I have used li_calib to calibrate individual LiDAR-IMU pairs on my robotic platform successfully.
However, the sensor configuration I work with features multiple LiDAR sensors (all of them VLP-16 models, compatible with the provided software implementation). I have developed a simple method to interpolate these trajectories at some given timestamps (for visualization and debugging purposes), and I have come across a doubt while doing that.
If we assume that we are using a system with two LiDARs, L1 and L2, and a common IMU, I1, we could generate two IMU-centric trajectories: one through the L1-I1 pair calibration, and another one through the L2-I1 calibration. Then, in li_calib's paper, at the end of section III - Trajectory Representation and Notation, below Equations 6 and 7, one can find the following claim:
[...] As described in the above equations, we set the first IMU frame{I0} as the reference frame for the IMU trajectory, [...]
Thus, I would expect that, given the same set of IMU data (from I1), both LiDAR-IMU trajectories should share a common origin / reference frame. Furthermore, were the LiDAR-IMU calibrations an exact representation of the physical system, the two trajectories would overlap on top of each other.
However, as you can see in the images above, the origin pose of the trajectories produced by the L1-I1 and L2-I1 is not the same. The fact that the trajectories' shape does not coincide is (at least partially) explained by the fact that the L2-I1 calibration in this run was not accurate.
Could you please help me understand if my assumptions are correct? In case they are not, how can I indicate to the TrajectoryEstimator that there is a common sensor (in this case, I1) to constrain the trajectory estimation?
Hello,
I have used
li_calibto calibrate individual LiDAR-IMU pairs on my robotic platform successfully. However, the sensor configuration I work with features multiple LiDAR sensors (all of them VLP-16 models, compatible with the provided software implementation). I have developed a simple method to interpolate these trajectories at some given timestamps (for visualization and debugging purposes), and I have come across a doubt while doing that.If we assume that we are using a system with two LiDARs, L1 and L2, and a common IMU, I1, we could generate two IMU-centric trajectories: one through the L1-I1 pair calibration, and another one through the L2-I1 calibration. Then, in
li_calib's paper, at the end of section III - Trajectory Representation and Notation, below Equations 6 and 7, one can find the following claim:[...] As described in the above equations, we set the first IMU frame{I0} as the reference frame for the IMU trajectory, [...]Thus, I would expect that, given the same set of IMU data (from I1), both LiDAR-IMU trajectories should share a common origin / reference frame. Furthermore, were the LiDAR-IMU calibrations an exact representation of the physical system, the two trajectories would overlap on top of each other.However, as you can see in the images above, the origin pose of the trajectories produced by the L1-I1 and L2-I1 is not the same. The fact that the trajectories' shape does not coincide is (at least partially) explained by the fact that the L2-I1 calibration in this run was not accurate.
Could you please help me understand if my assumptions are correct? In case they are not, how can I indicate to the
TrajectoryEstimatorthat there is a common sensor (in this case, I1) to constrain the trajectory estimation?Thank you for your time.