Astounding examples of massively parallel processing, multi-cellular organisms are an extremely interesting source of inspiration for the design of electronic computing machines, particularly when considering how extremely complex global behaviors (the most remarkable example being, of course, intelligence) are obtained through the cooperation of numerous very simple elements (the cells). The implementation of bio-inspired systems in silicon, however, is quite difficult, due to the sheer number and complexity of the biological mechanisms involved. Conventional approaches exploit a very limited set of biologically-plausible mechanisms to solve a given problem, but often cannot be generalized because of the lack of a methodology in the design of bio-inspired computing machines. This lack is a consequence of the heterogeneity of the hardware solutions adopted, which is itself due to the lack of architectures capable of implementing a wide range of bio-inspired mechanisms.
The goal of the CellDesign project, which is in fact at the origin of the CARG since it is the basis of the professorship award granted to Prof. Tempesti, is the definition of a universal architecture and of a design methodology for the conception of bio-inspired digital hardware.
Biological inspiration in the design of computing machines finds its source in essentially three biological models: phylogenesis (P), the history of the evolution of the species, ontogenesis (O), the development of an individual as directed by his genetic code, and epigenesis (E), the development of an individual through learning processes (nervous system, immune system) influenced both by their genetic code (the innate) and by the environment (the acquired). The architecture to be developed in the proposed project will be capable to support specialization and adaptation through the modification of the resources depending on the application and on the model of bio-inspiration to be implemented.
In fact, Nature is change: adaptation and specialization are key features of all biological organisms. As a consequence, no bio-inspired architecture can be rigid, but must rather be able to adapt and specialize depending on the desired application. This requirement, a major obstacle until recently, can today be satisfied by exploiting a technology known as reconfigurable logic. This technology is based on VLSI circuits that can be programmed to implement different hardware architectures. The circuits can then be reset and re-programmed at will, a feature that makes them a vital resource in the implementation of bio-inspired systems.
Integrating reprogrammability into an architecture, however, is far from trivial. The heterogeneity of the applications that can potentially be implemented poses considerable design problems: a novel kind of architecture needs to be developed to fully exploit the potential of reconfigurable logic for bio-inspired systems. The conception of such an architecture is the first step of the proposed project.
Defining an architecture for bio-inspired machines is not sufficient to achieve the goals of the project, which aims at providing an integrated environment for the design of such machines. Such an environment should include a customizable design flow allowing the user to concentrate on the desired approaches. The three models of bio-inspiration are well-suited to different aspects of an architecture, and the user should be able to exploit the models separately, as well as together.
The key feature of the proposed environment is then the automatization of a large part of the design flow. The intervention of the user will be required only to decide which bio-inspired models are required by the application and the environment will then automatically handle the implementation of the models into a reprogrammable platform.
The development of a proper design methodology for bio-inspired systems is the logical next phase for a domain that is finally reaching maturity. Systems inspired by biological mechanisms are carving themselves a niche in several areas of computation, but the solutions adopted often cannot be generalized for the lack of a universal architecture capable of integrating the different approaches. In order to simplify the implementation of a wide range of quasi-biological mechanisms, the CellDesign project aims at defining a complete design environment for this kind of systems.
Prof. Gianluca TEMPESTI