A Cut-To-Length (CTL) forest harvester is used for felling, delimbing and bucking of the tree stems as forwarder is used to forward the logs cut to length to roadside landing for highway transport to the refining facilities like saw-and pulp & paper mills. Fuel consumption of forest harvesting operation is becoming a more and more important cost factor as the fuel prices are raising constantly. A number of studies exist on various hybrid systems related to on-& off-highway vehicles and work machines. This paper deals with technological possibilities and potential to cut down fuel consumption of a CTL harvester by implementation of a hydraulic hybrid system that is mainly designed to take care of the highest power demands. In order to be successful in this aim, a detailed analysis of the work cycle and present power management and transmission systems are needed. Engine load data together with relevant Arcnet and CAN bus messages as well as needed hydraulic system parameters are logged during actual work in order to understand the actual nature of the application in terms of work cycle. This study is focusing on a hydraulic hybrid system, as it seems to be an applicable solution to mobile work machinery in question. Howevera background review of other hybrid solutions is also given. Some of the relevant advantages of a hydraulic hybrid system in forest machine application are also explained in this paper. Based on the prestudy and analysis on the work cyclea promising potential for hydraulic hybrid system can be seen in a CTL harvester. Future work to be done is proposed to include simulations to make a more detailed dimensioning of the components and design of the system possible already before building an actual test setup.

Forest resource data is important in targeting the forestry operations, and it is in the hearth of the precision forestry concept. The forest resource data can be produced with many techniques, and the number of existing forest data sources has increased during the years. In addition to the forest resource data, other data describing the circumstances of the forest site, such as trafficability and weather conditions, are available. In Finland, a forest data platform gathers the data sources under a single service for easier implementation of the precision forestry applications. This data is useful in operations planning, but it also describes the conditions that prevail when the forest machine arrives to the forest site. This study proposes data fusion between fieldbus time series of the forest machine and the forest data. The fused dataset enables explorative statistical analysis for examining the relationship between the machine performance and the forest attributes and provides data for building predictive models between the two. The presented methods are applied into a dataset generated from a field test data. The results show that some fieldbus time series features are predictable from forest attributes with R 2 value over 0.80, and clustering methods help in interpreting the machine behavior in different environments. In addition, an idea for generating a new forest data source to the forest data platform based on the fusion is discussed.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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