Unmanned aerial vehicles for contact-based inspection

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2023
Thesis identifier
  • T16639
Person Identifier (Local)
  • 201761369
Qualification Level
Qualification Name
Department, School or Faculty
  • Multirotor Unmanned Aerial Vehicles (UAVs) have become effective tools for in situ inspection of energy sector infrastructure where aging-related degradation causes critical failures but asset scale and inaccessibility make frequent manual assessment cost-prohibitive. Minimising human access to wind, nuclear and oil and gas facilities through rapid visual screening, UAVs have drastically reduced the associated risks of work at height, radiation exposure, and hazardous atmospheres. To further improve structural insight and cut downtime, this thesis examines airborne deployment of other established Non-Destructive Evaluation (NDE) methods via physical surface contact. An over-actuated multirotor deploying a dry-coupled ultrasonic wheel probe is developed as a novel thickness mapping strategy. Using bi-axial tilting propellers in a unique thrust-vectoring tricopter layout, this system may efficiently apply interaction forces from omnidirectional flight. Through laboratory testing, stable and repeatable inspection is then characterised in various representative operations. Against a reference sample mounted vertically or beneath a 45° overhang, static point-thickness measurements consistently show mean absolute error under 0.10 mm. This error also remains below 0.28 mm in dynamic rolling measurements suited to area thickness profiling, highlighting successful airborne delivery of multi-modal ultrasonic testing. A novel multirotor-crawler hybrid vehicle is also developed for contact-based assessment of pipes, tanks, and other cylindrical assets. Utilising a multidirectional propeller array under energy-optimised interaction control, this may bypass surface obstructions and adhere itself to the target in a unique fly-crawl-fly inspection mode. Laboratory testing demonstrates enhanced stability, showing mean absolute static pose deviation below 1.03 mm and well-regulated helical translation around the full pipe circumference. Deploying immediate-proximity visual inspection, line features and defects larger than 102 μm are then resolvable, with extensions to photogrammetric reconstruction and orthogonal imaging recording 3D geometry and full location context. Quantified operational performance bounds of each system thereby support industrial adoption and further development of airborne NDE.
Advisor / supervisor
  • Pierce, S. Gareth
  • Bolton, Gary
  • Dobie, Gordon
  • MacLeod, Charles
Resource Type