waypointInfo

Get waypoint information table

Since R2023a

Syntax

trajectoryInfo = waypointInfo(trajectory)

Description

trajectoryInfo = waypointInfo(trajectory) returns a table of waypoints, times of arrival, and orientations for the polynomial trajectory.

Examples

Generate Trajectory from Piecewise Polynomial Using polynomialTrajectory

Use the minjerkpolytraj function to generate the piecewise polynomial and the time samples for the specified waypoints of a trajectory.

waypoints = [0 20 20 0 0; 0 0 5 5 0; 0 5 10 5 0];
timePoints = cumsum([0 10 1.25*pi 10 1.25*pi]);
numSamples = 100;
[~,~,~,~,pp,~,tsamples] = minjerkpolytraj(waypoints,timePoints,numSamples);

Use the polynomialTrajectory System object to generate a trajectory from the piecewise polynomial that a multirotor must follow. Specify the sample rate of the trajectory and the orientation at each waypoint.

eulerAngles = [0 0 0; 0 0 0; 180 0 0; 180 0 0; 0 0 0];
q = quaternion(eulerAngles,"eulerd","ZYX","frame");
traj = polynomialTrajectory(pp,SampleRate=100,Orientation=q);

Inspect the waypoints, times of arrival, and orientation by using waypointInfo.

waypointInfo(traj)

ans=5×3 table
    TimeOfArrival                   Waypoints                      Orientation   
    _____________    ________________________________________    ________________

            0                 0              0              0    {1x1 quaternion}
           10                20              0              5    {1x1 quaternion}
       13.927                20              5             10    {1x1 quaternion}
       23.927                 0              5              5    {1x1 quaternion}
       27.854        6.9321e-14    -1.0658e-13    -8.9706e-14    {1x1 quaternion}

Obtain 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

Get the yaw angle from the orientation.

eulOrientation = quat2eul(orient);
yawAngle = eulOrientation(:,1);

Plot the generated positions and orientations, as well as the specified waypoints.

plot3(pos(:,1),pos(:,2),pos(:,3), ...
      waypoints(1,:),waypoints(2,:),waypoints(3,:),"--o")
hold on
% Plot the yaw using quiver.
quiverIdx = 1:100:length(pos);
quiver3(pos(quiverIdx,1),pos(quiverIdx,2),pos(quiverIdx,3), ...
        cos(yawAngle(quiverIdx)),sin(yawAngle(quiverIdx)), ...
        zeros(numel(quiverIdx),1))
title("Position")
xlabel("X (m)")
ylabel("Y (m)")
zlabel("Z (m)")
legend({"Position","Waypoints","Orientation"})
axis equal
hold off

Obtain Pose Information of Polynomial Trajectory at Certain Time

Use the minsnappolytraj function to generate the piecewise polynomial and the time samples for the specified waypoints of a trajectory.

waypoints = [0 20 20 0 0; 0 0 5 5 0; 0 5 10 5 0];
timePoints = linspace(0,30,5);
numSamples = 100;
[~,~,~,~,~,pp,~,~] = minsnappolytraj(waypoints,timePoints,numSamples);

Use the polynomialTrajectory System object to generate a trajectory from the piecewise polynomial. Specify the sample rate of the trajectory.

traj = polynomialTrajectory(pp,SampleRate=100);

Inspect the waypoints and times of arrival by using waypointInfo.

waypointInfo(traj)

ans=5×2 table
    TimeOfArrival                   Waypoints                
    _____________    ________________________________________

           0                  0              0              0
         7.5                 20              0              5
          15                 20              5             10
        22.5                  0              5              5
          30         2.4897e-13    -2.7471e-12    -2.6352e-12

Obtain the time of arrival between the second and fourth waypoint. Create timestamps to sample the trajectory.

t0 = traj.TimeOfArrival(2);
tf = traj.TimeOfArrival(4);
sampleTimes = linspace(t0,tf,1000);

Obtain the position, orientation, velocity, and acceleration information at the sampled timestamps using the lookupPose object function.

[pos,orient,vel,accel,~] = lookupPose(traj,sampleTimes);

Get the yaw angle from the orientation.

eulOrientation = quat2eul(orient);
yawAngle = eulOrientation(:,1);

Plot the generated positions and orientations, as well as the specified waypoints.

plot3(pos(:,1),pos(:,2),pos(:,3), ...
      waypoints(1,:),waypoints(2,:),waypoints(3,:),"--o")
hold on
% Plot the yaw using quiver.
quiverIdx = 1:100:length(pos);
quiver3(pos(quiverIdx,1),pos(quiverIdx,2),pos(quiverIdx,3), ...
        cos(yawAngle(quiverIdx)),sin(yawAngle(quiverIdx)), ...
        zeros(numel(quiverIdx),1))
title("Position and Orientation")
xlabel("X (m)")
ylabel("Y (m)")
zlabel("Z (m)")
legend({"Position","Waypoints","Orientation"})
axis equal
hold off

Plot the velocity profiles.

figure
subplot(3,1,1)
plot(sampleTimes,vel(:,1))
title("Velocity Profile")
ylabel("v_x (m/s)")
subplot(3,1,2)
plot(sampleTimes,vel(:,2))
ylabel("v_y (m/s)")
subplot(3,1,3)
plot(sampleTimes,vel(:,3))
ylabel("v_z (m/s)")
xlabel("Time (sec)")

Plot the acceleration profiles.

figure
subplot(3,1,1)
plot(sampleTimes,accel(:,1))
title("Acceleration Profile")
ylabel("a_x (m/s^2)")
subplot(3,1,2)
plot(sampleTimes,accel(:,2))
ylabel("a_y (m/s^2)")
subplot(3,1,3)
plot(sampleTimes,accel(:,3))
ylabel("a_z (m/s^2)")
xlabel("Time (sec)")

Input Arguments

trajectory — Polynomial trajectory

polynomialTrajectory object

Polynomial trajectory, specified as a polynomialTrajectory object.

Output Arguments

trajectoryInfo — Trajectory information

table

Trajectory information, returned as a table with variables corresponding to these properties of trajectory:

• Waypoints

• TimeOfArrival

• Orientation

The trajectory information table always has columns for Waypoints and TimeOfArrival. If you set the Orientation property when constructing,the trajectory information table additionally returns orientation.

Data Types: table

Version History

Introduced in R2023a