Modelling and simulation of an harvester head mechanism

Abstract

This paper presents an approach for modelling and simulating a harvester head mechanism in the delimbing process of hardwood stands. An original model of the mechanical transmission is developed which allows, in the early phases of design, sizing of actuators and structural elements but also the validation and optimization of the various stages of the logging operation. The considered type of trees is characterized by flexuous trunks and big branches. Hence, the current harvester heads are not enough efficient to process such trees. New designs of harvester head are required to overcome these problems. In order to predict the process performances associated to several novel architectures of harvester heads, in preliminary design stage, a modelling of the process is developed. It is based on parameterized tree models with realistic geometry. The global harvesting head model makes interact original sub-models representative of basics functions as feeding trunk into the head and cutting branches by knife. These models identified experimentally, allow a good prediction of the interactions between the different parts of the machine and trees. The modelling and simulation of harvester head mechanisms are implemented in a numerical multibody environment. Simulation results of the global model are in a good agreement with the observed behaviour of the real system and represent a design support tool to develop innovative concepts of harvester head.