Efficient analyses for the mechatronic design of mechanisms with flexible joints undergoing large deformations

The models used in the conceptual phase of the mechatronic design should on the one hand capture the dominant system behaviour while on the other hand complicated models should be avoided as these are too laborious to build and the analysis is too time-consuming. One or two dimensional lumped parameter models can be used for their simplicity. However, even for rather simple mechanical systems such models may ignore relevant three-dimensional or geometric non-linearities. Models obtained with standard linear finite element models often need many elements to achieve sufficient accuracy. In this paper analyses with a multibody approach based on non-linear finite elements are discussed. Due to the sound inclusion of the non-linear effects at the element level only a rather small number of elastic beam elements are needed to model typical components accurately. Configuration dependent linearised models can be generated for control system design. This approach is offered by the SPACAR software package and its applicability is demonstrated with the analysis of a mechatronic device. The effects of e.g. non-linearities, non-co-located control in three dimensions and relevant natural frequencies are analysed easily and quickly with the low-dimensional and accurate models offered by the modelling approach.