Morpho-functional machines: Basics and research issues

We define morpho-functional machines as machines which are adaptive not only by means of their neural substrate, but by being able to change their morphology as they perform a task in the real world. Changes in agents can occur at several time scales: short-term, ontogenetic, and phylogenetic. All of these need to be taken into account in designing morpho-functional machines. Studying natural systems, building robots with many degrees of freedom, and artificial evolution (in particular artificial ontogeny) are methods to gain insights into the field. Because the field is only in its infancy, there are no generally accepted methodologies and a multiplicity of methods must be employed to make progress. The paper concludes by identifying a number of important research questions.