The Observation of the Morphological Computation Phenomenon in Nature is the First Step for the Formalization of the Principle

A theory, by definition, is a generalization of some phenomenon observations, and a principle is a law or a rule that should be followed as a guideline. Their formalization is a creative process, which faces specific and attested steps. The following sections reproduce this logical flow by expressing the principle of Morphological Computation as a timeline: firstly the observations of this phenomenon in Nature has been reported in relation with some recent theories, afterward it has been linked with the current applications in artificial systems and finally the further applications, challenges and objectives will project this principle into future scenarios. The Morphological Computation Principles as a New Paradigm for Robotic Design The Observation of the Morphological Computation Phenomenon in Nature is the First Step for the Formalization of the Principle When we see a dolphin swim, we are marveled by how such a rapid, elegant and strong movement can seem so simple. The dolphin motion has been subject of study since the time of Aristotle. In recent years, it has been found that the high velocities reached by these animals are possible thanks to the formidable mechanical properties of their body. The motion in water is extremely difficult due to the density and viscosity of the medium that imply an exceptional longitudinal force that slows the movement down. The combination of the skin structure, of the appendage shapes, and of the behavioral mechanism during motion allows reducing the drag force, enabling the effective and graceful movement that we all can admire [8]. In Nature, the shape, the geometry, the placement and the compliance properties of the body parts define the perception and the interaction with the environment, thus connecting such kind of features with the expressed behavior, synergistically. All these features can be gathered together in the term morphology. We could say that any transformation of information can be named as computing, and thus, in that sense, Morphological Computation endows all those behaviors where computing is mediated by the mechanical properties of the physical body [23, 22, 21]. There are at least three different cases we can use as reference to describe this transformation: • Shape: the case in which the shapes, as body structure, specifies the behavioral response of the agent. • Arrangement: the case in which the geometrical arrangement of the motors, perceptive and processing units implies specific computational characteristics. • Mechanical properties: the case in which the mechanical properties allow emergent behaviors and highly adaptive interaction with the environment, impossible elsewhere. The first point of view opens the way to all that kind of mechanical structures that facilitate the behavioral expression of a particular agent. A special structure allows many animals to move in the environment with elegant and coordinated gestures: the skeleton. All vertebrates share a similar organization evolved with the precise function to assist movements and in addition to protect internal organs. The term Simplexity has recently been used to explain the solutions that Nature found to simplify the control of complex phenomena [1]. For example, the S-shape characteristic of the animal backbone, and in particular the curvature of the neck, allows the disjunction of the rotations of the head respect to the rest of the body (Figure 1 left). This in turn allows the alignment of the head with the ground in order to stabilize the vision system and thus giving a reference for the control of movements. The complexity added in the morphology of the spine helps to simplify the control. A related example of morphology, but in sensing, is