98 lines
3.8 KiB
Matlab
98 lines
3.8 KiB
Matlab
clc
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clear all
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close all
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import gtsam.*;
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deltaT = 0.001;
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timeElapsed = 1;
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times = 0:deltaT:timeElapsed;
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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disp('--------------------------------------------------------');
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disp('Integration in body frame VS integration in navigation frame');
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disp('TOY EXAMPLE:');
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disp('- Body moves along a circular trajectory with constant rotation rate -omega- and constant -velocity- (in the body frame)');
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disp('- We compare two integration schemes: integating in the navigation frame (similar to Lupton approach) VS integrating in the body frame')
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disp('- Navigation frame is assumed inertial for simplicity')
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omega = [0;0;2*pi];
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velocity = [1;0;0];
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%% Set initial conditions for the true trajectory and for the estimates
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% (one estimate is obtained by integrating in the body frame, the other
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% by integrating in the navigation frame)
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% Initial state (body)
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currentPoseGlobal = Pose3;
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currentVelocityGlobal = velocity;
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% Initial state estimate (integrating in navigation frame)
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currentPoseGlobalIMUnav = currentPoseGlobal;
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currentVelocityGlobalIMUnav = currentVelocityGlobal;
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% Initial state estimate (integrating in the body frame)
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currentPoseGlobalIMUbody = currentPoseGlobal;
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currentVelocityGlobalIMUbody = currentVelocityGlobal;
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%% Prepare data structures for actual trajectory and estimates
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% Actual trajectory
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positions = zeros(3, length(times)+1);
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positions(:,1) = currentPoseGlobal.translation;
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poses(1).p = positions(:,1);
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poses(1).R = currentPoseGlobal.rotation.matrix;
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% Trajectory estimate (integrated in the navigation frame)
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positionsIMUnav = zeros(3, length(times)+1);
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positionsIMUnav(:,1) = currentPoseGlobalIMUbody.translation;
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posesIMUnav(1).p = positionsIMUnav(:,1);
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posesIMUnav(1).R = poses(1).R;
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% Trajectory estimate (integrated in the body frame)
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positionsIMUbody = zeros(3, length(times)+1);
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positionsIMUbody(:,1) = currentPoseGlobalIMUbody.translation;
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posesIMUbody(1).p = positionsIMUbody(:,1);
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posesIMUbody(1).R = poses(1).R;
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%% Main loop
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i = 2;
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for t = times
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%% Create the actual trajectory, using the velocities and
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% accelerations in the inertial frame to compute the positions
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[ currentPoseGlobal, currentVelocityGlobal ] = imuSimulator.integrateTrajectory( ...
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currentPoseGlobal, omega, velocity, velocity, deltaT);
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%% Simulate IMU measurements, considering Coriolis effect
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% (in this simple example we neglect gravity and there are no other forces acting on the body)
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acc_omega = imuSimulator.calculateIMUMeas_coriolis( ...
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omega, omega, velocity, velocity, deltaT);
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%% Integrate in the body frame
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[ currentPoseGlobalIMUbody, currentVelocityGlobalIMUbody ] = imuSimulator.integrateIMUTrajectory_bodyFrame( ...
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currentPoseGlobalIMUbody, currentVelocityGlobalIMUbody, acc_omega, deltaT, velocity);
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%% Integrate in the navigation frame
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[ currentPoseGlobalIMUnav, currentVelocityGlobalIMUnav ] = imuSimulator.integrateIMUTrajectory_navFrame( ...
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currentPoseGlobalIMUnav, currentVelocityGlobalIMUnav, acc_omega, deltaT);
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%% Store data in some structure for statistics and plots
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positions(:,i) = currentPoseGlobal.translation;
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positionsIMUbody(:,i) = currentPoseGlobalIMUbody.translation;
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positionsIMUnav(:,i) = currentPoseGlobalIMUnav.translation;
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% -
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poses(i).p = positions(:,i);
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posesIMUbody(i).p = positionsIMUbody(:,i);
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posesIMUnav(i).p = positionsIMUnav(:,i);
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% -
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poses(i).R = currentPoseGlobal.rotation.matrix;
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posesIMUbody(i).R = currentPoseGlobalIMUbody.rotation.matrix;
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posesIMUnav(i).R = currentPoseGlobalIMUnav.rotation.matrix;
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i = i + 1;
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end
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figure(1)
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hold on;
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plot(positions(1,:), positions(2,:), '-b');
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plot(positionsIMUbody(1,:), positionsIMUbody(2,:), '-r');
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plot(positionsIMUnav(1,:), positionsIMUnav(2,:), ':k');
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axis equal;
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legend('true trajectory', 'traj integrated in body', 'traj integrated in nav')
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