An open source and open hardware embedded metric optical flow CMOS camera for indoor and outdoor applications

TLDR

Robust velocity and position estimation at high update rates is essential for mobile robot navigation, yet optical flow sensors based on computer mouse hardware chips, while effective on micro air vehicles, are limited by their high light requirements in typical indoor and outdoor low‑light conditions. The authors present an open‑source, open‑hardware optical flow sensor built around a machine‑vision CMOS image sensor, designed for indoor and outdoor use with very high light sensitivity. Optical flow is estimated on an ARM Cortex‑M4 microcontroller in real time at 250 Hz, with angular‑rate compensation via a gyroscope and distance scaling using an ultrasonic sensor, all performed onboard. The system, designed for extensibility, was demonstrated in‑flight on a micro air vehicle.

Abstract

Robust velocity and position estimation at high update rates is crucial for mobile robot navigation. In recent years optical flow sensors based on computer mouse hardware chips have been shown to perform well on micro air vehicles. Since they require more light than present in typical indoor and outdoor low-light conditions, their practical use is limited. We present an open source and open hardware design 1 of an optical flow sensor based on a machine vision CMOS image sensor for indoor and outdoor applications with very high light sensitivity. Optical flow is estimated on an ARM Cortex M4 microcontroller in real-time at 250 Hz update rate. Angular rate compensation with a gyroscope and distance scaling using a ultrasonic sensor are performed onboard. The system is designed for further extension and adaption and shown in-flight on a micro air vehicle.