Motion planning in curvilinear coordinates for autonomous vehicles

An autonomous vehicle, comprising:

• a perception system comprising one or more sensors;
• and
• a computing device comprising a processor and memory containing programming instructions that are configured to cause the computing device to act as a motion planning system by:
• determining a reference curve that represents a path via which the autonomous vehicle may travel in an environment over a time horizon,
• receiving, from the perception system, data representative of an actor that is moving in the environment,
• segmenting the time horizon into a plurality of time intervals, and
• for each of the time intervals:
• define a coarse bounding geometry for the actor over the time interval, wherein the coarse bounding geometry encompasses the actor and includes possible position of the actor during the time interval,
• define a coarse bounding geometry for the autonomous vehicle over the time interval, wherein the coarse bounding geometry encompasses the autonomous vehicle,
• determine whether the coarse bounding geometry for the actor will intersect with the coarse bounding geometry of the autonomous vehicle over a distance interval on the reference curve,
• subdivide the time interval into time subintervals in response to the coarse bounding geometry for the actor intersecting the coarse bounding geometry of the autonomous vehicle,
• determine a plurality of fine bounding geometries for the actor over the time subintervals and a plurality of fine bounding geometries for the autonomous vehicle over distance subintervals, and
• predict a lateral offset distance between the reference curve and the actor based on the plurality of fine bounding geometries of the actor and the plurality of fine bounding geometries of the autonomous vehicle;
• and
• use the predicted lateral offset distances to determine a trajectory for the autonomous vehicle.

A method of planning a trajectory for an autonomous vehicle, the method comprising:

• determining a reference curve that represents a path via which the autonomous vehicle may travel in an environment over a time horizon,
• receiving, from a perception system of the autonomous vehicle, data representative of an actor that is moving in the environment,
• segmenting the time horizon into a plurality of time intervals, and
• for each of the time intervals:
• defining a coarse bounding geometry for the actor over the time interval, wherein the coarse bounding geometry encompasses the actor and includes possible position of the actor during the time interval,
• defining a coarse bounding geometry for the autonomous vehicle over the time interval, wherein the coarse bounding geometry encompasses the autonomous vehicle,
• determining whether the coarse bounding geometry for the actor will intersect with the coarse bounding geometry of the autonomous vehicle over a distance interval on the reference curve,
• subdividing the time interval into time subintervals in response to the coarse bounding geometry for the actor intersecting the coarse bounding geometry of the autonomous vehicle,
• determining a plurality of fine bounding geometries for the actor over the time subintervals and a plurality of fine bounding geometries for the autonomous vehicle over distance subintervals, and
• predict a lateral offset distance between the reference curve and the actor based on the plurality of fine bounding geometries of the actor and the plurality of fine bounding geometries of the autonomous vehicle;
• and
• use the predicted lateral offset distances to determine a trajectory for the autonomous vehicle by:
• determining one or more regions of configuration space for the autonomous vehicle that are occupied and one or more regions of configuration space for the autonomous vehicle that are free;
• and
• determining a planned trajectory that is fully within a region of free configuration space for the autonomous vehicle and outside of all regions of occupied configuration space for the autonomous vehicle.