lookupPose

Obtain pose information for certain time

Since R2020b

Syntax

[position,orientation,velocity,acceleration,angularVelocity] = lookupPose(traj,sampleTimes)

Description

[position,orientation,velocity,acceleration,angularVelocity] = lookupPose(traj,sampleTimes) returns the pose information of the waypoint trajectory at the specified sample times. If any sample time is beyond the duration of the trajectory, the corresponding pose information is returned as NaN.

Examples

Create Trajectory Using Waypoints and Ground Speed

Create a waypointTrajectory object that connects two waypoints. The velocity of the trajectory at the two waypoints is 0 $\mathrm{m}/\mathrm{s}$ and 10 $\mathrm{m}/\mathrm{s}$, respectively. Restrict the jerk limit to 0.5 $\mathrm{m}/{\mathrm{s}}^3$ to enable the trapezoidal acceleration profile.

waypoints = [0  0  0;
            10 50 10];
speeds = [0 10];
jerkLimit = 0.5;
trajectory = waypointTrajectory(waypoints,GroundSpeed=speeds,JerkLimit=jerkLimit);

Obtain the initial time and final time of the trajectory by querying the TimeOfArrival property. Create time stamps to sample the trajectory.

t0 = trajectory.TimeOfArrival(1);
tf = trajectory.TimeOfArrival(end);
sampleTimes = linspace(t0,tf,100);

Obtain the position, velocity, and acceleration information at these sampled time stamps using the lookupPose object function.

[position,~,velocity,acceleration,~] = lookupPose(trajectory,sampleTimes);

Plot the trajectory.

figure()
plot3(position(:,1),position(:,2),position(:,3))
xlabel("x (m)")
ylabel("y (m)")
zlabel("z (m)")
title("Trajectory")

Plot the velocity profile.

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

Plot the acceleration profile. From the results, the acceleration profile of the planar motion is trapezoidal.

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

Input Arguments

traj — Waypoint trajectory

waypointTrajectory object

Waypoint trajectory, specified as a waypointTrajectory object.

sampleTimes — Sample times

M-element vector of nonnegative scalar

Sample times in seconds, specified as an M-element vector of nonnegative scalars.

Output Arguments

position — Position in local navigation coordinate system (m)

M-by-3 matrix

Position in the local navigation coordinate system in meters, returned as an M-by-3 matrix.

M is specified by the sampleTimes input.

Data Types: double

orientation — Orientation in local navigation coordinate system

M-element quaternion column vector | 3-by-3-by-M real array

Orientation in the local navigation coordinate system, returned as an M-by-1 quaternion column vector or a 3-by-3-by-M real array.

Each quaternion or 3-by-3 rotation matrix is a frame rotation from the local navigation coordinate system to the current body coordinate system.

M is specified by the sampleTimes input.

Data Types: double

velocity — Velocity in local navigation coordinate system (m/s)

M-by-3 matrix

Velocity in the local navigation coordinate system in meters per second, returned as an M-by-3 matrix.

M is specified by the sampleTimes input.

Data Types: double

acceleration — Acceleration in local navigation coordinate system (m/s²)

M-by-3 matrix

Acceleration in the local navigation coordinate system in meters per second squared, returned as an M-by-3 matrix.

M is specified by the sampleTimes input.

Data Types: double

angularVelocity — Angular velocity in local navigation coordinate system (rad/s)

M-by-3 matrix

Angular velocity in the local navigation coordinate system in radians per second, returned as an M-by-3 matrix.

M is specified by the sampleTimes input.

Data Types: double

Version History

Introduced in R2020b