6F Calibration for Lidar and IMU

[Anonymous]

Hey Ryan,

I wonder how you conducted the 6-DOF extrinsic calibration for Lidar and IMU. Thanks a lot.

Michael

[Ryan B]

Hi, Michael.

The lever-arm offsets between the origin of the IMU frame and the origin of the lidar sensor frame are estimated based on the frame definitions provided within the documentation for each sensor and the high-precision 3D model of the CNC machined aluminum case. The lever-arm offsets between the phase centers of the GNSS antennas and the origin of the IMU frame are estimated using a laboratory calibration procedure (as described in section 12.9 of the hardware documentation, https://www.openmms.org/wp-content/uploads/html/openmms_hardware.html#calibrating-the-gnss-lever-arms). In an effort to simplify this calibration procedure for OpenMMS v1.3 hardware, an MS Excel workbook is provided that contains the embedded calculations for estimating the offsets based on the observations made during the procedure.

The boresight angles between the IMU frame and the lidar sensor frame are estimated using an in-situ procedure based on manually identifying planar surfaces in areas of the collected point cloud that were observed within overlapping flight lines (as described in section 2.6 of the software documentation, https://www.openmms.org/wp-content/uploads/html/openmms_software.html#lidar-sensor-boresight-calibration). The calibration procedure utilizes a parametric least-squares optimization of the RMSE for the planar surfaces to estimate the boresight angles.

These procedures have been tailored specifically to the OpenMMS project and therefore a bit of work would be required in order to generalize them for other mobile mapping sensors.

Hope this helps,
Ryan

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