Charalampos Loukas

Dr. Charalampos Loukas

orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 July 2021 in Sensors
Verified
Journal Article
Open access
PDF file
MVMomchil Vasilev
Momchil Vasilev
CMCharles MacLeod
Charles MacLeod
CLCharalampos Loukas
Charalampos Loukas
Yashar JavadiYashar Javadi
Yashar Javadi
RVRandika K. W. Vithanage
Randika K. W. Vithanage
AGAnthony Gachagan
Anthony Gachagan
The growth of the automated welding sector and emerging technological requirements of Industry 4.0 have driven demand and research into intelligent sensor-enabled robotic systems. The higher production rates of automated welding have increased the need for fast, robotically deployed Non-Destructive Evaluation (NDE), replacing current time-consuming manually deployed inspection. This paper presents the development and deployment of a novel multi-robot system for automated welding and in-process NDE. Full external positional control is achieved in real time allowing for on-the-fly motion correction, based on multi-sensory input. The inspection capabilities of the system are demonstrated at three different stages of the manufacturing process: after all welding passes are complete; between individual welding passes; and during live-arc welding deposition. The specific advantages and challenges of each approach are outlined, and the defect detection capability is demonstrated through inspection of artificially induced defects. The developed system offers an early defect detection opportunity compared to current inspection methods, drastically reducing the delay between defect formation and discovery. This approach would enable in-process weld repair, leading to higher production efficiency, reduced rework rates and lower production costs.

17 May 2018 in IEEE Geoscience and Remote Sensing Letters
Verified
Journal Article
Closed access
ASAman Shrestha
Aman Shrestha
CLCharalampos Loukas
Charalampos Loukas
Julien Le KernecJulien Le Kernec
Julien Le Kernec
FFFrancesco Fioranelli
Francesco Fioranelli
VBValentina Busin
Valentina Busin
LVLance Voute
Lance Voute
Lameness is a significant problem for performance horses and farmed animals, with severe impact on animal welfare and treatment costs. Lameness is commonly diagnosed through subjective scoring methods performed by trained veterinary clinicians, but automatic methods using suitable sensors would improve efficiency and reliability. In this letter, we propose the use of radar micro-Doppler signatures for contactless and automatic identification of lameness, and present preliminary results for dairy cows, sheep, and horses. These proof-of-concept results are promising, with classification accuracy above 85% for dairy cows, around 92% for horses, and close to 99% for sheep.

31 May 2022 in Sensors
Verified
Journal Article
Open access
PDF file
RZRastislav Zimermann
Rastislav Zimermann
EMEhsan Mohseni
Ehsan Mohseni
MVMomchil Vasilev
Momchil Vasilev
CLCharalampos Loukas
Charalampos Loukas
RVRandika K. W. Vithanage
Randika K. W. Vithanage
JDJialuo Ding
Jialuo Ding
The demand for cost-efficient manufacturing of complex metal components has driven research for metal Additive Manufacturing (AM) such as Wire + Arc Additive Manufacturing (WAAM). WAAM enables automated, time- and material-efficient manufacturing of metal parts. To strengthen these benefits, the demand for robotically deployed in-process Non-Destructive Evaluation (NDE) has risen, aiming to replace current manually deployed inspection techniques after completion of the part. This work presents a synchronized multi-robot WAAM and NDE cell aiming to achieve (1) defect detection in-process, (2) enable possible in-process repair and (3) prevent costly scrappage or rework of completed defective builds. The deployment of the NDE during a deposition process is achieved through real-time position control of robots based on sensor input. A novel high-temperature capable, dry-coupled phased array ultrasound transducer (PAUT) roller-probe device is used for the NDE inspection. The dry-coupled sensor is tailored for coupling with an as-built high-temperature WAAM surface at an applied force and speed. The demonstration of the novel ultrasound in-process defect detection approach, presented in this paper, was performed on a titanium WAAM straight sample containing an intentionally embedded tungsten tube reflectors with an internal diameter of 1.0 mm. The ultrasound data were acquired after a pre-specified layer, in-process, employing the Full Matrix Capture (FMC) technique for subsequent post-processing using the adaptive Total Focusing Method (TFM) imaging algorithm assisted by a surface reconstruction algorithm based on the Synthetic Aperture Focusing Technique (SAFT). The presented results show a sufficient signal-to-noise ratio. Therefore, a potential for early defect detection is achieved, directly strengthening the benefits of the AM process by enabling a possible in-process repair.

12 August 2022 in Sensors
Verified
Journal Article
Open access
PDF file
EFEuan Alexander Foster
Euan Alexander Foster
GBGary Bolton
Gary Bolton
RBRobert Bernard
Robert Bernard
MMMartin McInnes
Martin McInnes
SMShaun McKnight
Shaun McKnight
CMCharles MacLeod
Charles MacLeod
Inspection of components with surface discontinuities is an area that volumetric Non-Destructive Testing (NDT) methods, such as ultrasonic and radiographic, struggle in detection and characterisation. This coupled with the industrial desire to detect surface-breaking defects of components at the point of manufacture and/or maintenance, to increase design lifetime and further embed sustainability in their business models, is driving the increased adoption of Eddy Current Testing (ECT). Moreover, as businesses move toward Industry 4.0, demand for robotic delivery of NDT has grown. In this work, the authors present the novel implementation and use of a flexible robotic cell to deliver an eddy current array to inspect stress corrosion cracking on a nuclear canister made from 1.4404 stainless steel. Three 180-degree scans at different heights on one side of the canister were performed, and the acquired impedance data were vertically stitched together to show the full extent of the cracking. Axial and transversal datasets, corresponding to the transmit/receive coil configurations of the array elements, were simultaneously acquired at transmission frequencies 250, 300, 400, and 450 kHz and allowed for the generation of several impedance C-scan images. The variation in the lift-off of the eddy current array was innovatively minimised through the use of a force–torque sensor, a padded flexible ECT array and a PI control system. Through the use of bespoke software, the impedance data were logged in real-time (≤7 ms), displayed to the user, saved to a binary file, and flexibly post-processed via phase-rotation and mixing of the impedance data of different frequency and coil configuration channels. Phase rotation alone demonstrated an average increase in Signal to Noise Ratio (SNR) of 4.53 decibels across all datasets acquired, while a selective sum and average mixing technique was shown to increase the SNR by an average of 1.19 decibels. The results show how robotic delivery of eddy current arrays, and innovative post-processing, can allow for repeatable and flexible surface inspection, suitable for the challenges faced in many quality-focused industries.

1 July 2021 in Journal of Manufacturing Processes
Verified
Journal Article
Closed access
CLCharalampos Loukas
Charalampos Loukas
VWVeronica Williams
Veronica Williams
RJRichard Jones
Richard Jones
MVMomchil Vasilev
Momchil Vasilev
CMCharles N. MacLeod
Charles N. MacLeod
AGAnthony Gachagan
Anthony Gachagan

19 August 2022 in NDT & E International
Verified
Journal Article
Closed access
EDEuan Duernberger
Euan Duernberger
CMCharles MacLeod
Charles MacLeod
DLDave Lines
Dave Lines
CLCharalampos Loukas
Charalampos Loukas
MVMomchil Vasilev
Momchil Vasilev