Search

There is a need to decrease the costs of cut-to-length operations. The harwarder, a one-machine system with the potential to reduce the costs, has been compared to the two-machine system (TMS) at the stand and regional levels but not at the national level, which is important as basis for decision to implement. The objective was therefore to analyze its potential on a large scale in Swedish final fellings. It was evaluated using two modeling approaches in conjunction with data representing around 30% of Sweden's yearly final fellings from five forestry organizations. The analyses revealed that total costs could be reduced by around 3% if up to 50% of the total volume was logged using harwarders rather than the TMS. This would require the introduction of up to 250 harwarders into machine fleets that currently use only the TMS. The two modeling approaches gave similar results. It was concluded that the harwarder may need to demonstrate greater potential to justify a full-scale implementation in Swedish forestry, but the machine could be improved through technological development, especially through automation. [ABSTRACT FROM AUTHOR]

The mechanization of roundwood harvesting in Sweden has historically cut costs rapidly. However, machinery and work methods have conceptually stayed the same since the introduction of the single-grip harvester. Current trends indicate that the next major wave of development will be based on automation, and that teleoperation is a step in this direction. This study aims to evaluate the economic potential of semi-automated tele-extraction compared to standard forwarding within the Nordic CTL two-machine harvesting system. The initial scenario examined autonomous terrain transportation with teleoperation during loading and unloading. A Discrete Event Simulation was implemented in the AnyLogic software. Input data included 1100 Swedish harvest sites, with in total 1.6 million m3 and extraction distances from 20 to 1500 m. Scenarios with different numbers of teleoperators for a fleet of ten forwarders were tested. The optimum number of operators was seven per ten forwarders, resulting in a potential extraction cost reduction of 7% compared to standard forwarding. Extraction distances further than 500 m enabled use of five or six teleoperators, resulting in potential cost reductions of up to 15%. The highest potential cost reductions were linked to increased time used for autonomous driving, increasing the teleoperator availability for other machines. The simulation model provides a framework for further evaluation of new scenarios of automation and teleoperation of forwarders. [ABSTRACT FROM AUTHOR]

Autonomous navigation in forest terrain, where operation paths are rarely straight or flat and obstacles are common, is challenging. This paper evaluates a system designed to autonomously follow previously demonstrated paths in a forest environment without loading/unloading timber, a pre-step in the development of fully autonomous forwarders. The system consisted of a forwarder equipped with a high-precision global positioning system to measure the vehicle's heading and position. A gyro was used to compensate for the influence of the vehicle's roll and pitch. On an ordinary clear-cut forest area with numerous stumps, the vehicle was able to follow two different tracks, three times each at a speed of 1 m s-1, with a mean path tracking error of 6 and 7 cm, respectively. The error never exceeded 35 cm, and in 90% of the observations it was less than 14 and 15 cm, respectively. This accuracy is well within the necessary tolerance for forestry operations. In fact, a human operator would probably have a hard time following the track more accurately. Hence, the developed systems function satisfactorily when using previously demonstrated paths. However, further research on planning new paths in unknown unstructured terrain and on loading/unloading is required before timber transports can be fully automated. [ABSTRACT FROM AUTHOR]