A method for controlling vehicle tire driving force under extreme road conditions

Abstract

A method for controlling the driving force of a vehicle tire under extreme road conditions belongs to the field of vehicle control technology and comprises the following steps: constructing a mechanical model of a tire and a road surface by using discrete element simulation software, and simulating and obtaining the relationship between longitudinal slip force and slip rate under different road soil conditions; determining the longitudinal slip force peak point and its corresponding slip rate under various road conditions; judging the road type, taking the longitudinal slip force peak point as a tracking point, and changing the current slip rate so that the vehicle obtains the maximum longitudinal slip force when slipping or about to slip, thereby improving the vehicle's escape and passing capabilities.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a tire driving force control method under extreme road conditions. Background Art

[0002] When a vehicle is driving on extreme road conditions such as sand and swamps, the vehicle can easily slip and cause the wheels to sink due to the high fluidity of soft soil particles in sand and swamps, seriously affecting the vehicle's passability; and since slipping and idling will produce invalid work, the vehicle's fuel or electricity consumption will be increased in vain.

[0003] At present, the improvement of vehicle's carrying capacity under extreme road conditions is mainly achieved by controlling the vehicle to increase torque, increase tire tread thickness, switch power output source and suspension travel, which greatly increases the manufacturing and driving operation costs of the vehicle; most of the theoretical models of wheel torque control in existing vehicle anti-skid technologies are based on the research of wheel-ground contact dynamics model under hard road conditions, ignoring the high fluidity of soil particles on soft roads.

[0004] Due to the large difference in the wheel-ground contact mechanical properties under soft and hard road conditions, the wheel-ground contact dynamics model under a single hard road condition cannot well express the mechanical properties under soft road conditions, especially under extreme working conditions, which is more likely to cause slippage and vehicle sinking. Summary of the invention

[0005] In view of the problems in the prior art, the present disclosure provides a method for controlling vehicle tire force under extreme road conditions, which can effectively improve the vehicle's ability to escape from trouble under extreme conditions.

[0006] The present disclosure provides a method for controlling vehicle tire force under extreme road conditions, comprising the following steps:

[0007] S1, through discrete element simulation software, build the mechanical model of tire and road surface, and simulate the longitudinal sliding force under different road and soil conditions. and slip rate the relationship between;

[0008] S2, determine the peak point of longitudinal slip force under various road conditions and its corresponding slip rate ;

[0009] S3, judging the road type, taking the longitudinal sliding force peak point ( , ) as the tracking point, by changing the current slip rate, the vehicle can obtain the maximum longitudinal slip force when it slips or is about to slip, thereby improving the vehicle's escape and passing capabilities.

[0010] Furthermore, the specific method of step S1 includes:

[0011] Select a variety of soils to conduct road soil material property tests to determine the parameters that affect tire-soil contact characteristics;

[0012] Rolling friction tests were conducted on actual tires and these soils to obtain the relationship between longitudinal slip force and slip rate as the actual calibration value;

[0013] A mechanical model of the tire and the road surface is constructed by discrete element simulation software, wherein the simulated tire parameters involved in the model adopt the above-mentioned actual tire parameter values, and the soil parameters involved adopt the actual soil of the above-mentioned soil material property test;

[0014] The constructed discrete element simulation model is simulated to obtain the relationship between the longitudinal slip force and the slip rate, and compared with the above-mentioned actual calibration values ​​for verification;

[0015] Enrich soil parameters, use discrete elements to perform large-scale simulations, and construct wheel-ground contact mechanical characteristic curves that represent the relationship between longitudinal sliding force and slip rate under various road surfaces;

[0016] Based on the above data, the sliding slip rates on various road surfaces are obtained by fitting. and longitudinal sliding force The relationship model between is shown in the following formula;

[0017]

[0018] in, , are the parameters to be fitted.

[0019] Furthermore, in step S1:

[0020] The parameters affecting tire-soil contact characteristics include: water content, friction modulus and cohesion;

[0021] The tire parameters include size and quality.

[0022] Furthermore, in step S1:

[0023] The various soil types selected included: sandy and swampy.

[0024] Furthermore, the step S3 specifically includes:

[0025] Determine the road surface type;

[0026] Slip rate when entering various road surfaces and longitudinal sliding force In the relationship model between the current road surface conditions, the peak point of the longitudinal slip force is selected ( , );

[0027] Taking the slip rate as the tracking target, the control goal of obtaining the maximum longitudinal slip force is achieved by calculating and changing the current slip rate, thereby keeping the vehicle in the maximum traction state at all times and improving the vehicle's escape and passing capabilities.

[0028] Furthermore, in step S3, the method for changing the current slip rate includes: controlling the size of the tire torque.

[0029] Compared with the prior art, the beneficial effects of the present invention are: (1) a soil-tire contact mechanical property model under a parameterized structural road surface is formed, and the relationship between the slip rate and the longitudinal slip force during wheel-ground contact is established; (2) a longitudinal slip force peak point theory is formed, which provides a theoretical mechanism for the subsequent control of the vehicle's driving ability under extreme road conditions; (3) the vehicle's driving ability under extreme road conditions can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0031] Figure 1 A flow chart of an exemplary parameterized wheel-ground contact dynamics modeling method according to the present disclosure;

[0032] Figure 2 An example of the relationship between the slip rate and the longitudinal slip force on different road types;

[0033] Figure 3 This is a flow chart of the vehicle tire force control method under extreme road conditions. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] The present disclosure provides a method for controlling vehicle tire force under extreme road conditions. The flowchart of an exemplary embodiment is shown in the attached figure. Figure 3 As shown, the following steps are included:

[0036] (1) Tire parameterized wheel-ground contact dynamics modeling, including:

[0037] By conducting a road soil material property test on certain specific actual soils, the parameters affecting the tire-soil contact characteristics are determined, including: water content, friction modulus, and cohesion, etc.; by conducting a rolling friction test on the actual tire and the certain specific soils, the relationship between the longitudinal sliding force and the slip rate is obtained as the actual calibration value;

[0038] A tire-road contact model is constructed by discrete element simulation software, wherein the simulated tire parameters involved in the model adopt the above-mentioned actual tire parameter values, including size, mass, etc.; the soil parameters involved in the model adopt the above-mentioned actual soil for the soil material property test; a simulation experiment is conducted on the discrete element simulation model to obtain the relationship between the longitudinal slip force and the slip rate, and the relationship is compared and verified with the above-mentioned actual calibration value as a set of data in the parametric modeling;

[0039] By enriching the soil parameters, using discrete elements for large-scale simulation, and constructing wheel-ground contact mechanical characteristic curves under various road surfaces for parametric modeling, as shown in the attached figure. Figure 1 As shown;

[0040] Based on the above data, a dynamic model reflecting the mechanical characteristics of tire-ground contact is fitted to form a parameterized wheel-ground contact dynamic model based on various road surfaces. The model reflects the slip rate and longitudinal sliding force The relationship between them is shown in the following formula:

[0041]

[0042] in, , are the parameters to be fitted.

[0043] (2) Study the characteristics of the wheel-ground contact dynamics model, which is composed of the tire longitudinal slip force The slip rate reflects:

[0044] Tire longitudinal slip force As the slip rate increases, it shows a nonlinear increasing trend. When the slip rate reaches a certain value, the tire longitudinal slip force reaches its maximum value and then remains unchanged or decreases.

[0045] The maximum value that the longitudinal sliding force can reach is called the longitudinal sliding force peak point The initial slip rate corresponding to this point is Combined with the parameterized wheel-earth dynamics model, different road types have different longitudinal slip force peak points ( , ) combination, as shown in the attached Figure 2 shown.

[0046] (3) The peak point of the longitudinal slip force obtained based on the parameterized wheel-ground contact dynamics model ( , ) as a tracking point, so that the vehicle can obtain the maximum longitudinal sliding force when it slips or is about to slip, improving the vehicle's ability to escape and pass:

[0047] By judging the road type, the peak point of longitudinal slip force under the current road condition is selected in the parameterized wheel-ground contact dynamics model ( , ), and takes the slip rate as the tracking target. By controlling the tire torque and thus changing the current slip rate, a method with slip rate as the control target is implemented, thereby keeping the vehicle in the maximum traction state at all times and improving the vehicle's escape and passing capabilities.

[0048] The above technical scheme is only an exemplary embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A method for controlling the driving force of a vehicle tire under extreme road conditions, comprising the following steps: S1, through discrete element simulation software, build the mechanical model of tire and road surface, and simulate the longitudinal sliding force under different road and soil conditions. and slip rate the relationship between; S2, determine the peak point of longitudinal slip force under various road conditions and its corresponding slip rate ; S3, judging the road type, taking the longitudinal sliding force peak point ( , ) as the tracking point, by changing the current slip rate, the vehicle can obtain the maximum longitudinal sliding force when skidding, thereby improving the vehicle's ability to escape and pass; The specific method of step S1 includes: Select a variety of soils to conduct road soil material property tests to determine the parameters that affect tire-soil contact characteristics; Rolling friction tests were conducted on actual tires and these soils to obtain the relationship between longitudinal slip force and slip rate as the actual calibration value; A mechanical model of the tire and the road surface is constructed by discrete element simulation software, wherein the simulated tire parameters involved in the model adopt the above-mentioned actual tire parameter values, and the soil parameters involved adopt the actual soil of the above-mentioned soil material property test; The constructed discrete element simulation model is simulated to obtain the relationship between the longitudinal slip force and the slip rate, and compared with the above-mentioned actual calibration values ​​for verification; Enrich soil parameters, use discrete elements to perform large-scale simulations, and construct wheel-ground contact mechanical characteristic curves that represent the relationship between longitudinal sliding force and slip rate under various road surfaces; Based on the above simulation data, the sliding slip rates on various road surfaces are obtained by fitting. and longitudinal sliding force The relationship model is as follows: in, , is the parameter to be fitted; Step S3 specifically includes: Determine the road surface type; Slip rate when entering various road surfaces and longitudinal sliding force In the relationship model between the current road surface conditions, the peak point of the longitudinal slip force is selected ( , ); Taking the slip rate as the tracking target, the control goal of obtaining the maximum longitudinal slip force is achieved by calculating and changing the current slip rate, thereby keeping the vehicle in the maximum traction state at all times and improving the vehicle's escape and passing capabilities.

2. The method according to claim 1, characterized in that In step S1: The parameters affecting tire-soil contact characteristics include: water content, friction modulus and cohesion; The tire parameters include size and quality.

3. The method according to claim 1 or 2, characterized in that: In step S1: The soil types selected include: sandy and swampy.

4. The method according to claim 1, characterized in that: In step S3, the method for changing the current slip rate includes: controlling the size of the tire torque.

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