Winkvist S.,University of Warwick |
Rushforth E.,University of Warwick |
Young K.,Manufacturing Technology Center
Industrial Robot | Year: 2013
Purpose - The purpose of this paper is to present a novel approach to the design of an autonomous Unmanned Aerial Vehicle (UAV) to aid with the internal inspection and classification of tall or large structures. Focusing mainly on the challenge of robustly determining the position and velocity of the UAV, in three dimensional space, using on-board Simultaneous Localisation and Mapping (SLAM). Although capable of autonomous flight, the UAV is primarily intended for semi-autonomous operation, where the operator instructs the UAV where to go. However, if communications with the ground station are lost, it can backtrack along its path until communications are re-established. Design/methodology/ approach - A UAV has been designed and built using primarily commercial-off-the-shelf components. Software has been developed to allow the UAV to operate autonomously, using solely the on-board computer and sensors. It is currently undergoing extensive flight tests to determine the performance and limitations of the system as a whole. Findings - Initial test flights have proven the presented approach and resulting real-time SLAM algorithms to function robustly in a range of large internals. The paper also briefly discusses the approach used by similar projects and the challenges faced. Originality/value - The proposed novel algorithms allow for on-board, real-time, three-dimensional SLAM in unknown and unstructured environments on a computationally constrained UAV. © Emerald Group Publishing Limited.
Yaghi A.H.,Manufacturing Technology Center |
Hyde T.H.,University of Nottingham |
Becker A.A.,University of Nottingham |
Sun W.,University of Nottingham
Materials Research Innovations | Year: 2013
Finite element (FE) simulations of the welding of two high grade steel pipes are described. The first is a P91 steel pipe welded with a similar P91 weld consumable, and the second is a P92 steel pipe welded with dissimilar nickel-chromium based weld consumables. Both welds are multipass circumferential butt welds, having 73 weld beads in the P91 pipe and 36 beads in the P92 pipe. Since the pipes and welds are symmetric around their axes, the FE simulations are axisymmetric, allowing high FE mesh refinement and residual stress prediction accuracy. The FE simulations of the welding of the P91 and P92 pipes comprise thermal and sequentially coupled structural analyses. The thermal analyses model the heat evolution produced by the welding arc, determining the temperature history throughout the FE models. Structural analyses use the computed temperature history as input data to predict the residual stress fields throughout the models. Post-weld heat treatment (PWHT) of both pipes has also been numerically simulated by assuming that the FE models obey the Norton creep law during the hold time period at 760uC. The residual stresses presented here have all been validated by corresponding experimental measurements. Before PWHT, it has been found that, at certain locations in the weld region and heat affected zone (HAZ) in the pipes, tensile hoop and axial residual stresses approach the tensile strength of the material, presenting a high risk of failure. It has also been found that PWHT substantially reduces the magnitude of residual stresses by varying degrees depending on the material. © W. S. Maney & Son Ltd. 2013.
Tandy M.,University of Warwick |
Young K.W.,Manufacturing Technology Center
GPS Solutions | Year: 2013
In global navigation satellite system ambiguity resolution, it is common to use a configurable acceptance test, like the popular ratio test, to control the failure rate. Work in the literature proposes acceptance tests which let users directly choose an acceptable failure rate, but it focuses on instantaneous and fixed duration ambiguity resolution (where results may be success, failure, or undecided). We present a fixed failure rate acceptance test which avoids undecided results by varying the duration of the ambiguity resolution window. The proposed method uses Monte Carlo simulation with a time-correlated noise model to select acceptance test parameters that will minimize mean ambiguity resolution time while maintaining the target failure rate. Results of real-world experiments with single-frequency data from receivers with patch antennas show with 24 h of stationary data the method produces a mean ambiguity resolution time reduction of 52 % (from 525 to 250 s) compared with a ratio test. In a test with 90 min of kinematic data, the reduction was 33 % (from 620 to 410 s). © 2012 Springer-Verlag.
Alcock J.R.,Cranfield University |
Attia U.M.,Manufacturing Technology Center
Procedia CIRP | Year: 2013
This paper presents an assessment of the feasibility of a through-life approach for the development of high performance microsystems (HPMs) - microsystems, or microelectromechanical systems (MEMS) designed to operate in extreme conditions. It introduces HPMs, and their applications and presents reliability as the main through-life challenge to their market growth. It characterizes reliability challenges in HPMs and details the current understanding of failure modes in HPMs. It describes progress in failure prediction in HPMs and discusses future challenges. Finally, it summarizes why a general Design for Reliability approach would be advantageous for HPMs and summarizes progress in implementing such an approach. © 2013 The Authors. Published by Elsevier B.V.
Everton S.K.,University of Nottingham |
Everton S.K.,Manufacturing Technology Center |
Hirsch M.,University of Nottingham |
Stravroulakis P.,University of Nottingham |
And 2 more authors.
Materials and Design | Year: 2016
Lack of assurance of quality with additively manufactured (AM) parts is a key technological barrier that prevents manufacturers from adopting AM technologies, especially for high-value applications where component failure cannot be tolerated. Developments in process control have allowed significant enhancement of AM techniques and marked improvements in surface roughness and material properties, along with a reduction in inter-build variation and the occurrence of embedded material discontinuities. As a result, the exploitation of AM processes continues to accelerate. Unlike established subtractive processes, where in-process monitoring is now commonplace, factory-ready AM processes have not yet incorporated monitoring technologies that allow discontinuities to be detected in process. Researchers have investigated new forms of instrumentation and adaptive approaches which, when integrated, will allow further enhancement to the assurance that can be offered when producing AM components. The state-of-the-art with respect to inspection methodologies compatible with AM processes is explored here. Their suitability for the inspection and identification of typical material discontinuities and failure modes is discussed with the intention of identifying new avenues for research and proposing approaches to integration into future generations of AM systems. © 2016 The Authors.