An Automated Emergency Landing System for Fixed‐Wing Aircraft: Planning and Control

Abstract

A number of hurdles must be overcome in order to integrate unmanned aircraft into civilian airspace for routine operations. The ability of the aircraft to land safely in an emergency is essential to reduce the risk to people, infrastructure, and aircraft. To date, few field‐demonstrated systems have been presented that show online replanning and repeatability from failure to touchdown. This paper presents the development of the guidance, navigation, and control (GNC) component of an automated emergency landing system (AELS) intended to address this gap, suited to a variety of fixed‐wing aircraft. Field‐tested on both a fixed‐wing unmanned aerial vehicle (UAV) and Cessna 172R during repeated emergency landing experiments, a trochoid‐based path planner computes feasible trajectories, and a simplified control system executes the required maneuvers to guide the aircraft toward touchdown on a predefined landing site. This is achieved in zero‐thrust conditions with engine forced to idle to simulate failure. During an autonomous landing, the controller uses airspeed, inertial, and GPS data to track motion and maintains essential flight parameters to guarantee flyability, while the planner monitors glide ratio and replans to ensure approach at correct altitude. Simulations show reliability of the system in a variety of wind conditions and its repeated ability to land within the boundary of a predefined landing site. Results from field‐tests for the two aircraft demonstrate the effectiveness of the proposed GNC system in live operation. Results show that the system is capable of guiding the aircraft to close proximity of a predefined keyhole in nearly 100% of cases.

Embedded Computation Architectures for Autonomy in Unmanned Aircraft Systems (UAS)

“…For instance, embedded architectures either based on micro controllers or ARM processors such as a Cortex M7 in Pixhawk4 [ 25 ] are commonly used for low level tasks. In the case of high level tasks, it is common to find pc104 [ 26 ], mini/nano-itx/Raspberry Pis or any other small form-factor PC architecture.…”

Ground impact probability distribution for small unmanned aircraft in ballistic descent

“…An study on the impact area for a general uncontrolled descent, including a buffer zone, is presented in [21]. A method for automatically finding a proper landing area for an aircraft in emergency descent is shown in [38], [37], and the ability of a fixed wing aircraft to glide to a designated emergency landing area is presented in [11]. In [2] a method for determining a no-thrust flight trajectory to reach a particular landing spot is presented.…”

The Value of Step-by-Step Risk Assessment for Unmanned Aircraft

“…Metrics for safety, including hazard metrics and risks metrics are presented in [17], in [18] a software safety case is developed, and in [19] a generic safety case is presented based on experience with NASA unmanned aircraft missions. A method for automatically finding a proper landing area for an aircraft in emergency descent is shown in [20], [21], and the ability of a fixed wing aircraft to glide to a designated emergency landing area is presented in [22]. In [23] a study for ground impact fatalities resulting from power failure and subsequent uncontrolled glide is presented.…”