CN114590316B - Torque distribution method and equipment for four-wheel drive-by-wire and steering vehicle - Google Patents

Torque distribution method and equipment for four-wheel drive-by-wire and steering vehicle Download PDF

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Publication number
CN114590316B
CN114590316B CN202210309996.9A CN202210309996A CN114590316B CN 114590316 B CN114590316 B CN 114590316B CN 202210309996 A CN202210309996 A CN 202210309996A CN 114590316 B CN114590316 B CN 114590316B
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wheel
vehicle
driving force
longitudinal
ist
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CN114590316A (en
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茅澍州
徐向敏
徐桂红
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Zhiji Automobile Technology Co Ltd
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Zhiji Automobile Technology Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/002—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/008—Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention aims to provide a torque distribution method and equipment for a four-wheel drive-by-wire and steering vehicle, which are based on the actual running state of the vehicle
Figure 255936DEST_PATH_IMAGE001
And a preset accelerator pedal opening ratio
Figure 275844DEST_PATH_IMAGE002
Opening ratio of brake pedal
Figure 12856DEST_PATH_IMAGE003
Steering wheel angle
Figure 192034DEST_PATH_IMAGE004
Determining a desired generalized driving force required for driving a vehicle
Figure 153036DEST_PATH_IMAGE005
And ideal operating conditions of the vehicle
Figure 129083DEST_PATH_IMAGE006
The method comprises the steps of carrying out a first treatment on the surface of the According to the expected generalized driving force
Figure 341889DEST_PATH_IMAGE007
And expects to withstand tire driving forces
Figure 250940DEST_PATH_IMAGE008
Optimally distributing the desired longitudinal and lateral driving forces of each wheel
Figure 586106DEST_PATH_IMAGE009
The method comprises the steps of carrying out a first treatment on the surface of the Based on the desired longitudinal and lateral driving forces of the wheels
Figure 218424DEST_PATH_IMAGE010
Actual wheel speed
Figure 93976DEST_PATH_IMAGE011
And actual wheel angle
Figure 264058DEST_PATH_IMAGE012
Ideal running state of vehicle
Figure 301284DEST_PATH_IMAGE013
And desired vertical load
Figure 251922DEST_PATH_IMAGE014
Calculating desired wheel torque
Figure 55799DEST_PATH_IMAGE015
And wheel corner
Figure 939441DEST_PATH_IMAGE016
The method comprises the steps of carrying out a first treatment on the surface of the Based on wheel torque
Figure 350831DEST_PATH_IMAGE017
Controlling a drive system of a vehicle based on wheel turning angle
Figure 195290DEST_PATH_IMAGE018
The invention can realize that the vehicle runs in the optimal posture and ensure the stability of the vehicle.

Description

Torque distribution method and equipment for four-wheel drive-by-wire and steering vehicle
Technical Field
The invention relates to a torque distribution method and equipment for a four-wheel drive-by-wire and steering vehicle.
Background
The traditional vehicle adopts a torque distribution algorithm with fixed proportion, so that the adhesion coefficient of the road surface can not be effectively utilized when the vehicle runs on split road surfaces, and the stability of the vehicle is easily affected.
Disclosure of Invention
An object of the present invention is to provide a torque distribution method and apparatus for four-wheel drive-by-wire and steering vehicles.
According to one aspect of the present invention, there is provided a torque distribution method of a four-wheel drive-by-wire and steering vehicle, the method comprising:
based on the actual operating state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desire for driving of a vehicleGeneralized driving force u d And ideal vehicle operating state x d ；
According to the expected generalized driving force u d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d ；
Based on the desired longitudinal and lateral driving forces F of the wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d ；
Based on desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
Further, in the above method, the longitudinal and lateral driving forces F are expected based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Before, still include:
according to the actual vertical motion state y fed back by the vehicle v，ist Calculating the desired vertical load F z，d 。
Further, in the above method, according to the actual vertical motion state y fed back by the vehicle v，ist Calculating the desired vertical load F z，d Comprising:
the following vertical dynamics equation is obtained in the time domain:
Figure GDA0004159696090000021
wherein G is v1 (p)、G v2 (p)、G v3 (p) is a transfer function with the vertical displacement of the mass center of the vehicle body, the roll angle of the vehicle body and the pitch angle of the vehicle body as output, w v (p) is the suspension active force transfer function, z v (p) vertical movement due to external disturbance forceA mechanical transfer function; g vi And (p) is a minimum phase system consisting of vehicle parameters such as vehicle mass, suspension rigidity, damping, wheelbase and the like, and in order to improve the steady-state accuracy of control, the following PID controllers are adopted:
Figure GDA0004159696090000022
wherein T is N To adjust the time; τ D Is a low-pass time constant;
in the running process of the vehicle, the expected vertical displacement, the expected roll angle and the expected pitch angle of the vehicle body are all 0, so the expected vertical load F z，d The following are provided:
F z，d ＝f v (0，ΔF z )＝V + w v +F z，F0 ，
wherein f v () Represents the vertical direction function, ΔF z For the main force vector of the suspension, F z，F0 Is static vertical load vector, w v Is the stress vector of the vertical plane of the mass center of the vehicle body, V + Is the generalized inverse of the vertical control efficiency matrix V; from y v，ist Can obtain the stress vector w of the vertical plane of the mass center of the vehicle body v ，y v，ist Is y v (p)，y v (p) by w in body motion control v (p) p, p being the transfer function.
Further, in the above method, the desired generalized driving force u required for running the vehicle d Comprising: desired longitudinal driving force
Figure GDA0004159696090000023
Desired lateral driving force +.>
Figure GDA0004159696090000024
And a desired yaw moment M zd 。
Further, in the above method, the desired longitudinal driving force
Figure GDA0004159696090000025
The determination is based on the following formula:
Figure GDA0004159696090000026
wherein F is xD For the longitudinal driving component, F xB Alpha, being the longitudinal braking component B C is the brake pedal opening ratio s Approximating the parameters for the symbols;
F xD ＝f D (α G )·F xDmax ；
wherein f xDmax For maximum driving force achievable by the vehicle, alpha G Is the accelerator pedal opening ratio.
Further, in the above method, the desired lateral driving force
Figure GDA0004159696090000031
According to the following formula:
Figure GDA0004159696090000032
wherein m is the mass of the whole vehicle, l is the wheelbase of the vehicle, EG is the vehicle stability factor, delta SW For steering wheel angle, v x Is the vehicle longitudinal speed.
Further, in the above method, the desired yaw moment M zd According to the following formula:
Figure GDA0004159696090000033
wherein a is 1 、a 0 Is the dynamic characteristic parameter of the centroid slip angle,
Figure GDA0004159696090000034
for the desired longitudinal speed>
Figure GDA0004159696090000035
For the desired transverse speed>
Figure GDA0004159696090000036
Desired yaw angle for vehicle, < >>
Figure GDA0004159696090000037
Ideal vehicle operating state x for desired lateral driving force d Comprising the following steps: vehicle desired longitudinal speed>
Figure GDA0004159696090000038
Vehicle desired lateral speed>
Figure GDA0004159696090000039
And the desired yaw angle of the vehicle->
Figure GDA00041596960900000310
Further, in the above method, the generalized driving force u is calculated according to the desired d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d Comprising:
setting a first target, wherein the first target can be expressed by the following mathematical formula:
Figure GDA00041596960900000311
wherein W is 1 The third-order diagonal matrix is used for describing the weight of the influence of the longitudinal force, the lateral force and the yaw moment on the first target;F xy to achieve the lower limit value of the tire driving force,
Figure GDA00041596960900000312
an upper limit value for the tire driving force that can be achieved; g is a control efficiency matrix;
setting a second target, wherein the target function and constraint conditions of the second target are as follows:
min max(η i )
s.t.0≤η i ≤1 i＝1...4，
wherein eta i The tire utilization is determined by the actual driving force F of the tire i And a maximum expected driving force F max，i，d I is the wheel number;
the maximum utilization rate of the tire is simplified as follows:
Figure GDA0004159696090000041
according to the first and second objectives, an optimized objective function is obtained:
Figure GDA0004159696090000042
Figure GDA0004159696090000043
f Fi (F xy )≤η max F max，id ， i＝1...4，
0≤η max ≤1
selecting new optimization variable x= [ eta ] max F xy ] T The objective function and constraints are further rewritten as:
Figure GDA0004159696090000044
Figure GDA0004159696090000045
f Fi，e (x)-c T xF max，id ≤0， i＝1...4，
the method meets the following conditions:
Figure GDA0004159696090000046
introducing a motor failure factor epsilon into an optimized objective function i The optimization objective function is as follows:
Figure GDA0004159696090000051
Figure GDA0004159696090000052
f Fi，e (x)-c T xε i F max，id ≤0， i＝1...4，
wherein the optimal solution of x is the expected longitudinal and lateral driving force F of each wheel xy，d 。
Further, in the above method, the longitudinal and lateral driving forces F are expected based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
the desired wheel slip ratio is formulated as follows:
Figure GDA0004159696090000053
wherein the maximum expected driving force F max，i，d The method comprises the following steps:
Figure GDA0004159696090000054
wherein mu is i For road adhesion coefficient B i ，C i Is the coefficient of the magic formula of the tire,
Figure GDA0004159696090000057
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Represents the vertical load of a standard tire, F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
obtaining the wheel rotation speed according to the formula of the vehicle speed and the expected wheel slip rate
Figure GDA0004159696090000055
Is calculated according to the formula:
Figure GDA0004159696090000056
wherein S is xi，d Indicating the desired longitudinal slip ratio S yi，d Indicating the desired lateral slip rate, r wheel Representing the radius of the wheel, v xi，d Indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
adding an inertia link to the rotation speed to obtain the expected wheel rotation speed omega of the ith wheel i，d The method comprises the following steps:
Figure GDA0004159696090000061
wherein p represents a transfer function, T ω Indicating the time constant of the rotational speed of the wheel,
Figure GDA0004159696090000062
representation->
Figure GDA0004159696090000063
Is a laplace transform of (a);
from the tire dynamics model, it is obtained:
Figure GDA0004159696090000064
wherein f R () As a wheel direction function, ω is a rotational angular velocity vector of each wheel; delta is the rotation angle vector of each wheel;m is the torque vector of each wheel, B R The reciprocal of the rotational inertia of the wheel;
from the desired wheel speed omega of the ith wheel i，d Obtaining the expected wheel rotation speed omega of each wheel d Desired wheel rotational speed ω for each wheel d From actual wheel speed omega ist Difference e of ω ＝ω d -ω ist And (3) adopting P control to obtain an actual wheel torque control equation:
Figure GDA0004159696090000065
wherein f R () As a function of wheel direction, w R ＝C R e ω ，C R As a matrix of proportionality coefficients, delta d For each wheel the expected angle vector, B R Which is the reciprocal of the moment of inertia of the wheel.
Further, in the above method, the longitudinal and lateral driving forces F are expected based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
the desired wheel slip ratio is formulated as follows:
Figure GDA0004159696090000066
wherein the maximum expected driving force F max，i，d The method comprises the following steps:
Figure GDA0004159696090000071
wherein mu is i For road adhesion coefficient B i ，C i Is the coefficient of the magic formula of the tire,
Figure GDA0004159696090000072
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Represents the vertical load of a standard tire, F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
the wheel rotation angle can be obtained according to the formula of the vehicle speed and the expected wheel slip rate
Figure GDA0004159696090000073
Is calculated according to the formula:
Figure GDA0004159696090000074
wherein S is xi，d Representation, S yi，d Representation, v xi，d Indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
adding an inertia link to the rotation angle, so that the expected rotation angle delta of the ith wheel i，d The method comprises the following steps:
Figure GDA0004159696090000075
wherein p represents a transfer function, T δ Indicating the wheel rotation angle time constant,
Figure GDA0004159696090000076
representation->
Figure GDA0004159696090000077
Is a laplace transform of (a);
the controller uses the actual rotation angle delta of the wheel ist Desired steering angle delta for each wheel formulated by wheel dynamics controller d Difference e of δ ＝δ d -δ ist The input is the actual rotation angle delta of the wheel ist And based on the formula (1), the following expression is obtained:
Figure GDA0004159696090000078
wherein delta i，ist (p) represents the actual rotation angle of the ith wheel, C δ，i Taking 500s-1 as a proportionality coefficient; t (T) δ Taking 0.025s as a time constant; p is a transfer function;
based on formula (2), the expected wheel angle delta of the ith wheel is calculated i，d 。
According to another aspect of the present invention, there is also provided a torque distribution apparatus for a four-wheel drive-by-wire and steering vehicle, wherein the apparatus includes:
first means for, based on the actual running state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d The method comprises the steps of carrying out a first treatment on the surface of the Second means for generating a generalized driving force u according to the desired driving force d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d ；
Third means for estimating the longitudinal and lateral driving forces F based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d ；
Fourth means for based on the desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
According to another aspect of the present invention there is also provided a computer readable medium having stored thereon computer readable instructions executable by a processor to implement the method of any one of the above.
According to another aspect of the present invention there is also provided an apparatus for information processing at a network device, the apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to perform the method of any of the preceding claims.
Compared with the prior art, the invention is based on the actual running state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle cdelta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d The method comprises the steps of carrying out a first treatment on the surface of the According to the expected generalized driving force u d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d The method comprises the steps of carrying out a first treatment on the surface of the Based on the desired longitudinal and lateral driving forces F of the wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d The method comprises the steps of carrying out a first treatment on the surface of the Based on desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d The invention can realize that the vehicle runs in the optimal posture, ensure the stability of the vehicle and can be combined with an automatic driving system.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:
fig. 1 shows a schematic diagram of a torque distribution method of a four-wheel drive-by-wire and steering vehicle according to an embodiment of the present invention.
The same or similar reference numbers in the drawings refer to the same or similar parts.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
In one typical configuration of the present application, the terminal, the device of the service network, and the trusted party each include one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of computer-readable media.
Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. Computer readable media, as defined herein, does not include non-transitory computer readable media (transmission media), such as modulated data signals and carrier waves.
The four-wheel drive-by-wire and steering-by-wire automobile is provided with four independent controllable driving and steering units, the automobile is driven by directly outputting torque to four wheels, compared with the traditional automobile, the automobile has great advantage in the aspect of improving the torque response of the whole automobile, and the high-speed drive-by-wire system is also the driving mode most suitable for automatic driving.
Four-wheel drive-by-wire and steering provide a great degree of freedom for vehicle stability control, but also add complexity to the control system. At present, the overdrive system mainly aims at the centroid slip angle or the centroid slip angle speed to perform optimal control distribution. The centroid slip angle is often difficult to measure or estimate and unaccounted for motor failure modes easily result in failure of the control algorithm when the motor fails.
Thus, as shown in fig. 1, the present invention provides a torque distribution method of a four-wheel drive-by-wire and steering vehicle, the method comprising:
step S1, based on the actual running state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d 。
Specifically, firstly, the vehicle body horizontal dynamics controller can be based on the actual running state x of the vehicle ist (including X longitudinal speed, Y lateral speed, and yaw rate) and an accelerator pedal opening ratio alpha entered by the driver or an autopilot controller G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d ；
Step S2, according to the expected generalized driving force u d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d 。
Here, the driving force distributor derives the desired generalized driving force u according to the vehicle body horizontal dynamics controller d And the desired bearable tire driving force F of the wheel dynamics controller max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d ；
Step S3, based on the expected longitudinal and lateral driving forces F of each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d The method comprises the steps of carrying out a first treatment on the surface of the Here, the wheel dynamics controller is based on the desired longitudinal and lateral driving forces F of the individual wheels xy，d Actual wheel speed ω fed back by the vehicle ist And the actual wheel angle delta ist Desired vertical load F by body vertical dynamics controller z，d Calculation ofDesired wheel torque M d And the desired wheel rotation angle delta d 。
The invention can be proportionally controlled to optimize the desired wheel torque M d And the desired wheel rotation angle delta d 。
Step S4, based on the desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
Specifically, a hub motor can be installed in the wheel, and the hub motor is communicated with a driving system to realize the driving of the vehicle; the hub motor is communicated with a steering system to realize steering of the vehicle. The invention can realize that the vehicle runs in the optimal posture, ensure the stability of the vehicle, and can be combined with an automatic driving system.
Optionally, in one embodiment of the torque distribution method of the four-wheel drive-by-wire and steering vehicle of the present invention, step S3 is based on the desired longitudinal and lateral driving forces F of each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Before, still include:
according to the actual vertical motion state y fed back by the vehicle v，ist Calculating the desired vertical load F z，d 。
Specifically, the vehicle body vertical dynamics controller can control the vehicle body vertical dynamics controller according to the actual vertical motion state y fed back by the vehicle ist The method comprises the steps of calculating expected vertical load by means of vertical runout displacement of the vehicle body, pitch angle of the vehicle body and roll angle of the vehicle body. The invention optimizes the vertical motion with PID control.
Preferably, in one embodiment of the torque distribution method for four-wheel drive-by-wire and steering vehicle of the present invention, the actual vertical movement state y fed back by the vehicle is based on v，ist Calculating the desired vertical load F z，d Comprising:
1) Besides the spring and damping effect on the car body, the active suspension also generates an additional active force, and the vertical dynamics control is to control the magnitude of the active force.
The following vertical dynamics equation can be obtained in the time domain:
Figure GDA0004159696090000111
wherein G is v1 (p)、G v2 (p)、G v3 (p) is a transfer function with the vertical displacement of the mass center of the vehicle body, the roll angle of the vehicle body and the pitch angle of the vehicle body as output, w v (p) is the suspension active force transfer function, z v (p) is a vertical kinetic transfer function caused by external disturbance forces;
G vi and (p) is a minimum phase system consisting of vehicle parameters such as vehicle mass, suspension rigidity, damping, wheelbase and the like, and in order to improve the steady-state accuracy of control, the following PID controllers are adopted:
Figure GDA0004159696090000112
wherein T is N To adjust the time; τ D Is a low-pass time constant.
2) Vertical load formulation
In the running process of the vehicle, the expected vertical displacement, the expected roll angle and the expected pitch angle of the vehicle body are all 0, so the expected vertical load F z，d The following are provided:
F z，d ＝f v (0，ΔF z )＝V + w v +F z，F0 ，
f v () Represents the vertical direction function, ΔF z For the main force vector of the suspension, F z，F0 Is static vertical load vector, w v Is the stress vector of the vertical plane of the mass center of the vehicle body, V + Is the generalized inverse of the vertical control efficiency matrix V.
From y v，ist Can obtain the stress vector w of the vertical plane of the mass center of the vehicle body v ，y v，ist Is y v (p)，y v (p) by w in body motion control v (p) p, p being the transfer function.
Specifically, the vertical efficiency matrix V is as follows:
Figure GDA0004159696090000121
here, the vehicle body vertical dynamics includes two parts, a vehicle body motion control and a vertical load control.
Preferably, in an embodiment of the torque distribution method of the four-wheel drive-by-wire and steering vehicle of the present invention, the desired generalized driving force u required for running the vehicle d Comprising: desired longitudinal driving force
Figure GDA0004159696090000122
Desired lateral driving force +.>
Figure GDA0004159696090000123
And a desired yaw moment M zd 。
Here, the vehicle body horizontal dynamics control includes a desired longitudinal driving force
Figure GDA0004159696090000124
Desired lateral driving force +.>
Figure GDA0004159696090000125
And a desired yaw moment M zd Three parts.
Further, the desired longitudinal driving force
Figure GDA0004159696090000126
The determination is based on the following formula: />
Figure GDA0004159696090000127
Wherein F is xD For the longitudinal driving component, F xB Alpha, being the longitudinal braking component B C for brake pedal opening ratio s Approximating the parameters for the symbols;
F xD ＝f D (α G )·F xDmax ；
wherein F is xDmax For maximum driving force achievable by the vehicle, alpha G Is the accelerator pedal opening ratio.
Further, the desired lateral driving force
Figure GDA0004159696090000128
According to the following formula:
Figure GDA0004159696090000129
wherein m is the mass of the whole vehicle, l is the wheelbase of the vehicle, EG is the vehicle stability factor, delta SW For steering wheel angle, v x Is the vehicle longitudinal speed.
Further, the desired yaw moment M zd According to the following formula:
Figure GDA0004159696090000131
wherein a is 1 、a 0 Is the dynamic characteristic parameter of the centroid slip angle,
Figure GDA0004159696090000132
for the desired longitudinal speed>
Figure GDA0004159696090000133
For the desired transverse speed>
Figure GDA0004159696090000134
Desired yaw angle for vehicle, < >>
Figure GDA0004159696090000135
Ideal vehicle operating state x for desired lateral driving force d Comprising the following steps: vehicle desired longitudinal speed>
Figure GDA0004159696090000136
Vehicle desired lateral speed>
Figure GDA0004159696090000137
And the desired yaw angle of the vehicle->
Figure GDA0004159696090000138
Specifically, the above formula can be obtained by using the Byrnes-Isidori standard after ignoring external disturbance forces and moments.
Optionally, in one embodiment of the torque distribution method for four-wheel drive-by-wire and steering vehicle of the present invention, step S2, the driving force u is generalized according to the expected driving force u d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d Comprising:
step S21, the driving force distribution is first required to satisfy the requirement that the vehicle travel in accordance with the driver' S desired trajectory, that is, to minimize the desired generalized force u d And the actual generalized force GF xy，d The deviation between them, the first objective can be expressed by the following mathematical formula:
Figure GDA0004159696090000139
wherein W is 1 The third-order diagonal matrix is used for describing the weight of the influence of the longitudinal force, the lateral force and the yaw moment on the first target;F xy to achieve the lower limit value of the tire driving force,
Figure GDA00041596960900001310
an upper limit value for the tire driving force that can be achieved; g is a control efficiency matrix and consists of vehicle parameters such as the distance from the left and right wheels to the longitudinal center line of the vehicle, the distance from the front and rear axles to the mass center of the vehicle and the like.
The control efficiency matrix G may be as follows:
Figure GDA0004159696090000141
/>
wherein s is l 、s r For the distance between the left wheel and the right wheel and the central line of the vehicle, l v 、l h Distance from the front and rear axles to the center of mass of the vehicle;
in addition to the track following, the step S22 may further implement a second target for reducing the maximum utilization rate of the tire by using the redundancy control amount, so as to ensure the safety of the vehicle, where an objective function and constraint conditions of the second target are as follows:
min max(η i )
s.t.0≤η i ≤1 i＝1...4，
wherein eta i The tire utilization is determined by the actual driving force F of the tire i And a maximum expected driving force F max，i，d I is the wheel number.
The maximum utilization rate of the tire can be simplified as follows:
Figure GDA0004159696090000142
step S23, according to the first and second objectives, an optimized objective function may be obtained:
Figure GDA0004159696090000143
Figure GDA0004159696090000144
f Fi (F xy )≤η max F max，id ， i＝1...4，
0≤η max ≤1
selecting new optimization variable x= [ eta ] max F xy ] T The objective function and constraints are further rewritten as:
Figure GDA0004159696090000151
Figure GDA0004159696090000152
f Fi，e (x)-c T xF max，id ≤0， i＝1...4，
the method meets the following conditions:
Figure GDA0004159696090000153
step S24, considering that the motor fails to cause the wheel to lose control, if the algorithm cannot adjust in time, the unexpected yaw rate of the vehicle can be caused, and the running stability of the vehicle is affected, so the invention introduces a motor failure factor epsilon into the optimized objective function i The optimization objective function is as follows:
Figure GDA0004159696090000154
Figure GDA0004159696090000155
f Fi，e (x)-c T xε i F max，id ≤0， i＝1...4，
wherein the optimal solution of x is the expected longitudinal and lateral driving force F of each wheel xy，d 。
Specifically, for different failure modes, the motor failure factor ε i Can be varied according to the following table:
failure mode Results
Normal mode All motor failure factors epsilon i Device 1
Failure of a single motor Failure factor epsilon of failure motor i Put 0, the rest are 1
Failure of same-side motor All motor failure factors epsilon i Put 0
Failure of coaxial motor Failure factor epsilon of failure motor i Put 0, the rest are 1
Failure of diagonal motor Failure factor epsilon of failure motor i Put 0, the rest are 1
Failure of three motors All motor failure factors epsilon i Put 0
Failure of four motors All motor failure factors epsilon i Put 0
。
In this embodiment, in order to ensure that the expected path (the first target) of the vehicle and the minimization of the maximum road surface attachment coefficient utilization (the second target) are double targets, the driving force distribution is simplified into a convex optimization problem with constraint conditions based on the optimal control theory to solve the problem in combination with the failure condition of the motor. For the convex optimization problem, the local optimal solution is the global optimal solution, so that the target optimization can be ensured.
The vehicle is driven safely and efficiently by taking the stability of the vehicle and the motor fault as dual targets.
Preferably, in one embodiment of the torque distribution method for four-wheel drive-by-wire and steering vehicle of the present invention, step S3 is based on the expected longitudinal and lateral driving forces F of each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
in step S311, the desired wheel slip ratio formula is as follows:
Figure GDA0004159696090000161
wherein the maximum expected driving force F maxi，d The method comprises the following steps:
Figure GDA0004159696090000171
wherein mu is i For road adhesion coefficient, B i ，C i Is the coefficient of the magic formula of the tire,
Figure GDA0004159696090000172
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Represents the vertical load of a standard tire, F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
obtaining the wheel rotation speed according to the formula of the vehicle speed and the expected wheel slip rate
Figure GDA0004159696090000173
Is calculated according to the formula:
Figure GDA0004159696090000174
wherein S is xi，d Indicating the desired longitudinal slip ratio S yi，d Indicating the desired lateral slip rate, r wheel Representing the radius of the wheel, v xi，d Indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
in order to ensure the continuity of the rotation speed and the rotation angle of the wheel, an inertia link is added to the rotation speed to obtain the expected wheel rotation speed omega of the ith wheel i，d The method comprises the following steps:
Figure GDA0004159696090000175
wherein p represents a transfer function, T ω Indicating the time constant of the rotational speed of the wheel,
Figure GDA0004159696090000176
representation->
Figure GDA0004159696090000177
Is a laplace transform of (a);
step S312, wheel rotation speed control:
from the tire dynamics model, it is obtained:
Figure GDA0004159696090000178
wherein f R () As a wheel direction function, ω is a rotational angular velocity vector of each wheel; delta is the rotation angle vector of each wheel; m is the torque vector of each wheel, B R The reciprocal of the rotational inertia of the wheel;
from the desired wheel speed omega of the ith wheel i，d Obtaining the expected wheel rotation speed omega of each wheel d Desired wheel speed for each wheel:
Figure GDA0004159696090000181
wherein f R () As a function of wheel direction, w R ＝C R e ω ，C R As a matrix of proportionality coefficients, delta d For each wheel the expected angle vector, B R Which is the reciprocal of the moment of inertia of the wheel.
Preferably, in one embodiment of the torque distribution method for four-wheel drive-by-wire and steering vehicle of the present invention, step S3 is based on the expected longitudinal and lateral driving forces F of each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
in step S321, the desired wheel slip ratio formula is as follows:
Figure GDA0004159696090000182
wherein the maximum expected driving force F max，i，d The method comprises the following steps:
Figure GDA0004159696090000183
wherein mu is i For road adhesion coefficient B i ，C i Is the coefficient of the magic formula of the tire,
Figure GDA0004159696090000184
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Represents the vertical load of a standard tire, F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
the wheel rotation angle can be obtained according to the formula of the vehicle speed and the expected wheel slip rate
Figure GDA0004159696090000191
Is calculated according to the formula:
Figure GDA0004159696090000192
wherein S is xi，d Representation, S yi，d Representation, v xi，d Indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
in order to ensure the continuity of the rotation speed and the rotation angle of the wheel, an inertia link is added to the rotation angle, so the expected rotation angle delta of the ith wheel i，d The method comprises the following steps:
Figure GDA0004159696090000193
wherein p represents a transfer function, T δ Indicating the wheel rotation angle time constant,
Figure GDA0004159696090000194
representation->
Figure GDA0004159696090000195
Is a laplace transform of (a); step S322, the controller uses the actual wheel rotation angle delta ist Desired steering angle delta for each wheel formulated by wheel dynamics controller d Difference e of δ ＝δ d -δ ist The input is the actual rotation angle delta of the wheel ist And based on the formula (1), the following expression is obtained:
Figure GDA0004159696090000196
wherein delta i，ist (p) represents the actual rotation angle of the ith wheel, C δ，i Taking 500s-1 as a proportionality coefficient; t (T) δ Taking 0.025s as a time constant; p in() is the transfer function;
based on formula (2), the expected wheel angle delta of the ith wheel is calculated i，d 。
According to another aspect of the present invention, there is also provided a torque distribution apparatus for a four-wheel drive-by-wire and steering vehicle, wherein the apparatus includes:
first means for, based on the actual running state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d ；
Second means for generating a generalized driving force u according to the desired driving force d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d ；
Third means for estimating the longitudinal and lateral driving forces F based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d ；
Fourth means for based on the desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
According to another aspect of the present invention there is also provided a computer readable medium having stored thereon computer readable instructions executable by a processor to implement the method of any one of the above.
According to another aspect of the present invention there is also provided an apparatus for information processing at a network device, the apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to perform the method of any of the preceding claims.
Details of each device embodiment of the present invention may be specifically referred to corresponding portions of each method embodiment, and will not be described herein.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.
It should be noted that the present invention may be implemented in software and/or a combination of software and hardware, e.g., using Application Specific Integrated Circuits (ASIC), a general purpose computer or any other similar hardware device. In one embodiment, the software program of the present invention may be executed by a processor to perform the steps or functions described above. Likewise, the software programs of the present invention (including associated data structures) may be stored on a computer readable recording medium, such as RAM memory, magnetic or optical drive or diskette and the like. In addition, some steps or functions of the present invention may be implemented in hardware, for example, as circuitry that cooperates with the processor to perform various steps or functions.
Furthermore, portions of the present invention may be implemented as a computer program product, such as computer program instructions, which when executed by a computer, may invoke or provide methods and/or techniques in accordance with the present invention by way of operation of the computer. Program instructions for invoking the inventive methods may be stored in fixed or removable recording media and/or transmitted via a data stream in a broadcast or other signal bearing medium and/or stored within a working memory of a computer device operating according to the program instructions. An embodiment according to the invention comprises an apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to operate a method and/or a solution according to the embodiments of the invention as described above.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. A plurality of units or means recited in the apparatus claims can also be implemented by means of one unit or means in software or hardware. The terms first, second, etc. are used to denote a name, but not any particular order.

Claims (11)

1. A torque distribution method for a four-wheel drive-by-wire and steering vehicle, wherein the method comprises:
based on the actual operating state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d Wherein a desired generalized driving force u required for running of the vehicle d Comprising: desired longitudinal driving force
Figure FDA0004159696080000011
Desired lateral driving force +.>
Figure FDA0004159696080000012
And a desired yaw moment M zd ；
According to the expected generalized driving force u d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d Wherein the desired longitudinal driving force
Figure FDA0004159696080000013
The determination is based on the following formula:
Figure FDA0004159696080000014
wherein F is xD For the longitudinal driving component, F xB Alpha, being the longitudinal braking component B C for brake pedal opening ratio s The symbol approximation parameters;
F xD ＝f D (α G )·F xDmax ；
wherein F is xDmax For maximum driving force achievable by the vehicle, alpha G Is the accelerator pedal opening ratio;
based on the desired longitudinal and lateral driving forces F of the wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d ；
Based on desired wheel torque M d : controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
2. The method of claim 1, wherein the longitudinal and lateral driving forces F are expected based on each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Before, still include:
according to the actual vertical motion state y fed back by the vehicle v，ist Calculating the desired vertical load F z，d 。
3. The method according to claim 2, wherein the actual vertical movement state y fed back by the vehicle v，ist Calculating the desired vertical load F z，d Comprising:
the following vertical dynamics equation is obtained in the time domain:
Figure FDA0004159696080000015
wherein G is v1 (p)、G v2 (p)、G v3 (p) is a transfer function with the vertical displacement of the mass center of the vehicle body, the roll angle of the vehicle body and the pitch angle of the vehicle body as output, w v (p) is the suspension active force transfer function, z v (p) is a vertical kinetic transfer function caused by external disturbance forces;
G vi (p) is a minimum phase system consisting of vehicle mass, suspension stiffness and damping, wheelbase, in order to improve the steady-state accuracy of the control, the following PID controllers are employed:
Figure FDA0004159696080000021
wherein T is N To adjust the time; τ D Is a low-pass time constant;
in the running process of the vehicle, the expected vertical displacement, the expected roll angle and the expected pitch angle of the vehicle body are all 0, so the expected vertical load F z，d The following are provided:
F z，d ＝f v (0，ΔF z )＝V + w v +F z，F0 ，
wherein f v () Represents the vertical direction function, ΔF z For the main force vector of the suspension, F z，F0 Is static vertical load vector, w v Is the stress vector of the vertical plane of the mass center of the vehicle body, V + Is the generalized inverse of the vertical control efficiency matrix V; from y v，ist Obtaining a stress vector w of a vertical plane of the mass center of the vehicle body v ，y v，ist Is y v (p)，y v (p) by w in body motion control v (p) p, p being the transfer function.
4. According to claim 1The method wherein the desired lateral driving force
Figure FDA0004159696080000022
According to the following formula:
Figure FDA0004159696080000023
wherein m is the mass of the whole vehicle, and l: EG is the vehicle stability factor, delta, for the vehicle wheelbase SW For steering wheel angle, v x Is the vehicle longitudinal speed.
5. The method of claim 1, wherein the desired yaw moment M zd According to the following formula:
Figure FDA0004159696080000024
wherein a is 1 、a 0 Is the dynamic characteristic parameter of the centroid slip angle,
Figure FDA0004159696080000025
for the desired longitudinal speed>
Figure FDA0004159696080000026
For the desired transverse speed>
Figure FDA0004159696080000031
Desired yaw angle for vehicle, < >>
Figure FDA0004159696080000032
Ideal vehicle operating state x for desired lateral driving force d Comprising the following steps: desired longitudinal speed of the vehicle
Figure FDA0004159696080000033
Period of the vehicleLooking at transverse speed +.>
Figure FDA0004159696080000034
And the desired yaw angle of the vehicle->
Figure FDA0004159696080000035
6. The method according to claim 1, wherein the generalized driving force u is based on a desired driving force d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d Comprising:
setting a first target, wherein the first target is expressed by the following mathematical formula:
Figure FDA0004159696080000036
wherein W is 1 The third-order diagonal matrix is used for describing the weight of the influence of the longitudinal force, the lateral force and the yaw moment on the first target;F xv to achieve the lower limit value of the tire driving force,
Figure FDA0004159696080000037
an upper limit value for the tire driving force that can be achieved; g is a control efficiency matrix;
setting a second target, wherein the target function and constraint conditions of the second target are as follows:
min max(η i )
s.t.0≤η i ≤1 i＝1...4，
wherein eta i The tire utilization is determined by the actual driving force F of the tire i And a maximum expected driving force F max，i，d I is the wheel number;
the maximum utilization rate of the tire is simplified as follows:
Figure FDA0004159696080000038
according to the first and second objectives, an optimized objective function is obtained:
Figure FDA0004159696080000041
Figure FDA0004159696080000042
f Fi (F xy )≤η max F max，id ，i＝1...4，
0≤η max ≤1
selecting new optimization variable x= [ eta ] max F xy ] T The objective function and constraints are further rewritten as:
Figure FDA0004159696080000043
Figure FDA0004159696080000044
Figure FDA0004159696080000045
the method meets the following conditions:
Figure FDA0004159696080000046
introducing a motor failure factor epsilon into an optimized objective function i The optimization objective function is as follows:
Figure FDA0004159696080000047
Figure FDA0004159696080000048
Figure FDA0004159696080000049
wherein the optimal solution of x is the expected longitudinal and lateral driving force F of each wheel xy，d 。
7. The method of claim 1, wherein the longitudinal and lateral driving forces F are expected based on each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
the desired wheel slip ratio is formulated as follows:
Figure FDA0004159696080000051
wherein the maximum expected driving force F max，i，d The method comprises the following steps:
Figure FDA0004159696080000052
wherein mu is i For road adhesion coefficient, B i ，C i Is the coefficient of the magic formula of the tire,
Figure FDA0004159696080000059
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Representing normal tire vertical load，F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
obtaining the wheel rotation speed according to the formula of the vehicle speed and the expected wheel slip rate
Figure FDA0004159696080000053
Is calculated according to the formula:
Figure FDA0004159696080000054
wherein s is xi，d Indicating the desired longitudinal slip ratio S yi，d Indicating the desired lateral slip rate, r wheel Representing the radius of the wheel, v xi，d : indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
adding an inertia link to the rotation speed to obtain the expected wheel rotation speed omega of the ith wheel i，d The method comprises the following steps:
Figure FDA0004159696080000055
wherein p represents a transfer function, T ω Indicating the time constant of the rotational speed of the wheel,
Figure FDA0004159696080000056
representation->
Figure FDA0004159696080000057
Is a laplace transform of (a);
from the tire dynamics model, it is obtained:
Figure FDA0004159696080000058
wherein f R () As a function of wheel direction, ω being the respective wheelRotating the angular velocity vector; delta is the rotation angle vector of each wheel; m is the torque vector of each wheel, B R The reciprocal of the rotational inertia of the wheel;
from the desired wheel speed omega of the ith wheel i，d Obtaining the expected wheel rotation speed omega of each wheel d Desired wheel rotational speed ω for each wheel d From actual wheel speed omega ist Difference e of ω ＝ω d -ω ist And (3) adopting P control to obtain an actual wheel torque control equation:
Figure FDA0004159696080000061
wherein f R () As a function of wheel direction, w R ＝C R e ω ，C R As a matrix of proportionality coefficients, delta d For each wheel the expected angle vector, B R Which is the reciprocal of the moment of inertia of the wheel.
8. The method of claim 1, wherein the longitudinal and lateral driving forces F are expected based on each wheel xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d Comprising:
the desired wheel slip ratio is formulated as follows:
Figure FDA0004159696080000062
wherein the maximum expected driving force F max，i，d The method comprises the following steps:
Figure FDA0004159696080000063
wherein mu is i For road adhesion coefficient B i ，C i Is the coefficient of the magic formula of the tire,
Figure FDA0004159696080000064
the tire is decremented by a factor, i is the wheel number, F zi，d For the desired vertical load of the ith wheel, F z0 Represents the vertical load of a standard tire, F xi，d Indicating the desired longitudinal driving force of the ith wheel, F yi，d Indicating the desired lateral driving force of the ith wheel;
the wheel rotation angle can be obtained according to the formula of the vehicle speed and the expected wheel slip rate
Figure FDA0004159696080000065
Is calculated according to the formula:
Figure FDA0004159696080000071
wherein S is xi，d Indicating the desired longitudinal slip ratio S yi，d Indicating the desired lateral slip ratio, v xi，d Indicating the expected longitudinal vehicle speed, v, of the ith wheel yi，d Representing a desired lateral vehicle speed of the ith wheel;
adding an inertia link to the rotation angle, so that the expected rotation angle delta of the ith wheel i，d The method comprises the following steps:
Figure FDA0004159696080000072
wherein p represents a transfer function, T δ Indicating the wheel rotation angle time constant,
Figure FDA0004159696080000073
representation->
Figure FDA0004159696080000074
Is a laplace transform of (a);
the controller uses the actual rotation angle delta of the wheel ist And wheels of vehicleThe difference e between the desired rotational angles of the wheels established by the dynamics controller δ ＝δ d -δ ist The input is the actual rotation angle delta of the wheel ist And based on the formula (1), the following expression is obtained:
Figure FDA0004159696080000075
wherein delta i，ist (p) represents the actual rotation angle of the ith wheel, C δ，i Taking 500s as a proportionality coefficient -1 ；T δ Taking 0.025s as a time constant; p is a transfer function;
based on formula (2), the expected wheel angle delta of the ith wheel is calculated i，d 。
9. A torque distribution apparatus for a four-wheel drive-by-wire and steering vehicle, wherein the apparatus comprises:
first means for, based on the actual running state x of the vehicle ist And a preset accelerator pedal opening ratio alpha G Opening ratio alpha of brake pedal B Steering wheel angle delta SW Determining a desired generalized driving force u required for running of a vehicle d And ideal vehicle operating state x d Wherein a desired generalized driving force u required for running of the vehicle d Comprising: desired longitudinal driving force
Figure FDA0004159696080000076
Desired lateral driving force +.>
Figure FDA0004159696080000077
And a desired yaw moment M zd ；
Second means for generating a generalized driving force u according to the desired driving force d And expects to bear the tire driving force F max，d Optimally distributing the desired longitudinal and lateral driving forces F of the wheels xy，d Wherein the desired longitudinal driving force
Figure FDA0004159696080000078
The determination is based on the following formula:
Figure FDA0004159696080000081
wherein F is xD For the longitudinal driving component, F xB Alpha, being the longitudinal braking component B C for brake pedal opening ratio s Approximating the parameters for the symbols;
F xD ＝f D (α G )·F xDmax ；
wherein F is xDmax For maximum driving force achievable by the vehicle, alpha G Is the accelerator pedal opening ratio;
third means for estimating the longitudinal and lateral driving forces F based on the respective wheels xy，d Actual wheel speed ω ist And the actual wheel angle delta ist Ideal running state x of vehicle d And a desired vertical load F z，d Calculating the desired wheel torque M d And the desired wheel rotation angle delta d ；
Fourth means for based on the desired wheel torque M d Controlling a drive system of a vehicle based on a desired wheel angle delta d Controlling a steering system of the vehicle.
10. A computer readable medium having stored thereon computer readable instructions executable by a processor to implement the method of any one of claims 1 to 8.
11. An apparatus for information processing at a network device, the apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein the computer program instructions, when executed by the processor, trigger the apparatus to perform the method of any one of claims 1 to 8.
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