I. INTRODUCTION
The problem of detecting gases and mapping their concentration is relevant to different applications, such as gas
leak detection in industrial areas, surveillance of areas where
hazardous gases might be present and pollution monitoring
in cities. In the past decades, stationary sensor networks
have been largely used to address this problem. Typically,
the sensors used are relatively inexpensive, readily available
and light weight, but they have to be directly exposed to
the target gases (i.e., in-situ sensing), which means that they
provide a point measurement where they are positioned [1].
The nature of the sensors used entails that gas emissions
could go undetected due to sparse measurements and that,
whenever there are changes to the environment where the
network is placed, a new, time-consuming deployment could
be required.
More recently, mobile robots equipped with gas sensors
have proven to be valuable instruments for gas detection
and mapping [2], [3], as they can flexibly adapt to complex
outdoor and indoor environments. Moreover, their use has become even more appealing since the introduction of sensors
which are capable of detecting gases remotely. For instance,
sensors based on tunable diode laser absorption spectroscopy
(TDLAS) [4] allow for ranged sensing up to considerable
distances. However, compared to in-situ sensors, they are
larger and more expensive. Thus, they cannot be distributed
in large numbers in the environment, but they are suitable to
be used on-board a mobile platform