Unmanned Aircraft Systems Operations Research Articles

無人航空機の運航技術における課題と展望(後編) : 空域/ATMにおける技術課題・国際動向・国内動向

無人航空機の運航技術における課題と展望(後編) : 空域/ATMにおける技術課題・国際動向・国内動向

Ranges of Injury Risk Associated with Impact from Unmanned Aircraft Systems

Regulations have allowed for increased unmanned aircraft systems (UAS) operations over the last decade, yet operations over people are still not permitted. The objective of this study was to estimate the range of injury risks to humans due to UAS impact. Three commercially-available UAS models that varied in mass (1.2–11 kg) were evaluated to estimate the range of risk associated with UAS-human interaction. Live flight and falling impact tests were conducted using an instrumented Hybrid III test dummy. On average, live flight tests were observed to be less severe than falling impact tests. The maximum risk of AIS 3+ injury associated with live flight tests was 11.6%, while several falling impact tests estimated risks exceeding 50%. Risk of injury was observed to increase with increasing UAS mass, and the larger models tested are not safe for operations over people in their current form. However, there is likely a subset of smaller UAS models that are safe to operate over people. Further, designs which redirect the UAS away from the head or deform upon impact transfer less energy and generate lower risk. These data represent a necessary impact testing foundation for future UAS regulations on operations over people.

無人航空機の運航技術における課題と展望(前編) : 通信・操縦方式・衝突回避における技術課題

無人航空機の運航技術における課題と展望(前編) : 通信・操縦方式・衝突回避における技術課題

Landing Site Reachability in a Forced Landing of Unmanned Aircraft in Wind

Autonomous contingency management systems, such as a forced-landing system, which reacts appropriately to an engine failure, are important for the safe operation of unmanned aircraft systems. This paper details a method to ascertain the reachability of any possible emergency landing site for a forced landing in steady uniform wind conditions. With knowledge of the aircraft’s state, such as speed, heading, location, and orientation of a landing site, a method to calculate a minimum height loss path is developed based on aircraft glide performance. Wind direction and speed are taken into account using a trochoidal approach by defining the minimum height loss turn path. To facilitate real-time implementation, simplified gliding equations are developed without accuracy loss. The reachability of each site can be calculated as well as how much safety margin an aircraft would have. This method is generic and could also provide decision support for human pilots in forced-landing situations. Two types of aircraft, the Airbus A320-400 and the Cessna 172, have been investigated to demonstrate the usefulness of the method, using Monte Carlo simulations in a synthetic X-Plane simulation environment, to demonstrate the performance and effectiveness of the proposed approaches.

O.R.C.U.S. risk assessment tool for operations of light UAS above Germany

PurposeThe purpose of this paper is to discuss European Aviation Safety Agency’s (EASA’s) Prototype Regulation on Unmanned Aircraft Operation and introduce the tool Operational Risk Considerations for Unmanned Aircraft Systems (O.R.C.U.S.). In contrast to existing airworthiness regulations for civil manned aircraft, EASA’s approach is focussed on flight operations and not aircraft, a significant change for the domain of civil airworthiness.Design/methodology/approachO.R.C.U.S. is a software risk analysis tool developed by the corresponding author. It encompasses all relevant factors for flight operations of light Unmanned Aircraft Systems (UAS) above populated areas in Germany. The tool generates predictions of possible fatalities in the event of a light Unmanned Aircraft crash through the use of validated statistics and considering the time and location of a mission. An example mission, including a discussion of the results, is provided to demonstrate and discuss the capabilities of O.R.C.U.S.FindingsEASA’s Prototype Regulation on Unmanned Aircraft Operation makes a sound risk assessment of UAS flight operations indispensable. O.R.C.U.S. is able to increase risk awareness for operators and airworthiness authorities even if only less to none information about the UAS is available, supporting the possible approval of such an operation.Originality/valueIn this paper, O.R.C.U.S. is presented for the first time. O.R.C.U.S. can provide risk estimations for UAS operations in Germany, even if only minimum information about the UAS is available. In contrast to other tools, O.R.C.U.S. offers a unique risk prediction by combining aspects of the flying Unmanned Aircraft as well as the overflown area.

Evaluating Methods of FAA Regulatory Compliance for Educational Use of Unmanned Aircraft Systems (UAS)

Educational institutions on all levels of the educational spectra are interested in integrating unmanned aircraft systems into their curricula; however, complex Federal Aviation Administration (FAA) regulations and potential liability issues may deter some institutions from proceeding. Using document analysis of FAA regulations, legal interpretations, and precedent, the researchers codify and compare the methods by which educational entities can legally comply with the FAA’s UAS regulations. This research overviews key issues with each method of compliance, including UAS flown as: a Public Aircraft Operation, under a Public Law 112-95 Section 333 Exemption, for hobby and recreational purposes under Public Law 112-95 Section 336 Model Aircraft Rules, and in compliance with the newly released 14 CFR Part 107 Regulations. The researchers present a recommended decision matrix for educational entities to evaluate their individual operational needs and select the most appropriate method of regulatory compliance for UAS integration. Additionally, the researchers present a proposed framework for an institutional review committee to evaluate and safely implement UAS operations at educational campuses.

Sense and avoid for unmanned aircraft systems

Sense and avoid (SAA) represents one of the main roadblocks to the integration of unmanned aircraft systems (UAS) operations by aviation authorities around the world. This tutorial outlines and reviews the substantial breadth of SAA architectures, technologies, and algorithms. Starting from a discussion about what constitutes a UAS and how it is different than manned aircraft, basic SAA definitions and taxonomies are discussed. The SAA process is dissected into three fundamental tasks, defined as sensing, detecting, and avoiding, which are discussed in detail. The tutorial concludes with a summary of the regulatory and technical issues that continue to challenge the progress on SAA, as a key component of reliable UAS operation in civil aviation authorities (CAAs) around the world.

Seeing the Threat: Pilot Visual Detection of Small Unmanned Aircraft Systems in Visual Meteorological Conditions

One key challenge of integrating Unmanned Aircraft Systems (UAS) platforms into the National Airspace System (NAS) is the potential for midair collisions between manned aircraft and the unmanned system. The lack of an established UAS benchmark for Detect, Sense & Avoid Systems put the preponderance of avoidance efforts on manned aircraft pilots to visually see and avoid potential collision threats. The small size, unusual configurations, and diverse operational applications of unmanned systems make UAS platforms difficult to visually identify. This paper sought to determine the mean visibility distance of small UAS systems (sUAS) to an alerted pilot flying a general aviation aircraft in visual meteorological conditions (VMC). The study evaluated mean visibility distance to various sUAS platforms based on a scripted set of UAS convergence conditions. The study utilized a mixed method design in which a general aviation aircraft was flown into a UAS operations area. Study pilots were instructed to locate a flying UAS aircraft without bearing assistance. Both the UAS and manned aircraft were assigned vertically de-conflicted altitudes with the UAS aircraft executing a series of converging and crossing courses relative to the manned aircraft. The distance at which the pilot visually located the UAS platform was timestamped and electronically recorded via a GPS tracking device. The various conditions were analyzed to determine significant visibility differences among the various convergence conditions. Qualitative data was collected from participant comments and observations recorded by an in-flight safety observer.

Feature article: proof-of-concept airborne sense and avoid system with ACAS-XU flight test

Today, unmanned aircraft system (UAS) operations are typically conducted in segregated airspace and in limited combat theaters. In order to integrate UAS into the National Airspace System (NAS), UAS must operate safely, efficiently, and be compatible with existing manned aircraft traffic so that the overall safety and efficiency of the airspace is not degraded [1]. There are many challenges that lie ahead to allow UAS unrestricted access to NAS, but perhaps the greatest technical challenge involves fulfilling the See and Avoid requirements (14CFR 91.111 and 91.113).

Unmanned aircraft systems in the national airspace system

As the technological and operational capabilities of unmanned aircraft systems (UAS) have grown, so too have international efforts to integrate UAS into civil airspace. However, one of the major concerns that must be addressed in realizing this integration is that of safety. For example, UAS lack an on-board pilot to comply with the legal requirement that pilots see and avoid other aircraft. This requirement has motivated the development of a detect and avoid (DAA) capability for UAS that provides situational awareness and maneuver guidance to UAS operators to aid them in avoiding and remaining well clear of other aircraft in the airspace. The NASA Langley Research Center Formal Methods group has played a fundamental role in the development of this capability. This article gives a selected survey of the formal methods work conducted in support of the development of a DAA concept for UAS. This work includes specification of low-level and high-level functional requirements, formal verification of algorithms, and rigorous validation of software implementations.

Synthesis of Unmanned Aircraft Systems Safety Reports

The proliferation and extension of unmanned aircraft systems from military to civil and public use applications has rapidly outpaced the safety analysis that is normally associated with the introduction of a new and novel aircraft. Insights into the types of anomalous events associated with accidents and incidents involving civil and public use unmanned aircraft systems operating in the National Airspace System were derived from an information synthesis of archival, publically available reports from the Aviation Safety Information and Analysis Sharing system. The vast majority of anomalous events were related to equipment failures, primarily lost link, distantly followed by a variety of non-equipment-related events involving pilot/operator errors, such as near-mid-air collisions, altitude deviations, airspace violations, and procedural deviations. The identification of types of anomalous events associated with safety reports provided insights for consideration when developing and implementing mitigation strategies for the design, training, and operation of unmanned aircraft systems.

Structuring the safety case for unmanned aircraft system operations in non-segregated airspace

Routine access to non-segregated airspace is a key enabler for the civilian Unmanned Aircraft System (UAS) industry. Approvals for UAS operations in this airspace are contingent on the provision of a safety case, which details how the risk of a Mid-Air Collision (MAC) accident will be managed to an acceptable level. There is no accepted framework for structuring operational safety cases for UAS and this gives rise to a number of challenges to the application of the regulation by “safety target” approach. Further, a wide range of controls has been proposed for mitigating the risk, however the effectiveness of the controls is not known. A reconciliation and extension of existing causal models describing the MAC accident sequence is provided in this paper. A barrier bow tie model is developed as a means for structuring the safety case for generic UAS operations in non-segregated airspace. The model is applied to the classification of over 50 commonly used risk controls and the relationship between the control and the manner in which the reduction in MAC risk is achieved is determined. A case-study application is also presented validating the utility of the tool in the development and communication of safety cases for UAS operations in civilian airspace.

Ground-Based Sense and Avoid: Enabling Local Area Integration of Unmanned Aircraft Systems into the National Airspace System

As unmanned aircraft systems (UAS) become more important to the US military and other users, the pressure to allow them to fly in the national airspace increases. The greatest impediment to this is the lack of an alternative means of compliance with federal “see and avoid” regulations to provide the capability to avoid airborne conflicts between the UAS and manned aircraft. To provide this alternative means of compliance, the US Army is leading the development of a Ground-Based Sense and Avoid System (GBSAA). The system uses ground-based radars, threat detection and alerting logic, and decision support display aids to provide an air picture of the UAS’s operating environment and follows the DO-254 and DO-178C standards for safety critical avionics hardware and software, respectively. This system will allow greater airspace access and lower cost operations by replacing ground observers in the field with a centralized system, thus consolidating the observer function. The first GBSAA deployment site is expected to go live in 2016 at Fort Hood Army Air Field, Fort Hood, TX, operating under the FAA’s Certificate of Authorization process. This paper provides an overview of the system and of a human-in-the-loop simulation-based test exercise that is a key component of the certification of the system. During this test exercise, 19 self-separation violations, in which intruders came within 1 nmi horizontally and 100 ft vertically of the ownship, and no near-mid-air collisions (NMACs) occurred during 195 hours of simulation, including many stressing multi-intruder scenarios, during which reported workload was low and situation awareness was high throughout. All participants ultimately stated that the GBSAA system was appropriate for UAS operations within the National Airspace System (NAS).

Effect of time pressure and target uncertainty on human operator performance and workload for autonomous unmanned aerial system

Autonomous unmanned aircraft systems (UAS) are being utilized at an increasing rate for a number of military applications. The role of a human operator differs from that of a pilot in a manned aircraft, and this new role creates a need for a shift in interface and task design in order to take advantage of the full potential of these systems. This study examined the effects of time pressure and target uncertainty on autonomous unmanned aerial vehicle operator task performance and workload. A 2 × 2 within subjects experiment design was conducted using Multi-Modal Immersive Intelligent Interface for Remote Operation (MIIIRO) software. The primary task was image identification, and secondary tasks consisted of responding to events encountered in typical UAS operations. Time pressure was found to produce a significant difference in subjective workload ratings as well as secondary task performance scores, while target uncertainty was found to produce a significant difference in the primary task performance scores. Interaction effects were also found for primary tasks and two of the secondary tasks. This study has contributed to the knowledge of UAS operation, and the factors which may influence performance and workload within the UAS operator. Performance and workload effects were shown to be elicited by time pressure. Relevance to industry: The research findings from this study will help the UAS community in designing human computer interface and enable appropriate business decisions for staffing and training, to improve system performance and reduce the workload.

Unmanned and Uncontrolled: The Commingling Theory and the Legality of Unmanned Aircraft System Operations

In 2002 Australia became the first nation to promulgate certification standards for the commercial use of drones or Unmanned Aircraft Systems (UAS). Since that time the Australian Civil Aviation Safety Authority (CASA) has played a key role both domestically and internationally through the International Civil Aviation Organization (ICAO) in assisting to develop technical guidance materials that will enable contracting states to develop UAS regulations. An arduous component of this task is the fact that all existing aircraft are capable of being unmanned. Moreover, given the unbounded nature of aircraft operations, UAS regulations necessarily require international harmonisation. But the objective of developing universal UAS standards is still far from being finalised while the accelerating pace of UAS technological development continues to challenge traditional regulatory regimes and legal systems throughout the world. This paper considers the broader legal issues associated with civilian UAS operations and their integration into unsegregated civilian airspace. In particular the Australian UAS regulatory experience is examined with some unique constitutional limitations identified in relation to the application of the so-called ‘commingling theory’. It is contended that such limitations may render void existing UAS regulation in certain situations – many of which are likely to have adverse privacy implications. This paper strongly asserts that if the commercial benefits attendant to UAS operations is to be fully realised then their risks to society must be controlled through domestic legislation that is harmonised with internationally agreed standards.

Lost in Debate: The Safety of Domestic Unmanned Aircraft Systems

The United States is poised to integrate commercial unmanned aircraft systems (UAS) into the national airspace and enable government entities to use UAS in a more expedient manner. This policy change, mandated by the Federal Aviation Administration (FAA) Modernization and Reform Act of 2012, offers new economic, social and scientific opportunities as well as enhanced law enforcement capacity. However, such benefits will be accompanied by concerns over misuse and abuse of the new technologies by criminals and terrorists. Privacy has been the focus of public debate over the more widespread use of UAS. This paper examines a variety of issues related to allowing broad UAS operations in domestic airspace, and puts forth that safety should be the top priority of policy makers in their effort to integrate UAS into the national airspace system. This article is available in Journal of Strategic Security: http://scholarcommons.usf.edu/jss/vol7/iss4/5

Politics & technology: U.S. polices restricting unmanned aerial systems in agriculture

Many industry observers foresee that agriculture worldwide is posed to substantially benefit from the use of unmanned aircraft systems (UASs), commonly known as drones. Industry special interests predict that 80% of domestic sales of UASs in the U.S. will be for agriculture. However, some fear that the public anxiety of the UAS operating in U.S. airspace could stall their introduction, a move that would potentially place some of American farmers’ production practices at an economic disadvantage. Currently, this public policy controversy is influencing UAS integration into U.S. agriculture, with the potential of spilling over internationally.This project examines the nature of the current debate surrounding the UAS within the U.S., analyzes the impact on agriculture from the legislation considered, discusses policy options to ameliorate the controversy, and describes the factors that will likely determine UAS operations within the U.S. The information was obtained from government documents, academic research, industry studies, nonprofit organizations, and media reports. An analysis was done using these data on how UAS legislation may affect agriculture.Popularized images of the silent-kills overseas using militarized UASs, safety concerns, and a fear of privacy invasions were found to generate intense opposition to their domestic integration. Spurred by the FAA’s congressional mandate to fully integrate UASs into the nation’s airspace, a significant number of bills, particularly in state legislatures, have been introduced in an attempt to regulate UAS use. Although geared toward privacy protection and law enforcement, some laws may adversely affect agriculture because they create legal uncertainty and/or they sweepingly ban or highly curtail local UAS operations. Possible solutions have been proposed: (1) reducing the legal uncertainty regarding UASs, (2) adopting an industry Code of Conduct and Safe Practices, and (3) producing a consensus on UAS regulations among diverse groups through an open discussion of how to balance UAS operations with safeguards on privacy and property rights. The perceived economic potential of the UAS, particularly in agriculture, combined with the lobbying power of the UAS industry, strongly suggest that policy will eventually be developed that will allow the use of this technology for agriculture in U.S. airspace.

Experimental Determination of Low-Cost Servomotor Reliability for Small Unmanned Aircraft Applications

One of the key challenges of designing low-cost Unmanned Aircraft Systems (UAS) is to ensure acceptable and certifiable reliability factors for the adopted Commercial-off-the-Shelf (COTS) components since their reliability is often not quantified. In this paper, the experimental results obtained for quantifying the reliability of mini Unmanned Aircraft (UA) servomotors (by recording their time-to-failure on a defined set of test runs) are presented. The Weibull prediction model is adopted for quantitative analysis and the associated key mathematical models. The methodology adopted for performing the reliability analysis including the test bench setup used for the experiments is described. The results indicate a level of reliability expected for low-cost servos. Such servos could be used for low-risk UAS operations (e.g. small UA operating over sparsely populated regions) and where the economics of the business case permitted higher loss rates.

Survey of Operators’ Unmanned Aircraft Systems Experience

The routine integration of unmanned aircraft systems (UAS) into controlled airspace is a pressing challenge around the world. In order to identify what information surveillance systems need to detect and display about the UAS, air traffic controllers and pilots were surveyed. Participants were asked a wide range of questions regarding their experience with UAS and information requirements under different conditions. This paper focuses on understanding operators’ previous experiences with UAS. Close to 60% of controllers and 42% of pilots reported having had some form of experience with UAS. Approximately the same proportion of controllers reported UAS operating in airspace designated for UAS operations as those reporting operations in low and high density regions of airspace and near standard flows in their airspace.

Sense and avoid requirements for unmanned aircraft systems using a target level of safety approach.

One of the most critical challenges to full integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS) is the requirement to comply with CFR 14 Part 91.113 to "see and avoid" other aircraft. Various attempts have been made to develop systems to "sense and avoid" other aircraft so UAS can comply with the intent of the regulation. This article proposes a framework to develop effectiveness requirements for any SAA system by linking UAS characteristics and operating environments to midair collision risk quantified by a fatality rate. The framework consists of a target level of safety (TLS) approach using an event tree format. Safety has been identified as the most important consideration in the UAS integration process. While safety can be defined in many ways, the authors propose using a fatality rate metric that follows other statistics used in the industry. This metric allows for the use of a TLS approach to the development of SAA requirements for system certification. Failure to adequately link system requirements to safety could result in the implementation of SAA systems that either do not adequately mitigate the risk associated with UAS operations or are overdesigned, resulting in increased cost and complexity. This article demonstrates the use of the proposed framework to develop specific SAA effectiveness standards based on UAS weight and airspace class combinations.