Calibration of Multi-LIDAR Systems: Application to Bucket Wheel Reclaimers

This paper presents a method to calibrate the extrinsic parameters of light detection and rangings (LIDARs) mounted on a bucket-wheel reclaimer (BWR). BWR's are widely used for stacking and reclaiming bulk materials in stockyards. Current BWR systems are either manually operated, remotely operated, or semiautomated using the real-time point cloud data generated by one or more LIDARs. The accurate calibration is of crucial importance as the accuracy of the earth frame point cloud data depends on it. The automated calibration is also a prerequisite for fully autonomous BWR control. The calibration of BWR systems is more difficult than many other LIDAR systems because of their limited pose variation capabilities and the environmental constraints of stockyards. This paper analyzes the problem, presents observability conditions, presents a method to estimate the calibration parameters, and discusses the challenges involved with BWR systems. The results demonstrate subdecimeter accuracy.