KR102614555B1 - Autonomous vehicle and steering control method thereof - Google Patents

Abstract

Autonomous vehicles are launched. The autonomous vehicle includes a braking device that controls braking of the vehicle, a steering device that controls steering of the vehicle, and a processor, and the processor determines the maximum side slip angle of the tire in a linear relationship with the lateral force acting on the tire of the vehicle. Determine the maximum speed of the vehicle according to the maximum side slip angle and the curvature of the vehicle's movement path, control the braking device so that the vehicle turns at a speed within the maximum speed, and determine the turning speed of the vehicle and the current position of the vehicle. And, according to the target point of the movement path, the steering angle of the vehicle is determined by considering the slip angle of the tires, and the steering device is controlled so that the vehicle turns at the steering angle.

Description

Autonomous vehicle and its steering control method {AUTONOMOUS VEHICLE AND STEERING CONTROL METHOD THEREOF}

The present disclosure relates to an autonomous vehicle and a method of controlling its steering, and more specifically, to an autonomous vehicle and a method of controlling its steering whose steering is more precisely controlled by taking into account side slip of tires.

Autonomous vehicles estimate the current vehicle location and speed and create a travel path through recognition and judgment algorithms. Specifically, the Pure Pursuit steering control algorithm checks the current vehicle location and driving path and then sets a target point on the moving path. Afterwards, the autonomous vehicle is steered according to the steering angle calculated based on the set target point and vehicle location information.

When a vehicle turns on a curved path, side slip may occur due to turning force acting on the tires. Meanwhile, the pure track steering control algorithm is based on a kinematic bicycle model that does not consider the side slip angle of the tire. Accordingly, when a conventional autonomous vehicle turns, the heading and traveling direction of the tires change as tire slip occurs, resulting in a problem in which the vehicle cannot accurately follow the intended path.

The present disclosure is in response to the above-described need, and the purpose of the present disclosure is to provide an autonomous vehicle whose steering is more precisely controlled in consideration of side slip of tires and a steering control method thereof.

An autonomous vehicle according to an embodiment of the present disclosure includes a braking device that controls braking of the vehicle, a steering device that controls steering of the vehicle, and a processor, wherein the processor calculates a lateral force acting on the tires of the vehicle. Determine the maximum side slip angle of the tire in a linear relationship with the tire, determine the maximum speed of the vehicle according to the maximum side slip angle and the curvature of the moving path of the vehicle, and determine the maximum speed of the vehicle at a speed within the maximum speed. Control the braking device to turn, determine the steering angle of the vehicle by considering the slip angle of the tire according to the turning speed of the vehicle, the current position of the vehicle, and the target point of the movement path, and determine the steering angle of the vehicle so that the vehicle is adjusted to the steering angle. The steering device can be controlled to turn.

The maximum side slip angle may be within 2 degrees.

The processor can determine the maximum speed using the following equation.

here, is the maximum speed, is the maximum side slip angle, is the cornering stiffness coefficient of the front or rear wheels, is the length between the front and rear wheels, is the length between the vehicle's center of gravity and the front or rear wheels, is the mass of the vehicle, is the curvature of the movement path.

The processor can determine the steering angle using the following equation.

here, is the steering angle, is the length between the front and rear wheels, is the angle between the vehicle body direction and the target point direction, is the length between the vehicle's center of gravity and the rear wheels, is the length between the vehicle's center of gravity and the front wheels, is the mass of the vehicle, is the current speed of the vehicle, is the curvature of the movement path, is the cornering stiffness coefficient of the rear wheel, is the distance between the vehicle and the target point, is the cornering stiffness coefficient of the front wheel.

The processor may determine the search distance according to the current speed of the vehicle and the maximum deceleration of the vehicle, and determine the maximum speed according to the maximum curvature of the movement path within the search distance.

The processor can determine the search distance using the following equation.

here, is the search distance, is the current speed of the vehicle, is the maximum deceleration of the vehicle.

A steering control method for an autonomous vehicle according to an embodiment of the present disclosure includes determining a maximum side slip angle of the tire in a linear relationship with a lateral force acting on the tire of the vehicle, the maximum side slip angle and the vehicle Determining the maximum speed of the vehicle according to the curvature of the movement path, controlling the braking device of the vehicle so that the vehicle turns at a speed within the maximum speed, and the turning speed of the vehicle, the current location of the vehicle, and It may include determining a steering angle of the vehicle in consideration of a slip angle of the tire according to the target point of the movement path, and controlling a steering device of the vehicle so that the vehicle turns at the steering angle.

The steering control method of the autonomous vehicle further includes, before controlling the braking device, determining a search distance according to the current speed of the vehicle and the maximum deceleration of the vehicle, where the maximum speed is, It may be determined according to the maximum curvature of the movement path within the search distance.

1 is a block diagram for explaining an autonomous vehicle according to an embodiment of the present disclosure.
Figure 2 is a schematic diagram showing the forces acting on a turning autonomous vehicle.
Figure 3 is a graph showing the relationship between side slip angle and lateral force.
Figure 4 is a schematic diagram for explaining the steering angle of a vehicle to reach a target point on a movement path.
FIG. 5 is a flowchart illustrating a steering control method of an autonomous vehicle according to an embodiment of the present disclosure.

The embodiments described below are shown as examples to aid understanding of the present disclosure, and it should be understood that the present disclosure can be implemented with various modifications, different from the embodiments described herein. However, in describing the present disclosure below, if it is determined that detailed descriptions of related known functions or components may unnecessarily obscure the gist of the present disclosure, the detailed descriptions and specific illustrations will be omitted. Additionally, in order to facilitate understanding of the disclosure, the attached drawings are not drawn to scale and the dimensions of some components may be exaggerated.

The terms used in this specification and claims are general terms selected in consideration of the function of the present disclosure. However, these terms may vary depending on the intention of technicians working in the field, legal or technical interpretation, and the emergence of new technologies. Additionally, some terms are arbitrarily selected by the applicant. These terms may be interpreted as defined in this specification, and if there is no specific term definition, they may be interpreted based on the overall content of this specification and common technical knowledge in the relevant technical field.

In this specification, expressions such as “have,” “may have,” “includes,” or “may include” refer to the presence of the corresponding feature (e.g., component such as numerical value, function, operation, or part). , and does not rule out the existence of additional features.

In addition, since this specification describes the components necessary for explaining each embodiment of the present disclosure, it is not necessarily limited thereto. Accordingly, some components may be changed or omitted, and other components may be added. Additionally, it may be distributed and deployed in different independent devices.

Furthermore, embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present disclosure is not limited or limited by the embodiments.

Hereinafter, the present disclosure will be described in more detail with reference to the attached drawings.

1 is a block diagram for explaining an autonomous vehicle according to an embodiment of the present disclosure.

Referring to FIG. 1, an autonomous vehicle 1 according to an embodiment of the present disclosure includes a braking device 10, a steering device 20, a position determination unit 30, a path creation unit 40, and a processor 100. ) may include.

The braking device 10 can control braking of the vehicle 1. The braking device 10 may be an engine device or a motor driven by electrical energy.

The braking device 10 may control braking of the vehicle 1 so that the vehicle 1 moves at a specific speed. The braking device 10 may receive a speed value from the processor 100 and control braking of the vehicle 1 based on the received speed value.

The steering device 20 can control the steering of the vehicle 1. The steering device 20 may be a steering wheel provided in the vehicle 1.

The steering device 20 can control the steering angle of the vehicle 1 so that the vehicle 1 turns in a specific direction. The steering device 20 may receive the steering angle value from the processor 100 and control the steering of the vehicle 1 based on the received steering angle value.

The location determination unit 30 may determine the current location of the vehicle 1 and transmit the current location information of the vehicle 1 to the processor 100 . The location determination unit 30 may include, but is not limited to, a GPS sensor.

The route generator 40 may generate an autonomous driving route based on road environment information of the vehicle 1 and the current location information of the vehicle 1 and transmit the generated autonomous driving route information to the processor 100 .

The processor 100 may control the braking device 10 and the steering device 20 based on information received from the position determination unit 30 and the path creation unit 40. Accordingly, the vehicle 1 can autonomously drive along the path generated by the path creation unit 40.

That is, the processor 100 according to an embodiment of the present disclosure can determine the speed and steering angle of the vehicle 1 by considering the side slip of the tires. Accordingly, the autonomous vehicle 1 can precisely move along the path created by the path creation unit 40 without deviating from the path. How the processor 100 considers tire side slip will be described in detail later with reference to FIG. 2 and below.

Figure 2 is a schematic diagram showing the forces acting on a turning autonomous vehicle. Figure 3 is a graph showing the relationship between side slip angle and lateral force.

Referring to FIG. 2, the turning vehicle 1 can be schematically represented using a dynamic planar bicycle model. The tires of the vehicle 1 may be composed of front wheels (FT) and rear wheels (RT).

The front wheels (FT) and rear wheels (RT) of the turning vehicle (1) may each receive a lateral force. Accordingly, since side slip occurs at the front wheels (FT) and rear wheels (RT), the directions of the speed vector and heading vector of the front wheels (FT) and rear wheels (RT) may be different by the slip angle.

Referring to FIG. 2, the turning vehicle 1 may have lateral and longitudinal forces acting on the front wheel center (A) and rear wheel center (B), and this can be calculated using the Newton-Euler method as follows: It can be expressed as two mathematical equations. Specifically, Equation 1 is the force equation in the Y-axis direction acting on the vehicle (1), and Equation 2 is the force equation in the Z-axis direction acting on the vehicle (1) based on the center of gravity (C) of the vehicle (1). This is the torque equation.

<Equation 1>

<Equation 2>

here, is the mass of the vehicle, is the acceleration in the Y-axis direction of the vehicle, is the lateral force acting on the rear wheel, is the longitudinal force acting on the front wheel, is the steering angle, is the lateral force acting on the front wheel, is the yaw rate of the vehicle, is the speed of the vehicle in the X-axis direction, is the moment of inertia at the vehicle's center of gravity, is the yaw acceleration of the vehicle, is the length between the center of gravity of the vehicle and the front wheels, refers to the length between the vehicle's center of gravity and the rear wheels.

In addition, assuming a steady state of the turning vehicle 1, the vehicle 1 moves along an arc-shaped path at a constant speed, , , The value of is 0, Can be expressed as Equation 3 below: Equation 3 is an equation showing the relationship between the yaw angular speed of the vehicle 1 turning and moving at a constant speed along a circular path with a predetermined curvature and the speed in the tangential direction of the circular path.

<Equation 3>

here, is the yaw rate of the vehicle, is the curvature of the path, means the speed of the vehicle in the X-axis direction.

Accordingly, Equations 1 and 2, which are the equations of motion of the turning vehicle 1, can be expressed as the following Equations 4 and 5, respectively, under steady state and conditions where the steering angle is sufficiently small.

<Equation 4>

<Equation 5>

here, is the mass of the vehicle, is the speed of the vehicle in the X-axis direction, is the curvature of the path, is the lateral force acting on the rear wheel, is the lateral force acting on the front wheel, is the length between the center of gravity of the vehicle and the front wheels, refers to the length between the vehicle's center of gravity and the rear wheels.

Meanwhile, referring to the graph of FIG. 3, the relationship between the lateral force acting on the tire and the slip angle may be linearly proportional in an area where the slip angle is sufficiently small. That is, when the slip angle is within the linear section (LR), the relationship between lateral force and slip can be expressed by the following equation.

<Equation 6>

<Equation 7>

here, is the lateral force acting on the front wheel, is the cornering stiffness coefficient of the front wheel, is the side slip angle of the front wheel, is the lateral force acting on the rear wheel, is the cornering stiffness coefficient of the rear wheel, is the side slip angle of the rear wheel.

Accordingly, by substituting Equations 6 and 7 into Equations 4 and 5, the side slip angle of the front wheel (FT) and the side slip angle of the rear wheel (RT) can be expressed by the following equations.

<Equation 8>

<Equation 9>

here, is the side slip angle of the front wheel, is the length between the center of gravity of the vehicle and the front wheels, is the mass of the vehicle, is the speed of the vehicle in the X-axis direction, is the curvature of the path, is the cornering stiffness coefficient of the front wheel, is the length between the front and rear wheels, is the side slip angle of the rear wheel, is the length between the vehicle's center of gravity and the rear wheels, is the cornering stiffness coefficient of the rear wheel.

The processor 100 of the present application can determine the maximum side slip angle of the tire of the vehicle 1, which is in a linear relationship with the lateral force acting on the tire. The maximum side slip angle can be within 2 degrees. The maximum side slip angle may be any value within the linear section (LR) in which the lateral force and slip angle have a linear relationship.

The processor 100 of the present application can determine the maximum speed of the vehicle 1 at which the front wheels (FT) and rear wheels (RT) slip by the maximum side slip angle.

That is, the processor 100 determines the maximum speed of the vehicle 1 according to the maximum side slip angle and the curvature of the movement path of the vehicle 1, and uses a braking device (braking device) to allow the vehicle 1 to turn at a speed within the maximum speed. 10) can be controlled.

Meanwhile, depending on the relationship between the side slip angle of the front wheels (FT) and the side slip angle of the rear wheels (RT), the state of the vehicle 1 can be divided into an understeer state and an oversteer state.

Specifically, if the side slip angle of the front wheels (FT) is greater than the side slip angle of the rear wheels (RT), the vehicle 1 is in an understeer state, and the side slip angle of the front wheels (FT) is greater than the side slip angle of the rear wheels (RT). If it is less than this, the vehicle 1 may be in an oversteer state.

When the vehicle (1) is in an understeer state, the maximum speed of the vehicle (1) at which the side slip angle of the front wheel (FT) becomes the maximum side slip angle can be expressed as the following equation using Equation 8: there is.

<Equation 10>

here, is the maximum speed of the vehicle at which the side slip angle of the front wheels becomes the maximum side slip angle, is the maximum side slip angle.

When the vehicle 1 is in an oversteer state, the maximum speed of the vehicle 1 at which the side slip angle of the rear wheel (RT) becomes the maximum side slip angle can be expressed by the following equation.

<Equation 11>

here, is the maximum speed of the vehicle at which the side slip angle of the rear wheels becomes the maximum side slip angle, is the maximum side slip angle.

That is, in the understeer or oversteer state of the vehicle 1, the maximum speed of the vehicle 1 at which the side slip angle of the front wheels (FT) or rear wheels (RT) becomes the maximum side slip angle is expressed as Equations 10 and 11. By combining them into one mathematical equation, they can be expressed as follows.

<Equation 12>

here, is the maximum speed, is the maximum side slip angle, is the cornering stiffness coefficient of the front or rear wheels, is the length between the front and rear wheels, is the length between the vehicle's center of gravity and the front or rear wheels, is the mass of the vehicle, is the curvature of the movement path.

The processor 100 can determine the maximum speed of the vehicle 1 according to Equation 12 and control the braking device 10 so that the vehicle 1 turns at a speed within the maximum speed. For example, the processor 100 may control the braking device 10 so that the vehicle 1 turns at a speed of 80% of the maximum speed.

Accordingly, since the vehicle 1 turns at a speed within the maximum speed, the slip angle of the front wheels (FT) and rear wheels (RT) may be limited to a value within the maximum slip angle that is in a linear relationship with the lateral force. Specifically, within the linear section LR where the lateral force and side slip angle have a linear relationship, Equations 6 and 7 hold, so the speed and steering angle of the vehicle 1 can be controlled more precisely.

Meanwhile, the processor 100 may determine the search distance according to the current speed of the vehicle 1 and the maximum deceleration of the vehicle 1, and determine the maximum speed according to the maximum curvature of the movement path within the search distance.

That is, in Equation 12, the curvature May be the maximum curvature of the movement path within the search distance from the current location of the vehicle 1.

The processor can determine the search distance using the following equation.

<Equation 13>

here, is the search distance, is the current speed of the vehicle, is the maximum deceleration of the vehicle.

The search distance in Equation 13 may be the distance that the vehicle 1 moves until it stops when the vehicle 1 moves at a constant deceleration from the current speed to the maximum deceleration speed.

However, the curvature in Equation 12 is not limited to this, and the curvature in Equation 12 may be updated in real time with the curvature of the path at the current point of the vehicle 1.

Figure 4 is a schematic diagram for explaining the steering angle of a vehicle to reach a target point on a movement path.

The processor 100 determines the steering angle of the vehicle 1 according to the turning speed of the vehicle 1, the current position of the vehicle 1, and the target point of the movement path, and the steering device allows the vehicle 1 to turn at the steering angle. (20) can be controlled. Below, it will be described in detail how the steering angle of the vehicle 1 is determined.

Referring to FIG. 4, point O may be the instantaneous rotation center of the turning vehicle 1. Specifically, point O may be the intersection of the vertical line of the speed vector of the front wheel (FT) and the vertical line of the speed vector of the rear wheel (RT).

The processor 100 calculates the steering angle by defining a target point on the path at each moment from the current position of the vehicle 1 according to the Pure Pursuit steering control algorithm. Specifically, the processor 100 may define a target point (D) among the preset movement paths and form a virtual arc path (P) toward the target point (D). At this time, the virtual arc path (P) is centered on the point O, which is the instantaneous rotation center of the vehicle 1, and the target point (D) may be located on the virtual arc. Accordingly, when the vehicle 1 moves along the arc path P, the rear wheel center B of the vehicle 1 can reach the target point D.

At this time, the radius of the arc, the distance between the vehicle (1) and the target point, the angle between the direction of the vehicle body and the direction of the target point, and the length between the center of gravity (C) of the vehicle (1) and the rear wheels (RT) are as follows: It can be expressed in a mathematical formula such as .

<Equation 14>

here, is the instantaneous turning radius of the vehicle, is the angle between the vehicle body direction and the target point direction, is the distance between the vehicle and the target point, is the side slip angle of the rear wheel.

By applying the law of sines to a triangle with the front wheel center (A), rear wheel center (B), and instantaneous rotation center (O) as vertices, the following equation can be derived.

<Equation 14>

here, is the instantaneous turning radius of the vehicle, is the side slip angle of the front wheel, is the steering angle, is the length between the center of gravity of the vehicle and the front wheels, is the length between the vehicle's center of gravity and the rear wheels.

In Equation 14, assuming that the side slip angle is sufficiently small, the steering angle can be expressed by the following equation.

<Equation 15>

By substituting Equations 8, 9, and 14 into Equation 15, the steering angle can be expressed as the following equation.

<Equation 16>

here, is the steering angle, is the length between the front and rear wheels, is the angle between the vehicle body direction and the target point direction, is the length between the vehicle's center of gravity and the rear wheels, is the length between the vehicle's center of gravity and the front wheels, is the mass of the vehicle, is the current speed of the vehicle, is the curvature of the movement path, is the cornering stiffness coefficient of the rear wheel, is the distance between the vehicle and the target point, is the cornering stiffness coefficient of the front wheel.

The processor 100 can determine the steering angle according to Equation 16 and control the steering device 20 so that the vehicle 1 turns at the determined steering angle.

That is, the autonomous vehicle 1 according to an embodiment of the present disclosure determines the steering angle by considering side slip due to the lateral force acting on the tires when turning, so the vehicle 1 does not deviate from the intended path and achieves more precise driving. Steering can be controlled appropriately.

FIG. 5 is a flowchart illustrating a steering control method of an autonomous vehicle according to an embodiment of the present disclosure.

Referring to FIG. 5, the steering control method of the autonomous vehicle 1 according to an embodiment of the present disclosure determines the maximum side slip angle of the tire in a linear relationship with the lateral force acting on the tire of the vehicle 1. In step S10, the maximum speed of the vehicle 1 is determined according to the maximum side slip angle and the curvature of the movement path of the vehicle 1, and the braking device 10 is used to allow the vehicle 1 to turn at a speed within the maximum speed. A step of controlling (S20) and determining the steering angle of the vehicle 1 according to the turning speed of the vehicle 1, the current position of the vehicle 1, and the target point of the movement path, so that the vehicle 1 turns at the steering angle. It may include a step (S30) of controlling the steering device 20 to do so.

In the step S10 of determining the maximum side slip angle of the tire, the maximum side slip angle in a linear relationship with the lateral force acting on the tire of the vehicle 1 can be determined. The maximum side slip angle can be within 2 degrees. The maximum side slip angle may be any value within a linear section (FIG. 3, LR) in which the lateral force and slip angle have a linear relationship.

In the step S20 of controlling the braking device 10 so that the vehicle 1 turns at a speed within the maximum speed, the maximum speed may be determined according to Equation 12. Accordingly, since the vehicle 1 turns at a speed within the maximum speed, the slip angle of the front wheels (FT) and rear wheels (RT) may be limited to a value within the maximum slip angle that is in a linear relationship with the lateral force. Specifically, within the linear section LR where the lateral force and side slip angle have a linear relationship, Equations 6 and 7 hold, so the speed and steering angle of the vehicle 1 can be controlled more precisely.

In the step S30 of controlling the steering device 20 so that the vehicle 1 turns at the steering angle, the steering angle may be determined by Equation 16. Accordingly, the autonomous vehicle 1 determines the steering angle by considering side slip due to the lateral force acting on the tires when turning, so the vehicle 1 does not deviate from the intended path and the steering can be controlled more precisely. .

In addition, the steering control method of the autonomous vehicle 1 determines the search distance according to the current speed of the vehicle 1 and the maximum deceleration of the vehicle 1 before the step (S20) of controlling the braking device 10. A further decision step may be included. At this time, the maximum speed of the vehicle 1 in the step S20 of controlling the braking device 10 may be determined according to the maximum curvature of the movement path within the search distance.

Specifically, the search distance is determined by Equation 13, and the curvature in Equation 12 may be the maximum curvature among the movement paths within the search distance. The search distance in Equation 13 may be the distance that the vehicle 1 moves until it stops when the vehicle 1 moves at a constant deceleration from the current speed to the maximum deceleration speed. However, the curvature in Equation 12 is not limited to this, and the curvature in Equation 12 may be updated in real time with the curvature of the path at the current point of the vehicle 1.

In the above, preferred embodiments of the present disclosure have been shown and described, but the present disclosure is not limited to the specific embodiments described above, and can be used in the technical field to which the disclosure pertains without departing from the gist of the present disclosure as claimed in the claims. Anyone with ordinary knowledge can make various modifications, and such modifications fall within the scope of the claims.

1: Autonomous vehicle 10: Braking device
20: steering device 100: processor
FT: Front wheel RT: Rear wheel
LR: Linear section P: Movement path

Claims (8)

In autonomous vehicles,
A braking device that controls braking of the vehicle;
a steering device that controls steering of the vehicle; and
Including a processor;
The processor,
Determining the maximum side slip angle of the tire, which is in a linear relationship with the lateral force acting on the tire of the vehicle,
The maximum side slip angle, the curvature of the moving path of the vehicle, the cornering stiffness coefficient of the front or rear wheels of the vehicle, the length between the front wheels and the rear wheels, the length between the center of gravity of the vehicle and the front wheels or the rear wheels, and Determining the maximum speed of the vehicle according to the mass of the vehicle, and controlling the braking device so that the vehicle turns at a speed within the maximum speed,
Determining the steering angle of the vehicle in consideration of the slip angle of the tire according to the turning speed of the vehicle, the current location of the vehicle, and the target point of the movement path, and controlling the steering device so that the vehicle turns at the steering angle Autonomous vehicles. According to paragraph 1,
An autonomous vehicle in which the maximum side slip angle is within 2 degrees. According to paragraph 1,
The processor determines the maximum speed according to the following equation.

here, is the maximum speed, is the maximum side slip angle, is the cornering stiffness coefficient of the front or rear wheels, is the length between the front and rear wheels, is the length between the vehicle's center of gravity and the front or rear wheels, is the mass of the vehicle, is the curvature of the movement path. According to paragraph 1,
An autonomous vehicle in which the processor determines the steering angle according to the following equation.

here, is the steering angle, is the length between the front and rear wheels, is the angle between the vehicle body direction and the target point direction, is the length between the vehicle's center of gravity and the rear wheels, is the length between the vehicle's center of gravity and the front wheels, is the mass of the vehicle, is the current speed of the vehicle, is the curvature of the movement path, is the cornering stiffness coefficient of the rear wheel, is the distance between the vehicle and the target point, is the cornering stiffness coefficient of the front wheel. According to paragraph 1,
The processor,
Determine a search distance according to the current speed of the vehicle and the maximum deceleration of the vehicle,
An autonomous vehicle that determines the maximum speed according to the maximum curvature of the movement path within the search distance. According to clause 5,
An autonomous vehicle in which the processor determines the search distance according to the following equation.

here, is the search distance, is the current speed of the vehicle, is the maximum deceleration of the vehicle. In the steering control method of an autonomous vehicle,
determining a maximum side slip angle of the tire, which is linearly related to a lateral force acting on the tire of the vehicle;
The maximum side slip angle, the curvature of the moving path of the vehicle, the cornering stiffness coefficient of the front or rear wheels of the vehicle, the length between the front wheels and the rear wheels, the length between the center of gravity of the vehicle and the front wheels or the rear wheels, and determining a maximum speed of the vehicle according to the mass of the vehicle, and controlling a braking device of the vehicle so that the vehicle turns at a speed within the maximum speed; and
Determine the steering angle of the vehicle by considering the slip angle of the tire according to the turning speed of the vehicle, the current location of the vehicle, and the target point of the movement path, and adjust the steering device of the vehicle so that the vehicle turns at the steering angle. A steering control method for an autonomous vehicle comprising: controlling. In clause 7,
Before controlling the braking device, determining a search distance according to the current speed of the vehicle and the maximum deceleration of the vehicle,
The maximum speed is determined according to the maximum curvature of the movement path within the search distance.

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