Fully Autonomous Indoor Flight Relying on Only Five Very Low-Cost Range Sensors

Abstract

Answering what is the bare minimum combination of avionics and vehicle platform design that enables useful autonomous indoor flight without a Global Positioning System (GPS) is required to understand the lower-cost bounds for indoor unmanned aerial system (UAS) technology. The GTLama indoor UAS, capable of autonomously exploring indoor areas in the GPS-denied environment discussed here, was designed in an attempt to answer this question. TheGTLamaweighs around 600 g (1.3 lb), has a diameter of approximately 70 cm (27.6 in.), and costs less than 900 U.S. dollars. Cost and weight savings are realized through development of an innovative indoor guidance, navigation, and control algorithm that uses only five small off-the-shelf low-cost range sensors rather than expensive and sophisticated sensors such as inertial measurement units, scanning laser range sensors, andGPS. The onboard software leverages the inherent stability of the coaxial rotorcraft platform and fuses information from the low-fidelity range sensors to detect and follow walls and other stationary obstacles. The algorithms are designed to encourage maximum exploration of the perimeter of an indoor environment in a reasonable amount of time. The avionics design and the guidance, navigation, and control algorithms used are discussed in detail and validated through flight tests.