Steering and Braking Angle Distribution Optimization Method and Device for Fully Drive-by-Wire Electric Vehicles

Abstract

This application relates to a method and apparatus for optimizing the steering and braking angle distribution of a fully steerable electric vehicle. The method includes: obtaining the user's deceleration requirements; based on the deceleration requirements, ensuring that the front and rear wheel adhesion rates of the fully steerable electric vehicle are equal, and calculating the front and rear wheel lateral forces under preset conditions; calculating the front and rear wheel steering angles during steering and braking of the fully steerable electric vehicle based on the front and rear wheel lateral forces, the front and rear wheel vertical forces, and a tire model, to optimize the distribution of the front and rear wheel steering angles and obtain the final optimized steering and braking angle distribution result. This solves the problems in related technologies, such as the difficulty in achieving redundant braking through a four-wheel independent steering system, which reduces driving safety, and the lack of reasonable distribution of the front and rear wheel steering angles, which reduces the stability of steering and braking.

Description

Technical Field

[0001] This application relates to the field of fully drive-by-wire electric vehicle technology, and in particular to a method and apparatus for optimizing the steering and braking angle distribution of a fully drive-by-wire electric vehicle. Background Technology

[0002] Currently, traditional automobiles, limited by their inherent chassis design, struggle to meet the demands of electrification and intelligentization. Fully steer-by-wire electric vehicles (FSEVs), based on four-wheel independent drive (WID), independent braking (WIB), and independent steering (WIS), offer controllable drive, braking force, and steering angle for each wheel. This not only satisfies the demands of electrification and intelligentization but also, due to its greater controllable degrees of freedom, allows for higher performance limits and easier implementation of active fault-tolerant control, demonstrating promising development prospects. Active fault-tolerant control, in particular, refers to the ability to reconfigure the operating modes of the remaining actuators and rationally allocate their actions when one or more actuators fail, ensuring stable vehicle operation. This is crucial for guaranteeing the safety of fully steer-by-wire electric vehicles.

[0003] In related technologies, research on active fault-tolerant control of electric vehicles focuses on the case of steering system failure. The principle is that when the steering system fails, the controller calculates the additional yaw moment of the whole vehicle and distributes it to each wheel. Redundant steering function is achieved by changing the distribution of four-wheel drive and braking force.

[0004] However, in related technologies, when the vehicle's drive and braking systems fail, it is difficult to perform redundant braking through the four-wheel independent steering system, which reduces driving safety. Furthermore, simply setting the steering angles of the front and rear wheels to be the same without properly distributing the steering angles of the front and rear wheels reduces the stability of steering and braking, which urgently needs improvement. Summary of the Invention

[0005] This application provides a method and apparatus for optimizing the steering and braking angle distribution of a fully steerable electric vehicle, in order to solve the problems in related technologies, such as the difficulty in redundant braking through the four-wheel independent steering system when the vehicle's drive and braking systems fail, which reduces driving safety, and the simple setting of the front and rear wheel angles to be the same without reasonable distribution of the front and rear wheel angles, which reduces the stability of steering and braking.

[0006] The first aspect of this application provides a method for optimizing the steering and braking angle allocation of a fully steerable electric vehicle, comprising the following steps: obtaining the user's deceleration requirements; based on the deceleration requirements, making the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle equal, and calculating the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle under preset conditions; and calculating the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the front wheel lateral force and rear wheel lateral force, the front wheel vertical force and rear wheel vertical force, and a tire model, so as to optimize the allocation of the front wheel angle and the rear wheel angle to obtain the final optimized steering and braking angle allocation result.

[0007] Optionally, in one embodiment of this application, before making the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle equal, the method further includes: obtaining the tire adhesion rate of the fully steerable electric vehicle from the ratio of the actual tire force of the fully steerable electric vehicle to the maximum tire force of the fully steerable electric vehicle.

[0008] Optionally, in one embodiment of this application, the step of making the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle equal based on the deceleration requirement to calculate the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle includes: establishing a first longitudinal dynamic equation of the fully steerable electric vehicle under the inward-pointing steering braking condition based on the deceleration requirement, and obtaining a second longitudinal dynamic equation according to the deceleration requirement and the first longitudinal dynamic equation; making the front wheel adhesion rate and the rear wheel adhesion rate equal based on the second longitudinal dynamic equation, and calculating the front wheel vertical force and rear wheel vertical force of the fully steerable electric vehicle; and calculating the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle according to the front wheel adhesion rate, the rear wheel adhesion rate, the front wheel vertical force, and the rear wheel vertical force under the preset conditions.

[0009] Optionally, in one embodiment of this application, the first longitudinal dynamic equation is:

[0010] ,

[0011] in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively.

[0012] The second longitudinal dynamic equation is:

[0013] ,

[0014] in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. For the overall vehicle quality, It is the acceleration due to gravity. It is the acceleration due to gravity. For windward area, This refers to air density.

[0015] Optionally, in one embodiment of this application, the step of calculating the front wheel angle and rear wheel angle of the fully steerable electric vehicle during steering and braking based on the front wheel lateral force, the rear wheel lateral force, the front wheel vertical force, the rear wheel vertical force, and the tire model includes: calculating the front wheel vertical force and rear wheel vertical force of the fully steerable electric vehicle based on the front wheel lateral force, the rear wheel lateral force, and the deceleration of the fully steerable electric vehicle, and calculating the front wheel angle and rear wheel angle of the fully steerable electric vehicle during steering and braking based on the tire model.

[0016] Optionally, in one embodiment of this application, the steering braking is at least one of the left wheel turning right and the right wheel turning left of the fully drive-by-wire electric vehicle.

[0017] A second aspect of this application provides a steering and braking angle allocation optimization device for a fully steerable electric vehicle, comprising: an acquisition module for acquiring a user's deceleration requirements; a calculation module for ensuring that the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle are equal based on the deceleration requirements, and calculating the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle under preset conditions; and an optimization module for calculating the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the front wheel lateral force and rear wheel lateral force, the front wheel vertical force and rear wheel vertical force, and a tire model, so as to optimize the allocation of the front wheel angle and rear wheel angle to obtain the final optimized steering and braking angle allocation result.

[0018] Optionally, in one embodiment of this application, it further includes: an acquisition module, used to obtain the tire adhesion rate of the fully steerable electric vehicle from the ratio of the actual tire force of the fully steerable electric vehicle to the maximum tire force of the fully steerable electric vehicle before making the front tire adhesion rate and the rear tire adhesion rate of the fully steerable electric vehicle equal.

[0019] Optionally, in one embodiment of this application, the calculation module includes: an establishment unit, configured to establish a first longitudinal dynamic equation for the fully steerable electric vehicle under an inward-pointing steering braking condition based on the deceleration requirement, and to obtain a second longitudinal dynamic equation based on the deceleration requirement and the first longitudinal dynamic equation; and a first calculation unit, configured to make the front wheel adhesion rate and the rear wheel adhesion rate equal based on the second longitudinal dynamic equation, and to calculate the front wheel vertical force and the rear wheel vertical force of the fully steerable electric vehicle, and, under the preset conditions, to calculate the front wheel lateral force and the rear wheel lateral force of the fully steerable electric vehicle based on the front wheel adhesion rate, the rear wheel adhesion rate, the front wheel vertical force, and the rear wheel vertical force.

[0020] Optionally, in one embodiment of this application, the first longitudinal dynamic equation is:

[0021] ,

[0022] in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively.

[0023] The second longitudinal dynamic equation is:

[0024] ,

[0025] in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. For the overall vehicle quality, It is the acceleration due to gravity. It is the acceleration due to gravity. For windward area, This refers to air density.

[0026] Optionally, in one embodiment of this application, the optimization module includes: a second calculation unit, used to calculate the front wheel vertical force and rear wheel vertical force of the fully steerable electric vehicle based on the front wheel lateral force, the rear wheel lateral force, and the deceleration of the fully steerable electric vehicle, and to calculate the front wheel steering angle and rear wheel steering angle of the fully steerable electric vehicle during steering braking based on the tire model.

[0027] Optionally, in one embodiment of this application, the steering braking is at least one of the left wheel turning right and the right wheel turning left of the fully drive-by-wire electric vehicle.

[0028] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steering and braking angle distribution optimization method for a fully drive-by-wire electric vehicle as described in the above embodiments.

[0029] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle.

[0030] This application's embodiments can optimize the allocation of front and rear wheel steering angles in a fully steerable electric vehicle, making the front and rear wheel adhesion rates approximately equal, thereby improving vehicle stability. Furthermore, this application reasonably simplifies the solution process for optimizing the steering angle allocation in a fully steerable electric vehicle, offering advantages such as ease of implementation and strong versatility. Thus, it solves the problems in related technologies, such as the difficulty in achieving redundant braking through a four-wheel independent steering system when the vehicle's drive and braking systems fail, reducing driving safety, and the problem of simply setting the front and rear wheel angles to be the same without reasonable allocation of the front and rear wheel angles, thus reducing steering and braking stability.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 This is a flowchart of a steering and braking angle distribution optimization method for a fully steerable electric vehicle according to an embodiment of this application;

[0034] Figure 2 This is a schematic diagram of braking deceleration at different steering angles when the front wheel steering angle and the rear wheel steering angle are the same in related technologies;

[0035] Figure 3 This is a tire model diagram of a steering and braking angle distribution optimization method for a fully steerable electric vehicle according to an embodiment of this application;

[0036] Figure 4Diagrams showing the front and rear wheel steering angle distribution under different deceleration requirements of related technologies and methods proposed in this application;

[0037] Figure 5 Simulation results of front and rear wheel adhesion rates under different deceleration requirements of related technologies and methods proposed in this application are shown.

[0038] Figure 6 This is a flowchart of a method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle according to an embodiment of this application;

[0039] Figure 7 This is a schematic diagram of a steering and braking angle distribution optimization device for a fully steerable electric vehicle according to an embodiment of this application;

[0040] Figure 8 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0041] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0042] The following describes a method and apparatus for optimizing the steering and braking angle distribution of a fully steerable electric vehicle according to embodiments of this application, with reference to the accompanying drawings. In the related technologies mentioned in the background section, when the vehicle's drive and braking systems fail, it is difficult to perform redundant braking through the four-wheel independent steering system, reducing driving safety. Furthermore, simply setting the front and rear wheel angles to be the same without a reasonable distribution of the front and rear wheel angles reduces steering and braking stability. This application provides a method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle. In this method, the front and rear wheel angles of the fully steerable electric vehicle can be optimized for steering and braking, making the front wheel adhesion rate and rear wheel adhesion rate approximately equal, thereby improving vehicle stability. Moreover, this application reasonably simplifies the solution process for optimizing the steering and braking angle distribution of a fully steerable electric vehicle, and has advantages such as ease of implementation and strong versatility. This solves the problems in related technologies, such as the difficulty in redundant braking through the four-wheel independent steering system when the vehicle's drive and braking systems fail, which reduces driving safety, and the fact that simply setting the front and rear wheel angles to be the same without reasonable distribution of the front and rear wheel angles reduces the stability of steering and braking.

[0043] Specifically, Figure 1 This is a flowchart illustrating a method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle, as provided in an embodiment of this application.

[0044] like Figure 1 As shown, the method for optimizing the steering and braking angle distribution of this fully steerable electric vehicle includes the following steps:

[0045] In step S101, the user's deceleration requirement is obtained.

[0046] Understandably, in related technologies, simulation studies of fully drive-by-wire electric vehicle models are conducted with an initial vehicle speed of 30 km / h, zero torque input to all four wheels, and identical front and rear wheel steering angles of 2°, 4°, 8°, 16°, 32°, 64°, and 90° (a figure-eight angle). The simulated braking deceleration results for different figure-eight angles are 0.375713856 m / s². 2 0.807258872 m / s 2 1.61780884 m / s 2 2.973005114 m / s 2 4.9990002m / s 2 7.233796296 m / s 2 and 7.548309179 m / s 2 ,like Figure 2 As shown, as the inward turning angle increases, the braking deceleration gradually increases, but the rate of increase slows down. The maximum braking deceleration generated by four-wheel inward turning is 7.548309179 m / s². 2 .

[0047] Therefore, in actual implementation, the embodiments of this application can obtain the user's deceleration requirements. Under certain deceleration requirements, it is convenient to calculate the tire lateral force of the fully steerable electric vehicle and reasonably allocate the steering and braking angles of the fully steerable electric vehicle, thereby improving the stability of the steering and braking conditions.

[0048] In step S102, based on the deceleration requirement, the front wheel adhesion rate and the rear wheel adhesion rate of the fully steerable electric vehicle are made equal, and the front wheel lateral force and the rear wheel lateral force of the fully steerable electric vehicle are calculated under preset conditions.

[0049] It is understood that the fully drive-by-wire electric vehicle in this application embodiment can be an electric vehicle with four-wheel independent drive, independent braking and independent steering functions; the preset conditions in this application embodiment facilitate the calculation of front wheel lateral force and rear wheel lateral force, which can provide support for the optimized allocation of front wheel steering angle and rear wheel steering angle of subsequent fully drive-by-wire electric vehicles.

[0050] As one possible approach, embodiments of this application can make the front and rear wheel adhesion rates of a fully steerable electric vehicle equal based on deceleration requirements, and calculate the front and rear wheel lateral forces of the fully steerable electric vehicle under certain conditions. This provides support for the subsequent optimized allocation of the front and rear wheel steering angles of the fully steerable electric vehicle for steering and braking, further improving the vehicle's stability.

[0051] It should be noted that the preset conditions can be set by those skilled in the art according to the actual situation, and no specific restrictions are imposed here.

[0052] Optionally, in one embodiment of this application, before making the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle equal, the method further includes: obtaining the tire adhesion rate of the fully steerable electric vehicle from the ratio of the actual tire force of the fully steerable electric vehicle to the maximum tire force of the fully steerable electric vehicle.

[0053] It is understood that the tire adhesion rate in the embodiments of this application can be the front wheel adhesion rate and the rear wheel adhesion rate.

[0054] In actual implementation, this application embodiment aims to improve stability as the goal of optimizing the distribution of front wheel steering angle and rear wheel steering angle in a fully steerable electric vehicle, and defines the tire adhesion rate formula as follows:

[0055] (1)

[0056] in, , and These are the longitudinal force, lateral force, and vertical force acting on the wheel, respectively. ; This is the road surface adhesion coefficient.

[0057] By definition, the tire adhesion rate of a fully steerable electric vehicle (SEV) is obtained by the ratio of its actual tire force to its maximum tire force, with a value ranging from 0 to 1. This indicates that the actual tire force is zero. This indicates that the actual tire force has reached the tire adhesion limit, and there is a risk of instability. Therefore, the tire adhesion rate is used as a stability indicator. The smaller the value, the greater the tire force margin and the more stable the car is.

[0058] In this embodiment, for the inward-pointing steering braking condition, both the drive and braking systems fail, therefore the longitudinal force on the tires is zero. Furthermore, to simplify the analysis, the following is set... Therefore, the tire adhesion ratio can be rewritten as:

[0059] (2)

[0060] The embodiment of this application can obtain the tire adhesion rate of a fully steerable electric vehicle from the ratio of the actual tire force to the maximum tire force of the fully steerable electric vehicle, thereby providing a basis for further optimizing the distribution of the front wheel steering angle and rear wheel steering angle of the fully steerable electric vehicle for steering and braking, and further improving the stability of the vehicle.

[0061] Optionally, in one embodiment of this application, based on deceleration requirements, the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle are made equal to calculate the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle. This includes: based on deceleration requirements, establishing a first longitudinal dynamic equation for the fully steerable electric vehicle under an inward-pointing steering braking condition, and obtaining a second longitudinal dynamic equation based on the deceleration requirements and the first longitudinal dynamic equation; based on the second longitudinal dynamic equation, making the front wheel adhesion rate and rear wheel adhesion rate equal, and calculating the front wheel vertical force and rear wheel vertical force of the fully steerable electric vehicle; and under preset conditions, calculating the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle based on the front wheel adhesion rate, rear wheel adhesion rate, front wheel vertical force, and rear wheel vertical force.

[0062] Specifically, in this embodiment, under the condition of meeting a certain deceleration requirement for a fully steerable electric vehicle, the mathematical relationship between the lateral forces of the front and rear wheels can be obtained based on the relevant vehicle dynamics equations. Based on the principles of vehicle dynamics, under the inward-pointing steering braking condition, the first longitudinal dynamic equation of the fully steerable electric vehicle is established:

[0063] (3)

[0064] in, For the longitudinal deceleration of the car, ; For longitudinal vehicle speed, ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. Other vehicle parameters are shown in Table 1. Table 1 is the vehicle parameter table, as shown in Table 1:

[0065] Table 1

[0066]

[0067] Given the deceleration requirement, equation (3) can be transformed into equation (4), that is, the second longitudinal dynamic equation can be obtained based on the deceleration requirement and the first longitudinal dynamic equation:

[0068] (4)

[0069] By setting the front wheel adhesion rate and the rear wheel adhesion rate of a fully steerable electric vehicle to be equal, we can obtain the following formula:

[0070] (5)

[0071] By ensuring that the front and rear wheel adhesion rates of a fully steerable electric vehicle are equal, in this embodiment of the application, when the tire force of a certain tire is close to saturation while other tires have a large tire adhesion margin, the optimization method can reduce the tire force of the tire that is close to saturation. The resulting deficiency in the combined force required by the whole vehicle is compensated by increasing the tire force of other tires, thereby making full use of the adhesion capacity of all tires and improving vehicle stability.

[0072] Furthermore, the vertical force of the tire in the embodiments of this application can be calculated by the following formula:

[0073] (6)

[0074] in, To ensure the quality of fully controlled electric vehicles, It is the acceleration due to gravity. The distance from the center of gravity to the front wheel. For the longitudinal deceleration of fully drive-by-wire electric vehicles, For the height of the center of mass, This refers to the wheelbase.

[0075] Combining formulas (5) and (6), we get:

[0076]

[0077] According to formulas (4), (7) and as shown in the figure Figure 3 The tire model shown, given the deceleration requirement, can theoretically be solved. , and corresponding , However, due to the nonlinearity and complexity of formula (4) and tire model, the computation cost is relatively high. Therefore, a simplified algorithm is proposed. The simplified algorithm is shown in the subsequent step S103. Under the target conditions, the above mathematical relationship is simplified and then combined, so that the lateral forces of the front and rear wheels can be calculated without a large computation cost.

[0078] It should be noted that the preset conditions can be set by those skilled in the art according to the actual situation, and no specific restrictions are imposed here.

[0079] Optionally, in one embodiment of this application, the first longitudinal dynamic equation is:

[0080] ,

[0081] in, For the longitudinal deceleration of fully drive-by-wire electric vehicles, ; For the longitudinal speed of fully line-controlled electric vehicles, ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively.

[0082] The second longitudinal dynamic equation is:

[0083] ,

[0084] in, For the longitudinal deceleration of fully drive-by-wire electric vehicles, ; For the longitudinal speed of fully line-controlled electric vehicles, ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. For the overall vehicle quality, It is the acceleration due to gravity. It is the acceleration due to gravity. For windward area, This refers to air density.

[0085] In actual implementation, the embodiments of this application can obtain the first longitudinal dynamic equation according to the driver's deceleration requirements, and the embodiments of this application can transform the first longitudinal dynamic equation to obtain the second longitudinal dynamic equation. Based on the first and second longitudinal dynamic equations, support can be provided for the subsequent calculation of the front wheel steering angle and rear wheel steering angle of the fully steerable electric vehicle, thereby ensuring that the solution is simple and easy to implement.

[0086] In step S103, the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle are calculated based on the front wheel lateral force, rear wheel lateral force, front wheel vertical force, rear wheel vertical force, and tire model, so as to optimize the allocation of the front wheel angle and rear wheel angle and obtain the final optimized allocation result of steering and braking angle.

[0087] In actual implementation, the embodiments of this application can assume that the front wheel steering angle and the rear wheel steering angle of the fully steered electric vehicle are approximately the same, denoted as:

[0088] (8)

[0089] At this point, the above formula (4) can be simplified to:

[0090] (9)

[0091] in, This can be achieved by slowing down demand and Figure 1 The result was obtained by looking up the table.

[0092] Combining equations (7) and (9), we can obtain:

[0093] (10)

[0094] in, , .

[0095] The embodiments of this application can be based on the lateral forces of the front wheels and the lateral forces of the rear wheels. The vertical forces of the front wheels and the rear wheels can be calculated by the deceleration requirements and the above formula (6). The corresponding front wheel angle and rear wheel angle can be obtained by looking up the table through the tire model. The front wheel angle and rear wheel angle can be optimized and allocated to obtain the final optimized allocation result of the steering and braking angle. This ensures that the solution process of the optimization method for the steering and braking angle allocation of the fully steerable electric vehicle is reasonably simplified. The solution is simple, easy to implement, and has typicality and universality.

[0096] Optionally, in one embodiment of this application, calculating the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the front wheel lateral force, rear wheel lateral force, front wheel vertical force, rear wheel vertical force, and tire model includes: calculating the front wheel vertical force and rear wheel vertical force of the fully steerable electric vehicle based on the front wheel lateral force, rear wheel lateral force, and deceleration of the fully steerable electric vehicle, and calculating the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the tire model.

[0097] It is understood that the embodiments of this application can calculate the front wheel angle and rear wheel angle of a fully steerable electric vehicle during steering and braking by using a tire model lookup table. Here, the lookup table refers to the calculation and output by inputting a pre-defined table and using a certain interpolation algorithm.

[0098] As one possible implementation, embodiments of this application can calculate the vertical forces of the front and rear wheels of a fully steerable electric vehicle based on the lateral forces of the front and rear wheels and the deceleration of the fully steerable electric vehicle. When calculating the vertical forces of the front and rear wheels of the fully steerable electric vehicle, the calculation can be performed using formula (6) while meeting the deceleration requirements. Furthermore, the front and rear wheel steering angles during steering braking of the fully steerable electric vehicle can be calculated based on the tire model. The calculation results are as follows: Figure 4 As shown, the final optimized steering and braking angle is obtained, thereby improving vehicle stability.

[0099] Optionally, in one embodiment of this application, steering braking is at least one of the left wheel turning right and the right wheel turning left in a fully steerable electric vehicle.

[0100] It is understood that the steering braking in this embodiment of the application is that the two front wheels or two rear wheels of the car are actively steered to present an "inward" shape, that is, the left wheel turns to the right and the right wheel turns to the left, thereby producing a braking effect.

[0101] In actual implementation, the embodiments of this application can improve the stability and safety of vehicle operation by means of steering and braking, such as turning the left wheel of a fully steerable electric vehicle to the right and turning the right wheel to the left.

[0102] Specifically, it can be combined with Figure 5 and Figure 6 As shown, the working principle of the steering and braking angle distribution optimization method for a fully steerable electric vehicle in this application is explained in detail with a specific embodiment.

[0103] In this embodiment, the front wheel steering angle can be slightly larger than the rear wheel steering angle under a certain deceleration requirement. Based on the optimized front and rear wheel steering angle distribution, the simulation results of the front and rear wheel adhesion rates under different deceleration requirements are as follows: Figure 5 As shown. This application embodiment verifies through simulation that the front wheel adhesion rate and rear wheel adhesion rate are approximately equal in this embodiment. This means that, compared to the allocation algorithm where the front and rear wheel steering angles are the same, the optimization algorithm in this embodiment reduces the lateral force and adhesion rate of the rear wheels by decreasing the rear wheel steering angle. The resulting insufficient longitudinal braking force is compensated for by increasing the front wheel steering angle, thereby increasing the front wheel lateral force and adhesion rate. Thus, the front and rear wheels have approximately equal adhesion rates, improving vehicle stability.

[0104] like Figure 6 As shown, embodiments of this application may include the following steps:

[0105] Step S601: Define tire adhesion ratio.

[0106] Step S602: Calculate the lateral force of the front wheel and the lateral force of the rear wheel.

[0107] Step S603: Calculate the front wheel steering angle and the rear wheel steering angle.

[0108] The steering and braking angle allocation optimization method for fully steerable electric vehicles proposed in this application can optimize the allocation of the front and rear wheel steering angles of the fully steerable electric vehicle, making the front and rear wheel adhesion rates approximately equal, thereby improving vehicle stability. Furthermore, this application reasonably simplifies the solution process for optimizing the steering and braking angle allocation of fully steerable electric vehicles, offering advantages such as ease of implementation and strong versatility. This solves the problems in related technologies where, when the vehicle's drive and braking systems fail, it is difficult to perform redundant braking through the four-wheel independent steering system, reducing driving safety. Additionally, simply setting the front and rear wheel angles to be the same without reasonable allocation of the front and rear wheel angles reduces steering and braking stability.

[0109] Next, referring to the accompanying drawings, a steering and braking angle distribution optimization device for a fully drive-by-wire electric vehicle proposed according to an embodiment of this application is described.

[0110] Figure 7 This is a schematic diagram of the steering and braking angle distribution optimization device for a fully steerable electric vehicle according to an embodiment of this application.

[0111] like Figure 7 As shown, the steering and braking angle distribution optimization device 10 for the fully steerable electric vehicle includes: an acquisition module 100, a calculation module 200, and an optimization module 300.

[0112] Specifically, module 100 is used to acquire the user's deceleration requirements.

[0113] The calculation module 200 is used to calculate the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle by making the front wheel adhesion rate and rear wheel adhesion rate equal based on the deceleration requirement.

[0114] The optimization module 300 is used to calculate the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the lateral force of the front wheel and the lateral force of the rear wheel, the vertical force of the front wheel and the vertical force of the rear wheel, and the tire model, so as to optimize the allocation of the front wheel angle and the rear wheel angle and obtain the final optimized allocation result of the steering and braking angle.

[0115] Optionally, in one embodiment of this application, the steering and braking angle distribution optimization device 10 for a fully drive-by-wire electric vehicle further includes an acquisition module.

[0116] The acquisition module is used to obtain the tire adhesion rate of the fully steerable electric vehicle from the ratio of the actual tire force of the fully steerable electric vehicle to the maximum tire force of the fully steerable electric vehicle before making the front tire adhesion rate and the rear tire adhesion rate of the fully steerable electric vehicle equal.

[0117] Optionally, in one embodiment of this application, the calculation module 200 includes: a setup unit and a first calculation unit.

[0118] The unit is used to establish the first longitudinal dynamic equation of the fully steerable electric vehicle under the inward-pointing steering braking condition based on the deceleration requirements, and to obtain the second longitudinal dynamic equation based on the deceleration requirements and the first longitudinal dynamic equation.

[0119] The first calculation unit is used to make the front wheel adhesion rate and the rear wheel adhesion rate equal based on the second longitudinal dynamic equation, and to calculate the front wheel vertical force and the rear wheel vertical force of the fully steerable electric vehicle. It also calculates the front wheel lateral force and the rear wheel lateral force of the fully steerable electric vehicle based on the front wheel adhesion rate, the rear wheel adhesion rate, the front wheel vertical force, and the rear wheel vertical force.

[0120] Optionally, in one embodiment of this application, the first longitudinal dynamic equation is:

[0121] ,

[0122] in, For the longitudinal deceleration of fully drive-by-wire electric vehicles, ; For the longitudinal speed of fully line-controlled electric vehicles, ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively.

[0123] The second longitudinal dynamic equation is:

[0124] ,

[0125] in, For the longitudinal deceleration of fully drive-by-wire electric vehicles, ; For the longitudinal speed of fully line-controlled electric vehicles, ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. For the overall vehicle quality, It is the acceleration due to gravity. It is the acceleration due to gravity. For windward area, This refers to air density.

[0126] Optionally, in one embodiment of this application, the optimization module 300 includes a second computing unit.

[0127] The second calculation unit is used to calculate the vertical forces of the front and rear wheels of the fully steerable electric vehicle based on the lateral forces of the front and rear wheels and the deceleration of the fully steerable electric vehicle, and to calculate the front and rear wheel steering angles of the fully steerable electric vehicle during steering and braking based on the tire model.

[0128] Optionally, in one embodiment of this application, steering braking is at least one of the left wheel turning right and the right wheel turning left in a fully steerable electric vehicle.

[0129] It should be noted that the explanation of the aforementioned embodiment of the steering and braking angle distribution optimization method for fully steerable electric vehicles also applies to the steering and braking angle distribution optimization device for fully steerable electric vehicles in this embodiment, and will not be repeated here.

[0130] The steering and braking angle distribution optimization device for fully steerable electric vehicles proposed in this application can optimize the distribution of the front and rear wheel steering angles of a fully steerable electric vehicle, making the front and rear wheel adhesion rates approximately equal, thereby improving vehicle stability. Furthermore, this application reasonably simplifies the solution process for optimizing the steering and braking angle distribution of fully steerable electric vehicles, offering advantages such as ease of implementation and strong versatility. This solves the problems in related technologies where, when the vehicle's drive and braking systems fail, it is difficult to perform redundant braking through the four-wheel independent steering system, reducing driving safety. Additionally, simply setting the front and rear wheel angles to be the same without reasonable distribution of the front and rear wheel angles reduces steering and braking stability.

[0131] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0132] The memory 801, the processor 802, and the computer program stored on the memory 801 and capable of running on the processor 802.

[0133] When the processor 802 executes the program, it implements the steering and braking angle distribution optimization method for the fully drive-by-wire electric vehicle provided in the above embodiments.

[0134] Furthermore, electronic devices also include:

[0135] Communication interface 803 is used for communication between memory 801 and processor 802.

[0136] The memory 801 is used to store computer programs that can run on the processor 802.

[0137] The memory 801 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0138] If the memory 801, processor 802, and communication interface 803 are implemented independently, then the communication interface 803, memory 801, and processor 802 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized into address buses, data buses, control buses, etc. For ease of representation, Figure 8 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0139] Optionally, in a specific implementation, if the memory 801, processor 802, and communication interface 803 are integrated on a single chip, then the memory 801, processor 802, and communication interface 803 can communicate with each other through an internal interface.

[0140] The processor 802 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0141] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle.

[0142] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0144] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0145] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0146] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0147] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0148] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0149] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for optimizing the steering and braking angle distribution of a fully steerable electric vehicle, characterized in that, Includes the following steps: Obtain the user's deceleration requirements; Based on the aforementioned deceleration requirement, the front and rear wheel adhesion rates of the fully steerable electric vehicle are made equal, and the front and rear wheel lateral forces of the fully steerable electric vehicle are calculated under preset conditions; and Based on the lateral forces of the front and rear wheels, the vertical forces of the front and rear wheels, and the tire model, the front wheel and rear wheel steering angles during steering and braking of the fully steerable electric vehicle are calculated to optimize the allocation of the front wheel and rear wheel steering angles, thus obtaining the final optimized allocation result of the steering and braking angles.

2. The method according to claim 1, characterized in that, Before ensuring that the front and rear wheel adhesion rates of a fully drive-by-wire electric vehicle are equal, the following steps are also included: The tire adhesion rate of the fully steerable electric vehicle is obtained by the ratio of the actual tire force to the maximum tire force of the fully steerable electric vehicle.

3. The method according to claim 1, characterized in that, The step of ensuring equal front and rear wheel adhesion rates for the fully steerable electric vehicle based on the deceleration requirement, and calculating the front and rear wheel lateral forces under preset conditions, includes: Based on the aforementioned deceleration requirement, under the inward-pointing steering braking condition, the first longitudinal dynamic equation of the fully steerable electric vehicle is established, and the second longitudinal dynamic equation is obtained based on the aforementioned deceleration requirement and the first longitudinal dynamic equation. Based on the second longitudinal dynamic equation, the front wheel adhesion rate and the rear wheel adhesion rate are made equal, and the vertical force of the front wheel and the vertical force of the rear wheel of the fully steerable electric vehicle are calculated. Under the preset conditions, the lateral force of the front wheel and the lateral force of the rear wheel of the fully steerable electric vehicle are calculated according to the front wheel adhesion rate, the rear wheel adhesion rate, the vertical force of the front wheel and the vertical force of the rear wheel.

4. The method according to claim 3, characterized in that, The first longitudinal dynamic equation is: ， in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. The second longitudinal dynamic equation is: ， in, Let be the longitudinal deceleration of the fully drive-by-wire electric vehicle. ; Let be the longitudinal speed of the fully drive-by-wire electric vehicle. ; For the turning angle of the wheel, The subscripts f and r represent the front and rear wheels, respectively. For the overall vehicle quality, It is the acceleration due to gravity. It is the acceleration due to gravity. For windward area, This refers to air density.

5. The method according to claim 1, characterized in that, The calculation of the front wheel and rear wheel steering angles during steering and braking of the fully steerable electric vehicle based on the front wheel lateral force, the rear wheel lateral force, the front wheel vertical force, the rear wheel vertical force, and the tire model includes: The vertical forces of the front and rear wheels of the fully steerable electric vehicle are calculated based on the lateral forces of the front and rear wheels and the deceleration of the fully steerable electric vehicle. The steering angles of the front and rear wheels during steering and braking of the fully steerable electric vehicle are also calculated based on the tire model.

6. The method according to claim 1, characterized in that, The steering braking is at least one of the following: the left wheel of the fully drive-by-wire electric vehicle turns right and the right wheel turns left.

7. A steering and braking angle distribution optimization device for a fully steerable electric vehicle, characterized in that, include: The acquisition module is used to acquire the user's deceleration requirements; The calculation module is used to make the front wheel adhesion rate and rear wheel adhesion rate of the fully steerable electric vehicle equal based on the deceleration requirement, and to calculate the front wheel lateral force and rear wheel lateral force of the fully steerable electric vehicle under preset conditions. as well as The optimization module is used to calculate the front wheel angle and rear wheel angle during steering and braking of the fully steerable electric vehicle based on the front wheel lateral force, the rear wheel lateral force, the front wheel vertical force, the rear wheel vertical force, and the tire model, so as to optimize the allocation of the front wheel angle and the rear wheel angle and obtain the final optimized allocation result of the steering and braking angle.

8. The apparatus according to claim 7, characterized in that, Also includes: The acquisition module is used to obtain the tire adhesion rate of the fully steerable electric vehicle from the ratio of the actual tire force of the fully steerable electric vehicle to the maximum tire force of the fully steerable electric vehicle before making the front tire adhesion rate and the rear tire adhesion rate equal.

9. An electronic device, characterized in that, include: The memory, the processor, and the computer program stored in the memory and executable on the processor, the processor executing the program to implement the steering and braking angle distribution optimization method for a fully steerable electric vehicle as described in any one of claims 1-6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the steering and braking angle distribution optimization method for a fully steerable electric vehicle as described in any one of claims 1-6.

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