Control method and device of electric power steering system and vehicle

Abstract

The invention relates to the technical field of vehicles, in particular to a control method and device of an electric power steering system and a vehicle. The method comprises the steps that a first angular velocity of an electric steering gear is obtained through a first angular velocity sensor, and a second angular velocity of a steering wheel is obtained through a second angular velocity sensor; the target power-assisted steering torque of the current vehicle is obtained according to the first angular speed, the second angular speed and a preset power-assisted steering curve, and the preset power-assisted steering curve is obtained by correcting an initial calibration curve of the electric steering gear; and controlling the electric power-assisted steering system to carry out power-assisted steering on the current vehicle based on the target power-assisted steering torque. Therefore, the problems that due to manufacturing errors and assembly errors, the fluctuation range of actual torque is large, and hand power nonlinear changes occur when a driver rotates the steering wheel are solved, the fluctuation range of the torque can be reduced, and the driving comfort can be improved.

Description

Technical Field

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

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

[0003] In the related art, the power assist curve of the electric steering gear is generally calibrated based on the assembly parameters of the steering transmission 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 errors and assembly errors, providing steering assist torque according to the initial calibrated assist curve will cause a large fluctuation range of the actual torque, resulting in a poor driving experience for users. Summary of the invention

[0005] The present application provides a control method, device and vehicle for an electric power steering system to solve the problem that the actual torque has a large fluctuation range due to manufacturing errors and assembly errors, and the driver's hand force will change nonlinearly when turning the steering wheel. The torque fluctuation range can be reduced and driving comfort can be improved.

[0006] The first aspect of the present application provides a control method for an electric power steering system, wherein a first angular velocity sensor is provided at the position of an electric steering input shaft of a vehicle, and a second angular velocity sensor is provided between a steering wheel and a steering transmission shaft of the vehicle, wherein the method comprises the following steps:

[0007] Using the first angular velocity sensor to acquire a first angular velocity of the electric steering gear, and using the second angular velocity sensor to acquire a second angular velocity of the steering wheel;

[0008] Obtaining a target steering assist torque of the current vehicle according to 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 steering gear;

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

[0010] Optionally, in some embodiments, obtaining a target steering assist torque of the current vehicle according to 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, matching and obtaining a current steering assist torque from the preset steering assist curve;

[0012] Calculating a fluctuation rate of the electric power steering system based on the current steering assist torque, and determining whether the fluctuation rate is less than or equal to a preset threshold;

[0013] If the fluctuation rate is less than or equal to the preset threshold, the current steering assist torque is used 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 fluctuation rate is greater than the preset threshold, calculating a current angular velocity ratio of the first angular velocity to the second angular velocity;

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

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

[0018] Rotate the steering wheel at a full angle, use the second angular velocity sensor to obtain a plurality of first angular velocities to be calibrated of the steering wheel, and use the first angular velocity sensor to obtain a plurality of second angular velocities to be calibrated of the electric steering gear, wherein the plurality of first angular velocities to be calibrated correspond to the plurality of second angular velocities to be calibrated one by one;

[0019] 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, to obtain a plurality of angular velocity ratios;

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

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

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

[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 a plurality of product results, and the preset steering assist curve is formed according to the plurality of product results.

[0024] Optionally, in some embodiments, after forming the preset steering assist curve according to the multiple product results, the method further includes:

[0025] Based on the preset steering assist curve, the electric steering gear is zero-calibrated.

[0026] Optionally, in some embodiments, after forming the preset steering assist curve according to the multiple product results, the method further includes:

[0027] Based on the preset steering assist curve, simulating the electric power steering system, and generating a fluctuation curve diagram of the electric power steering system according to the simulation result;

[0028] If the fluctuation rate of the electric power steering system calculated according to the fluctuation curve diagram is less than or equal to a preset threshold, it is determined that the preset steering assist curve is qualified.

[0029] A second aspect of the present application provides a control device for an electric power steering system, wherein a first angular velocity sensor is provided at the input shaft position of an electric steering gear of a vehicle, and a second angular velocity sensor is provided between a steering wheel and a steering transmission shaft of the vehicle, wherein the device comprises:

[0030] an acquisition module, configured to acquire a first angular velocity of the electric steering gear by using the first angular velocity sensor, and acquire a second angular velocity of the steering wheel by using the second angular velocity sensor;

[0031] a calculation module, configured to obtain a target steering assist torque of the current vehicle according to 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 steering gear; 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 assistance torque.

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

[0034] a matching unit, configured to obtain a current steering assist torque by matching the preset steering assist curve based on the first angular velocity and the second angular velocity;

[0035] a calculation unit, configured to calculate a fluctuation rate of the electric power steering system based on the current steering assist torque, and determine whether the fluctuation rate is less than or equal to a preset threshold;

[0036] A generating unit is used to use the current steering assist torque as the target steering assist torque when the fluctuation rate 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, configured to calculate a current angular velocity ratio of the first angular velocity to the second angular velocity when the fluctuation rate is greater than the preset threshold;

[0039] A generating subunit is used to take the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque.

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

[0041] an acquisition unit, configured to rotate the steering wheel at a full angle, and acquire a plurality of first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor, and acquire a plurality of second angular velocities to be calibrated of the electric steering gear using the first angular velocity sensor, wherein the plurality of first angular velocities to be calibrated correspond to the plurality of second angular velocities to be calibrated one by one;

[0042] a calculation unit, configured to calculate a 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, to obtain a plurality of angular velocity ratios;

[0043] A generating unit is used to correct the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve.

[0044] Optionally, in some embodiments, the generating unit comprises:

[0045] a determination subunit, configured to determine, based on the plurality of first angular velocities to be calibrated, data to be corrected corresponding to each of the first angular velocities to be calibrated in the initial calibration curve;

[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 form the preset steering assist curve according to the multiple product results.

[0047] Optionally, in some embodiments, after forming the preset steering assist curve according to the multiple product results, the calculation subunit further includes:

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

[0049] Optionally, in some embodiments, after forming the preset steering assist curve according to the multiple product results, the calibration subunit further includes:

[0050] A simulation subcomponent, used for 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 according to the simulation result;

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

[0052] A third aspect of the present application provides a vehicle, comprising: 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 the control method of the electric power steering system as described in the above embodiment.

[0053] Therefore, by installing an angular velocity sensor under the steering wheel to obtain the angular velocity of the steering wheel, the steering wheel is turned at a full angle, the angular velocity ratio of the angular velocity of the electric steering gear and the angular velocity of the steering wheel is calculated, and the initial calibration curve is corrected by the angular velocity ratio to obtain a preset steering assist curve, and then the target steering assist torque of the current vehicle is obtained according to the first angular velocity of the electric steering gear, the second angular velocity of the steering wheel and the preset steering assist curve, and the electric steering assist system is controlled to perform steering assist on the current vehicle based on the target steering assist torque. In this way, the problem that the actual torque fluctuation range is large due to manufacturing errors and assembly errors, and the driver's hand force will change nonlinearly when turning the steering wheel is solved, the torque fluctuation range can be reduced, and driving comfort can be improved.

[0054] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0056] Figure 1 It is a schematic diagram of a steering transmission shaft in the related art;

[0057] Figure 2 is a schematic diagram of an angular velocity fluctuation curve of a steering transmission shaft in the related art;

[0058] Figure 3 A flowchart of a control method for an electric power steering system provided according to an embodiment of the present application;

[0059] Figure 4 A schematic diagram of the principle of an electric power steering system provided according to an embodiment of the present application;

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

[0061] Figure 6 It is a schematic diagram of the structure of a vehicle provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0062] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0063] Before introducing the control method of the electric power steering system according to the embodiment of the present application, the steering transmission shaft in the related art is first introduced.

[0064] Figure 1 It is a schematic diagram of a steering transmission shaft in the related art, wherein 1 is a universal joint, 2 is a fastening bolt, and 3 is a steering transmission shaft.

[0065] The steering transmission shaft 3 connecting the steering wheel and the steering gear is generally divided into three sections or more. A universal joint is used to connect each section, and the shafts are connected by cross-axis 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 the cross-axis universal joint. If the speeds of the upper and lower ends of a single universal joint are not synchronized, it can be called an unequal-speed universal joint. The rules are as follows:

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

[0068] 2. The fluctuation is very regular, showing a sine wave, such as Figure 2 shown.

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

[0070] In order to solve the problem of a large fluctuation range of actual torque caused by manufacturing errors and assembly errors in related technologies, an angular velocity sensor can be installed under the steering wheel to obtain the angular velocity of the steering wheel, the steering wheel can be turned at a full angle, the angular velocity ratio of the angular velocity of the electric steering gear and the angular velocity of the steering wheel can be calculated, and the initial calibration curve can be corrected by the angular velocity ratio to obtain a preset steering assist curve, and then the target steering assist torque of the current vehicle can be obtained according to the first angular velocity of the electric steering gear, the second angular velocity of the steering wheel and the preset steering assist curve, and the electric steering assist system can be 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 A flow chart of a control method for an electric power steering system provided in an embodiment of the present application.

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

[0073] In step S301 , a first angular velocity sensor is used to acquire a first angular velocity of the electric power steering gear, and a second angular velocity sensor is used to acquire a second angular velocity of the steering wheel.

[0074] Specifically, the embodiment of the present application can be achieved by setting a first angular velocity sensor at the position of the electric steering input shaft of the vehicle, and using the first angle sensor to obtain a first angular velocity, setting a second angular velocity sensor between the steering wheel and the steering drive shaft of the vehicle, and using the second angular velocity sensor to obtain a second angular velocity.

[0075] In the actual implementation process, Figure 4 As shown, the electric power steering system of the embodiment of the present application may include an electric steering gear (4), a steering column with a drive shaft assembly (5), and a steering wheel assembly (6). Currently, a first angle sensor is provided at the position of the input shaft of the electric steering gear (4), and the first angular velocity of this position can be monitored by the first angle sensor. The embodiment of the present application needs to add a second angle sensor (7) under the steering wheel to monitor the second angular velocity of this position.

[0076] In step S302, a target steering assist torque of the current vehicle is obtained according to 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 steering gear.

[0077] The preset steering assist curve and the initial calibration curve may be curves generated by the correspondence between a plurality of angular velocities of the steering wheel, a plurality of angular velocities of the electric steering gear, and the steering assist torque.

[0078] It is understandable that the errors generated in the actual manufacturing and assembly process of the electric power steering system can easily cause large fluctuations in the actual torque, causing the driver to experience nonlinear changes in hand force. That is, when turning the steering wheel, the driver feels that the hand force is sometimes light and sometimes heavy, resulting in poor driving comfort for the user. Therefore, the embodiment of the present application can determine the target steering assist torque of the current vehicle by obtaining a preset steering assist curve by correcting the initial calibration curve, thereby performing 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 according to the preset steering assist curve, which will be described in detail below in conjunction with specific embodiments.

[0080] As a possible implementation method, in some embodiments, the target steering assist torque of the current vehicle is obtained according to the first angular velocity, the second angular velocity and the preset steering assist curve, including: 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; based on the current steering assist torque, the fluctuation rate of the electric power steering system is calculated, and it is determined whether the fluctuation rate is less than or equal to the preset threshold; if the fluctuation rate is less than or equal to the preset threshold, the current steering assist torque is used as the target steering assist torque. The preset threshold can be pre-set by the user, can be obtained through a limited number of experiments, or can be obtained through a limited number of computer simulations, which is not specifically limited here. Preferably, the preset threshold can be 5%.

[0081] It is understandable that due to large manufacturing errors and assembly errors, or due to long-term use, the torque fluctuation range will be larger. Therefore, the embodiment of the present application can calculate whether the fluctuation rate of the electric power assist system is in the driving comfort range (that is, the fluctuation rate of the electric power assist system is less than or equal to the preset threshold).

[0082] Specifically, the embodiment of the present application can match the current steering assist torque from a preset steering assist curve according to the first angular velocity of the current electric steering gear and the second angular velocity of the current steering wheel, and calculate the fluctuation rate of the electric power assist system based on the current steering assist torque. If the calculated fluctuation rate is less than or equal to the preset threshold, it means that the torque fluctuation range is in the driving comfort range. The embodiment of the present application can directly use the current steering assist torque 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, it also 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 taking the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque.

[0084] It can be understood that if the fluctuation rate of the electric power-assist system is greater than the preset threshold, it means that the torque fluctuation range is large at this time, which will lead to poor driving comfort for the user. Therefore, the embodiment of the present application can calculate the angular velocity ratio of the first angular velocity of the current electric steering gear and 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 according to the first angular velocity, the second angular velocity and the preset steering assist curve, it also includes: rotating the steering wheel at a full angle, obtaining multiple first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor, and obtaining 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 to 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, to obtain multiple angular velocity ratios; and correcting the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve.

[0086] The embodiments of the present application can reduce the fluctuation range of the torque by correcting the initial calibration curve. Specifically, the steering wheel is turned at a full angle to obtain the first angular velocity to be calibrated and the second angular velocity to be calibrated at the same steering wheel angle. For example, the steering wheel is turned clockwise by 10 degrees, and the first angular velocity sensor is used to obtain the first angular velocity of the steering wheel to be calibrated, and the first angular velocity sensor is used to obtain the second angular velocity of the electric steering gear to be calibrated, and then the steering wheel is turned clockwise by 20 degrees to obtain the first angular velocity of the steering wheel to be calibrated and the second angular velocity of the electric steering gear to be calibrated, until the steering wheel is turned at a full angle.

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

[0088] Optionally, in some embodiments, a preset steering assist curve is obtained by correcting an initial calibration curve according to 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 a preset steering assist curve according to the multiple product results.

[0089] Relevant technical personnel in this field can understand that the maximum value of the torque fluctuation is equivalent to the increase in the power assist generated by the steering gear, and the power assist curve is multiplied by the corresponding fluctuation ratio, that is, the increase in the power assist of the steering gear 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] The embodiment of the present application can obtain a preset steering assist curve by multiplying the initial calibration curve by the corresponding fluctuation ratio, and correcting the initial calibration 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 angular velocity to be calibrated, 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 formed into a preset steering assist curve.

[0091] Optionally, in some embodiments, after forming a preset steering assist curve according to multiple multiplication results, it also includes: simulating the electric power steering system based on the preset steering assist curve, and generating a fluctuation curve graph of the electric power steering system according to the simulation results; if the fluctuation rate of the electric power steering system calculated according to the fluctuation curve graph is less than or equal to a preset threshold value, then the preset steering assist curve is determined to be qualified.

[0092] It can be understood that in order to ensure that the preset steering assist curve obtained by correcting the initial calibration curve of the electric steering gear can effectively reduce the volatility of the electric power steering system, the embodiment of the present application can simulate the electric power steering system using the preset steering assist curve after obtaining the preset steering assist curve, and generate a volatility curve graph of the electric power steering system according to the simulation results, and calculate the volatility of the electric power steering system according to the volatility curve graph. If the calculated volatility of the electric power steering system is less than the preset threshold value, the preset steering assist curve is determined to be 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 steering assist system.

[0093] In addition, if the calculated fluctuation rate of the electric power steering system is greater than a preset threshold, the preset steering assist curve is determined to be unqualified, that is, controlling the electric power steering system based on the preset steering assist curve does not effectively improve 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 according to a plurality of multiplication results, the method further includes: performing zero position calibration on the electric steering gear based on the preset steering assist curve.

[0095] It is understandable that in order to improve the steering quality and make the driving direction of the wheels consistent with the actual driving direction of the vehicle, before the vehicle rolls off the assembly line, the embodiment of the present application can perform zero-position calibration on the electric steering gear based on a preset steering assist curve to prevent the vehicle from running off the assembly line.

[0096] In step S303, the electric power steering system is controlled to provide steering assistance to the current vehicle based on the target steering assistance 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, thereby improving the torque fluctuation caused by errors in the actual manufacturing and assembly process of the electric steering assist system, reducing the fluctuation range of the torque, and improving the driving comfort of the driver.

[0098] Therefore, the embodiment of the present application can continue to reduce the fluctuation range of the torque on the basis of the original initial calibration curve, avoid torque fluctuations caused by manufacturing and assembly errors, and optimize the driving experience.

[0099] In summary, the embodiment of the present application can add a logic in the electric steering controller, and can self-learn before the steering calibrates the steering wheel center position. The content of self-learning is as follows: 1. First, the electric steering has an initial calibration power curve data. Before the whole vehicle is offline for steering zero position calibration, the steering wheel is turned at a full angle, and the steering controller receives the first angular velocity and the second angular velocity monitored by the angle sensor, and calculates the angular velocity ratio of the two angle sensors at this time; 2. Then the data of the initial calibration power curve of the electric steering is multiplied by this ratio to form the final steering power curve data. The principle is that the maximum value of the torque fluctuation is equivalent to the increase in the power generated by the steering gear. The power curve is multiplied by the corresponding fluctuation ratio, that is, the increase in the power of the steering gear no longer requires a large input torque (driver's operating force), so that the torque balance will be achieved, and the purpose of reducing the torque fluctuation range will be achieved.

[0100] According to the control method of the electric power steering system proposed in the embodiment of the present application, an angular velocity sensor is installed under the steering wheel to obtain the angular velocity of the steering wheel, the steering wheel is turned at a full angle, the angular velocity ratio of the angular velocity of the electric steering gear and the angular velocity of the steering wheel is calculated, the initial calibration curve is corrected by the angular velocity ratio to obtain a preset steering assistance curve, and then the target steering assistance torque of the current vehicle is obtained according to the first angular velocity of the electric steering gear, the second angular velocity of the steering wheel and the preset steering assistance curve, and the electric power steering system is controlled to perform steering assistance on the current vehicle based on the target steering assistance torque. In this way, the problem that the actual torque fluctuation range is large due to manufacturing errors and assembly errors, and the driver's hand force will change nonlinearly when turning the steering wheel is solved, the torque fluctuation range can be reduced, and driving comfort can be improved.

[0101] Next, the control device of the electric power steering system proposed in the embodiment of the present application is described with reference to the accompanying drawings.

[0102] Figure 5 It is a block diagram of a control device of an electric power steering system according to an embodiment of the present 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 a first angular velocity of the electric steering gear by using a first angular velocity sensor, and to acquire a second angular velocity of the steering wheel by using a second angular velocity sensor.

[0105] The calculation module 200 is used to obtain the target steering assist torque of the current vehicle according to 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 steering gear.

[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 assistance torque.

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

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

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

[0110] The generating unit is used for taking the current steering assist torque as the target steering assist torque when the fluctuation rate is less than or equal to a preset threshold value.

[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 fluctuation rate is greater than a preset threshold.

[0113] The generating subunit is used to use the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque. Optionally, in some embodiments, before obtaining the target steering assist torque of the current vehicle according to the first angular velocity, the second angular velocity and the preset steering assist curve, the calculating module 200 further includes: an acquiring unit, a calculating unit and a generating unit.

[0114] Among them, the acquisition unit is used to rotate the steering wheel at a full angle, and use the second angular velocity sensor to obtain multiple first angular velocities to be calibrated of the steering wheel, and use the first angular velocity sensor to obtain multiple second angular velocities to be calibrated of the electric steering gear, wherein the multiple first angular velocities to be calibrated correspond one-to-one to 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, so as to obtain a plurality of angular velocity ratios.

[0116] The generating unit is used to correct the initial calibration curve according to a plurality of 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 subunit 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 the 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 form a preset steering assist curve according to the multiple product results.

[0120] Optionally, in some embodiments, after forming a preset steering assist curve according to a plurality of product results, the calculation subunit further includes: a calibration subcomponent.

[0121] Among them, the calibration sub-component is used to perform zero-position calibration on the electric steering gear based on a preset steering assist curve.

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

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

[0124] The determination sub-component is used to determine that the preset steering assist curve is qualified when the fluctuation rate of the electric power steering system calculated according to the fluctuation curve diagram is less than or equal to a preset threshold value.

[0125] It should be noted that the above explanation of the control method embodiment of the electric power steering system is also applicable to the control device of the electric power steering system of this embodiment, which will not be repeated here.

[0126] According to the control device of the electric power steering system proposed in the embodiment of the present application, an angular velocity sensor is installed under the steering wheel to obtain the angular velocity of the steering wheel, the steering wheel is turned at a full angle, the angular velocity ratio of the angular velocity of the electric steering gear and the angular velocity of the steering wheel is calculated, and the initial calibration curve is corrected by the angular velocity ratio to obtain a preset steering assistance curve, and then the target steering assistance torque of the current vehicle is obtained according to the first angular velocity of the electric steering gear, the second angular velocity of the steering wheel and the preset steering assistance curve, and the electric power steering system is controlled to perform steering assistance on the current vehicle based on the target steering assistance torque. In this way, the problem that the actual torque fluctuation range is large due to manufacturing errors and assembly errors, and the driver's hand force will change nonlinearly when turning the steering wheel is solved, the torque fluctuation range can be reduced, and driving comfort can be improved.

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

[0128] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0129] When the processor 602 executes the program, the control method of the electric power steering system provided in the above embodiment is implemented.

[0130] Furthermore, the vehicle also includes:

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

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

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

[0134] If the memory 601, the processor 602 and the communication interface 603 are implemented independently, the communication interface 603, the memory 601 and the processor 602 can be connected to each other through a bus and communicate with each other. 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 an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

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

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

[0137] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

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

[0139] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0140] It should be understood that the various parts of the present application can be implemented in hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0141] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0142] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A control method for an electric power steering system, characterized in that: A first angular velocity sensor is provided at the position of the electric steering input shaft of the vehicle, and a second angular velocity sensor is provided between the steering wheel and the steering transmission shaft of the vehicle, wherein the method comprises the following steps: Using the first angular velocity sensor to acquire a first angular velocity of the electric steering gear, and using the second angular velocity sensor to acquire a second angular velocity of the steering wheel; Obtaining a target steering assist torque of the current vehicle according to 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 steering gear; and The electric power steering system is controlled to provide steering assistance to the current vehicle based on the target steering assistance torque.

2. The method according to claim 1, characterized in that The step of obtaining a target steering assist torque of the current vehicle according to the first angular velocity, the second angular velocity and a preset steering assist curve includes: Based on the first angular velocity and the second angular velocity, matching and obtaining a current steering assist torque from the preset steering assist curve; Calculating a fluctuation rate of the electric power steering system based on the current steering assist torque, and determining whether the fluctuation rate is less than or equal to a preset threshold; If the fluctuation rate is less than or equal to the preset threshold, the current steering assist torque is used as the target steering assist torque.

3. The method according to claim 2, characterized in that After determining whether the volatility is less than or equal to the preset threshold, the method further includes: If the fluctuation rate is greater than the preset threshold, calculating a current angular velocity ratio of the first angular velocity to the second angular velocity; The product of the current steering assist torque and the current angular velocity ratio is used as the target steering assist torque.

4. The method according to claim 1 or 2, characterized in that: Before obtaining the target steering assist torque of the current vehicle according to the first angular velocity, the second angular velocity and the preset steering assist curve, the method further includes: Rotate the steering wheel at a full angle, use the second angular velocity sensor to obtain a plurality of first angular velocities to be calibrated of the steering wheel, and use the first angular velocity sensor to obtain a plurality of second angular velocities to be calibrated of the electric steering gear, wherein the plurality of first angular velocities to be calibrated correspond to the plurality of second angular velocities to be calibrated one by one; 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, to obtain a plurality of angular velocity ratios; The preset steering assist curve is obtained by correcting the initial calibration curve according to the multiple angular velocity ratios.

5. The method according to claim 4, characterized in that The step of correcting the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve includes: Based on the multiple first angular velocities to be calibrated, determining the data to be corrected corresponding to each of the first angular velocities to be calibrated in the initial calibration curve; 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 a plurality of product results, and the preset steering assist curve is formed according to the plurality of product results.

6. A control device for an electric power steering system, characterized in that: A first angular velocity sensor is provided at the position of the electric steering input shaft of the vehicle, and a second angular velocity sensor is provided between the steering wheel and the steering transmission shaft of the vehicle, wherein the device comprises: an acquisition module, configured to acquire a first angular velocity of the electric steering gear by using the first angular velocity sensor, and acquire a second angular velocity of the steering wheel by using the second angular velocity sensor; a calculation module, configured to obtain a target steering assist torque of the current vehicle according to 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 steering gear; 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 assistance torque.

7. The device according to claim 6, characterized in that The computing module comprises: a matching unit, configured to obtain a current steering assist torque by matching the preset steering assist curve based on the first angular velocity and the second angular velocity; a calculation unit, configured to calculate a fluctuation rate of the electric power steering system based on the current steering assist torque, and determine whether the fluctuation rate is less than or equal to a preset threshold; A generating unit is used to use the current steering assist torque as the target steering assist torque when the fluctuation rate is less than or equal to the preset threshold.

8. The device according to claim 7, characterized in that After determining whether the volatility is less than the preset threshold, the calculation unit further includes: A calculation subunit, configured to calculate a current angular velocity ratio of the first angular velocity to the second angular velocity when the fluctuation rate is greater than the preset threshold; A generating subunit is used to take the product of the current steering assist torque and the current angular velocity ratio as the target steering assist torque.

9. The device according to claim 6 or 7, characterized in that Before obtaining the target steering assist torque of the current vehicle according to the first angular velocity, the second angular velocity and the preset steering assist curve, the calculation module further includes: an acquisition unit, configured to rotate the steering wheel at a full angle, and acquire a plurality of first angular velocities to be calibrated of the steering wheel using the second angular velocity sensor, and acquire a plurality of second angular velocities to be calibrated of the electric steering gear using the first angular velocity sensor, wherein the plurality of first angular velocities to be calibrated correspond to the plurality of second angular velocities to be calibrated one by one; a calculation unit, configured to calculate a 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, to obtain a plurality of angular velocity ratios; A generating unit is used to correct the initial calibration curve according to the multiple angular velocity ratios to obtain the preset steering assist curve.

10. A vehicle, characterized in that: include: 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 the control method of the electric power steering system as described in any one of claims 1 to 5.

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