diff --git a/matlab/gtsam_examples/IMUKittiExample.m b/matlab/gtsam_examples/IMUKittiExample.m new file mode 100644 index 000000000..4f995b7b9 --- /dev/null +++ b/matlab/gtsam_examples/IMUKittiExample.m @@ -0,0 +1,165 @@ +close all +clc + +import gtsam.*; + +IMU_data = dmlread('IMU.txt'); +VO_data = dmlread('VO.txt'); +GPS_data = dmlread('GPS.txt'); + +SummaryTemplate = gtsam.ImuFactorPreintegratedMeasurements( ... + gtsam.imuBias.ConstantBias([0;0;0], [0;0;0]), ... + 1e-3 * eye(3), 1e-3 * eye(3), 1e-3 * eye(3)); + +%% Set initial conditions for the estimated trajectory +disp('TODO: we have GPS so this initialization is not right') +currentPoseGlobal = Pose3; % initial pose is the reference frame (navigation frame) +currentVelocityGlobal = [0;0;0]; % the vehicle is stationary at the beginning +bias_acc = [0;0;0]; % we initialize accelerometer biases to zero +bias_omega = [0;0;0]; % we initialize gyro biases to zero + +%% Solver object +isamParams = ISAM2Params; +isamParams.setRelinearizeSkip(1); +isam = gtsam.ISAM2(isamParams); + +%% create nonlinear factor graph +factors = NonlinearFactorGraph; +values = Values; + +%% Create prior on initial pose, velocity, and biases +sigma_init_x = 1.0 +sigma_init_v = 1.0 +sigma_init_b = 1.0 + +values.insert(symbol('x',0), currentPoseGlobal); +values.insert(symbol('v',0), LieVector(currentVelocityGlobal) ); +values.insert(symbol('b',0), imuBias.ConstantBias(bias_acc,bias_omega) ); + +% Prior on initial pose +factors.add(PriorFactorPose3(symbol('x',0), ... + currentPoseGlobal, noiseModel.Isotropic.Sigma(6, sigma_init_x))); +% Prior on initial velocity +factors.add(PriorFactorLieVector(symbol('v',0), ... + LieVector(currentVelocityGlobal), noiseModel.Isotropic.Sigma(3, sigma_init_v))); +% Prior on initial bias +factors.add(PriorFactorConstantBias(symbol('b',0), ... + imuBias.ConstantBias(bias_acc,bias_omega), noiseModel.Isotropic.Sigma(6, sigma_init_b))); + +%% Main loop: +% (1) we read the measurements +% (2) we create the corresponding factors in the graph +% (3) we solve the graph to obtain and optimal estimate of robot trajectory + +i = 2; +lastTime = 0; +lastIndex = 0; +currentSummarizedMeasurement = ImuFactorPreintegratedMeasurements(summaryTemplate); + +times = sort([VO_data(:,1); GPS_data(:,1)]); % this are the time-stamps at which we want to initialize a new node in the graph +IMU_times = IMU_data(:,1); + +disp('TODO: still needed to take care of the initial time') + +for t = times + % At each non=IMU measurement we initialize a new node in the graph + currentIndex = find( times == t ); + currentPoseKey = symbol('x',currentIndex); + currentVelKey = symbol('v',currentIndex); + currentBiasKey = symbol('b',currentIndex); + + %% add preintegrated IMU factor between previous state and current state + % ======================================================================= + IMUbetweenTimesIndices = find( IMU_times>+t_previous & IMU_times<= t); + % all imu measurements occurred between t_previous and t + + % we assume that each row of the IMU.txt file has the following structure: + % timestamp delta_t acc_x acc_y acc_z omega_x omega_y omega_z + disp('TODO: We want don t want to preintegrate with zero bias, but to use the most recent estimate') + currentSummarizedMeasurement = ImuFactorPreintegratedMeasurements(summaryTemplate); + for i=1:length(IMUbetweenTimesIndices) + index = IMUbetweenTimesIndices(i); % the row of the IMU_data matrix that we have to integrate + deltaT = IMU_data(index,2); + accMeas = IMU_data(index,3:5); + omegaMeas = IMU_data(index,6:8); + % Accumulate preintegrated measurement + currentSummarizedMeasurement.integrateMeasurement(accMeas, omegaMeas, deltaT); + end + + disp('TODO: is the imu noise right?') + % Create IMU factor + factors.add(ImuFactor( ... + previousPoseKey, previousVelKey, ... + currentPoseKey, currentVelKey, ... + currentBiasKey, currentSummarizedMeasurement, g, cor_v, ... + noiseModel.Isotropic.Sigma(9, 1e-6))); + % ======================================================================= + + + %% add factor corresponding to GPS measurements (if available at the current time) + % ======================================================================= + if isempty( find(GPS_data(:,1) == t ) ) == 0 % it is a GPS measurement + if length( find(GPS_data(:,1)) ) > 1 + error('more GPS measurements at the same time stamp: it should be an error') + end + + index = find(GPS_data(:,1) == t ); % the row of the IMU_data matrix that we have to integrate + GPSmeas = GPS_data(index,2:4); + + noiseModelGPS = ???; % noiseModelGPS.Isotropic.Sigma(6, sigma_init_x)) + + % add factor + disp('TODO: is the GPS noise right?') + factors.add(PriorFactor???(currentPoseKey, GPSmeas, noiseModelGPS) ); + end + % ======================================================================= + + + %% add factor corresponding to VO measurements (if available at the current time) + % ======================================================================= + if isempty( find(VO_data(:,1) == t ) )== 0 % it is a GPS measurement + if length( find(VO_data(:,1)) ) > 1 + error('more VO measurements at the same time stamp: it should be an error') + end + + index = find( VO_data(:,1) == t ); % the row of the IMU_data matrix that we have to integrate + VOmeas_pos = VO_data(index,2:4)'; + VOmeas_ang = VO_data(index,5:7)'; + + VOpose = Pose3( Rot3(VOmeas_ang) , Point3(VOmeas_pos) ); + noiseModelVO = ???; % noiseModelGPS.Isotropic.Sigma(6, sigma_init_x)) + + % add factor + disp('TODO: is the VO noise right?') + factors.add(BetweenFactorPose3(lastVOPoseKey, currentPoseKey, VOpose, noiseModelVO)); + + lastVOPoseKey = currentPoseKey; + end + % ======================================================================= + + disp('TODO: add values') + % values.insert(, initialPose); + % values.insert(symbol('v',lastIndex+1), initialVel); + + %% Update solver + % ======================================================================= + isam.update(factors, values); + factors = NonlinearFactorGraph; + values = Values; + + isam.calculateEstimate(currentPoseKey); + % M = isam.marginalCovariance(key_pose); + % ======================================================================= + + previousPoseKey = currentPoseKey; + previousVelKey = currentVelKey; + t_previous = t; +end + +disp('TODO: display results') +% figure(1) +% hold on; +% plot(positions(1,:), positions(2,:), '-b'); +% plot3DTrajectory(isam.calculateEstimate, 'g-'); +% axis equal; +% legend('true trajectory', 'traj integrated in body', 'traj integrated in nav')