Unmanned Aerial Vehicles (UAVs) for civilian applications are in a rapidly growing sector in the global aerospace industry that has only recently begun to gain traction. In this relatively immature field, there is such a steep learning curve that it can be difficult for research groups to begin development of well designed UAV systems. In this chapter, the authors present the AggieVTOL, a modular multi-rotor rotorcraft UAV prototype platform, and an overview of prototyping phase of its development, including design parameters and the implementation of its modular subsystems. Performance results demonstrate the effectiveness of platform.
Top1. Introduction
In recent years, the development of Unmanned Aerial Vehicles (UAVs) has increased dramatically. Largely spearheaded by military applications, UAVs have grown from impractical toys to highly sophisticated tools. While most of the attention has been on military applications, UAVs are expected to play a major role in redefining remote sensing in civilian applications such as traffic control, border patrol, fire fighting management, agricultural monitoring, and natural resource management. However, as with many robotic platforms, UAV development is often slow and expensive. While there is such a demand for UAV systems, each system is often tailored to a specific purpose or a specific architecture which slows down development in the event of application or architecture changes. In this immature field, a prototyping environment is absolutely critical to achieve substantial progress.
The Center for Self-Organizing and Intelligent Systems (CSOIS) at Utah State University has been developing UAVs for the specific emerging field of low cost personal remote sensing. By equipping low cost autonomous UAV systems with scientifically calibrated sensor arrays, end users are able to gather valuable data easily without requiring the hiring of manned aircraft or years of platform specific training. As the field matures, these platforms will be available at such low cost that they will be affordable even to small farm owners wanting to monitor the growth of their crops and water usage on every part of their farm. The goal at the CSOIS is to develop these UAVs in a Cyber-Physical System (CPS) context (Chao 2010, Tricaud 2010); implementing them as a mobile actuator/sensor network to identify, estimate and control a distributed parameter system (DPS), a system where the states evolve over both time and space.
CSOIS’s success with fixed-wing UAVs has led to the development of the AggieAir Flying Circus (“AggieAir Flying Circus,” 2011) service center: a remote sensing operation that specializes in high-resolution, multi-spectral aerial imagery for monitoring soil moisture, riparian and wetland mapping, and fish and wildlife tracking. The low cost platform allows for these applications at a much higher resolution, both temporally and spatially than conventional solutions. The UAV platform, named “AggieAir”, has the capability of carrying multiple cameras that capture imagery in the visual and near-infrared bands at a spatial resolution of 2.5 to 25 cm, depending on the altitude of flight. In Figure 1, the imagery was collected and geo-rectified within 72 hours and given to the Rushing Rivers Institute to be annotated. This type of high resolution imagery is invaluable to researchers and quite often exceeds their expectations.
Figure 1. Annotated mosaic a few days after flight with annotation by Rushing Rivers Institute (“AggieAir Flying Circus,” 2011)
While research continues in the fixed-wing UAV research, development has begun on AggieVTOL; the Vertical Take-Off and Landing (VTOL) rotary wing platform for remote sensing. While rotary wing platforms lack the range of fixed-wing, they have the advantage in maneuverability, from hovering in place with accurate orientation and positioning as well as precise and steady translational movement. The VTOL platform selected for AggieVTOL is known as a Quadrotor, a mechanically simple vehicle with a higher payload capacity compared to other rotorcraft platforms. Specializing in low-altitude, high-resolution imagery of specific targets, AggieVTOL applications includes on-demand spatial data collection and target inspection from multiple angles as well as some of the standard AggieAir fixed-wing UAV applications.