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hyye / lio-mapping

Implementation of Tightly Coupled 3D Lidar Inertial Odometry and Mapping (LIO-mapping)
https://sites.google.com/view/lio-mapping
GNU General Public License v3.0
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Gravity estimation in initialization #75

Open goldenminerlmg opened 3 years ago

goldenminerlmg commented 3 years ago

@hyye Hi , In the recommend paper ''Monocular Visual–Inertial State Estimation With Online Initialization and Camera–IMU Extrinsic Calibration'' in part V-B, I still confuse how to estimate the gravity? Can you give a detail description for these part: 1)ApproximateGravity(all_laser_transforms, g, transform_lb): tmp_A = 0.5 I3x3 (dt12 dt12 dt23 + dt23 dt23 dt12); tmp_b = (pl2 - pl1) dt23 - (pl3 - pl2) dt12 .+ (rl2 - rl1) plb dt23 - (rl3 - rl2) plb dt12 .+ rl2 rlb dp23 dt12 + rl1 rlb dv12 dt12 dt23 .- rl1 rlb dp12 dt23;

2)RefineGravityAccBias(all_laser_transforms, Vs, Bgs, g, transform_lb, R_WI) tmp_A.block<3, 3>(0, 0) = dt12 Matrix3d::Identity(); tmp_A.block<3, 2>(0, 6) = 0.5 Matrix3d::Identity() lxly dt12 dt12; tmp_b.block<3, 1>(0, 0) = pl2 - pl1 - rl1 rlb dp12 - (rl1 - rl2) plb - 0.5 g_refined dt12 dt12; tmp_A.block<3, 3>(3, 0) = Matrix3d::Identity(); tmp_A.block<3, 3>(3, 3) = -Matrix3d::Identity(); tmp_A.block<3, 2>(3, 6) = Matrix3d::Identity() lxly dt12; tmp_b.block<3, 1>(3, 0) = -rl1 rlb dv12 - g_refined dt12; What's the physical meaning for these fomula? Hope for your answer. Thank you very much!

LeisureLei commented 3 years ago

@hyye Hi , In the recommend paper ''Monocular Visual–Inertial State Estimation With Online Initialization and Camera–IMU Extrinsic Calibration'' in part V-B, I still confuse how to estimate the gravity? Can you give a detail description for these part: 1)ApproximateGravity(all_laser_transforms, g, transform_lb): tmp_A = 0.5 I3x3 (dt12 dt12 dt23 + dt23 dt23 dt12); tmp_b = (pl2 - pl1) dt23 - (pl3 - pl2) dt12 .+ (rl2 - rl1) plb dt23 - (rl3 - rl2) plb dt12 .+ rl2 rlb dp23 dt12 + rl1 rlb dv12 dt12 dt23 .- rl1 rlb dp12 dt23;

2)RefineGravityAccBias(all_laser_transforms, Vs, Bgs, g, transform_lb, R_WI) tmp_A.block<3, 3>(0, 0) = dt12 Matrix3d::Identity(); tmp_A.block<3, 2>(0, 6) = 0.5 Matrix3d::Identity() lxly dt12 dt12; tmp_b.block<3, 1>(0, 0) = pl2 - pl1 - rl1 rlb dp12 - (rl1 - rl2) plb - 0.5 g_refined dt12 dt12; tmp_A.block<3, 3>(3, 0) = Matrix3d::Identity(); tmp_A.block<3, 3>(3, 3) = -Matrix3d::Identity(); tmp_A.block<3, 2>(3, 6) = Matrix3d::Identity() lxly dt12; tmp_b.block<3, 1>(3, 0) = -rl1 rlb dv12 - g_refined dt12; What's the physical meaning for these fomula? Hope for your answer. Thank you very much!

Hi, have you figured out how to estimate gravity? I am confused too.