Structure-Invariant Range-Visual-Inertial Odometry

TL;DR

This paper presents a novel range-visual-inertial odometry system designed for Mars helicopter missions, capable of accurate navigation over complex, irregular terrain without assuming planar surfaces, by extending the xVIO framework with range data.

Contribution

The work introduces a range-visual-inertial odometry system that prevents scale drift and handles complex terrain, extending existing methods for Mars helicopter navigation.

Findings

Successfully estimates terrain-relative velocity in simulations

Outperforms existing odometry methods in complex terrains

Maintains accuracy without planar terrain assumptions

Abstract

The Mars Science Helicopter (MSH) mission aims to deploy the next generation of unmanned helicopters on Mars, targeting landing sites in highly irregular terrain such as Valles Marineris, the largest canyons in the Solar system with elevation variances of up to 8000 meters. Unlike its predecessor, the Mars 2020 mission, which relied on a state estimation system assuming planar terrain, MSH requires a novel approach due to the complex topography of the landing site. This work introduces a novel range-visual-inertial odometry system tailored for the unique challenges of the MSH mission. Our system extends the state-of-the-art xVIO framework by fusing consistent range information with visual and inertial measurements, preventing metric scale drift in the absence of visual-inertial excitation (mono camera and constant velocity descent), and enabling landing on any terrain structure, without requiring any planar terrain assumption. Through extensive testing in image-based simulations using actual terrain structure and textures collected in Mars orbit, we demonstrate that our range-VIO approach estimates terrain-relative velocity meeting the stringent mission requirements, and outperforming existing methods.