Going beyond naturally occurring materials, Metamaterials exploit a design at the microscale resulting in macroscopic behaviour, to achieve different or even new properties that can have a wide range of applications. By incorporating sensors, actuators and control, Robotic Metamaterials can achieve even more extremely different behaviour such as odd elasticity. By using local control and non-reciprocal couplings between actuators, an asymmetric elastic response can be achieved. Due to the non-conservative nature of this coupling, the system has a tendency to cycle and give rise to complex behaviours such as locomotion. Through simple and localized control, complex material behaviour is achieved, where the body is performing the computation and no complex control or computations systems are required. In this work, a new unit cell for a metamaterial that achieves this odd elasticity is designed, manufactured, and finally tested. The unit cell consists of 3 hexagonal mechanisms with compliant joints and a linear actuator inside and is locally controlled. By using a novel Actuator design and engineering principles such as compliant mechanisms, a unit cell design is achieved that has 10 times smaller scale per area and 15 times higher strength-to-weight ratio compared to existing work. Finally, this unit cell was characterized and combined into a larger lattice showcasing the possibilities for future research into the behaviour of odd elastic metamaterials.

Vibrations and disturbances are becoming more of a concern as lightweight, flexible structures in high-tech systems are pushed towards faster speeds and higher precision. Active Vibration Control (AVC) methods have been effectively used to attenuate vibrations and increase the bandwidth of these systems. With the miniaturisation of electronics, an increasing amount of sensor and actuator pairs can be used for AVC applications. Not only does this allow for higher active damping, it also grants more flexibility in terms of control. This trend has led to the study of robotic metamaterials and meta-structures: large-scale engineered materials build out of a repeating pattern of unit cells, where each unit cell contains a sensor, actuator and sometimes even a computing unit. The optimal control architecture to use for these systems is a difficult dilemma, since decentralised and centralised control schemes both have fundamental trade-offs in terms of performance and scalability. In this paper we study distributed control, a promising middle-ground solution that is hardly used in AVC applications. We show with the use of LQR that a distributed control architecture can achieve optimal performance in the low-frequency range for robotic materials with relative measurements. Additionally, the actuators use lower maximum control forces and a distributed control architecture remains scalable for implementation in large-scale systems. In this paper the robotic cantilever beam is studied as a specific example as it represent many typical high-tech applications. Furthermore, implications on periodic robotic meta-structures are made using LQR in the Spatial Fourier Domain.