Modelling of Hydraulic Forest Boom Tip Acceleration Control to Counterbalance the Gravitational Load Force in Horizontal Timber Cutting

Abstract

This paper concentrates on the forest machines, which are working in the cut-to-length method. The cutting function is an essential part of a harvester’s work in the cut-to-length method. The quality of cutting is the most significant feature of a cut. Trees should be cut without causing damage, especially end checks, to the cutting surface of wood. Nowadays end checks of logs are main problem of the cutting process. It has been observed that end checks are found in as many as 70% of the logs. The cutting damages reduce the amount of useful material and cause considerable economical loss to the sawmill and veneer industries. The study deals with the boom lowering function, which is a potential solution to avoid cutting damages during the timber cutting process. The purpose is to momentarily counterbalance the gravitational force of a log during the cross-cut. This paper presents model derivation and analysis of the kinematics, dynamics and hydraulics of the studied forest boom. The paper also shows that the model can be used as a design tool to examine the influences of hydraulics and control system to the behaviour and performance of boom tip acceleration control in a horizontal timber cutting in future studies.