An electric power steering control method, electronic control unit and system

Abstract

The application discloses an electric power steering control method, an electronic control unit and a system, which are used for providing more matched steering assist torque for a driver from the real demand of the driver. The method comprises the following steps: acquiring a torque signal on a steering wheel of a vehicle and a vehicle speed signal of the vehicle; determining an initial steering assist torque of the vehicle according to the torque signal and the vehicle speed signal; determining a plurality of correction coefficients, wherein the plurality of correction coefficients comprise at least one of a road condition coefficient alpha and a driving habit coefficient beta, the size of the road condition coefficient alpha depends on the current driving road condition of the vehicle, and the size of the driving habit coefficient beta depends on the driving habit of the driver; and correcting the initial steering assist torque according to the plurality of correction coefficients to obtain a final steering assist torque of the vehicle.

Description

Technical Field

[0001] This invention relates to the field of automotive electronics technology, and more specifically, to an electric power steering control method, electronic control unit, and system. Background Technology

[0002] EPS (Electric Power Steering System) refers to a system that, based on a traditional mechanical steering system, uses an ECU (Electronic Control Unit) to control the car's electric motor to generate steering assist torque of corresponding magnitude and direction, based on torque signals from the steering wheel and vehicle speed signals. This provides auxiliary power to assist the driver in steering operations.

[0003] Currently, the amount of steering assist torque that should be generated under given torque and vehicle speed signals mainly relies on the subjective evaluation of the OEM's driving performance evaluation team, which lacks specificity for the differentiated needs of users in actual driving scenarios (such as differentiated needs in complex and ever-changing driving scenarios, differentiated needs of different driving groups, etc.). Summary of the Invention

[0004] In view of this, the present invention provides an electric power steering control method, an electronic control unit, and a system to provide a more suitable steering assist torque for the driver based on the driver's actual needs.

[0005] An electric power steering control method includes:

[0006] Acquire the torque signal from the car's steering wheel and the vehicle's speed signal;

[0007] The initial steering assist torque of the vehicle is determined based on the torque signal and the vehicle speed signal;

[0008] Several correction coefficients are determined, including at least one of the two correction coefficients: road condition coefficient α and driving habit coefficient β; the magnitude of road condition coefficient α depends on the current road conditions of the vehicle, and the magnitude of driving habit coefficient β depends on the driver's driving habits.

[0009] The initial steering assist torque is corrected according to the aforementioned correction coefficients to obtain the final steering assist torque of the vehicle.

[0010] Optionally, the step of correcting the initial steering assist torque according to the plurality of correction coefficients to obtain the final steering assist torque of the vehicle includes:

[0011] When the plurality of correction coefficients equals one correction coefficient, the initial steering assist torque is multiplied by the one correction coefficient, and the result of the multiplication is taken as the final steering assist torque of the vehicle.

[0012] When the plurality of correction coefficients are multiple correction coefficients, the initial steering assist torque is multiplied by the product of the plurality of correction coefficients, and the result of the multiplication is taken as the final steering assist torque of the vehicle.

[0013] Optionally, the current road conditions of the vehicle include: the degree of congestion on the current road segment;

[0014] Correspondingly, the road condition coefficient α is determined, including:

[0015] Obtain the congestion coefficient of the current road segment provided by the vehicle navigation system, and determine the corresponding road condition coefficient α under the current congestion coefficient by querying the pre-established correspondence between the congestion coefficient and the road condition coefficient α.

[0016] Optionally, determine the driving habit coefficient β, including:

[0017] The torque variation coefficient λ is calculated based on the torque signal; the torque variation coefficient λ is a physical quantity characterizing the rate of change of the torque signal.

[0018] Query the correspondence between the torque variation coefficient λ and the driving habit coefficient β at different vehicle speeds to obtain the driving habit coefficient β corresponding to the current vehicle speed and torque variation coefficient λ.

[0019] Optionally, the different vehicle speed ranges are divided into three segments: low speed range, medium speed range, and high speed range.

[0020] Optionally, if the activation condition corresponding to any correction factor is not met, the correction factor will be assigned the value of 1.

[0021] Optionally, after correcting the initial steering assist torque according to the plurality of correction coefficients, the method further includes:

[0022] The sum of multiple compensation torques is calculated, and the final compensation value is obtained after limiting the sum of the compensation torques.

[0023] The final compensation value is superimposed on the first correction value to obtain the final steering assist torque of the vehicle; the first correction value refers to the steering assist torque value obtained after correcting the initial steering assist torque according to the plurality of correction coefficients.

[0024] Optionally, after adding the final compensation value to the first correction value, the method further includes:

[0025] Calculate the active return-to-center torque and add it to the second correction value to obtain the final steering assist torque of the car.

[0026] The second correction value refers to the sum of the first correction value and the final compensation value.

[0027] An electronic control unit includes a processor and a memory, the memory storing a program that, when executed by the processor, implements any of the electric power steering control methods disclosed above.

[0028] An electric power steering system includes: any of the electronic control units disclosed above.

[0029] As can be seen from the above technical solution, the present invention incorporates the driver's differentiated needs for steering assist torque in the actual driving environment on the basis of traditional steering assist torque calculation, such as differentiated needs under complex and ever-changing driving scenarios and / or differentiated needs of different driving groups, thereby providing the driver with a more suitable steering assist torque. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart of an electric power steering control method disclosed in an embodiment of the present invention;

[0032] Figure 2 This is a diagram showing the correspondence between the congestion coefficient η and the road condition coefficient α, as disclosed in an embodiment of the present invention.

[0033] Figure 3 This is a diagram showing the correspondence between the torque variation coefficient λ and the driving habit coefficient β at a certain vehicle speed range, as disclosed in an embodiment of the present invention.

[0034] Figure 4 This is a flowchart of another electric power steering control method disclosed in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of an ECU structure disclosed in an embodiment of the present invention. Detailed Implementation

[0036] For the sake of clarity and reference, the technical terms, abbreviations, or acronyms used below are summarized as follows:

[0037] EPS: Electric Power Steering System;

[0038] ECU: Electronic Control Unit;

[0039] ABS: Anti-lock Braking System;

[0040] TAS: Torque Angle Sensor;

[0041] CAN: Controller Area Network;

[0042] N·m: Newton-meter;

[0043] km / h: kilometers per hour.

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] See Figure 1 This invention discloses an electric power steering control method, comprising:

[0046] Step S01: Obtain the torque signal from the car steering wheel and the vehicle speed signal, then proceed to step S02.

[0047] Step S02: Determine the initial steering assist torque of the vehicle based on the torque signal and the vehicle speed signal, and then proceed to step S03.

[0048] Specifically, when the driver operates the steering wheel to steer, the EPS system acquires the torque signal from the steering wheel and the vehicle speed signal and sends them to the ECU in the EPS system. The ECU queries a pre-built correspondence between torque, vehicle speed, and steering assist coefficient (hereinafter referred to as "correspondence 1") to obtain the steering assist coefficient corresponding to the current torque and vehicle speed signals, and then calculates the steering assist torque based on the current steering assist coefficient. However, this embodiment of the invention requires that the ECU does not directly use the steering assist torque obtained based on "correspondence 1" as the steering assist torque that the car's electric motor needs to output, but only as an initial steering assist torque. It needs to be corrected on this basis, and then a command is sent to the electric motor controller based on the corrected steering assist torque to make the electric motor output a steering assist torque of the corresponding magnitude and direction, thereby generating auxiliary power to assist the driver in steering operations.

[0049] The vehicle speed signal is typically collected by the ABS system and transmitted to the CAN bus. Multiple automotive electronic control systems, including the EPS system, can directly obtain this speed signal from the CAN bus. The torque signal on the steering wheel can be directly measured by the TAS sensor in the EPS system. The torque in "Correspondence 1" is generally calculated by the ECU based on the torque signal from the steering wheel using a phase compensation algorithm.

[0050] "Correspondence 1" can be represented by a three-dimensional curve graph or a three-dimensional table. When represented as a three-dimensional table, the corresponding steering assist coefficient is obtained by querying "Correspondence 1," which is achieved through a lookup table method or a lookup table interpolation method. The lookup table method involves compiling pre-calculated or measured data into a table in a specific order, and then directly looking up the result based on the input parameters. The lookup table interpolation method is a binary search method that compares the search keyword with the maximum and minimum record keywords in the lookup table. Table 1 below provides an example of "Correspondence 1," where the unit of torque is N·m and the unit of vehicle speed is km / h.

[0051] Table 1 - Correspondence between torque, vehicle speed, and steering assist coefficient

[0052]

[0053] Based on Table 1, when the vehicle speed is 8 km / h and the torque is 0.25 Nm, the steering assist coefficient obtained by looking up the table is 61; when the vehicle speed is 40 km / h and the torque is 1 Nm, the steering assist coefficient obtained by looking up the table is 148; when the vehicle speed is 4 km / h and the torque is 0.375 Nm, the steering assist coefficient calculated by interpolation using the table lookup method is [(198+61) / 2+(331+135) / 2] / 2=206.4. Of course, the currently used table lookup interpolation formula is only an example and is not a limitation.

[0054] Step S03: Determine several correction coefficients, and then proceed to step S04.

[0055] The selection of the plurality of correction coefficients takes into account the differentiated needs of drivers for steering assist torque in actual driving environments. In one example, the plurality of correction coefficients includes at least one of two correction coefficients: road condition coefficient α and driving habit coefficient β; the magnitude of road condition coefficient α depends on the current road conditions of the vehicle, and the magnitude of driving habit coefficient β depends on the driver's driving habits.

[0056] Step S04: Correct the initial steering assist torque according to the aforementioned correction coefficients to obtain the final steering assist torque of the vehicle, thus ending this round of control.

[0057] Specifically, the steering assist coefficient is a physical quantity characterizing the steering assist torque. Therefore, "correspondence 1" is essentially the correspondence between torque, vehicle speed, and steering assist torque. Currently, the correspondence between torque, vehicle speed, and steering assist torque mainly relies on the subjective evaluation of the OEM's driving performance evaluation team, without incorporating the differentiated needs of drivers for steering assist torque in actual driving environments, such as the differentiated needs under complex and varied driving scenarios, and the differentiated needs of different driving groups. To obtain a steering assist torque that better matches the driver's needs, this embodiment of the invention takes into account the differentiated needs of the driver in n aspects (n is a positive integer) and corrects the steering assist torque obtained according to "correspondence 1". Specifically, n correction coefficients are set based on the differentiated needs of the driver in n aspects. When n equals 1, the initial steering assist torque is multiplied by this correction coefficient to obtain the corrected steering assist torque; when n is greater than 1, the initial steering assist torque is multiplied by the product of the n correction coefficients to obtain the corrected steering assist torque. The larger n is, the more diverse needs of the driver are incorporated into the corrected steering assist torque, and the higher the degree of matching between the corrected steering assist torque and the driver's needs. However, this will also lead to higher calculation complexity, so a compromise value needs to be chosen when setting the size of n.

[0058] The initial steering assist torque is denoted as Torque_initial, and the corrected steering assist torque, which is the final steering assist torque mentioned in step S04, is denoted as Torque_ad. In one example, n=2, and two correction coefficients, road condition coefficient α and driving habit coefficient β, are introduced. In this case, Torque_ad = Torque_initial × α × β. The magnitude of the road condition coefficient α depends on the current road conditions of the vehicle. The introduction of the road condition coefficient α can meet the differentiated needs for steering assist torque in complex and ever-changing driving scenarios. The magnitude of the driving habit coefficient β depends on the driver's driving habits. The introduction of the driving habit coefficient β can meet the differentiated needs for steering assist torque of different driving groups.

[0059] The current road conditions of the vehicle may include the congestion level of the current road segment. The method for determining the road condition coefficient α includes: obtaining the congestion coefficient η of the current road segment provided by the vehicle navigation system; and obtaining the road condition coefficient α corresponding to the current congestion coefficient η by querying a pre-established correspondence between the congestion coefficient η and the road condition coefficient α (hereinafter referred to as "correspondence relationship 2"). "Correspondence relationship 2" can be represented in the form of a two-dimensional table, as shown in Table 2 below. The road condition coefficient α can be determined using a lookup table method or a lookup table interpolation method.

[0060] Table 2 - Correspondence between congestion coefficient η and road condition coefficient α

[0061] α <![CDATA[α1]]> <![CDATA[α2]]> <![CDATA[α3]]> …… <![CDATA[α x ]]>

[0062] Table 2 lists the road condition coefficient α values ​​corresponding to x congestion coefficients η, where x is an integer greater than 1. The more congested the current road segment (i.e., the larger the congestion coefficient η), the more frequently drivers change lanes. In this case, a "lighter" steering feel is desired, meaning the car needs to respond more sensitively to steering input. Therefore, the steering assist torque should be increased, and α should be set > 1. However, considering the mechanical load-bearing capacity of the car's steering system, the steering assist torque should not be too high. Therefore, the road condition coefficient α needs an upper limit. This invention recommends setting it to 1 < α ≤ 1.5, for example... Figure 2 The diagram shows the relationship between the congestion coefficient η and the road condition coefficient α.

[0063] Of course, the current road conditions of the vehicle can also take into account other factors that affect the number of times the vehicle turns, such as the degree of road surface damage, in order to improve the consistency between the road condition coefficient α and the actual road conditions.

[0064] A method for determining the value of driving habit coefficient β, comprising: calculating a torque variation coefficient λ according to a torque signal of a vehicle, wherein the torque variation coefficient λ is a physical quantity characterizing a change rate of the torque signal; querying a corresponding relationship between the torque variation coefficient λ and the driving habit coefficient β under different vehicle speed segments, to obtain the driving habit coefficient β corresponding to a current vehicle speed segment and the torque variation coefficient λ.

[0065] Specifically, when a vehicle is driving at a high speed, the vehicle is more sensitive to the rotation input of the steering wheel, and the vehicle will have an obvious steering sign when the steering wheel is rotated slightly. At this time, if the steering assist torque is too large, it is difficult to control the direction of the vehicle, which will affect the driving stability of the vehicle. When the vehicle speed is low, it is more labor-saving to operate the vehicle if the steering wheel is lighter. Therefore, the steering wheel should be "light" when driving at a low speed and "heavy" when driving at a high speed. Based on this, the embodiment of the present invention divides the vehicle speed into a plurality of vehicle speed segments, and sets a corresponding relationship between the torque variation coefficient λ and the driving habit coefficient β for each vehicle speed segment (hereinafter referred to as "corresponding relationship 3").

[0066] Sampling is performed y times at a fixed sampling frequency within one sampling period T (the sampling frequency is 1 second for example), and y torque signals t1, t2, ..., t are obtained sequentially y , where y is an integer greater than 1, and the calculation formula of the torque variation coefficient λ is as follows:

[0067]

[0068] In an example, the vehicle speed can be divided into three segments, which are a low vehicle speed segment, a medium vehicle speed segment and a high vehicle speed segment respectively (the discrimination of the vehicle speed segment can be performed by a hysteresis comparison method, that is, the low vehicle speed segment is set to 0~V1, the medium vehicle speed segment is set to V2~V3, and the high vehicle speed segment is set to V4~V5, where V1<V2<V3<V4<V5. When the vehicle speed is lower than or equal to V1, it is determined that the vehicle is in the low vehicle speed segment; when the vehicle speed is not lower than V2 and not higher than V3, it is determined that the vehicle is in the medium vehicle speed segment; when the vehicle speed is not lower than V4, it is determined that the vehicle is in the high vehicle speed segment; when the vehicle speed is higher than V1 and lower than V2, or higher than V3 and lower than V4, it is determined that the vehicle is still in the previous vehicle speed segment. The boundary values of the vehicle speed segments can be calibrated according to actual conditions. In an example, V1=32km / h, V2=40km / h, V3=72km / h, V4=80km / h, V5=200km / h can be set, but the invention is not limited thereto), which are respectively defined as V L , V M , V H , the "corresponding relationship 3" under different vehicle speed segments can be embodied in the form of a three-dimensional table, as shown in Table 3 below, and the driving habit coefficient β can be determined by a table lookup method or a table lookup interpolation method at this time.

[0069] Table 3 - Corresponding relationship table between torque variation coefficient λ and driving habit coefficient β under different vehicle speed segments

[0070]

[0071] Table 3 lists the values ​​of the driving habit coefficient β corresponding to the z torque variation coefficients λ at each vehicle speed range, where z is an integer greater than 1. Generally, 0 < β ≤ 1.5 is sufficient. The correspondence between the torque variation coefficient λ and the driving habit coefficient β at a certain vehicle speed range is shown in the figure below. Figure 3 As shown.

[0072] In summary, the embodiments of the present invention, based on traditional steering assist torque calculation, incorporate the differentiated needs of drivers for steering assist torque in actual driving environments, such as differentiated needs under complex and ever-changing driving scenarios and / or differentiated needs of different driving groups, so that the steering assist torque output by the electric motor is closer to the actual needs of the driver, bringing the driver a more comfortable and advanced steering assist feel.

[0073] Optionally, based on any of the above-disclosed embodiments, when the activation condition corresponding to any correction coefficient is not met, the correction coefficient is assigned a value of 1.

[0074] Specifically, the real-time value of any correction coefficient is determined only when the activation condition corresponding to that correction coefficient is met; otherwise, the correction coefficient is deemed invalid and assigned a value of 1. Taking the current road condition of the vehicle as the congestion level of the current driving segment as an example, if there is no congestion in the current driving segment, the activation condition of the road condition coefficient α is not met, and the road condition coefficient α is assigned a value of 1. Taking the driving habit coefficient β as another example, when the torque change coefficient λ exceeds the preset range, the activation condition of the driving habit coefficient β is not met, and the driving habit coefficient β is assigned a value of 1.

[0075] Optionally, based on any of the above-disclosed embodiments, the present invention further modifies the corrected steering assist torque Torque_ad by: calculating the sum of multiple compensation torques Tsum, performing limit processing on the sum of compensation torques Tsum to obtain the final compensation value Torque_comp, and superimposing it on the corrected steering assist torque Torque_ad as the final steering assist torque of the vehicle.

[0076] Specifically, Tsum is the sum of various compensation torques calculated internally by the EPS system (such as damping compensation Tor_damp_comp, friction compensation Tor_fric_comp, inertia compensation Tor_iner_comp, etc.). In one example, Tsum can be set to Tor_damp_comp + Tor_fric_comp + Tor_iner_comp. The calculation methods for each compensation torque are existing technologies and will not be elaborated upon in this article.

[0077] To avoid overcompensation, the sum of the compensation torques, Tsum, needs to be limited. Specifically, the compensation torque limit is set to Tlimit, and the final compensation value is Torque_comp. When Tlimit ≥ Tsum, Torque_comp = Tsum; when Tlimit < Tsum, Torque_comp = Tlimit.

[0078] Optionally, based on any of the embodiments disclosed above, the present invention further modifies the corrected steering assist torque Torque_ad, specifically as follows:

[0079] Calculate the active self-centering torque Torque_ar, and superimpose it onto the corrected steering assist torque Torque_ad to obtain the final steering assist torque of the car.

[0080] Preferably, the corrected steering assist torque Torque_ad, the final compensation value Torque_comp, and the active self-centering torque Torque_ar are superimposed to obtain the steering assist torque Output_tourqe_final, which is used as the vehicle's final steering assist torque. That is, Output_tourqe_final = Torque_ad + Torque_comp + Torque_ar. The corresponding electric power steering control method is as follows: Figure 4 As shown, it includes:

[0081] Step S11: Obtain the torque signal from the car steering wheel and the vehicle speed signal, then proceed to step S12.

[0082] Step S12: Determine the initial steering assist torque of the vehicle based on the torque signal and the vehicle speed signal, and then proceed to step S13.

[0083] Step S13: Determine several correction coefficients, and then proceed to step S14.

[0084] The plurality of correction coefficients include at least one of the two correction coefficients: road condition coefficient α and driving habit coefficient β; the magnitude of road condition coefficient α depends on the current road conditions of the vehicle, and the magnitude of driving habit coefficient β depends on the driver's driving habits.

[0085] Step S14: Correct the initial steering assist torque according to the several correction coefficients to obtain the corrected steering assist torque Torque_ad, and then proceed to step S15.

[0086] Step S15: Calculate the sum of multiple compensation torques Tsum, apply a limit to Tsum to obtain the final compensation value Torque_comp, and then proceed to step S16.

[0087] Step S16: Calculate the active return-to-center torque Torque_ar, then proceed to step S17.

[0088] The execution order of steps S15 and S16 can be interchanged.

[0089] Step S17: Calculate Output_tourqe_final = Torque_ad + Torque_comp + Torque_ar, and use Output_tourqe_final as the final steering assist torque of the car. This completes the current round of control.

[0090] Corresponding to the above method embodiments, this invention also discloses an ECU, such as... Figure 5 As shown, it includes: a processor and a memory, wherein the memory stores a program that, when executed by the processor, implements any of the electric power steering control methods disclosed above.

[0091] Furthermore, embodiments of the present invention also disclose an EPS system, including any of the ECUs disclosed above.

[0092] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the ECU and EPS systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to in the method section.

[0093] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar but different objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0094] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0095] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0096] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of the invention. Therefore, the embodiments of the invention are not to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electric power steering control method, characterized in that, include: Acquire the torque signal from the car's steering wheel and the vehicle's speed signal; The initial steering assist torque of the vehicle is determined based on the torque signal and the vehicle speed signal; Several correction coefficients are determined, including at least one of the two correction coefficients: road condition coefficient α and driving habit coefficient β; the magnitude of road condition coefficient α depends on the current road conditions of the vehicle, including the congestion level of the current road segment, and the magnitude of driving habit coefficient β depends on the driver's driving habits. The initial steering assist torque is corrected according to the plurality of correction coefficients to obtain the final steering assist torque of the vehicle, including: when the plurality of correction coefficients is a single correction coefficient, multiplying the initial steering assist torque by the single correction coefficient, and using the result of the multiplication as the final steering assist torque of the vehicle; when the plurality of correction coefficients is a plurality of correction coefficients, multiplying the initial steering assist torque by the product of the plurality of correction coefficients, and using the result of the multiplication as the final steering assist torque of the vehicle. Determining the road condition coefficient α includes: obtaining the congestion coefficient of the current road segment of the vehicle provided by the vehicle navigation system, and determining the corresponding road condition coefficient α under the current congestion coefficient by querying the pre-established correspondence between the congestion coefficient and the road condition coefficient α. Determining the driving habit coefficient β includes: calculating the torque change coefficient λ based on the torque signal; the torque change coefficient λ is a physical quantity characterizing the rate of change of the torque signal; querying the correspondence between the torque change coefficient λ and the driving habit coefficient β under different vehicle speed segments to obtain the driving habit coefficient β corresponding to the current vehicle speed segment and the torque change coefficient λ.

2. The electric power steering control method according to claim 1, characterized in that, The different speed ranges are divided into three segments: low speed range, medium speed range, and high speed range.

3. The electric power steering control method according to claim 1 or 2, characterized in that, If the activation condition corresponding to any correction factor is not met, the correction factor will be assigned the value of 1.

4. The electric power steering control method according to claim 1 or 2, characterized in that, After correcting the initial steering assist torque according to the plurality of correction coefficients, the method further includes: The sum of multiple compensation torques is calculated, and the final compensation value is obtained after limiting the sum of the compensation torques. The final compensation value is superimposed on the first correction value to obtain the final steering assist torque of the vehicle; the first correction value refers to the steering assist torque value obtained after correcting the initial steering assist torque according to the plurality of correction coefficients.

5. The electric power steering control method according to claim 4, characterized in that, After adding the final compensation value to the first correction value, the method further includes: Calculate the active return-to-center torque and add it to the second correction value to obtain the final steering assist torque of the car. The second correction value refers to the sum of the first correction value and the final compensation value.

6. An electronic control unit, characterized in that, include: A processor and a memory, wherein the memory stores a program that, when executed by the processor, implements the electric power steering control method as described in any one of claims 1 to 5.

7. An electric power steering system, characterized in that, include: The electronic control unit as described in claim 6.

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