Scaffold-based Asynchronous Distributed Self-reconfiguration by Continuous Module Flow

Distributed self-reconfiguration in large-scale modular robots is a slow process and increasing its speed a major challenge. In this article, we propose an improved and asynchronous version of a previously proposed distributed self-reconfiguration algorithm to build a parametric scaffolding structure. This scaffold can then be coated to form the desired final object. The scaffolding is built through a continuous feeding of modules into the growing shape from an underneath reserve of modules which shows a reconfiguration time improved by a factor of $\sqrt[3]{N}$ compared to the previous and synchronous version of the algorithm, therefore attaining an $O(N^{1/3})$ reconfiguration time, with $N$ the number of modules in the system. Our algorithm uses a local motion coordination algorithm and pipelining techniques to ensure that modules can traverse the structure without collisions or creating deadlocks. Last but not least, our algorithm manages uncertainty in the motion duration of modules without negatively impacting reconfiguration time.