ang_min;

[0013] b: 10ms timing, after the timing ends, updating the latest angle value obtained by the ECU to Ang,

[0014] c: comparing with the maximum angle value Ang_max and the minimum angle value Ang_min stored last time, if the angle changes, updating Ang_max or Ang_min;

[0015] d: collecting duration judgment, if greater than 100ms, ending the collection, entering the next step, otherwise repeating steps b, c;

[0016] e: judging the collection result, if the difference between Ang_max and Ang_min is greater than 5°, it means that the steering angle changes greatly in the collection time period, so the result is not reliable, if the collection times are greater than 10, the angle calculation result needs to be fed back as unreliable, otherwise repeating steps b, c, d to recollect the angle value for calculation; if the difference is less than 5°, it means that the steering angle changes little in the collection time period, so the angle calculation result is reliable, and the current collected Ang value is the median angle value;

[0017] S5: detecting whether the median angle calculation result is reliable, if reliable, entering the next step, if not reliable, reporting to the ECU that the calibration fails to end the calibration request;

[0018] S6: saving the median angle data and ending the calibration request.

[0019] In further technical solutions, the calibration request in S1 includes calibration requests in the development stage and calibration requests in the production stage.

[0020] In further technical solutions, the calibration request in the development stage includes calibration requests in the case that the vehicle network is not developed and the diagnostic instrument is not developed;

[0021] When the vehicle network is not developed, the ignition operation is performed by turning the key to convey the median angle calibration request to the EPS controller, and the controller performs the function of median angle calibration;

[0022] When the diagnostic instrument is not developed and the vehicle network can work normally, the CAN message is used to convey the neutral angle calibration request to the EPS controller, and the controller executes the neutral angle calibration function.

[0023] In the further technical solution, the calibration request in the mass production stage includes calibration requests in the vehicle production stage and the vehicle after-sales stage.

[0024] In the vehicle production stage, the vehicle sends a UDS diagnostic command to the controller to convey the neutral angle calibration request in the EOL test process, and the controller executes the neutral angle calibration function.

[0025] In the vehicle after-sales stage, if the vehicle replaces the steering control system EPS due to a reason, a UDS diagnostic command can be sent by the after-sales diagnostic instrument to convey the neutral angle calibration request to the controller, and the controller executes the neutral angle calibration function.

[0026] In the further technical solution, the S2 is used to analyze the engine speed and vehicle speed signals of the vehicle to determine whether the angle calibration condition is met.

[0027] Compared with the prior art, the present application has the following technical effects:

[0028] The present application discloses a neutral angle calibration method for a steering wheel, which analyzes the engine speed and vehicle speed signals of the vehicle to determine whether the neutral angle calibration condition is met. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0030] Fig. 1 is a neutral angle calibration flowchart of the present application.

[0031] Fig. 2 is a schematic diagram of the ECU receiving the neutral angle calibration request in different stages.

[0032] Fig. 3is a flow chart for calculating the angle value Ang in the present application. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described below in detail with reference to examples shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for the purpose of explaining the present application, and should not be understood as limiting the present application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0035] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0036] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "on", "above" and "above" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature "under", "below" and "below" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0038] Embodiments

[0039] See Figs. 1-3 As shown in the figure, a steering wheel neutral angle calibration method comprises the following steps:

[0040] S1: the ECU receives a calibration request; S2: determine whether the neutral angle calibration condition is met, if met, go to the next step, if not met, end the calibration request; S3: steering wheel angle alignment; S4: neutral angle value calculation; S5: detect whether the neutral angle calculation result is reliable, if reliable, go to the next step, if not reliable, report to the ECU that the calibration fails and end the calibration request; S6: save the neutral angle data and end the calibration request.

[0041] The present application determines whether the neutral angle calibration condition is met by analyzing the engine speed and vehicle speed signals of the whole vehicle, if the vehicle is in the process of driving, the condition is not met, the neutral calibration request is refused, avoiding the neutral calibration in the process of driving, which will lead to abnormal driving and cause safety accidents. By detecting whether the neutral angle calculation result is reliable, it is simple and efficient, and the angle calibration result is reliable, which improves the operation performance of the system.

[0042] In further embodiments, the calibration request in S1 includes calibration requests in the development stage and calibration requests in the production stage. It should be noted that the steering wheel angle calibration request of the present application exists in the entire vehicle steering system development life cycle. Generally, the whole vehicle neutral angle calibration is performed by sending a UDS diagnostic command to the controller through a specific device, but in the early stage of development, if the network is abnormal or the device is missing, and the neutral angle calibration cannot be performed, it will affect the subsequent whole vehicle assist parameter data calibration work.

[0043] In further embodiments, the calibration request in the development stage includes calibration requests in the case where the whole vehicle network is not developed and the diagnostic instrument is not developed.

[0044] When the whole vehicle network is not developed, the ignition operation is performed by the key to convey the neutral angle calibration request to the EPS controller, and the controller performs the neutral angle calibration function.

[0045] When the diagnostic instrument is not developed and the whole vehicle network can work normally, the neutral angle calibration request can be conveyed to the EPS controller through the CAN message, and the controller performs the neutral angle calibration function.

[0046] In the further technical solution, the calibration request in the mass production stage includes the calibration request in the vehicle production stage and the vehicle after-sales stage.

[0047] In the vehicle production stage, the whole vehicle is tested in the EOL test (off-line detection instrument test of automobile production line), and the neutral angle calibration request is conveyed to the controller by sending the UDS diagnostic command, and the controller performs the neutral angle calibration function.

[0048] In the vehicle after-sales stage, if the vehicle replaces the steering control system EPS due to some reasons, the UDS diagnostic command can be sent by the after-sales diagnostic instrument to convey the neutral angle calibration request to the controller, and the controller performs the neutral angle calibration function.

[0049] In the further technical solution, the engine speed and vehicle speed signals of the whole vehicle are analyzed in S2 to determine whether the angle calibration condition is met.

[0050] In the further technical solution, the neutral angle value calculation in S4 includes the following steps:

[0051] a: Set the current angle Ang to the maximum angle value Ang_max and the minimum angle value Ang_min;

[0052] b: 10ms timing, after the timing is over, the latest angle value obtained by the ECU is updated to Ang,

[0053] c: Compare with the maximum angle value Ang_max and the minimum angle value Ang_min stored last time, if the angle changes, update Ang_max or Ang_min;

[0054] d: Collect the duration to determine, if it is greater than 100ms, end the collection and enter the next step, otherwise repeat step b and step c;

[0055] e: judge the collection result, if the difference between Ang_max and Ang_min is greater than 5°, it indicates that the direction angle changes greatly in the collection time period, and the result is not reliable, if the collection times are greater than 10, the angle calculation result is not reliable, otherwise, repeat steps b, c, d to collect the angle value again for calculation; if the difference is less than 5°, it indicates that the direction angle changes little in the collection time period, and the angle calculation result is reliable, and the current collected Ang value is the median angle value.

[0056] Working principle: after receiving the median angle calibration request of the whole vehicle, the EPS analyzes the engine speed and vehicle speed signals of the whole vehicle to determine whether the condition for median angle calibration is met, if the vehicle is in the driving process, the condition is not met, the median calibration request is refused, and median calibration in the driving process is avoided, which will cause driving abnormality and safety accidents.

[0057] After the environment for median angle calibration meets the requirements, the EPS controller obtains the current steering wheel angle value through the angle sensor, calculates the steering wheel median value, and stores it in the external EEPROM (Electrically Erasable Programmable Read-Only Memory) of the controller.

[0058] The EPS controller obtains the median angle value from the external EEPROM every time it is powered on, in the driving process of the driver, the ECU calculates the real steering wheel angle value by operating the median value and the real-time angle value obtained by the Hall torque angle sensor, and then determines the steering of the vehicle according to the torque of the steering wheel, the vehicle speed, the voltage and current at the motor end, etc., and then sends a control command to drive the EPS motor, so that the motor generates the required assist torque or related compensation torque according to the speed and direction of the steering wheel rotation, and then the torque is amplified through the worm and gear reduction mechanism, and then the mechanical steering gear pushes the wheels to turn, so as to assist the driver in steering operation, and ensure that the driver can not deviate and the return function can normally return to the midpoint in the driving process.

[0059] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0060] Although the embodiments of the present application have been shown and described above, it is to be understood that the above embodiments are merely exemplary, and are not to be understood as a limitation on the scope of the present application, and that changes, modifications, substitutions and variations can be made therein without departing from the spirit and scope of the present application, for example, different combinations of the specific embodiments, different combinations of the various technical features.

Claims

1. A method for calibrating the center angle of a steering wheel, characterized in that: The method comprises the following steps: S1: the ECU receives a calibration request; S2: it is judged whether the median angle calibration condition is met, if yes, the next step is entered, if not, the calibration request is ended, wherein the median angle calibration condition is that the automobile is not in the driving process; S3: the steering wheel angle is adjusted; S4: the median angle value is calculated, comprising: a: the current angle Ang is set as the maximum angle value Ang_max and the minimum angle value Ang_min; b: 10 ms is counted, after the counting is ended, the latest angle value obtained by the ECU is updated to Ang, c: the maximum angle value Ang_max and the minimum angle value Ang_min stored last time are compared, if the angle changes, Ang_max or Ang_min is updated; d: the collection duration is judged, if it is greater than 100 ms, the collection is ended, the next step is entered, otherwise, steps b and c are repeated; e: the collection result is judged, if the difference between Ang_max and Ang_min is greater than 5°, it is indicated that the steering angle changes greatly in the collection time period, the result is not reliable, if the collection times are greater than 10, the angle calculation result is fed back to be not reliable, otherwise, steps b, c and d are repeated to collect the angle value and calculate again; if the difference is less than 5°, it is indicated that the steering angle changes little in the collection time period, the angle calculation result is reliable, the Ang value collected currently is the median angle value; S5: it is detected whether the median angle calculation result is reliable, if yes, the next step is entered, if not, the calibration failure is reported to the ECU and the calibration request is ended; S6: the median angle data is saved and the calibration request is ended.

2. The method of claim 1, wherein: The calibration request in S1 comprises a calibration request in the development stage and a calibration request in the production stage.

3. The method of claim 2, wherein: The calibration request in the development stage comprises a calibration request in the case that the whole vehicle network is not developed and the diagnostic instrument is not developed; when the whole vehicle network is not developed, the ignition operation is performed through the key to convey the median angle calibration request to the EPS controller, and the controller executes the median angle calibration function; when the diagnostic instrument is not developed and the whole vehicle network can work normally, the CAN message is used to convey the median angle calibration request to the EPS controller, and the controller executes the median angle calibration function.

4. The method of claim 2, wherein: The calibration request in the production stage comprises a calibration request in the vehicle production stage and a calibration request in the vehicle after-sales stage; in the vehicle production stage, the UDS diagnostic command is sent to convey the median angle calibration request to the controller in the EOL test process of the whole vehicle, and the controller executes the median angle calibration function; in the vehicle after-sales stage, if the vehicle replaces the steering control system EPS, the UDS diagnostic command is sent through the after-sales diagnostic instrument to convey the median angle calibration request to the controller, and the controller executes the median angle calibration function.

5. The method of claim 1, wherein: In S2, the engine speed and vehicle speed signals of the whole vehicle are analyzed to judge whether the angle calibration condition is met.

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