**Author details**

ies case by case and there are different opinions on the price level. The price of the tags de‐ pends greatly on volumes – large scale mass production lowers the unit price considerably. For a hard tag the price may go as low as a few cents if there is market for sufficiently large volumes – large numbers of tags are needed to push the price down but before the prices are

The main challenge in achieving near 100 % identification success rate in RFID based log marking is the application of the tag – the insertion of the transponder into the wood. This has to be done automatically so that the log production efficiency is not significantly re‐ duced by the log marking. Several prototypes of automatic applicators for forestry harvest‐ ers have been developed in different research projects but so far no device suitable for long term production use has been successfully built. This is the main technical challenge to be solved before the RFID based log marking can be adopted in large scale in the forest indus‐ try. Current solution allows manual tag application for small scale (up to a few thousand logs) log marking, e.g. for marking log batches and piles, or test logs for research and testing purposes, or marking tree trunks or logs when trees are felled manually using chain saws.

There are three main types of situations where traceability can be utilized to gain production improvements in forest industry: trouble-shooting, production optimisation and data min‐ ing. Trouble-shooting occurs when some end-product or batch deviates from the target quality. With traceability it is possible to trace the defect of quality to its root cause. For ex‐ ample it could be connected to the specific kiln in the saw mill or to a wood batch and its

Optimisation can be achieved using the traceability information. For example if the spiral grain angle of a log that has been used to produce a board is known, the twist of the board can be estimated. Using this information the board can be placed as a bottom of the drying patch. This can reduce the final twist of these boards by 50%. Traceability information can be used to mine the different correlations between wood properties. For example a window frame producer needs boards with long average distance between knots and wood with this

The basis of the traceability is reliable identification of wood items to associate and retrieve information on them. To identify the logs in the Nordic round wood supply chain a novel UHF transponder was developed together with robust RFID reader solutions. The novel wedge-shaped transponder is made from pulping compatible materials and it is inserted in‐ to the log end. In trials in saw mills the transponder readability was close to 100 % for intact functional tags. An ICT system solution was also developed for the data storage and transfer

The future development of the RFID based traceability should focus on further improving the reliability of the tracing close to 100 % for all logs. The main technical development

property can be assigned for production of boards for this end product.

to utilise the collected information by different actors in the value chain.

affordable there is not much demand for the tags.

322 Radio Frequency Identification from System to Applications

**6. Conclusion**

processing history.

Janne Häkli1 , Antti Sirkka2 , Kaarle Jaakkola1 , Ville Puntanen2 and Kaj Nummila1\*

\*Address all correspondence to: kaj.nummila@vtt.fi

1 Sensing and Wireless Devices, VTT Technical Research Centre of Finland, Espoo, Finland

2 Tieto Oyj, Tampere, Finland
