The question about using Imu factor when need to update preintegrated measurements with updated bias

[Weitong Wu]

Hello. How should I do to update the preintegrated measurements using updated bias? In examples, it is just showing how to add imu factor and using optimizer. Thanks.

[Weitong Wu]

After reading the GTSAM code about Imu factor like ImuFactor.cpp, ManifoldPreintegration.cpp, etc. I have got the following conclusion:

(1) In optimization, when bias changes, we can update the delta measurments using a first-order expansion like in [1] formula(44)

(2) After optimization,  we can use new bias and recompute the preintegrated imu measurements if bias changes a lot especially in initilaization.

[1] Forster C, Carlone L, Dellaert F, et al. On-Manifold Preintegration for Real-Time Visual--Inertial Odometry[J]. IEEE Transactions on Robotics, 2016, 33(1): 1-21.