Event-Based State Estimation of Planetary Robots using Propeller Sensing

Ravi Kumar Thakur, Luis Granados Segura, Jan Klivan, Radim Spetlik, Tobiáš Vinklárek, Matouš Vrba, Martin Saska

Keywords: Event Camera, Propeller Sensing, Frequency Estimation, Relative Localization

TL;DR: We propose the use event camera for relative state estimation by sensing the propeller of the UAV.

Abstract: Robotic missions for planetary exploration are challenging due to difficult or inaccessible terrain and a limited capability to explore scientific interests beyond the landing zone. The use of Unmanned Aerial Vehicle for such cases offers advantages in terms of high-resolution spatial coverage, support science missions, and terrain mapping to enable planning for ground rovers. This potential can be augmented with the use of a swarm of aerial robots. Such multi-robot system could enable transport of scientific payloads on the planetary surface or mapping of areas inaccessible by rovers and relay orbiters. We propose a framework for relative state estimation for such a system using event-based propeller sensing. The propellers in the event stream are detected, tracked, and sampled asynchronously to extract their rotational frequencies per-propeller. These frequency measurements drive a kinematic state estimation module as a thrust input, while camera-derived position measurements provide the update step. Additionally, we use geometric primitives derived from these event streams to estimate the orientation of the quadrotor using perspective-1-ellipsoid correspondence. We evaluate our approach on a set of real-world outdoor flight sequences obtained from quadrotors in a leader-follower formation, providing a method for decentralized relative localization for multi-robot systems using event cameras.

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Submission Number: 4