The Dropbot: Design and Development of a Custom Drone for Precision Water Drop Penetration Time (WDPT) Testing

Abstract

Assessing the hydrophobic characteristics of soil is vital for understanding soil wettability or soil-water interactions, particularly in post-wildfire environments where water repellency can significantly impact ecosystem recovery, water infiltration, and erosion control. One key metric in soil wettability studies is the Water Drop Penetration Time (WDPT) test, which evaluates the hydrophobicity of soil and guides land treatment strategies. This thesis presents the design and development of DropBot, a custom-built drone platform engineered for the precise delivery and analysis of water droplets in WDPT tests.The DropBot, a custom drone, integrates a lightweight, 3D-printed frame with a self-leveling platform, enabling consistent droplet deployment and testing across varied terrains. The system is equipped with modular manipulators, a custom droplet release mechanism, and multiple onboard sensors for environmental feedback. The DropBot is operated using the Robot Operating System (ROS) framework, allowing for scalable sensor integration, data acquisition, and autonomous behavior. The development process included iterative mechanical design, sensor calibration, and field testing to ensure precision, stability, and repeatability. Experimental results demonstrate the DropBot’s ability to accurately deliver water droplets with controlled positioning and timing, validating its utility for in-situ WDPT tests. This work also contributes to the growing field of agricultural robotics and sets the stage for further enhancements, such as computer vision integration for surface detection and fully autonomous mission planning for soil property mapping