The objective of this study is to elevate the ideal methods and issues for ergonomic research on forestry work in the future by organizing the transition of the literature, thus far while investigating the ergonomic research on forestry works in Japan. This study focuses on the literature and examines its transition from the middle of the Taisho era to the present day. The result indicates that many studies were previously conducted on “labor burden evaluation,” “safety equipment for machinery/equipment,” and “improvement of evaluation of machinery/equipment.” In recent years, however, the focus shifted to “safety education/training/skill improvement.” The findings point to a tendency to highlight worker development as a research theme. Based on these results, the study classifies the ergonomic researches into occupational accident prevention, occupational safety and health/health management of workers, construction of labor organizations/systems, and construction of educational organizations/systems. Lastly, the study presents issues that needs to be addressed in the future.

This study used a statistical model to elucidate the influence of work conditions on occupational non-fatal accidents in forestry, with the working conditions as a variable. Statistical analysis showed that operations in steep slope areas contributed to increased non-fatal accident rate, while the use of forestry machines decreased the rate of non-fatal accidents. The rate of non-fatal accident occurrence was also influenced by the age of workers, with high or low rates being observed with increased number of young or old workers, respectively. Effective measures to potentially lower the non-fatal accident rate, includes reducing the number of young workers, reducing operation in steep slope areas, increasing the number of old workers, and increasing the use of forestry machines. However, due to difficulties in modifying operations in steep slope areas or workers age, the two measures are considered non-realistic, while the use of forestry machines is practical and can be more effective in lowering non-fatal accident rate. Notably, lowering the rate of non-fatal accident among young worker is necessary to lower the overall nonfatal accident rate occurrence in forestry.

This study sought to comprehend the current state of gripping chainsaw accuracy with a focus on horizontal gripping. We also observed the effects of gripping height and ground slope. According to the guide bar angle results, 40% of the subjects had horizontal gripping accuracy, which could lead to occupational accidents such as hanging up trees or contacting adjacent trees. Beginners tended to lower the guide bar angle, whereas experienced users tended to raise it. Furthermore, there was no difference in gripping heights. Because it was surmised that there was no substantial difference in skill between the groups, we evaluated the impact of differences in the ground slope, gripping posture of the chainsaw, and throttle operation. There was no significant difference between the chainsaw gripping posture and the fingers operating the throttle. In terms of the influence of ground slope, a tendency for the guide bar to rise was significantly observed at inclinations of 0° and 10°. First and foremost, practicing to improve horizontal grasping accuracy on flat ground would be beneficial.

Forests are acknowledged as major factors in CO2 absorption, which is vital for achieving carbon neutrality. In the forestry, it is necessary to further increase productivity and the use of unmanned machinery. As a means of increasing productivity, we focused on autonomous log-loading and -unloading using forestry machinery. Instance segmentation is an image processing technique in which objects are detected in pixels following labor-intensive training; it was used to investigate autonomous log-loading and -unloading. Here, a method is proposed for obtaining the grappling position of logs by detecting individual logs using object detection. Using this method, the three-dimensional coordinates of the logs were estimated in the radial, axial, and vertical directions with maximum errors of 1.644, 1.866, and 0.407 m, respectively, and root-mean-square errors of 0.643, 0.547, and 0.150 m, respectively. The proposed method has limitations to its applications and is unsuitable for precise operations. However, it could be used effectively for searching the surrounding logs in advance of precise segmentation because the average processing time from multiple object tracking to obtaining the three-dimensional coordinates of the estimated grappling position was 0.792 s.

An automated forwarder traveling continuously on the same track produces more noticeable road surface deformations than a manually operated forwarder. Continuous travel with reduced road surface deformation can be possible by specifying the characteristics of manual travel. Additionally, automated travel can reduce labor and other costs. Therefore, we conduct continuous travel tests with the automated and manual forwarders and specify the road deformations and characteristics after each test. The results demonstrate that turning causes more soil to fill than sink for both types of travel. Additionally, the soil filled up in the curved section is particularly noticeable in automated travel. The operators in the manual forwarder do not follow the same track. Generally, the tracks departed from the previous ones by more than 0.2 m on either side. This type of travel seems to have a leveling effect on the deformed road surface; thus, it can be used for automated travel. The road for automated travel must be at least 0.2 m wide on each side in addition to the width needed for road safety. However, creating wide roads in certain locations, such as steep slopes, is challenging. Alternatively, using forwarders with small widths instead of constructing wider roads leads to lower total productivity.