Reference line smoothing method using piecewise spiral curves with weighted geometry costs

A non-transitory machine-readable medium having instructions stored therein, which when executed by a processor, cause the processor to perform operations, the operations comprising:

• processing map data to generate a plurality of points that define a reference line along an ADV route from a first location to a second location, wherein each point has a two dimensional (2D) coordinate and each consecutive pair of points form a reference line segment along the reference line;
• initializing optimization parameters, wherein the optimization parameters include a length of each reference line segment, a 2D coordinate of each point, a direction of each reference line segment, a curvature of each reference line segment, and a curvature change rate of each reference line segment;
• optimizing the optimization parameters of the route such that
• an output of an objective function is minimized, wherein each reference line segment is defined by a quintic polynomial function and the objective function is based on the quintic polynomial function, and
• a set of constraints associated with the reference line segments are satisfied;
• and
• generating a smooth reference line based on the optimized parameters, wherein the smooth reference line is utilized as a reference to direct the ADV from the first location to the second location.

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
• processing map data to generate a plurality of points that define a reference line along an ADV route from a first location to a second location, wherein each point has a two dimensional (2D) coordinate and each consecutive pair of points form a reference line segment along the reference line;
• initializing optimization parameters, wherein the optimization parameters include one or more of the following:
• a length of each reference line segment, a 2D coordinate of each point, a direction of each reference line segment, a curvature of each reference line segment, and a curvature change rate of each reference line segment;
• optimizing the optimization parameters of the route such that
• an output of an objective function is minimized, and
• a set of constraints associated with the reference line segments are satisfied;
• and
• generating a smooth reference line based on the optimized parameters, wherein the smooth reference line is utilized as a reference to direct the ADV from the first location to the second location.