Method and System for Allocating Maximum Additional Yaw Torque of a Multi-Axle In-Wheel Motor Vehicle

Abstract

The present invention relates to the technical field of electric vehicles, and particularly to a method and system for distributing the maximum additional yaw torque of a multi-axis in-wheel motor vehicle. The distribution method includes the following steps: determining the maximum torque values that can be used to enhance the clockwise and counterclockwise rotation tendencies based on the remaining available total torque of the left and right in-wheel motors and the remaining available braking torque of the left and right brake calipers; determining the maximum additional yaw torque that can be provided by the left and right wheels based on the maximum torque values that can be used to enhance the clockwise and counterclockwise rotation tendencies; determining the maximum additional yaw total torque available for the vehicle based on the maximum additional yaw torque that can be provided by the left and right sides; and distributing the execution torques of each in-wheel motor and brake caliper based on the distribution coefficient determined by the vehicle's required additional yaw torque and the maximum additional yaw total torque. It can solve the problem in the prior art that forcibly controlling the execution of the excess yaw torque may cause risks of damaging the in-wheel motors and braking systems.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and in particular to a method and system for distributing the maximum additional yaw torque of a multi-axis in-wheel motor vehicle. Background Art

[0002] An in-wheel motor is a motor designed by integrating the "power system, transmission system, and braking system" of a vehicle. In-wheel motor technology is also known as in-wheel motor technology. Its greatest feature is that it integrates the power device, transmission device, and braking device into the wheel hub, greatly simplifying the mechanical part of the electric vehicle.

[0003] With the strict environmental protection standards and regulations, the development trend of electric vehicles is rapid. Among them, in-wheel motor vehicles can improve the handling stability and safety of the vehicle because the torque of each wheel can be independently controlled. However, due to the differences in the states and output capabilities of each in-wheel motor and braking system, there is an upper limit to the maximum additional yaw torque required for handling stability control.

[0004] If this upper limit is exceeded, the vehicle cannot increase the additional yaw torque beyond this part. If the yaw torque beyond this part is forcibly controlled, it may cause the dynamic performance of the whole vehicle to change or cause the in-wheel motor and braking system to work beyond their capabilities, posing a risk of damaging the in-wheel motor and braking system. Summary of the Invention

[0005] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a method and system for distributing the maximum additional yaw torque of a multi-axis in-wheel motor vehicle, which can solve the problem that forcibly controlling the yaw torque beyond the limit in the prior art may cause the dynamic performance of the whole vehicle to change or cause the in-wheel motor and braking system to work beyond their capabilities, posing a risk of damaging the in-wheel motor and braking system.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a method for distributing the maximum additional yaw torque of a multi-axis in-wheel motor vehicle, characterized by including the following steps:

[0008] Determine the maximum available torque for enhancing the clockwise and counterclockwise rotation trends according to the remaining available total torque of the left and right in-wheel motors and the remaining available braking torque of the left and right brake calipers;

[0009] Based on the maximum available torque for enhancing the clockwise and counterclockwise rotation trends, determine the maximum additional yaw torque that the left and right wheels can provide;

[0010] Determine the maximum additional yaw total torque that the vehicle can provide according to the maximum additional yaw torque that the left and right sides can provide;

[0011] Based on the distribution coefficient determined by the additional yaw torque and the maximum total additional yaw torque according to the vehicle requirements, the execution torques of each wheel hub motor and brake caliper are distributed.

[0012] In some alternative solutions, determining the maximum torque values that can be used to enhance the clockwise and counterclockwise rotation tendencies according to the remaining available total torque of the left and right wheel hub motors and the remaining available braking torques of the left and right brake calipers includes:

[0013] Determine the maximum total torques that the left and right wheels can provide to make the vehicle rotate clockwise and counterclockwise around the geometric center according to the remaining available total increment and remaining available decrement torques of the left and right wheel hub motors and the remaining available braking torques of the left and right brake calipers;

[0014] Determine the maximum torque values that can be used to enhance the clockwise and counterclockwise rotation tendencies according to the maximum total torques that the left and right wheels can provide to make the vehicle rotate clockwise and counterclockwise around the geometric center.

[0015] In some alternative solutions,

[0016] According to the formula Determine the maximum total torque ΔT lmax1 that the left wheel can provide to make the vehicle rotate clockwise around the geometric center and the maximum total torque ΔT lmax2 for counterclockwise rotation;

[0017] According to the formula Determine the maximum total torque ΔT rmax1 that the right wheel can provide to make the vehicle rotate counterclockwise around the geometric center and the maximum total torque ΔT rmax2 for clockwise rotation;

[0018] According to ΔT min1 = min(ΔT lmax1 , ΔT rmax2 ), determine the maximum torque value ΔT min1 that can be used to enhance the clockwise rotation tendency;

[0019] According to ΔT min2 = min(ΔT lmax2 , ΔT rmax1 ), determine the maximum torque value ΔT min2 that can be used to enhance the counterclockwise rotation tendency;

[0020] wherein, ΔT lmmax1 is the remaining available total increment torque of the left wheel hub motor, ΔT lmmax2 is the remaining available total decrement torque of the left wheel hub motor, ΔT lkmax is the remaining available braking torque of the left brake caliper, ΔT rmmax1is the total remaining available incremental torque of the right hub motor, ΔT rmmax2 is the total remaining available decremental torque of the right hub motor, ΔT rkmax is the remaining available braking torque of the right brake caliper.

[0021] In some alternative solutions, the maximum additional yaw torque that can be provided by the left and right wheels determined based on the enhanced clockwise and counterclockwise rotation trends using the maximum available torque includes:

[0022] Determine the torque increase and decrease of the left and right hub motors on each axis and the torque increase and decrease of the brake calipers according to the maximum available torque of the enhanced clockwise and counterclockwise rotation trends;

[0023] Determine the maximum additional yaw torque that can be provided by the left and right wheels according to the maximum torque increase of the left and right hub motors on each axis and the maximum torque increase of the brake calipers.

[0024] In some alternative solutions, according to the formula Determine the maximum

[0025] additional yaw ΔM l that can be provided by the left side and the maximum additional yaw torque ΔM r that can be provided by the right side;

[0026] where, ΔT lmi is the torque increase and decrease of the left hub motor of the i-th axis; ΔT lki is the torque increase and decrease of the left brake caliper of the i-th axis; d i is the distance from the vehicle geometric center to the left or right wheel of the i-th axis; ΔT rmi is the torque increase and decrease of the right hub motor of the i-th axis; ΔT rki is the torque increase and decrease of the right brake caliper of the i-th axis; decrease; θ li is the angle between the vector connecting the vehicle geometric center to the center of the left wheel of the i-th axis and the resultant vector of ΔT lmi +ΔT lki , θ li ∈[0,2π]; θ ri is the angle between the vector connecting the vehicle geometric center to the center of the right wheel of the i-th axis and the resultant vector of ΔT rmi +ΔT rki resultant vector, θ ri ∈[0,2π], n is the number of axes, and S is the rotation direction.

[0027] In some alternative solutions, when the vehicle rotates clockwise with enhanced rotation (S = 1), make ΔT lmi , ΔT lki , ΔT rmi and ΔT rki satisfy:

[0028]

[0029] When the vehicle rotates counterclockwise and intensifies (S = -1), make

[0030] ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rki satisfy:

[0031]

[0032] Based on the above constraint relationships, make ΔM l ,ΔM r When the absolute value is the largest, determine the corresponding ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rki ;

[0033] Among them, S represents the rotation direction, ΔT lmi is the torque increment and decrement of the left hub motor of the i-th axis, ΔT lki is the torque increment and decrement of the left brake caliper of the i-th axis, ΔT rmi is the torque increment and decrement of the right hub motor of the i-th axis; ΔT rki is the torque increment and decrement of the right brake caliper of the i-th axis; T lmmaxi is the maximum output torque of the left hub motor of the i-th axis, T rmmaxi is the maximum output torque of the right hub motor of the i-th axis, T lmi is the driver intention torque of the left hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rmi is the driver intention torque of the right hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rkmaxi is the maximum output torque of the right brake caliper of the i-th axis, T lkmaxi is the maximum output torque of the left brake caliper of the i-th axis, T lki is the driver intention torque of the left brake caliper of the i-th axis calculated based on the brake pedal, T rki is the driver intention torque of the right brake caliper of the i-th axis calculated based on the brake pedal, and n is the number of axes.

[0034] In some alternative solutions, according to ΔM max = ΔM l + ΔM r to determine the maximum additional yaw total torque ΔM max available for the vehicle.

[0035] In some alternative solutions, according to Determine the distribution coefficient γ, where ΔM is the additional yaw torque required for the vehicle.

[0036] In some alternative solutions, according to the formula Determine the execution torques of the hub motors and brake calipers of each wheel for distribution;

[0037] where, ΔT l ′ mi is the torque increment executed by the left hub motor of the i-th axle; ΔT r ′ mi is the torque increment executed by the right hub motor of the i-th axle; ΔT l ′ ki is the torque increment executed by the left brake caliper of the i-th axle; ΔT r ′ ki is the torque increment executed by the right brake caliper of the i-th axle.

[0038] On the other hand, the present invention provides a maximum additional yaw torque distribution system for a multi-axle hub motor vehicle, including:

[0039] A torque maximum determination unit, which is used to determine the maximum torque that can be used to enhance the clockwise and counterclockwise rotation trends according to the remaining available total torque of the left and right hub motors and the remaining available braking torques of the left and right brake calipers;

[0040] A wheel-provided yaw torque determination unit, which is used to determine the maximum additional yaw torques that can be provided by the left and right wheels based on the maximum torque that can be used to enhance the clockwise and counterclockwise rotation trends;

[0041] A vehicle-provided total yaw torque determination unit, which is used to determine the maximum additional total yaw torque that can be provided by the vehicle according to the maximum additional yaw torques that can be provided by the left and right sides;

[0042] An execution torque determination unit, which is used to distribute the execution torques of each wheel's execution components based on the distribution coefficient determined by the vehicle demand additional yaw torque and the maximum additional total yaw torque.

[0043] Compared with the prior art, the advantages of the present invention are as follows: First, according to the remaining available total torque of the left and right hub motors and the remaining available braking torques of the left and right brake calipers, the maximum torque that can be used to enhance the clockwise and counterclockwise rotation trends is determined; then, based on the maximum torque that can be used to enhance the clockwise and counterclockwise rotation trends, the maximum additional yaw torques that can be provided by the left and right wheels are determined; then, according to the maximum additional yaw torques that can be provided by the left and right sides, the maximum additional total yaw torque that can be provided by the vehicle is determined; based on the distribution coefficient determined by the vehicle demand additional yaw torque and the maximum additional total yaw torque, the execution torques of each wheel hub motor and brake caliper are distributed. By accurately calculating the maximum additional yaw torque that can be provided by the vehicle, it is ensured that the hub motor and the braking system do not work beyond their capacity ranges, avoiding problems that may cause risks of damaging the hub motor and the braking system, and improving the handling stability and safety of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is a schematic flowchart of the method for distributing the maximum additional yaw torque of a multi-axis hub motor vehicle in an embodiment of the present invention;

[0046] Figure 2 It is a schematic diagram of the principle of the maximum additional total yaw torque that can be provided by the vehicle in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0048] The following will further elaborate on the embodiments of the present invention with reference to the drawings.

[0049] As Figure 1 shown, the present invention provides a method for distributing the maximum additional yaw torque of a multi-axis hub motor vehicle, including the following steps:

[0050] S1: Determine the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation trends based on the remaining available total torque of the left and right hub motors and the remaining available braking torque of the left and right brake calipers.

[0051] Step S1 includes:

[0052] S11: Determine the maximum total torque that the left and right wheels can provide to make the vehicle rotate clockwise and counterclockwise around the geometric center respectively based on the remaining available total incremental and decremental torques of the left and right hub motors and the remaining available braking torques of the left and right brake calipers.

[0053] Calculating the remaining available total incremental and decremental torques of the left and right hub motors and the remaining available braking torques of the left and right brake calipers includes the following steps:

[0054] A: Calculate the maximum output torque of each hub motor based on its current torque, temperature, and fault status.

[0055] Specifically, the differences in the operating conditions of each hub motor result in differences in its speed, temperature, and faults. For example, when the vehicle is turning, the speed of the inner wheels is less than that of the outer wheels. Also, for example, some hub motors have a first-level fault and need to limit power usage, while some motors have a second-level fault and are prohibited from being used. Therefore, each hub motor calculates its maximum output torque according to its current torque, temperature, and fault status. The calculation formula is:

[0056]

[0057] Where: T lmmaxi is the maximum output torque of the left hub motor of the i-th axis; T rmmaxi is the maximum output torque of the right hub motor of the i-th axis; W fi is the actual speed of the left hub motor of the i-th axis; W ri is the actual speed of the right hub motor of the i-th axis; a fi is the fault level coefficient of the left hub motor of the i-th axis; a ri is the fault level coefficient of the right hub motor of the i-th axis; k fi is the fault temperature adjustment coefficient of the left hub motor of the i-th axis; k ri is the fault temperature adjustment coefficient of the right hub motor of the i-th axis. T(W li ) is the external characteristic torque of the left hub motor of the i-th axis at W fi ; T(W ri ) is the external characteristic torque of the right hub motor of the i-th axis at W ri ;

[0058] Where: a fi , a riThe value can be 1, 0.5, and 0. When there is no fault, the value is 1; when there is a general fault, the value is 0.5; when there is a serious fault, the value is 0.

[0059] Where: i is the vehicle axle number, i ∈ [1, n]. The axle number closest to the vehicle head is 1, and the axle number closest to the vehicle tail is n.

[0060] B: Determine the total remaining available incremental and decremental torques of the left and right hub motors according to the maximum output torque of each hub motor and the torque required by the driving intention.

[0061] Specifically, the total remaining available incremental and decremental torques of the left and right hub motors are equal to the sum of the maximum output torques of each hub motor on the left and right sides minus or plus the total torque of the driver's intention.

[0062] For the left hub motor, the total torque available for incremental torque of the left hub motor and the total torque available for decremental torque of the left hub motor:

[0063]

[0064] Where: T lmi is the driver's intention torque calculated by the left hub motor of the i-th axle based on the accelerator pedal and the brake pedal; ΔT lmmax1 is the total remaining available incremental torque of the left hub motor;

[0065] ΔT lmmax2 is the total remaining available decremental torque of the left hub motor.

[0066] T lmi > 0 indicates that the driver steps on the accelerator and does not step on the brake pedal, and the left hub motor of the i-th axle outputs a torque of magnitude T lmi to drive the vehicle forward; T lmi = 0 indicates that the driver does not step on the accelerator and does not step on the brake pedal, and the vehicle does not drive or brake; T lmi < 0 indicates that the driver does not step on the accelerator but steps on the brake pedal, and the left hub motor of the i-th axle outputs a torque of magnitude T lmi in absolute value to brake the vehicle forward;

[0067] ΔT lmmax1 represents the maximum value that the left hub motor can increase based on its maximum output torque on the basis of the driver's intention torque T lmi ; ΔT lmmax2 represents the maximum value that the left hub motor can decrease based on its maximum output torque on the basis of the driver's intention torque T lmi ;

[0068] For the right hub motor, the sum of the remaining available torques for increasing the torque of the right hub motor and the sum of the remaining available torques for decreasing the torque of the right hub motor:

[0069]

[0070] Where: T rmi is the driver intention torque calculated by the right hub motor of the i-th axis based on the accelerator pedal and the brake pedal; ΔT rmmax1 is the total remaining available incremental torque of the right hub motor;

[0071] ΔT rmmax2 is the total remaining available decremental torque of the right hub motor.

[0072] T rmi > 0 indicates that the driver presses the accelerator and does not press the brake pedal, and the right hub motor of the i-th axis outputs a torque of magnitude T rmi to drive the vehicle forward; T rmi = 0 indicates that the driver does not press the accelerator and does not press the brake pedal, and the vehicle is neither driven nor braked; T rmi < 0 indicates that the driver does not press the accelerator but presses the brake pedal, and the right hub motor of the i-th axis outputs an absolute value torque of magnitude T rmi to brake the vehicle forward;

[0073] ΔT rmmax1 represents the maximum value that the right hub motor can increase based on its maximum output torque on the basis of the driver intention torque T rmi ; ΔT rmmax2 represents the maximum value that the i-th axis hub motor can decrease based on its maximum output torque on the basis of the driver intention torque T rmi .

[0074] C: Determine the remaining available braking torques of the left and right brake calipers according to the total remaining available braking torque of the brake caliper and the driving intention braking torque.

[0075] The total remaining available braking torque of the left brake caliper is:

[0076]

[0077] The total remaining available braking torque of the right brake caliper:

[0078]

[0079] Where: ΔT lkmax is the total remaining available braking torque of the left brake caliper; ΔT rkmax is the total remaining available braking torque of the right brake caliper; T lkmaxiis the maximum braking torque output by the left brake caliper on the i-th axis; T rkmaxi is the maximum braking torque output by the right brake caliper on the i-th axis;

[0080] T lki is the driver's intended braking torque calculated by the left brake caliper on the i-th axis based on the brake pedal opening; T rki is the driver's intended braking torque calculated by the right brake caliper on the i-th axis based on the brake pedal opening.

[0081] T lkmaxi 、T lkmaxi are determined by the mechanical characteristics of the braking system and are fixed values.

[0082] Calculate the maximum total torque that the left and right wheels can provide to make the vehicle rotate clockwise and counterclockwise around the geometric center, including:

[0083] If the remaining available total braking torque of the left brake caliper and the remaining available total reduction torque of the left hub motor are applied to the left side of the vehicle, the resultant torque of the two will reduce the rotational speed of the left wheel and at the same time make the vehicle rotate counterclockwise around the geometric center. Therefore, for the left wheel, the maximum torque available to make the vehicle rotate counterclockwise around the geometric center is the sum of the remaining available total braking torque of the left brake caliper and the remaining available total reduction torque of the left hub motor; if the remaining available total increase torque of the left hub motor is applied to the left side of the vehicle, the rotational speed of the left wheel will increase and at the same time make the vehicle rotate clockwise around the geometric center. Therefore, for the left wheel, the maximum torque available to make the vehicle rotate clockwise around the geometric center is the remaining available total increase torque of the left hub motor. The calculation method is as follows:

[0084]

[0085] where: ΔT lmax1 is the maximum total torque that the left wheel can provide to make the vehicle rotate clockwise around the geometric center; ΔT lmax2 is the maximum total torque that the left wheel can provide to make the vehicle rotate counterclockwise around the geometric center, ΔT lmmax1 is the remaining available total increase torque of the left hub motor, ΔT lmmax2 is the remaining available total reduction torque of the left hub motor, ΔT lkmax is the remaining available braking torque of the left brake caliper.

[0086] If the total remaining available braking torque of the right - hand brake caliper and the total remaining available reduction torque of the right - hand hub motor are applied to the right side of the vehicle, the resultant torque of the two makes the rotational speed of the right - hand wheel smaller and causes the vehicle to rotate clockwise around the geometric center. Therefore, for the right - hand wheel, the maximum torque available for making the vehicle rotate clockwise around the geometric center is the sum of the total remaining available braking torque of the right - hand brake caliper and the total remaining available reduction torque of the right - hand hub motor; if the total remaining available increase torque of the right - hand hub motor is applied to the right side of the vehicle, it makes the rotational speed of the right - hand wheel increase and causes the vehicle to rotate counter - clockwise around the geometric center. Therefore, for the right - hand wheel, the maximum torque available for making the vehicle rotate counter - clockwise around the geometric center is the total remaining available increase torque of the right - hand hub motor. The calculation method is as follows:

[0087]

[0088] Where: ΔT rmax1 is the maximum total torque that the right - hand wheel can provide to make the vehicle rotate counter - clockwise around the geometric center; ΔT rmax2 is the maximum total torque that the right - hand wheel can provide to make the vehicle rotate clockwise around the geometric center, ΔT rmmax1 is the total remaining available increase torque of the right - hand hub motor, ΔT rmmax2 is the total remaining available reduction torque of the right - hand hub motor, ΔT rkmax is the remaining available braking torque of the right - hand brake caliper.

[0089] S12: Determine the maximum torque values that can be used to enhance the clockwise and counter - clockwise rotation trends based on the maximum total torques that the left - and right - hand wheels can provide to make the vehicle rotate clockwise and counter - clockwise around the geometric center respectively.

[0090] If it is to enhance the clockwise rotation trend, the left - hand wheel can provide the maximum total torque for the vehicle to rotate clockwise around the geometric center, and the right - hand wheel can provide the maximum total torque for the vehicle to rotate clockwise around the geometric center. To keep the power performance of the whole vehicle unchanged, the increased torque on one side should be equal to the decreased torque on the other side. The maximum values of the increased and decreased torques should be the minimum of the maximum total torque that the left - hand wheel can provide for the vehicle to rotate clockwise around the geometric center and the maximum total torque that the right - hand wheel can provide for the vehicle to rotate clockwise around the geometric center, that is: ΔT min1 = min(ΔT lmax1 , ΔT rmax2 ), and at the same time let s = 1.

[0091] Further, if it is to enhance the counterclockwise rotation trend, the left wheel can provide the maximum total torque for the vehicle to rotate counterclockwise around the geometric center, and the right wheel can provide the maximum total rotation for the vehicle to rotate counterclockwise around the geometric center. To keep the power performance of the whole vehicle unchanged, the increased torque on one side should be equal to the decreased torque on the other side, and the maximum value of the increased and decreased torque should be the minimum of the maximum total torque that the left wheel can provide for the vehicle to rotate counterclockwise around the geometric center and the maximum total rotation that the right wheel can provide for the vehicle to rotate counterclockwise around the geometric center, that is: ΔT min2 = min(ΔT lmax2 , ΔT rmax1 ), and at the same time let s = -1.

[0092] Where: ΔT min1 is the maximum available torque of the left and right wheels to strengthen the clockwise rotation of the vehicle around the geometric center; ΔT min2 is the maximum available torque of the left and right wheels to strengthen the counterclockwise rotation of the vehicle around the geometric center;

[0093] S2: Based on the maximum available torque to strengthen the clockwise and counterclockwise rotation trends, determine the maximum additional yaw torque that the left and right wheels can provide.

[0094] Step S2 specifically includes:

[0095] S21: According to the maximum available torque to strengthen the clockwise and counterclockwise rotation trends, determine the torque increase and decrease of the left and right hub motors on each axis and the torque increase and decrease of the brake calipers.

[0096] S22: According to the maximum torque increase of the left and right hub motors on each axis and the maximum torque increase of the brake calipers, determine the maximum additional yaw torque that the left and right wheels can provide.

[0097] As Figure 2 shown, specifically, according to the formula determine the maximum additional yaw ΔM l that the left side can provide and the maximum additional yaw torque ΔM r that the right side can provide;

[0098] Where, ΔT lmi is the torque increase and decrease of the left hub motor on the i-th axis; ΔT lki is the torque increase and decrease of the left brake caliper on the i-th axis; d i is the distance from the vehicle geometric center to the left or right wheel on the i-th axis; ΔT rmi is the torque increase and decrease of the right hub motor on the i-th axis; ΔT rki is the torque increase and decrease of the right brake caliper on the i-th axis; θ li is the vector connecting the vehicle geometric center to the center of the left wheel on the i-th axis and ΔTlmi +ΔT lki The included angle, θ, between the resultant vectors of li ∈[0, 2π]; θ ri is the included angle between the vector connecting the geometric center of the vehicle to the center of the right wheel of the i-th axle and ΔT rmi +ΔT rki resultant vectors, θ ri ∈[0, 2π], n is the number of axles; S is the rotation direction.

[0099] ΔM l < 0, ΔM r < 0 is the maximum additional yaw torque that the vehicle can provide counterclockwise around the geometric center; ΔM l > 0, ΔM r > 0 is the maximum additional yaw torque that the vehicle can provide clockwise around the geometric center; ΔM l = 0, ΔM r = 0 means that no additional yaw torque for the vehicle to rotate around the geometric center can be provided.

[0100] By considering the influence of the geometric dimensions of a multi-axle vehicle and multiple steering axles on the maximum additional yaw torque of the vehicle, the accuracy of calculating the maximum additional yaw torque that the vehicle can provide can be improved.

[0101] When solving ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rki ,

[0102] ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rki The existing constraints include two aspects. One aspect is that their magnitudes cannot exceed the output capacity range of the in-wheel motors. The other aspect is that the total increase and decrease of the left-side torque are equal to the total increase of the right-side torque, and both are equal to the maximum available torque of the left and right wheels. The constraint conditions are:

[0103]

[0104] Furthermore, the above can be interpreted as two cases according to the clockwise and counterclockwise rotations of the vehicle:

[0105] ① In the case of the vehicle rotating clockwise and intensifying (S = 1), the left brake calipers cannot increase the braking torque additionally, the left in-wheel motors should output driving torque, the right brake calipers can increase the braking torque additionally, and the right in-wheel motors can output braking torque. The constraint conditions are:

[0106]

[0107] ② When the vehicle rotates counterclockwise with increasing speed (S = -1), the left brake calipers can output an additional braking torque, and the left hub motors can output a braking torque. The right brake calipers cannot output an additional braking torque, and the right hub motors can output a driving torque. The constraint conditions are:

[0108]

[0109] Based on the above constraint relationships, when the absolute values of ΔM l and ΔM r are maximized respectively, calculate the corresponding ΔT lmi , ΔT lki , ΔT rmi and ΔT rki .

[0110] Among them, S represents the rotation direction, ΔT lmi is the torque increase or decrease of the left hub motor of the i-th axis, ΔT lki is the torque increase or decrease of the left brake caliper of the i-th axis, ΔT rmi is the torque increase or decrease of the right hub motor of the i-th axis; ΔT rki is the torque increase or decrease of the right brake caliper of the i-th axis; T lmmaxi is the maximum output torque of the left hub motor of the i-th axis, T rmmaxi is the maximum output torque of the right hub motor of the i-th axis, T lmi is the driver intention torque of the left hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rmi is the driver intention torque of the right hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rkmaxi is the maximum output torque of the right brake caliper of the i-th axis, T lkmaxi is the maximum output torque of the left brake caliper of the i-th axis, T lki is the driver intention torque of the left brake caliper of the i-th axis calculated based on the brake pedal, T rki is the driver intention torque of the right brake caliper of the i-th axis calculated based on the brake pedal, and n is the number of axes.

[0111] The following gives a method for solving ΔT lmi , ΔT lki , ΔT rmi and ΔT rki :

[0112] Let:

[0113]

[0114] Among them: ΔT max is the maximum torque increase or decrease of the left and right sides of the vehicle; ΔT lmmaxiis the maximum torque increase of the left hub motor of the i-th axis; ΔT lkmaxi is the maximum torque increase of the left brake caliper of the i-th axis; ΔT rmmaxi is the maximum torque increase of the right hub motor of the i-th axis;

[0115] ΔT lkmaxi is the maximum torque increase of the right brake caliper of the i-th axis;

[0116] From the total torque Under certain circumstances, its sub-torque ΔT lmi 、ΔT lki 、ΔT rmi 、ΔT rki make ΔM l ,ΔM r maximum, then the sub-torque ΔT lmi 、ΔT lki 、ΔT rmi 、ΔT rki should preferably use the state with a larger effective length.

[0117] For the left wheel, the maximum torque increase ΔT of the hub motor of each wheel lmmaxi 、the maximum torque increase ΔT of the brake caliper lkmaxi and its constitute a parameter group The serial number of the wheel parameter group of the left wheel of the i-th axis is j, which means that the left wheel is sorted in descending order according to its among all the left wheels and its serial number is j. That is, (i, j) is the left wheel of the i-th axis whose sorting serial number from large to small is j, and j ∈ [1, n]. Conversely, then ΔT lmmaxj represents the maximum torque increase of the hub motor with the sorting serial number j of the left wheel, that is, ΔT lmmaxj =ΔT lmmaxi .

[0118] For the right wheel, the maximum torque increase ΔT of the hub motor of each wheel rmmaxi 、the maximum torque increase ΔT of the brake caliper rkmaxi and its constitute a parameter group The serial number of the wheel parameter group of the right wheel of the i-th axis is k, which means that the left wheel is sorted in descending order according to its among all the left wheels and its serial number is k. That is, (i, k) is the right wheel of the i-th axis whose sorting serial number from large to small is k and k ∈ [1, n]. Conversely, then ΔT rmmaxkDenoted as the maximum increase in hub motor torque of the right wheel with its sorting sequence number k, i.e., ΔT rmmaxk = ΔT rmmaxi .

[0119] ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rki are calculated as:

[0120]

[0121] Where: ΔT(j) lmaxadd is the sum of the maximum increase in hub motor torque ΔT of the left wheel with its sorting sequence number not greater than j lmmaxj and the maximum increase in brake caliper torque ΔT of the left wheel with its sorting sequence number not greater than j lkmmaxj ; ΔT(j - 1) lmaxadd is the sum of the maximum increase in hub motor torque ΔT of the left wheel with its sorting sequence number not greater than j - 1 lmmaxj and the maximum increase in brake caliper torque ΔT of the left wheel with its sorting sequence number not greater than j - 1 lkmmaxj ;

[0122] Where:

[0123] If j = 0, then let ΔT(0) lmaxadd = 0;

[0124] Where: ΔT(k) rmaxadd is the sum of the maximum increase in hub motor torque ΔT of the right wheel with its sorting sequence number not greater than k rmmaxk and the maximum increase in brake caliper torque ΔT of the right wheel with its sorting sequence number not greater than k rkmmaxk ; ΔT(k - 1) lmaxadd is the sum of the maximum increase in hub motor torque ΔT of the right wheel with its sorting sequence number not greater than k - 1 rmmaxk and the maximum increase in brake caliper torque ΔT of the right wheel with its sorting sequence number not greater than k - 1 rkmmaxk ;

[0125] Where:

[0126] If k = 0, then let ΔT(0) rmaxadd = 0;

[0127] ΔT lmi 、ΔT lki 、ΔT rmi and ΔT rkiIt is also the limit torque distributed to each wheel, which will never exceed the capabilities of the in-wheel motor and the braking system, avoiding the in-wheel motor and the braking system from operating beyond their capabilities and providing effective protection for them.

[0128] The ΔT calculated according to this lmi 、ΔT lki 、ΔT rmi and ΔT rki are used to further calculate the maximum ΔM l ,ΔM r .

[0129] ΔM f and ΔM r have three relative magnitude relationships, including: ΔM f =ΔM r 、

[0130] ΔM f >ΔM r and ΔM f <ΔM r .

[0131] S3: Determine the maximum additional yaw torque available for the vehicle based on the maximum additional yaw torques available on the left and right sides.

[0132] Based on ΔM max =ΔM l +ΔM r , determine the maximum additional yaw torque ΔM max available for the vehicle.

[0133] ΔM max represents the maximum ability of the entire vehicle to provide the maximum additional yaw torque for correcting and returning to normal steering when the vehicle is understeering or oversteering.

[0134] S4: Based on the distribution coefficient determined by the vehicle's required additional yaw torque and the maximum additional yaw torque, distribute the execution torques of the in-wheel motors and brake calipers of each wheel.

[0135] According to , determine the distribution coefficient γ, where ΔM is the vehicle's required additional yaw torque. The distribution coefficient γ is the ratio between the vehicle's required additional yaw torque and the vehicle's maximum torque, and γ ∈ [0,1].

[0136] Based on the ratio between the vehicle's required additional yaw torque and the vehicle's maximum torque and the maximum torque increment of each wheel, perform a secondary redistribution of the change amount of each target torque.

[0137] According to the formula , determine the execution torques distributed to the in-wheel motors and brake calipers of each wheel;

[0138] Among them, ΔT l ′ mi is the torque increment executed by the left hub motor of the i-th axis; ΔT r ′ mi is the torque increment executed by the right hub motor of the i-th axis; ΔT l ′ ki is the torque increment executed by the left brake caliper of the i-th axis; ΔT r ′ ki is the torque increment executed by the right brake caliper of the i-th axis.

[0139] The following gives a specific calculation method:

[0140]

[0141] Furthermore, if ΔM = 0 or ΔM max = 0, then γ = 0, and it can be known that:

[0142]

[0143] It can be known that:

[0144] Furthermore, if ΔM ≥ ΔM max then γ = 1

[0145]

[0146] It can be known that:

[0147] If ΔM < ΔM max then

[0148]

[0149] It can be known that:

[0150] On the other hand, the present invention provides a maximum additional yaw torque distribution system for a multi-axis hub motor vehicle. This system is used to execute the maximum additional yaw torque distribution method for a multi-axis hub motor vehicle, and includes:

[0151] A torque maximum value determination unit, which is used to determine the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation trends according to the remaining available total torque of the left and right hub motors and the remaining available braking torque of the left and right brake calipers;

[0152] The wheel provides a yaw torque determination unit, which is used to determine the maximum additional yaw torque that the left and right wheels can provide based on the maximum torque that can be used to enhance the clockwise and counterclockwise rotation tendencies;

[0153] The vehicle provides a total yaw torque determination unit, which is used to determine the maximum additional total yaw torque that the vehicle can provide based on the maximum additional yaw torque that the left and right sides can provide;

[0154] The execution torque determination unit is used to distribute the execution torque of each wheel execution component based on the distribution coefficient determined by the vehicle's required additional yaw torque and the maximum additional total yaw torque.

[0155] In summary, for the maximum additional yaw torque distribution method and system of this multi-axle in-wheel motor vehicle, first, based on the remaining available total torque of the left and right in-wheel motors and the remaining available braking torque of the left and right brake calipers, the maximum torque that can be used to enhance the clockwise and counterclockwise rotation tendencies is determined; then, based on the maximum torque that can be used to enhance the clockwise and counterclockwise rotation tendencies, the maximum additional yaw torque that the left and right wheels can provide is determined; then, based on the maximum additional yaw torque that the left and right sides can provide, the maximum additional total yaw torque that the vehicle can provide is determined; based on the distribution coefficient determined by the vehicle's required additional yaw torque and the maximum additional total yaw torque, the execution torque of each in-wheel motor and brake caliper is distributed. By accurately calculating the maximum additional yaw torque that the vehicle can provide, it is ensured that the in-wheel motor and the braking system do not work beyond their capacity, avoiding problems that may cause risks of damaging the in-wheel motor and the braking system, and improving the handling stability and safety of the vehicle. Considering the influence of the vehicle geometry of the multi-axle vehicle and multiple steering axles on the maximum additional yaw torque of the vehicle, the obtained maximum additional yaw torque that can be provided is made more accurate; when distributing the execution torque of each in-wheel motor and brake caliper, at the same time, the torque transformation on the left and right sides is always equal in magnitude and opposite in direction, which ensures that the power performance of the whole vehicle is not changed.

[0156] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0157] The above description is only a specific implementation manner of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for distributing the maximum additional yaw torque of a multi-axis in-wheel motor vehicle, characterized in that, Including the following steps: Based on the remaining available total torque of the left and right hub motors and the remaining available braking torque of the left and right brake calipers, determine the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies; Based on the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies, determine the maximum additional yaw torque that the left and right wheels can provide; Based on the maximum additional yaw torque that the left and right wheels can provide, determine the maximum additional total yaw torque that the vehicle can provide; Based on the distribution coefficient determined by the vehicle required additional yaw torque and the maximum additional total yaw torque, distribute the execution torques of the hub motors and brake calipers of each wheel; The step of determining the maximum additional yaw torque that the left and right wheels can provide based on the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies includes: Based on the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies, determine the torque increase and decrease amounts of the left and right hub motors on each axle and the torque increase and decrease amounts of the brake calipers; Based on the torque increase and decrease amounts of the left and right hub motors on each axle and the torque increase and decrease amounts of the brake calipers, determine the maximum additional yaw torque that the left and right wheels can provide; According to the formula determine the maximum additional yaw moment ΔM that can be provided on the left side l and the maximum additional yaw torque ΔM that can be provided on the right side r ; where, ΔT lmi is the torque increment or decrement of the left hub motor of the i-th axis; ΔT lki is the torque increment or decrement of the left brake caliper of the i-th axis; d i is the distance from the vehicle geometric center to the left or right wheel of the i-th axis; r i is the radius of the wheel corresponding to the i-th axis; ΔT rmi is the torque increment or decrement of the right hub motor of the i-th axis; ΔT rki is the torque increment or decrement of the right brake caliper of the i-th axis; θ li is the angle between the vector connecting the vehicle geometric center to the center of the left wheel of the i-th axis and the resultant vector of ΔT lmi +ΔT lki , θ li ∈[0, 2π]; θ ri is the angle between the vector connecting the vehicle geometric center to the center of the right wheel of the i-th axis and the resultant vector of ΔT rmi +ΔT rki resultant vector, θ ri ∈[0, 2π], n is the number of axes; S is the rotation direction; where, S = 1 in the case of clockwise enhanced rotation of the vehicle, and S = -1 in the case of counterclockwise enhanced rotation of the vehicle.

2. The maximum additional yaw torque distribution method for a multi-axle in-wheel motor vehicle according to claim 1, wherein: The step of determining the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies based on the remaining available total torque of the left and right hub motors and the remaining available braking torque of the left and right brake calipers includes: Based on the remaining available total increase and remaining available total decrease torques of the left and right hub motors and the remaining available braking torque of the left and right brake calipers, determine the maximum total torques that the left and right wheels can respectively provide to make the vehicle rotate clockwise and counterclockwise around the geometric center; Based on the maximum total torques that the left and right wheels can respectively provide to make the vehicle rotate clockwise and counterclockwise around the geometric center, determine the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies.

3. The method for distributing the maximum additional yaw torque of a multi-axle hub motor vehicle according to claim 2, characterized in that: According to the formula determine that the left wheel can provide the maximum total torque ΔT for the vehicle to rotate clockwise around the geometric center lmax1 and the maximum total torque ΔT for counterclockwise rotation lmax2 ; According to the formula determine the maximum total torque ΔT that the right wheel can provide to make the vehicle rotate counterclockwise around the geometric center rmax1 and the maximum total torque ΔT for clockwise rotation rmax2 ; According to ΔT min1 = min(ΔT lmax1 , ΔT rmax2 ), determine the maximum torque ΔT min1 ; According to ΔT min2 = min(ΔT lmax2 , ΔT rmax1 ), determine the maximum torque value ΔT min2 that can be used to enhance the counterclockwise rotation trend; Among them, ΔT lmmax1 is the total remaining available incremental torque of the left hub motor, ΔT lmmax2 is the total remaining available decremental torque of the left hub motor, ΔT lkmax is the remaining available braking torque of the left brake caliper, ΔT rmmax1 is the total remaining available incremental torque of the right hub motor, ΔT rmmax2 is the total remaining available decremental torque of the right hub motor, ΔT rkmax is the remaining available braking torque of the right brake caliper.

4. The method for distributing the maximum additional yaw torque of a multi-axle hub motor vehicle according to claim 3, characterized in that: When the vehicle rotates clockwise with increasing speed (S = 1), make ΔT lmi , ΔT lki , ΔT rmi and ΔT rki satisfy: In the case of the vehicle rotating counterclockwise with enhanced rotation (S = -1), make ΔT lmi , ΔT lki , ΔT rmi and ΔT rki satisfy: Based on the above constraint relationships, when the absolute values of ΔM l and ΔM r are maximized respectively, determine the corresponding ΔT lmi , ΔT lki , ΔT rmi and ΔT rki ; Among them, S represents the rotation direction, ΔT lmi is the torque increment and decrement of the left hub motor of the i-th axis, ΔT lki is the torque increment and decrement of the left brake caliper of the i-th axis, ΔT rmi is the torque increment and decrement of the right hub motor of the i-th axis; ΔT rki is the torque increment and decrement of the right brake caliper of the i-th axis; T lmmaxi is the maximum output torque of the left hub motor of the i-th axis, T rmmaxi is the maximum output torque of the right hub motor of the i-th axis, T lmi is the driver intention torque of the left hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rmi is the driver intention torque of the right hub motor of the i-th axis calculated based on the accelerator pedal and the brake pedal, T rkmaxi is the maximum output torque of the right brake caliper of the i-th axis, T lkmaxi is the maximum output torque of the left brake caliper of the i-th axis, T lki is the driver intention torque of the left brake caliper of the i-th axis calculated based on the brake pedal, T rki is the driver intention torque of the right brake caliper of the i-th axis calculated based on the brake pedal, and n is the number of axes.

5. The maximum additional yaw torque distribution method for a multi-axle in-wheel motor vehicle according to claim 1, characterized in that: According to ΔM max = ΔM l + ΔM r , determine the maximum additional total yaw torque ΔM max available for the vehicle.

6. The maximum additional yaw torque distribution method for a multi-axle in-wheel motor vehicle according to claim 5, characterized in that: According to determine the distribution coefficient γ, where ΔM is the additional yaw torque required for the vehicle.

7. The method for distributing the maximum additional yaw torque of a multi-axle hub motor vehicle according to claim 6, characterized in that: According to the formula Determine the execution torque allocated to the in-wheel motors and brake calipers for each round; where, ΔT′ lmi is the torque increment executed by the left hub motor of the i-th axis; ΔT′ rmi is the torque increment executed by the right hub motor of the i-th axis; ΔT′ lki is the torque increment executed by the left brake caliper of the i-th axis; ΔT′ rki is the torque increment executed by the right brake caliper of the i-th axis.

8. A maximum additional yaw torque distribution system for a multi-axis in-wheel motor vehicle, characterized in that, Including: A torque maximum value determination unit, which is used to determine the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies based on the remaining available total torque of the left and right hub motors and the remaining available braking torque of the left and right brake calipers; A wheel-provided yaw torque determination unit, which is used to determine the maximum additional yaw torque that the left and right wheels can provide based on the maximum torque value that can be used to enhance the clockwise and counterclockwise rotation tendencies; A vehicle-provided total yaw torque determination unit, which is used to determine the maximum additional total yaw torque that the vehicle can provide based on the maximum additional yaw torque that the left and right wheels can provide; An execution torque determination unit, which is used to distribute the execution torques of each wheel's execution components based on the distribution coefficient determined by the vehicle required additional yaw torque and the maximum additional total yaw torque; Determining the maximum additional yaw torque that can be provided by the left and right wheels based on the maximum torque that can be used for enhancing the clockwise and counterclockwise rotation trends, includes: Determining the torque increase and decrease amounts of the left and right hub motors on each axle and the torque increase and decrease amounts of the brake calipers according to the maximum torque that can be used for enhancing the clockwise and counterclockwise rotation trends; Determining the maximum additional yaw torque that can be provided by the left and right wheels according to the torque increase and decrease amounts of the left and right hub motors on each axle and the torque increase and decrease amounts of the brake calipers; According to the formula determine the maximum additional yaw moment ΔM that can be provided on the left side l and the maximum additional yaw moment ΔM that can be provided on the right side r ; where, ΔT lmi is the torque increment or decrement of the left hub motor of the i-th axle; ΔT lki is the torque increment or decrement of the left brake caliper of the i-th axle; d i is the distance from the vehicle's geometric center to the left or right wheel of the i-th axle; r i is the radius of the wheel corresponding to the i-th axle; ΔT rmi is the torque increment or decrement of the right hub motor of the i-th axle; ΔT rki is the torque increment or decrement of the right brake caliper of the i-th axle; θ li is the angle between the vector connecting the vehicle's geometric center to the center of the left wheel of the i-th axle and the resultant vector of ΔT lmi +ΔT lki , θ li ∈[0, 2π]; θ ri is the angle between the vector connecting the vehicle's geometric center to the center of the right wheel of the i-th axle and the resultant vector of ΔT rmi +ΔT rki resultant vector, θ ri ∈[0, 2π], n is the number of axles; S is the rotation direction; where, S = 1 when the vehicle rotates clockwise and S = -1 when the vehicle rotates counterclockwise.

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