Lumber surface profiling independent of bulk motion

A novel method is described to measure surface height profiles of lumber boards while they travel along a conveyor in a sawmill. Both surfaces of the board are identified independently, even on non-ideal conveyors where there are lateral motions relative to the sensors. Separate surface measurements are very useful for product quality control because each side of a piece of lumber is typically cut by a different tool. Therefore, such measurements open important new opportunities for machine fault diagnosis. The surface height profile measurement method uses multiple sequential sensors and a mathematical method based on linear inverse theory to separate surface profile information from lateral motions. The method was implemented using industrial-style laser sensors, and was effective both in the laboratory and in tests on the cant line of a large sawmill cutting dimension lumber.