Reconfiguration Algorithms for Cubic Modular Robots with Realistic Movement Constraints

TL;DR

This paper presents new reconfiguration algorithms for cubic modular robots that incorporate realistic movement constraints, such as interlocking features and passive modules, demonstrating universality in structure assembly.

Contribution

It introduces a model capturing practical movement constraints and proves universality results for reconfiguring structures with and without auxiliary modules.

Findings

Any connected polycube can be assembled with auxiliary modules.

Structures with a certain feature size can be assembled without extra modules.

The model better reflects real-world modular robot constraints.

Abstract

We introduce and analyze a model for self-reconfigurable robots made up of unit-cube modules. Compared to past models, our model aims to newly capture two important practical aspects of real-world robots. First, modules often do not occupy an exact unit cube, but rather have features like bumps extending outside the allotted space so that modules can interlock. Thus, for example, our model forbids modules from squeezing in between two other modules that are one unit distance apart. Second, our model captures the practical scenario of many passive modules assembled by a single robot, instead of requiring all modules to be able to move on their own. We prove two universality results. First, with a supply of auxiliary modules, we show that any connected polycube structure can be constructed by a carefully aligned plane sweep. Second, without additional modules, we show how to construct any structure for which a natural notion of external feature size is at least a constant; this property largely consolidates forbidden-pattern properties used in previous works on reconfigurable modular robots.