Importance

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Abstract

A target member mounted on a stationary object, such as a pallet, includes at least three reflector elements. An identifying means, such as a high intensity light source, and an imaging sensor are carried by another, movable object, such as a forklift truck. The reflector elements are so configured as to form images of the identifying means with said images defining a plane oriented other than normal to align from the identifying means to that plane, the images also defining a circle that does not include the identifying means. The target member may be in the form of a vertically oriented planar support member on which are mounted a pair of convex mirrors and a concave mirror. The images of the identifying means in the mirrors are detected by an imaging sensor, such as a television camera, and the directions of each of the images at the camera are used to determine all six degrees of positional information of the sensor with respect to the target. That information may be used to guide the forklift truck into position relative to a pallet. The target support member includes retroreflector elements to aid in locating a pallet. Circuit means are provided to flash the light source and in response to the light returned by the retroreflectors to define an area on the image plane of the camera where reflections from the mirrors may be found. Ambient light images are then temporarily recorded, the light source again flashed, and the ambient images are electronically removed so that only those images due to reflections in the mirrors are finally recorded.

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First Claim