This theme of research has been developed around three areas: •Technologies: mechatronic systems and their actuation systems include power transmission elements from different fields, which are usually treated independently. The goal of my research is to synthesize them in a coupled manner. •Models: the models to set up in order to design a system are of different natures. Simulation models are used to calculate all quantities that influence the choice of the components. Evaluation models enable lifetime or reliability to be calculated. Estimation models give rapid access to component characteristics, generally obtained after detailed design. •Methods: to optimize a design, it is advantageous to develop meta-models to replace time consuming simulations, to analyse the uncertainty of results, and to help the implementation of the design procedures.