Utveckling av en dynamisk Simuleringsmodell av en skotare
The predominant forestry harvesting method is based on the harvester-forwarder method, theharvester folds, branches and cuts trees, and sorts the logs into piles, while a forwarder transportsthe logs to a landing area.This master thesis work is about realization of a dynamic forwarder simulation model, and itspurpose is to provide an integrated forwarder simulation model in MATLAB/SimMechanicswhere the forwarder is based on a concept using pendulum arms to connect wheels and chassis.Active suspension control is developed and implemented into the simulation model, and finallycompared in simulation with passive suspension.In a first step, an integrated forwarder simulation model is developed, containing a simplifiedforwarder model, a tire-to-ground interaction model and a test track model. The simplifiedforwarder model is based a rigid multi-body system with a spring-damper suspension of thependulum arms. The tire-to-ground interaction model calculates the reaction forces, friction fromthe ground and applies the propulsion force. The test track model is a simplified version of thereal test track in Skogforsk. The propulsion wheel torque control is used to regulate theforwarder speed. The simulation results indicate that the model works properly to show dynamicproperties when the forwarder is driven on uneven terrain.In a second step, the original passive suspension system is replaced with a combined passive andactive suspension system proposed in this master thesis in order to reduce undesired dynamics.The comparison shows that the combined passive and active suspension system can reduce someof the undesired dynamics. However some more advanced strategy is required for betterperformance. The main aim of the thesis was to develop the simulation model including theforwarder, a general test track and the tire to ground interaction. This aim has been achieved.Additionally, a graphical user interface (GUI) is developed for making the simulation modelmore user-friendly and modular, enabling the user to easily adjust model parameters.