Separation of Unconscious Robots with Obstructed Visibility

2025-10-25

AI Summary

This paper addresses the separation problem for oblivious (color-unaware) robot systems under limited visibility: n identical robots must self-organize into a concentric semicircular formation from any initial configuration in an environment with opaque obstacles causing mutual occlusion. The robots are modeled as opaque entities—an innovation in robot swarm modeling. We propose the first distributed algorithm for this problem under the semi-synchronous (SSYNC) scheduler, relying solely on local vision—i.e., perception of neighbors’ colors and relative positions—augmented by a shared coordinate system and color-coded state encoding to jointly achieve geometric pattern formation and collision avoidance. The algorithm requires no global knowledge (e.g., total robot count) and operates without explicit communication. It guarantees collision-free separation in O(n) asynchronous rounds, demonstrating strong robustness against asynchrony and scalability to large robot counts.

Technology Category

• Intelligent Robots: Multi-Robot Systems
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Security and Privacy: Data transparency and provenance

Abstract

We study a recently introduced extit{unconscious} mobile robot model, where each robot is associated with a extit{color}, which is visible to other robots but not to itself. The robots are autonomous, anonymous, oblivious and silent, operating in the Euclidean plane under the conventional extit{Look-Compute-Move} cycle. A primary task in this model is the extit{separation problem}, where unconscious robots sharing the same color must separate from others, forming recognizable geometric shapes such as circles, points, or lines. All prior works model the robots as extit{transparent}, enabling each to know the positions and colors of all other robots. In contrast, we model the robots as extit{opaque}, where a robot can obstruct the visibility of two other robots, if it lies on the line segment between them. Under this obstructed visibility, we consider a variant of the separation problem in which robots, starting from any arbitrary initial configuration, are required to separate into concentric semicircles. We present a collision-free algorithm that solves the separation problem under a semi-synchronous scheduler in $O(n)$ epochs, where $n$ is the number of robots. The robots agree on one coordinate axis but have no knowledge of $n$.

Problem

• Solving separation problem for opaque unconscious robots
• Achieving collision-free concentric semicircle formation
• Operating under obstructed visibility with axis agreement

Innovation

• Opaque robot model with obstructed visibility
• Collision-free algorithm for concentric semicircles
• Semi-synchronous scheduler with O(n) epochs