Census of bounded curvature paths

TL;DR

This paper develops a method to classify spaces of bounded curvature paths between points, revealing their topological structure and answering a question posed by Dubins about path connectivity.

Contribution

It introduces a simple technology to partition bounded curvature path spaces into parameterized families and classifies their connected components.

Findings

Partition of path spaces into one-parameter families

Classification of connected components by homotopy and isotopy

Resolution of Dubins' question on path space connectivity

Abstract

A bounded curvature path is a continuously differentiable piece-wise $C^2$ path with bounded absolute curvature connecting two points in the tangent bundle of a surface. These paths have been widely considered in computer science and engineering since the bound on curvature models the trajectory of the motion of robots under turning circle constraints. Analyzing global properties of spaces of bounded curvature paths is not a simple matter since the length variation between length minimizers of arbitrary close endpoints or directions is in many cases discontinuous. In this note, we develop a simple technology allowing us to partition the space of spaces of bounded curvature paths into one-parameter families. These families of spaces are classified in terms of the type of connected components their elements have (homotopy classes, isotopy classes, or isolated points) as we vary a parameter defined in the reals. Consequently, we answer a question raised by Dubins (Pac J Math 11(2), 1961).