Patent ID: 7106883

Claim:
A container position detection method, employed in a cargo crane, of stacking a suspended container held by a hoisting accessory on a target container stowed on the ground, and landing the hoisting accessory on the target container or stowing the suspended container on a target position on the ground, the method comprising: an image pickup unit arranging step of arranging an image pickup unit which images the hoisting accessory or the suspended container, and the target container or a target position mark displaying a target position at the same time, at an end on one side of the hoisting accessory; a line detection step of detecting a candidate line group which becomes a candidate for a first line representing an edge of the end of the hoisting accessory or an edge of the end of the suspended container, and for a second line representing an edge of the end of the target container or an edge of the target position mark, by detecting a change in luminance or hue of a pixel group included in the image data, which is obtained by imaging by the image pickup unit, and setting at least a line approximating the arrangement of the pixel group to be included in the candidate line group, which causes a change in luminance or hue larger than a set value; a second line determination step of comparing parallelism and horizontal distance of the candidate line group for the first line, to determine, as the second line, a line having parallelism and horizontal distance of a value within a preset value, of lines included in the candidate line group; and a relative position detection step of detecting a relative position of the target container or the target position mark with respect to the hoisting accessory or the suspended container, from the position of the second line with respect to the first line.