The new development of cyber-physical product families currently lacks a methodically supported modularisation approach. This paper provides an approach for module-based mechatronic development, which provides design for future product variety. The state of the art in terms of mechatronic system design and modular product architecture design is presented. A modified V-model is then shown that integrates initial product architecture design and life phase modularisation. The method is applied and evaluated for the development of product family generations of robot units in a teaching course.