Design, development and implementation of a mechatronic log traceability system

This thesis concerns a mechatronic system, designed and developed for the forest industry, to trace logs from forest to sawmill. The research is a key part of a large research project launched by the EU in 2006 called the Indisputable Key project. Wood waste during harvesting, transportation and refinement is a major concern for the wood industry worldwide. Some raw materials are not suited for specific end products, and acknowledging this late in the wood value chain is cost inefficient. Pinpointing specific raw material suitable for a particular end product could increase quality, reduce waste and environmental impact; to accomplish this, traceability is essential. To trace the raw material of a final wood product to its origin, marking and reading of the different specimens must occur at each refining stage in the wood value chain. The traceability chain can be divided into three main stages: forest to sawmill, inside the sawmill, and from sawmill to second manufacturer. The research presented here covers the first part of the wood value chain, namely, forest to sawmill. In Scandinavian countries, logs are cut to length in the forest using a harvester machine. To trace logs, a unique identity code needs to be associated with each log at harvesting time in the forest and detected before further processing at the sawmill. Earlier research using RFID transponders as code carriers have been functionally verified but too costly. Although the cost of RFID transponders is declining, alternative methods are considered a necessity. This constitutes the main driver behind this thesis. The thesis presents a promising alternative log marking method comprising a harvester saw-integrated log code printer and a sawmill code detection system. An identity code in the form of a standard matrix code is applied via the harvester saw bar during cutting. A prototype has been designed and realized and the results point towards a both time and cost efficient solution. The code detection system, to be placed in one or more locations at the sawmill, is based on vision technology and image processing to detect the applied log codes. Both log code marking and reading systems communicate with an ICT system which maintains the traceability database. A major advantage of the system is that both marking and reading is performed without any time-loss and hence do not disturb the high pace production flow in todays forestry. Also, the item cost of each code mark is very low, compared to e.g. a transponder. The marking technology is patent pending. A field test was performed in December 2009 in northern Sweden. A test batch of 320 logs was marked and read. Two code structures (i.e., matrix and barcode) were applied, where 210 barcoded logs were used to demonstrate log traceability between forest and sawmill. This result indicates that this technology has potential. The prototype is not intended for commercial use, but serves merely to demonstrate the potential of the method; further research is needed to improve its functionality.