Thanks to recent advances in micro-technology, drone manufacturers have been able to develop nano air vehicles (NAVs) or nano-drones; with insect-sized aircrafts expected in the future. NAVs are extremely small, with a wingspan lower than 15 cm, and weight lower than 50 g. Their tiny form-factor and maneuverability allow sensing of hazardous environments inaccessible to terrestrial robots and larger drones, can fly over areas being unobserved, and are not a hazard for humans, enabling their use in public areas or inside buildings. Providing a NAV with olfaction capabilities is now possible due to miniaturization and low-cost fabrication of gas sensors. A smelling NAV (SNAV) could be used in a myriad of applications that range from environmental monitoring to search and rescue, leak detection, chemical, biological, radiological and nuclear (CBRN) defense, explosive finding, among others. For example, to search for victims and gas leaks inside pockets that form within the wreckage of collapsed buildings in the aftermath earthquakes or explosions. SNAVs can navigate such scenarios much faster than a terrestrial robot, passing through confined spaces that preclude human entry, evading obstacles or large gaps and sampling the space in three dimensions (3D).
We have developed a SNAV prototype and experimentally evaluated its performance in challenging scenarios. In this paper, we describe the technical details of the prototype, and a series of experiments to evaluate its feasability for indoor gas source localization and mapping. We also assessed the impact of the propellers on the chemical sensor signals. The SNAV was able to build a 3D gas distribution map of the environment (160 m2) in less than 3 minutes, and localize the emission source with errors of ~ 1 m.