Masahiro Iwaoka

Feasibility of a Harvesting System for Logging Residues as Unutilized Forest Biomass

The concept of a “harvesting system for unutilized forest biomass by a processor and a forwarder” is examined for the purpose of constructing a system to harvest logging residues (or slashes) as a new resource for energy. The rate of slash harvesting, α, and the energy input rate of hauling slashes,p (%), are defined as indices of the possibility of harvesting slashes and the utilization of slashes for energy, respectively. From an analysis of the field experiment, both the volume of logs hauled by the forwarder per day,EF (m3/day), andp are expressed as functions of the hauling distance,L(m). The productivity of the processor,EP (m3/day), andL were used to calculate α. Results showed that α was approximately 0.95 for the experiment site, indicating that almost all the slashes could be hauled. It was recognized that the energy utilization of slashes was feasible for this site becausep was less than 1 %. The hauling cost per unit weight of slashes was calculated as 15.4 yen/kg on an oven-dry weight basis. This high cost clarified that the cost must be reduced by taking measures such as enhancing the hauling efficiency of the forwarder.

Performance of small harvester head in a thinning operation

Medium to large size harvester heads mounted on large machines are popular in Japan. These machines encounter some problems during thinning operations,e.g. damage to residual stand and the compaction of soil. The performance of these large harvesters was compared with that of smaller ones operating simultaneously in the same line thinning operation of the same stand. The results of a time study showed that mean cycle times for the smaller and larger harvesters were not significantly different. This means that the work efficiency of the smaller harvester can be at the same level as the larger harvester on sites similar to those of this study. The mean values “Feed” element of the cycle time, however, were significantly different. Although this time difference appears to provide an advantage to the larger harvester, simulation results show that the advantage is not great enough to significantly shorten the total cycle times. That is to say, the work efficiency remains essentially the same even if the feeding performance of the small size harvester becomes as high as that of larger ones. The small harvester performs adequately in thinning operations, and is not inferior to the larger ones. This result indicates that there is economic potential for small base machines that can be mounted with small harvester heads, resulting in less damage to residual trees and site soils during thinning operation.

Chapter 6 – Machinery and Information Technology for Biomass Production

This chapter outlines machinery, information technology, infrastructure, and their integration for efficient biomass production in agriculture and forestry. Both agriculture and forestry in Japan are performed in regions of large-scale production that is unique compared with other Asian countries. The original technologies that have been developed and implemented for this unique situation as discussed in this chapter may be adopted as advanced technologies for other situations. The first part of the chapter summarizes the biomass production technology used in agriculture. Introducing seeding machines leads to an agricultural system with low production and labor costs, and implementing the information system is also of importance to establish more efficient production systems. The second part covers the forestry on forest planning, management, and harvesting technologies, including discussions on historical background. The extensive application of geographic information system (GIS)-based precise management technology as an information system to aid forestry production is also reviewed in this chapter.

Motion analysis of a semi-legged vehicle with soil deformation taken into account

A semi-legged vehicle was designed for forestry use. The equation of motion for the machine coupled with the equation of motion for soil was derived. Furthermore, the motion of the machine was analyzed taking into account soil deformation. The Extended Distinct Element Method, which can analyze both continuous and non-continuous materials, was used as a soil model. The effects of foot area and spike length were simulated by using two kinds of uniform soil. The specific power of a foot area of 3,200 cm2 was smaller by 0.025 than that of a foot area of 1,600 cm2 on soft soil. This was equal to the consumption energy for moving 2.5% of the machine weight, about 140 kgf. The maximum values of the forces acting on the second hydraulic cylinder were 300 kN and 500 kN, and the weights of the hydraulic cylinder generating these forces were 121 kgf and 229 kgf with spikes that were 0 cm and 30 cm long on hard soil, respectively. In a walking motion, such as lowering the boom to the ground, raising the stabilizers, and advancing the machine, the machine with a larger foot area and shorter spikes was more suitable for lightening the total weight and improving energy efficiency.

Improvement and evaluation of the feller-buncher head

The high quality forest machines have recently become very popular in Japan. Many improvements on these machines have been made to fit the Japanese forests. This report describes the improvement and evaluation of the feller-buncher head of the prototype machine: FG-35. This head is mounted on the telescopic and knuckle-boom carrier. The prototype machine was improved to cut the trees, felled down on the ground or felled side ways by the storm as in the Kyushu district. And also the machine was improved so that it could be driven well without crashing the chainsaw-bar by the beginners. The testing operation of this machine carried out in Sumita-chou in Iwate and in Kuzu-chou in Oita. The productivity of the machine can be estimated at about 20 m3/h. The results of the improvement on the machine can be said to be good.