A method and system for steer-by-wire transmission ratio adjustment

Abstract

The application provides a kind of drive-by-wire steering transmission ratio adjusting method and system, the method comprises the following steps: (11) determine the target transmission ratio of vehicle;(12) based on the deviation of the current transmission ratio of vehicle and target transmission ratio, adjust the rack position of steering mechanism, until the current transmission ratio of vehicle is adjusted to target transmission ratio.Based on the speed of vehicle, the stability and flexibility requirements of vehicle are balanced to dynamically adjust the transmission ratio of vehicle, when the speed of vehicle is higher, the large transmission ratio with small flexibility is selected, to ensure the stability and safety of vehicle, when the speed of vehicle is lower, the small transmission ratio with large flexibility is selected, the steering flexibility of vehicle is stronger, so that the driving operation is more convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transmission ratio adjustment, and provides a drive-by-wire steering transmission ratio adjustment method and system. BACKGROUND

[0002] The automobile steering system has undergone several stages over the years, including mechanical steering system (MS), hydraulic power steering system (HPS), electric hydraulic power steering system (EHPS), electronic power steering system (EPS), and drive-by-wire steering system (SBW).

[0003] The vehicle steering system is one of the core components of an automobile, and its main function is to change the driving direction of the vehicle. The traditional vehicle steering system adopts a fixed mechanical transmission ratio, which is difficult to ensure the stability of the vehicle during high-speed driving. With the development of automobile technology, variable transmission ratio online control technology has gradually emerged. This technology can adjust the transmission ratio of the vehicle through an electronic control unit, thereby realizing stable steering and efficient power transmission at different vehicle speeds.

[0004] The drive-by-wire steering system with variable transmission ratio is a technology that can adjust the steering effect according to the change in vehicle speed. The drive-by-wire steering system with variable transmission ratio has higher precision and better stability, but users cannot participate in the adjustment of the transmission ratio, which causes a lack of human-computer interaction experience. SUMMARY

[0005] In view of this, the present application provides a drive-by-wire steering transmission ratio adjustment method, which aims to improve the above-mentioned problems.

[0006] Specifically, the technical scheme includes the following:

[0007] On the one hand, the present application provides a drive-by-wire steering transmission ratio adjustment method, which includes the following steps:

[0008] (11) determining the target transmission ratio of the vehicle;

[0009] (12) adjusting the rack position of the steering mechanism based on the deviation between the current transmission ratio of the vehicle and the target transmission ratio until the current transmission ratio of the vehicle is adjusted to the target transmission ratio.

[0010] In some embodiments, the transmission ratio required for the current vehicle speed is determined, and the transmission ratio required for the current vehicle speed is taken as the target transmission ratio.

[0011] In some embodiments, the target transmission ratio is determined in the following manner:

[0012] read the current vehicle speed, determine the speed sub-interval in which the current vehicle speed is located;

[0013] reading the transmission ratio of the speed sub-interval in which the current vehicle speed is located from the vehicle speed sub-interval-transmission ratio mapping table, and taking the current read transmission ratio as the target transmission ratio;

[0014] The greater the vehicle speed corresponding to the speed sub-interval, the greater the transmission ratio corresponding to the speed sub-interval.

[0015] In some embodiments, the transmission ratio required by the current vehicle speed is determined, and the target transmission ratio is formed based on the transmission ratio required by the current vehicle speed and the expected transmission ratio selected by the user.

[0016] In some embodiments, the determination process of the target transmission ratio is as follows:

[0017] (221) converting the expected transmission ratio selected by the user into the transmission ratio preference degree and preference direction of the user;

[0018] (222) determining the adjustment direction of the transmission ratio required by the current vehicle speed based on the transmission ratio preference direction of the user, determining the adjustment amplitude of the transmission ratio required by the current vehicle speed in the adjustment direction based on the transmission ratio preference degree of the user, and forming the target transmission ratio.

[0019] In some embodiments, the determination method of the transmission ratio preference degree and preference direction of the user is as follows:

[0020] Based on the expected transmission ratio r0 selected by the user, the preference value p of the user for the small transmission ratio is calculated as p=(r max -r0) / (r max -r min ); if the preference value p is greater than or equal to 0.5, the transmission ratio preference direction of the user is small transmission ratio, and the preference degree is p; if the preference value p is less than 0.5, the transmission ratio preference direction of the user is large transmission ratio, and the preference degree is 1-p;

[0021] Wherein, r rmin , r max are the minimum transmission ratio and the maximum transmission ratio in the current selectable transmission ratio interval, respectively.

[0022] In some embodiments, the expected transmission ratio selected from the current output selectable transmission ratio interval is different in different driving modes.

[0023] In some embodiments, the target transmission ratio is output through the vehicle-mounted large screen.

[0024] On the other hand, the embodiments of the present application provide a steer-by-wire transmission ratio adjustment system, which comprises:

[0025] a steering wheel execution controller HWA, a front wheel execution controller RWA in communication connection with the steering wheel execution controller HWA, and the front wheel execution controller RWA being used for controlling a steering mechanism.

[0026] The steering wheel execution controller HWA reads the current vehicle speed, and controls the front wheel execution controller RWA to adjust the rack position of the steering mechanism based on the above-mentioned steer-by-wire transmission ratio adjustment method until the current transmission ratio of the vehicle reaches the target transmission ratio, which is determined based on the current vehicle speed.

[0027] In some embodiments, the system further comprises:

[0028] a large screen on the vehicle, which is communicatively connected to the steering wheel execution controller HWA,

[0029] based on the user-selected desired transmission ratio input by the large screen on the vehicle, the desired transmission ratio is sent to the steering wheel execution controller HWA, and the front wheel execution controller RWA is controlled to adjust the rack position of the steering mechanism based on the above-mentioned steer-by-wire transmission ratio adjustment method until the current transmission ratio of the vehicle reaches the target transmission ratio, which is determined based on the current vehicle speed and the user-selected desired transmission ratio.

[0030] The present application dynamically adjusts the transmission ratio of the vehicle based on the vehicle speed, and converts the user-set desired speed into the user's preference for the transmission ratio while considering the balance between the stability and flexibility of the vehicle, adjusts the transmission ratio required for the current speed based on the user's preference for the transmission ratio, not only integrates the user's preference for the transmission ratio into the adjustment of the transmission ratio of the vehicle, but also introduces the design of human-computer interaction into the adjustment of the transmission ratio, greatly improving the user experience. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 A flowchart of the steer-by-wire transmission ratio adjustment method provided for the first embodiment of the present application is shown in the figure.

[0033] Figure 2 A flowchart of the steer-by-wire transmission ratio adjustment method provided for the second embodiment of the present application is shown in the figure.

[0034] Figure 3 A structural schematic diagram of the steer-by-wire transmission ratio adjustment system provided for the embodiments of the present application is shown in the figure.

[0035] The specific embodiments of the present application have been shown by the above drawings, and will be described in more detail hereinafter. These drawings and the written description are not intended to restrict the scope of the present application in any way, but to illustrate the concept of the present application by reference to specific embodiments. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of the present application.

[0037] Unless otherwise defined, all technical terms used in the embodiments of the present application have the same meanings as commonly understood by those of ordinary skill in the art.

[0038] Figure 1 A flow chart of the drive-by-wire steering transmission ratio adjustment method provided for the first embodiment of the present application is shown in the figure, and the method comprises the following steps:

[0039] (11) determining the transmission ratio required by the current vehicle speed, and taking the transmission ratio as a target transmission ratio;

[0040] (12) adjusting the rack position of the steering mechanism based on the deviation of the current transmission ratio of the vehicle from the target transmission ratio, changing the steering angle of the steering wheel, adjusting the transmission ratio of the vehicle, and adjusting the current transmission ratio of the vehicle to the target transmission ratio.

[0041] Since the vehicle speed may change in real time during driving, in order to avoid excessively high adjustment frequency of the transmission ratio, the speed range of the vehicle is divided into several speed sub-ranges, and the transmission ratio of each speed sub-range is calibrated to form a mapping table of speed sub-range-transmission ratio. In order to comprehensively consider the safety and steering sensitivity of the steering wheel of the vehicle, the transmission ratio increases with the increase of the vehicle speed, a smaller transmission ratio is set for the speed sub-range with smaller speed, the steering flexibility of the vehicle driving at low speed is increased, the driving operation is more convenient, a larger transmission ratio is set for the speed sub-range with larger speed, the steering flexibility of the vehicle driving at high speed is reduced, and the stability and safety of the vehicle are ensured. Therefore, the method for determining the target transmission ratio of the vehicle is as follows:

[0042] (111) reading the current vehicle speed of the vehicle, and determining the speed sub-range in which the current vehicle speed is located;

[0043] (112) reading the transmission ratio of the speed sub-range in which the current vehicle speed is located from the mapping table of speed sub-range-transmission ratio, and taking the currently read transmission ratio as the target transmission ratio.

[0044] After determining the target transmission ratio of the vehicle at present, the actual transmission ratio of the vehicle at present needs to be obtained, the transmission ratio of the vehicle at present is the ratio of the steering wheel steering angle and the front wheel steering angle (the vehicle steering angle), and then the difference between the current transmission ratio and the target transmission ratio is determined, the difference is input into the PID algorithm, the PID algorithm performs closed-loop control on the rack position of the steering mechanism, until the current transmission ratio of the vehicle is the target transmission ratio, when the steering angle output by the steering wheel changes and the vehicle speed changes, the rack position of the steering mechanism is adjusted, and the adjustment of the current steering ratio of the vehicle is realized.

[0045] The transmission ratio of the vehicle is dynamically adjusted based on the vehicle speed, the stability and flexibility requirements of the vehicle are balanced, when the vehicle speed is high, the large transmission ratio with small flexibility is selected, the stability and safety of the vehicle are ensured, when the vehicle speed is low, the small transmission ratio with large flexibility is selected, the steering flexibility of the vehicle is strong, and the driving operation is more convenient.

[0046] Figure 2 A flowchart of the drive-by-wire steering transmission ratio adjustment method provided in the second embodiment of the present application is provided, and the method comprises the following steps:

[0047] (21) receiving the expected transmission ratio selected by the user from the selectable transmission ratio interval;

[0048] In the embodiment of the present application, after the user triggers the transmission ratio setting operation, the vehicle-mounted large screen outputs the selectable transmission ratio interval for the user to select, the user selects a transmission ratio based on the outputted selectable transmission ratio interval, the vehicle-mounted large screen displays the transmission ratio selected by the user again, and after confirming the selected transmission ratio, the transmission ratio is taken as the expected transmission ratio of the user.

[0049] In the embodiment of the present application, the selectable transmission ratio interval outputted by the vehicle-mounted large screen is different under different driving modes, if the driving modes include: comfort, normal and sports modes, the selectable transmission ratio interval corresponding to each driving mode is set in advance, after the user triggers the transmission ratio setting operation, the selectable transmission ratio interval corresponding to the driving mode currently selected by the vehicle is directly outputted, or after the user triggers the transmission ratio setting operation, the selectable driving mode is outputted, the selectable transmission ratio interval corresponding to the driving mode currently selected by the user is outputted, and the user selects the expected transmission ratio based on the selectable transmission ratio interval.

[0050] (22) determining the transmission ratio required by the current vehicle speed, and forming a target transmission ratio based on the transmission ratio required by the current vehicle speed and the expected transmission ratio selected by the user;

[0051] The method for determining the required transmission ratio of the current vehicle speed has been described in detail in Embodiment One, and will not be described again here. The desired transmission ratio selected by the user from the optional transmission ratio interval reflects the user's preference for the size of the transmission ratio. If the user selects a transmission ratio close to the minimum transmission ratio r rmin from the optional transmission ratio interval [r max , r rmin ], it indicates that the user prefers a small transmission ratio, and vice versa. If the user selects a transmission ratio close to the maximum transmission ratio r max from the optional transmission ratio interval [r rmin , r max ], it indicates that the user prefers a large transmission ratio. Based on the user's preference for the size of the transmission ratio, the required transmission ratio of the current vehicle speed is fine-tuned. If the user prefers a large transmission ratio, the user values the stability of the vehicle more, and thus the required transmission ratio of the current vehicle speed is increased. If the user prefers a small transmission ratio, the user values the flexibility of the vehicle more, and thus the required transmission ratio of the current vehicle speed is decreased. The fine-tuned transmission ratio is taken as the target transmission ratio, which comprehensively considers the user's preference, the stability of the vehicle and the flexibility of the vehicle.

[0052] In the examples of the present application, the fine-tuning method of the required transmission ratio of the current vehicle speed is as follows:

[0053] (221) converting the desired transmission ratio selected by the user into the user's transmission ratio preference degree and preference direction;

[0054] (222) determining the adjustment direction of the required transmission ratio of the current vehicle speed based on the user's transmission ratio preference direction, and determining the adjustment amplitude of the required transmission ratio of the current vehicle speed in the adjustment direction based on the user's transmission ratio preference degree.

[0055] When the user selects a transmission ratio r0 from the optional transmission ratio interval [r rmin , r max ], the user's preference value for a small steering ratio is calculated as p=(r max -r0) / (r max -r min ). If the preference value p is greater than or equal to 0.5, it is determined that the user's transmission ratio preference direction is a small transmission ratio, and the preference degree is p. If the preference value p is less than 0.5, it is determined that the user's transmission ratio preference direction is a large transmission ratio, and the preference degree is 1-p.

[0056] When the user's transmission ratio preference direction is a small transmission ratio, and the preference degree is p, the required transmission ratio r of the current vehicle speed is decreased, and the decrease amplitude is p*r p , where r pTo correspond to the maximum value of the allowable transmission ratio deviation in the preferred direction of the transmission ratio, it is known that the transmission ratio p*r is reduced on the basis of the required transmission ratio r of the front vehicle speed p That is, the target transmission ratio is formed, when the user's transmission ratio preferred direction is a large transmission ratio, and the preferred degree is 1-p, the required transmission ratio r of the current vehicle speed is increased, and the increased amplitude is (1-p)*r p It is known that the transmission ratio (1-p)*r is increased on the basis of the required transmission ratio r of the front vehicle speed p That is, the target transmission ratio is formed.

[0057] (23) Adjusting the rack position of the steering mechanism based on the deviation of the current transmission ratio from the target transmission ratio, changing the steering angle of the steering wheel, and adjusting the transmission ratio of the vehicle until the current transmission ratio of the vehicle is adjusted to the target transmission ratio.

[0058] The vehicle transmission ratio adjustment process based on the target transmission ratio has been described in detail in Embodiment One, and will not be repeated here. In order to make the user more intuitive to know the current transmission ratio of the vehicle, the determined target transmission ratio is output through the vehicle-mounted large screen, and the user can directly read out the current transmission ratio of the vehicle through the vehicle-mounted large screen.

[0059] The present application dynamically adjusts the transmission ratio of the vehicle based on the vehicle speed, balances the stability and flexibility of the vehicle, converts the desired speed set by the user into the user's preference for the transmission ratio, adjusts the transmission ratio required by the current vehicle speed based on the user's preference for the transmission ratio, not only integrates the user's preference for the transmission ratio into the adjustment of the vehicle transmission ratio, but also introduces the design of human-computer interaction into the adjustment of the transmission ratio, greatly improving the user experience.

[0060] Figure 3 The structure diagram of the drive-by-wire steering transmission ratio adjustment system provided by the embodiment of the present application, for the convenience of description, only the part related to the embodiment of the application is shown, and the system comprises:

[0061] The steering wheel execution controller HWA is in communication connection with the front wheel execution controller RWA, and the front wheel execution controller RWA is used to control the steering mechanism;

[0062] The steering wheel execution controller HWA reads the current vehicle speed, and controls the front wheel execution controller RWA to adjust the rack position of the steering mechanism based on the above drive-by-wire steering transmission ratio adjustment method, until the current transmission ratio of the vehicle reaches the target transmission ratio, the target transmission ratio is determined based on the current vehicle speed, and the stability and flexibility requirements of the vehicle are balanced, when the vehicle speed is high, a large transmission ratio with small flexibility is selected to ensure the stability and safety of the vehicle, and when the vehicle speed is low, a small transmission ratio with large flexibility is selected, the steering flexibility of the vehicle is strong, and the driving operation is more convenient.

[0063] In the embodiments of the present application, the system further comprises:

[0064] The large screen on the vehicle is in communication connection with the steering wheel execution controller HWA,

[0065] The user selects the desired transmission ratio based on the input of the large screen on the vehicle, and sends the desired transmission ratio to the steering wheel execution controller HWA. The rack position of the steering mechanism is adjusted by the front wheel execution controller RWA based on the above-mentioned steering transmission ratio adjustment method until the current transmission ratio of the vehicle reaches the target transmission ratio. The target transmission ratio is determined based on the current speed of the vehicle and the user's selected desired transmission ratio. The transmission ratio required for the current speed is adjusted based on the user's preference for the transmission ratio. Not only does this integrate the user's preference for the transmission ratio into the adjustment of the vehicle transmission ratio, but it also introduces the design of human-computer interaction into the adjustment of the transmission ratio, greatly improving the user experience.

[0066] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is intended to encompass all alternatives, modifications and equivalents thereof within the scope of the present application. The scope of the present application is not intended to be limited to the particular structures and arrangements described herein, but rather extends to and includes all structures and arrangements that are within the scope of the present application.

[0067] It should be understood that the present application is not limited to the precise construction and methods described above and shown in the attached drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present application. The scope of the present application is limited only by the claims appended hereto.

Claims

1. A steer-by-wire transmission ratio adjustment method, characterized by, The method comprises the following steps: (11) determining a target transmission ratio of the vehicle; (12) adjusting the rack position of the steering mechanism based on the deviation of the current transmission ratio of the vehicle from the target transmission ratio until the current transmission ratio of the vehicle is adjusted to the target transmission ratio; The transmission ratio required for the current vehicle speed is determined, and the target transmission ratio is formed based on the transmission ratio required for the current vehicle speed and the expected transmission ratio selected by the user; The determination process of the target transmission ratio is specifically as follows: (221) converting the expected transmission ratio selected by the user into a transmission ratio preference degree and a preference direction of the user; (222) determining the adjustment direction of the transmission ratio required for the current vehicle speed based on the transmission ratio preference direction of the user, determining the adjustment amplitude of the transmission ratio required for the current vehicle speed in the adjustment direction based on the transmission ratio preference degree of the user, and forming the target transmission ratio; The determination method of the transmission ratio preference degree and the preference direction of the user is specifically as follows: Based on the user-selected desired transmission ratio r0, a user preference value p = (r max - r0) / (r max - r min ) for a small steering ratio is calculated; if the preference value p is greater than or equal to 0.5, then the user's steering ratio preference direction is a small transmission ratio, and the preference degree is p; if the preference value p is less than 0.5, then it is determined that the user's transmission ratio preference direction is a large transmission ratio, and the preference degree is 1-p; wherein r min , r max are the minimum transmission ratio, the maximum transmission ratio, respectively, in the current selectable transmission ratio interval.

2. A steer-by-wire ratio adjustment method according to claim 1, characterized in that, The expected transmission ratio is selected from the current output selectable transmission ratio interval, and the selectable transmission ratio interval is different in different driving modes.

3. The by-wire steering ratio adjustment method of claim 1, wherein, The target transmission ratio is output through the vehicle-mounted large screen.

4. A steer-by-wire transmission ratio adjustment system characterized by, The system comprises: A steering wheel execution controller HWA and a front wheel execution controller RWA in communication connection with the steering wheel execution controller HWA, the front wheel execution controller RWA being used to control the steering mechanism; The steering wheel execution controller HWA acquires the current vehicle speed, and controls the front wheel execution controller RWA to adjust the rack position of the steering mechanism through the line control steering transmission ratio adjustment method in any one of claims 1 to 3 until the current transmission ratio of the vehicle reaches the target transmission ratio, the target transmission ratio being determined based on the current vehicle speed.

5. A steer-by-wire ratio adjustment system as claimed in claim 4, wherein, The system further comprises: A vehicle-mounted large screen in communication connection with the steering wheel execution controller HWA, The expected transmission ratio selected by the user is input based on the vehicle-mounted large screen, and the expected transmission ratio is sent to the steering wheel execution controller HWA, the front wheel execution controller RWA is controlled to adjust the rack position of the steering mechanism based on the line control steering transmission ratio adjustment method until the current transmission ratio of the vehicle reaches the target transmission ratio, the target transmission ratio being determined based on the current vehicle speed and the expected transmission ratio selected by the user.

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