A Custom Gps Recording System for Improving Operational Performance of Aerially-Deployed Herbicide Ballistic Technology

Abstract

Herbicide Ballistic Technology (HBT) is an electro-pneumatic delivery system designed for administering 17.3 mm herbicide-filled projectiles (i.e., paintballs) to visually-acquired weed targets. Currently, HBT is being deployed from a Hughes 500D helicopter platform in aerial surveillance operations to eliminate satellite populations of an invasive weed (Miconia calvescens) in remote watershed areas of East Maui (Hawaii, USA). Coordination and analysis of control operations require that the site of each HBT application be recorded with a handheld GPS data logger. This independent step, though critically important, adds significant time to the target acquisition process where flight time is extremely limited. Furthermore, herbicide use rates are calculated post-operation by rudimentary mean estimation of bulk projectile consumption relative to the number of recorded targets. In an effort to improve operations, GPS and other sensors were integrated directly into the electro-pneumatic device for instantaneously recording time, origin, and trajectory of each projectile discharged. These data are transmitted wirelessly to a custom android application that displays target information in real-time both textually and on a map. The application also records data into a comma delimited file so that it can easily be recalled for map display, or exported to other software such as for conducting additional GIS analysis. Static precision, reported as the Circular Map Accuracy Standard (CMAS) and Spherical Accuracy Standard (SAS), and accuracy, reported as root mean squared error (RMSE) in horizontal and three dimensional space, of the logger are 7.33 m, 11.41 m, 7.27 m and 11.47 m, respectively. Offset reproducibility was determined to be robust based on the convergence of CMAS, from 18.18 m to 3.28 m, and horizontal RMSE, from 12.12 m to 2.86 m, from four different marker positions. Operational data collected over the course of ten operations in 2014 and 2015 agreed with previous anecdotal observations and showed a high level of precision. The logger makes data collection a seamless part of the operation, facilitates logistics of applying airborne HBT, and improves our interpretations of operational HBT performance with more statistically robust measures of herbicide use rate and time-on-target. This provides enhanced capabilities for building operational intelligence relevant to landscape scale invasive species management.