A review of the concept of autonomy in the context of the safety regulation of civil unmanned aircraft systems.

Civil aviation safety regulations and guidance mate- rial classify Unmanned Aircraft Systems (UAS) as ei- ther Remotely-Piloted Aircraft Systems (RPAS) or Autonomous Aircraft Systems (AAS). This distinc- tion is based on the premise that the e ective safety risk management of UAS is dependent on the degree of autonomy of the system being operated. However, it is found that there is no consensus on the concept of autonomy, on how it can be measured, or on the na- ture of the relationship between Levels of Autonomy (LoA) and the safety-performance of UAS operations. An objective of this paper is to evaluate existing LoA assessment frameworks for application in avia- tion safety regulations for UAS. The results from a comprehensive review of existing concepts of auton- omy and frameworks for assessing LoA are presented. Six case study UAS were classi ed using the pub- lished LoA frameworks. The implied LoA of UAS for existing modes of operation (e.g., teleoperation, semi- autonomous) were also assessed using the published frameworks. It was found that the existing LoA assessment frameworks, when applied to the case study UAS, do not provide a consistent basis for distinguishing between the regulatory classes of RPAS and AAS. It was also found that the existing regulatory de ni- tion of an autonomous aircraft is too broad, covering UAS of signi cantly di erent levels of capability and system complexity. Within the context of aviation safety regulations, a new LoA assessment framework for UAS is required

Reverse engineering of a fixed wing unmanned aircraft 6-DoF model based on laser scanner measurements

This paper describes a method for deriving sixdegree- of-freedom (6-DoF) aircraft dynamics parameters adopting reverse engineering techniques from three dimensional (3D) laser scanner measurements. In particular, the mass and aerodynamic properties of the JAVELIN Unmanned Aircraft (UA) are determined using accurate measurements from the 3D scanner and successive CAD processing of the geometric data. In order to qualitatively assess the calculated 6-DoF, the trajectory for the spiral mode excited by the engine torque of this UA is simulated and compared to that of a published 6-DoF of the popular AEROSONDE UA which has very similar geometry. Additionally, to further confirm the validity of the approach, the reverse engineering procedure is applied to a published CAD model of the AEROSONDE UA and the associated 6-DoF parameters are calculated. Using these parameters, a spiral descent trajectory is generated using both the published and calculated parameters. The trajectories match closely, providing a good qualitative verification of the reverse engineering method. In future research, the accurate knowledge of the 6-DoF dynamics will enable the development of an Aircraft Dynamics Model (ADM) virtual sensor to augment the UA navigation system in case of primary navigation sensor outages. Additionally, further refinement of the calculated 6-DoF will involve wind tunnel and flight testing activities

Risk-management of UAS robust autonomy for integration into civil aviation safety frameworks

This paper discusses a model of the civil aviation reg-ulation framework and shows how the current assess-ment of reliability and risk for piloted aircraft has a limited applicability for Unmanned Aircraft Systems (UAS) as technology moves towards higher levels of autonomous decision making. Then, a new frame-work for risk management of robust autonomy is pro-posed, which arises from combining quantified mea-sures of risk with normative decision making. The term Robust Autonomy describes the ability of an au-tonomous system to either continue or abort its oper-ation whilst not breaching a minimum level of accept-able safety in the presence of anomalous conditions. The term combines reliability, safety, and robust-ness. The decision making associated with risk man-agement requires quantifying probabilities associated with the measures of risk and also consequences of outcomes related to the behaviour of autonomy. The probabilities are computed from an assessment under both nominal and anomalous scenarios described by faults, which can be associated with the aircraft's ac-tuators, sensors, communication link, changes in dy-namics, and the presence of other aircraft in the op-erational space. The consequences of outcomes are characterised by a loss function quantifies the desir-ability of the outcome

Mutual recognition of national military airworthiness authorities: A streamlined assessment process

The Air and Space Interoperability Council (ASIC) has adopted the European Defence Agency (EDA) process for interregulatory military airworthiness authority recognition. However, there are gaps in the application of this process to nations outside of the European Union. This paper proposes a model that can effectively map diverse technical airworthiness regulatory frameworks. This model, referred to as the Product-Behaviour-Process (PBP) Bow-Tie model, provides the systematic structure needed to represent and compare regulatory frameworks. The PBP Bow-Tie model identifies key points of difference that need to be addressed, during inter-agency recognition between the two regulatory authorities. With the intention to adopt global use of the EDA process, the proposed PBP Bow-Tie model can be used as a basis for the successful recognition of regulatory frameworks outside of the European Union. Iris plots produced from the implementation of this model are presented, and proposed as a suitable means of illustrating the outcome of an assessment, and of supporting the comparisons of results. A comparative analysis of the Australian Defence Force and New Zealand Defence Force airworthiness regulatory frameworks is used as a case study. The case study clearly illustrates the effectiveness of the model in discerning regulatory framework differences; moreover, it has offered an opportunity to explore the limitations of the Iris plot

An innovative navigation and guidance system for small unmanned aircraft using low-cost sensors

Purpose - The purpose of this paper is to design a compact, light and relatively inexpensive navigation and guidance system capable of providing the required navigation performance (RNP) in all phases of flight of small unmanned aircrafts (UA), with a special focus on precision approach and landing. Design/methodology/approach - Two multi-sensor architectures for navigation and guidance of small UA are proposed and compared in this paper. These architectures are based, respectively, on a standard extended Kalman filter (EKF) approach and a more advanced unscented Kalman filter (UKF) approach for data fusion of global navigation satellite systems (GNSS), micro-electro-mechanical system (MEMS)-based inertial measurement unit (IMU) and vision-based navigation (VBN) sensors. Findings - The EKF-based VBN-IMU-GNSS-aircraft dynamics model (ADM) (VIGA) system and the UKF-based system (VIGA+) performances are compared in a small UA integration scheme (i.e. AEROSONDE UA platform) exploring a representative cross-section of this UA operational flight envelope, including high-dynamics manoeuvres and CAT-I to CAT-III precision approach tasks. The comparison shows that the position and attitude accuracy of the proposed VIGA and VIGA+ systems are compatible with the RNP specified in the various UA flight profiles, including precision approach down to CAT-II. Originality/value - The novelty aspect is the augmentation by ADM in both architectures to compensate for the MEMS-IMU sensor shortcomings in high-dynamics attitude determination tasks. Additionally, the ADM measurements are pre-filtered by an UKF with the purpose of increasing the ADM attitude solution stability time in the UKF-based system

Bayesian estimation of diagnostic accuracy of fecal culture and PCR-based tests for the detection of Salmonella enterica in California cull dairy cattle.

Epidemiological studies of low prevalence disease problems are often hindered by the high cost of diagnostic testing. The objective of this study was to evaluate PCR screening of both individual and pooled fecal samples from culled dairy cows for the invA gene of Salmonella followed by culture to determine if the sensitivity and specificity were comparable to the results from traditional culture methods applied to individual samples. Cows from six different dairies were sampled in all four seasons. A total of 240 individual cow fecal samples, 24 fecal pools and 24 pools of 24-hour tetrathionate enrichment broth were tested. Diagnostic sensitivity of PCR screening followed by culture of PCR positive or indeterminate samples (i.e PCR-CUL method) was lower than that of culture (CUL) when applied to individual fecal samples (94.8%, 99.5%), however the specificity was comparable (99.6% and 97.7% respectively). For pools of five fecal samples and pools of five, 24 h tetrathionate broth samples, the specificity of both tests were comparable (∼98%); however, their sensitivity was only comparable in pooled fecal samples (∼93%) but greater for culture compared to PCR-CUL in pooled broth samples (∼99% versus ∼93%). Compared to culture results from testing of individual fecal samples, testing pooled fecal samples by culture had a relative sensitivity of 74% and relative specificity of 96%, testing pooled fecal samples by PCR-CUL resulted in relative sensitivity of 90% and relative specificity of 96%. Testing of pooled 24-hour enrichment broth by PCR-CUL increased the relative sensitivity and specificity to 100%. PCR testing followed by culture of positive or indeterminate samples is a time saving alternative to traditional methods. In addition, pooling of samples may be a useful method for decreasing cost if study aims can accommodate a moderate loss of relative sensitivity

Reverse engineering of a fixed wing unmanned aircraft 6-DoF model for navigation and guidance applications

A method for deriving the parameters of a six-degree-of-freedom (6-DoF) aircraft dynamics model by adopting reverse engineering techniques is presented. The novelty of the paper is the adaption of the 6-DoF Aircraft Dynamics Model (ADM) as a virtual sensor integrated in a low-cost navigation and guidance system designed for small Unmanned Aircraft (UA). The mass and aerodynamic properties of the JAVELIN UA are determined with the aid of an accurate 3D scanning and CAD processing. For qualitatively assessing the calculated ADM, a trajectory with high dynamics is simulated for the JAVELIN UA and compared with that of a published 6-DoF model of the AEROSONDE UA. Additionally, to confirm the validity of the approach, reverse engineering procedures are applied to a published CAD model of the AEROSONDE UA aiding to the calculation of the associated 6-DoF model parameters. A spiral descent trajectory is generated using both the published and calculated parameters of the AEROSONDE UA and a comparative analysis is performed that validates the methodology. The accurate knowledge of the ADM is then utilised in the development of a virtual sensor to augment the UA navigation and guidance system in case of primary navigation sensor outages

ALARP and the risk management of civil unmanned aircraft systems

Key to the continued growth of the civil Unmanned Aircraft System (UAS) aviation sector is the devel- opment of a regulatory framework that will provide assurances in the management of the risks associated with their operation. Decisions in relation the evalu- ation and treatment of aviation risks need to be made in accordance with the As Low As Reasonably Prac- ticable (ALARP) framework. There are a number of concerns in relation to the application of the ALARP framework to new technologies. This paper explores these concerns with respect to the risk management of civil UAS. A review of the ALARP frameworks de ned by the International Civil Aviation Organization (ICAO), the Civil Aviation Safety Authority (Australia), the Civil Aviation Authority (United Kingdom) and by the UK Health and Safety Executive is presented. This review identi ed subtle di erences that can have a signi cant impact on how ALARP frameworks would be applied to UAS. A number of inconsistencies in the frameworks were also identi ed. These issues aside, it was found that a conceptual application of an ALARP framework can be made. However, sig- ni cant diculties were identi ed in the substantia- tion of a framework. In particular, the quanti cation of the decision criteria for UAS, the handling of un- certainty, and the identi cation, characterisation and representation of societal concerns within a frame- work. Guidance as to how the dimensions of societal concern and levels of risk can be jointly considered within an ALARP framework could not be identi ed within the literature. For new technologies such asUAS, these dimensions can be as signi cant a factor in decision-making as that of the quanti ed measures of the risk. Due to these de ciencies, there are signif- icant diculties in the application and substantiation of an ALARP framework to the risk management of new technologies such as UAS

Expanding the Envelope of UAS Certification: What it Takes to Type Certify a UAS for Precision Agricultural Spraying

One of the key challenges to the development of a commercial Unmanned Air-craft System (UAS) market is the lack of explicit consideration of UAS in the current regulatory framework. Despite recent progress, additional steps are needed to enable broad UAS types and operational models. This paper discusses recent research that examines how a risk-based approach for safety might change the process and substance of airworthiness requirements for UAS. The project proposed risk-centric airworthiness requirements for a midsize un-manned rotorcraft used for agricultural spraying and also identified factors that may contribute to distinguishing safety risk among different UAS types and operational concepts. Lessons learned regarding how a risk-based approach can expand the envelope of UAS certification are discussed