To provide a measurement and control system that measures the profile of logs moving on a conveyer belt in a sawmill and controls the saw blade positioning system so that the highest priced combination of planks is cut from the log. One or two planks can be cut from a single log

A line-drawing laser is used to draw a line across the log. A video camera positioned above the log, captures Images of the line as the log passes the camera. The positioning of the camera, the laser and the log is such that the height profile of the log appears as a curve on the video images.

A National Instruments frame-grabber card acquires images from the video camera. An Addi-Data Digital input/output card provides an isolated 24volt interface with the saw controls and log detectors.

The program, written in LabView â, using IMAQ Visionâ performs the following functions:

• Set-up and calibration.
• Entry of standard plank sizes and values.
• Image acquisition.
• High-speed image analysis to extract height profiles.
• Analysis of all height profiles along the length of the log to determine the optimum combination of plank sizes and lengths that can be extracted.
• Saw positioning control outputs