CN120792776A

CN120792776A - Control method and system for vehicle curve driving and vehicle

Info

Publication number: CN120792776A
Application number: CN202511097067.6A
Authority: CN
Inventors: 张平平; 孙国照
Original assignee: WUHU BETHEL ELECTRONIC CONTROL SYSTEMS CO Ltd
Current assignee: WUHU BETHEL ELECTRONIC CONTROL SYSTEMS CO Ltd
Filing date: 2025-08-06
Publication date: 2025-10-17

Abstract

The invention discloses a control method and a system for vehicle curve driving, and a vehicle, wherein the method comprises the steps of calculating the maximum longitudinal force of the wheels at the inner side of the curve in real time when the vehicle is driven at the curve, and controlling the braking force of the inner wheels according to the maximum longitudinal force and the braking or driving state of the current vehicle so as to ensure the running stability of the vehicle in a curve. The invention has the advantages that through innovative feedforward control architecture and high-precision dynamics modeling, core problems of response lag, model precision deficiency and the like in traditional curve stability control are effectively solved, and the safety and the operability of the vehicle under the extreme turning working condition are obviously improved.

Description

Control method and system for vehicle curve driving and vehicle

Technical Field

The invention relates to the technical field of automobile safety braking control, in particular to a control method and system for vehicle curve driving and a vehicle.

Background

When the vehicle turns, the load transfer is caused by the centrifugal force, the vertical load of the inner side wheel is obviously reduced, and the longitudinal adhesive force of the inner side wheel is drastically reduced. In this case, if the driver applies driving force or braking operation, the vehicle is liable to slip or lock up due to the longitudinal force of the inner wheel exceeding the adhesion limit, and further, the vehicle power loss or unexpected yaw may occur.

The traditional vehicle stability control system mostly adopts a feedback closed-loop control strategy, and the braking force adjustment is triggered after the wheel slip or locking is detected by a wheel speed sensor. However, such methods have significant delays, rely on real-time feedback signals to correct the control amount, and cannot suppress potential slip or locking tendency in advance. When the system detects that the wheel speed is abnormal, the tire enters an obvious sliding or locking state, and then a large control intervention is needed to stabilize the wheel, the whole control is rough, and due to the delay of the intervention, the running safety risk is also generated due to the sliding or locking.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a control method and system for vehicle curve driving and a vehicle, and aims to solve the core problems of response lag, insufficient model precision and the like in the traditional curve stability control, and the safety and the operability of the vehicle under the limit turning working condition are obviously improved.

In order to achieve the aim, the technical scheme adopted by the invention is that the control method for the curve running of the vehicle comprises the steps of calculating the maximum longitudinal force of the inner side wheels of the curve in real time when the vehicle runs on the curve, and controlling the braking force of the inner side wheels according to the maximum longitudinal force and the braking or driving state of the current vehicle so as to ensure the stability of the curve running of the vehicle.

When the vehicle wheels in the curve driving are in a driving state, the actual driving force of the inner wheels is acquired and calculated in real time, and the braking force of the inner wheels is controlled based on the actual driving force of the inner vehicle and the maximum longitudinal force.

When the actual driving force of the inner wheel is greater than the maximum longitudinal force, a braking force is applied to the inner wheel.

When the vehicle wheels running on the curve are in a braking state, the actual braking force of the inner wheels is acquired and calculated in real time, and the braking force of the inner wheels is controlled based on the actual braking force of the inner vehicle and the maximum longitudinal force.

When the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking force is limited.

The method for calculating the maximum longitudinal force of the wheel at the inner side of the curve comprises the following steps:

(1) Establishing a whole vehicle model, and calculating the slip angle and load of the inner side wheels of the vehicle in real time;

(2) After the slip angle and load of the inside wheel are calculated, the maximum longitudinal adhesion force of the inside wheel is determined according to the tire adhesion elliptic curve.

When the actual driving force of the inner wheel is greater than the maximum longitudinal force, the moment for applying the braking force to the inner wheel is t_brk=max (Fx-Fx, max, 0) R, where R is the tire radius, fx is the real-time driving force, F _x,max is the maximum longitudinal force of the inner wheel, and the max function is the maximum function.

When the actual braking force of the inboard wheel is greater than the maximum longitudinal force, the limiting wheel braking torque is less than or equal to μF _z,in R, where R is the wheel radius, F _z,in is the inboard wheel vertical load, and the μroad friction coefficient.

A control system for driving a vehicle at a curve comprises an acquisition and calculation module, a control module, a driving module and a braking module;

the acquisition and calculation module is used for calculating the maximum longitudinal force of the wheel at the inner side of the curve in real time when the vehicle runs on the curve;

The control module calculates a driving control signal or a braking control signal for the inner vehicle according to the calculated maximum longitudinal force and the real-time braking force of the current vehicle in a braking state or the driving force of the current vehicle in a driving state, and the driving module and the braking module control the braking force of the inner vehicle based on the driving control signal or the driving control signal.

A vehicle comprising said method for controlling the curve travel of the vehicle or said system for controlling the curve travel of the vehicle.

The invention has the advantages that through innovative feedforward control architecture and high-precision dynamics modeling, core problems of response lag, model precision deficiency and the like in traditional curve stability control are effectively solved, and the safety and the operability of the vehicle under the extreme turning working condition are obviously improved. Compared with the prior art, the control method has the advantages that the control intervention delay is shorter, the safety control requirement during over-bending can be met, the phenomenon that the wheels on the inner side of the vehicle slide or lock under the over-bending condition is effectively avoided, and the safety of over-bending operation is improved.

Drawings

The contents of the drawings and the marks in the drawings of the present specification are briefly described as follows:

FIG. 1 is a flow chart of a control method of the present invention;

FIG. 2 is a tire characteristic curve;

Fig. 3 is a schematic diagram of adhesion calculation of an adhesion elliptic curve.

Detailed Description

The following detailed description of the invention refers to the accompanying drawings, which illustrate preferred embodiments of the invention in further detail.

As shown in fig. 1, a control method for driving a curve of a vehicle is a feedforward control method for preventing wheels on the inner side of the curve from slipping or locking, a slip angle and a load of the inner side wheels during turning are calculated through a whole vehicle model, and the maximum longitudinal adhesive force of the inner side wheels is obtained according to an attached elliptic curve. When the wheels are in a driving state, if the driving force of the inner side wheels is larger than the maximum longitudinal adhesive force, braking torque is applied to the inner side wheels, so that the inner side wheels are prevented from slipping, the torsion is prevented from being reduced during turning, and the sufficient power is ensured during the over-turning of the vehicle. When the wheels are in a braking state, if the braking moment of the inner side wheels is larger than or equal to the locking moment of the wheels, the braking force of the inner side wheels is limited by pressure maintaining, so that the inner side wheels are prevented from generating larger slippage, and the stability of the whole vehicle is ensured.

The method specifically comprises the steps of calculating the maximum longitudinal force of the wheels at the inner side of the curve in real time when the vehicle runs on the curve, and controlling the braking force of the wheels at the inner side according to the maximum longitudinal force and the braking or driving state of the current vehicle so as to ensure the running stability of the vehicle at the curve.

When the vehicle wheels in the curve driving are in a driving state, the actual driving force of the inner wheels is acquired and calculated in real time, and the braking force of the inner wheels is controlled based on the actual driving force of the inner vehicle and the maximum longitudinal force. When the actual driving force of the inner wheel is greater than the maximum longitudinal force, a braking force is applied to the inner wheel. When the actual driving force of the inner wheel is greater than the maximum longitudinal force, the moment for applying the braking force to the inner wheel is t_brk=max (Fx-Fx, max, 0) R, where R is the tire radius, fx is the real-time driving force, F _x,max is the maximum longitudinal force of the inner wheel, and the max function is the maximum function.

When the vehicle wheels running on the curve are in a braking state, the actual braking force of the inner wheels is acquired and calculated in real time, and the braking force of the inner wheels is controlled based on the actual braking force of the inner vehicle and the maximum longitudinal force. When the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking force is limited. When the actual braking force of the inboard wheel is greater than the maximum longitudinal force, the limiting wheel braking torque is less than or equal to μF _z,in R, where R is the wheel radius, F _z,in is the inboard wheel vertical load, and the μroad friction coefficient.

When the wheels are in a braking state, if the actual braking force of the inner wheels is greater than the maximum longitudinal force, the braking force of the wheels is limited, so that the inner wheels are prevented from generating larger slip, and the vehicle stability in a curve is ensured.

In a preferred embodiment the method of calculating the maximum longitudinal force of the wheel inside the curve comprises:

The application also provides a control system for the curve running of the vehicle, which comprises an acquisition and calculation module, a control module, a driving module and a braking module;

The control module calculates a driving control signal or a braking control signal for the inner vehicle according to the calculated maximum longitudinal force and a real-time braking force of the current vehicle in a braking state or a driving force of the current vehicle in a driving state, and the driving module and the braking module control the braking force of the inner vehicle based on the driving control signal or the driving control signal. The control method in the above embodiment is realized by the acquisition and calculation module, the control module, the driving module and the braking module.

The present embodiment also provides a vehicle including the vehicle curve running control method in the above embodiment or the vehicle curve running control system in the above embodiment. Because this vehicle includes the scheme among the above-mentioned embodiment, consequently realized one kind and possess the vehicle that prevents the inboard wheel of bend from skidding or locking, this vehicle can prevent that inboard wheel from skidding through above-mentioned scheme, has guaranteed whole car acceleration nature when the bend, prevents that inboard wheel from producing great slippage, has guaranteed vehicle stability when the bend.

As shown in fig. 1 to 3, a feedforward control method for preventing a wheel from slipping or locking inside a curve in this embodiment includes the steps of:

Step 1, calculating the front and rear wheel slip angle alpha, the tire side force Fy and the tire vertical load Fz in real time according to a whole vehicle model;

step 2, obtaining an adhesion elliptic curve under the corresponding slip angle according to the parameters calculated in the step 1, and further determining the maximum longitudinal adhesive force Fx_max at the moment;

And 3, comparing the tire longitudinal force Fx obtained in the step 1 with the maximum longitudinal adhesive force Fx_max obtained in the step 2. If the wheel is in a driving state and Fx is larger than or equal to fx_max, the wheel is considered to slip at the moment, braking force is applied to the inner wheel to prevent the wheel from slipping, and the magnitude of the applied braking moment can be calculated by the following formula, wherein T_brk=max (Fx-fx_max, 0) is represented by R, wherein R is the radius of the wheel;

If the wheels are in a braking state and the braking force is greater than or equal to the wheel locking moment, the wheels are considered to be locked at the moment, the braking moment of the inner side wheels is limited, and the wheel locking is prevented.

According to the invention, through innovative feedforward control architecture and high-precision dynamics modeling, core problems of response lag, model precision deficiency and the like in traditional curve stability control are effectively solved, and the safety and operability of the vehicle under the limit turning working condition are remarkably improved.

As shown in fig. 1-3, the present embodiment provides a curve feedforward control method based on a whole vehicle model, which includes the following steps:

s1, building a vehicle model and a tire model and calculating parameters in real time

1. Vehicle dynamics model establishment

The vehicle dynamics equation is established as follows:

F_y,FAcosδ_FA+F_y,RA＝ma_y

Wherein l _FA、l_RA is the distance from the center of mass of the vehicle to the front axle and the rear axle respectively, F _y,FA、F_y,RA is the lateral force of the front and rear wheels respectively, m is the mass of the whole vehicle, J _z is the moment of inertia, delta _FA is the front axle angle of the vehicle, and a _y is the lateral acceleration of the vehicle; Is the vehicle yaw acceleration.

2. Tire slip angle calculation

① Centroid slip angle calculation:

wherein, the The change rate of the vehicle mass center slip angle is shown as a vehicle mass center slip angle, a _y is the vehicle transverse acceleration, and v is the vehicle speed; Is the vehicle yaw rate.

② Calculating the tire slip angle:

Front wheel slip angle:

Wherein alpha _FA is the vehicle front axle slip angle, delta _FA is the vehicle front axle turning angle, beta is the vehicle mass center slip angle, l _FA is the distance from the mass center to the front axle, v is the vehicle speed; Is the vehicle yaw rate.

Rear wheel slip angle:

Wherein alpha _RA is the slip angle of the rear axle of the vehicle, beta is the slip angle of the mass center of the vehicle, l _RA is the distance from the mass center to the rear axle, v is the speed of the vehicle; Is the vehicle yaw rate.

3. Vertical load transfer calculation

Static load distribution:

Wherein F _z,f0、F_z,r0 is static load distributed by a front axle and a rear axle respectively, L _f、l_r is distance from a mass center to the front axle and the rear axle respectively, L is vehicle wheelbase, m is vehicle mass, and g is gravitational acceleration.

Dynamic load transfer (caused by lateral acceleration a _y):

Wherein DeltaF _z is dynamic transfer load, h is centroid height, d is track width, m is whole vehicle mass, and a _y is transverse acceleration.

Inboard wheel vertical load:

F_z,in＝F_z0-ΔF_z

Wherein F _z,in is the inboard wheel load, F _z0 is the static load, and ΔF _z is the dynamic transfer load.

4. Tire force calculation

The lateral force F of the inner driving wheel can be obtained according to the characteristic curve of the tire _y

F_y,FA(α_FA)＝F_z,FA*μ_y,FA(α_FA)

F_y,RA(α_RA)＝F_z,RA*μ_y,RA(α_RA)

Wherein F _y,FA、F_y,RA is front wheel side force and rear wheel side force respectively, F _z,FA、F_z,RA is front wheel vertical load and rear wheel vertical load respectively, mu _y,FA、μ_y,RA is front wheel side attachment coefficient and rear wheel side attachment coefficient respectively, alpha _FA、α_RA is front axle side deflection angle and rear axle side deflection angle of the vehicle respectively;

S2, calculating the adhesion elliptic curve and the maximum longitudinal adhesion force

1. Theory of friction ellipse

Constraint equation:

wherein F _x、F_y、F_z is the tire longitudinal force, lateral force and vertical force, respectively, and mu _x、μ_y is the longitudinal adhesion coefficient and lateral adhesion coefficient, respectively.

Maximum longitudinal force solution, given the current F _y and the vertical load F _z, the solution equation is obtained:

Wherein, F _x,max is the maximum longitudinal force of the tire, F _y、F_z is the lateral force and the vertical force of the tire, and mu _x、μ_y is the longitudinal adhesion coefficient and the lateral adhesion coefficient respectively.

And the high-adhesion pavement parameters are that the friction coefficient mu _x、μ_y is 0.8-1.2, and the high-adhesion pavement parameters correspond to the dry asphalt pavement.

S3, braking moment applying or maintaining logic

1. Slip or lock judgment condition

If F _x≥F_x,max, judging that the inner wheel is about to slip at the moment;

if T _brk≥μF_z,in R, it is determined that the inner wheel is about to lock.

2. Braking torque calculation

T_brk＝max(F_x-F_x,max,0)*R

Wherein, the driving force F _x＝T_e/2R, R is the tire radius. The Max function is the maximum function.

If T _brk≥μF_z,in R is used, triggering a pressure maintaining state, limiting the moment to T _brk＝T_max＝μF_z,in R and preventing the wheel from locking. Wherein R is the radius of the wheel, F _z,in is the vertical load of the inner wheel, and mu road friction coefficient.

Μ represents the peak friction coefficient or the maximum usable friction coefficient of the tire-road combination. It is a scalar quantity representing the ratio of maximum friction force to vertical load (f_max/Fz) that the tire can offer under pure slip (pure longitudinal braking/driving or pure lateral cornering) conditions.

Μx represents the longitudinal friction coefficient. It is the ratio of the longitudinal force (driving force or braking force) Fx actually generated by the tire to the vertical load Fz (μx=fx/Fz).

Μy represents the lateral coefficient of friction. It is the ratio of the lateral force (steering force) Fy actually generated by the tire to the vertical load Fz (μy=fy/Fz).

3. Actuator control

The brake torque is maintained to prevent the wheel locking when the brake torque reaches the locking torque of the inner wheel.

According to the method, the risk of slipping or locking is reduced through accurate model prediction and quick execution, meanwhile, the driving wheel is prevented from reducing torsion, the sufficient power of the vehicle during over-bending is ensured, and the limit of a curve is obviously improved.

As shown in fig. 2, the tire characteristic curve reflects the relationship between the lateral adhesion coefficient and the slip angle, and the lateral force corresponding to the slip angle can be obtained from the curve. Where the first half linear region slope may represent tire cornering stiffness Cy, and exceeding α_μmax represents a tire non-linear region.

As shown in fig. 3, an elliptic adhesion curve is obtained, and according to the curve, the corresponding maximum longitudinal forces under different lateral forces can be determined, so as to determine the tire slip/locking condition at this time, and the braking force to be applied is determined according to different conditions.

It is obvious that the specific implementation of the present invention is not limited by the above-mentioned modes, and that it is within the scope of protection of the present invention only to adopt various insubstantial modifications made by the method conception and technical scheme of the present invention.

Claims

1. A method for controlling vehicle cornering, characterized in that: when the vehicle is cornering, the method includes calculating the maximum longitudinal force of the inner wheel of the curve in real time, and controlling the braking force of the inner wheel based on the maximum longitudinal force and the current braking or driving state of the vehicle to ensure the stability of the vehicle's cornering.

2. A method for controlling vehicle curve driving as described in claim 1, characterized in that: when the wheels of the vehicle traveling on the curve are in a driving state, the actual driving force of the inner wheel is collected and calculated in real time, and the braking force of the inner wheel is controlled based on the actual driving force of the inner vehicle and the magnitude of the maximum longitudinal force.

3. A method for controlling vehicle curve driving as claimed in claim 2, characterized in that when the actual driving force of the inner wheel is greater than the maximum longitudinal force, a braking force is applied to the inner wheel.

4. A method for controlling vehicle driving on a curve as claimed in claim 1, characterized in that: when the wheels of the vehicle driving on the curve are in a braking state, the actual braking force of the inner wheel is collected and calculated in real time, and the braking force of the inner wheel is controlled based on the actual braking force of the inner vehicle and the maximum longitudinal force.

5. A method for controlling vehicle cornering as claimed in claim 4, characterized in that when the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking force is limited.

6. A method for controlling vehicle driving on a curve according to any one of claims 1 to 5, wherein the method for calculating the maximum longitudinal force of the inner wheel of the curve comprises:

(1) Establish a vehicle model and calculate the slip angle and load of the inner wheel of the vehicle in real time;

(2) After calculating the slip angle and load of the inner wheel, the maximum longitudinal adhesion of the inner wheel is determined based on the tire adhesion elliptical curve.

7. A method for controlling vehicle cornering as claimed in claim 2 or 3, characterized in that: when the actual driving force of the inner wheel is greater than the maximum longitudinal force, the torque applying the braking force to the inner wheel is: T_brk = max(Fx-Fx,max,0)*R; where R is the tire radius, Fx is the actual driving force, Fx _,max is the maximum longitudinal force of the inner wheel, and the max function is a maximum value function.

8. A method for controlling vehicle cornering according to claim 4 or 5, characterized in that when the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking torque is limited to be less than or equal to μF _z,in R, where R is the wheel radius; F _z,in is the vertical load on the inner wheel; and μ is the road friction coefficient.

9. A vehicle control system for driving on a curve, characterized by comprising: an acquisition and calculation module, a control module, a drive module, and a brake module;

The acquisition and calculation module is used to calculate the maximum longitudinal force of the inner wheel of the curve in real time when the vehicle is traveling on the curve;

The control module calculates the driving control signal or braking control signal for the inner vehicle based on the calculated maximum longitudinal force and the real-time braking force of the current vehicle in the braking state or the driving force in the driving state. The driving module and the braking module control the braking force of the inner wheel based on the driving control signal or the driving control signal.

10. A vehicle, characterized in that: the vehicle comprises the method for controlling vehicle curve driving according to any one of claims 1 to 8 or the control system for vehicle curve driving according to claim 9.