Hi Juliette,
There is an example in the help for waypointTrajectory, but it is not on the documentation page. I have created a request to add this example to the documentation page. For now, you can access this example by executing the following command on the Command Window:
help waypointTrajectory
The example is:
% EXAMPLE 2: Generate a racetrack trajectory by specifying the velocity
% and orientation at each waypoint.
Fs = 100;
wps = [0 0 0;
20 0 0;
20 5 0;
0 5 0;
0 0 0];
t = cumsum([0 10 1.25*pi 10 1.25*pi]).';
vels = [2 0 0;
2 0 0;
-2 0 0;
-2 0 0;
2 0 0];
eulerAngs = [0 0 0;
0 0 0;
180 0 0;
180 0 0;
0 0 0];
q = quaternion(eulerAngs, 'eulerd', 'ZYX', 'frame');
traj = waypointTrajectory(wps, 'SampleRate', Fs, ...
'TimeOfArrival', t, 'Velocities', vels, 'Orientation', q);
% fetch pose information one buffer frame at a time
[pos, orient, vel, acc, angvel] = traj();
i = 1;
spf = traj.SamplesPerFrame;
while ~isDone(traj)
idx = (i+1):(i+spf);
[pos(idx,:), orient(idx,:), ...
vel(idx,:), acc(idx,:), angvel(idx,:)] = traj();
i = i+spf;
end
% Plot generated positions and specified waypoints.
plot(pos(:,1),pos(:,2), wps(:,1),wps(:,2), '--o')
title('Position')
xlabel('X (m)')
ylabel('Y (m)')
zlabel('Z (m)')
legend({'Position', 'Waypoints'})
axis equal
The Velocities property is the velocity of the object at the time is passes the corresponding waypoint, not the velocity as the object travels from waypoint to waypoint. These Velocities values, along with the Waypoints and TimeOfArrival values, determine the object's speed from waypoint to waypoint.
The Algorithms section of the documentation page also has some more details on how the trajectory is generated.
Thanks,
Ryan
