@article {57, title = {Morphable structures from unicellular organisms with active, shape-shifting envelopes: Variations on a theme by Gauss}, journal = {International Journal of Non{\textendash}Linear Mechanics}, volume = {118}, year = {2020}, pages = {103278}, abstract = {

We discuss some recent results on biological and bio-inspired morphing, and use them to identify promising research directions for the future. In particular, we consider issues related to morphing at microscopic scales inspired by unicellular organisms. We focus on broad conceptual principles and, in particular, on morphing approaches based on the use of Gauss{\textquoteright} theorema egregium (Gaussian morphing). We highlight some connections with biological cell envelopes containing filaments and motors, and discuss ideas for the implementation of Gaussian morphing in surfaces actuated by active shearing or stretching.\ 

}, keywords = {Active shells, cell motility, Deployable structures, Fluid{\textendash}structure interaction, Gaussian morphing, Micro-swimmers, soft robotics, Unicellular swimmers}, doi = {10.1016/j.ijnonlinmec.2019.103278}, author = {Giancarlo Cicconofri and Giovanni Noselli and Marino Arroyo and Antonio De Simone} } @article {48, title = {A study of snake-like locomotion through the analysis of a flexible robot model}, journal = {Proceedings of the Royal Society A}, volume = {471}, year = {2015}, pages = {20150054}, abstract = {

We examine the problem of snake-like locomotion by studying a system consisting of a planar inextensible elastic rod with adjustable spontaneous curvature, which provides an internal actuation mechanism that mimics muscular action in a snake. Using a Cosserat model, we derive the equations of motion in two special cases: one in which the rod can only move along a prescribed curve, and one in which the rod is constrained to slide longitudinally without slipping laterally, but the path is not fixed a priori (free-path case). The second setting is inspired by undulatory locomotion of snakes on flat surfaces. The presence of constraints leads in both cases to non-standard boundary conditions that allow us to close and solve the equations of motion. The kinematics and dynamics of the system can be recovered from a one-dimensional equation, without any restrictive assumption on the followed trajectory or the actuation. We derive explicit formulae highlighting the role of spontaneous curvature in providing the driving force (and the steering, in the free-path case) needed for locomotion. We also provide analytical solutions for a special class of serpentine motions, which enable us to discuss the connection between observed trajectories, internal actuation and forces exchanged with the environment.

}, keywords = {bioinspired robots, Cosserat rod models, limbless locomotion, snake locomotion, soft robotics, undulatory locomotion}, doi = {10.1098/rspa.2015.0054}, author = {Giancarlo Cicconofri and Antonio DeSimone} }