Modelling and simulation utilized in research and development of mobile hydraulics

This thesis deals with modelling and simulation applied to mobile hydraulics. The main features of mobile hydraulics are described and the benefits of a simulation approach in research and development of mobile machinery are discussed. Numerically efficient and easy-to-parameterize models for mobile hydraulics components are created. This makes it possible to achieve a computationally efficient simulation model of an entire machine and the number of parameters is as low as possible. The models include all the essential functions of the components in order to carry out system level design of such machine systems. The pump system model consists of a variable displacement pump including LS-regulator and power restrictor. The loss model is based on the Dorey model and the identification is made semi-empirically with a reduced number of parameters. The mobile valve model includes semi-empirical sub-models of the main valve spool, pressure compensator/flow sharing compensator, load drop check valve, anti-cavitation valves and shock valves. An empirical model for an oil cooler and polynomial fit for passive heat transmission of the machine are also suggested. A method for defining mobile valve dynamics without performing measurements is introduced and verified against the mobile valve used in the example machine system. The simulation software implementation and the advantages of the approach are presented. As a result, an engineering tool for R&D operations is created. An actual company-based R&D case demonstrates the application. Simulation study of a forest machine dealing with machine energy efficiency is carried out.