Platform-Independent Geofencing for Low Altitude UAS Operations

Abstract

Small unmanned aircraft systems (UAS) are rapidly proliferating for a variety of commercial and civil applications. Regulators cite detect-and-avoid of manned aircraft as the most significant challenge to integrating small UAS in the National Airspace System. However, most emerging small UAS use cases call for flight within immediate reach of the ground, airspace manned aircraft rarely occupy except on approach or departure. This paper presents a low-altitude geofencing capability for small UAS as a safe alternative to detect-and-avoid. The low-altitude small UAS can be flown manually or through any commercially-available autopilot with the independent geofence unit as a low-cost add-on. The geofencing unit passively monitors the flight, activating as a guidance system override on approach to an altitude or lateral fence boundary. Once active, the geofence turns the UAS back from the border then returns to its monitoring mode. This paper implements geofencing on a small quadrotor flown indoors to eliminate regulatory concerns. While GPS would be a primary means of navigating outdoors, a dual camera, inertial measurement unit, and height sensor package is used to geofence indoors. A Kalman filter integrates sensor data, and a geofence boundary controller overrides the nominal pilot/autopilot guidance inputs to drive the system back within the fenced region. Results show that the fence can be maintained, and that the control authority switch can be done in a stable manner so long as the operator understands when the fence activates and deactivates. Work is ongoing to flight test geofencing outdoors with both multicopter and fixed-wing platforms.

Multi-Mode Guidance for an Independent Multicopter Geofencing System

“…However, to the best of our knowledge, there is no geofencing system available today that addresses issues with single-string avionics and software. This paper investigates the capabilities of an independent geofencing system, extending our previous work, 2,3 and specifically investigates a family of geofencing guidance modes that are compared and constrasted in simulation. A general single-string geofencing and autopilot system is depicted in Figure 1, where the plant and navigation blocks function as they would in any normal multicopter system.…”

“…The idea of using geofencing for airspace safety has been introduced previously, 3-6 and our previous work took steps to develop an initial hardware implementation of keep-in geofencing. 2 The two types of geofences considered in this paper are keep-out and keep-in. Keep-out geofencing prevents UAS from flying over sensitive and high-risk areas such as government buildings, military bases, airports, cities, and stadiums.…”

Small Unmanned Aircraft Systems for Project-Based Engineering Education

“…This quadrotor is also the platform for ongoing research activities. 10 The propulsion system consists of four T-Motor MN-4010 370 kV motors with fully ducted 12 in propellers. The system can carry payloads weighing up to 1 kg with a flight time of approximately 15 minutes.…”

Multiple-Scenario Unmanned Aerial System Control: A Systems Engineering Approach and Review of Existing Control Methods

“…Geofencing is seen as one means of aiding in the sense and avoid issue of UASs, especially small UASs. Stevens et al [141] proposed a geofence system that was platform independent. Many of the small UAS flight controls systems, such as Arduino [142], include a geofence capability inherent in its system that can be utilized for safe operations.…”