Optimal Motion Planning for Two Square Robots in a Rectilinear Environment

Fuente: arXiv
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Auteurs principaux: Agarwal, Pankaj K., de Berg, Mark, Holmgren, Benjamin, Steiger, Alex, Struijs, Martijn
Format: Preprint
Publié: 2026
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author Agarwal, Pankaj K.
de Berg, Mark
Holmgren, Benjamin
Steiger, Alex
Struijs, Martijn
author_facet Agarwal, Pankaj K.
de Berg, Mark
Holmgren, Benjamin
Steiger, Alex
Struijs, Martijn
contents Let $\mathcal{W} \subset \mathbb{R}^2$ be a rectilinear polygonal environment (that is, a rectilinear polygon potentially with holes) with a total of $n$ vertices, and let $A,B$ be two robots, each modeled as an axis-aligned unit square, that can move rectilinearly inside $\mathcal{W}$. The goal is to compute a collision-free motion plan $\boldsymbolπ$, that is, a motion plan that continuously moves $A$ from $s_A$ to $t_A$ and $B$ from $s_B$ to $t_B$ so that $A$ and $B$ remain inside $\mathcal{W}$ and do not collide with each other during the motion. We study two variants of this problem which are focused additionally on the optimality of $\boldsymbolπ$, and obtain the following results. 1. Min-Sum: Here the goal is to compute a motion plan that minimizes the sum of the lengths of the paths of the robots. We present an $O(n^4\log{n})$-time algorithm for computing an optimal solution to the min-sum problem. This is the first polynomial-time algorithm to compute an optimal, collision-free motion of two robots amid obstacles in a planar polygonal environment. 2. Min-Makespan: Here the robots can move with at most unit speed, and the goal is to compute a motion plan that minimizes the maximum time taken by a robot to reach its target location. We prove that the min-makespan variant is NP-hard.
format Preprint
id arxiv_https___arxiv_org_abs_2601_19147
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optimal Motion Planning for Two Square Robots in a Rectilinear Environment
Agarwal, Pankaj K.
de Berg, Mark
Holmgren, Benjamin
Steiger, Alex
Struijs, Martijn
Computational Geometry
Let $\mathcal{W} \subset \mathbb{R}^2$ be a rectilinear polygonal environment (that is, a rectilinear polygon potentially with holes) with a total of $n$ vertices, and let $A,B$ be two robots, each modeled as an axis-aligned unit square, that can move rectilinearly inside $\mathcal{W}$. The goal is to compute a collision-free motion plan $\boldsymbolπ$, that is, a motion plan that continuously moves $A$ from $s_A$ to $t_A$ and $B$ from $s_B$ to $t_B$ so that $A$ and $B$ remain inside $\mathcal{W}$ and do not collide with each other during the motion. We study two variants of this problem which are focused additionally on the optimality of $\boldsymbolπ$, and obtain the following results. 1. Min-Sum: Here the goal is to compute a motion plan that minimizes the sum of the lengths of the paths of the robots. We present an $O(n^4\log{n})$-time algorithm for computing an optimal solution to the min-sum problem. This is the first polynomial-time algorithm to compute an optimal, collision-free motion of two robots amid obstacles in a planar polygonal environment. 2. Min-Makespan: Here the robots can move with at most unit speed, and the goal is to compute a motion plan that minimizes the maximum time taken by a robot to reach its target location. We prove that the min-makespan variant is NP-hard.
title Optimal Motion Planning for Two Square Robots in a Rectilinear Environment
topic Computational Geometry
url https://arxiv.org/abs/2601.19147