Radio frequency scanning technology for estimating lumber strength and locating anomalies in southern pine lumber and poles

The lumber industry lags most other industries in the development and adoption of technologies to automate manufacturing processes. This difficulty in the development of automated systems is largely due to the heterogeneous nature of solid wood. The following document describes research and development of new machine vision technologies that employ radio frequency scanning technology for lumber strength estimation as well as the detection of knots, juvenile wood and decay.; Research estimating strength properties of lumber indicated that, with accurate detection and correction for lumber moisture content, strength of dry southern pine lumber can be estimated by radio frequency scanning with results comparable to those reported for both MSR and x-ray scanning of southern pine.; Research involving knot detection in green and kiln-dried hardwood and softwood lumber indicated that radio frequency signal voltage magnitude and signal phase shift were effective in differentiating knots from clear wood in both green and kiln-dried red oak and southern pine lumber specimens.; Studies to evaluate the potential for juvenile wood identification were also conducted. Although signal attenuation was largely ineffective in differentiating juvenile wood from normal wood, signal phase shift was effective in differentiating juvenile wood for 3 of the 4 frequencies tested in both the parallel- and perpendicular-to-grain electrode configurations.; A pilot study was performed to evaluate the potential for detecting decay in pentachlorophenol-treated power poles. Results indicated that signal attenuation effectively differentiated decayed wood and sound wood in all 5 poles tested at a 5000 kHz frequency. Signal phase shift also successfully identified decayed wood and sound wood in all 5 poles tested at 2000 and 5000 kHz frequencies.