Evaluation of robust autonomy and implications on UAS certification and design

As the number of potential applications of Unmanned Aircraft Systems (UAS) grows in civilian operations and national security, National Airworthiness Authorities are under increasing pressure to provide a path for certification and allow UAS integration into the national airspace. The success of this integration depends on developments in improved UAS reliability and safety, regulations for certification, and technologies for operational performance and safety assessment. This paper focusses on the latter and describes the use of a framework for evaluating robust autonomy of UAS, namely, the autonomous system’s ability to either continue operation in the presence of faults or safely shut down. The paper draws parallels between the proposed evaluation framework and the evaluation of pilots during the licensing process. It also discusses how the data from the proposed evaluation can be uses as an aid for decision making in certification and UAS designs.

A framework for testing robust autonomy of UAS during design and certification

As the number of Uninhabited Airborne Systems (UAS) proliferates in civil applications, industry is increasingly putting pressure on regulation authorities to provide a path for certification and allow UAS integration into regulated airspace. The success of this integration depends on developments in improved UAS reliability and safety, regulations for certification, and technologies for operational performance and safety assessment. This paper focusses on the last topic and describes a framework for quantifying robust autonomy of UAS, which quantifies the system's ability to either continue operating in the presence of faults or safely shut down. Two figures of merit are used to evaluate vehicle performance relative to mission requirements and the consequences of autonomous decision making in motion control and guidance systems. These figures of merit are interpreted within a probabilistic framework, which extends previous work in the literature. The valuation of the figures of merit can be done using stochastic simulation scenarios during both vehicle development and certification stages with different degrees of integration of hardware-in-the-loop simulation technology. The objective of the proposed framework is to aid in decision making about the suitability of a vehicle with respect to safety and reliability relative to mission requirements.

Assessment of robust autonomy for unmanned systems : progress and challenges

The growing number of potential applications of Unmanned Aircraft Systems (UAS) in civilian operations and national security is putting pressure of National Airworthiness Authorities to provide a path for certification and allow UAS integration into the national airspace. The success of this integration depends not only on developments in improved UAS reliability and safety, but also on regulations for certification, and methodologies for operational performance and safety assessment. This paper focuses on the latter and describes progress in relation to a previously proposed framework for evaluating robust autonomy of UAS. The paper draws parallels between the proposed evaluation framework and the evaluation of pilots during the licensing process. It discusses how the data from the proposed evaluation can be used as an aid for decision making in certification and UAS designs. Finally, it discusses challenges associated with the evaluation.

Visual control for automated aircraft collision avoidance systems

This thesis presents a new vision-based decision and control strategy for automated aircraft collision avoidance that can be realistically applied to the See and Avoid problem. The effectiveness of the control strategy positions the research as a major contribution toward realising the simultaneous operation of manned and unmanned aircraft within civilian airspace. Key developments include novel classical and visual predictive control frameworks, and a performance evaluation technique aligned with existing aviation practise and applicable to autonomous systems. The overall approach is demonstrated through experimental results on a small multirotor unmanned aircraft, and through high fidelity probabilistic simulation studies.

Automatic UAV forced landing site detection using machine learning

The commercialization of aerial image processing is highly dependent on the platforms such as UAVs (Unmanned Aerial Vehicles). However, the lack of an automated UAV forced landing site detection system has been identified as one of the main impediments to allow UAV flight over populated areas in civilian airspace. This article proposes a UAV forced landing site detection system that is based on machine learning approaches including the Gaussian Mixture Model and the Support Vector Machine. A range of learning parameters are analysed including the number of Guassian mixtures, support vector kernels including linear, radial basis function Kernel (RBF) and polynormial kernel (poly), and the order of RBF kernel and polynormial kernel. Moreover, a modified footprint operator is employed during feature extraction to better describe the geometric characteristics of the local area surrounding a pixel. The performance of the presented system is compared to a baseline UAV forced landing site detection system which uses edge features and an Artificial Neural Network (ANN) region type classifier. Experiments conducted on aerial image datasets captured over typical urban environments reveal improved landing site detection can be achieved with an SVM classifier with an RBF kernel using a combination of colour and texture features. Compared to the baseline system, the proposed system provides significant improvement in term of the chance to detect a safe landing area, and the performance is more stable than the baseline in the presence of changes to the UAV altitude.

India’s indigenization of military aircraft design and manufacturing: Towards a fifth-generation fighter

India’s desire to transform itself into an international military power has brought about a rapid shift in its approach to procuring military hardware. The indigenization of India’s military manufacturing capacity forms an integral part of the strategic objectives of Indian military services, with its realization being a function of significant government investment in strategic technologies. This has a number of ramifications. An indigenous Indian military capacity, particularly in the field of aviation, forms a key part of India’s ambition of achieving regional air superiority, or even supremacy, and being capable of power projection. This is particularly in response to China’s increasing presence in South Asian airspace. A burgeoning Indian military manufacturing machine based on a comparative advantage in skilled technicians and lower-cost labour, together with strategic collaboration with foreign military hardware manufacturers, may also lead to neighbouring countries looking to India as a source of competitively priced military hardware. In short, this chapter seeks to analyse the rationale behind India’s attempt to become militarily self-sufficient in the field of aviation, discuss the technical, economic and political context in which it is achieving this transformation, and assess the potential outlook of success for India’s drive to achieve self-sufficiency in the arena of military aviation. This chapter will do so by using the case of India’s attempt to develop a fifth-generation fighter aircraft.

An automated emergency landing system for fixed-wing aircraft: Planning and control

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 re-planning 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 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 manoeuvres to guide the aircraft towards 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 re-plans 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.

Simulation and modelling tools for quantitative safety assessments of unmanned aircraft systems and operations

This paper presents two simple simulation and modelling tools designed to aid in the safety assessment required for unmanned aircraft operations within unsegregated airspace. First, a fast pair-wise encounter generator is derived to simulate the See and Avoid environment. The utility of the encounter generator is demonstrated through the development of a hybrid database and a statistical performance evaluation of an autonomous See and Avoid decision and control strategy. Second, an unmanned aircraft mission generator is derived to help visualise the impact of multiple persistent unmanned operations on existing air traffic. The utility of the mission generator is demonstrated through an example analysis of a mixed airspace environment using real traffic data in Australia. These simulation and modelling approaches constitute a useful and extensible set of analysis tools, that can be leveraged to help explore some of the more fundamental and challenging problems facing civilian unmanned aircraft system integration.

Lung structure and function studied by synchrotron radiation

A novel method for functional lung imaging was introduced by adapting the K-edge subtraction method (KES) to in vivo studies of small animals. In this method two synchrotron radiation energies, which bracket the K-edge of the contrast agent, are used for simultaneous recording of absorption-contrast images. Stable xenon gas is used as the contrast agent, and imaging is performed in projection or computed tomography (CT) mode. Subtraction of the two images yields the distribution of xenon, while removing practically all features due to other structures, and the xenon density can be calculated quantitatively. Because the images are recorded simultaneously, there are no movement artifacts in the subtraction image. Time resolution for a series of CT images is one image/s, which allows functional studies. Voxel size is 0.1mm3, which is an order better than in traditional lung imaging methods. KES imaging technique was used in studies of ventilation distribution and the effects of histamine-induced airway narrowing in healthy, mechanically ventilated, and anaesthetized rabbits. First, the effect of tidal volume on ventilation was studied, and the results show that an increase in tidal volume without an increase in minute ventilation results a proportional increase in regional ventilation. Second, spiral CT was used to quantify the airspace volumes in lungs in normal conditions and after histamine aerosol inhalation, and the results showed large patchy filling defects in peripheral lungs following histamine provocation. Third, the kinetics of proximal and distal airway response to histamine aerosol were examined, and the findings show that the distal airways react immediately to histamine and start to recover, while the reaction and the recovery in proximal airways is slower. Fourth, the fractal dimensions of lungs was studied, and it was found that the fractal dimension is higher at the apical part of the lungs compared to the basal part, indicating structural differences between apical and basal lung level. These results provide new insights to lung function and the effects of drug challenge studies. Nowadays the technique is available at synchrotron radiation facilities, but the compact synchrotron radiation sources are being developed, and in relatively near future the method may be used at hospitals.

质子交换膜燃料电池在无缆水下机器人上的应用研究

质子交换膜燃料电池(PEMFC)作为一种新兴的能源,在汽车和航天器上已经获得成功的应用,本文针对水下环境和PEMFC的特点,对PEMFC在无缆水下机器人(UUV)上试验应用的关键技术进行讨论.

Respiratory syncytial virus infections enhance cigarette smoke induced COPD in mice

Respiratory syncytial viral (RSV) infections are a frequent cause of chronic obstructive pulmonary disease (COPD) exacerbations, which are a major factor in disease progression and mortality. RSV is able to evade antiviral defenses to persist in the lungs of COPD patients. Though RSV infection has been identified in COPD, its contribution to cigarette smoke-induced airway inflammation and lung tissue destruction has not been established. Here we examine the long-term effects of cigarette smoke exposure, in combination with monthly RSV infections, on pulmonary inflammation, protease production and remodeling in mice. RSV exposures enhanced the influx of macrophages, neutrophils and lymphocytes to the airways of cigarette smoke exposed C57BL/6J mice. This infiltration of cells was most pronounced around the vasculature and bronchial airways. By itself, RSV caused significant airspace enlargement and fibrosis in mice and these effects were accentuated with concomitant smoke exposure. Combined stimulation with both smoke and RSV synergistically induced cytokine (IL-1a, IL-17, IFN-c, KC, IL-13, CXCL9, RANTES, MIF and GM-CSF) and protease (MMP-2, -8, -12, -13, -16 and cathepsins E, S, W and Z) expression. In addition, RSV exposure caused marked apoptosis within the airways of infected mice, which was augmented by cigarette smoke exposure. RSV and smoke exposure also reduced protein phosphatase 2A (PP2A) and protein tyrosine phosphates (PTP1B) expression and activity. This is significant as these phosphatases counter smoke-induced inflammation and protease expression. Together, these findings show for the first time that recurrent RSV infection markedly enhances inflammation, apoptosis and tissue destruction in smoke-exposed mice. Indeed, these results indicate that preventing RSV transmission and infection has the potential to significantly impact on COPD severity and progression.

Dynamic cost indexing

This paper describes the development of a generic tool for dynamic cost indexing (DCI), which encompasses the ability to manage flight delay costs on a dynamic basis, trading accelerated fuel burn against ‘cost of time’. Many airlines have significant barriers to identifying which costs should be included in ‘cost of time’ calculations and how to quantify them. The need is highlighted to integrate historical passenger delay and policy data with real-time passenger connections data. The absence of industry standards for defining and interfacing necessary tools is recognised. Delay recovery decision windows and ATC cooperation are key constraints. DCI tools could also be used in the pre-departure phase, and may offer environmental decision support functionality: which could be used as a differentiating technology required for access to designated, future ‘green’ airspace. Short-term opportunities for saving fuel and/or reducing emissions are also identified.

Sectorization: measures and an electromagnetism based approach

Sectorization means dividing a set of basic units into sectors or parts, a procedure that occurs in several contexts, such as political, health and school districting, social networks and sales territory or airspace assignment, to achieve some goal or to facilitate an activity. This presentation will focus on three main issues: Measures, a new approach to sectorization problems and an application in waste collection. When designing or comparing sectors different characteristics are usually taken into account. Some are commonly used, and they are related to the concepts of contiguity, equilibrium and compactness. These fundamental characteristics will be addressed, by defining new generic measures and by proposing a new measure, desirability, connected with the idea of preference. A new approach to sectorization inspired in Coulomb’s Law, which establishes a relation of force between electrically charged points, will be proposed. A charged point represents a small region with specific characteristics/values creating relations of attraction/repulsion with the others (two by two), proportional to the charges and inversely proportional to their distance. Finally, a real case about sectorization and vehicle routing in solid waste collection will be mentioned.

NAV Portugal's performance within the single European Sky Initiative

NAV Portugal is the Air Navigation Service Provider in Portugal, providing air traffic control services in the airspace under the country’s responsibility. Recently, the company has been included in an initiative launched by the European Commission, called the Single European Sky. This aims for a unification of the European airspace, improving it in four main pillars: safety, capacity, environment, and cost-efficiency. To each of them, Key Performance Indicators need to be computed and monitored, all having pre-defined targets. The presented work project will be analyzing how NAV Portugal is doing in the pillar of capacity, proving suggestions if needed.

Global navigation satellite systems e a gestão do espaço aéreo

- Introdução - Sistemas actuais - Galileo - Comparação - Aplicabilidade - Futuro - Referências