Control methods, devices and vehicles for electric power steering systems

Abstract

This application relates to the field of vehicle technology, and particularly to a control method, device, and vehicle for an electric power steering system. The method includes: acquiring a first angular velocity of the electric power steering unit using a first angular velocity sensor, and acquiring a second angular velocity of the steering wheel using a second angular velocity sensor; obtaining a target steering assist torque for the current vehicle based on the first angular velocity, the second angular velocity, and a preset steering assist curve, wherein the preset steering assist curve is obtained by correcting an initial calibration curve of the electric power steering unit; and controlling the electric power steering system to provide steering assistance to the current vehicle based on the target steering assist torque. This solves the problem of large fluctuations in actual torque due to manufacturing and assembly errors, resulting in nonlinear changes in the driver's steering wheel effort. It reduces the torque fluctuation range and improves driving comfort.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a control method, device and vehicle for an electric power steering system. Background Technology

[0002] Steering assist torque is an important indicator for evaluating the steering performance of a vehicle. The magnitude and fluctuation of steering assist torque directly affect driving comfort.

[0003] In related technologies, the power assist curve of the electric power steering system is generally calibrated based on the assembly parameters of the steering drive shaft connecting the steering wheel and the steering gear, and the steering assist torque is provided according to the calibrated power assist curve.

[0004] However, due to manufacturing and assembly errors, providing steering assist torque according to the initial calibration assist curve will result in a large fluctuation range in the actual torque, leading to a poor driving experience for users. Summary of the Invention

[0005] This application provides a control method, device, and vehicle for an electric power steering system to solve the problem that the actual torque fluctuates greatly due to manufacturing and assembly errors, causing nonlinear changes in the force required for the driver to turn the steering wheel. This can reduce the torque fluctuation range and improve driving comfort.

[0006] The first aspect of this application provides a control method for an electric power steering system. A first angular velocity sensor is disposed at the input shaft position of the electric power steering gear of the vehicle, and a second angular velocity sensor is disposed between the steering wheel and the steering drive shaft of the vehicle. The method includes the following steps:

[0007] The first angular velocity of the electric power steering is obtained using the first angular velocity sensor, and the second angular velocity of the steering wheel is obtained using the second angular velocity sensor;

[0008] The target steering assist torque of the current vehicle is obtained based on the first angular velocity, the second angular velocity, and the preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system.

[0009] The electric power steering system is controlled to provide steering assistance to the current vehicle based on the target steering assist torque.

[0010] Optionally, in some embodiments, obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and a preset steering assist curve includes:

[0011] Based on the first angular velocity and the second angular velocity, the current steering assist torque is obtained by matching from the preset steering assist curve;

[0012] Based on the current steering assist torque, calculate the volatility of the electric power steering system and determine whether the volatility is less than or equal to a preset threshold.

[0013] If the volatility is less than or equal to the preset threshold, then the current steering assist torque is taken as the target steering assist torque.

[0014] Optionally, in some embodiments, after determining whether the volatility is less than or equal to the preset threshold, the method further includes:

[0015] If the volatility is greater than the preset threshold, then the current angular velocity ratio of the first angular velocity to the second angular velocity is calculated;

[0016] The product of the current steering assist torque and the ratio of the current angular velocity is taken as the target steering assist torque.

[0017] Optionally, in some embodiments, before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the method further includes:

[0018] The steering wheel is rotated at a full angular angle, and multiple first angular velocities to be calibrated of the steering wheel are obtained using the second angular velocity sensor, and multiple second angular velocities to be calibrated of the electric steering gear are obtained using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated;

[0019] Calculate the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, and obtain multiple angular velocity ratios;

[0020] The preset steering assist curve is obtained by correcting the initial calibration curve based on the multiple angular velocity ratios.

[0021] Optionally, in some embodiments, the step of correcting the initial calibration curve based on the plurality of angular velocity ratios to obtain the preset steering assist curve includes:

[0022] Based on the plurality of first angular velocities to be calibrated, determine the data to be corrected in the initial calibration curve corresponding to each of the first angular velocities to be calibrated;

[0023] The product of the angular velocity ratio corresponding to each first angular velocity to be calibrated and the data to be corrected corresponding to each first angular velocity to be calibrated is calculated to obtain multiple product results, and the preset steering assist curve is formed based on the multiple product results.

[0024] Optionally, in some embodiments, after forming the preset steering assist curve based on the plurality of product results, the method further includes:

[0025] Based on the preset steering assist curve, the electric steering system is calibrated to zero position.

[0026] Optionally, in some embodiments, after forming the preset steering assist curve based on the plurality of product results, the method further includes:

[0027] Based on the preset steering assist curve, the electric power steering system is simulated, and the fluctuation curve of the electric power steering system is generated according to the simulation results.

[0028] If the volatility of the electric power steering system is calculated to be less than or equal to a preset threshold based on the volatility curve, then the preset steering assist curve is deemed qualified.

[0029] A second aspect of this application provides a control device for an electric power steering system. A first angular velocity sensor is disposed at the input shaft position of the electric power steering gear of the vehicle, and a second angular velocity sensor is disposed between the steering wheel and the steering drive shaft of the vehicle. The device includes:

[0030] The acquisition module is used to acquire the first angular velocity of the electric power steering system using the first angular velocity sensor, and to acquire the second angular velocity of the steering wheel using the second angular velocity sensor;

[0031] The calculation module is used to obtain the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and a preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system; and

[0032] The control module is used to control the electric power steering system to provide steering assistance to the current vehicle based on the target steering assist torque.

[0033] Optionally, in some embodiments, the computing module includes:

[0034] A matching unit is used to match the current steering assist torque from the preset steering assist curve based on the first angular velocity and the second angular velocity;

[0035] The calculation unit is used to calculate the volatility of the electric power steering system based on the current steering assist torque, and to determine whether the volatility is less than or equal to a preset threshold.

[0036] The generation unit is used to take the current steering assist torque as the target steering assist torque when the volatility is less than or equal to the preset threshold.

[0037] Optionally, in some embodiments, after determining whether the volatility is less than the preset threshold, the calculation unit further includes:

[0038] A calculation subunit is used to calculate the current angular velocity ratio of the first angular velocity to the second angular velocity when the volatility is greater than the preset threshold.

[0039] A sub-unit is generated to take the product of the current steering assist torque and the ratio of the current angular velocity as the target steering assist torque.

[0040] Optionally, in some embodiments, before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the calculation module further includes:

[0041] The acquisition unit is used to rotate the steering wheel at a full angular angle and acquire multiple first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor, and acquire multiple second angular velocities to be calibrated of the electric steering gear using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated;

[0042] The calculation unit is used to calculate the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, thereby obtaining multiple angular velocity ratios;

[0043] The generation unit is used to modify the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve.

[0044] Optionally, in some embodiments, the generation unit includes:

[0045] A subunit is defined for determining, based on the plurality of first angular velocities to be calibrated, the data to be corrected in the initial calibration curve corresponding to each of the first angular velocities to be calibrated;

[0046] The calculation subunit is used to calculate the product between the angular velocity ratio corresponding to each first angular velocity to be calibrated and the data to be corrected corresponding to each first angular velocity to be calibrated to obtain multiple product results, and to form the preset steering assist curve based on the multiple product results.

[0047] Optionally, in some embodiments, after forming the preset steering assist curve based on the plurality of product results, the calculation subunit further includes:

[0048] The calibration component is used to perform zero-position calibration of the electric power steering system based on the preset steering assist curve.

[0049] Optionally, in some embodiments, after forming the preset steering assist curve based on the plurality of product results, the calibration subunit further includes:

[0050] The simulation sub-component is used to simulate the electric power steering system based on the preset steering assist curve, and generate the fluctuation curve of the electric power steering system according to the simulation results.

[0051] The determination sub-component is used to determine that the preset steering assist curve is qualified when the volatility of the electric power steering system calculated based on the volatility curve is less than or equal to a preset threshold.

[0052] A third aspect of this application provides a vehicle including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a control method for an electric power steering system as described in the above embodiments.

[0053] Therefore, by installing an angular velocity sensor under the steering wheel to obtain the steering wheel's angular velocity, and rotating the steering wheel at a full angular radius, the angular velocity ratio of the electric steering unit to the steering wheel's angular velocity is calculated. This ratio is used to correct the initial calibration curve, resulting in a preset steering assist curve. Then, based on the first angular velocity of the electric steering unit, the second angular velocity of the steering wheel, and the preset steering assist curve, the target steering assist torque for the current vehicle is obtained. The electric steering assist system is then controlled to provide steering assistance to the current vehicle based on the target steering assist torque. This solves the problem of large fluctuations in actual torque caused by manufacturing and assembly errors, resulting in non-linear changes in the driver's steering wheel effort. It reduces torque fluctuations and improves driving comfort.

[0054] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0055] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0056] Figure 1 This is a schematic diagram of a steering drive shaft in related technologies;

[0057] Figure 2 This is a schematic diagram of the angular velocity fluctuation curve of the steering drive shaft in related technologies;

[0058] Figure 3 This is a flowchart of a control method for an electric power steering system provided according to an embodiment of this application;

[0059] Figure 4 This is a schematic diagram of an electric power steering system according to an embodiment of this application;

[0060] Figure 5 This is a block diagram of the control device for an electric power steering system provided according to an embodiment of this application;

[0061] Figure 6 This is a structural schematic diagram of a vehicle provided according to an embodiment of this application. Detailed Implementation

[0062] The embodiments of this application are described in detail below. Examples of these embodiments 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 intended to explain this application, and should not be construed as limiting this application.

[0063] Before introducing the control method of the electric power steering system in the embodiments of this application, let's first introduce the steering drive shaft in the related art.

[0064] Figure 1 This is a schematic diagram of a steering drive shaft in related technologies, where 1 is a universal joint, 2 is a fastening bolt, and 3 is a steering drive shaft.

[0065] The steering drive shaft 3, which connects the steering wheel and the steering gear, is generally divided into three or more sections. Each section is connected by a universal joint, and the shafts are connected by cross-shaped universal joints. The fluctuation of hand force is equivalent to the fluctuation of angular velocity at both ends of the universal joint.

[0066] To facilitate understanding, let's first introduce the transmission characteristics of a cross-shaped universal joint. A universal joint where the upper and lower ends rotate at different speeds can be called a non-uniform velocity universal joint. The rules governing this are as follows:

[0067] 1. The larger the included angle of a single universal joint, the greater the fluctuation amplitude, indicating that the fluctuation amplitude and the included angle are strongly correlated;

[0068] 2. The fluctuations are very regular, resembling a sine wave, such as... Figure 2 As shown.

[0069] In related technologies, in order to eliminate fluctuations, the angle (phase angle) of the forks at both ends of the drive shaft between the two universal joints is usually adjusted so that the fluctuation curves caused by the two universal joints cancel each other out, so that the torque fluctuation range control target value K≤5%. Although the theoretically designed torque fluctuation range control target value K≤5%, in reality, due to manufacturing errors and assembly errors, the actual torque fluctuation is large and can be perceived by the driver.

[0070] To address the issue of large fluctuations in actual torque caused by manufacturing and assembly errors in related technologies, an angular velocity sensor can be installed below the steering wheel to obtain the steering wheel's angular velocity. By rotating the steering wheel at full angular radius, the angular velocity ratio between the electric power steering unit and the steering wheel can be calculated. This ratio is then used to correct the initial calibration curve, resulting in a preset steering assist curve. Based on the first angular velocity of the electric power steering unit, the second angular velocity of the steering wheel, and the preset steering assist curve, the target steering assist torque for the current vehicle is obtained. The electric power steering system is then controlled to provide steering assistance to the current vehicle based on the target steering assist torque, thereby reducing the torque fluctuation range and improving driving comfort.

[0071] Specifically, Figure 3 This is a flowchart illustrating a control method for an electric power steering system provided in an embodiment of this application.

[0072] like Figure 3 As shown, the control method of the electric power steering system includes the following steps:

[0073] In step S301, the first angular velocity of the electric steering gear is obtained using the first angular velocity sensor, and the second angular velocity of the steering wheel is obtained using the second angular velocity sensor.

[0074] Specifically, in this embodiment of the application, a first angular velocity sensor can be set at the input shaft of the electric power steering system of the vehicle to obtain a first angular velocity, and a second angular velocity sensor can be set between the steering wheel and the steering transmission shaft of the vehicle to obtain a second angular velocity.

[0075] In actual implementation, such as Figure 4 As shown, the electric power steering system of this application embodiment may include an electric power steering unit (4), a steering column belt drive shaft assembly (5), and a steering wheel assembly (6). Currently, the electric power steering unit (4) has a built-in first angle sensor at the input shaft position, which can monitor the first angular velocity at this position. In this application embodiment, a second angle sensor (7) needs to be added under the steering wheel to monitor the second angular velocity at this position.

[0076] In step S302, the target steering assist torque of the current vehicle is obtained based on the first angular velocity, the second angular velocity, and the preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system.

[0077] The preset steering assist curve and the initial calibration curve can both be curves generated from the correspondence between multiple angular velocities of the steering wheel, multiple angular velocities of the electric steering unit, and steering assist torque.

[0078] It is understandable that errors in the actual manufacturing and assembly process of electric power steering systems can easily cause large fluctuations in actual torque, resulting in nonlinear changes in the driver's hand force. That is, when turning the steering wheel, the driver feels that the hand force is sometimes light and sometimes heavy, leading to poor driving comfort. Therefore, the embodiments of this application can determine the target steering assist torque of the current vehicle by modifying the initial calibration curve to obtain a preset steering assist curve, thereby providing steering assistance based on the target steering assist torque, effectively reducing the torque fluctuation range and improving driving comfort.

[0079] It should be noted that there are many ways to obtain the target steering assist torque of the current vehicle based on the preset steering assist curve, which will be explained in detail below with specific examples.

[0080] As one possible implementation, in some embodiments, the target steering assist torque of the current vehicle is obtained based on a first angular velocity, a second angular velocity, and a preset steering assist curve. This includes: matching the current steering assist torque from the preset steering assist curve based on the first and second angular velocities; calculating the volatility of the electric power steering system based on the current steering assist torque, and determining whether the volatility is less than or equal to a preset threshold; if the volatility is less than or equal to the preset threshold, then the current steering assist torque is taken as the target steering assist torque. The preset threshold can be pre-set by the user, obtained through a limited number of experiments, or obtained through a limited number of computer simulations; no specific limitation is made here. Preferably, the preset threshold can be 5%.

[0081] It is understandable that due to large manufacturing and assembly errors, or due to long-term use, the torque fluctuation range may be large. Therefore, the embodiments of this application can calculate whether the fluctuation rate of the electric power steering system is within the driving comfort range (i.e., the fluctuation rate of the electric power steering system is less than or equal to a preset threshold).

[0082] Specifically, in this embodiment, the current steering assist torque can be obtained by matching the first angular velocity of the current electric steering gear and the second angular velocity of the current steering wheel from the preset steering assist curve, and the volatility of the electric power assist system can be calculated based on the current steering assist torque. If the calculated volatility is less than or equal to a preset threshold, it indicates that the torque fluctuation range is within the driving comfort range. In this embodiment, the current steering assist torque can be directly used as the target steering assist torque.

[0083] Furthermore, in some embodiments, after determining whether the volatility is less than or equal to a preset threshold, the method further includes: if the volatility is greater than the preset threshold, calculating the current angular velocity ratio of the first angular velocity to the second angular velocity; and using the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque.

[0084] It is understandable that if the fluctuation rate of the electric power steering system is greater than the preset threshold, it means that the torque fluctuation range is large, which will lead to poor driving comfort for the user. Therefore, the embodiments of this application can calculate the ratio of the first angular velocity of the current electric power steering to the second angular velocity of the current steering wheel, and use the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque to correct the current steering assist torque so that the torque fluctuation range is within the driving comfort range.

[0085] Furthermore, in some embodiments, before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the method further includes: rotating the steering wheel at full angular angle; acquiring multiple first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor; and acquiring multiple second angular velocities to be calibrated of the electric steering unit using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated; calculating the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, thereby obtaining multiple angular velocity ratios; and correcting the initial calibration curve based on the multiple angular velocity ratios to obtain the preset steering assist curve.

[0086] This application embodiment can reduce the torque fluctuation range by correcting the initial calibration curve. Specifically, the steering wheel is rotated at a full turning angle to obtain the first and second angular velocities to be calibrated at the same steering wheel turning angle. For example, the steering wheel is rotated 10 degrees clockwise, the first angular velocity to be calibrated of the steering wheel is obtained using the second angular velocity sensor, and the second angular velocity to be calibrated of the electric steering gear is obtained using the first angular velocity sensor. Then the steering wheel is rotated 20 degrees clockwise to obtain the first angular velocity to be calibrated of the steering wheel and the second angular velocity to be calibrated of the electric steering gear, until the steering wheel is rotated at a full turning angle.

[0087] After obtaining multiple sets of one-to-one corresponding first and second angular velocities to be calibrated, the ratio of each first angular velocity to be calibrated to the corresponding second angular velocity to be calibrated is calculated to obtain multiple angular velocity ratios. The initial calibration curve is then corrected using these multiple angular velocity ratios.

[0088] Optionally, in some embodiments, the preset steering assist curve is obtained by correcting the initial calibration curve based on multiple angular velocity ratios, including: determining the data to be corrected corresponding to each first angular velocity to be calibrated in the initial calibration curve based on multiple first angular velocities to be calibrated; calculating the product between the angular velocity ratio corresponding to each first angular velocity to be calibrated and the data to be corrected corresponding to each first angular velocity to be calibrated to obtain multiple product results, and forming the preset steering assist curve based on the multiple product results.

[0089] Those skilled in the art will understand that when the torque fluctuation reaches its maximum value, it is equivalent to an increase in the power assist produced by the steering system. The power assist curve is multiplied by the corresponding fluctuation ratio, meaning that the increase in the power assist of the steering system no longer requires a large input torque (driver's operating force) to achieve torque balance, thereby achieving the purpose of reducing the torque fluctuation range.

[0090] In this embodiment, the initial calibration curve can be corrected by multiplying it by the corresponding fluctuation ratio to obtain a preset steering assist curve. Specifically, the data to be corrected for each angular velocity to be calibrated in the initial calibration curve is determined, and the angular velocity ratio corresponding to the first angular velocity to be calibrated is obtained, that is, the ratio of the first angular velocity to be calibrated to the second angular velocity to be calibrated corresponding to the first calibrated angular velocity. The product of the data to be corrected for each angular velocity to be calibrated and the angular velocity ratio is calculated to obtain multiple product results, and the multiple product results are used to form the preset steering assist curve.

[0091] Optionally, in some embodiments, after forming a preset steering assist curve based on multiple product results, the method further includes: simulating the electric power steering system based on the preset steering assist curve, and generating a fluctuation curve diagram of the electric power steering system based on the simulation results; if the fluctuation rate of the electric power steering system calculated from the fluctuation curve diagram is less than or equal to a preset threshold, then the preset steering assist curve is deemed qualified.

[0092] Understandably, in order to ensure that the preset steering assist curve obtained by correcting the initial calibration curve of the electric power steering system can effectively reduce the volatility of the electric power steering system, this application embodiment can, after obtaining the preset steering assist curve, use the preset steering assist curve to simulate the electric power steering system, generate a volatility curve diagram of the electric power steering system based on the simulation results, and calculate the volatility of the electric power steering system based on the volatility curve diagram. If the calculated volatility of the electric power steering system is less than a preset threshold, the preset steering assist curve is deemed qualified. That is, controlling the electric power steering system based on the preset steering assist curve can effectively improve the torque fluctuation caused by errors in the actual manufacturing and assembly process of the electric power steering system.

[0093] In addition, if the calculated volatility of the electric power steering system is greater than a preset threshold, the preset steering assist curve is deemed unqualified. That is, controlling the electric power steering system based on the preset steering assist curve has not effectively improved the torque fluctuation caused by errors in the actual manufacturing and assembly process of the electric power steering system.

[0094] Optionally, in some embodiments, after forming a preset steering assist curve based on multiple product results, the method further includes: zero-position calibration of the electric steering system based on the preset steering assist curve.

[0095] It is understandable that, in order to improve steering quality and ensure that the direction of the wheels is consistent with the actual direction of the vehicle, this embodiment of the application can perform zero-position calibration of the electric steering system based on a preset steering assist curve before the vehicle rolls off the production line, in order to prevent the vehicle from veering off course.

[0096] In step S303, the electric power steering system is controlled to provide steering assistance to the current vehicle based on the target steering assist torque.

[0097] Specifically, after obtaining the target steering torque of the current vehicle based on the first angular velocity of the current electric steering gear, the second angular velocity of the current steering wheel, and the preset steering assist curve, the electric steering assist system can be controlled to provide steering assistance to the current vehicle based on the target steering assist torque. This improves the torque fluctuation caused by errors in the actual manufacturing and assembly process of the electric steering assist system, reduces the range of torque fluctuation, and improves the driver's driving comfort.

[0098] Therefore, the embodiments of this application can further reduce the torque fluctuation range based on the original initial calibration curve, avoid torque fluctuations caused by manufacturing and assembly errors, and optimize the driving experience.

[0099] In summary, this embodiment of the application can add a logic to the electric steering controller to enable self-learning before the steering wheel is calibrated to the center position. The self-learning content is as follows: 1. First, the electric steering system has initial calibration assist curve data. Before the vehicle rolls off the production line and the steering zero-position calibration is performed, the steering controller rotates the steering wheel at a full turning angle. The controller receives the first and second angular velocities monitored by the angle sensors and calculates the ratio of the angular velocities of the two angle sensors at this time. 2. Then, the initial calibration assist curve data of the electric steering system is multiplied by this ratio to form the final steering assist curve data. The principle is that when the torque fluctuation reaches its maximum value, it is equivalent to an increase in the assist generated by the steering system. The assist curve is multiplied by the corresponding fluctuation ratio, meaning that the increase in steering assist no longer requires a large input torque (driver's operating force). This achieves torque balance and reduces the torque fluctuation range.

[0100] According to the control method of the electric power steering system proposed in this application, the angular velocity of the steering wheel is obtained by installing an angular velocity sensor under the steering wheel. The steering wheel is rotated at a full turning angle, and the angular velocity ratio between the electric power steering unit and the steering wheel is calculated. The initial calibration curve is corrected using this ratio to obtain a preset steering assist curve. Then, based on the first angular velocity of the electric power steering unit, the second angular velocity of the steering wheel, and the preset steering assist curve, the target steering assist torque for the current vehicle is obtained. The electric power steering system is then controlled to provide steering assistance to the current vehicle based on the target steering assist torque. This solves the problem of large fluctuations in actual torque caused by manufacturing and assembly errors, resulting in nonlinear changes in the driver's steering wheel effort. It reduces the torque fluctuation range and improves driving comfort.

[0101] Next, the control device for the electric power steering system according to the embodiments of this application is described with reference to the accompanying drawings.

[0102] Figure 5 This is a block diagram of the control device of the electric power steering system according to an embodiment of this application.

[0103] like Figure 5 As shown, the control device 10 of the electric power steering system includes: an acquisition module 100, a calculation module 200, and a control module 300.

[0104] The acquisition module 100 is used to acquire the first angular velocity of the electric steering gear using the first angular velocity sensor, and to acquire the second angular velocity of the steering wheel using the second angular velocity sensor.

[0105] The calculation module 200 is used to obtain the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity and the preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system.

[0106] The control module 300 is used to control the electric power steering system to provide steering assistance to the current vehicle based on the target steering assist torque.

[0107] Optionally, in some embodiments, the calculation module includes: a matching unit, a calculation unit, and a generation unit.

[0108] The matching unit is used to obtain the current steering assist torque from the preset steering assist curve based on the first angular velocity and the second angular velocity.

[0109] The calculation unit is used to calculate the volatility of the electric power steering system based on the current steering assist torque, and to determine whether the volatility is less than or equal to a preset threshold.

[0110] The generation unit is used to take the current steering assist torque as the target steering assist torque when the volatility is less than or equal to a preset threshold.

[0111] Optionally, in some embodiments, after determining whether the volatility is less than a preset threshold, the calculation unit further includes a calculation subunit and a generation subunit.

[0112] The calculation subunit is used to calculate the current angular velocity ratio of the first angular velocity to the second angular velocity when the volatility is greater than a preset threshold.

[0113] A generation subunit is used to take the product of the current steering assist torque and the current angular velocity as the target steering assist torque. Optionally, in some embodiments, before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the calculation module 200 further includes: an acquisition unit, a calculation unit, and a generation unit.

[0114] The acquisition unit is used to rotate the steering wheel at all angles and acquire multiple first angular velocities to be calibrated of the steering wheel using a second angular velocity sensor, and acquire multiple second angular velocities to be calibrated of the electric steering unit using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated.

[0115] The calculation unit is used to calculate the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, and to obtain multiple angular velocity ratios.

[0116] The generation unit is used to correct the initial calibration curve based on multiple angular velocity ratios to obtain a preset steering assist curve.

[0117] Optionally, in some embodiments, the generating unit includes: a determining subunit and a calculating subunit.

[0118] The determination sub-unit is used to determine the data to be corrected corresponding to each first angular velocity to be calibrated in the initial calibration curve based on multiple first angular velocities to be calibrated.

[0119] The calculation subunit is used to calculate the product between the angular velocity ratio corresponding to each first angular velocity to be calibrated and the data to be corrected corresponding to each first angular velocity to be calibrated to obtain multiple product results, and to form a preset steering assist curve based on the multiple product results.

[0120] Optionally, in some embodiments, after forming a preset steering assist curve based on multiple product results, the calculation subunit further includes a calibration subunit.

[0121] The calibration sub-component is used to calibrate the electric power steering system to zero position based on a preset steering assist curve.

[0122] Optionally, in some embodiments, after forming a preset steering assist curve based on multiple product results, the calibration subunit further includes: a simulation subcomponent and a determination subcomponent.

[0123] The simulation sub-component is used to simulate the electric power steering system based on a preset steering assist curve, and generate a fluctuation curve diagram of the electric power steering system based on the simulation results.

[0124] The judgment sub-component is used to determine that the preset power steering curve is qualified when the volatility of the electric power steering system calculated from the volatility curve is less than or equal to a preset threshold.

[0125] It should be noted that the foregoing explanation of the control method embodiment for the electric power steering system also applies to the control device of the electric power steering system in this embodiment, and will not be repeated here.

[0126] The control device for the electric power steering system proposed in this application obtains the angular velocity of the steering wheel by installing an angular velocity sensor below the steering wheel. The steering wheel is rotated at a full turning angle, and the angular velocity ratio between the electric power steering unit and the steering wheel is calculated. This angular velocity ratio is then used to correct the initial calibration curve to obtain a preset steering assist curve. Based on the first angular velocity of the electric power steering unit, the second angular velocity of the steering wheel, and the preset steering assist curve, the target steering assist torque for the current vehicle is obtained. The electric power steering system is then controlled to provide steering assistance to the current vehicle based on the target steering assist torque. This solves the problem of large fluctuations in actual torque caused by manufacturing and assembly errors, resulting in nonlinear changes in the driver's steering wheel effort. It reduces the torque fluctuation range and improves driving comfort.

[0127] Figure 6 A schematic diagram of the structure of a vehicle provided in an embodiment of this application. The vehicle may include:

[0128] The memory 601, the processor 602, and the computer program stored on the memory 601 and capable of running on the processor 602.

[0129] When the processor 602 executes the program, it implements the control method of the electric power steering system provided in the above embodiments.

[0130] Furthermore, the vehicle also includes:

[0131] Communication interface 603 is used for communication between memory 601 and processor 602.

[0132] The memory 601 is used to store computer programs that can run on the processor 602.

[0133] The memory 601 may include high-speed RAM (Random Access Memory) memory, and may also include non-volatile memory, such as at least one disk storage.

[0134] If the memory 601, processor 602, and communication interface 603 are implemented independently, then the communication interface 603, memory 601, and processor 602 can be interconnected via a bus to complete communication between them. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0135] Optionally, in a specific implementation, if the memory 601, processor 602, and communication interface 603 are integrated on a single chip, then the memory 601, processor 602, and communication interface 603 can communicate with each other through an internal interface.

[0136] The processor 602 may be a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of this application.

[0137] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0138] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0139] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0140] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (FPGAs), field-programmable gate arrays (FPGAs), etc.

[0141] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0142] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A control method for an electric power steering system, characterized in that, A first angular velocity sensor is installed at the input shaft of the vehicle's electric power steering system, and a second angular velocity sensor is installed between the vehicle's steering wheel and the steering drive shaft. The method includes the following steps: The first angular velocity of the electric power steering is obtained using the first angular velocity sensor, and the second angular velocity of the steering wheel is obtained using the second angular velocity sensor; The target steering assist torque of the current vehicle is obtained based on the first angular velocity, the second angular velocity, and a preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system; and The electric power steering system is controlled to provide steering assistance to the current vehicle based on the target steering assist torque. The step of obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and a preset steering assist curve includes: matching the current steering assist torque from the preset steering assist curve based on the first angular velocity and the second angular velocity; calculating the volatility of the electric power steering system based on the current steering assist torque, and determining whether the volatility is less than or equal to a preset threshold; if the volatility is less than or equal to the preset threshold, then using the current steering assist torque as the target steering assist torque. After determining whether the volatility is less than or equal to the preset threshold, the method further includes: if the volatility is greater than the preset threshold, calculating the current angular velocity ratio of the first angular velocity to the second angular velocity; and using the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque.

2. The method according to claim 1, characterized in that, Before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the method further includes: The steering wheel is rotated at a full angular angle, and multiple first angular velocities to be calibrated of the steering wheel are obtained using the second angular velocity sensor, and multiple second angular velocities to be calibrated of the electric steering gear are obtained using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated; Calculate the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, and obtain multiple angular velocity ratios; The preset steering assist curve is obtained by correcting the initial calibration curve based on the multiple angular velocity ratios.

3. The method according to claim 2, characterized in that, The step of correcting the initial calibration curve based on the multiple angular velocity ratios to obtain the preset steering assist curve includes: Based on the plurality of first angular velocities to be calibrated, determine the data to be corrected in the initial calibration curve corresponding to each of the first angular velocities to be calibrated; The product of the angular velocity ratio corresponding to each first angular velocity to be calibrated and the data to be corrected corresponding to each first angular velocity to be calibrated is calculated to obtain multiple product results, and the preset steering assist curve is formed based on the multiple product results.

4. A control device for an electric power steering system, characterized in that, A first angular velocity sensor is installed at the input shaft of the vehicle's electric power steering system, and a second angular velocity sensor is installed between the vehicle's steering wheel and the steering drive shaft. The device includes: The acquisition module is used to acquire the first angular velocity of the electric power steering system using the first angular velocity sensor, and to acquire the second angular velocity of the steering wheel using the second angular velocity sensor; The calculation module is used to obtain the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and a preset steering assist curve, wherein the preset steering assist curve is obtained by correcting the initial calibration curve of the electric steering system; and The control module is used to control the electric power steering system to provide steering assistance to the current vehicle based on the target steering assist torque. The computing module includes: A matching unit is used to match the current steering assist torque from the preset steering assist curve based on the first angular velocity and the second angular velocity; The calculation unit is used to calculate the volatility of the electric power steering system based on the current steering assist torque, and to determine whether the volatility is less than or equal to a preset threshold. A generation unit is used to take the current steering assist torque as the target steering assist torque when the volatility is less than or equal to the preset threshold. After determining whether the volatility is less than the preset threshold, the calculation unit further includes: A calculation subunit is used to calculate the current angular velocity ratio of the first angular velocity to the second angular velocity when the volatility is greater than the preset threshold. A sub-unit is generated to take the product of the current steering assist torque and the ratio of the current angular velocity as the target steering assist torque.

5. The apparatus according to claim 4, characterized in that, Before obtaining the target steering assist torque of the current vehicle based on the first angular velocity, the second angular velocity, and the preset steering assist curve, the calculation module further includes: The acquisition unit is used to rotate the steering wheel at a full angular angle and acquire multiple first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor, and acquire multiple second angular velocities to be calibrated of the electric steering gear using the first angular velocity sensor, wherein the multiple first angular velocities to be calibrated correspond one-to-one with the multiple second angular velocities to be calibrated; The calculation unit is used to calculate the ratio of each first angular velocity to be calibrated to each second angular velocity to be calibrated corresponding to each first angular velocity to be calibrated, thereby obtaining multiple angular velocity ratios; The generation unit is used to modify the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve.

6. A vehicle, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the control method for the electric power steering system as described in any one of claims 1-3.

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