Frictional torque estimation method and device, electric power steering system and vehicle

Abstract

This application relates to a method and device for estimating frictional torque, an electric power steering system, and a vehicle. The method for estimating frictional torque includes: obtaining a basic frictional torque constant of the electric power steering system; obtaining a first functional relationship between the load torque, the input torque, the motor assist torque, and the basic frictional torque constant; when the electric power steering system is applied to a steering scenario, obtaining a second functional relationship between the frictional torque and the load torque; and obtaining a functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant based on the first functional relationship and the second functional relationship.

Description

Technical Field

[0001] This application relates to the technical field of vehicles, and in particular, to a method and device for estimating frictional torque, an electric power steering system, and a vehicle. Background Art

[0002] In the current EPS (Electrical Power Steering) assist system, due to the addition of components such as a speed reducer, the frictional torque increases. In order to improve the feel during steering, a compensation constant can be set based on the frictional torque and compensated during the steering process.

[0003] Obviously, under different working conditions, the frictional torque varies, and the existing compensation method is single, resulting in limited improvement in the steering feel experience. Summary of the Invention

[0004] This application provides a method, a device, and an electronic device to solve the deficiencies in the related art.

[0005] According to the first aspect of the embodiments of this application, a method for estimating frictional torque is provided. The estimation method includes:

[0006] Obtain the basic frictional torque constant of the electric power steering system;

[0007] Obtain the first functional relationship between the load torque, the input torque, the motor assist torque, and the basic frictional torque constant;

[0008] When the electric power steering system is applied to a steering scenario, obtain the second functional relationship between the frictional torque and the load torque;

[0009] Based on the first functional relationship and the second functional relationship, obtain the functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant.

[0010] Optionally, the obtaining of the basic frictional torque constant of the electric power steering system includes:

[0011] Obtain the frictional torque budget values under multiple preset load torque conditions, and the maximum torque difference between the multiple preset load torques is greater than or equal to 15 Nm;

[0012] Based on the multiple frictional torque budget values, obtain the basic frictional torque constant.

[0013] Optionally, the obtaining of the frictional torque budget values under multiple working conditions corresponding to multiple preset load torque values includes:

[0014] Control the full-angle rotation of the steering shaft of the electric power steering system based on a preset load torque and an input torque;

[0015] Taking the rotation angle of the steering shaft as the abscissa and the difference between the input torque and the preset load torque as the ordinate, plot the hysteresis curve of the frictional torque budget value;

[0016] Obtain the frictional torque budget value according to multiple critical values of the hysteresis curve.

[0017] Optionally, the obtaining the frictional torque budget value according to multiple critical values of the hysteresis curve includes:

[0018] Obtain the upper critical value and the lower critical value of the hysteresis curve;

[0019] Take half of the difference between the upper critical value and the lower critical value as the frictional torque budget value.

[0020] Optionally, the obtaining the first functional relationship between the load torque, the input torque, the motor assist torque, and the basic frictional torque constant includes:

[0021] Based on the system torque balance equation, substitute the basic frictional torque constant into the real-time frictional torque in the system torque balance equation to obtain the first functional relationship;

[0022] The system torque balance equation is as follows:

[0023] T load =T driver +T motor -sgn(ω sw )*T f

[0024]

[0025] where, T driver is the input torque;

[0026] T motor is the motor assist torque;

[0027] ω sw is the steering wheel rotation speed;

[0028] T f is the real-time frictional torque that needs to be overcome during the steering of the electric power steering system;

[0029] T load is the load torque of the real-time electric power steering system;

[0030] The first functional relationship is as follows:

[0031]

[0032] Among them, is the estimated load torque of the electric power steering system, and T f0 is the basic friction torque constant.

[0033] Optionally, obtaining the second functional relationship includes:

[0034] Taking the torque value of the preset load torque as the horizontal axis and the friction torque budget value as the vertical axis, plot a scatter plot between the friction torque budget value and the preset load torque;

[0035] Fit the above scatter plot to obtain the second functional relationship.

[0036] Optionally, the second functional relationship is:

[0037]

[0038] where K f is the friction torque load coefficient of the steering system;

[0039] K f,const is the friction torque constant of the steering system;

[0040] is the estimated friction torque.

[0041] Optionally, based on the first functional relationship and the second functional relationship, the functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant is obtained as follows:

[0042]

[0043] T motor =(i m *K m )*i ww

[0044] where K m is the torque constant of the assist motor;

[0045] i ww is the reduction ratio of the reducer of the electric power steering system;

[0046] i m is the assist current;

[0047] is the estimated friction torque.

[0048] According to the second aspect of the embodiments of the present disclosure, an estimation device for friction torque is provided. The estimation device includes:

[0049] The first acquisition module acquires the basic friction torque constant of the electric power steering system;

[0050] The second acquisition module acquires the first functional relationship among the load torque, the input torque, the motor assist torque, and the basic friction torque constant;

[0051] The third acquisition module acquires the second functional relationship between the friction torque and the load torque when the electric power steering system is applied to a steering scenario;

[0052] The fourth acquisition module acquires the functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant based on the first functional relationship and the second functional relationship.

[0053] Optionally, the first acquisition module includes:

[0054] The first acquisition sub-module acquires the friction torque budget values under multiple preset load torque conditions, and the maximum torque difference of the multiple preset load torques is greater than or equal to 15 Nm;

[0055] The first calculation sub-module obtains the basic friction torque constant according to the multiple friction torque budget values.

[0056] Optionally, the first acquisition sub-module includes:

[0057] The control unit controls the full-angle rotation of the steering shaft of the electric power steering system based on the preset load torque and the input torque;

[0058] The plotting unit plots the hysteresis curve of the friction torque budget value with the rotation angle of the steering shaft as the abscissa and the difference between the input torque and the preset load torque as the ordinate;

[0059] The acquisition unit acquires the friction torque budget value according to multiple critical values of the hysteresis curve.

[0060] Optionally, the acquisition unit includes:

[0061] The acquisition sub-unit acquires the upper critical value and the lower critical value of the hysteresis curve;

[0062] The calculation sub-unit takes half of the difference between the upper critical value and the lower critical value as the friction torque budget value.

[0063] Optionally, the second acquisition module includes:

[0064] The second calculation sub-module substitutes the basic friction torque constant into the real-time friction torque in the system torque balance equation based on the system torque balance equation to obtain the first functional relationship;

[0065] The system torque balance equation is as follows:

[0066] T load = T driver + T motor - sgn(ω sw ) * T f

[0067]

[0068] Wherein, T driver is the input torque;

[0069] T motor is the motor assist torque;

[0070] ω sw is the steering wheel rotation speed;

[0071] T f is the real-time frictional torque that needs to be overcome during the steering of the electric power steering system;

[0072] T load is the load torque of the real-time electric power steering system;

[0073] The first functional relationship is as follows:

[0074]

[0075] Wherein, is the estimated load torque of the electric power steering system, T f0 is the basic frictional torque constant.

[0076] Optionally, the third acquisition module includes:

[0077] A plotting sub-module, which plots a scatter plot between the frictional torque budget value and the preset load torque, with the torque value of the preset load torque as the horizontal axis and the frictional torque budget value as the vertical axis;

[0078] A fitting sub-module, which fits the above scatter plot to obtain the second functional relationship.

[0079] Optionally, the second functional relationship is:

[0080]

[0081] Wherein, K f is the load coefficient of the steering system frictional torque;

[0082] K f,const is the steering system frictional torque constant;

[0083] is the estimated frictional torque.

[0084] Optionally, the functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant is as follows:

[0085]

[0086] T motor = (i m * K m ) * i ww

[0087] where K m is the assist motor torque constant;

[0088] i ww is the reduction ratio of the reducer of the electric power steering system;

[0089] i m is the assist current;

[0090] is the estimated frictional torque.

[0091] According to the third aspect of the embodiments of the present application, an estimation test bench for frictional torque is provided, including a processor configured to implement the steps of the method in any of the above embodiments when executed.

[0092] According to the fourth aspect of the embodiments of the present application, an electric power steering system is provided, including a processor configured to implement the following functional relationship obtained in the method in any of the above embodiments:

[0093] The functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant.

[0094] According to the fourth aspect of the embodiments of the present application, a vehicle is provided, including the electric power steering system in any of the above embodiments.

[0095] According to the fifth aspect of the embodiments of the present application, a computer-readable storage medium is provided, on which computer instructions are stored, and when the instructions are executed by a processor, the steps of the method in any of the above embodiments are implemented.

[0096] The technical solutions provided by the embodiments of the present application may include the following beneficial effects:

[0097] As can be seen from the above embodiments, an algorithm for estimating the real-time frictional torque is provided in the present application, which is beneficial to estimating the frictional torque when the electric power steering system is applied to actual scenarios, and is conducive to performing different frictional torque compensations for different working conditions, thereby improving the user's operation feel and usage experience.

[0098] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0100] Figure 1 is a flowchart of a method for estimating a frictional torque shown according to an exemplary embodiment.

[0101] Figure 2 is a graph showing the curve relationship between the steering shaft angle and the frictional torque under a 0 Nm load condition shown according to an exemplary embodiment.

[0102] Figure 3 is a graph showing the curve relationship between the steering shaft angle and the frictional torque under a 20 Nm load condition shown according to an exemplary embodiment.

[0103] Figure 4 is a fitting schematic diagram between the frictional torque budget value and the load torque shown according to an exemplary embodiment.

[0104] Figure 5 is a flowchart of another method for estimating a frictional torque shown according to an exemplary embodiment.

[0105] Figure 6 is a comparison graph of the frictional torque measured in the laboratory and the frictional torque estimated by the present application under a 0 Nm load condition shown according to an exemplary embodiment.

[0106] Figure 7 is one of the block diagrams of an estimation device shown according to an exemplary embodiment.

[0107] Figure 8 is another block diagram of an estimation device shown according to an exemplary embodiment.

[0108] Figure 9 is a third block diagram of an estimation device shown according to an exemplary embodiment.

[0109] Figure 10 is a fourth block diagram of an estimation device shown according to an exemplary embodiment.

[0110] Figure 11 It is the fifth block diagram of an estimation device shown according to an exemplary embodiment.

[0111] Figure 12 It is the sixth block diagram of an estimation device shown according to an exemplary embodiment.

[0112] Figure 13 It is the block diagram of an estimation device for frictional torque shown according to an exemplary embodiment. Detailed implementation

[0113] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0114] The terms used in the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "the", and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0115] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0116] Figure 1 It is the flowchart of a method for estimating frictional torque shown according to an exemplary embodiment. As Figure 1 shown, this estimation method can be applied to a test bench or a computer. This estimation method includes the following steps:

[0117] In step 101, obtain the basic frictional torque constant of the electric power steering system.

[0118] In this embodiment, the basic frictional torque constant can be a constant obtained by synthesizing the electric power steering system under various working conditions.

[0119] In some embodiments, friction torque budget values under multiple preset load torque conditions can be obtained, and a basic friction torque constant can be obtained based on the multiple friction torque budget values. Among them, the maximum torque difference of the multiple preset load torques is greater than or equal to 15 Nm, so that the multiple preset load torque conditions can cover the easy steering scenario and the difficult steering scenario in the application of the electric power steering system. For example, friction torque budget values under two preset covering torque operations can be obtained. The torque value of one preset load torque can be equal to 0 Nm to simulate the steering scenario under no load, and the torque value of the other preset load torque can be equal to 20 Nm to simulate the steering scenario under an extremely large load. This can save computing resources and simplify the computing process. The average or median of the multiple friction torque budget values can be used as the basic friction torque constant, or the basic friction torque constant can also be obtained by referring to the weighted coefficient as the calculated value. This application does not limit this.

[0120] Regarding the acquisition of the friction torque budget value, in some embodiments, based on the preset load torque and the input torque, the steering shaft of the electric power steering system can be controlled to rotate through a full angle, and the rotation angle of the steering shaft can be used as the abscissa. The difference between the input torque and the preset load torque can be approximately equal to the friction torque in the electric power steering system, and this can be used as the ordinate to draw the hysteresis curve of the friction torque budget value; according to multiple critical values of the hysteresis curve, the friction torque budget value can be obtained. Among them, the input torque is to simulate the driver's operation when the electric power steering system is applied to devices such as vehicles. The rotation of the steering shaft can include a 360° full-angle rotation in the counterclockwise direction and a 360° full-angle rotation in the clockwise direction. The acquisition of the input torque can be obtained by collecting through a set sensor.

[0121] Taking the preset load torque as 0 Nm as an example, Figure 2 the hysteresis curve of the friction torque budget value under the 0 Nm load condition shown in the figure is obtained. In the case of the full-angle clockwise rotation and the full-angle counterclockwise rotation of the steering shaft, the difference between the input torque and the preset load torque will fluctuate with the angle, but it is basically within a rectangular frame. Therefore, Figure 2 the hysteresis curve shown by the red line in the figure can be drawn, and the friction torque budget value can be obtained according to the critical value or boundary value of the hysteresis curve. For example, the upper critical value and the lower critical value of the hysteresis curve can be obtained, and half of the difference between the upper critical value and the lower critical value can be used as the friction torque budget value under the 0 Nm load condition.

[0122] Taking the preset load torque as 20 Nm as an example, Figure 3The hysteresis curve of the frictional torque budget value under the 20 Nm load condition shown. When the steering shaft rotates clockwise through the full angle and counterclockwise through the full angle, the difference between the input torque and the preset load torque fluctuates with the angle, but is basically within a rectangular frame. Therefore, the hysteresis curve shown by the red line in Figure 3 can be plotted. The frictional torque budget value is obtained according to the critical value or boundary value of the hysteresis curve. For example, the upper critical value and the lower critical value of the hysteresis curve can be obtained, and the average of the upper critical value and the lower critical value is used as the frictional torque budget value under the 20 Nm load condition.

[0123] In step 102, a first functional relationship between the load torque, the input torque, the motor assist torque, and the basic frictional torque constant is obtained.

[0124] In this embodiment, the first functional relationship can be obtained based on the system balance equation when the driver operates the electric power steering system for steering. Among them, the load torque is the dependent variable, the input torque, the motor assist torque are the independent variables, and the basic frictional torque constant is a known value.

[0125] For example, during the steering process, the system torque balance equation is as follows:

[0126] T load = T driver + T motor - sgn(ω sw ) * T f

[0127]

[0128] Among them, T driver is the input torque;

[0129] T motor is the motor assist torque;

[0130] ω sw is the steering wheel rotation speed;

[0131] T f is the real-time frictional torque that needs to be overcome when the electric power steering system steers;

[0132] T load is the load torque of the real-time electric power steering system.

[0133] Based on the basic frictional torque constant obtained in step 101, since the change range of the frictional torque of the electric power steering system is usually within the range of 1 - 2 Nm, which is much smaller than the change range of the load torque, the basic frictional torque constant can be substituted as the real-time frictional torque in the system torque balance equation to obtain the first functional relationship as follows:

[0134]

[0135] Among them, is the estimated load torque of the electric power steering system;

[0136] T f0 is the basic friction torque constant.

[0137] In step 103, when the electric power steering system is applied to a steering scenario, a second functional relationship between the friction torque and the load torque is obtained.

[0138] In this embodiment, a discrete point graph between the friction torque budget value and the preset load torque can be plotted with the torque value of the preset load torque as the horizontal axis and the friction torque budget value as the vertical axis; the above discrete point graph is linearly fitted to obtain the second functional relationship.

[0139] For example, in step 101, taking the preset load torques of 0 Nm and 20 Nm as examples, the calculation of the friction torque budget value is adaptively described. In fact, based on the same method, the friction torque budget values under the preset load conditions of 2 Nm, 4 Nm, 6 Nm, 8 Nm, 10 Nm, 12 Nm, 14 Nm, 16 Nm, and 18 Nm can also be obtained, so as to plot Figure 4 the discrete point graph of the shown friction torque budget value and the preset load torque, and perform fitting on the discrete point graph to obtain the second functional relationship.

[0140] For example, as Figure 4 shown, linear fitting can be performed on the discrete point graph to obtain the second functional relationship. In some embodiments, the second functional relationship is as follows:

[0141]

[0142] where K f is the friction torque load coefficient of the steering system;

[0143] K f,const is the friction torque constant of the steering system;

[0144] is the estimated friction torque.

[0145] Of course, in other embodiments, other fitting methods can be performed on the discrete point graph, and the present application does not limit this.

[0146] In step 104, based on the first functional relationship and the second functional relationship, a functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant is obtained.

[0147] In this embodiment, the estimated frictional torque can replace the real-time frictional torque T load , that is, substituting the first functional relationship obtained in step 102 into the second functional relationship, so as to obtain the functional relationship between the frictional torque, the input torque, the motor assist torque and the basic frictional torque constant as follows:

[0148]

[0149] T motor =(i m *K m )*i ww

[0150] where K m is the torque constant of the assist motor;

[0151] i ww is the reduction ratio of the reducer of the electric power steering system;

[0152] i m is the assist current;

[0153] is the estimated frictional torque.

[0154] Among them, the estimated frictional torque is the dependent variable, the input torque and the assist current are the independent variables, and the others are constants. The assist current i m can be obtained from the assist motor controller of the electric power steering system, and the steering wheel rotation speed ω sw can be measured by a sensor.

[0155] When the electric power steering system is applied to an actual scenario, T driver the input torque, i m the assist current, ω sw the steering wheel rotation speed, i ww the reduction ratio of the reducer, K m the torque constant of the assist motor and T f0 the basic frictional torque constant can be used as the signal input for estimating the frictional torque, and the real-time frictional torque can be further calculated through the above functional relationship. Among them, the signals detected by the sensor can be subjected to amplitude limiting, filtering, and validity checking processing to provide correct, continuous, and smooth signals for the subsequent algorithm.

[0156] As can be seen from the above embodiments, the present application provides an algorithm for estimating the real-time frictional torque, which is beneficial to estimating the frictional torque when the electric power steering system is applied to an actual scenario, and is beneficial to performing different frictional torque compensations for different working conditions, thereby improving the user's operation feel and usage experience.

[0157] Based on the technical solution of this application, based on Figure 5 the embodiments shown below, the technical solution of this application will be described in detail.

[0158] In step 501, the friction torque budget values under multiple load torque conditions in the range of 0 Nm - 20 Nm are obtained.

[0159] In step 502, based on the friction torque budget values under the 0 Nm and 20 Nm load torque conditions, the basic friction torque constant is obtained.

[0160] In this embodiment, taking Figure 2 the friction torque hysteresis curve under the 0 Nm load torque condition in Figure 3 as an example, the friction torque budget value under the 0 Nm load torque condition is 1.05 Nm. Taking f0 the friction torque hysteresis curve under the 20 Nm load torque condition in

[0161] as an example, the friction torque budget value under the 20 Nm load torque condition is 2.45 Nm. Calculate the average value of the friction torque budget value under the 0 Nm load torque condition and the friction torque budget value under the 20 Nm load torque condition. This average value is 1.75 Nm. Therefore, the basic friction torque constant T

[0162] In step 503, the first functional relationship is obtained.

[0163]

[0164] T motor =(i m *K m )*i ww ;

[0165] Wherein, is the estimated load torque of the electric power steering system;

[0166] K m is the torque constant of the assist motor;

[0167] i ww is the reduction ratio of the reducer of the electric power steering system;

[0168] i m is the assist current.

[0169] Assume that the torque constant K m of the assist motor is 0.4402 Nm / A, and the reduction ratio i ww of the reducer is 18.5. Substitute the basic friction torque constant T f0 , and the first functional relationship obtained is:

[0170]

[0171] In step 504, a second functional relationship is obtained.

[0172] In this embodiment, it is assumed that based on Figure 4 the discrete point diagram in, linear fitting can be performed to obtain the load coefficient K of the friction torque of the steering system f to be 0.0675, and the friction torque constant K of the steering system f,const to be 1.0573 Nm. Based on this, the second functional relationship is obtained as:

[0173]

[0174] In step 505, the functional relationship between the friction torque, the input torque, the motor assist torque, and the basic friction torque constant is obtained.

[0175] In this embodiment, substituting the first functional relationship into the second functional relationship and simplifying, we get:

[0176]

[0177] Thus, the above formula can be written into the processor of the vehicle to which the electric power steering system belongs in the follow-up, so as to estimate the friction torque in the actual application scenario and use it as the real-time friction torque, and then perform friction torque compensation based on this to improve the operation feel.

[0178] To verify the accuracy of the functional relationship between the friction torque, the input torque, the motor assist torque, and the basic friction torque constant obtained in this application, as Figure 6 shown, a 10 Nm load torque condition is set, and the measured friction torque shown by the blue line is obtained. The red one is the friction torque estimated based on the estimation algorithm provided in this application. It can be seen that the difference between the two is basically within the range recognized by the engineering, verifying the effectiveness of the real-time friction torque estimation method provided in this application.

[0179] Corresponding to the foregoing embodiment of the estimation method, this application also provides an embodiment of an estimation device.

[0180] Figure 7 is one of the block diagrams of an estimation device shown according to an exemplary embodiment. Referring to Figure 7 , the device includes a first acquisition module 71, a second acquisition module 72, a third acquisition module 73, and a fourth acquisition module 74, where:

[0181] The first acquisition module 71 acquires the basic friction torque constant of the electric power steering system;

[0182] The second acquisition module 72 acquires a first functional relationship among the load torque, the input torque, the motor assist torque, and the basic friction torque constant;

[0183] The third acquisition module 73 acquires a second functional relationship between the friction torque and the load torque when the electric power steering system is applied to a steering scenario;

[0184] The fourth acquisition module 74 acquires a functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant based on the first functional relationship and the second functional relationship.

[0185] As Figure 8 shown, Figure 8 FIG. 2 is a second block diagram of an estimation device shown according to an exemplary embodiment. Based on the embodiment shown above, the first acquisition module 71 includes a first acquisition sub-module 711 and a first calculation sub-module 712, where: Figure 7 The first acquisition sub-module 711 acquires friction torque budget values under multiple preset load torque conditions, and the maximum torque difference of the multiple preset load torques is greater than or equal to 15 Nm;

[0186] The first calculation sub-module 712 obtains the basic friction torque constant according to the multiple friction torque budget values.

[0187]

[0188] As Figure 9 shown, Figure 9 Figure 8 FIG. 3 is a third block diagram of an estimation device shown according to an exemplary embodiment. Based on the embodiment shown above, the first acquisition sub-module 711 includes a control unit 713, a plotting unit 714, and an acquisition unit 715, where:

[0189] The control unit 713 controls the full-angle rotation of the steering shaft of the electric power steering system based on the preset load torque and the input torque;

[0190]

[0191] The plotting unit 714 plots a hysteresis curve of the friction torque budget value with the rotation angle of the steering shaft as the abscissa and the difference between the input torque and the preset load torque as the ordinate;

[0191] The acquisition unit 715 acquires the friction torque budget value according to multiple critical values of the hysteresis curve.

[0192] As Figure 10 shown, Figure 10 FIG. 4 is a fourth block diagram of an estimation device shown according to an exemplary embodiment. Based on the embodiment shown above, Figure 9Based on the illustrated embodiment, the acquisition unit 715 includes an acquisition subunit 716 and a calculation subunit 717, where:

[0193] The acquisition subunit 716 acquires the upper critical value and the lower critical value of the hysteresis curve;

[0194] The calculation subunit 717 takes half of the difference between the upper critical value and the lower critical value as the frictional torque budget value.

[0195] As Figure 11 shown, Figure 11 FIG. 5 is a fifth block diagram of an estimation device shown according to an exemplary embodiment, which is based on the foregoing Figure 7 illustrated embodiment. The second acquisition module 72 includes:

[0196] The second calculation sub-module 721, based on the system torque balance equation, substitutes the basic frictional torque constant into the real-time frictional torque in the system torque balance equation to obtain the first functional relationship;

[0197] The system torque balance equation is as follows:

[0198] T load = T driver + T motor - sgn(ω sw ) * T f

[0199]

[0200] where, T driver is the input torque;

[0201] T motor is the motor assist torque;

[0202] ω sw is the steering wheel rotation speed;

[0203] T f is the real-time frictional torque that needs to be overcome when the electric power steering system steers;

[0204] T load is the load torque of the electric power steering system;

[0205] The first functional relationship is as follows:

[0206]

[0207] where, is the estimated load torque of the electric power steering system;

[0208] T f0is the basic friction torque constant.

[0209] It should be noted that the structure of the second calculation sub-module 721 in the above Figure 11 shown device embodiment can also be included in any one of the Figures 8 - 10 device embodiments described above, and this application does not limit this.

[0210] As Figure 12 shown, Figure 12 is the sixth block diagram of an estimation device shown according to an exemplary embodiment. Based on the embodiment shown above Figure 7 , the third acquisition module 73 includes a drawing sub-module 731 and a fitting sub-module 732, where:

[0211] The drawing sub-module 731 plots a scatter plot between the friction torque budget value and the preset load torque, with the torque value of the preset load torque as the horizontal axis and the friction torque budget value as the vertical axis;

[0212] The fitting sub-module 732 fits the above scatter plot to obtain the second functional relationship.

[0213] It should be noted that the structures of the drawing sub-module 731, the fitting sub-module 732, and the fitting sub-module 732 in the above Figure 12 shown device embodiment can also be included in any one of the Figures 8 - 11 device embodiments described above, and this application does not limit this.

[0214] Optionally, the second functional relationship is:

[0215]

[0216] where K f is the friction torque load coefficient of the steering system;

[0217] K f,const is the friction torque constant of the steering system;

[0218] is the estimated friction torque.

[0219] Optionally, the functional relationship between the friction torque, the input torque, the motor assist torque, and the basic friction torque constant is as follows:

[0220]

[0221] T motor =(i m *K m )*i ww

[0222] Among them, K m is the torque constant of the assist motor;

[0223] i ww is the reduction ratio of the reducer of the electric power steering system;

[0224] i m is the assist current;

[0225] is the estimated frictional torque.

[0226] Regarding the device in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated herein.

[0227] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to the descriptions of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the present application. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0228] Correspondingly, the present application also provides an estimation test bench for frictional torque, including: a processor; a memory for storing instructions executable by the processor; wherein, the processor is configured to execute the steps described in any one of the foregoing methods. For example, the processor is configured to execute: obtaining the basic frictional torque constant of the electric power steering system; obtaining the first functional relationship between the load torque, the input torque, the motor assist torque, and the basic frictional torque constant; when the electric power steering system is applied to a steering scenario, obtaining the second functional relationship between the frictional torque and the load torque; based on the first functional relationship and the second functional relationship, obtaining the functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant.

[0229] Correspondingly, the present application also provides an electric power steering system, and the electric power steering system includes a processor, and the processor is configured to execute the following functional relationship obtained by the steps described in any one of the foregoing methods: the functional relationship between the frictional torque, the input torque, the motor assist torque, and the basic frictional torque constant.

[0230] The present application also provides a vehicle, which includes the electric power steering system described in any of the foregoing embodiments. The vehicle includes a memory and one or more programs, where the one or more programs are stored in the memory and configured to be executed by one or more processors. The one or more programs include instructions for performing the following operations: obtaining a basic friction torque constant of the electric power steering system; obtaining a first functional relationship between a load torque, an input torque, a motor assist torque, and the basic friction torque constant; when the electric power steering system is applied to a steering scenario, obtaining a second functional relationship between a friction torque and the load torque; and obtaining a functional relationship between the friction torque, the input torque, the motor assist torque, and the basic friction torque constant based on the first functional relationship and the second functional relationship.

[0231] Figure 13 FIG. 1300 is a block diagram of an apparatus 1300 for estimating a friction torque according to an exemplary embodiment. For example, the apparatus 1300 can be a mobile phone, a computer, a digital broadcast terminal, a messaging device, a game console, a tablet device, a medical device, a fitness device, a personal digital assistant, etc.

[0232] Referring Figure 13 , the apparatus 1300 may include one or more of the following components: a processing component 1302, a memory 1304, a power supply component 1306, a multimedia component 1308, an audio component 1310, an input / output (I / O) interface 1312, a sensor component 1314, and a communication component 1316.

[0233] The processing component 1302 generally controls the overall operation of the apparatus 1300, such as operations associated with display, telephone calls, data communications, camera operations, and recording operations. The processing component 1302 may include one or more processors 1320 to execute instructions to complete all or part of the steps of the above-described method. In addition, the processing component 1302 may include one or more modules to facilitate interaction between the processing component 1302 and other components. For example, the processing component 1302 may include a multimedia module to facilitate interaction between the multimedia component 1308 and the processing component 1302.

[0234] The memory 1304 is configured to store various types of data to support the operation of the device 1300. Examples of such data include instructions for any application or method operating on the device 1300, contact data, phone book data, messages, pictures, videos, and the like. The memory 1304 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disks, or optical disks.

[0235] The power supply component 1306 provides power to various components of the device 1300. The power supply component 1306 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power for the device 1300.

[0236] The multimedia component 1308 includes a screen that provides an output interface between the device 1300 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen can be implemented as a touch screen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors can not only sense the boundaries of touch or swipe actions but also detect the duration and pressure associated with the touch or swipe operation. In some embodiments, the multimedia component 1308 includes a front camera and / or a rear camera. When the device 1300 is in an operating mode, such as a shooting mode or a video mode, the front camera and / or the rear camera can receive external multimedia data. Each of the front camera and the rear camera can be a fixed optical lens system or have focal length and optical zoom capabilities.

[0237] The audio component 1310 is configured to output and / or input audio signals. For example, the audio component 1310 includes a microphone (MIC) that is configured to receive external audio signals when the device 1300 is in an operating mode, such as a call mode, a recording mode, and a voice estimation mode. The received audio signals can be further stored in the memory 1304 or transmitted via the communication component 1316. In some embodiments, the audio component 1310 further includes a speaker for outputting audio signals.

[0238] The I / O interface 1312 provides an interface between the processing component 1302 and a peripheral interface module, and the peripheral interface module can be a keyboard, a click wheel, buttons, etc. These buttons can include, but are not limited to: a home button, a volume button, a start button, and a lock button.

[0239] The sensor assembly 1314 includes one or more sensors for providing a status assessment of various aspects of the device 1300. For example, the sensor assembly 1314 can detect the on / off state of the device 1300, the relative positioning of components, such as the display and keypad of the device 1300. The sensor assembly 1314 can also detect a change in the position of the device 1300 or a component of the device 1300, the presence or absence of user contact with the device 1300, the orientation or acceleration / deceleration of the device 1300, and a change in the temperature of the device 1300. The sensor assembly 1314 can include a proximity sensor configured to detect the presence of nearby objects without any physical contact. The sensor assembly 1314 can also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, the sensor assembly 1314 can also include an acceleration sensor, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

[0240] The communication component 1316 is configured to facilitate communication between the device 1300 and other devices in a wired or wireless manner. The device 1300 can access a wireless network based on communication standards, such as WiFi, 2G or 3G, 4G LTE, 5G NR, or a combination thereof. In an exemplary embodiment, the communication component 1316 receives a broadcast signal or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 1316 further includes a near field communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on radio frequency identification (RFID) technology, infrared data association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0241] In an exemplary embodiment, the device 1300 can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components for performing the above-described method.

[0242] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 1304 including instructions, and the above instructions can be executed by a processor 1320 of the device 1300 to complete the above-described method. For example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0243] Other embodiments of the present application will be readily apparent to those skilled in the art upon consideration of the specification and practice of the disclosure herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only illustrative, and the true scope and spirit of the present application are pointed out by the following claims.

[0244] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A method for estimating friction torque, characterized in that: The estimation method includes: Get the basic friction torque constant of the electric power steering system; Obtaining a first functional relationship between the load torque and the input torque, the motor assist torque, and the basic friction torque constant; When the electric power steering system is applied to a steering scenario, obtaining a second functional relationship between the friction torque and the load torque; Based on the first functional relationship and the second functional relationship, the functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant is obtained as follows: T motor =(i m *K m )*i ww Among them, K m is the torque constant of the power assist motor; i ww The speed ratio of the reducer of the electric power steering system; i m For assisting current; is the estimated friction torque; T f0 is the basic friction torque constant; T driver is the input torque; T motor Provides assist torque for the motor; ω sw is the steering wheel speed; K f is the friction torque load coefficient of the steering system; K f,const is the friction torque constant of the steering system.

2. The estimation method according to claim 1, characterized in that: The obtaining of the basic friction torque constant of the electric power steering system comprises: Obtaining friction torque budget values ​​under multiple preset load torque conditions, wherein the maximum torque difference of the multiple preset load torques is greater than or equal to 15 Nm; The basic friction torque constant is obtained according to the multiple friction torque budget values.

3. The estimation method according to claim 2, characterized in that: The obtaining of the friction torque budget values ​​under various working conditions corresponding to the plurality of preset load torque values ​​includes: Based on a preset load torque and an input torque, controlling the steering shaft of the electric power steering system to rotate at a full angle; With the rotation angle of the steering shaft as the horizontal coordinate and the difference between the input torque and the preset load torque as the horizontal coordinate, a hysteresis curve of the friction torque budget value is drawn; The friction torque budget value is obtained according to a plurality of critical values ​​of the hysteresis curve.

4. The estimation method according to claim 3, characterized in that: The step of obtaining the friction torque budget value according to the multiple critical values ​​of the hysteresis curve includes: Get the upper and lower critical values ​​of the hysteresis curve; A half of the difference between the upper threshold value and the lower threshold value is used as the friction torque budget value.

5. The estimation method according to claim 1, characterized in that: The first functional relationship between the load torque and the input torque, the motor assist torque, and the basic friction torque constant is obtained as follows: Based on the system torque balance equation, the basic friction torque constant is substituted into the real-time friction torque in the system torque balance equation to obtain the first functional relationship; The system torque balance equation is as follows: T load =T driver +T motor -sgn(ω sw )*T f T f It is the real-time friction torque that the electric power steering system needs to overcome when steering; The first functional relationship is as follows: in, is the estimated load torque of the electric power steering system.

6. The estimation method according to claim 2, characterized in that: Obtaining the second functional relationship includes: With the torque value of the preset load torque as the horizontal axis and the friction torque budget value as the vertical axis, a discrete point diagram between the friction torque budget value and the preset load torque is drawn; The above discrete point graph is fitted to obtain the second functional relationship.

7. The estimation method according to claim 6, characterized in that: The second functional relationship is:

8. A friction torque estimation device, characterized in that: The estimation device comprises: A first acquisition module is used to acquire a basic friction torque constant of the electric power steering system; A second acquisition module is used to acquire a first functional relationship between the load torque and the input torque, the motor assist torque, and the basic friction torque constant; a third acquisition module, for acquiring a second functional relationship between the friction torque and the load torque when the electric power steering system is applied to a steering scenario; The fourth acquisition module acquires the functional relationship between the friction torque and the input torque, the motor assist torque, and the basic friction torque constant based on the first functional relationship and the second functional relationship as follows: T motor =(i m *K m )*i ww Among them, K m is the torque constant of the power assist motor; i ww The speed ratio of the reducer of the electric power steering system; i m For assisting current; is the estimated friction torque; T f0 is the basic friction torque constant; T driver is the input torque; T motor Provides assist torque for the motor; ω sw is the steering wheel speed; K f is the friction torque load coefficient of the steering system; K f,const is the friction torque constant of the steering system.

9. The estimation device according to claim 8, characterized in that The first acquisition module includes: A first acquisition submodule is used to acquire a friction torque budget value under a plurality of preset load torque conditions, wherein a maximum torque difference of the plurality of preset load torques is greater than or equal to 15 Nm; The first calculation submodule obtains the basic friction torque constant according to the multiple friction torque budget values.

10. The estimation device according to claim 9, characterized in that The first acquisition submodule includes: A control unit, which controls the steering shaft of the electric power steering system to rotate at a full angle based on a preset load torque and an input torque; A drawing unit, which draws a hysteresis curve of the friction torque budget value with the rotation angle of the steering shaft as the horizontal coordinate and the difference between the input torque and the preset load torque as the horizontal coordinate; An acquisition unit is configured to acquire the friction torque budget value according to a plurality of critical values ​​of the hysteresis curve.

11. The estimation device according to claim 10, characterized in that The acquisition unit comprises: Obtain the subunit, and obtain the upper critical value and the lower critical value of the hysteresis curve; The calculation subunit uses half of the difference between the upper critical value and the lower critical value as the friction torque budget value.

12. The estimation device according to claim 8, characterized in that The second acquisition module includes: A second calculation submodule, based on a system torque balance equation, substitutes the basic friction torque constant into the real-time friction torque in the system torque balance equation to obtain the first functional relationship; The system torque balance equation is as follows: T load =T driver +T motor -sgn(ω sw )*T f Wherein, T is the real-time friction torque that the electric power steering system needs to overcome when steering; The first functional relationship is as follows: in, is the estimated load torque of the electric power steering system.

13. The estimation device according to claim 9, characterized in that The third acquisition module includes: A drawing submodule, with the torque value of the preset load torque as the horizontal axis and the friction torque budget value as the vertical axis, draws a discrete point diagram between the friction torque budget value and the preset load torque; The fitting submodule fits the above discrete point graph to obtain the second functional relationship.

14. The estimation device according to claim 13, characterized in that The second functional relationship is: Among them, K f is the friction torque load coefficient of the steering system; K f,const is the friction torque constant of the steering system; is the estimated friction torque.

15. A friction torque estimation test bench, characterized in that: The method comprises a processor configured to implement the steps of the method according to any one of claims 1 to 8 when executed.

16. An electric power steering system, characterized in that: The method comprises a processor configured to execute the following functional relationship obtained by the method according to any one of claims 1 to 7: The functional relationship between the friction torque, the input torque, the motor assist torque and the basic friction torque constant is as follows: T motor =(i m *K m )*i ww Among them, K m is the torque constant of the power assist motor; i ww The speed ratio of the reducer of the electric power steering system; i m For assisting current; is the estimated friction torque; T f0 is the basic friction torque constant; T driver is the input torque; T motor Provides assist torque for the motor; ω sw is the steering wheel speed; K f is the friction torque load coefficient of the steering system; K f,const is the friction torque constant of the steering system.

17. A vehicle, characterized in that: Comprising the electric power steering system as claimed in claim 16.

18. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the instruction is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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