Find closest point on reference path to global point
Generate a reference path from a set of waypoints.
waypoints = [0 0; 50 20; 100 0; 150 10]; refPath = referencePathFrenet(waypoints);
Create a trajectoryGeneratorFrenet object from the reference path.
connector = trajectoryGeneratorFrenet(refPath);
Generate a five-second trajectory between the path origin and a point 30 m down the path as Frenet states.
initState = [0 0 0 0 0 0]; % [S dS ddS L dL ddL] termState = [30 0 0 0 0 0]; % [S dS ddS L dL ddL] frenetTraj = connect(connector,initState,termState,5);
Convert the trajectory to the global states.
globalTraj = frenet2global(refPath,frenetTraj.Trajectory);
Display the reference path and the trajectory.
show(refPath); axis equal hold on plot(globalTraj(:,1),globalTraj(:,2),'b')
Specify global points and find the closest points on reference path.
globalPoints = waypoints(2:end,:) + [20 -50]; nearestPathPoint = closestPoint(refPath,globalPoints);
Display the global points and the closest points on reference path.
Interpolate between the arc lengths of the first two closest points along the reference path.
arclengths = linspace(nearestPathPoint(1,6),nearestPathPoint(2,6),10); pathStates = interpolate(refPath,arclengths);
Display the interpolated path points.
plot(pathStates(:,1),pathStates(:,2),'g') legend(["Waypoints","Reference Path","Trajectory to 30m",... "Global Points","Closest Points","Interpolated Path Points"])
refPath— Reference path
Reference path, specified as a
points— Global points
Global points, specified as a P-by-2 numeric matrix with rows of
[x y]. P is the number of points.
Positions are in meters.
pathPoints— Closest points on reference path
Closest points on the reference path , returned as an N-by-6
numeric matrix with rows of form
[x y theta kappa dkappa s], where:
theta— SE(2) state expressed in global
y in meters and
theta in radians
kappa — Curvature, or inverse of the radius, in
dkappa — Derivative of curvature with respect to arc
length in meters per second
s — Arc length, or distance along path from path origin, in
N is the number of points sampled along the reference path.