Steering control device of autonomous vehicle, autonomous vehicle having the same and steering control method of autonomous vehicle

A steering control device of an autonomous vehicle, the device comprising:

• a waypoint selection unit for selecting a tracking waypoint of an autonomous vehicle based on a current position of the autonomous vehicle with using received waypoints;
• a computation unit for calculating a second heading angle of the autonomous vehicle toward the tracking waypoint based on the position of the autonomous vehicle, and computing a rotation radius of the autonomous vehicle with respect to the tracking waypoint;
• and
• a steering command generation unit for calculating a yaw rate based on a speed of the autonomous vehicle and the computed rotation radius, generating a steering command for controlling the autonomous vehicle corresponding to the calculated yaw rate, and compensating for the steering command based on the second heading angle, and a first heading angle of the autonomous vehicle with respect to north,
• wherein the steering command is generated by a preset characteristic formula that has the form output=f(θ′), where θ′ is the calculated yaw rate and output is the steering command;
• wherein the characteristic formula comprises a polynomial expression and has a single independent variable and a single dependent variable that functionally relate to a value of the steering command and a value of the calculated yaw rate;
• and
• wherein the polynomial expression has at least one coefficient and the coefficient is calculated based on output yaw rates measured on a road surface with respect to additional steering commands.

An autonomous vehicle, comprising:

• a body configured to autonomously move and mounted with a driving means;
• a receiver for receiving a position of the body, a first heading angle of the body with respect to north, and waypoints;
• a steering control device for selecting one of the waypoints as a tracking waypoint based on the position of the body, and generating a steering command such that the body tracks the tracking waypoint;
• and
• a driving controller for receiving the steering command, and controlling the driving means according to the received steering command,
• wherein the steering control device calculates a second heading angle of the autonomous vehicle toward the tracking waypoint based on the position of the autonomous vehicle, and computes a rotation radius of the autonomous vehicle,
• wherein the steering control device calculates a yaw rate based on a speed of the autonomous vehicle and the computed rotation radius, and generates a steering command for controlling the autonomous vehicle corresponding to the calculated yaw rate,
• wherein the steering control device compensates for the generated steering command based on the first and second heading angles, and
• wherein the steering command is generated by a preset characteristic formula that has the form output=f(θ′), where θ′ is the calculated yaw rate and output is the steering command;
• wherein the characteristic formula comprises a polynomial expression and has a single independent variable and a single dependent variable that functionally relate to a value of the steering command and a value of the calculated yaw rate;
• and
• wherein the polynomial expression has at least one coefficient and the coefficient is calculated based on output yaw rates measured on a road surface with respect to additional steering commands.