Scanner system for separate-sided lumber surface measurements

A novel scanner system is presented that is able to separately measure the surface height profile of each side of a piece of lumber while moving longitudinally in a saw mill. Such measurements are very useful for product quality control. In addition, because each side of the lumber is typically cut by a different tool, separate surface measurements allow important new opportunities for machine maintenance and repair diagnostics. The proposed surface measurement method is effective and well suited for industrial use. It takes into account bulk motions of the lumber in the measurement direction, and therefore does not require an ideal straight-line lumber conveyor. The scanner system uses multiple industrial-style laser sensors to make surface height measurements. It then uses a mathematical method based on linear inverse theory to separate surface profile information from the bulk motions that would otherwise contaminate the measurements. The identification of surface profiles is rapid and stable. Several different sensor arrangements can be used, depending on the desired profiling outcome. The range of possible applications is illustrated by four example sensor arrangements. They are: single profiling along one surface, parallel profiling along opposite surfaces (also giving thickness), parallel profiling along the same surface (also giving twist), and parallel profiling on the same and opposite surfaces (also giving thickness, twist, and wedge).

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