Towards the Determination of Safe Operating Envelopes for Autonomous UAS in Offshore Inspection Missions

From MDPI via Jisc Publications RouterHistory: accepted 2021-07-21, pub-electronic 2021-07-28Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; Grant(s): EP/R026173/1A drive to reduce costs, carbon emissions, and the number of required personnel in the offshore energy industry has led to proposals for the increased use of autonomous/robotic systems for many maintenance tasks. There are questions over how such missions can be shown to be safe. A corollary exists in the manned aviation world for helicopter–ship operations where a test pilot attempts to operate from a ship under a range of wind conditions and provides subjective feedback on the level of difficulty encountered. This defines the ship–helicopter operating limit envelope (SHOL). Due to the cost of creating a SHOL there has been considerable research activity to demonstrate that much of this process can be performed virtually. Unmanned vehicles, however, have no test pilot to provide feedback. This paper therefore explores the possibility of adapting manned simulation techniques to the unmanned world to demonstrate that a mission is safe. Through flight modelling and simulation techniques it is shown that operating envelopes can be created for an oil rig inspection task and that, by using variable performance specifications, these can be tailored to suit the level of acceptable risk. The operating envelopes produced provide condensed and intelligible information regarding the environmental conditions under which the UAS can perform the task

Yttrium doped ZnO nanorod arrays for increased charge mobility and carrier density for enhanced solar water splitting

An innovative procedure is presented, when for the first time, yttrium doped ZnO vertically aligned nanorods have been synthesized using a unique rapid microwave assisted method. In comparison with pristine ZnO NRs, the Y-doped samples present more favourable morphology along with reduced crystallinity due to substitutional defects, YZn. The Y acted as a shallow donor type defect, leading to an 80% increase in dopant density, to 1.36×1018 cm−2 in the 0.15% Y sample. The transmission line model was used to analyse the transport properties. It was found that a 1000-fold increase in conductivity and electron mobility was achieved by doping 0.15% Y, resulting in a high density of donors which fill charge traps. Meanwhile, a significant improvement in conductivity was accompanied by greater electron hole recombination and band gap reduction. Analysis of photoluminescence spectra reveals the effect of Y doping on native point defects, initially reducing Zn2+ vacancies by filling with YZn, followed by the reduction of O2- vacancies with interstitial doping at higher Y concentration. With a fine balance of superior conductivity and charge recombination rate, the photocatalytic water splitting performance was optimised achieving photocurrent of 0.84 mA cm−2 at 1.23 VRHE with 0.1% Y doping. This corresponded to a 47% enhancement in photoconversion efficiency compared to the pristine sample

Case studies to illustrate the rotorcraft certification by simulation process; CS 27/29 dynamic stability requirements

© The AuthorsThis paper is one of a set presented at the 49th European Rotorcraft Forum displaying results from the EU Clean Sky 2 project, Rotorcraft Certification by Simulation (RoCS). The process developed by the RoCS team provides guidance on the requirements for the use of simulation in certification and features four case studies that illustrate aspects of the process applied using flight simulation models and flight test data provided by Leonardo Helicopters. This paper presents the case study on Dynamic Stability, for the relevant certification paragraphs in the EASA Certification Specifications CS-27 and CS-29. The Dynamic Stability paragraphs from the Specifications are described and results from simulation model fidelity assessment, and updating compared with test data, are presented for a reference flight condition. The credibility of extrapolations of the flight simulation model results to conditions at higher altitude, different airspeeds and vertical rates of climb are then discussed. Preliminary results from piloted simulation trials, with a ‘new’ flight test manoeuvre, are included to illustrate flight simulator fidelity assessment methods and to explore the veracity of the stability margins set by the Certification Specifications

Case studies to illustrate the rotorcraft certification by simulation process; CS 29/27 low-speed controllability

© The AuthorsThis paper is one of a set presented at the 49th European Rotorcraft Forum discussing results from the EU Clean Sky 2 project, Rotorcraft Certification by Simulation (RoCS). The process developed by the RoCS team provides guidance on the use of flight simulation in certification and features four case studies that illustrate aspects of the process using flight simulation models and flight test data provided by Leonardo Helicopters. This paper presents the case study for the low-speed controllability requirements from the relevant certification paragraphs in the EASA Certification Specifications CS-27 and CS-29. Following an introduction of the related specifications, and the motivation behind seeking compliance supported by simulation, the various phases of the RCbS process are explored in more detail. The intent is to exercise aspects of the RoCS guidance in a practical application to investigate the implementation, and the strengths and limitations, given real-world constraints. Emphasis is placed on the Validation & Verification as well as the Credibility Assessment, taking into account test and simulation uncertainties. Results from piloted simulation trials are included to illustrate possible flight simulator fidelity assessment methods

Case Studies to Illustrate the Rotorcraft Certification by Simulation Process; CS27/29 Dynamic Stability Requirements

This paper is one of a set presented at the 49th European Rotorcraft Forum displaying results from the EU Clean Sky 2 project, Rotorcraft Certification by Simulation (RoCS). The process developed by the RoCS team provides guidance on the requirements for the use of simulation in certification and features four case studies that illustrate aspects of the process applied using flight simulation models and flight test data provided by Leonardo Helicopters. This paper presents the case study on Dynamic Stability, for the relevant certification paragraphs in the EASA Certification Specifications CS-27 and CS-29. The Dynamic Stability paragraphs from the Specifications are described and results from simulation model fidelity assessment, and updating compared with test data, are presented for a reference flight condition. The credibility of extrapolations of the flight simulation model results to conditions at higher altitude, different airspeeds and vertical rates of climb are then discussed. Preliminary results from piloted simulation trials, with a new flight test manoeuvre, are included to illustrate flight simulator fidelity assessment methods and to explore the veracity of the stability margins set by the Certification Specifications

Case studies to illustrate the rotorcraft certification by simulation process; CS 29/27 category A rejected take-off, confined area

© The AuthorsThis paper is one of a set presented at the 49th European Rotorcraft Forum discussing results from the EU Clean Sky 2 project, Rotorcraft Certification by Simulation (RoCS). The process developed by the RoCS team provides guidance on the use of flight simulation in certification and features four case studies that illustrate aspects of the process applied using flight simulation models and flight test data provided by Leonardo Helicopters. This paper presents the case study for Rejected Take-Off (RTO): Category A in a Confined Area, for the relevant certification paragraphs in the EASA Certification Specifications CS-27 and CS-29. The relevant paragraphs from the Specifications are described and results from simulation model fidelity assessment, and updating compared with test data, are presented for a reference flight condition. Results from piloted simulation trials, with a ‘new’ Flight Test Manoeuvre (FTM), are included to illustrate flight simulator fidelity assessment methods and to illustrate how the Rotorcraft Certification by Simulation process can be achieved