Harvest tracking and navigation with GPS
Substantial growth in civilian applications of the Global Positioning System (GPS) is evident across North America and around the world. Forestry applications have not lagged. GPS is involved in diverse applications in forestry, ranging from logging truck fleet management to harvest block layout. This thesis reports on a study that investigated the viability of using GPS to navigate forest harvesting equipment. The focus of the research investigation was to determine the viability of on-board, real-time GPS technology, teamed with GIS, in partial harvesting navigation. The viability of the system was determined on the basis of its ability to satisfy the same post-harvest quality assessment criteria and harvest productivity rates as exist in present practice. Motivated by the savings that would results if costly harvest block layout procedures could be eliminated, the study examined GPS navigation performance using Valmet and Timberjack single-grip harvesters in partial harvesting experiments in Sussex, New Brunswick and Hinton, Alberta, respectively. The New Brunswick experiment involved a late autumn harvest in a mixed-wood condition, while the Alberta experiment was carried out in a pure softwood condition under sever winter conditions. The treatment involved GPS-assisted navigation of the desired harvesting pattern displayed over covertype map detail on a pen-based PC computer connected to a real-time differential GPS receiver. The control for the test used a portion of the harvest block in which no navigation assistance was utilized. Harvest performance criteria recorded during treatment and control harvesting were productivity (trees/hour) and post-harvest quality (coverage). Since physical objects interfere with GPS reception, it was expected that tree cover, would be the single most influential factor determining harvest productivity and post harvest quality for GPS assisted harvest navigation. For this reason, each experiment site was characterized by stand density (tree/ha) and tree cover type (% softwood and hardwood) in a pre-harvest survey with uniformly distributed sample points. In both control and GPS-navigated harvesting, reception quality was indicated (recorded) by the number of blocked satellites. The analysis examined the harvest block conditions and satellite reception. The findings showed that the introduction of the GPS in harvest navigation did not adversely effect the quality of the harvest but it may decrease the production rate of the harvest, especially at higher harvest rates, as was witnessed in the Alberta test site. The study also showed that there is a relationship between the stand density under which the harvest machinery is operating and the GPS reception quality, as indicated by the number of blocked satellites. Key words: GPS, GIS, forestry, navigation, harvest methods, mobile mapping.