Publication

Formulating the unicycle on the sphere path planning problem as a linear time-varying system

Journal Article (2025)

Journal

IEEE Transactions on Robotics

Pages

3335-3347

Volume

41

Doc link

https://doi.org/10.1109/TRO.2025.3567525

File

Download the digital copy of the doc pdf document

Abstract

The kinematics, dynamics, and control of a unicycle moving without slipping on a plane has been extensively studied in the literature of nonholonomic mechanical systems. However, since planar motion can be seen as a limiting case of the motion on a sphere, we focus our analysis on the more general spherical case. This paper introduces a novel approach to path planning for a unicycle rolling on a sphere while satisfying the non-slipping constraint. Our method is based on a simple yet effective idea: first, we model the system as a linear time-varying dynamic system. Then, leveraging the fact that certain such systems can be integrated under specific algebraic conditions, we derive a closed-form expression for the control variables. This formulation includes three free parameters, which can be tuned to generate a path connecting any two configurations of the unicycle. Notably, our approach requires no prior knowledge of nonholonomic system analysis, making it accessible to a broader audience.


Categories

automation, control theory.

Author keywords

Nonholonomic robots, nonholonomic joints, linear time-varying systems, path planning

Scientific reference

F. Thomas and J. Franch. Formulating the unicycle on the sphere path planning problem as a linear time-varying system. IEEE Transactions on Robotics, 41: 3335-3347, 2025.