LOW COST LAGRANGIAN ENVIRONMENTAL WIRELESS SENSOR SYSTEM

Wireless sensor technology is becoming ubiquitous in everyday life. The Low-cost Lagrangian Environmental Sensor System (LLESS) represents an effort to advance the boundaries of scientific flight hardware and mobile wireless sensor networks. LLESS aims to develop a low-cost platform for in-situ sensing of hazardous atmospheric environments such as hurricanes, tornadoes and volcanic eruptions. Broadly speaking, LLESS consists of a “flock” of buoyant motes. Made of Kapton, a mote is a foldable, expandable structure filled with a lifting agent (usually helium). Employing a technique developed at GT, antennas and electronics can be printed on the walls of the structure using ink-jet printers. This mote design leverages current meteorological and RF experience at Georgia Tech Research Institute (GTRI) with existing work by the Georgia Tech ECE department to combine small, lightweight, foldable antenna structures with conventional electronics.

During an actual campaign, motes will be carried aloft by UAVs. When released, the motes allocate themselves at different altitudes within an air column depending on the enclosed volume of gas. Following the prevailing winds, the motes perform lagrangian measurements of their environments as they drift. Endowed with antennas, motes can transfer sensed data between each other, to an airborne gateway (UAV or sounding balloon) or to a ground station. Amongst many applications, the development of LLESS addresses the need for in-situ, distributed natural hazards assessment technology. Eventually, motes are envisioned to be deployed into storm systems and volcanic plumes. Furthermore, the low-cost and simplicity of this foldable “balloon circuit” and printed antenna make this technology attractive for areal distributed surveillance, airborne ad-hoc networks, and will hopefully enable high-resolution atmospheric measurements on future missions to Mars and Titan.

A prototype of a small LLESS network was flown in a multiple weather balloon launch in the summer of 2013. Four balloons were deployed simultaneously during the field experiment. Three of the balloons carried a tethered mote to an altitude of 60,000 feet. These prototype motes contained an array of sensors which measured humidity, pressure, temperature, and magnetic field strength. Additionally, each mote carried a 2.4 GHz radio running ZigBee, allowing them to communicate between each other. The fourth balloon acted as “data mule” or gateway, performing data aggregation from three sensor nodes and relaying their information to the ground over a 900 MHz link. During this presentation, we summarize the performance of this prototype system and describe applications to storm monitoring and hazard mitigation.