Erik Arvidsson, Anders Rowell, Linnea Hansson, Håkan Lideskog, Mikael Rönnqvist. (2026). Comparison of manual and automated coverage path planning for mechanized forest regeneration. Silva Fennica vol. 60 no. 1 article id 25018. https://doi.org/10.14214/sf.25018

Keywords: site preparation; planting; mechanization; automation; precision forestry; routing

Highlights: Automated coverage path planners TerraTrail and Pathfinder outperform manual operators driving the PlantMax planting machine in coverage across all test sites; Pathfinder demonstrated the shortest path lengths, especially in constrained environments, with up to 14% shorter paths compared to manual planning; The study emphasizes the potential of autonomous path planning systems to reduce labor dependency, enhance sustainability, and improve the efficiency of forest regeneration operations; The automated planners effectively accounted for vehicle constraints such as terrain and soil moisture conditions, optimizing routes for more efficient regeneration.

Abstract | Full text in HTML | Full text in PDF | Author Info

In Finland and Scandinavia, even-aged forest management predominates, often including mechanical site preparation and manual planting. Growing labor shortages and increased demand for sustainability have driven interest in mechanized and autonomous planting systems. This study evaluates two automated Coverage Path Planners (CPP), Pathfinder and TerraTrail, developed to optimize planting routes for mechanized forest regeneration. Their performance is compared to the routes of the manually operated mechanized planting machine, PlantMax. Three operational sites in Sweden, representing varied terrain and hydrological conditions are evaluated. The evaluation focuses on coverage, Euclidean and Dubins path lengths. Both CPPs incorporate Digital Elevation Models (DEM), Depth-to-Water (DTW) maps and vehicle-specific kinematics to generate planting routes. Two scenarios are evaluated: one where the CPPs neglect the DTW map, and another where the CPPs are constrained to avoid DTW values below 0.3 m. Results show that automated CPPs achieve 15–19% higher coverage than manual planning on average. Pathfinder showed similar normalized path lengths in an unconstrained scenario as the manual operator, but 14% shorter in the constrained environment. TerraTrail shows 7% longer normalized path lengths in an unconstrained scenario, while the constrained scenario shows similar path lengths as the manual operator. These findings emphasize the potential of deploying automated CPP systems to enhance precision, sustainability, and labor efficiency of silvicultural operations. The CPPs support both autonomous deployment and decision support tool for operators. Further refinement, including combining both CPPs to leverage the best functions of each, along with reversible path planning, could enhance their value in forestry practices.

Arvidsson, Luleå University of Technology (LTU), SE-971 87 Luleå, Sweden https://orcid.org/0000-0001-7679-0203 E-mail: erik.arvidsson@ltu.se
Rowell, Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0009-0000-2810-1434 E-mail: anders.rowell@skogforsk.se
Hansson, Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0000-0002-9788-1734 E-mail: linnea.hansson@skogforsk.se
Lideskog, Luleå University of Technology (LTU), SE-971 87 Luleå, Sweden https://orcid.org/0000-0002-9862-828X E-mail: hakan.lideskog@ltu.se
Rönnqvist, Université Laval, 1065, avenue de la Médecine, Local 1504, Québec G1V 0A6, Canada https://orcid.org/0000-0002-1940-6129 E-mail: mikael.ronnqvist@gmc.ulaval.ca

article id 23062, category Research article

Tobias Semberg, Anders Nilsson, Rolf Björheden, Linnea Hansson. (2024). Real-time target point identification and automated log grasping by a forwarder, using a single stereo camera for both object detection and boom-tip control. Silva Fennica vol. 58 no. 1 article id 23062. https://doi.org/10.14214/sf.23062

Keywords: vector analysis; forwarder; forest operations; loading; boom automation; object detection; stereo camera

Highlights: Simple target-point detection in real time using only a stereo camera; Sturdiness ensured through the simple feedback system based on the same camera; Automated boom-tip control and log grasping successfully tested on full-sized forwarder; A step toward semi-automation (operator support) or autonomous forwarding.

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The forest industry is constantly striving to increase productivity and cut costs, and many research and innovation projects are currently focusing on semi-automated or autonomous systems. A key element, with several possible solutions, is automated log grasping, where researchers and manufacturers are looking for efficient and sturdy ways to solve the task in real-time forwarding operations. This study presents a simple method for automated log grasping using only a single stereo camera for object detection (log and grapple) and a simple controller moving the boom, with feedback from the camera as boom-tip control. The accuracy, precision, and repeatability of the method was tested on a full-scale forwarder. Boom movements were examined from two different start positions in relation to the target position, with the log placed at three different angles. The overall log-grasping success was also evaluated. The tests were performed in a full-scale, real-time operation, without hand-eye calibration or other sensor data from the machine. The method was precise, with high repeatability, but the grasping point showed a minor systematic offset, depending on log angle. However, the deviation in accuracy was too small to affect the success rate. In practice, the most difficult log angles can be avoided by moving the machine slightly. The log grasping method may become part of an autonomous forwarding system or could provide operator support in semi-automated systems.

Semberg, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: tobias.semberg@skogforsk.se
Nilsson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: anders.nilsson@skogforsk.se
Björheden, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4158-102X E-mail: rolf.bjorheden@skogforsk.se
Hansson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-9788-1734 E-mail: linnea.hansson@skogforsk.se

Category : Discussion article

article id 23053, category Discussion article

Back Tomas Ersson, Linnea Hansson, Jussi Manner, Per Sandström, Johan Sonesson. (2023). Forest management in northern Fennoscandia: the need for solutions that mitigate conflicts during forest regeneration and increase the use of continuous cover forestry. Silva Fennica vol. 57 no. 3 article id 23053. https://doi.org/10.14214/sf.23053

Keywords: mechanical site preparation; reforestation; reindeer husbandry; indigenous rights; natural resources conflict; Sámi; Sápmi

Highlights: In Sápmi, increased use of continuous cover forestry (CCF) can reduce the frequent conflicts between forest industry and reindeer herding communities; Nordic forestry needs to develop new technical solutions for gentle and lichen-adapted mechanical site preparation during CCF in Sápmi; Such site preparation technology will promote pioneer tree species’ germination and growth, and increase the forest industry’s acceptance of CCF.

Abstract | Full text in HTML | Full text in PDF | Author Info

Today, conflicts often occur in northern Fennoscandia (also known as Sápmi) between forestry and reindeer husbandry. Continuous cover forestry (CCF) is requested by both reindeer herding communities and the general public and is becoming more common, but the forest industry criticizes CCF for lower wood production. Mechanical site preparation (MSP) increases regeneration success and, thus, increases wood production in CCF. To reduce the conflict between forestry and reindeer husbandry, MSP in Sápmi should destroy as little ground lichen as possible. Today, there are no solutions for gentle and lichen-adapted MSP in CCF. Thus, there is a strong need to develop and test new technical solutions that increase regeneration success in a lichen-adapted way during CCF in Sápmi. We suggest that MSP solutions be developed which are gentle, work selectively and function in shelterwoods, gap cuts, and selection cutting stands. We envision that these solutions could fill the gap between the desired adaptivity on the part of the reindeer herding communities and the desired efficiency on the part of the forest industry. Such MSP technology would contribute to increased acceptance of CCF in the forest industry, higher biodiversity, and considerably reduce the conflict between forestry and reindeer herding communities.

Ersson, Swedish University of Agricultural Sciences (SLU), School of Forest Management, SE-739 21 Skinnskatteberg, Sweden https://orcid.org/0000-0003-2442-7482 E-mail: back.tomas.ersson@slu.se
Hansson, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0000-0002-9788-1734 E-mail: linnea.hansson@skogforsk.se
Manner, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
Sandström, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, SE-901 83 Umeå, Sweden https://orcid.org/0000-0003-0977-0071 E-mail: per.sandstrom@slu.se
Sonesson, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0000-0002-2018-7496 E-mail: johan.sonesson@skogforsk.se

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