Steer-by-wire transmission ratio adjusting method and system

Abstract

The invention provides a steer-by-wire transmission ratio adjusting method and system. The steer-by-wire transmission ratio adjusting method comprises the following steps that (11) the target transmission ratio of a vehicle is determined; and (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. The transmission ratio of the vehicle is dynamically adjusted based on the vehicle speed, the stability and flexibility requirements of the vehicle are considered in a balanced mode, when the vehicle speed is high, the large transmission ratio with the small flexibility is selected, the stability and safety of the vehicle are ensured, when the vehicle speed is low, the small transmission ratio with the large flexibility is selected, the steering flexibility of the vehicle is high, and driving operation is more convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission ratio adjustment, and provides a method and system for adjusting the transmission ratio of a wire-controlled steering system. Background Art

[0002] Over the years, the automobile steering system has gone through several stages, including mechanical steering system (MS), hydraulic power steering system (HPS), electric hydraulic power steering system (EHPS), electronic power steering system (EPS) and steer-by-wire system (SBW).

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

[0004] The variable transmission ratio steer-by-wire system is a technology that can adjust the steering effect according to changes in vehicle speed. The variable transmission ratio steer-by-wire system has higher precision and better stability, but users cannot participate in adjusting the transmission ratio, and there is a problem of insufficient human-computer interaction experience. Summary of the invention

[0005] In view of this, the present application provides a method for adjusting the transmission ratio of a wire-controlled steering system, aiming to improve the above-mentioned problem.

[0006] Specifically, the following technical solutions are included:

[0007] On the one hand, an embodiment of the present application provides a method for adjusting a steer-by-wire transmission ratio, the method comprising the following steps:

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

[0009] (12) Based on the deviation between the current transmission ratio of the vehicle and the target transmission ratio, the rack position of the steering mechanism is adjusted 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 used as the target transmission ratio.

[0011] In some embodiments, the method for determining the target transmission ratio is as follows:

[0012] Read the current speed of the vehicle and determine the speed sub-interval in which the current speed is located;

[0013] Reading the transmission ratio of the speed sub-interval where the current vehicle speed is located from the vehicle speed sub-interval-transmission ratio mapping table, and using the currently 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, a required gear ratio for a current vehicle speed is determined, and a target gear ratio is formed based on the required gear ratio for the current vehicle speed and a desired gear ratio selected by a user.

[0016] In some embodiments, the target transmission ratio is determined as follows:

[0017] (221) converting the desired transmission ratio selected by the user into the user's transmission ratio preference degree and preference direction;

[0018] (222) Determine an adjustment direction of the transmission ratio required for the current vehicle speed based on the user's transmission ratio preference direction, and determine an adjustment amplitude of the transmission ratio required for the current vehicle speed in the adjustment direction based on the user's transmission ratio preference degree, to form a target transmission ratio.

[0019] In some embodiments, the method for determining the user's transmission ratio preference degree and preference direction is as follows:

[0020] Based on the desired transmission ratio r0 selected by the user, the user's preference value for a small steering ratio p is calculated = (r max -r0) / (r max -r min ); if the preference value p is greater than or equal to 0.5, the user's rotation 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;

[0021] Among them, r rmin 、r max They are respectively the minimum transmission ratio and the maximum transmission ratio in the current optional transmission ratio range.

[0022] In some embodiments, the desired gear ratio is selected from the currently output selectable gear ratio range, and the selectable gear ratio ranges in different driving modes are different.

[0023] In some embodiments, the target transmission ratio is output via a large vehicle screen.

[0024] On the other hand, an embodiment of the present application provides a steer-by-wire transmission ratio adjustment system, the system comprising:

[0025] A steering wheel actuator controller HWA, a front wheel actuator controller RWA communicatively connected to the steering wheel actuator controller HWA, the front wheel actuator controller RWA being used to control a steering mechanism;

[0026] The steering wheel actuator controller HWA reads the current vehicle speed and controls the front wheel actuator controller RWA to adjust the rack position of the steering mechanism based on the above-mentioned wire-controlled steering 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] The large in-vehicle screen is connected to the steering wheel actuator controller HWA.

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

[0030] The present invention dynamically adjusts the transmission ratio of the vehicle based on the vehicle speed. In addition to considering the balance between vehicle stability and vehicle flexibility, the desired speed set by the user is converted into the user's preference for the transmission ratio, and the transmission ratio required for the current vehicle speed is adjusted based on the user's preference for the transmission ratio. Not only does the user's preference for the transmission ratio be integrated into the adjustment of the vehicle's transmission ratio, but the design of human-computer interaction is also introduced into the adjustment of the transmission ratio, which greatly improves the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A flow chart of a method for adjusting a steer-by-wire transmission ratio provided in Embodiment 1 of the present invention;

[0033] Figure 2 A flow chart of a method for adjusting a steer-by-wire transmission ratio provided in Embodiment 2 of the present invention;

[0034] Figure 3 A schematic diagram of the structure of a steer-by-wire transmission ratio adjustment system provided by an embodiment of the present invention;

[0035] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this 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 This is a flow chart of a method for adjusting a steer-by-wire transmission ratio provided in Embodiment 1 of the present invention. The method comprises the following steps:

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

[0040] (12) Based on the deviation between the current transmission ratio of the vehicle and the target transmission ratio, the rack position of the steering mechanism is adjusted, the steering angle of the steering wheel is changed, and the transmission ratio of the vehicle is adjusted until the current transmission ratio of the vehicle is adjusted to the target transmission ratio.

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

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

[0043] (112) Read the transmission ratio of the speed sub-interval where the current vehicle speed is located from the vehicle speed sub-interval-transmission ratio mapping table, and use the currently read transmission ratio as the target transmission ratio.

[0044] After determining the vehicle's current target transmission ratio, it is necessary to obtain the vehicle's current actual transmission ratio. The vehicle's current transmission ratio is the ratio of the steering wheel steering angle to the front wheel steering angle (vehicle steering angle), and then determine the difference between the vehicle's current transmission ratio and the target transmission ratio. 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 vehicle's current transmission ratio 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 to adjust the vehicle's current steering ratio.

[0045] The present invention dynamically adjusts the transmission ratio of the vehicle based on the vehicle speed, taking into account the stability and flexibility requirements of the vehicle in a balanced manner. When the vehicle speed is high, a large transmission ratio with low flexibility is selected to ensure the stability and safety of the vehicle. When the vehicle speed is low, a small transmission ratio with high flexibility is selected. The vehicle has greater steering flexibility, making driving operations easier.

[0046] Figure 2 This is a flow chart of a method for adjusting a steering-by-wire transmission ratio provided in Embodiment 2 of the present invention. The method comprises the following steps:

[0047] (21) receiving a desired transmission ratio selected by a user from a selectable transmission ratio range;

[0048] In an embodiment of the present invention, after the user triggers the transmission ratio setting operation, the optional transmission ratio range available for the user to select is output through the vehicle-mounted large screen. The user selects a transmission ratio based on the output optional transmission ratio range, and the vehicle-mounted large screen displays the transmission ratio selected by the user again. After confirming the selected transmission ratio, the transmission ratio is used as the user's desired transmission ratio.

[0049] In an embodiment of the present invention, the optional transmission ratio ranges output by the on-board large screen in different driving modes are different. If the driving modes include: comfort, normal and sport modes, the optional transmission ratio range corresponding to each driving mode is pre-set, and after the user triggers the transmission ratio setting operation, the optional transmission ratio range corresponding to the currently selected driving mode of the vehicle is directly output. Alternatively, after the user triggers the transmission ratio setting operation, the selectable driving mode is output, and the optional transmission ratio range corresponding to the driving mode currently selected by the user is output, and the user selects the expected transmission ratio based on the optional transmission ratio range.

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

[0051] The method for determining the transmission ratio required for the current vehicle speed has been described in detail in the first embodiment and will not be repeated here. The desired transmission ratio selected by the user from the optional transmission ratio range reflects the user's preference for the transmission ratio. rmin , r max ] selects a gear ratio close to the minimum rmin The transmission ratio of the user is smaller, which means that the user prefers a smaller transmission ratio. On the contrary, the user chooses a smaller transmission ratio from the optional transmission ratio range [r rmin , r max ] selects a gear ratio close to the maximum max The transmission ratio of indicates that the user prefers a large transmission ratio. Based on the user's preference for the transmission ratio, the transmission ratio required for the current vehicle speed is fine-tuned. If the user prefers a large transmission ratio and the user attaches more importance to the stability of the vehicle, the transmission ratio required for the current vehicle speed is increased. If the user prefers a small transmission ratio and the user attaches more importance to the flexibility of the vehicle, the transmission ratio required for the current vehicle speed is reduced. Based on the above method, the transmission ratio required for the current vehicle speed is fine-tuned and the fine-tuned transmission ratio is used as the target transmission ratio, which comprehensively considers the user preference, vehicle stability and vehicle flexibility.

[0052] In the example of the present invention, the method for fine-tuning the transmission ratio required for the current vehicle speed is specifically 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 an adjustment direction of the transmission ratio required for the current vehicle speed based on the user's transmission ratio preference direction, and determining an adjustment amplitude of the transmission ratio required for the current vehicle speed in the adjustment direction based on the user's transmission ratio preference degree.

[0055] In the user selectable transmission ratio range [r rmin , r max ] Select the transmission ratio r0, calculate the user's preference value for small steering ratio 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 is a small transmission ratio and the preference degree is p, the transmission ratio r required to reduce the current vehicle speed is reduced by p*r p , where r pis the maximum value of the gear ratio deviation allowed in the preferred direction. It can be seen that the gear ratio p*r is reduced based on the gear ratio r required by the front vehicle speed. p That is, the target transmission ratio is formed. When the user's transmission ratio preference direction is a large transmission ratio and the preference degree is 1-p, the transmission ratio r required for the current vehicle speed is increased by (1-p)*r p , it can be seen that the increased transmission ratio (1-p)*r based on the transmission ratio r required by the previous vehicle speed p That constitutes the target transmission ratio.

[0057] (23) Based on the deviation between the current transmission ratio and the target transmission ratio, the rack position of the steering mechanism is adjusted, the steering angle of the steering wheel is changed, and the transmission ratio of the vehicle is adjusted 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 the first embodiment, and will not be repeated here. In order to allow the user to more intuitively 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 the current transmission ratio of the vehicle through the vehicle-mounted large screen.

[0059] The present invention dynamically adjusts the transmission ratio of the vehicle based on the vehicle speed. In addition to considering the balance between vehicle stability and vehicle flexibility, the desired speed set by the user is converted into the user's preference for the transmission ratio, and the transmission ratio required for the current vehicle speed is adjusted based on the user's preference for the transmission ratio. Not only does the user's preference for the transmission ratio be integrated into the adjustment of the vehicle's transmission ratio, but the design of human-computer interaction is also introduced into the adjustment of the transmission ratio, which greatly improves the user experience.

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

[0061] A steering wheel actuator controller HWA, a front wheel actuator controller RWA communicatively connected to the steering wheel actuator controller HWA, the front wheel actuator controller RWA being used to control a steering mechanism;

[0062] The steering wheel actuator controller HWA reads the current speed of the vehicle, and controls the front wheel actuator controller RWA to adjust the rack position of the steering mechanism based on the above-mentioned wire-controlled 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 balances the stability and flexibility requirements of the vehicle. When the speed is high, a large transmission ratio with low flexibility is selected to ensure the stability and safety of the vehicle. When the speed is low, a small transmission ratio with high flexibility is selected. The vehicle has greater steering flexibility, making driving operations easier.

[0063] In an embodiment of the present invention, the system further includes:

[0064] The large in-vehicle screen is connected to the steering wheel actuator controller HWA.

[0065] The desired transmission ratio selected by the user is input based on the in-vehicle large screen, and the desired transmission ratio is sent to the steering wheel actuator controller HWA. The front wheel actuator controller RWA is controlled to adjust the rack position of the steering mechanism based on the above-mentioned wire-controlled 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 desired transmission ratio selected by the user. The transmission ratio required for the current vehicle speed is adjusted based on the user's preference for the transmission ratio. Not only the user's preference for the transmission ratio is integrated into the adjustment of the vehicle's transmission ratio, but also the transmission ratio adjustment introduced into the design of human-computer interaction, which greatly improves the user experience.

[0066] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the present application disclosed 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 common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only.

[0067] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for adjusting a steering-by-wire transmission ratio, characterized in that: The method comprises the following steps: (11) determining a target transmission ratio of the vehicle; (12) Based on the deviation between the current transmission ratio of the vehicle and the target transmission ratio, the rack position of the steering mechanism is adjusted until the current transmission ratio of the vehicle is adjusted to the target transmission ratio.

2. The method for adjusting the transmission ratio of the steer-by-wire system according to claim 1, characterized in that: The transmission ratio required for the current speed of the vehicle is determined, and the transmission ratio required for the current speed is used as the target transmission ratio.

3. The method for adjusting the transmission ratio of the steer-by-wire system as claimed in claim 2, characterized in that: The method for determining the target transmission ratio is as follows: Read the current speed of the vehicle and determine the speed sub-interval in which the current speed is located; Reading the transmission ratio of the speed sub-interval where the current vehicle speed is located from the vehicle speed sub-interval-transmission ratio mapping table, and using the currently read transmission ratio as the target transmission ratio; The greater the vehicle speed corresponding to the speed sub-interval, the greater the transmission ratio corresponding to the speed sub-interval.

4. The method for adjusting the transmission ratio of the steer-by-wire system according to claim 1, characterized in that: The gear ratio required for the current vehicle speed is determined, and a target gear ratio is formed based on the gear ratio required for the current vehicle speed and the desired gear ratio selected by the user.

5. The method for adjusting the transmission ratio of the steer-by-wire system as claimed in claim 4, characterized in that: The process of determining the target transmission ratio is as follows: (221) converting the desired transmission ratio selected by the user into the user's transmission ratio preference degree and preference direction; (222) Determine an adjustment direction of the transmission ratio required for the current vehicle speed based on the user's transmission ratio preference direction, and determine an adjustment amplitude of the transmission ratio required for the current vehicle speed in the adjustment direction based on the user's transmission ratio preference degree, to form a target transmission ratio.

6. The method for adjusting the steer-by-wire transmission ratio as claimed in claim 1, characterized in that: The method for determining the user's transmission ratio preference degree and preference direction is specifically as follows: Based on the desired transmission ratio r0 selected by the user, the user's preference value for a small steering ratio p is calculated = (r max -r0) / (r max -r min ); if the preference value p is greater than or equal to 0.5, the user's rotation 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; Among them, r rmin 、r max They are respectively the minimum transmission ratio and the maximum transmission ratio in the current optional transmission ratio range.

7. The method for adjusting the transmission ratio of the steer-by-wire system according to claims 4 to 6, characterized in that: The desired gear ratio is selected from the currently output selectable gear ratio range, and the selectable gear ratio range is different in different driving modes.

8. The method for adjusting the transmission ratio of the steer-by-wire system as claimed in claim 1, characterized in that: The target transmission ratio is output through the large screen on the vehicle.

9. A steer-by-wire transmission ratio adjustment system, characterized in that: The system comprises: A steering wheel actuator controller HWA, a front wheel actuator controller RWA communicatively connected to the steering wheel actuator controller HWA, the front wheel actuator controller RWA being used to control a steering mechanism; The steering wheel actuator controller HWA obtains the current speed of the vehicle, and controls the front wheel actuator controller RWA to adjust the rack position of the steering mechanism according to the wire-controlled steering transmission ratio adjustment method described in any one of claims 1 to 8 until the current transmission ratio of the vehicle reaches the target transmission ratio, which is determined based on the current speed of the vehicle.

10. The steer-by-wire transmission ratio adjustment system according to claim 9, characterized in that: The system further comprises: The large in-vehicle screen is connected to the steering wheel actuator controller HWA. The desired transmission ratio selected by the user is input into the vehicle's large screen and sent to the steering wheel actuator controller HWA. Based on the above-mentioned wire-controlled steering transmission ratio adjustment method, the front wheel actuator controller RWA is controlled to adjust the rack position of the steering mechanism until the vehicle's current transmission ratio reaches the target transmission ratio. The target transmission ratio is determined based on the vehicle's current speed and the desired transmission ratio selected by the user.

Images