Drive force distribution method for vehicles

Abstract

This application discloses a method for distributing driving force in a vehicle. The method includes the following steps: acquiring multiple input parameters; calculating multiple membership functions corresponding to the multiple input parameters; determining a driving force distribution ratio using a preset model based on the multiple membership functions, wherein the driving force distribution ratio is the proportion of the driving force allocated to the vehicle's auxiliary drive shaft to the total vehicle driving force; and distributing the vehicle driving force according to the driving force distribution ratio. This application also discloses a control device for distributing vehicle driving force and a computer program.

Description

Technical Field

[0001] This application relates to the field of motor vehicle control, specifically to a method for distributing driving force in a vehicle. This application also relates to a control device for distributing driving force in a vehicle and a computer program article. Background Technology

[0002] With the development of automotive technology, people have increasingly higher requirements for various performance aspects of automobiles, such as power, handling stability, and safety. Four-wheel drive technology, because it can fully utilize the traction of the wheels to obtain the greatest possible driving force, is increasingly being adopted by high-end sedans and sports cars.

[0003] In four-wheel drive vehicles, inter-axle torque distribution control technology is a key technology for steering. By controlling the torque distribution between the front and rear axles and between the left and right wheels, optimal traction performance of the drive wheels is achieved, allowing the vehicle to fully utilize ground adhesion. This enables the vehicle to adapt to constantly changing driving conditions and road surfaces, rationally distributing driving torque to each drive wheel to maximize the driving force of each tire. The controlled wheels obtain greater longitudinal and lateral adhesion, but it is essential to ensure good road adhesion conditions for each drive wheel after torque redistribution. This improves the vehicle's traction, directional stability, and steering handling. Currently, common methods for distributing vehicle driving force between wheels include the following.

[0004] The first method is the one-dimensional control method. In this method, the vehicle's driving force is first calculated using the engine's output torque and the current gear of the transmission, and then the driving force is proportionally distributed to each wheel. The drawback of the one-dimensional control method is that it fails for vehicles in dynamic driving conditions (such as off-road driving). This is because the one-dimensional control method requires a vehicle in steady-state driving to achieve the theoretically optimal driving force distribution. In a dynamically driving vehicle, the accelerator pedal position and vehicle speed are constantly changing, causing the vehicle's center of gravity to shift irregularly forward or backward, resulting in a dynamic change in the required ratio of driving force between the front and rear wheels.

[0005] The second method is the multidimensional serial control method. In this method, factors such as vehicle driving force, steering wheel angle, vehicle posture, and wheel speeds are considered in stages. It starts with the vehicle driving force, then gradually introduces the influence of steering wheel angle, vehicle posture, and wheel speeds, correcting the driving force distribution ratio in stages to ultimately obtain the desired ratio. The drawback of the multidimensional serial control method is that it considers only one isolated influencing factor in each correction stage, making the correction process prone to illogical operations. For example, at different vehicle speeds, the same steering wheel operation by the driver will result in significant differences in the vehicle's lateral acceleration (i.e., vehicle posture). In other words, the higher the vehicle speed, the greater the lateral acceleration caused by the same steering wheel operation. Therefore, if the influence of vehicle speed is not considered when correcting the driving force distribution ratio based on lateral acceleration, there will be a significant deviation between the calculated desired driving force distribution ratio and the actual required ratio.

[0006] The third method is multidimensional parallel control. In multidimensional parallel control, factors such as vehicle driving force, steering wheel angle, vehicle posture, and wheel speeds are considered simultaneously to comprehensively adjust the driving force distribution ratio, ultimately obtaining the desired driving force distribution ratio. The disadvantage of multidimensional parallel control is that it generates a huge demand on controller memory when there are many input dimensions. For example, considering twenty cases for N-dimensional inputs, the required number of memory function blocks would be 20. N As the number of input dimensions increases, the required storage space increases exponentially. Summary of the Invention

[0007] In view of the shortcomings of the above methods, it is desirable to develop a method for distributing vehicle driving force (also referred to as vehicle driving torque in this application). The method is applicable to dynamically moving vehicles, and takes into account factors such as vehicle driving force, steering wheel angle, vehicle posture and four-wheel speed, and comprehensively corrects the driving force distribution ratio, while requiring less storage space.

[0008] This application provides a method for distributing driving force in a vehicle. The method includes the following steps: acquiring multiple input parameters; calculating multiple membership functions corresponding to the multiple input parameters; determining a driving force distribution ratio using a preset model based on the multiple membership functions, wherein the driving force distribution ratio is the proportion of the driving force allocated to the auxiliary drive shaft of the vehicle to the total driving force of the vehicle; and distributing the driving force of the vehicle according to the driving force distribution ratio.

[0009] According to an optional implementation, multiple input parameters include: vehicle driving force, steering wheel angle, vehicle posture sensor values, and four-wheel wheel speed difference.

[0010] According to an optional implementation, the vehicle attitude sensor values ​​include the vehicle's longitudinal acceleration, lateral acceleration, and yaw rate.

[0011] According to an optional implementation, the four-wheel wheel speed difference includes the maximum value of the numerical difference between every two wheels of the vehicle's four wheels acquired at the same time.

[0012] According to an optional implementation, in the step of calculating multiple membership functions corresponding to multiple input parameters: the vehicle driving force is divided into four intervals: coasting interval, low torque interval, medium torque interval, and high torque interval; the steering wheel angle is divided into four intervals: initial angle interval, small angle interval, medium angle interval, and large angle interval; the four-wheel wheel speed difference is divided into three intervals: small difference interval, medium difference interval, and large difference interval; and the longitudinal acceleration is divided into three intervals: braking condition interval, steady-state condition interval, and acceleration condition interval.

[0013] According to an optional implementation, in the step of determining the driving force distribution ratio using a preset model, the vehicle driving force and steering wheel angle are first considered. Specifically, when the vehicle driving force is in the coasting range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be a medium torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. When the vehicle driving force is in the coasting range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be a low torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. When the vehicle driving force is in the low torque range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be a medium torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. When the vehicle driving force is in the low torque range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be a medium torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. In any given range, the drive force distribution ratio is set to a low torque ratio. When the vehicle's drive force is in the medium torque range and the steering wheel angle is in the initial angle range, the drive force distribution ratio is set to a high torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. When the vehicle's drive force is in the medium torque range and the steering wheel angle is in the small, medium, or large angle range, the drive force distribution ratio is set to a low torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. When the vehicle's drive force is in the high torque range and the steering wheel angle is in the initial angle range, the drive force distribution ratio is set to the maximum torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration. And when the vehicle's drive force is in the high torque range and the steering wheel angle is in the small, medium, or large angle range, the drive force distribution ratio is set to a medium torque ratio regardless of the range of the four-wheel speed difference and longitudinal acceleration.

[0014] According to an optional implementation, in the step of determining the driving force distribution ratio using a preset model, the wheel speed difference of the four wheels is first considered. Specifically, when the wheel speed difference of the four wheels is in the middle range, the driving force distribution ratio is determined to be the high torque ratio regardless of the range of vehicle driving force, steering wheel angle, and longitudinal acceleration. And when the wheel speed difference of the four wheels is in the large range, the driving force distribution ratio is determined to be the maximum torque ratio regardless of the range of vehicle driving force, steering wheel angle, and longitudinal acceleration.

[0015] According to an optional implementation, in the step of determining the driving force distribution ratio using a preset model, longitudinal acceleration is considered first. Specifically, when the longitudinal acceleration is within the braking condition range, the driving force distribution ratio is determined to be a medium torque ratio regardless of the range of vehicle driving force, steering wheel angle, and four-wheel speed difference; when the longitudinal acceleration is within the steady-state condition range, the driving force distribution ratio is determined to be a low torque ratio regardless of the range of vehicle driving force, steering wheel angle, and four-wheel speed difference; and when the longitudinal acceleration is within the acceleration condition range, the driving force distribution ratio is determined to be a medium torque ratio regardless of the range of vehicle driving force, steering wheel angle, and four-wheel speed difference.

[0016] This application also provides a control device for distributing vehicle driving force, comprising: an inter-axle differential installed between the front and rear drive axles of the vehicle for distributing driving force between the front and rear drive axles; a hydraulic brake installed at the wheel hubs of each wheel of the vehicle for braking the outer front wheel or inner rear wheel to generate additional yaw moment when required for operation; an electronic control unit installed near the engine of the vehicle for analyzing, judging, calculating, and processing various signals collected by sensors, and generating signals to control the inter-axle differential and the hydraulic brake to execute system actions; wheel speed sensors installed on the wheel hubs of each wheel of the vehicle for monitoring wheel speed signals; and a steering wheel angle sensor installed below the steering wheel of the vehicle. The system includes: a steering wheel angle sensor for monitoring the steering wheel angle; a vehicle speed sensor installed in the transmission housing for monitoring the vehicle's longitudinal speed; and a longitudinal acceleration sensor installed under the center console for monitoring the vehicle's longitudinal acceleration, lateral acceleration, and yaw rate. The wheel speed sensor, vehicle speed sensor, longitudinal acceleration sensor, and steering wheel angle sensor are connected to the input of the electronic control unit (ECU), while the inter-axle differential and hydraulic brakes are connected to the output of the ECU. The ECU includes a memory, a processor, and a computer program artifact stored in the memory. The computer program artifact includes program code configured to, when executed on the processor, cause the processor to perform the drive force distribution method for a vehicle according to this document.

[0017] This application also provides a computer program article comprising program code configured to, when run on a computer, cause the computer to perform the drive force distribution method for a vehicle according to this document.

[0018] The driving force distribution method for vehicles according to this application comprehensively considers vehicle driving force, steering wheel angle, vehicle attitude sensor values ​​(represented by longitudinal acceleration), and four-wheel wheel speed differences. These four variables are used as four-dimensional inputs to the algorithm, and a fuzzy algorithm is applied to derive a reasonable driving force distribution ratio. These four variables cover various vehicle driving states and driver intentions. Therefore, the driving force distribution method for vehicles according to this application is applicable to dynamically moving vehicles, comprehensively balancing factors such as vehicle driving force, steering wheel angle, vehicle attitude, and four-wheel wheel speeds to correct the driving force distribution ratio, while requiring relatively little storage space. Attached Figure Description

[0019] A more complete understanding of the foregoing and other aspects of this application will be gained from the detailed description that follows, in conjunction with the accompanying drawings. It should be noted that the scale of the drawings may vary for clarity, but this will not affect the understanding of this application. In the drawings:

[0020] Figure 1 A schematic diagram of a control device for distributing vehicle driving force according to this application is shown;

[0021] Figure 2 Show Figure 1 An enlarged schematic diagram of the electronic control unit of the control device;

[0022] Figure 3 A flowchart illustrating a drive force distribution method for a vehicle according to this application is shown;

[0023] Figure 4 A graph showing the relationship between vehicle driving force, steering wheel angle, and driving force distribution ratio in a preset model;

[0024] Figure 5 A graph showing the relationship between vehicle driving force, longitudinal acceleration, and driving force distribution ratio in a preset model;

[0025] Figure 6 A graph showing the relationship between vehicle driving force, four-wheel speed difference, and driving force distribution ratio in a preset model;

[0026] Figure 7 A graph showing the relationship between steering wheel angle, longitudinal acceleration, and driving force distribution ratio in a preset model;

[0027] Figure 8 A graph showing the relationship between steering wheel angle, wheel speed difference, and drive force distribution ratio in a preset model; and

[0028] Figure 9A graph showing the relationship between longitudinal acceleration, wheel speed difference of the four wheels, and driving force distribution ratio in a preset model. Detailed Implementation

[0029] In the accompanying drawings of this application, features with the same structure or similar function are indicated by the same reference numerals.

[0030] Figure 1 A schematic diagram of a control device for distributing vehicle driving force according to this application is shown. The control device includes an electronic control unit (ECU) 1, wheel speed sensors 2, steering wheel angle sensors 3, vehicle speed sensors 4, hydraulic brakes 5, longitudinal acceleration sensors 6, and an inter-axle differential 7. Wheel speed sensors 2, vehicle speed sensors 4, longitudinal acceleration sensors 6, and steering wheel angle sensors 3 are all connected to the input terminals of the ECU 1, while the inter-axle differential 7 and hydraulic brakes 5 are both connected to the output terminals of the ECU 1.

[0031] ECU 1 is installed near the engine 15 of vehicle 11. It analyzes, judges, calculates, and processes various signals collected by sensors, and generates signals to control the inter-axle differential 7 and hydraulic brake 5 to execute system actions, thereby ensuring vehicle steering safety and handling stability. Wheel speed sensors 2 are installed on the hubs of each wheel 14 of vehicle 11 to monitor wheel speed signals. Steering wheel angle sensor 3 is installed in the steering column below the steering wheel 16 of vehicle 11 to monitor the steering wheel angle. Vehicle speed sensor 4 is installed in the housing of the transmission 17 of vehicle 11 to monitor the vehicle's longitudinal speed. Vehicle attitude sensor 6 is installed under the armrest box of vehicle 11 to monitor the vehicle's longitudinal acceleration, lateral acceleration, and yaw rate. Inter-axle differential 7 is installed between the front drive axle 12 and the rear drive axle 13 of vehicle 11 to distribute driving force between them. Hydraulic brakes 5 are installed at the hubs of each wheel 14 of the vehicle 11. They are used to brake the outer front wheel or the inner rear wheel when needed to generate additional yaw moment and ensure the vehicle's steering stability.

[0032] Figure 2 Show Figure 1 An enlarged schematic diagram of the electronic control unit (ECU) of the control device. ECU 1 includes a memory 10, a processor 20, and a computer program article 30 stored on the memory 10. The computer program article 30 includes program code configured to, when executed on the processor 20, cause the processor 20 to execute the drive force distribution method for a vehicle according to this application.

[0033] Figure 3The present application illustrates a method for distributing driving force for a vehicle, comprising the following steps: 101: acquiring multiple input parameters; 102: calculating multiple membership functions corresponding to the multiple input parameters; 103: determining a driving force distribution ratio using a preset model based on the multiple membership functions, wherein the driving force distribution ratio is the proportion of the driving force distributed to the secondary drive shaft of the vehicle to the total driving force of the vehicle; and 104: distributing the driving force of the vehicle according to the driving force distribution ratio.

[0034] Membership functions are related to the concept of fuzzy control systems. Fuzzy control systems transform clear, quantitative numerical inputs into qualitative, factual inputs. The qualitative factual inputs define their own factuality through values ​​between 0 and 1 (i.e., membership functions). This process is called fuzzification. The qualitative factual inputs, through comprehensive evaluation using fuzzy rules, form one or more qualitative outputs (also called fuzzy outputs). Finally, the qualitative outputs are transformed into one or more clear, quantitative numerical outputs through an inverse fuzzification process. The fuzzification algorithm used in this paper employs a MIN-MAX interaction mechanism. In the MIN-MAX interaction mechanism, the AND operation uses the MIN operator, and the OR operation uses the MAX operator. The inverse fuzzification process used in this paper employs the centroid method for calculation, as shown in the following equation:

[0035]

[0036] This section uses an example to illustrate the fuzzification algorithm. Assume the fuzzification algorithm has two rules:

[0037] IF T=low AND P=large THEN y=middle

[0038] IF T=middle AND P=large THEN y=small

[0039] First, the two quantitative numerical inputs (T0, P0) are fuzzified. This yields the corresponding qualitative truth values, ω1 (T = ..., P = ...) and ω2 (T = ..., P = ...). Then, the activity factor (μ) of the corresponding rule can be obtained. B1 μ B2 By summing the activity factors of each rule, the final weight factor μ can be obtained. res Finally, the inverse fuzzification process can be completed using the centroid method to obtain the final quantitative value.

[0040] Here, we'll further explain defuzzification and the centroid method with an example. For instance, dividing the range of vehicle driving force might result in "medium torque (25%), high torque (80%)". Defuzzification converts this information into a specific decision or real value. The simplest (but least practical) way to defuzzify is to take the result with the highest degree of dependence. In this example, high torque has an 80% degree of dependence, so other choices can be omitted, and 80% can be converted into a physical quantity. The problem with this method is the loss of a lot of information; in this example, the possibility of medium torque is mentioned, but it cannot be reflected in the result. In the centroid method, the results of each rule are first added together in some way. The most common graph of the fuzzy set dependence function is a triangle with a pointed top and a flat bottom. If the triangle is cut by a horizontal line, only the lower part of the graph is retained, resulting in a trapezoid. The first step of defuzzification is to cut off a portion of each dependence function, retaining the trapezoid (if the original dependence function is not a triangle, the remaining shape after cutting may be different). In this example, the output is medium torque (25%), so the graph of the dependent function corresponding to medium torque (25%) needs to have more than 25% of it removed. Then, the dependent functions are superimposed to form a single geometric shape, and the geometric center of this shape is calculated; this is called the fuzzy center. The x-coordinate of the fuzzy center is the value of the defuzzification.

[0041] Returning to the driving force distribution method for a vehicle in this application, the multiple input parameters (i.e., quantitative numerical inputs) may include: vehicle driving force, steering wheel angle, vehicle attitude sensor values, and four-wheel wheel speed differences. Vehicle attitude sensor values ​​may include the vehicle's longitudinal acceleration, lateral acceleration, and yaw rate. The four-wheel wheel speed differences include the maximum value of the numerical differences between any two wheels of the vehicle's four wheels acquired simultaneously.

[0042] In the step of calculating multiple membership functions corresponding to the multiple input parameters: the vehicle driving force is divided into four intervals (i.e., qualitative truth inputs): coasting interval, low torque interval, medium torque interval, and high torque interval; the steering wheel angle is divided into four intervals: initial angle interval, small angle interval, medium angle interval, and large angle interval; the four-wheel wheel speed difference is divided into three intervals: small difference interval, medium difference interval, and large difference interval; and the longitudinal acceleration is divided into three intervals: braking condition interval, steady-state condition interval, and acceleration condition interval.

[0043] In this application, the membership function of the coasting range of the vehicle driving force decreases from 1 to 0 as the vehicle driving force increases from 0 Nm to 300 Nm; the membership function of the low torque range of the vehicle driving force increases from 0 to 1 and then decreases to 0 as the vehicle driving force increases from 100 Nm to 600 Nm; the membership function of the medium torque range of the vehicle driving force increases from 0 to 1 and then decreases to 0 as the vehicle driving force increases from 500 Nm to 1500 Nm; and the membership function of the high torque range of the vehicle driving force increases from 0 to 1 as the vehicle driving force increases from 1300 Nm to 5000 Nm.

[0044] In this application, the membership function of the initial steering wheel angle interval decreases from 1 to 0 as the steering wheel angle increases from 0° to 30°; the membership function of the small steering wheel angle interval increases from 0 to 1 and then decreases to 0 as the steering wheel angle increases from 10° to 90°; the membership function of the medium steering wheel angle interval increases from 0 to 1 and then decreases to 0 as the steering wheel angle increases from 60° to 150°; and the membership function of the large steering wheel angle interval increases from 0 to 1 as the steering wheel angle increases from 90° to 700°.

[0045] In this application, the membership function of the small difference interval of the four-wheel wheel speed difference decreases from 1 to 0 as the four-wheel wheel speed difference increases from 0 m / s to 4 m / s; the membership function of the medium difference interval of the four-wheel wheel speed difference increases from 0 to 1 and then decreases to 0 as the four-wheel wheel speed difference increases from 2 m / s to 8 m / s; and the membership function of the large difference interval of the four-wheel wheel speed difference increases from 0 to 1 as the four-wheel wheel speed difference increases from 6 m / s to 20 m / s.

[0046] In this application, the membership function of the braking condition range of longitudinal acceleration is defined as follows: longitudinal acceleration from -2 m / s² 2 Increased to -0.2 m / s 2 During the process, it decreases from 1 to 0; the membership function of the longitudinal acceleration in the steady-state operating range decreases as the longitudinal acceleration decreases from -0.4 m / s². 2 Increased to 0.4 m / s 2 During the process, the acceleration increases from 0 to 1 and then decreases back to 0; while the membership function of the longitudinal acceleration in the acceleration range increases from 0.2 to 2 m / s². 2 It increases from 0 to 1 during the process.

[0047] For various combinations of qualitative reality inputs, the corresponding qualitative outputs are determined. The four qualitative reality inputs—vehicle driving force, steering wheel angle, longitudinal acceleration, and four-wheel speed difference—are combined pairwise without regard to order, resulting in a total of six combinations. These six combinations are summarized in the table below.

[0048] Vehicle driving force Steering wheel angle longitudinal acceleration Four-wheel speed difference Torque distribution ratio slide initial state - - Medium torque slide Non-initial state - - low torque Low initial state - - Medium torque Low Non-initial state - - low torque middle initial state - - High torque middle Non-initial state - - low torque high initial state - - Maximum torque high Non-initial state - - Medium torque

[0049] Table 1 shows the torque distribution ratios considering vehicle driving force and steering wheel angle.

[0050]

[0051]

[0052] Table 2 shows the torque distribution ratios considering the wheel speed differences of the four wheels.

[0053] Vehicle driving force Steering wheel angle longitudinal acceleration Four-wheel speed difference Torque distribution ratio - - brake - Medium torque - - steady state - low torque - - accelerate - Medium torque

[0054] Table 3 Torque distribution ratio considering longitudinal acceleration first.

[0055] In this application, "low torque ratio" can be a drive force distribution ratio in the range of 0% to 9%; "medium torque ratio" can be a drive force distribution ratio in the range of 15% to 25%; "high torque ratio" can be a drive force distribution ratio in the range of 25% to 35%; and "maximum torque ratio" can be a drive force distribution ratio in the range of 35% to 45%. It should be noted that other drive force distribution ratios are also feasible and are included within the scope of this application.

[0056] Figure 4 A graph showing the relationship between vehicle driving force, steering wheel angle, and driving force distribution ratio in a preset model. Figure 5 A graph showing the relationship between vehicle driving force, longitudinal acceleration, and driving force distribution ratio in a preset model. Figure 6 A graph showing the correspondence between vehicle driving force, four-wheel wheel speed difference, and driving force distribution ratio in a preset model. According to... Figures 4-6According to Table 1, considering vehicle driving force and steering wheel angle, the effects of longitudinal acceleration and the four-wheel speed difference on the driving force distribution ratio can be ignored. When the vehicle driving force is in the coasting range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be a medium torque ratio. When the vehicle driving force is in the coasting range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be a low torque ratio. When the vehicle driving force is in the low torque range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be a medium torque ratio. When the vehicle driving force is in the low torque range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be a low torque ratio. When the vehicle driving force is in the medium torque range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be a high torque ratio. When the vehicle's driving force is in the medium torque range and the steering wheel angle is in the small, medium, or large steering angle range, the driving force distribution ratio is determined to be the low torque ratio. When the vehicle's driving force is in the high torque range and the steering wheel angle is in the initial steering angle range, the driving force distribution ratio is determined to be the maximum torque ratio. When the vehicle's driving force is in the high torque range and the steering wheel angle is in the small, medium, or large steering angle range, the driving force distribution ratio is determined to be the medium torque ratio.

[0057] Figure 7 A graph showing the relationship between steering wheel angle, longitudinal acceleration, and drive force distribution ratio in a preset model. Figure 8 A graph showing the correspondence between steering wheel angle, four-wheel speed difference, and drive force distribution ratio in a preset model. According to... Figures 7-8 According to Table 2, considering the wheel speed difference of the four wheels first, the influence of vehicle driving force and longitudinal acceleration on the driving force distribution ratio can be ignored. When the wheel speed difference of the four wheels is in the medium range, the driving force distribution ratio is determined to be the high torque ratio. When the wheel speed difference of the four wheels is in the large range, the driving force distribution ratio is determined to be the maximum torque ratio.

[0058] Figure 9 A graph showing the relationship between longitudinal acceleration, four-wheel speed difference, and drive force distribution ratio in a preset model. According to Figure 9According to Table 3, considering longitudinal acceleration first, the influence of vehicle driving force and the difference in wheel speeds of the four wheels on the driving force distribution ratio can be ignored. When the longitudinal acceleration is within the braking range, the driving force distribution ratio is determined to be a medium torque ratio. When the longitudinal acceleration is within the steady-state range, the driving force distribution ratio is determined to be a low torque ratio. When the longitudinal acceleration is within the acceleration range, the driving force distribution ratio is determined to be a medium torque ratio.

[0059] The driving force distribution method for vehicles according to this application comprehensively considers vehicle driving force, steering wheel angle, vehicle attitude sensor values ​​(represented by longitudinal acceleration), and four-wheel wheel speed differences. These four variables are used as four-dimensional inputs to the algorithm, and a fuzzy algorithm is applied to derive a reasonable driving force distribution ratio. These four variables cover various vehicle driving states and driver intentions. Therefore, the driving force distribution method for vehicles according to this application is applicable to dynamically moving vehicles, comprehensively balancing factors such as vehicle driving force, steering wheel angle, vehicle attitude, and four-wheel wheel speeds to correct the driving force distribution ratio, while requiring relatively little storage space.

[0060] Although specific embodiments of this application are described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of this application. Various substitutions, modifications, and alterations can be conceived without departing from the spirit and scope of this application.

Claims

1. A method for distributing driving force in a vehicle, the method comprising the following steps: Acquire (101) multiple input parameters; the multiple input parameters include: vehicle driving force, steering wheel angle, vehicle posture sensor value and four-wheel wheel speed difference; the vehicle posture sensor value includes the vehicle's longitudinal acceleration, lateral acceleration and yaw rate; Calculate (102) multiple membership functions corresponding to the multiple input parameters; Based on the multiple membership functions, a preset model is used to determine the (103) driving force distribution ratio, wherein the driving force distribution ratio is the proportion of the driving force allocated to the vehicle's auxiliary drive shaft to the total driving force of the vehicle; and The vehicle driving force is distributed (104) according to the driving force distribution ratio; In the step of calculating (102) multiple membership functions corresponding to the multiple input parameters: The vehicle driving force is divided into four intervals: coasting interval, low torque interval, medium torque interval, and high torque interval; the steering wheel angle is divided into four intervals: initial angle interval, small angle interval, medium angle interval, and large angle interval; the four-wheel wheel speed difference is divided into three intervals: small difference interval, medium difference interval, and large difference interval; and the longitudinal acceleration is divided into three intervals: braking condition interval, steady-state condition interval, and acceleration condition interval.

2. The driving force distribution method according to claim 1, wherein: The four-wheel speed difference includes the maximum value of the numerical difference between any two wheels of the vehicle's four wheels acquired at the same time.

3. The driving force distribution method according to claim 1, wherein, In the step of determining the driving force distribution ratio (103) using a preset model, the vehicle driving force and the steering wheel angle are first considered, and wherein, When the vehicle driving force is in the coasting range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be the medium torque ratio, regardless of which range the four-wheel speed difference and the longitudinal acceleration are in. When the vehicle driving force is in the coasting range and the steering wheel angle is in the small angle range, medium angle range or large angle range, the driving force distribution ratio is determined to be a low torque ratio regardless of the range of the four-wheel speed difference and the longitudinal acceleration. When the vehicle driving force is in the low torque range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be the medium torque ratio, regardless of the range of the four-wheel speed difference and the longitudinal acceleration. When the vehicle driving force is in the low torque range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be the low torque ratio regardless of the range of the four-wheel speed difference and the longitudinal acceleration. When the vehicle driving force is in the medium torque range and the steering wheel angle is in the initial angle range, the driving force distribution ratio is determined to be the high torque ratio regardless of the range of the four-wheel speed difference and the longitudinal acceleration. When the vehicle driving force is in the medium torque range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be a low torque ratio regardless of the range of the four-wheel speed difference and the longitudinal acceleration. When the vehicle driving force is in the high torque range and the steering wheel angle is in the initial angle range, regardless of the range of the four-wheel speed difference and the longitudinal acceleration, the driving force distribution ratio is determined to be the maximum torque ratio; and When the vehicle driving force is in the high torque range and the steering wheel angle is in the small, medium, or large angle range, the driving force distribution ratio is determined to be the medium torque ratio, regardless of the range of the four-wheel speed difference and the longitudinal acceleration.

4. The driving force distribution method according to claim 1, wherein, In the step of determining the driving force distribution ratio (103) using a preset model, the wheel speed difference of the four wheels is first considered, and wherein, When the wheel speed difference between the four wheels is within the middle range, regardless of the range of the vehicle driving force, the steering wheel angle, and the longitudinal acceleration, the driving force distribution ratio is determined to be a high torque ratio; and When the wheel speed difference of the four wheels is in a large difference range, the driving force distribution ratio is determined to be the maximum torque ratio, regardless of the range of the vehicle driving force, the steering wheel angle and the longitudinal acceleration.

5. The driving force distribution method according to claim 1, wherein, In the step of determining the driving force distribution ratio (103) using a preset model, the longitudinal acceleration is first considered, and wherein, When the longitudinal acceleration is within the braking condition range, regardless of the range of the vehicle driving force, the steering wheel angle, and the four-wheel wheel speed difference, the driving force distribution ratio is determined to be the medium torque ratio. When the longitudinal acceleration is within the steady-state operating range, regardless of the range of the vehicle driving force, the steering wheel angle, and the four-wheel wheel speed difference, the driving force distribution ratio is determined to be a low torque ratio; and When the longitudinal acceleration is in the acceleration range, regardless of the range of the vehicle driving force, the steering wheel angle, and the four-wheel speed difference, the driving force distribution ratio is determined to be the medium torque ratio.

6. A control device for distributing vehicle driving force, comprising: An inter-axle differential (7) is installed between the front drive axle (12) and the rear drive axle (13) of the vehicle (11) for distributing driving force between the front drive axle (12) and the rear drive axle (13). Hydraulic brakes (5) are installed at the hubs of each wheel (14) of the vehicle (11) to brake the outer front wheel or inner rear wheel of the vehicle (11) when work is required to generate additional yaw moment. The electronic control unit (1), which is installed near the engine (15) of the vehicle (11), is used to analyze, judge, calculate and process various signals collected by the sensors, and generate signals to control the inter-axle differential (7) and the hydraulic brake (5) to perform the actions of the system. Wheel speed sensor (2), which is installed on the hub of each wheel (14) of the vehicle (11), is used to monitor wheel speed signals; A steering wheel angle sensor (3) is installed in the steering column below the steering wheel (16) of the vehicle (11) to monitor the steering wheel angle; A vehicle speed sensor (4) is installed in the housing of the transmission (17) of the vehicle (11) to monitor the longitudinal speed of the vehicle. A longitudinal acceleration sensor (6) is installed under the armrest box of the vehicle (11) to monitor the longitudinal acceleration, lateral acceleration and yaw rate of the vehicle; Among them, the wheel speed sensor (2), the vehicle speed sensor (4), the longitudinal acceleration sensor (6), and the steering wheel angle sensor (3) are connected to the input terminal of the electronic control unit (1), while the inter-axle differential (7) and the hydraulic brake (5) are connected to the output terminal of the electronic control unit 1; and The electronic control unit (1) includes a memory (10), a processor (20), and a computer program article (30) stored in the memory (10). The computer program article (30) includes program code configured to, when run on the processor (20), cause the processor (20) to perform a drive force distribution method for a vehicle according to any one of claims 1-5.

7. A computer program article (30) comprising program code configured to, when run on a computer, cause the computer to perform a drive force distribution method for a vehicle according to any one of claims 1-5.

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