We developed a pruning robot that detects individual branches and prunes them after confirming their position. In this research, we considered a small type of cutting machine that was developed to lessen damage to timber, and compared the cutting capability of three types of cutting machines: industrial-use router bits, endmills, and roughing endmills. All cutting machines were similar in shape and could be downsized. However, because of differences in the design of the cutting machines, we predicted that the resistance while cutting would be different. In order to design a more compact and lighter cutting mechanism, we examined the differences in resistance by conducting experiments. As a result, the endmills were able to cut with less resistance than the router bits. Furthermore, the roughing endmills had less vibration caused by the resistance. Based on these results, the roughing endmills were found to have the smallest resistance while cutting and the most potential to cut efficiently with limited power. Then, we developed a cutting mechanism for the roughing endmills and initiated a cutting experiment in a forest to check the feasibility of the mechanism.

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We calculated the potential forest biomass that could be obtained from commercial thinning in terms of the price of domestic timber, without a subsidy for thinning. Then, we considered six subsidies, divided into three types, and examined the impact of these subsidies on forest biomass. The calculation of potential forest biomass included four conditions for judging the feasibility of commercial thinning. Under these conditions, the feasibility of commercial thinning was determined by comparing the price of domestic timber with the production cost of thinning, and calculating the amount of extractable forest biomass. For the region examined (Toei-cho, Kitashitara-gun, Aichi Prefecture, Japan), we calculated that there was a small potential amount of forest biomass in commercial thinning areas for the fiscal years 2002 to 2004. This was because the extraction ratio was low, due to the long extraction length and low price of timber in the region. When subsidies were considered, the variance in the ratio of the extractable amount of forest biomass differed when all the thinned trees were extracted and when timber alone was extracted.

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