lookupPose

Obtain pose of geodetic trajectory for a certain time

Since R2021a

Syntax

[position,orientation,velocity,acceleration,angularVelocity,ecef2ref] = lookupPose(traj,sampleTimes)

[___] = lookupPose(traj,sampleTimes,coordinateSystem)

Description

[position,orientation,velocity,acceleration,angularVelocity,ecef2ref] = 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.

[___] = lookupPose(traj,sampleTimes,coordinateSystem) additionally enables you to specify the format of the position output.

Examples

Create geoTrajectory and Look Up Pose

Create a geoTrajectory with starting LLA at [15 15 0] and ending LLA at [75 75 100]. Set the flight time to ten hours. Sample the trajectory every 1000 seconds.

startLLA = [15 15 0];
endLLA = [75 75 100];
timeOfTravel = [0 3600*10];
sampleRate  = 0.001;

trajectory = geoTrajectory([startLLA;endLLA],timeOfTravel,'SampleRate',sampleRate);

Output the LLA waypoints of the trajectory.

positionsLLA = startLLA;
while ~isDone(trajectory)
    positionsLLA = [positionsLLA;trajectory()];  
end
positionsLLA

positionsLLA = 37×3

   15.0000   15.0000         0
   16.6667   16.6667    2.7778
   18.3333   18.3333    5.5556
   20.0000   20.0000    8.3333
   21.6667   21.6667   11.1111
   23.3333   23.3333   13.8889
   25.0000   25.0000   16.6667
   26.6667   26.6667   19.4444
   28.3333   28.3333   22.2222
   30.0000   30.0000   25.0000
      ⋮

Look up the Cartesian waypoints of the trajectory in the ECEF frame by using the lookupPose function.

sampleTimes = 0:1000:3600*10;
n = length(sampleTimes);
positionsCart = lookupPose(trajectory,sampleTimes,'ECEF');

Visualize the results in the ECEF frame.

figure()
km = 1000;
plot3(positionsCart(1,1)/km,positionsCart(1,2)/km,positionsCart(1,3)/km, 'b*');
hold on;
plot3(positionsCart(end,1)/km,positionsCart(end,2)/km,positionsCart(end,3)/km, 'bo');
plot3(positionsCart(:,1)/km,positionsCart(:,2)/km,positionsCart(:,3)/km,'b');

plot3([0 positionsCart(1,1)]/km,[0 positionsCart(1,2)]/km,[0 positionsCart(1,3)]/km,'k:');
plot3([0 positionsCart(end,1)]/km,[0 positionsCart(end,2)]/km,[0 positionsCart(end,3)]/km,'k:');
xlabel('x (km)'); ylabel('y (km)'); zlabel('z (km)');
legend('Start position','End position', 'Trajectory')

Input Arguments

traj — Geodetic trajectory

geoTrajectory object

Geodetic trajectory, specified as a geoTrajectory object.

sampleTimes — Sample times

K-element vector of nonnegative scalar

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

coordinateSystem — Coordinate system to report positions

'LLA' (default) | 'ECEF'

Coordinate system to report positions, specified as:

• 'LLA' — Report positions as latitude in degrees, longitude in degrees, and altitude above the WGS84 reference ellipsoid in meters.

• 'ECEF' — Report positions as Cartesian coordinates in the ECEF (Earth-Centered-Earth-Fixed) coordinate frame in meters.

.

Output Arguments

position — Positions in local reference coordinate system (deg deg m)

K-by-3 matrix

Geodetic positions in local reference coordinate system, returned as a K-by-3 matrix. K is the number of SampleTimes.

• When the coordinateSystem input is specified as 'LLA', the three elements in each row represent the latitude in degrees, longitude in degrees, and altitude above the WGS84 reference ellipsoid in meters of the geodetic waypoint.

• When the coordinateSystem input is specified as 'ECEF', the three elements in each row represent the Cartesian position coordinates in the ECEF (Earth-Centered-Earth-Fixed) coordinate frame in meters.

Data Types: double

orientation — Orientation in local reference coordinate system

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

Orientation in the local reference coordinate system, returned as a K-by-1 quaternion column vector or as a 3-by-3-by-K real array in which each 3-by-3 matrix is a rotation matrix.

Each quaternion or rotation matrix is a frame rotation from the local reference frame (NED or ENU) at the waypoint to the body frame of the target on the trajectory.

K is the number of SampleTimes.

Data Types: double

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

K-by-3 matrix

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

K is specified by the SamplesPerFrame property.

Data Types: double

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

K-by-3 matrix

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

K is the number of SampleTimes.

Data Types: double

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

K-by-3 matrix

Angular velocity in the local reference coordinate system in radians per second, returned as a K-by-3 matrix.

K is the number of SampleTimes.

Data Types: double

ecef2ref — Orientation of reference frame with respect to ECEF frame

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

Orientation of the reference frame with respect to the ECEF (Earth-Centered-Earth-Fixed) frame, returned as a K-by-1 quaternion column vector or as a 3-by-3-by-K real array, in which each 3-by-3 matrix is a rotation matrix.

Each quaternion or 3-by-3 rotation matrix is a frame rotation from the ECEF frame to the local reference frame (NED or ENU) at the current trajectory position.

K is the number of SampleTimes.

Data Types: double

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2021a