CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Application No. PCT/CN2019/080070, filed Mar. 28, 2019, entitled “A QP SPLINE PATH AND SPIRAL PATH BASED REFERENCE LINE SMOOTHING METHOD FOR AUTONOMOUS DRIVING,” which is incorporated by reference herein by its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to operating autonomous driving vehicles. More particularly, embodiments of the disclosure relate to smoothing a reference line for operating autonomous driving vehicles.

BACKGROUND

Vehicles operating in an autonomous mode (e.g., driverless) can relieve occupants, especially the driver, from some driving-related responsibilities. When operating in an autonomous mode, the vehicle can navigate to various locations using onboard sensors, allowing the vehicle to travel with minimal human interaction or in some cases without any passengers. Motion planning and control are critical operations in autonomous driving. Particularly, trajectory planning is a critical component in an autonomous driving system. Conventional trajectory planning techniques rely heavily on high-quality reference lines, which are guidance paths, e.g., a center line of a road, for autonomous driving vehicles, to generate stable trajectories.

Reference lines can be generated from map data points, typically a sequence of two-dimensional (2D) points in the world coordinate. Reference lines directly generated from the map data points are raw reference lines, which may lack the required smoothness and therefore can lead to unstable and oscillating trajectories between planning cycles. As such, raw reference lines typically need to be smoothed using various smoothing techniques for better driving experiences.

SUMMARY

In a first aspect, the present disclosure provides a computer-implemented method for operating an autonomous driving vehicle (ADV), the method comprising: in response to receiving an initial reference line representing a route from a first location to a second location associated with an autonomous driving vehicle (ADV), segmenting the initial reference line into a plurality of reference line segments, including a first reference line segment, a second reference segment, and a third reference line segment in sequence; smoothing the first reference line segment and the third reference line segment using a Quadratic programming (QP) spline smoothing algorithm; smoothing the second reference line segment using a spiral smoothing algorithm; and connecting smoothed reference line segments from the plurality of reference line segments to generate a smoothed reference line, which is to be used as a reference line of the route to control the ADV.

In a second aspect, the present disclosure provides a non-transitory machine-readable medium having instructions stored therein for operating an autonomous driving vehicle (ADV), the instructions, when executed by a processor, causing the processor to perform operations, the operations comprising: in response to receiving an initial reference line representing a route from a first location to a second location associated with an autonomous driving vehicle (ADV), segmenting the initial reference line into a plurality of reference line segments, including a first reference line segment, a second reference segment, and a third reference line segment in sequence; smoothing the first reference line segment and the third reference line segment using a Quadratic programming (QP) spline smoothing algorithm; smoothing the second reference line segment using a spiral smoothing algorithm; and connecting smoothed reference line segments from the plurality of reference line segments to generate a smoothed reference line, which is to be used as a reference line of the route to control the ADV.

In a third aspect, the present disclosure provides a data processing system, comprising: a processor; and a memory coupled to the processor to store instructions, which when executed by the processor, cause the processor to perform operations, the operations including: in response to receiving an initial reference line representing a route from a first location to a second location associated with an autonomous driving vehicle (ADV), segmenting the initial reference line into a plurality of reference line segments, including a first reference line segment, a second reference segment, and a third reference line segment in sequence, smoothing the first reference line segment and the third reference line segment using a Quadratic programming (QP) spline smoothing algorithm, smoothing the second reference line segment using a spiral smoothing algorithm, and connecting smoothed reference line segments from the plurality of reference line segments to generate a smoothed reference line, which is to be used as a reference line of the route to control the ADV.

