1. Multiple Lidar Calibration Surface Registration Aras Akbari Dr.Liam Pedersen

2. LER (SEV) System Overview SICK LMS 291 Lidar 70 Hz scan rate 180° range, 0.25° angular resolution Hokuyo UTM-30LX Lidar 45 Hz scan rate 180° range, 0.25° angular resolution

3. Problem Statement Point clouds from different lidars not well aligned using best estimates (digital level)

4. Pos at time t Laser pose WRT Robot Point at time t in lidar fram Optimize Problem Statement

5. Surface Registration ICP: point To point matching Finding the rotation, translation between two point clouds by solving the orientation problem using Horn's quaternion- based method. Result : Reason -> No point to point correspondences.

6. Terrain Problem The Terrains are different. ** * * * * * * ** * * * * ∆t∆t Time difference Pose estimator error

7. Surface Registration Used Nelder Mead method to minimize the Mahalanobis distance between the corresponding points Where is the mean vector and ∑ is the covariance matrix of closets point to x in

8. Solved globally

9. Multiple Lidar Calibration Calibrate lidar’s wrt primary: Pose at time t reference lidar point set (global coords) adjusted lidar points (wrt rover) at time t calibration correction

10. No calibration target required But need some vertical relief.

12. Question ?Question ?? Questions??