Automatic landing method of a reclaimer on the stockpile

Large excavation reclaimers are used to dig ore and transfer it to the blast furnaces that refine the ore into pure metal form. The reclaiming job consists of two operations: (1) landing a reclaimer bucket on the surface of a pile and (2) slewing its boom with rotating buckets to scoop the ore. An automatic landing method for choosing where to dig in a pile of raw ore is proposed to achieve autonomous reclaiming. The method comprises detecting the shape of a pile, extracting contour lines of the pile, obtaining the joint angles of the reclaimer and determining an optimal landing point. A 3D range finder was developed with laser radar concepts to detect the shape and height of the ore pile. A series of image processing techniques for extracting the contour line from the 3D range data of a pile is suggested. A height map is obtained from the acquired range data for a pile and a contour map is obtained through image processing steps, including interpolation and edge following. The optimal landing point of the bucket on the contour line is determined so that an overload problem does not occur in the slewing operation and the reclaiming efficiency can be maximized. The algorithm for finding the landing point requires an inverse kinematics solution for the reclaimer. The forward kinematics of the reclaimer is first obtained. A constraint equation based on the geometrical relationship is suggested to solve the inverse kinematics of the reclaimer with redundancy. The proposed method was successfully applied to a working reclaimer. An autonomous reclaimer is now being operated in the yards of Kwangyang Steelworks in Korea