Collision Avoidance Using Spherical Harmonics

TL;DR

This paper introduces a new trajectory planning method using spherical harmonics to efficiently estimate collision-free spaces, enabling real-time, safe navigation even in complex environments.

Contribution

The paper presents a novel optimization-based planner leveraging spherical harmonics for accurate, star-convex shape estimation, improving over heuristic obstacle boundary approximations.

Findings

Performs comparably to existing planners in standard environments.

Surpasses other methods in certain complex scenarios.

Guarantees safety when feasible solutions exist.

Abstract

In this paper, we propose a novel optimization-based trajectory planner that utilizes spherical harmonics to estimate the collision-free solution space around an agent. The space is estimated using a constrained over-determined least-squares estimator to determine the parameters that define a spherical harmonic approximation at a given time step. Since spherical harmonics produce star-convex shapes, the planner can consider all paths that are in line-of-sight for the agent within a given radius. This contrasts with other state-of-the-art planners that generate trajectories by estimating obstacle boundaries with rough approximations and using heuristic rules to prune a solution space into one that can be easily explored. Those methods cause the trajectory planner to be overly conservative in environments where an agent must get close to obstacles to accomplish a goal. Our method is shown to perform on-par with other path planners and surpass these planners in certain environments. It generates feasible trajectories while still running in real-time and guaranteeing safety when a valid solution exists.