Question about discrete model in fast lio about fast_lio HOT 9 CLOSED

Thanks for your interests. You are right. Fastlio1 uses the zero order discretion，Fastlio2 uses the first order model. But they are really very similar since the imu sample time is always very tiny.

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Thanks for your interests. You are right. Fastlio1 uses the zero order discretion，Fastlio2 uses the first order model. But they are really very similar since the imu sample time is always very tiny.

Thanks! And I have another question about the computation of mattix F_x and F_w in appendix A. Are there some materials describing specific process?

from fast_lio.

Thanks for your interests. You are right. Fastlio1 uses the zero order discretion，Fastlio2 uses the first order model. But they are really very similar since the imu sample time is always very tiny.

Thanks! And I have another question about the computation of mattix F_x and F_w in appendix A. Are there some materials describing specific process?

I think the computation of the F_x and F_w would be very easy, if you regard appendix A as a simple chain-rule of partial differential. And IKFOM's appendix A&B has a simple example for the computation of chain-rule of partial differential combining the boxplus operation, may help you.

from fast_lio.

Thanks for your interests. You are right. Fastlio1 uses the zero order discretion，Fastlio2 uses the first order model. But they are really very similar since the imu sample time is always very tiny.

Thanks! And I have another question about the computation of mattix F_x and F_w in appendix A. Are there some materials describing specific process?

I think the computation of the F_x and F_w would be very easy, if you regard appendix A as a simple chain-rule of partial differential. And IKFOM's appendix A&B has a simple example for the computation of chain-rule of partial differential combining the boxplus operation, may help you.

Thanks!

from fast_lio.

@XW-HKU hi, I wonder what the difference about matrix F_x and F_w between fast lio and Quaternion kinematics for the error-state KF. I try to compare them. And some parts sre same, some parts are different.

from fast_lio.

@XW-HKU hi, I wonder what the difference about matrix F_x and F_w between fast lio and Quaternion kinematics for the error-state KF. I try to compare them. And some parts sre same, some parts are different.

The main differences i think is using rotation matrix or quaternion.

from fast_lio.

@XW-HKU hi, I wonder what the difference about matrix F_x and F_w between fast lio and Quaternion kinematics for the error-state KF. I try to compare them. And some parts sre same, some parts are different.

The main differences i think is using rotation matrix or quaternion.

Got it!

from fast_lio.

@XW-HKU hi, I wonder what the difference about matrix F_x and F_w between fast lio and Quaternion kinematics for the error-state KF. I try to compare them. And some parts sre same, some parts are different.

The main differences i think is using rotation matrix or quaternion.

Hi, Mr. Xu, there is a very good blog about ESKF deduction based on SO3, which is written by Dr. Gao, Xiang. Based on his deduction, there should be no "-A(w_ideltaT)^TdeltaT" for equation 7 in your 2021 RAL fastlio paper.

What do you think?

from fast_lio.

@XW-HKU hi, I wonder what the difference about matrix F_x and F_w between fast lio and Quaternion kinematics for the error-state KF. I try to compare them. And some parts sre same, some parts are different.

The main differences i think is using rotation matrix or quaternion.

Hi, Mr. Xu, there is a very good blog about ESKF deduction based on SO3, which is written by Dr. Gao, Xiang. Based on his deduction, there should be no "-A(w_i_deltaT)^T_deltaT" for equation 7 in your 2021 RAL fastlio paper. What do you think?

I'm also curious that it's not in the code, but it's in the paper.Again, i should be clear about the formula.

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