UCD Method using VR and related techniques for designing complex system

User Centered Design (UCD) considers the users and their needs throughout the process of design of a software application. In the case of the design of a mixed product (including software, and mechanical and electronic equipments), difficulty resides in the production of an object that can be evaluated at each iteration of the design cycle. The use of Virtual Reality and related techniques as Augmented Virtuality and Augmented Reality bring an affordable solution to allow iterative evaluation as defined in UCD. We propose an adaptation of UCD which simplifies the transition from the concept to the end product. We apply this approach to innovating assistive robotics.