Vehicle curve driving control method and system and vehicle

Abstract

The invention discloses a control method and system for vehicle curve running and a vehicle. The method comprises the steps that when the vehicle runs on a curve, the maximum longitudinal force of wheels on the inner side of the curve is calculated in real time; and according to the maximum longitudinal force, braking force control is conducted on the inner side wheels in combination with the current braking or driving state of the vehicle, so that the stability of the vehicle running on the curve is guaranteed. The method has the advantages that through the innovative feedforward control architecture and high-precision dynamic modeling, the core problems of response lag, insufficient model precision and the like in traditional curve stability control are effectively solved, and the safety and controllability of the vehicle under the limit turning working condition are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile safety braking control, in particular to a control method and system for vehicle driving on a curve and a vehicle. BACKGROUND

[0002] When a vehicle is turning, load transfer is caused by the centrifugal force, the vertical load of the inner wheel is significantly reduced, and the longitudinal adhesion of the inner wheel is sharply decreased. At this time, if the driver applies driving force or brake operation, the inner wheel is prone to slip or lock due to the longitudinal force exceeding the adhesion limit, and further causes loss of power or unintended yaw of the vehicle.

[0003] Traditional vehicle stability control systems mostly use feedback closed-loop control strategies, mainly triggering brake force adjustment after detecting wheel slip or lock through wheel speed sensors. However, this method has obvious delay, relies on real-time feedback signals to correct control amount, and cannot suppress the potential slip or lock trend in advance. When the system detects abnormal wheel speed, the tire has entered a state of obvious slip or lock, at this time, a large control intervention is needed to stabilize the wheel, the whole control is rough, and due to the delay of intervention, there is a risk of driving safety due to slip or lock. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, provide a control method and system for vehicle driving on a curve and a vehicle, to solve the core problems of response lag and insufficient model accuracy in traditional curve stability control, and significantly improve the safety and maneuverability of the vehicle in extreme turning conditions.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a control method for vehicle driving on a curve, comprising: when the vehicle is driving on a curve, calculating the maximum longitudinal force of the inner wheel of the curve in real time, and controlling the brake force of the inner wheel according to the maximum longitudinal force and the current brake or driving state of the vehicle to ensure the stability of the vehicle driving on the curve.

[0006] When the vehicle driving on the curve is in a driving state, the actual driving force of the inner wheel is collected and calculated in real time, and the brake force of the inner wheel is controlled based on the size of the actual driving force of the inner wheel and the maximum longitudinal force.

[0007] When the actual driving force of the inner wheel is greater than the maximum longitudinal force, brake force is applied to the inner wheel.

[0008] When the vehicle driving on the curve is in a braking state, the actual braking force of the inner wheel is collected and calculated in real time, and the brake force of the inner wheel is controlled based on the size of the actual braking force of the inner wheel and the maximum longitudinal force.

[0009] When the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking force is limited.

[0010] The method for calculating the maximum longitudinal force of the inner wheel in the curve comprises:

[0011] (1) Establish a whole vehicle model to calculate the side slip angle and load of the inner wheel of the vehicle in real time.

[0012] (2) After the side slip angle and load of the inner wheel are calculated, the maximum longitudinal adhesion force of the inner wheel is determined according to the tire adhesion ellipse curve.

[0013] When the actual driving force of the inner wheel is greater than the maximum longitudinal force, the torque of the braking force applied to the inner wheel is T_brk = max (Fx-Fx,max, 0) *R; wherein R is the tire radius, Fx is the real-time driving force, F x,max max is the maximum value function.

[0014] When the actual braking force of the inner wheel is greater than the maximum longitudinal force, the wheel braking force torque is less than or equal to μF z,in R, wherein R is the wheel radius; F z,in is the vertical load of the inner wheel; and μ is the road friction coefficient.

[0015] A control system for vehicle driving in a curve comprises a collection and calculation module, a control module, a driving module and a braking module.

[0016] The collection and calculation module is used to calculate the maximum longitudinal force of the inner wheel in the curve in real time when the vehicle drives in the curve.

[0017] The control module calculates the driving control signal or the braking control signal for the inner vehicle according to the calculated maximum longitudinal force and the real-time braking force in the braking state or the driving force in the driving state of the current vehicle, and 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.

[0018] A vehicle comprises the control method for vehicle driving in a curve or the control system for vehicle driving in a curve.

[0019] The present application has the advantages that: through the innovative feedforward control architecture and high-precision dynamics modeling, the core problems such as response lag and insufficient model precision in traditional curve stability control are effectively solved, and the safety and maneuverability of the vehicle in the extreme turning condition are significantly improved. Compared with the prior art, the control method has shorter control intervention delay and can meet the safety control requirements in the over-turning condition, effectively avoiding the slipping or locking phenomenon of the inner wheel of the vehicle in the over-turning condition, and improving the safety of the over-turning control. BRIEF DESCRIPTION OF DRAWINGS

[0020] Brief description of the drawings and the symbols in the drawings are explained as follows:

[0021] Figure 1 is the flow chart of the control method of the present application;

[0022] Figure 2 is the tire characteristic curve;

[0023] Figure 3 is the schematic diagram of the adhesion force calculation of the adhesion ellipse curve. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application are further explained in detail with reference to the drawings, by describing the optimal embodiments.

[0025] As shown in the drawings, Figure 1 a control method for vehicle driving on a curve is a feedforward control method for preventing the inside wheels from slipping or locking on a curve. The side slip angle and load of the inside wheels during turning are calculated by a vehicle model, and the maximum longitudinal adhesion force of the inside wheels is obtained according to an adhesion ellipse curve. When the wheels are in a driving state, if the driving force of the inside wheels is greater than the maximum longitudinal adhesion force, a braking torque is applied to the inside wheels to prevent the inside wheels from slipping, so that the torque reduction during turning is prevented and the power of the vehicle during curve driving is ensured. When the wheels are in a braking state, if the braking torque of the inside wheels is greater than or equal to the wheel locking torque, the braking force of the inside wheels is limited to prevent the inside wheels from generating a large slip and to ensure the stability of the vehicle.

[0026] Specifically, when the vehicle is driving on a curve, the maximum longitudinal force of the inside wheels is calculated in real time, and the braking force control of the inside wheels is performed according to the maximum longitudinal force and the current braking or driving state of the vehicle to ensure the stability of the vehicle during curve driving.

[0027] When the wheels of the vehicle driving on a curve are in a driving state, the actual driving force of the inside wheels is collected and calculated in real time, and the braking force control of the inside wheels is performed based on the actual driving force of the inside wheels and the maximum longitudinal force. When the actual driving force of the inside wheels is greater than the maximum longitudinal force, a braking force is applied to the inside wheels. When the actual driving force of the inside wheels is greater than the maximum longitudinal force, the torque of the braking force applied to the inside wheels is T_brk = max(Fx-Fx,max, 0) * R; where R is the tire radius, Fx is the real-time driving force, Fx,max is the maximum longitudinal force of the inside wheels, and the max function is the maximum value function. x,max

[0028] ​When the vehicle wheels are in braking state, the actual braking force of the inner wheels is collected in real time, and the braking force control of the inner wheels is performed based on the actual braking force of the inner wheels and the maximum longitudinal force. When the actual braking force of the inner wheels is greater than the maximum longitudinal force, the braking force of the wheels is limited. z,in R, wherein R is the wheel radius; F z,in is the vertical load of the inner wheels; and μ is the road friction coefficient.

[0029] If the actual driving force of the inner wheels exceeds the maximum longitudinal force, braking force is applied to the inner wheels to prevent the inner wheels from slipping and ensure the acceleration of the vehicle on the curve. When the wheels are in 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 to prevent the inner wheels from slipping and ensure the stability of the vehicle on the curve.

[0030] In a preferred embodiment, the method for calculating the maximum longitudinal force of the inner wheels on the curve comprises:

[0031] (1) establishing a vehicle model to calculate the side slip angle and load of the inner wheels of the vehicle in real time;

[0032] (2) after the side slip angle and load of the inner wheels are calculated, the maximum longitudinal adhesion force of the inner wheels is determined according to the adhesion ellipse curve of the tire.

[0033] In an embodiment of the present application, a control system for vehicle driving on a curve is also provided, which comprises a collection and calculation module, a control module, and a driving module and a braking module.

[0034] The collection and calculation module is configured to calculate the maximum longitudinal force of the inner wheels on the curve in real time when the vehicle is driving on the curve. The control module calculates the driving control signal or braking control signal for the inner wheels based on the calculated maximum longitudinal force and the real-time braking force when the vehicle is in braking state or the driving force when the vehicle is in driving state. The driving module and the braking module control the braking force of the inner wheels based on the driving control signal or the braking control signal. The control method in the above embodiments is realized by the collection and calculation module, the control module, and the driving module and the braking module.

[0035] The present embodiment also provides a vehicle comprising the control method for vehicle driving on a curve in the above embodiments or the control system for vehicle driving on a curve in the above embodiments. Since the vehicle comprises the above solutions, a vehicle capable of preventing the inner wheels on the curve from slipping or locking is realized. The vehicle can prevent the inner wheels from slipping, ensure the acceleration of the vehicle on the curve, prevent the inner wheels from slipping, and ensure the stability of the vehicle on the curve.

[0036] As Figures 1-3 shown in the embodiment, the front feed control method for preventing the inside wheel from slipping or locking in the curve includes the following steps:

[0037] Step 1, calculating the side slip angle α, tire lateral force Fy and tire vertical load Fz in real time according to the vehicle model;

[0038] Step 2, obtaining the attachment ellipse curve under the corresponding side slip angle according to the parameters calculated in step 1, and further determining the maximum longitudinal attachment force Fx_max at this time;

[0039] Step 3, comparing the tire longitudinal force Fx obtained in step 1 with the maximum longitudinal attachment force Fx_max obtained in step 2. If the wheel is in the driving state and Fx≥Fx_max, it is considered that the wheel will slip at this time, and the brake force is applied to the inside wheel to prevent the wheel from slipping. The size of the brake torque can be calculated by the following formula: T_brk=max(Fx-Fx_max,0)*R; wherein R is the wheel radius;

[0040] If the wheel is in the braking state and the brake force is greater than or equal to the wheel locking torque, it is considered that the wheel is locked at this time, and the brake torque of the inside wheel is limited to prevent the wheel from locking.

[0041] The present application effectively solves the core problems of response lag and insufficient model precision in traditional curve stability control through innovative front feed control architecture and high-precision dynamics modeling, and significantly improves the safety and maneuverability of the vehicle in extreme turning conditions.

[0042] As Figures 1-3 shown in the embodiment, the front feed control method for preventing the inside wheel from slipping or locking in the curve includes the following steps:

[0043] S1, establishment of vehicle model and tire model and real-time calculation of parameters

[0044] 1. Establishment of vehicle dynamics model

[0045] The vehicle dynamics equation is established as follows:

[0046] F y,FA cosδ FA +F y,RA =ma y

[0047]

[0048] Wherein, l FA , l RA are the distances from the vehicle mass center to the front axle and the rear axle respectively; F y,FA , F y,RAFf, Fr are front and rear wheel side forces; m is the vehicle mass; J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. z J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. FA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. y J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate.

[0049] 2. Tire side slip angle calculation

[0050] 1. Mass center side slip angle calculation:

[0051]

[0052] J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. y J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate.

[0053] 2. Tire side slip angle calculation

[0054] Front wheel side slip angle:

[0055]

[0056] J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. FA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. FA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. FA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate.

[0057] Rear wheel side slip angle:

[0058]

[0059] J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. RA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. RA J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate.

[0060] 3. Vertical load transfer calculation

[0061] Static load distribution:

[0062]

[0063] J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. z,f0 J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. z,r0 J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. f J is the rotational inertia; δ is the vehicle front axle steering angle; a is the vehicle lateral acceleration; v is the vehicle speed; ω is the vehicle yaw rate. rrespectively, are the distances from the center of mass to the front and rear axles; L is the wheelbase of the vehicle; m is the mass of the vehicle; and g is the acceleration of gravity.

[0064] Dynamic load transfer (lateral acceleration a y caused by):

[0065]

[0066] where ΔF z is the dynamic load transfer; h is the height of the center of mass; d is the wheel track; m is the mass of the vehicle; and a y is the lateral acceleration.

[0067] Inner side wheel vertical load:

[0068] F z,in = F z0 - ΔF z

[0069] where F z,in is the inner side wheel load; F z0 is the static load; and ΔF z is the dynamic load transfer.

[0070] 4. Tire force calculation

[0071] From the tire characteristic curve, the inner side drive wheel lateral force F y

[0072] F y,FA (α FA ) = F z,FA * μ y,FA (α FA )

[0073] F y,RA (α RA ) = F z,RA * μ y,RA (α RA )

[0074] where F y,FA and F y,RA are the front and rear wheel lateral forces, respectively; F z,FA and F z,RA are the front and rear wheel vertical loads, respectively; μ y,FA and μ y,RA are the front and rear wheel lateral adhesion coefficients, respectively; and α FA and α RA are the vehicle front and rear axle side slip angles, respectively.

[0075] S2, adhesion ellipse curve and maximum longitudinal adhesion force calculation

[0076] 1. Friction ellipse theory

[0077] Constraint equations:

[0078] Among them, F x 、F y 、F z are the tire longitudinal force, lateral force and vertical force respectively; μ x 、μ y are the longitudinal adhesion coefficient and the lateral adhesion coefficient, respectively.

[0079] Maximum longitudinal force solution: Given the current F y With vertical load F z , solving the equation gives:

[0080]

[0081] Among them, F x,max Maximum longitudinal force of the tire; F y 、F z are the lateral force and vertical force of the tire respectively; μ x 、μ y are the longitudinal adhesion coefficient and the lateral adhesion coefficient, respectively.

[0082] High adhesion road parameters: friction coefficient μ x 、μ y Take 0.8 to 1.2, corresponding to dry asphalt pavement.

[0083] S3, braking torque application or maintenance logic

[0084] 1. Slip or lock judgment conditions

[0085] If F x ≥F x,max , judging that the inner wheel is about to slip;

[0086] If T brk ≥μF z,in R, it is determined that the inner wheel is about to lock.

[0087] 2. Braking torque calculation

[0088] T brk =max(F x -F x,max ,0)*R

[0089] Among them, the driving force F x =T e / 2R, R is the tire radius. Max function is the maximum value function.

[0090] If T brk ≥μFz,in R, trigger the pressure maintaining state, limit the torque to T brk = T max = μF z,in R, prevent the wheel from locking. Where R is the wheel radius; F z,in is the vertical load of the inner wheel; μ is the road friction coefficient.

[0091] μ: represents the peak friction coefficient or the maximum available friction coefficient of the tire-road combination. It is a scalar, representing the ratio of the maximum friction force that the tire can provide to the vertical load (F_max / Fz) under pure slip (pure longitudinal braking / driving or pure lateral cornering) conditions.

[0092] μx: represents the longitudinal friction coefficient. It is the ratio of the actual longitudinal force (driving force or braking force) Fx generated by the tire to the vertical load Fz (μx = Fx / Fz).

[0093] μy: represents the lateral friction coefficient. It is the ratio of the actual lateral force (steering force) Fy generated by the tire to the vertical load Fz (μy = Fy / Fz).

[0094] 3. Actuator control

[0095] Apply a step-by-step braking torque to the inner wheel through the brake-by-wire system to avoid oscillation caused by step response; maintain the braking torque to prevent the wheel from locking when the inner wheel reaches the locking torque.

[0096] This method reduces the risk of slipping or locking through precise model prediction and rapid execution, while preventing the driven wheel from reducing torque, ensuring sufficient vehicle power during cornering, and significantly improving cornering limits.

[0097] As Figure 2 shown, it is a tire characteristic curve, reflecting the relationship between the lateral adhesion coefficient and the side slip angle, i.e. the lateral force corresponding to the side slip angle can be obtained according to this curve. The slope of the first half linear region can represent the tire side stiffness Cy, and beyond α_μMax represents the nonlinear region of the tire.

[0098] As Figure 3 shown, it is an elliptical adhesion curve, which can be used to determine the maximum longitudinal force corresponding to different lateral forces, and thus determine the tire slip / lock condition at this time, and determine the braking force required for different conditions.

[0099] Obviously, the specific implementation of the present application is not limited by the above-mentioned manner, as long as various non-essential improvements are made using the method concept and technical solution of the present application, they are within the protection scope of the present application.

Claims

1. A method for controlling a vehicle traveling on a curve, characterized in that: This includes calculating the maximum longitudinal force of the inner wheel of the curve in real time when the vehicle is traveling on a curve, 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 driving on the curve.

2. The method for controlling a vehicle traveling on a curve according to claim 1, wherein: When the wheels of a vehicle traveling on a curve are in 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. The method for controlling a vehicle traveling on a curve according to claim 2, wherein: When the actual driving force of the inner wheel is greater than the maximum longitudinal force, braking force is applied to the inner wheel.

4. The method for controlling a vehicle traveling on a curve according to claim 1, wherein: When the wheels of a vehicle traveling on a 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. The method for controlling a vehicle traveling on a curve according to claim 4, wherein: 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, characterized in that: The calculation method of the maximum longitudinal force of the wheel on the inside of the curve includes: (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 a vehicle traveling on a curve according to 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 of the braking force applied 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, and F x，max is the maximum longitudinal force of the inner wheel; max function is the maximum value function.

8. A method for controlling a vehicle traveling on a curve 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; μ is the road friction coefficient.

9. A control system for a vehicle traveling on a curve, characterized by: Including acquisition and calculation module, control module, drive module and 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 includes the method for controlling vehicle curve driving as described in any one of claims 1 to 8 or the control system for vehicle curve driving as described in claim 9.

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