CN115139811A - Torque distribution method and device - Google Patents

Torque distribution method and device Download PDF

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Publication number
CN115139811A
CN115139811A CN202110352484.6A CN202110352484A CN115139811A CN 115139811 A CN115139811 A CN 115139811A CN 202110352484 A CN202110352484 A CN 202110352484A CN 115139811 A CN115139811 A CN 115139811A
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China
Prior art keywords
torque
vehicle
equivalent
initial
wheel
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CN202110352484.6A
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Chinese (zh)
Inventor
张霏霏
谷靖
王连旭
王林
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SAIC Motor Corp Ltd
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SAIC Motor Corp Ltd
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Priority to CN202110352484.6A priority Critical patent/CN115139811A/en
Publication of CN115139811A publication Critical patent/CN115139811A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/24—Steering angle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/46—Drive Train control parameters related to wheels
    • B60L2240/461—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/46—Drive Train control parameters related to wheels
    • B60L2240/463—Torque

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Arrangement And Driving Of Transmission Devices (AREA)

Abstract

The application discloses a torque distribution method and a device, comprising the following steps: acquiring an actual wheel speed, a vehicle yaw rate and a steering wheel angle of each driving wheel of the vehicle, and calculating an equivalent wheel speed of each driving wheel based on the acquired actual wheel speed, the vehicle yaw rate and the steering wheel angle; if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, adjusting a first initial torque distributed to a front axle of the vehicle to a first target torque and adjusting a second initial torque distributed to the vehicle to a second target torque according to the equivalent wheel speeds of the driving wheels. Therefore, the torque distributed to the front axle and the rear axle of the vehicle is adjusted, so that the rotation speed of the axle can be timely reduced after the rotation speed is increased, the influence of the increase of the rotation speed of the axle on the steering of the vehicle is further reduced, and the stability of the vehicle is improved.

Description

Torque distribution method and device
Technical Field
The present disclosure relates to torque distribution technologies, and in particular, to a torque distribution method and apparatus.
Background
In a four-wheel drive vehicle, the torque output by the engine can be distributed to the front and rear four driving wheels according to a certain proportion, so that each driving wheel of the vehicle can obtain power, and the driving wheels are rotated to drive the vehicle to move forwards or backwards.
However, in practical applications, when a vehicle travels on a relatively bad road, the driving wheels may slip. For example, when the vehicle is running on a muddy road, the friction coefficient between the front driving wheel or the rear driving wheel of the vehicle and the muddy ground is small, so that the front driving wheel or the rear driving wheel slips. This causes the rotation speed of the front axle connected to the front drive wheels or the rear axle connected to the rear drive wheels to suddenly increase if the front drive wheels or the rear drive wheels of the vehicle slip while the vehicle is turning, which may affect the driver's control of the turning of the vehicle and reduce the stability of the vehicle.
Disclosure of Invention
The embodiment of the application provides a torque distribution method and a torque distribution device, so that the influence on vehicle steering when a front driving wheel or a rear driving wheel of a vehicle slips is reduced, and the stability of the vehicle is improved.
In a first aspect, an embodiment of the present application provides a torque distribution method, including:
acquiring actual wheel speeds of driving wheels of a vehicle, yaw rate of the vehicle and steering wheel angles;
calculating an equivalent wheel speed of each of the drive wheels based on the actual wheel speed of each of the drive wheels, the vehicle yaw rate, and the steering wheel angle;
if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, adjusting a first initial torque distributed to a front axle of the vehicle to a first target torque and adjusting a second initial torque distributed to a rear axle of the vehicle to a second target torque according to the equivalent wheel speeds of the driving wheels.
In some possible embodiments, the adjusting a first initial torque distributed to a front axle of the vehicle to a first target torque and a second initial torque distributed to a rear axle of the vehicle to a second target torque based on an equivalent wheel speed of each of the driving wheels comprises:
determining a torque transfer ratio based on the equivalent wheel speeds of the respective drive wheels;
calculating the product of the torque transfer proportion and an initial total torque to obtain a transfer torque, wherein the initial total torque is the sum of a first initial torque distributed to a front axle of the vehicle and a second initial torque distributed to a rear axle of the vehicle;
calculating to obtain the first target torque according to the first initial torque and the transfer torque;
and calculating to obtain the second target torque according to the second initial torque and the transfer torque.
In some possible embodiments, the determining the torque transfer ratio based on the equivalent wheel speeds of the respective driving wheels includes:
calculating an equivalent rotation speed difference between a first equivalent rotation speed of the front axle and a second equivalent rotation speed of the rear axle, wherein the first equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the front axle, and the second equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the rear axle;
determining the torque transfer proportion according to a preset corresponding relation between the equivalent rotation speed difference and the torque transfer proportion, or determining the torque transfer proportion according to a preset corresponding relation between a change rate of the equivalent rotation speed difference and the torque transfer proportion, wherein the change rate is obtained by carrying out differential operation on the equivalent rotation speed difference.
In some possible embodiments, the adjusting the first initial torque allocated to the front axle of the vehicle to a first target torque and the adjusting the second initial torque allocated to the rear axle of the vehicle to a second target torque comprises:
determining the friction capacity grade of the current running road surface of the vehicle;
if the friction capacity level is characterized as high, gradually adjusting the first initial torque to a first target torque within a first time period, and gradually adjusting the second initial torque to a second target torque within the first time period;
if the friction capacity level is characterized as low, gradually adjusting the first initial torque to a first target torque in a second time period, and gradually adjusting the second initial torque to a second target torque in the second time period;
wherein the duration of the first time period is less than the duration of the second time period.
In some possible embodiments, the method further comprises:
if the first target torque is determined to exceed a first maximum torque limit corresponding to the front axle, adjusting the torque distributed to the front axle from the first target torque to the first maximum torque limit;
and/or if the second target torque is determined to exceed a second maximum torque limit value corresponding to the rear axle, adjusting the torque distributed to the front axle from the second target torque to the second maximum torque limit value.
In a second aspect, embodiments of the present application further provide a torque distribution device, including:
the device comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the actual wheel speed, the vehicle yaw rate and the steering wheel angle of each driving wheel of the vehicle;
a calculation module for calculating an equivalent wheel speed of each of the drive wheels based on an actual wheel speed of each of the drive wheels, the vehicle yaw rate, and the steering wheel angle;
the distribution module is used for adjusting a first initial torque distributed to a front axle of the vehicle to be a first target torque and adjusting a second initial torque distributed to a rear axle of the vehicle to be a second target torque according to the equivalent wheel speeds of the driving wheels if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range.
In some possible embodiments, the allocation module includes:
a first determination unit for determining a torque transfer ratio based on equivalent wheel speeds of the respective drive wheels;
a first calculation unit, configured to calculate a product of the torque transfer ratio and an initial total torque, resulting in a transfer torque, where the initial total torque is a sum of a first initial torque allocated to a front axle of the vehicle and a second initial torque allocated to a rear axle of the vehicle;
the second calculation unit is used for calculating the first target torque according to the first initial torque and the transfer torque;
and the third calculating unit is used for calculating the second target torque according to the second initial torque and the transfer torque.
In some possible embodiments, the first determining unit includes:
the calculating subunit is configured to calculate an equivalent rotation speed difference between a first equivalent rotation speed of the front axle and a second equivalent rotation speed of the rear axle, where the first equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the front axle, and the second equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the rear axle;
and the determining subunit is configured to determine the torque transfer proportion according to a preset corresponding relationship between the equivalent rotational speed difference and the torque transfer proportion, or determine the torque transfer proportion according to a preset corresponding relationship between a change rate of the equivalent rotational speed difference and the torque transfer proportion, where the change rate is obtained by performing differential operation on the equivalent rotational speed difference.
In some possible embodiments, the allocation module includes:
a second determination unit configured to determine a friction capability level of a road surface on which the vehicle is currently running;
if the friction capacity level is characterized as high, gradually adjusting the first initial torque to a first target torque within a first time period, and gradually adjusting the second initial torque to a second target torque within the first time period;
an adjusting unit, configured to gradually adjust the first initial torque to a first target torque within a second time period and gradually adjust the second initial torque to a second target torque within the second time period if the friction capacity level is characterized as low;
wherein the duration of the first time period is less than the duration of the second time period.
In some possible embodiments, the apparatus further comprises:
the first adjusting module is used for adjusting the torque distributed to the front axle from the first target torque to a first maximum torque limit value if the first target torque is determined to exceed the first maximum torque limit value corresponding to the front axle;
and/or the presence of a gas in the gas,
and the second adjusting module is used for adjusting the torque distributed to the front axle from the second target torque to a second maximum torque limit value if the second target torque is determined to exceed the second maximum torque limit value corresponding to the rear axle.
In the implementation manner of the embodiment of the present application, during the running process of the vehicle, the actual wheel speed, the vehicle yaw rate and the steering wheel angle of each driving wheel (i.e. the left front driving wheel, the right front driving wheel, the left rear driving wheel and the right rear driving wheel) of the vehicle may be acquired, and the equivalent wheel speed of each driving wheel may be calculated based on the acquired actual wheel speed, the vehicle yaw rate and the steering wheel angle; if the difference value between the equivalent wheel speeds of the driving wheels exceeds the preset range, which indicates that the driving wheels slip currently, the first initial torque distributed to the front axle of the vehicle can be adjusted to the first target torque, and the second initial torque distributed to the vehicle can be adjusted to the second target torque according to the equivalent wheel speeds of the driving wheels. Therefore, when the fact that the current driving wheel slips is determined based on the equivalent wheel speed of each driving wheel, the torque distributed to the front axle and the rear axle of the vehicle is adjusted, the wheel speed of the slipping driving wheel can be reduced under the action of the adjusted torque, and the wheel speed of the driving wheel without slipping can be correspondingly increased under the action of the adjusted torque, so that the rotating speed of the axle can be timely reduced after the rotating speed of the axle is increased, and the influence of the increase of the rotating speed of the axle on the steering of the vehicle is further reduced; also, adjusting the torque of the front axle and the rear axle can balance the wheel speeds of the respective driving wheels, so that the stability of the vehicle can be improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art according to the drawings.
FIG. 1 is a schematic flow chart of a torque distribution method according to an embodiment of the present disclosure;
FIG. 2 is a schematic vehicle steering diagram;
fig. 3 is a schematic structural diagram of a torque distribution device in an embodiment of the present application.
Detailed Description
In practical applications, four-wheel drive vehicles (such as electric four-wheel drive vehicles using pure electric four-wheel drive systems) are inevitably slippery when driving on some road conditions. When the driving wheel of the vehicle slips, the speed of the driving wheel suddenly increases, so that the axle corresponding to the driving wheel also suddenly increases, and the steering of the vehicle may be affected. Specifically, according to the tire friction circle theory, there is a close relationship between the driving wheel slip and the vehicle steering characteristics: when the left rear driving wheel or the right rear driving wheel of the vehicle slips, the wheel speed of the left rear driving wheel or the right rear driving wheel is increased, so that the rotating speed of a rear axle of the vehicle is suddenly increased, and the vehicle is easy to oversteer; when the left front driving wheel or the right front driving wheel of the vehicle slips, the rotation speed of the front axle of the vehicle is suddenly increased due to the increase of the wheel speed of the left front driving wheel or the right front driving wheel, and therefore the vehicle is easy to have insufficient steering. Whether oversteer or understeer, the steering control of the vehicle by the driver is affected, reducing the stability of the vehicle.
Based on this, the embodiment of the application provides a torque distribution method, which can reduce the influence on the vehicle steering when the front driving wheels or the rear driving wheels of the vehicle slip by adjusting the torque distributed to the front axle and the rear axle of the vehicle, and improve the stability of the vehicle. Specifically, during the running of the vehicle, the actual wheel speeds, the vehicle yaw rates and the steering wheel angles of the respective driving wheels (i.e., the left front driving wheel, the right front driving wheel, the left rear driving wheel and the right rear driving wheel) of the vehicle may be acquired, and the equivalent wheel speeds of the respective driving wheels may be calculated based on the acquired actual wheel speeds, the vehicle yaw rates and the steering wheel angles; if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, which indicates that the driving wheels slip currently, the first initial torque distributed to the front axle of the vehicle can be adjusted to the first target torque, and the second initial torque distributed to the vehicle can be adjusted to the second target torque according to the equivalent wheel speeds of the driving wheels. Therefore, when the fact that the driving wheels slip is determined to exist currently based on the equivalent wheel speeds of the driving wheels is determined, the torques distributed to the front axle and the rear axle of the vehicle are adjusted, so that the slipping driving wheels can reduce the wheel speeds under the adjusted torque action, and the driving wheels without slipping can correspondingly increase the wheel speeds under the adjusted torque action, so that the rotating speeds of the axles can be timely reduced after the rotating speeds of the axles are increased, and further, the influence of the increase of the rotating speeds of the axles on the steering of the vehicle is reduced; also, adjusting the torque of the front axle and the rear axle can balance the wheel speeds of the respective driving wheels, so that the stability of the vehicle can be improved.
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, various non-limiting embodiments accompanying the present application examples are described below with reference to the accompanying drawings. It should be apparent that the embodiments described are some, but not all embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 shows a schematic flow chart of a torque distribution method in an embodiment of the present application, which may specifically include:
s101: an actual wheel speed, a vehicle yaw rate, and a steering wheel angle of each drive wheel of the vehicle are obtained.
S102: based on the actual wheel speed, the vehicle yaw rate, and the steering wheel angle of each drive wheel, an equivalent wheel speed of each drive wheel is calculated.
In practical applications, the vehicle may have different wheel speeds of the driving wheels due to some operating conditions. Specifically, in one example operating condition, when the front and rear driving wheels of the four-wheel-drive vehicle are on different road surfaces, the wheel speed of the driving wheel on the ground with lower adhesive force is relatively high, and the wheel speed of the driving wheel on the ground with lower adhesive force is relatively low. The traction of the ground can be embodied as a coefficient of friction between the ground drive wheels, i.e. the larger the coefficient of friction, the higher the traction, the smaller the coefficient of friction, and the lower the traction.
In another example operating condition, when torque output from an engine in a vehicle is distributed to front and rear axles, if the torque distributed to the front and rear axles is inappropriate, for example, the torque distributed to the front and rear axles is relatively different, the wheel speed of a driving wheel distributed to a larger torque based on the axle is relatively higher, and the wheel speed of a driving wheel distributed to a smaller torque based on the axle is relatively lower. In yet another exemplary operating condition, the vehicle may experience load shifting to the outside due to driver rough driving, thereby making the inboard drive wheels prone to higher wheel speeds due to insufficient ground adhesion. Of course, in practical applications, specific operating conditions that cause differences between the wheel speeds of the respective driving wheels include, but are not limited to, the above three examples.
Although the vehicle has different wheel speeds of the front and rear driving wheels under the above-mentioned operating conditions, that is, different rotating speeds of the front and rear axles of the vehicle, the influence of these operating conditions on the vehicle steering can be usually overcome based on the current vehicle design. However, when the unintended slip of the driving wheels of the vehicle occurs, the rotational speed between the front and rear axles of the vehicle may be greatly different, thereby having a serious influence on the steering of the vehicle. Therefore, in the present embodiment, the torque allocated to the front and rear axles of the vehicle is adjusted to reduce the influence of the difference in the rotational speeds of the front and rear axles on the steering of the vehicle, in response to the unexpected abnormality in the steering of the vehicle caused by the slip of the drive wheels.
It will be appreciated that, due to the difference in turning radii, the wheel speed of the front drive wheels is typically higher than the rotational speed of the rear drive wheels, and the wheel speed of the outboard drive wheels is higher than the wheel speed of the inboard drive wheels, even though all of the drive wheels are in a pure rolling condition (i.e., non-slipping condition) during vehicle steering. Therefore, in the embodiment, the equivalent wheel speed corresponding to the actual wheel speed of each driving wheel can be calculated according to the current motion parameter of the vehicle, so as to determine whether the driving wheel slips during the steering process of the vehicle by using the calculated equivalent wheel speed of each driving wheel.
Specifically, the actual wheel speed, the vehicle yaw rate and the steering wheel angle of each driving wheel of the current vehicle may be obtained first, and the equivalent wheel speed of each driving wheel in the vehicle centroid position in the vehicle head direction may be calculated based on the obtained actual wheel speed, the obtained vehicle yaw rate and the obtained steering wheel angle of each driving wheel. Thus, if the equivalent wheel speeds of the driving wheels are basically the same, the fact that the driving wheels do not slip in the current steering process of the vehicle is indicated, and the torque distributed to the front axle and the rear axle is not required to be adjusted; if there is a large difference between the equivalent wheel speeds of the driving wheels, for example, if there is a driving wheel with an equivalent wheel speed significantly higher than the equivalent wheel speeds of the other three driving wheels, it indicates that the driving wheel is slipping during the current steering process of the vehicle, and the slipping driving wheel may be the driving wheel with the largest equivalent wheel speed.
In an exemplary embodiment, as shown in fig. 2, the wheel speed of each driving wheel of the four-wheel drive vehicle may be measured using a wheel speed sensor, and the yaw rate and the steering wheel angle of the vehicle may be measured using a yaw rate sensor and a steering wheel angle sensor, respectively, and then, the equivalent wheel speed of each driving wheel may be calculated using equations (1) to (4), respectively.
W LeFr_C ＝cosσ LeFr *W LeFr +0.5*Φ*B Fr (1)
W RiFr_C ＝cosσ RiFr *W RiFr -0.5*Φ*B Fr (2)
W LeRr_C ＝W LeRr +0.5*Φ*B Rr (3)
W RiRr_C ＝W RiRr -0.5*Φ*B Rr (4)
Wherein "W LeFr_C ”、“W RiFr_C ”、“W LeRr_C ”“W RiRr_C "equivalent wheel speeds of the left front drive wheel, the right front drive wheel, the left rear drive wheel and the right rear drive wheel of the vehicle," W LeFr ”、“W RiFr ”、“W LeRr ”“W RiRr "actual wheel speeds of the vehicle's left front drive wheel, right front drive wheel, left rear drive wheel, and right rear drive wheel, respectively," σ LeFr ”、“σ RiFr "the rotation angles of the left and right front wheels (i.e. the rotation angle of the steering wheel, defining the counterclockwise direction as positive)," phi "is the yaw rate of the vehicle," B Fr ”、“B Rr "the track widths of the front and rear axles (i.e., the track width between the front left and right drive wheels, and the track widths of the rear left and right drive wheels, respectively, and the track widths are generally fixed values for a particular vehicle).
S103: if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, adjusting a first initial torque distributed to a front axle of the vehicle to a first target torque and adjusting a second initial torque distributed to a rear axle of the vehicle to a second target torque according to the equivalent wheel speeds of the driving wheels.
In this embodiment, after calculating the equivalent wheel speeds of the driving wheels, a difference between the equivalent wheel speeds of the driving wheels may be further calculated, or a difference between the maximum equivalent wheel speed and the minimum equivalent wheel speed may be further calculated, and it is determined whether the difference exceeds a preset range. If so, indicating that the driving wheel slips at present, and adjusting the torque distributed to the front axle and the rear axle; if not, indicating that no slipping of the drive wheels is currently present, the torque allocated to the front and rear axles may not be adjusted.
It is understood that when the four driving wheels of the vehicle are in a pure rolling state, although the calculated equivalent wheel speeds of the respective driving wheels should be equal theoretically, in practical applications, there will be a small difference in the calculated equivalent wheel speeds of the respective driving wheels due to calculation errors and the like even if none of the four driving wheels slip. Based on this, in the present embodiment, a range may be preset, and when it is determined that the error between the equivalent wheel speeds of the respective drive wheels is within the preset range, there is no occurrence of the slip of the drive wheels, and when the error between the equivalent wheel speeds of the respective drive wheels exceeds the preset range, there is occurrence of the slip of the drive wheels, so as to improve the robustness of the torque distribution strategy.
In the present embodiment, a part of the torque output by the engine (i.e., the first initial torque) is distributed to the front axle so that the front axle transmits the part of the torque to the left front driving wheel and the right front driving wheel and acts on the left front driving wheel and the right front driving wheel to cause the left front driving wheel and the right front driving wheel to rotate; another portion (i.e., the second initial torque) is distributed to the rear axle so that the rear axle transmits the portion of torque to and acts on the left and right rear drive wheels to cause rotation thereof. However, when there is a slip of the drive wheels, the torque output from the engine is distributed based on the first initial torque and the second initial torque, so that the vehicle may be oversteered or understeered. Therefore, in the present embodiment, in order to avoid this, the first initial torque may be adjusted to the first target torque, and the second initial torque may be adjusted to the second target torque, so that the stability of the vehicle during the steering may be improved after the torque distribution is performed based on the first target torque and the second target torque.
Specifically, if it is determined that the front left drive wheel or the front right drive wheel slips based on the equivalent wheel speeds of the respective drive wheels, the first initial torque may be decreased to a first target torque, and the second initial torque may be increased to a second target torque, so as to decrease the wheel speeds of the front left drive wheel and the front right drive wheel, and increase the wheel speeds of the rear left drive wheel and the rear right drive wheel, thereby improving the stability of the vehicle steering. At this time, the first target torque is larger than the first initial torque, and the second target torque is larger than the second initial torque.
Similarly, if it is determined that the slip of the left rear driving wheel or the right rear driving wheel occurs based on the equivalent wheel speeds of the respective driving wheels, the first initial torque may be increased to the first target torque, the second initial torque may be decreased to the second target torque to increase the wheel speeds of the left front driving wheel and the right front driving wheel and decrease the wheel speeds of the left rear driving wheel and the right rear driving wheel, thereby improving the stability of the vehicle steering. At this time, the first target torque is smaller than the first initial torque, and the second target torque is smaller than the second initial torque.
In an exemplary embodiment, the torque difference between the first initial torque and the first target torque may be equal to the torque difference between the second initial torque and the second target torque, i.e. the partial torque originally allocated to the front axle is transferred and allocated to the rear axle, or the partial torque originally allocated to the rear axle is transferred and allocated to the front axle, and the total torque output by the engine may be unchanged before and after the adjustment. Specifically, the torque transfer ratio may be determined based on the equivalent wheel speeds of the respective drive wheels, and the product of the torque transfer ratio and the initial total torque may be calculated to obtain the transfer torque. Then, when the transfer torque is transferred from the front axle to the rear axle, the first target torque is a difference value between the first initial torque and the transfer torque, and the second target torque is a sum of the second initial torque and the transfer torque; when the transfer torque is transferred from the rear axle to the front axle, the first target torque is the sum of the first initial torque and the transfer torque, and the second target torque is the difference between the second initial torque and the transfer torque. Wherein the initial total torque is the sum of the first initial torque and the second initial torque. Therefore, under the condition of not changing the initial total torque, the torque acting on the slipping driving wheel can be reduced by transferring the torque, and the torque acting on the non-slipping driving wheel is improved, so that the adhesion capacity of the front axle and the rear axle can be more fully utilized, the power loss caused by slipping of the driving wheel is avoided, the power performance of the vehicle is improved, and the stability of the vehicle during steering can be improved; and moreover, the torque transfer proportion is used for determining the transfer torque, so that the degree of the transfer torque under different initial total torque sizes can be considered, and the torque distribution can have a uniform distribution effect. Of course, in other possible embodiments, after adjusting the torque allocated to the front axle and the rear axle, the torque output by the engine may also be changed, i.e., the torque output by the engine may be adaptively increased or decreased.
In a further embodiment of determining the torque transfer ratio, an average value of equivalent wheel speeds corresponding to the driving wheels on both sides of the front axle may be calculated to obtain a first equivalent rotational speed of the front axle, and an average value of equivalent wheel speeds corresponding to the driving wheels on both sides of the rear axle may be calculated to obtain a second equivalent rotational speed of the rear axle, so that an equivalent rotational speed difference between the first equivalent rotational speed and the second equivalent rotational speed may be further calculated; then, the torque transfer ratio may be determined based on a correspondence relationship between the preset equivalent rotational speed difference and the torque transfer ratio, or the equivalent rotational speed difference may be subjected to a differential operation to calculate a change rate of the equivalent rotational speed difference, and the torque transfer ratio may be determined based on a correspondence relationship between the change rate of the equivalent rotational speed difference and the torque transfer ratio that is preset. The correspondence relationship may be preset based on experience of a technician in actual application.
In practice, in order to avoid the adverse effect of the abrupt change of the torque on the driving of the vehicle in the process of increasing or decreasing the distributed torque from the initial torque to the target torque, the initial torque may be gradually increased or decreased to the target torque over a period of time to avoid the unexpected acceleration or deceleration of the vehicle. The specific duration of the torque adjusting period may be determined according to the friction capacity (or the adhesion capacity) of the road surface on which the driving wheels of the vehicle are located.
Specifically, in the process of adjusting the first initial torque to the first target torque and the second initial torque to the second target torque, a friction capacity level of a road surface on which the vehicle is currently running may be determined, and if it is determined that the friction capacity level is high, the first initial torque may be gradually adjusted to the first target torque in a first time period, and the second initial torque may also be gradually adjusted to the second target torque in the first time period; if it is determined that the friction capacity level is characterized as low, the first initial torque may be gradually adjusted to the first target torque over a second time period, and the second initial torque may also be gradually adjusted to the second target torque over the second time period. The duration of the first time period is less than that of the second time period, namely, on a road surface with low friction capacity, the driving wheel needs to slowly bear torque change, so that the adjustment of torque distribution can be completed in a long time period; on the other hand, on a road surface with high friction capacity, the driving wheels can undergo more rapid torque changes, so that the adjustment of the torque distribution can be completed in a relatively short period of time.
Further, in practical applications, the front axle and the rear axle usually have certain torque capacity limits, and the torque allocated to the front axle and the rear axle cannot exceed the maximum torque that can be borne under the current conditions. Thus, in some possible embodiments, when the first initial torque is adjusted to the first target torque and the second initial torque is adjusted to the second target torque, it may be determined whether the first target torque exceeds a first maximum torque limit corresponding to the front axle, and if it is determined that the first target torque exceeds the first maximum torque limit, the torque allocated to the front axle may be adjusted from the first target torque to the first maximum torque limit; and/or determining whether the second target torque exceeds a second maximum torque limit corresponding to the rear axle, and if it is determined that the second target torque exceeds the second maximum torque limit, adjusting the torque allocated to the rear axle from the second target torque to the second maximum torque limit. It can be understood that the torque finally distributed to the front axle and the rear axle is adjusted based on the torque capacity of the front axle and the rear axle, so that the torque finally distributed to the front axle and the rear axle can not exceed the maximum torque which can be borne by the front axle and the rear axle, and the torque distribution can be more reasonable.
In this embodiment, by adjusting the torques distributed to the front axle and the rear axle of the vehicle, the influence on the steering of the vehicle when the front drive wheels or the rear drive wheels of the vehicle slip can be reduced, and the stability of the vehicle can be improved. Specifically, during the running of the vehicle, the actual wheel speeds, the vehicle yaw rates and the steering wheel angles of the respective driving wheels (i.e., the left front driving wheel, the right front driving wheel, the left rear driving wheel and the right rear driving wheel) of the vehicle may be acquired, and the equivalent wheel speeds of the respective driving wheels may be calculated based on the acquired actual wheel speeds, the vehicle yaw rates and the steering wheel angles; if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, which indicates that the driving wheels slip currently, the first initial torque distributed to the front axle of the vehicle can be adjusted to the first target torque, and the second initial torque distributed to the vehicle can be adjusted to the second target torque according to the equivalent wheel speeds of the driving wheels. Therefore, when the fact that the current driving wheel slips is determined based on the equivalent wheel speed of each driving wheel, the torque distributed to the front axle and the rear axle of the vehicle is adjusted, the wheel speed of the slipping driving wheel can be reduced under the action of the adjusted torque, and the wheel speed of the driving wheel without slipping can be correspondingly increased under the action of the adjusted torque, so that the rotating speed of the axle can be timely reduced after the rotating speed of the axle is increased, and the influence of the increase of the rotating speed of the axle on the steering of the vehicle is further reduced; also, adjusting the torque of the front axle and the rear axle can balance the wheel speeds of the respective driving wheels, so that the stability of the vehicle can be improved.
In addition, the embodiment of the application also provides a torque distribution device. Referring to fig. 3, fig. 3 shows a schematic structural diagram of a torque distribution device in an embodiment of the present application, where the device 300 includes:
an obtaining module 301, configured to obtain an actual wheel speed, a vehicle yaw rate, and a steering wheel angle of each driving wheel of a vehicle;
a calculating module 302 for calculating an equivalent wheel speed of each of the drive wheels based on an actual wheel speed of each of the drive wheels, the vehicle yaw rate, and the steering wheel angle;
the allocating module 303 is configured to adjust a first initial torque allocated to a front axle of the vehicle to a first target torque and adjust a second initial torque allocated to a rear axle of the vehicle to a second target torque according to the equivalent wheel speeds of the driving wheels if a difference between the equivalent wheel speeds of the driving wheels exceeds a preset range.
In some possible embodiments, the assigning module 303 includes:
a first determination unit for determining a torque transfer ratio based on equivalent wheel speeds of the respective drive wheels;
a first calculation unit, configured to calculate a product of the torque transfer ratio and an initial total torque, resulting in a transfer torque, where the initial total torque is a sum of a first initial torque allocated to a front axle of the vehicle and a second initial torque allocated to a rear axle of the vehicle;
the second calculation unit is used for calculating the first target torque according to the first initial torque and the transfer torque;
and the third calculating unit is used for calculating the second target torque according to the second initial torque and the transfer torque.
In some possible embodiments, the first determining unit includes:
the calculating subunit is configured to calculate an equivalent rotation speed difference between a first equivalent rotation speed of the front axle and a second equivalent rotation speed of the rear axle, where the first equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the front axle, and the second equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the rear axle;
and the determining subunit is configured to determine the torque transfer proportion according to a preset corresponding relationship between the equivalent rotational speed difference and the torque transfer proportion, or determine the torque transfer proportion according to a preset corresponding relationship between a change rate of the equivalent rotational speed difference and the torque transfer proportion, where the change rate is obtained by performing differential operation on the equivalent rotational speed difference.
In some possible embodiments, the allocating module 303 includes:
a second determination unit configured to determine a friction capability level of a road surface on which the vehicle is currently running;
if the friction capacity level is characterized as high, gradually adjusting the first initial torque to a first target torque within a first time period, and gradually adjusting the second initial torque to a second target torque within the first time period;
an adjusting unit, configured to gradually adjust the first initial torque to a first target torque within a second time period and gradually adjust the second initial torque to a second target torque within the second time period if the friction capacity level is characterized as low;
wherein the duration of the first time period is less than the duration of the second time period.
In some possible embodiments, the apparatus 300 further comprises:
the first adjusting module is used for adjusting the torque distributed to the front axle from the first target torque to a first maximum torque limit value if the first target torque is determined to exceed the first maximum torque limit value corresponding to the front axle;
and/or the presence of a gas in the gas,
and the second adjusting module is used for adjusting the torque distributed to the front axle from the second target torque to a second maximum torque limit value if the second target torque is determined to exceed the second maximum torque limit value corresponding to the rear axle.
In the embodiment, when the fact that the driving wheel slips at present is determined based on the equivalent wheel speed of each driving wheel, the torque distributed to the front axle and the rear axle of the vehicle is adjusted, so that the wheel speed of the driving wheel with slipping can be reduced under the action of the adjusted torque, and the wheel speed of the driving wheel without slipping can be correspondingly increased under the action of the adjusted torque, so that the rotating speed of the axle can be timely reduced after the rotating speed of the axle is increased, and the influence of the increase of the rotating speed of the axle on the steering of the vehicle is reduced; also, adjusting the torque of the front and rear axles may balance the wheel speeds of the respective driving wheels, thereby improving the stability of the vehicle.
The first in the names "first initial torque", "first target torque", "first maximum torque limit", "first time period", etc. mentioned in the embodiments of the present application are only used for name identification and do not represent the first in sequence. The same applies to "second" etc.
As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that all or part of the steps in the above embodiment methods can be implemented by software plus a general hardware platform. Based on such understanding, the technical solution of the present application may be embodied in the form of a software product, which may be stored in a storage medium, such as a read-only memory (ROM)/RAM, a magnetic disk, an optical disk, or the like, and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network communication device such as a router) to execute the method according to the embodiments or some parts of the embodiments of the present application.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, it is relatively simple to describe, and reference may be made to some descriptions of the method embodiment for relevant points. The above-described embodiments of the apparatus are merely illustrative, and the modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, may be located in one position, or may be distributed on a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only an exemplary embodiment of the present application, and is not intended to limit the scope of the present application.

Claims (10)

1. A method of torque distribution, the method comprising:
acquiring actual wheel speeds of driving wheels of a vehicle, yaw rate of the vehicle and steering wheel angles;
calculating an equivalent wheel speed of each of the drive wheels based on the actual wheel speed of each of the drive wheels, the vehicle yaw rate, and the steering wheel angle;
if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range, adjusting a first initial torque distributed to a front axle of the vehicle to a first target torque and adjusting a second initial torque distributed to a rear axle of the vehicle to a second target torque according to the equivalent wheel speeds of the driving wheels.
2. The method of claim 1, wherein adjusting a first initial torque allocated to a front axle of the vehicle to a first target torque and a second initial torque allocated to a rear axle of the vehicle to a second target torque based on an equivalent wheel speed of each of the driven wheels comprises:
determining a torque transfer ratio based on the equivalent wheel speeds of the respective drive wheels;
calculating the product of the torque transfer proportion and an initial total torque to obtain a transfer torque, wherein the initial total torque is the sum of a first initial torque distributed to a front axle of the vehicle and a second initial torque distributed to a rear axle of the vehicle;
calculating to obtain the first target torque according to the first initial torque and the transfer torque;
and calculating to obtain the second target torque according to the second initial torque and the transfer torque.
3. The method of claim 2, wherein said determining a torque transfer ratio based on an equivalent wheel speed for each of said drive wheels comprises:
calculating an equivalent rotation speed difference between a first equivalent rotation speed of the front axle and a second equivalent rotation speed of the rear axle, wherein the first equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the front axle, and the second equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the rear axle;
determining the torque transfer proportion according to a preset corresponding relation between the equivalent rotation speed difference and the torque transfer proportion, or determining the torque transfer proportion according to a preset corresponding relation between a change rate of the equivalent rotation speed difference and the torque transfer proportion, wherein the change rate is obtained by carrying out differential operation on the equivalent rotation speed difference.
4. The method of claim 1, wherein adjusting a first initial torque allocated to a front axle of the vehicle to a first target torque and a second initial torque allocated to a rear axle of the vehicle to a second target torque comprises:
determining the friction capacity grade of the current running road surface of the vehicle;
if the friction capacity level is characterized as high, gradually adjusting the first initial torque to a first target torque within a first time period, and gradually adjusting the second initial torque to a second target torque within the first time period;
if the friction capacity level is characterized as low, gradually adjusting the first initial torque to a first target torque in a second time period, and gradually adjusting the second initial torque to a second target torque in the second time period;
wherein the duration of the first time period is less than the duration of the second time period.
5. The method according to any one of claims 1 to 4, further comprising:
if the first target torque is determined to exceed a first maximum torque limit corresponding to the front axle, adjusting the torque distributed to the front axle from the first target torque to the first maximum torque limit;
and/or if the second target torque is determined to exceed a second maximum torque limit value corresponding to the rear axle, adjusting the torque distributed to the front axle from the second target torque to the second maximum torque limit value.
6. A torque distribution device, the device comprising:
the device comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the actual wheel speed, the vehicle yaw rate and the steering wheel angle of each driving wheel of the vehicle;
a calculation module for calculating an equivalent wheel speed of each of the drive wheels based on an actual wheel speed of each of the drive wheels, the vehicle yaw rate, and the steering wheel angle;
the distribution module is used for adjusting a first initial torque distributed to a front axle of the vehicle to be a first target torque and adjusting a second initial torque distributed to a rear axle of the vehicle to be a second target torque according to the equivalent wheel speeds of the driving wheels if the difference value between the equivalent wheel speeds of the driving wheels exceeds a preset range.
7. The apparatus of claim 6, wherein the assignment module comprises:
a first determination unit for determining a torque transfer ratio based on the equivalent wheel speeds of the respective drive wheels;
a first calculation unit, configured to calculate a product of the torque transfer ratio and an initial total torque, resulting in a transfer torque, where the initial total torque is a sum of a first initial torque allocated to a front axle of the vehicle and a second initial torque allocated to a rear axle of the vehicle;
the second calculation unit is used for calculating the first target torque according to the first initial torque and the transfer torque;
and the third calculating unit is used for calculating the second target torque according to the second initial torque and the transfer torque.
8. The apparatus of claim 7, wherein the first determining unit comprises:
the calculating subunit is configured to calculate an equivalent rotation speed difference between a first equivalent rotation speed of the front axle and a second equivalent rotation speed of the rear axle, where the first equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the front axle, and the second equivalent rotation speed is an average value of equivalent wheel speeds corresponding to driving wheels on two sides of the rear axle;
the determining subunit is configured to determine the torque transfer ratio according to a preset correspondence between the equivalent rotational speed difference and the torque transfer ratio, or determine the torque transfer ratio according to a preset correspondence between a change rate of the equivalent rotational speed difference and the torque transfer ratio, where the change rate is obtained by performing a differential operation on the equivalent rotational speed difference.
9. The apparatus of claim 6, wherein the assignment module comprises:
a second determination unit configured to determine a friction capability level of a road surface on which the vehicle is currently running;
if the friction capacity level is characterized as high, gradually adjusting the first initial torque to a first target torque within a first time period, and gradually adjusting the second initial torque to a second target torque within the first time period;
an adjusting unit, configured to gradually adjust the first initial torque to a first target torque within a second time period and gradually adjust the second initial torque to a second target torque within the second time period if the friction capacity level is characterized as low;
wherein the duration of the first time period is less than the duration of the second time period.
10. The apparatus of any one of claims 6 to 9, further comprising:
a first adjusting module, configured to adjust a torque allocated to the front axle from the first target torque to a first maximum torque limit value corresponding to the front axle if it is determined that the first target torque exceeds the first maximum torque limit value;
and/or the presence of a gas in the atmosphere,
and the second adjusting module is used for adjusting the torque distributed to the front axle from the second target torque to a second maximum torque limit value if the second target torque is determined to exceed the second maximum torque limit value corresponding to the rear axle.
CN202110352484.6A 2021-03-31 2021-03-31 Torque distribution method and device Pending CN115139811A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110352484.6A CN115139811A (en) 2021-03-31 2021-03-31 Torque distribution method and device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110352484.6A CN115139811A (en) 2021-03-31 2021-03-31 Torque distribution method and device

Publications (1)

Publication Number Publication Date
CN115139811A true CN115139811A (en) 2022-10-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110352484.6A Pending CN115139811A (en) 2021-03-31 2021-03-31 Torque distribution method and device

Country Status (1)

Country Link
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115972927A (en) * 2023-02-22 2023-04-18 成都赛力斯科技有限公司 Antiskid torque control method, device, equipment and storage medium

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115972927A (en) * 2023-02-22 2023-04-18 成都赛力斯科技有限公司 Antiskid torque control method, device, equipment and storage medium

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