Unidirectional transport in robotic mechanical metamaterials

Over the last few years, there has been an explosion of activity on non-reciprocal metamaterials, namely, which transmit motion in one direction, but block it in the other. However, to date, non-reciprocal transmission has only been achieved for a limited range of frequencies and input magnitudes
Here, we introduce a novel robotic mechanical metamaterial that overcomes these limits.
Each building block is a minimal robot that is able to sense the behavior of its neighbor and act consequently, which opens the way to new types of interactions. We leverage this platform to program asymmetric non-equilibrium interactions and show that the system as a whole supports first-of-their-kind unidirectionally amplified waves.
As a result, the system achieves unprecedented broadband and attenuation-free unidirectional transport of mechanical energy.