Pablo Royo

A middleware architecture for unmanned aircraft avionics

An Unmanned Aerial Vehicle is a non-piloted airplane designed to operate in dangerous and repetitive situations. With the advent of UAVs civil applications, UAVs are emerging as a valid option in commercial scenarios. If it must be economically viable, the same platform should implement a variety of missions with little reconfiguration time and overhead. This paper presents a middleware-based architecture specially suited to operate as a flexible payload and mission controller in a UAV. The system is composed of low-cost computing devices connected by network. The functionality is divided into reusable services distributed over a number of nodes with a middleware managing their lifecycle and communication. Some research has been done in this area; yet it is mainly focused on the control domain and in its realtime operation. Our proposal differs in that we address the implementation of adaptable and reconfigurable unmanned missions in low-cost and low-resources hardware.

Requirements, Issues, and Challenges for Sense and Avoid in Unmanned Aircraft Systems

The sense and avoid capability is one of the greatest challenges that has to be addressed to safely integrate unmanned aircraft systems into civil and nonsegregated airspace. This paper gives a review of existing regulations, recommended practices, and standards in sense and avoid for unmanned aircraft systems. Gaps and issues are identified, as are the different factors that are likely to affect actual sense and avoid requirements. It is found that the operational environment (flight altitude, meteorological conditions, and class of airspace) plays an important role when determining the type of flying hazards that the unmanned aircraft system might encounter. In addition, the automation level and the data-link architecture of the unmanned aircraft system are key factors that will definitely determine the sense and avoid system requirements. Tactical unmanned aircraft, performing similar missions to general aviation, are found to be the most challenging systems from an sense and avoid point of view, and further research and development efforts are still needed before their seamless integration into nonsegregated airspace

Wildfire monitoring using a mixed air-ground mobile network

Forest fires are a challenging problem for many countries. They often cause economical lost and ecological damage, and they can sometimes even cost human lives. Finding hot spots immediately after a fire is an important part of fighting forest fires. The main objective is to obtain a temperature map of the burned area, to locate the most critical embers. This information can help firefighter managers make the correct decisions about ground crew movements. The pervasive application described in this article lets firefighters obtain images of hot spots directly from an unmanned aircraft and receive commands from their manager through a communication network. Every firefighter holds a personal electronic device (PED), which includes a touch screen, Wi-Fi connectivity, a GPS receiver, and temperature sensors. Because terrain conditions such as abrupt ravines, rocks, and dense vegetation can introduce obstacles to connectivity, a balloon with a Wi-Fi device is tethered to every firefighters truck to improve communication. In addition, a fixed-wing unmanned aircraft augments the number of communication layers to three. This article studies the quality of this three-layered network in maintaining the applications bandwidth requirements.

Increasing UAV capabilities through autopilot and flight plan abstraction

This paper presents two novel avionics subsystems that aim at overcoming two clearly identified drawbacks of current UAV technology. Firstly, on board exploitation of autopilot telemetry is a complex and autopilot dependent task. Secondly, the flight plan definition mechanism available in most autopilots is just a collection of waypoints. This approach has several limitations, among them its inability to allow interaction between the flight plan and the mission in progress. The Flight Control System Gateway is a component designed to facilitate exploitation of data obtained from the autopilot. It provides a hardware-independent interface that isolates payload components from the autopilot specificities, thus eliminating dependencies on a particular autopilot solution. The Flight Plan Manager is a subsystem that interacts with the FCS Gateway in order to direct the flight of the UAV. It follows a flight plan described via a novel specification mechanism and sends commands to the FCS Gateway for its execution. The specification formalism improves on current mechanisms by introducing higher level constructs and enabling interaction with other payload components. These subsystems are integrated into an overall avionics solution which is based on an innovative publish/subscribe service based software architecture and a LAN based distributed hardware architecture.

Architecture for a helicopter-based unmanned aerial systems wildfire surveillance system

Forest fires are an important problem for many countries. The economical loss is the most visible impact in the short term. The ecological damage and the impact on the wild life diversity and climate change are the most important factors in the long term. Up to now, satellites like NASAs MODIS (moderate-resolution imaging spectroradiometer) system have been the primary source for strategic large area thermal imaging. Tactical monitoring has been until recently reduced to observation from the ground or from some dedicated aerial resource like command and control helicopters. However, little technological support has been available to those in charge of these monitoring tasks. An unmanned aerial systems (UAS) platform capable of overflying the area of a forest fire and with capacity of operating from non-prepared terrains would be an extremely valuable information gathering asset in several well-defined circumstances: surveillance during day and specially night, and early morning or late afternoon monitoring of post-fire hot-spots during the following days of the extinction. This work introduces the Sky-Eye system, a helicopter-based UAS platform that together with its hardware/software architecture is designed to facilitate the development of wildfire remote sensing applications. The Sky-Eye UAS will improve the overall awareness by providing tactical support to wildfire monitoring and control of ground squads. Sky-Eye employs existing commercial off-the-shelf (COTS) technology that can be immediately deployed on the field on-board medium-sized UAS helicopters at a reasonable cost. Sky-Eye is built on top of a user-parameterizable architecture called USAL (UAS Service Abstraction Layer). This architecture defines a collection of standard services and their interrelations as a basic starting point for further development. Functionalities like enhanced flight-plans, a mission control engine, data storage, communications management, etc. are offered.

In-Flight Contingency Management for Unmanned Aerial Vehicles

Contingency analysis and reaction is a critical task to be carried out by any airplane to guarantee its safe operation in a non-segregated airspace. Pilot’s reactions to any kind of incidences that may occur in-flight, like engine malfunctions, loss of electrical power, hydraulic failure, unexpected weather, etc, will determine the fate of the flight. Nowadays, contingency reactions are mainly driven by the airplane manufacturer, with pre-analyzed contingency scenarios covered in the airplane documentation, and by ICAO’s rules as defined in the way flight plans should be prepared and landing alternatives implemented. Flight dispatching is the set of tasks related to flight preparation, such as load and balance, meteorology study and briefing, operational flight planning, contingency analysis and planning, etc. However, managing contingencies on a UAS is a much more complex problem basically due to the automated nature of the vehicle and the lack of situational awareness that pilot’s in command should face. It is well known from the short history of UAS accidents that many of them are directly imputable to pilot errors when trying to manage an unexpected contingency. In this paper we will introduce an structured approach to automate contingency reactions in UAS. Our objective is to classify the contingency sources and up to a certain level abstract their impact on the system operation. Contingencies can be related to four wide aspects of the UAS operation: the flight itself, the mission, the payload, and the awareness systems. depending on the level of severity the contingency reaction may involve changing or canceling mission objectives to canceling the flight itself. In this way, the response to the contingency can be selected from a predefined limited catalog of automated reactions that may reconfigure the UAS operation in all aspects. This structured approximation is only possible because the contingency management is built upon a highly capable architecture called USAL (UAS Service Abstraction Layer) that offers capabilities to properly monitor contingencies and the flexibility to command pre-planned contingency reactions that may affect the flight operation and/or the mission carried out by the system. Contingency management becomes directly dependent upon the UAS dispatching process. USAL provides a dispatching methodology that identified the mission objectives, the UAV airframe and its various characteristics, the software services required for managing the flight and the mission, the sensor and computational payload, etc. All these elements are combined together in an iterative dispatching flow. The result of the process is the actual UAS configuration in terms of fuel, electrical system, payload configuration, flight plan, etc; but also detailed flight plan, alternative routes and landing sites, detailed USAL service architecture and the required contingency planning.

Mission Aware Flight Planning for Unmanned Aerial Systems

The development of Flight Control Systems (FCS) coupled with the availability of other Commercial Off-The Shelf (COTS) components is enabling the introduction of Unmanned Aircraft Systems (UAS) into the civil market. UAS have great potential to be used in a wide variety of civil applications such as environmental applications, emergency situations, surveillance tasks and more. In general, they are specially well suited for the so-called D-cube operations (Dirty, Dull or Dangerous). Current technology greatly facilitates the construction of UAS. Sophisticated flight control systems also make them accessible to end users with little aeronautical expertise. However, we believe that for its successful introduction into the civil market, progress needs to be made to deliver systems able to perform a wide variety of missions with minimal reconfiguration and with reduced operational costs. Most current flight plan specification mechanisms consist in a simple list of waypoints, an approach that has important limitations. This paper proposes a new specification mechanism with semantically richer constructs that will enable the end user to specify more complex flight plans. The proposed formalism provides means for specifying iterative behavior, conditional branching and other constructs to dynamically adapt the flight path to mission circumstances. Collaborating with the FCS, a new module on-board the UAS will be in charge of executing these plans. The paper also presents a prototype implementation of this module and the results obtained in simulations.

Modular avionics for seamless reconfigurable UAS missions

Integrated modular avionics (IMA) architecture is a trend in current avionics that employs a partitioned environment in which different avionics functions share a unique computing environment. UAS avionics, especially in small UAS, are usually of less complexity than not the present on airliners, however, in real autonomous UAS, the onboard avionics should control not only the flight and navigation but also the mission and payload of the aircraft. This involves more complex software as it should implement ldquointelligentrdquo or at least autonomous behavior. This need of both flexibility and complexity management while keeping low costs in the UAS avionics field requires new architectures to cope with. In this article, we describe a modular avionics architecture based on services. The avionics functionality is divided in distributed elements, the services, which are interconnected by a communication middleware. This article also proposes a configuration and deployment infrastructure and its related procedures that complete our vision of UAS avionics.

ISIS+: A Software-in-the-Loop Unmanned Aircraft System Simulator for Nonsegregated Airspace

Unmanned aircraft systems are currently being used primarily for military applications, but with the evolution of avionics technology, a huge market in civil applications is emerging. However, most civil applications require unmanned aircraft systems to access nonsegregated airspace. Current use limitations of nonsegregated airspace make it extremely difficult to extensively evaluate operational concepts and mission profiles. Using real flights to test the complete unmanned aircraft system mission infrastructure involves costs and risks. Therefore, simulators must be used prior to real flight campaigns to test and validate unmanned aircraft system components, and they must take into account all the actors involved in the nonsegregated airspace. This paper describes the development of a software-in-the-loop simulator called ISIS+ to evaluate the automated operations of unmanned aircraft systems in nonsegregated airspace and to test new software components of the unmanned aircraft systems with other avionic...

Flight Plan Specification and Management for Unmanned Aircraft Systems

This paper presents a new concept for specifying Unmanned Aircraft Systems (UAS) flight operations that aims at improving the waypoint based approach, found in most autopilot systems, by providing higher level fligh plan specification primitives. The proposed method borrows the leg and path terminator concepts used in Area Navigation1 (RNAV). Several RNAV leg types are adopted and extended with new ones for a better adaptation to UAS requirements. Extensions include the addition of control constructs that enable repetitive and conditional behavior, and also parametric legs that can be used to generate complex paths from a reduced number of parameters. The paper also covers the design and implementation of a software component that manages execution of the flight plan. To take advantage of current off-the-shelf flight control systems the constructs included in the flight plan are translated to waypoint navigation commands. In this way, the advanced capabilities provided by the flight plan specification language are implemented as a new layer on top of existing technologies. The benefits and the feasibility of the proposed approach for UAS flight plan management are demonstrated by means of a simulated mission that performs the flight inspection of Radio Navigation Aids.