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

Abstract

The present invention discloses a vehicle steering control method and control system based on a parking system, including: establishing a vehicle steering angle model based on wheel speed according to vehicle steering parameters; calculating the turning radius of the inner front wheel and the vehicle steering angle of the vehicle according to the vehicle steering angle model; performing braking control on the inner and outer wheels of the vehicle respectively, and calculating a first control target value of the ratio of the steering angles between the inner front wheel and the rear wheel of the vehicle and a second control target value of the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle; respectively adjusting the steering angles of the inner front wheel and the outer front wheel of the vehicle according to the first control target value and the second control target value, so that the ratio of the steering angles between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle is equal to the second target value. The present invention can achieve more free, flexible and wider-range angle control of the parking system, ensuring the significance of the parking system.

Description

Technical Field

[0001] The present invention belongs to the field of vehicle automatic parking, and particularly relates to a vehicle steering control method and control system based on a parking system. Background Art

[0002] Currently, most of the related parking system control methods use a single steering unit for control. For example, the vast majority of vehicles can only steer and operate the front wheels to ensure that there is a unique corresponding control trajectory when the vehicle responds to the parking system request, so as to ensure the precise performance of the parking action execution.

[0003] In order to ensure the safety of the mechanical system, the steering angle that its parking system can control is generally 93%-95% of the maximum steering angle of the driver. Therefore, currently, the parking system can control the vehicle to achieve about 90% of the actual minimum turning radius of the vehicle.

[0004] Some existing high-end models adopt a rear-wheel steering system, which can further reduce the actual minimum turning radius of the vehicle, but it also has obvious disadvantages. Those related to the parking system are: 1. The turning radius that its parking system can control is still smaller than the minimum radius that the driver can control; 2. Controlling four-wheel steering requires complex calculation of the vehicle position and angle relationship, requires a higher path planning and control system logic, and requires higher computing power guarantee and algorithm capabilities.

[0005] The current technical solutions are generally applicable to the models with non-follow-up rear-wheel steering that are widely used at present. 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 requirements, the continuously stringent standards in the parking field have improved the parking industry level from the limit parking space of vehicle length + 1m to the industry level of vehicle length + 0.8m. Currently, many vehicle manufacturers are challenging the limit levels of vehicle length + 0.6m or 0.5m, but limited by the actual capabilities, it is difficult to make further breakthroughs. The limit levels of vehicle length + 0.6m or 0.5m are still lower than the limit levels of driver driving, and the significance of the parking system is lost in some working conditions. Summary of the Invention

[0006] 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 more free, flexible and larger-range angle control of the parking system, and ultimately ensure that the performance index of the parking system is not lower than that of the driver, thus guaranteeing the significance of the parking system.

[0007] To solve the above technical problems, the technical solution of the present invention is: a vehicle steering control method based on a parking system, comprising the following steps:

[0008] Based on the vehicle steering parameters, a vehicle steering angle model based on wheel speeds is established; the vehicle steering parameters at least include the instantaneous center of speed when the vehicle turns, the wheelbase of the vehicle, the track width of the vehicle, the inner wheel radius, the outer wheel radius, the inner wheel speed, the outer wheel speed, the inner wheel axle speed, and the outer wheel axle speed;

[0009] According to the vehicle steering angle model, the relationship between the inner wheel speed, the outer wheel speed and the turning radius of the inner front wheel of the vehicle and the wheel track width is calculated to obtain the turning radius of the inner front wheel of the vehicle, and the relationship between the vehicle steering angle and the vehicle wheelbase and the turning radius of the inner front wheel of the vehicle is calculated to obtain the vehicle steering angle;

[0010] Brake control is respectively performed on the inner wheel and the outer wheel of the vehicle, and a first control target value of the ratio of the steering angles between the inner front wheel and the rear wheel of the vehicle and a second control target value of the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle are calculated;

[0011] Taking the vehicle steering angle as the steering angles of the inner rear wheel and the outer rear wheel of the vehicle, the steering angles of the inner front wheel and the outer front wheel of the vehicle are respectively adjusted according to the first control target value and the second control target value, so that the ratio of the steering angles between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle is equal to the second target value.

[0012] The relationship between the vehicle steering angle, the vehicle wheelbase and the turning radius of the inner front wheel of the vehicle is expressed as:

[0013] tanδ=L / R

[0014] Where, δ is the vehicle steering angle, L is the vehicle wheelbase, and R is the turning radius of the inner front wheel of the vehicle.

[0015] The method for calculating the turning radius of the inner front wheel of the vehicle is:

[0016]

[0017]

[0018] r 内 =r 外

[0019] Where, ω0 is the vehicle turning angular velocity, R 内 is the turning radius of the inner rear wheel of the vehicle, R 外 is the turning radius of the outer rear wheel of the vehicle; r 内 、r 外 are respectively the radii of the inner wheel and the outer wheel, D is the vehicle track width, L is the vehicle wheelbase, ω 内 is the inner wheel speed, ω 外 is the outer wheel speed, and all can be obtained by measurement;

[0020] Simultaneous equations yield:

[0021]

[0022] The solution is:

[0023]

[0024] The turning radius value of the inner front wheel of the vehicle is calculated.

[0025] The calculation methods of the first control target value and the second control target value are as follows:

[0026] The rotational speeds of the inner front wheel and the rear wheel of the vehicle are expressed as:

[0027]

[0028]

[0029] Let the instantaneous center of speed of the vehicle during turning after adjustment be O', the steering angle after adjustment be β, the turning radius of the inner front wheel of the vehicle after adjustment be R', and the turning radius of the inner rear wheel of the vehicle after adjustment be R 内 ', then there is:

[0030] sinβ = L / R'

[0031] tanβ = L / R 内 '

[0032]

[0033] Among them, ω 内前 is the rotational speed of the inner front wheel of the vehicle, ω 内后 is the rotational speed of the inner rear wheel of the vehicle, v 内前 is the speed of the inner front wheel of the vehicle, v 内后 is the speed of the inner rear wheel of the vehicle, r 内前 is the radius of the inner front wheel of the vehicle, r 内后 is the radius of the inner rear wheel of the vehicle, r 内前 = r 内后 ;

[0034] After simplification, it is obtained:

[0035]

[0036] The first control target value K1 is calculated;

[0037] Similarly, there is:

[0038]

[0039] Among them, ω 外前 is the rotational speed of the outer front wheel of the vehicle, ω 外后is the rotational speed of the outer rear wheel of the vehicle, r 外前 is the radius of the outer front wheel of the vehicle, r 外后 is the radius of the outer rear wheel of the vehicle, r 外前 = r 外后 ;

[0040] After simplification, we get:

[0041]

[0042] Calculate the second control target value K2.

[0043] The electronic stability control system ESC performs braking control on the inner wheels and outer wheels of the vehicle respectively.

[0044] A control system is also provided, including:

[0045] A sensor group for collecting vehicle steering parameters, where the vehicle steering parameters at least include the instantaneous center of speed, wheelbase, vehicle track, inner wheel radius, outer wheel radius, inner wheel rotational speed, outer wheel rotational speed, inner wheel axle center speed, and outer wheel axle center speed when the vehicle is turning;

[0046] A parking system for calculating the vehicle steering angle based on the relationship between the vehicle steering angle, vehicle wheelbase, and turning radius of the inner front wheel of the vehicle;

[0047] A central controller for establishing a vehicle steering angle model based on wheel speed according to the vehicle steering parameters; calculating the turning radius of the inner front wheel of the vehicle based on the relationship between the inner wheel rotational speed, outer wheel rotational speed, turning radius of the inner front wheel of the vehicle, and vehicle track according to the vehicle steering angle model; performing braking control on the inner wheels and outer wheels of the vehicle respectively, calculating the first control target value of the ratio of the steering angles between the inner front wheel and the rear wheel of the vehicle and the second control target value of the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle; using the vehicle steering angle as the steering angles of the inner rear wheel and the outer rear wheel of the vehicle, and respectively adjusting the steering angles of the inner front wheel and the outer front wheel of the vehicle according to the first control target value and the second control target value, so that the ratio of the steering angles between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle is equal to the second target value.

[0048] The relationship between the vehicle steering angle, vehicle wheelbase, and turning radius of the inner front wheel of the vehicle is expressed as:

[0049] tanδ = L / R

[0050] where δ is the vehicle steering angle, L is the vehicle wheelbase, and R is the turning radius of the inner front wheel of the vehicle.

[0051] The method for calculating the turning radius of the inner front wheel of the vehicle is:

[0052]

[0053]

[0054] r 内 = r 外

[0055] Where ω0 is the vehicle turning angular velocity, R 内 is the turning radius of the inner rear wheel of the vehicle, R 外 is the turning radius of the outer rear wheel of the vehicle; v 内 , v 外 are the axial speeds of the inner and outer wheels respectively, r 内 , r 外 are the radii of the inner and outer wheels respectively, D is the wheelbase of the vehicle, L is the wheelbase of the vehicle, ω 内 is the rotational speed of the inner wheel, ω 外 is the rotational speed of the outer wheel, and all can be obtained by measurement;

[0056] By combining, we get:

[0057]

[0058] The solution is:

[0059]

[0060] The numerical value of the turning radius of the inner front wheel of the vehicle is calculated.

[0061] The calculation methods of the first control target value and the second control target value are:

[0062] The rotational speeds of the inner front wheel and the rear wheel of the vehicle are expressed as:

[0063]

[0064]

[0065] Let the instantaneous center of speed during vehicle turning after adjustment be O', the steering angle after adjustment be β, the turning radius of the inner front wheel of the vehicle after adjustment be R', and the turning radius of the inner rear wheel of the vehicle after adjustment be R 内 ', then we have:

[0066] sinβ = L / R'

[0067] tanβ = L / R 内 '

[0068]

[0069] Where ω 内前 is the rotational speed of the inner front wheel of the vehicle, ω 内后 is the rotational speed of the inner rear wheel of the vehicle, v内前 is the speed of the inner front wheel of the vehicle, v 内后 is the speed of the inner rear wheel of the vehicle, r 内前 is the radius of the inner front wheel of the vehicle, r 内后 is the radius of the inner rear wheel of the vehicle, r 内前 = r 内后 ;

[0070] Simplification gives:

[0071]

[0072] Calculate the first control target value K1;

[0073] Similarly, we have:

[0074]

[0075] where ω 外前 is the rotational speed of the outer front wheel of the vehicle, ω 外后 is the rotational speed of the outer rear wheel of the vehicle, r 外前 is the radius of the outer front wheel of the vehicle, r 外后 is the radius of the outer rear wheel of the vehicle, r 外前 = r 外后 ;

[0076] Simplification gives:

[0077]

[0078] Calculate the second control target value K2.

[0079] The vehicle's inner and outer wheels are respectively controlled by braking through the Electronic Stability Control (ESC) system.

[0080] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0081] Safety benefits: The present invention, especially a vehicle steering control method for a parking system, can ensure a smaller turning radius during parking control in various environmental conditions, guaranteeing scene universality and thus ensuring driving safety.

[0082] Economic benefits: Without adding other equipment, the present invention completes the scheme design based on a vehicle steering control method for a parking system, saving costs.

[0083] Enterprise benefits: The present invention is simple and practical, applicable to all vehicle models, and can interact with rear-wheel steering systems of various models, operating modularly. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 is a schematic flow diagram of an embodiment of the present invention;

[0085] Figure 2 Schematic diagram of the process comparison between the embodiment of the present invention and the existing parking system;

[0086] Figure 3 Schematic diagram of the connection structure of the embodiment of the present invention applied to a vehicle;

[0087] Figure 4 Schematic diagram of the vehicle steering angle model based on wheel speed in the embodiment of the present invention;

[0088] Figure 5 Schematic diagram of adjusting the steering angle of the inner front wheel of the vehicle in the embodiment of the present invention. Detailed implementation manners

[0089] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, 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 herein are only used to explain the present invention and are not used 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.

[0090] The technical solution of the present invention is as follows:

[0091] Embodiment 1:

[0092] As Figure 1 shown, a vehicle steering control method based on a parking system includes the following steps:

[0093] According to the vehicle steering parameters, establish a vehicle steering angle model based on wheel speed; as Figure 4 shown, the vehicle steering parameters at least include the instantaneous center of speed O when the vehicle turns, the wheelbase L of the vehicle, the track width D of the vehicle, the inner wheel radius r 内 , the outer wheel radius r 外 , the inner wheel rotational speed ω 内 , the outer wheel rotational speed ω 外 , the inner wheel axle center speed v 内 and the outer wheel axle center speed v 外 ;

[0094] According to the vehicle steering angle model, calculate the relationship between the inner wheel rotational speed, the outer wheel rotational speed and the turning radius R of the inner front wheel of the vehicle and the wheel track width to obtain the turning radius R of the inner front wheel of the vehicle, and calculate the relationship between the vehicle steering angle δ and the vehicle wheelbase and the turning radius R of the inner front wheel of the vehicle to obtain the vehicle steering angle δ;

[0095] Perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the ratio of the steering angles between the inner front wheel and the rear wheel of the vehicle and the second control target value of the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle;

[0096] Take the vehicle steering angle as the steering angles of the inner rear wheel and the outer rear wheel of the vehicle (since the orientation of the vehicle's rear wheels is always the same as the vehicle's orientation, the steering angles of the inner rear wheel and the outer rear wheel of the vehicle can be understood as the included angle between the vehicle's orientation after steering and the vehicle's orientation before steering. Similarly, the control of the steering angle of the vehicle's front wheels is also carried out based on the definition of the included angle between the vehicle's orientation after steering and the vehicle's orientation before steering). Adjust the steering angles of the inner front wheel and the outer front wheel of the vehicle according to the first control target value and the second control target value respectively, so that the ratio of the steering angle between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angle between the outer front wheel and the rear wheel of the vehicle is equal to the second target value.

[0097] The relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the inner front wheel of the vehicle is expressed as:

[0098] tanδ = L / R

[0099] Where δ is the vehicle steering angle, L is the vehicle wheelbase, and R is the turning radius of the inner front wheel of the vehicle. Under normal circumstances, this steering angle δ is theoretically basically the same as (or in a specific proportional relationship with) the steering angle controlled by the EPS steering controller and the steering wheel end. In the existing project, the parking system controls the steering controller and the steering angle at the steering wheel end to achieve the control target. However, in the present invention, since the solved vehicle steering angle δ is not equal to the steering angle controlled by the steering controller and the steering wheel end under certain conditions, the control target of the present invention is δ 请求 (i.e., β), and the subsequent braking and steering systems make δ approach δ by adjusting the wheel speed relationship 请求 to achieve the control purpose.

[0100] The method for calculating the turning radius of the inner front wheel of the vehicle is:

[0101]

[0102]

[0103] r 内 = r 外

[0104] Where ω0 is the vehicle turning angular velocity, R 内 is the turning radius of the inner rear wheel of the vehicle, R 外 is the turning radius of the outer rear wheel of the vehicle; v 内 and v 外 are the axial velocities of the inner wheel and the outer wheel respectively, r 内 and r 外 are the radii of the inner wheel and the outer wheel respectively, D is the vehicle track width, L is the vehicle wheelbase, ω 内 is the rotational speed of the inner wheel, ω 外 is the rotational speed of the outer wheel, and all can be obtained by measurement;

[0105] Simultaneous equations yield:

[0106]

[0107] The solution is:

[0108]

[0109] The turning radius value of the inner front wheel of the vehicle is calculated.

[0110] Analyzing the front and rear wheels on one side of the vehicle separately, in the existing parking system, the rear wheels move completely following the front wheels, that is, the motion relationship between the front wheels and the rear wheels is a fixed geometric relationship.

[0111] Therefore, when the present invention is not used, the turning radius of the vehicle is completely positively correlated with the front wheel steering angle

[0112] That is

[0113] However, in the present invention, it is necessary to control the front and rear wheels for braking at the same time. It is necessary to control the target β to be less than the front wheel steering angle δ, so as to achieve the purpose of reducing the radius in the same scenario (that is, when δ is the same) of the present invention.

[0114] The calculation methods of the first control target value and the second control target value are as follows:

[0115] The rotational speeds of the inner front wheel and the rear wheel of the vehicle are expressed as:

[0116]

[0117]

[0118] As Figure 5 shown, let the instantaneous center of speed of the vehicle during turning after adjustment be O', the steering angle after adjustment be β, the turning radius of the inner front wheel of the vehicle after adjustment be R', and the turning radius of the inner rear wheel of the vehicle after adjustment be R 内 ', then there are:

[0119] sinβ = L / R'

[0120] tanβ = L / R 内 '

[0121]

[0122] Among them, ω 内前 is the rotational speed of the inner front wheel of the vehicle, ω 内后 is the rotational speed of the inner rear wheel of the vehicle, v 内前 is the speed of the inner front wheel of the vehicle, v 内后 is the speed of the inner rear wheel of the vehicle, r 内前 is the radius of the inner front wheel of the vehicle, r内后 is the radius of the inner rear wheel of the vehicle, r 内前 = r 内后 ;

[0123] Simplification results in:

[0124]

[0125] Calculate the first control target value K1;

[0126] Similarly:

[0127]

[0128] where ω 外前 is the rotational speed of the outer front wheel of the vehicle, ω 外后 is the rotational speed of the outer rear wheel of the vehicle, r 外前 is the radius of the outer front wheel of the vehicle, r 外后 is the radius of the outer rear wheel of the vehicle, r 外前 = r 外后 ;

[0129] Simplification results in:

[0130]

[0131] Calculate the second control target value K2.

[0132] The Electronic Stability Control (ESC) system of the vehicle performs braking control on the inner and outer wheels of the vehicle respectively.

[0133] Embodiment 2:

[0134] A control system is also provided, as shown in Figure 3 and includes:

[0135] A sensor group for collecting vehicle steering parameters, where the vehicle steering parameters at least include the instantaneous center of speed, wheelbase, vehicle track, inner wheel radius, outer wheel radius, inner wheel rotational speed, outer wheel rotational speed, inner wheel axle center speed, and outer wheel axle center speed when the vehicle is turning;

[0136] A parking system for calculating the vehicle steering angle based on the relationship between the vehicle steering angle, vehicle wheelbase, and the turning radius of the inner front wheel of the vehicle;

[0137] The central controller is used to establish a vehicle steering angle model based on wheel speed according to the vehicle steering parameters; calculate the relationship between the inner wheel speed, the outer wheel speed and the turning radius of the inner front wheel of the vehicle and the wheel track according to the vehicle steering angle model to obtain the turning radius of the inner front wheel of the vehicle; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate a first control target value of the steering angle ratio between the inner front wheel and the rear wheel of the vehicle and a second control target value of the steering angle ratio between the outer front wheel and the rear wheel of the vehicle; use the vehicle steering angle as the steering angle of the inner rear wheel and the outer rear wheel of the vehicle, and adjust the steering angles of the inner and outer front wheels of the vehicle according to the first control target value and the second control target value respectively, so that the adjusted steering angle ratio between the inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angle between the outer front wheel and the rear wheel of the vehicle is equal to the second target value.

[0138] The relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the vehicle's inner front wheel is expressed as:

[0139] tanδ=L / R

[0140] Where δ is the vehicle steering angle, L is the vehicle wheelbase, and R is the turning radius of the vehicle's inner front wheel.

[0141] The method for calculating the turning radius of the vehicle's inner front wheel is:

[0142]

[0143]

[0144] r 内 =r 外

[0145] Where ω0 is the vehicle turning angular velocity, R 内 is the turning radius of the inner rear wheel of the vehicle, R 外 is the turning radius of the vehicle's outer rear wheel; r 内 、r 外 are the radii of the inner and outer wheels respectively, D is the vehicle wheelbase, L is the vehicle wheelbase, ω 内 is the inner wheel speed, ω 外 is the outer wheel speed, which can be obtained by measurement;

[0146] Combined, we get:

[0147]

[0148] Solved:

[0149]

[0150] Calculate the turning radius of the vehicle's inner front wheel.

[0151] The calculation methods for the first control target value and the second control target value are as follows:

[0152] The rotational speeds of the inner front wheel and the inner rear wheel of the vehicle are expressed as:

[0153]

[0154]

[0155] Let the instantaneous center of speed of the vehicle during turning after adjustment be O’, the steering angle after adjustment be β, the turning radius of the inner front wheel of the vehicle after adjustment be R', and the turning radius of the inner rear wheel of the vehicle after adjustment be R 内 ', then:

[0156] sinβ = L / R'

[0157] tanβ = L / R 内 '

[0158]

[0159] where ω 内前 is the rotational speed of the inner front wheel of the vehicle, ω 内后 is the rotational speed of the inner rear wheel of the vehicle, v 内前 is the speed of the inner front wheel of the vehicle, v 内后 is the speed of the inner rear wheel of the vehicle, r 内前 is the radius of the inner front wheel of the vehicle, r 内后 is the radius of the inner rear wheel of the vehicle, r 内前 = r 内后 ;

[0160] After simplification:

[0161]

[0162] Calculate the first control target value K1;

[0163] Similarly:

[0164]

[0165] where ω 外前 is the rotational speed of the outer front wheel of the vehicle, ω 外后 is the rotational speed of the outer rear wheel of the vehicle, r 外前 is the radius of the outer front wheel of the vehicle, r 外后 is the radius of the outer rear wheel of the vehicle, r 外前 = r 外后 ;

[0166] After simplification:

[0167]

[0168] The second control target value K2 is calculated.

[0169] The vehicle's inner and outer wheels are respectively braked and controlled by the Electronic Stability Control (ESC) system.

[0170] Its solution consists of a four-wheel steering system that supports the basic structure of the present invention's design, a central parking controller (which stores a vehicle steering control method for a parking system), a CAN bus, an EPS controller, other controllers such as ESC\TCU, and wheel speed sensors, etc.

[0171] The wheel speed sensors provide 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 calculate the vehicle's angular attitude through the wheel speed differences of the four wheels, laying a foundation for further vehicle control.

[0172] The vehicle's CAN bus is used to provide the necessary vehicle signals collected to the central controller for processing by the central controller and to transmit back the control instructions processed by the central controller.

[0173] The central controller is used for: 1) storing and calculating the method of the present invention; 2) storing the angle control calculation module; 3) storing the algorithm of the braking request control module; 4) storing the algorithm programs of normal other functions.

[0174] The EPS controller is used to uniformly execute the angle requests in the present invention.

[0175] The ESC controller is used to complete the automatic requests of the parking system; in the present invention, it is used to distribute different braking forces to the four wheels, ultimately achieving the purpose of coordinated control.

[0176] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vehicle steering control method based on a parking system, characterized in that, Including the following steps: Based on the vehicle steering parameters, establish a vehicle steering angle model based on wheel speed; the vehicle steering parameters at least include the instantaneous center of speed when the vehicle turns, the wheelbase of the vehicle, the track width of the vehicle, the inner wheel radius, the outer wheel radius, the inner wheel speed, the outer wheel speed, the inner wheel axle speed, and the outer wheel axle speed; According to the vehicle steering angle model, calculate the relationship between the inner wheel speed, the outer wheel speed and the turning radius of the inner front wheel of the vehicle and the wheel track width to obtain the turning radius of the inner front wheel of the vehicle, and calculate the vehicle steering angle according to the relationship between the vehicle steering angle and the vehicle wheelbase and the turning radius of the inner front wheel of the vehicle; Perform braking control on the inner and outer wheels of the vehicle respectively, and calculate the first control target value of the ratio of the steering angles between the inner front wheel and the rear wheel of the vehicle and the second control target value of the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle; Use the vehicle steering angle as the steering angles of the inner rear wheel and the outer rear wheel of the vehicle, and respectively adjust the steering angles of the inner front wheel and the outer front wheel of the vehicle according to the first control target value and the second control target value, so that the ratio of the steering angles between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the ratio of the steering angles between the outer front wheel and the rear wheel of the vehicle is equal to the second target value; The relationship between the vehicle steering angle, the vehicle wheelbase, and the turning radius of the inner front wheel of the vehicle is expressed as: tanδ = L / R Where, δ is the vehicle steering angle, L is the vehicle wheelbase, and R is the turning radius of the inner front wheel of the vehicle; The method for calculating the turning radius of the inner front wheel of the vehicle is: r 内 ＝r 外 where ω0 is the vehicle turning angular velocity, R 内 is the turning radius of the inner rear wheel of the vehicle, R 外 is the turning radius of the outer rear wheel of the vehicle; v 内 and v 外 are the axial speeds of the inner and outer wheels respectively, r 内 and r 外 are the radii of the inner and outer wheels respectively, D is the vehicle track width, L is the vehicle wheelbase, ω 内 is the rotational speed of the inner wheel, ω 外 is the rotational speed of the outer wheel, all of which can be obtained through measurement; Simultaneously obtain: Solve to get: Calculate the numerical value of the turning radius of the inner front wheel of the vehicle; The calculation methods of the first control target value and the second control target value are: Express the speeds of the inner front wheel and the rear wheel of the vehicle as: Let the instantaneous center of the vehicle's speed during turning after adjustment be O', the steering angle after adjustment be β, the turning radius of the inner front wheel of the vehicle after adjustment be R', and the turning radius of the inner rear wheel of the vehicle after adjustment be R 内 ', then we have: sinβ = L / R' tanβ = L / R 内 ′ where ω 内前 is the rotational speed of the inner front wheel of the vehicle, ω 内后 is the rotational speed of the inner rear wheel of the vehicle, v 内前 is the speed of the inner front wheel of the vehicle, v 内后 is the speed of the inner rear wheel of the vehicle, r 内前 is the radius of the inner front wheel of the vehicle, r 内后 is the radius of the inner rear wheel of the vehicle, r 内前 = r 内后 ; Simplify to get: Calculate the first control target value K1; Similarly: where ω 外前 is the rotational speed of the outer front wheel of the vehicle, ω 外后 is the rotational speed of the outer rear wheel of the vehicle, r 外前 is the radius of the outer front wheel of the vehicle, r 外后 is the radius of the outer rear wheel of the vehicle, r 外前 = r 外后 ; Simplify to get: Calculate the second control target value K2.

2. The vehicle steering control method based on a parking system according to claim 1, wherein Perform braking control on the inner and outer wheels of the vehicle respectively through the Electronic Stability Control (ESC) system of the vehicle body.

3. A control system using a vehicle steering control method based on a parking system as described in claim 1, characterized in that, Including: A sensor group for collecting vehicle steering parameters, and the vehicle steering parameters at least include the instantaneous center of speed when the vehicle turns, the wheelbase of the vehicle, the average steering angle of the vehicle, the track width of the vehicle, the inner wheel radius, the outer wheel radius, the inner wheel speed, the outer wheel speed, the inner wheel axle speed, and the outer wheel axle speed; A parking system for calculating the vehicle steering angle according to the relationship between the vehicle steering angle and the vehicle wheelbase and the turning radius of the inner front wheel of the vehicle; A central controller, which is used to establish a vehicle steering angle model based on wheel speed according to vehicle steering parameters; calculate 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 according to the vehicle steering angle model to obtain the turning radius of the inner front wheel of the vehicle; perform braking control on the inner and outer wheels of the vehicle respectively, and calculate a first control target value of the steering angle ratio between the inner front wheel and the rear wheel of the vehicle and a second control target value of the steering angle ratio between the outer front wheel and the rear wheel of the vehicle; use the vehicle steering angle as the steering angles of the inner rear wheel and the outer rear wheel of the vehicle, and respectively adjust the steering angles of the inner front wheel and the outer front wheel of the vehicle according to the first control target value and the second control target value, so that the steering angle ratio between the adjusted inner front wheel and the rear wheel of the vehicle is equal to the first control target value and the steering angle ratio between the outer front wheel and the rear wheel of the vehicle is equal to the second target value.

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