This book is focused on the model based design methodology for mechatronic systems in the conceptual stage. It proposes a generic framework model for effective and semi-automated design candidate generation in the conceptual design stage. The specific application is focused on the mobile robots. An application specific toolkit was developed as a tool based on the developed methodology. The methodology specifies toolkits and model libraries which are realized on the example of mobile robotic platform design. Additional toolkits can be developed according to this methodology. The practical implementation of the Mobile Platform Toolkit is presented based on real examples. Two similar mobile robots in a different design stage were selected to illustrate the use of the toolkit. The Workpartner robot from Aalto University is used as an analytical example and the UGV platform from Tallinn University of Technology is utilized as a synthesis example where the developed approach was applied in the conceptual design stage.