Cyber-physical systems (CPS) are well suited for both research and teaching. In this paper the architecture for the design of CPS controllers based on free hardware and software is presented. The advantages of this system include its flexibility, its modular structure facilitating concurrent development and its robustness, with easy evolution of existing systems. An application case study that highlights the potential of this model is detailed. Low cost modules have been chosen. As they are largely utilized they have a large community of developers and plenty related technical information can be found. They are based on free hardware and operating systems widely available. Modularity allows implementing them on existing systems, allowing easy evolution. Another significant advantage of the proposed model for both research and teaching is that, due to its low cost, it allows building more mobile robots.