This video is an Applied Research Methodology final presentation by Shaojie Ma, a PhD student at Universitat Politècnica de València. The presentation introduces the TwinMobAge research project, which explores how digital twin technology can support age-adaptive, modular, and sustainable mobility-assistance products for older adults. It focuses on the design and evaluation of a modular rollator, considering usability, safety, physiological decline, intuitive cognition, prior knowledge, technological familiarity, and cultural context. The video also explains the research questions, methodology, experimental plan, project management structure, funding logic, and future publication direction.