CN117400922A - A vehicle steering control method and control system based on parking system - Google Patents

Abstract

The invention discloses a vehicle steering control method and control system based on a parking system, which includes: establishing a vehicle steering angle model based on wheel speed according to vehicle steering parameters; calculating the vehicle inner front wheel turning radius and Vehicle steering angle; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle and the steering angle ratio of the front wheel and the rear wheel on the outside of the vehicle. the second control target value; according to the first control target value and the second control target value, the steering angles of the vehicle's inner and vehicle outer front wheels are respectively adjusted, so that the adjusted steering angle ratio between the vehicle's inner front wheel and the rear wheel is equal to the first control target value and the ratio of the steering angle of the vehicle's outer front wheel to the rear wheel is equal to the second target value. The invention can realize freer, more flexible and wider angle control of the parking system, ensuring the significance of the parking system.

Description

A vehicle steering control method and control system based on parking system

Technical field

The invention belongs to the field of automatic parking of vehicles, and specifically relates to a vehicle steering control method and control system based on a parking system.

Background technique

Currently, the relevant parking system control methods mostly use a single steering unit for control. For example, most vehicles can only steer and operate the front wheels to ensure that the vehicle has a unique control trajectory when responding to the parking system request. This way, Ensure the precise performance of parking maneuvers.

In order to ensure the safety of the mechanical system, the steering angle that the parking system can control is generally 93%-95% of the driver's maximum turning angle. Therefore, the current parking system control vehicle can achieve about 90% of the actual minimum turning radius of the vehicle.

Some of the existing high-end models use rear-wheel steering systems, which can further reduce the actual minimum turning radius of the vehicle, but they also have obvious shortcomings, among which the ones related to the parking system are 1. The steering radius that the parking system can control It is still smaller than the minimum controllable radius of the driver; 2. To control 4-way steering, the calculation of vehicle position and angle relationship is complex, requiring higher path planning and control system logic, and higher computing power and algorithm capabilities.

The current technical solution is generally applicable to the widely used vehicle models whose rear wheels do not follow the steering. When the EPS controller receives the angle request from the parking system, it controls the front wheels of the vehicle to a predetermined position. However, in the face of increasingly stringent parking demands, the increasingly stringent standards in the parking field have raised the parking industry level from the limit parking space of vehicle length + 1m to the industry level of vehicle length + 0.8m. At present, many car companies are challenging the limit of vehicle length plus 0.6m or 0.5m, but due to actual capabilities, it is difficult to make further breakthroughs. The limit level of vehicle length plus 0.6m or 0.5m is still lower than the limit level of driver driving, and the significance of the parking system is lost in some working conditions.

Contents of the invention

The purpose of the present invention is to provide a vehicle steering control method and control system based on a parking system, which can realize a freer, more flexible and wider range of angle control of the parking system, and ultimately achieve a performance index of the parking system that is not lower than that of driving. The level of staff ensures the significance of the parking system.

In order to solve the above technical problems, the technical solution of the present invention is: a vehicle steering control method based on a parking system, which includes the following steps:

According to the vehicle steering parameters, a vehicle steering angle model based on wheel speed is established; the vehicle steering parameters include at least the instantaneous center of speed when the vehicle turns, wheel wheel base, vehicle wheel base, inner wheel radius, outer wheel radius, inner wheel speed, outer wheel speed, The inner wheel axis speed and the outer wheel axis speed;

According to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius of the inner front wheel of the vehicle, and the wheel base is calculated to obtain the turning radius of the vehicle's inner front wheel. The vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel are calculated. The vehicle steering angle is calculated based on the relationship;

Perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle and the second control target value of the steering angle ratio of the front wheel to the rear wheel on the outside of the vehicle. target value;

The vehicle steering angle is used as the steering angle of the vehicle's inner rear wheel and the outer rear wheel, and the steering angles of the vehicle's inner and vehicle outer front wheels are respectively adjusted according to the first control target value and the second control target value, so that the adjusted vehicle inner front wheel The steering angle ratio between the wheel and the rear wheel is equal to the first control target value and the steering angle ratio between the front wheel and the rear wheel on the outer side of the vehicle is equal to the second target value.

The relationship between vehicle steering angle, vehicle wheelbase and vehicle inner front wheel turning radius is expressed as:

tanδ＝L/R

Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle.

The method for calculating the turning radius of the inside front wheel of the vehicle is:

r _inside = r _outside

Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; _inside r and _outside r are the radii of the inner and outer wheels respectively, D is the vehicle wheelbase, L is the wheelbase of the vehicle, _{the inside} of ω is the rotation speed of the inner wheel, and _{the outside of} ω is the rotation speed of the outer wheel, which can be obtained by measurement;

Together we get:

Solutions have to:

Calculate the turning radius value of the vehicle's inner front wheel.

The calculation method of the first control target value and the second control target value is:

The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as:

Let the instantaneous center of speed of the adjusted vehicle when turning be O', the adjusted steering angle be β, the adjusted turning radius of the inside front wheel of the vehicle be R', and the adjusted turning radius of the inside _rear wheel of the vehicle be R', Then there are:

sinβ=L/R'

tanβ＝L/R_内'

Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ;

Simplify to get:

The first control target value K ₁ is calculated;

Similarly there are:

Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ;

Simplify to get:

The second control target value K ₂ is calculated.

The body stability control system ESC controls the braking of the vehicle's inner and outer wheels respectively.

Also provided is a control system including:

The sensor group is used to collect vehicle steering parameters. The vehicle steering parameters at least include the instant center of speed when the vehicle turns, wheel wheel base, vehicle wheel base, inner wheel radius, outer wheel radius, inner wheel speed, outer wheel speed, inner wheel axis speed and Outer wheel axis speed;

The parking system is used to calculate the vehicle steering angle based on the relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel;

The central controller is used to establish a vehicle steering angle model based on wheel speed according to the vehicle steering parameters; according to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius of the inner front wheel of the vehicle, and the wheel track is calculated to obtain the vehicle Turning radius of the inner front wheel; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the inner front wheel and the rear wheel of the vehicle and the steering angle of the vehicle's outer front wheel and rear wheel. The second control target value of the ratio of angle, so that the adjusted steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle is equal to the first control target value and the steering angle ratio between the front wheel and the rear wheel on the outside of the vehicle is equal to the second target value.

The relationship between vehicle steering angle, vehicle wheelbase and vehicle inner front wheel turning radius is expressed as:

tanδ＝L/R

Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle.

The method for calculating the turning radius of the inside front wheel of the vehicle is:

r _inside = r _outside

Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; _inside v and _outside v are the axis speeds of the inner and outer wheels respectively, _inside r and _outside r are the radii of the inner wheel and the outer wheel respectively, D is the wheelbase of the vehicle, L is the wheelbase of the vehicle, _inside ω is the rotation speed of the inner wheel, and _outside ω is the rotation speed of the outer wheel, all of which can be obtained by measurement;

Together we get:

Solutions have to:

Calculate the turning radius value of the vehicle's inner front wheel.

The calculation method of the first control target value and the second control target value is:

The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as:

Let the instantaneous center of speed of the adjusted vehicle when turning be O', the adjusted steering angle be β, the adjusted turning radius of the inside front wheel of the vehicle be R', and the adjusted turning radius of the inside _rear wheel of the vehicle be R', Then there are:

sinβ=L/R'

tanβ＝L/R_内'

Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ;

Simplify to get:

The first control target value K ₁ is calculated;

Similarly there are:

Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ;

Simplify to get:

The second control target value K ₂ is calculated.

The body stability control system ESC controls the braking of the vehicle's inner and outer wheels respectively.

Compared with the prior art, the beneficial effects of the present invention are:

Safety benefits: This invention can be used under various environmental conditions, especially a parking system vehicle steering control method, to ensure parking control with a smaller turning radius during the parking process, ensure scene universality, and thereby ensure driving Safety.

Economic benefits: Without adding other equipment, the solution design is completed based on a parking system vehicle steering control method, saving costs.

Enterprise benefits: This invention is simple and practical, suitable for all vehicle models, can interact with rear-wheel steering systems of various models, and operates in a modular manner.

Description of the drawings

Figure 1 is a schematic flow diagram of an embodiment of the present invention;

Figure 2 is a schematic diagram comparing the processes of the embodiment of the present invention and the existing parking system;

Figure 3 is a schematic diagram of a connection structure applied to a vehicle according to an embodiment of the present invention;

Figure 4 is a schematic diagram of a vehicle steering angle model based on wheel speed in an embodiment of the present invention;

Figure 5 is a schematic diagram of adjusting the steering angle of the inner front wheel of the vehicle in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The technical solution of the present invention is:

Example 1:

As shown in Figure 1, a vehicle steering control method based on a parking system includes the following steps:

According to the vehicle steering parameters, a vehicle steering angle model based on wheel speed is established; as shown in Figure 4, the vehicle steering parameters at least include the instantaneous center of speed O when the vehicle turns, the wheel wheelbase L, the vehicle wheel base D, and the _inner wheel radius r. , the outer wheel radius r _{is outside} , the inner wheel speed is ω _inside , the outer wheel speed is ω _outside , the inner wheel axis speed is v _inside and the outer wheel axis speed is v _outside ;

According to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius R of the inside front wheel of the vehicle, and the wheel track is calculated to obtain the turning radius R of the vehicle's inside front wheel. The vehicle steering angle δ is related to the vehicle wheelbase, the vehicle's inside front wheel. The vehicle steering angle δ is calculated from the relationship between the wheel turning radius;

Perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle and the second control target value of the steering angle ratio of the front wheel to the rear wheel on the outside of the vehicle. target value;

The steering angle of the vehicle is taken as the steering angle of the inner rear wheel and the outer rear wheel of the vehicle (because the direction of the rear wheel of the vehicle is always the same as the direction of the vehicle, the steering angle of the inner rear wheel and the outer rear wheel of the vehicle can be understood as the steering angle of the vehicle after steering and The angle between the vehicle's orientation before steering occurs, and the steering angle control of the vehicle's front wheels is also based on the definition of the angle between the vehicle's orientation after steering and the vehicle's orientation before steering), according to the first control target value and the second The control target value corresponds to adjusting the steering angle of the front wheel on the inside of the vehicle and the outside of the vehicle respectively, so that the adjusted steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle is equal to the first control target value and the steering angle of the front wheel and the rear wheel on the outside of the vehicle. The ratio is equal to the second target value.

The relationship between vehicle steering angle, vehicle wheelbase and vehicle inner front wheel turning radius is expressed as:

tanδ＝L/R

Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle. Under normal circumstances, this steering angle δ is theoretically basically the same as the steering angle controlled by the EPS steering controller and the steering wheel end (or has a specific proportional relationship). The existing project parking system controls the steering angle controlled by the steering controller and the steering wheel end to achieve the control target. However, in the present invention, because the vehicle steering angle δ is not equal to the steering angle controlled by the steering brake and the steering wheel end under certain conditions, Therefore, the control target of the present invention is δ _request (i.e. β). The subsequent braking and steering systems adjust the wheel speed relationship to make δ approach the δ _request to achieve the control purpose.

The method for calculating the turning radius of the inside front wheel of the vehicle is:

r _inside = r _outside

Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; v _inside and v _outside are the axis speeds of the inner and outer wheels respectively, r _inside and r _outside are the radii of the inner wheel and the outer wheel respectively, D is the wheelbase of the vehicle, L is the wheelbase of the vehicle, _inside ω is the rotation speed of the inner wheel, and _outside ω is the rotation speed of the outer wheel, all of which can be obtained by measurement;

Together we get:

Solutions have to:

Calculate the turning radius value of the vehicle's inner front wheel.

Analyzing the front and rear wheels on one side of the vehicle separately, the rear wheels of the parking system of the existing project completely follow, that is, the motion relationship between the front wheels and the rear wheels is a fixed geometric relationship.

Therefore, when the present invention is not used, the steering radius of the vehicle and the front wheel steering angle are completely positively correlated.

Right now

However, the present invention requires braking control of the front and rear wheels simultaneously. The control target β needs to be smaller than the front wheel steering angle δ, which achieves the purpose of reducing the radius in the same scenario (that is, when δ is consistent).

The calculation method of the first control target value and the second control target value is:

The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as:

As shown in Figure 5, let the instantaneous center of speed when the vehicle turns after adjustment be O', the steering angle after adjustment be β, the turning radius of the inside front wheel of the vehicle after adjustment be R', and the inside rear wheel turn of the vehicle after adjustment If the radius is _within R', then there is:

sinβ=L/R'

tanβ＝L/R_内'

Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ;

Simplify to get:

The first control target value K ₁ is calculated;

Similarly there are:

Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ;

Simplify to get:

The second control target value K ₂ is calculated.

The body stability control system ESC controls the braking of the vehicle's inner and outer wheels respectively.

Example 2:

A control system is also provided, as shown in Figure 3, including:

The sensor group is used to collect vehicle steering parameters. The vehicle steering parameters at least include the instant center of speed when the vehicle turns, wheel wheel base, vehicle wheel base, inner wheel radius, outer wheel radius, inner wheel speed, outer wheel speed, inner wheel axis speed and Outer wheel axis speed;

The parking system is used to calculate the vehicle steering angle based on the relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel;

The central controller is used to establish a vehicle steering angle model based on wheel speed according to the vehicle steering parameters; according to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius of the inner front wheel of the vehicle, and the wheel track is calculated to obtain the vehicle Turning radius of the inner front wheel; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the inner front wheel and the rear wheel of the vehicle and the steering angle of the vehicle's outer front wheel and rear wheel. The second control target value of the ratio of angle, so that the adjusted steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle is equal to the first control target value and the steering angle ratio between the front wheel and the rear wheel on the outside of the vehicle is equal to the second target value.

The relationship between vehicle steering angle, vehicle wheelbase and vehicle inner front wheel turning radius is expressed as:

tanδ＝L/R

Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle.

The method for calculating the turning radius of the inside front wheel of the vehicle is:

r _inside = r _outside

Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; _inside r and _outside r are the radii of the inner and outer wheels respectively, D is the vehicle wheelbase, L is the wheelbase of the vehicle, _{the inside} of ω is the rotation speed of the inner wheel, and _{the outside of} ω is the rotation speed of the outer wheel, which can be obtained by measurement;

Together we get:

Solutions have to:

Calculate the turning radius value of the vehicle's inner front wheel.

The calculation method of the first control target value and the second control target value is:

The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as:

Let the instantaneous center of speed of the adjusted vehicle when turning be O', the adjusted steering angle be β, the adjusted turning radius of the inside front wheel of the vehicle be R', and the adjusted turning radius of the inside _rear wheel of the vehicle be R', Then there are:

sinβ=L/R'

tanβ＝L/R_内'

Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ;

Simplify to get:

The first control target value K ₁ is calculated;

Similarly there are:

Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ;

Simplify to get:

The second control target value K ₂ is calculated.

The body stability control system ESC controls the braking of the vehicle's inner and outer wheels respectively.

The solution consists of a four-wheel steering system that supports the basic structure designed by the present invention, a central parking controller (on which a parking system vehicle steering control method is stored), CAN bus, EPS controller, ESC\TCU and other controllers , wheel speed sensor and several other parts.

The wheel speed sensor provides wheel speed information. Generally, a wheel speed sensor has 48 gears (96 pulses) to provide accurate wheel speed support for the present invention, ensuring that the present invention can complete the calculation of the vehicle's angle and attitude through the wheel speed difference of the four wheels, laying the foundation for further vehicle control.

The vehicle CAN bus is used to provide the collected necessary vehicle signals to the central controller for processing by the central controller and return control instructions processed by the central controller;

The central controller is used for 1) storage and calculation of the method of the present invention; 2) storage of the angle control meter module; 3) algorithm storage of the brake request control module; 4) storage of algorithm programs for other normal functions;

The EPS controller is used for unified execution of angle requests in the present invention;

The ESC controller is used to complete the automatic request of the parking system; in the present invention, it is used to distribute the different braking forces of the four wheels to ultimately achieve the purpose of collaborative control.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements, etc., made within the spirit and principles of the present invention, All should be included in the protection scope of the present invention.

Claims (10)

1. A vehicle steering control method based on a parking system, characterized in that it includes the following steps: According to the vehicle steering parameters, a vehicle steering angle model based on wheel speed is established; the vehicle steering parameters include at least the instantaneous center of speed when the vehicle turns, wheel wheel base, vehicle wheel base, inner wheel radius, outer wheel radius, inner wheel speed, outer wheel speed, The inner wheel axis speed and the outer wheel axis speed; According to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius of the inner front wheel of the vehicle, and the wheel base is calculated to obtain the turning radius of the vehicle's inner front wheel. The vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel are calculated. The vehicle steering angle is calculated based on the relationship; Perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle and the second control target value of the steering angle ratio of the front wheel to the rear wheel on the outside of the vehicle. target value; The vehicle steering angle is used as the steering angle of the vehicle's inner rear wheel and the outer rear wheel, and the steering angles of the vehicle's inner and vehicle outer front wheels are respectively adjusted according to the first control target value and the second control target value, so that the adjusted vehicle inner front wheel The steering angle ratio between the wheel and the rear wheel is equal to the first control target value and the steering angle ratio between the front wheel and the rear wheel on the outer side of the vehicle is equal to the second target value. 2. A vehicle steering control method based on a parking system according to claim 1, characterized in that the relationship between the vehicle steering angle, the vehicle wheelbase, and the vehicle inner front wheel turning radius is expressed as: tanδ＝L/R Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle. 3. A vehicle steering control method based on a parking system according to claim 2, characterized in that the method for calculating the turning radius of the vehicle's inner front wheel is: r _inside = r _outside Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; _inside v and _outside v are the axis speeds of the inner and outer wheels respectively, _inside r and _outside r are the radii of the inner wheel and the outer wheel respectively, D is the wheelbase of the vehicle, L is the wheelbase of the vehicle, _inside ω is the rotation speed of the inner wheel, and _outside ω is the rotation speed of the outer wheel, all of which can be obtained by measurement; Together we get: Solutions have to: Calculate the turning radius value of the vehicle's inner front wheel. 4. A vehicle steering control method based on a parking system according to claim 3, characterized in that the calculation method of the first control target value and the second control target value is: The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as: Let the instantaneous center of speed of the adjusted vehicle when turning be O', the adjusted steering angle be β, the adjusted turning radius of the inside front wheel of the vehicle be R', and the adjusted turning radius of the inside _rear wheel of the vehicle be R', Then there are: sinβ=L/R' tanβ＝L/R_内' Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ; Simplify to get: The first control target value K ₁ is calculated; Similarly there are: Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ; Simplify to get: The second control target value K ₂ is calculated. 5. A vehicle steering control method based on a parking system according to claim 1, characterized in that the vehicle body stability control system ESC is used to perform braking control on the inner wheels and outer wheels of the vehicle respectively. 6. A control system using a vehicle steering control method based on a parking system as claimed in claim 1, characterized in that it includes: The sensor group is used to collect vehicle steering parameters. The vehicle steering parameters include at least the instantaneous center of speed when the vehicle turns, wheelbase, average steering angle of the vehicle, vehicle wheelbase, inner wheel radius, outer wheel radius, inner wheel speed, and outer wheel speed. , the inner wheel axis speed and the outer wheel axis speed; The parking system is used to calculate the vehicle steering angle based on the relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel; The central controller is used to establish a vehicle steering angle model based on wheel speed according to the vehicle steering parameters; according to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed, the turning radius of the inner front wheel of the vehicle, and the wheel track is calculated to obtain the vehicle Turning radius of the inner front wheel; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the steering angle ratio between the inner front wheel and the rear wheel of the vehicle and the steering angle of the vehicle's outer front wheel and rear wheel. The second control target value of the ratio of angle, so that the adjusted steering angle ratio between the front wheel and the rear wheel on the inside of the vehicle is equal to the first control target value and the steering angle ratio between the front wheel and the rear wheel on the outside of the vehicle is equal to the second target value. 7. The control system according to claim 6, characterized in that the relationship between the vehicle steering angle, the vehicle wheelbase, and the vehicle inner front wheel turning radius is expressed as: tanδ＝L/R Among them, δ is the steering angle of the vehicle, L is the wheelbase of the vehicle, and R is the turning radius of the inside front wheel of the vehicle. 8. The control system according to claim 7, wherein the method for calculating the turning radius of the vehicle's inner front wheel is: r _inside = r _outside Among them, ω ₀ is the turning angular speed of the vehicle, _inside R is the turning radius of the inner rear wheel of the vehicle, and _outside R is the turning radius of the outer rear wheel of the vehicle; _inside v and _outside v are the axis speeds of the inner and outer wheels respectively, _inside r and _outside r are the radii of the inner wheel and the outer wheel respectively, D is the wheelbase of the vehicle, L is the wheelbase of the vehicle, _inside ω is the rotation speed of the inner wheel, and _outside ω is the rotation speed of the outer wheel, all of which can be obtained by measurement; Together we get: Solutions have to: Calculate the turning radius value of the vehicle's inner front wheel. 9. The control system according to claim 8, characterized in that the calculation method of the first control target value and the second control target value is: The rotational speeds of the front and rear wheels on the inside of the vehicle are expressed as: Let the instantaneous center of speed of the adjusted vehicle when turning be O', the adjusted steering angle be β, the adjusted turning radius of the inside front wheel of the vehicle be R', and the adjusted turning radius of the inside _rear wheel of the vehicle be R', Then there are: sinβ=L/R' tanβ＝L/R_内' Among them, ω _{within the front} is the speed of the vehicle's inside front wheel, ω _{within the rear} is the vehicle's inside rear wheel speed, v _{within the front is the vehicle's inside front wheel speed, v within the rear} is the vehicle's inside rear wheel speed, r _{within the front} is the vehicle's inside front wheel Radius, r _{inside rear} is the radius of the vehicle’s inside rear wheel, r _{inside front} = r _{inside rear} ; Simplify to get: The first control target value K ₁ is calculated; Similarly there are: Among them, ω _{outer front} is the rotation speed of the vehicle outer front wheel, ω _{outer rear} is the vehicle outer rear wheel rotation speed, r _{outer front} is the vehicle outer front wheel radius, r _{outer rear} is the vehicle outer rear wheel radius, r _{outer front} = r _{outer rear} ; Simplify to get: The second control target value K ₂ is calculated. 10. The control system according to claim 6, characterized in that the vehicle body stability control system ESC performs braking control on the inner wheels and outer wheels of the vehicle respectively.