Browsing by Author "Williamson, Alex"

Now showing 1 - 7 of 7
  • Thumbnail Image
    ItemOpen Access
    Autonomous Architecture for UAV-based Agricultural Survey
    (AIAA, 2020-01-05) Mondal, Sabyasachi; Williamson, Alex; Xu, Zhengjia; Tsourdos, Antonios
    This paper presents the concept of autonomous architecture for UAVs to minimize human involvement for agricultural surveying. Agricultural surveying applications include monitoring crop health and collecting ground truth data for treatment and harvest planning. The proposed architecture can automate the entire surveying process and helps farmers to obtain specific and essential knowledge about the crop more quickly. This architecture helps to increase crop yields while reducing operating costs. The autonomy is achieved by integrating functional modules such as Mission Planning, image processing, task allocation, and communication. This work is focused on describing the mission planning and task allocation since image processing is not within the scope.
  • Thumbnail Image
    ItemOpen Access
    Autonomous collection of ground truth data by unmanned aerial vehicles instructed using SMS text messages
    (IEEE, 2020-02-17) Williamson, Alex; Mondal, Sabyasachi; Xu, Zhengjia; Tsourdos, Antonios
    This paper describes a solution to increase the efficiency of collecting agricultural ground truth data by the use of one or more off-the-shelf drones to autonomously collect high quality RGB image data at low level, through the incorporation of a bespoke smartphone application that receives routing path-planned location data in the form of Short Message Service (SMS) text messages.
  • Thumbnail Image
    ItemOpen Access
    Cognitive communication scheme for unmanned aerial vehicle operation
    (IEEE, 2020-02-17) Xu, Zhengjia; Petrunin, Ivan; Tsourdos, Antonios; Sabyasachi, Mondal; Williamson, Alex
    An intelligent and agile wireless communication scheme is a key factor in provision of efficient air-to-ground (A2G) communication for unmanned aerial vehicles (UAVs) operations. For this purpose we review and propose an architecture for aeronautical cognitive communication system (ACCS) that will be providing command, control and communication (C3) link between ground control stations (GCSs) and multiple UAVs utilizing cognitive radio (CR) concept. The factors reviewed and accounted for in the design process are the topology of cognitive detectors, connectivity between cognitive detector and control agency, connection with unmanned traffic management (UTM) system, data link requirements imposed by cognitive scheme, failure notification and recovery, etc. The proposed ACCS is suitable for supporting UAV operations and features a distributed non-communication architecture consisting of GCS network in the ground zone, hybrid data link with the static uplink and the flexible downlink, demonstrating a dynamic nature overall with the frequency handoff scheme generated periodically in accordance with current spectrum environment.
  • No Thumbnail Available
    ItemOpen Access
    Data supporting: 'Development of a thermal excitation source used in an active thermographic UAV platform'
    (Cranfield University, 2022-08-31 16:49) Deane, Shakeb; Tsourdos, Antonios; Avdelidis, Nico; Zolotas, Argyrios; P. V. Maldague, Xavier; Ibarra-Castanedo, Clemente; Genest, Marc; Pant, Shashank; Williamson, Alex; Withers, Stephen; Ahmadi, Mohammadali
    This work aims to address the effectivenessand challenges of using active infrared thermography (IRT) on-board an unmannedaerial vehicle (UAV) platform. The work seeks to assess the performance ofsmall low powered forms of excitation which are suitable for activethermography and the ability to locate subsurface defects on composites. Anexcitation source in the form of multiple 250 W lamps are mounted onto a UAVand are solely battery powered with a remote trigger to power cycle them.Multiple experiments address the interference from the UAV whilst performing anactive IRT inspection. The optimal distances and time required for a UAV inspection using IRT is calculated. Multiple signal processing techniques areused to analyse the composites which helps locate the sub-surface defects. It was observedthat a UAV can successfully carry the required sensors and equipment for anActive thermographic NDT inspection which can provide access to difficult areas. Most active thermographic inspection equipment is large, heavy, and expensive. Furthermore, using such equipment for inspection of complexstructures is time-consuming. For example, a cherry picker would be required toinspect the tail of an aircraft. This solution looks to assist engineersinspecting complex composite structures and could potentially significantly reduce the time and cost of a routine inspection.
  • Thumbnail Image
    ItemOpen Access
    Developing drone experimentation facility: progress, challenges and cUAS consideration
    (IEEE, 2021-07-02) Panagiotakopoulos, Dimitrios; Williamson, Alex; Petrunin, Ivan; Harman, Stephen; Quilter, Tim; Williams-Wynn, Ian; Goudie, Gavin; Watson, Neil; Vernall, Phil; Reid, Jonathan; Puscius, Eimantas; Cole, Adrian; Tsourdos, Antonios
    The operation of Unmanned Aerial Systems (UAS) is widely recognised to be limited globally by challenges associated with gaining regulatory approval for flight Beyond Visual Line of Sight (BVLOS) from the UAS Remote Pilot. This challenge extends from unmanned aircraft flights having to follow the same ‘see and avoid’ regulatory principles with respect to collision avoidance as for manned aircraft. Due to the technical challenges of UAS and Remote Pilots being adequately informed of potential traffic threats, this requirement effectively prohibits BVLOS UAS flight in uncontrolled airspace, unless a specific UAS operational airspace is segregated from manned aviation traffic, often achieved by use of a Temporary Danger Area (TDA) or other spatial arrangements. The UK Civilian Aviation Authority (CAA) has defined a Detect and Avoid (DAA) framework for operators of UAS to follow in order to demonstrate effective collision avoidance capability, and hence the ability to satisfy the ‘see and avoid’ requirement. The National BVLOS Experimentation Corridor (NBEC) is an initiative to create a drone experimentation facility that incorporates a range of surveillance and navigation information sources, including radars, data fusion, and operational procedures in order to demonstrate a capable DAA System. The NBEC is part located within an active Airodrome Traffic Zone (ATZ) at Cranfield Airport, which further creates the opportunity to develop and test systems and procedures together with an operational Air Traffic Control (ATC) unit. This allows for manned and unmanned traffic to be integrated from both systems and procedural perspectives inside segregated airspace in a first stage, and then subsequently transiting to/from non-segregated airspace. The NBEC provides the environment in which a number of challenges can be addressed. This paper discusses the lack of target performance parameters, the methodology for gaining regulatory approval for non-segregated BVLOS flights and for defining peformance parameters for counter UAS (cUAS).
  • Thumbnail Image
    ItemOpen Access
    Integration of unmanned aerial vehicles and LTE: a scenario-dependent analysis
    (IEEE, 2022-03-30) Ozpolat, Mumin; Al-Rubaye, Saba; Williamson, Alex; Tsourdos, Antonios
    Commercial applications of Unmanned Aerial Vehicles (UAVs) are expected to be one of the disruptive technologies that can shape many activities spans from goods delivery to surveillance. To maximize the effectiveness of such UAV applications, it is very important to enable beyond-line-of-sight (BLoS) communications. Hence, integrated UAV with LTE network can be used to extend UAV operations beyond visual line-of-sight (BVLOS) communications. This paper investigates the ability of Long-Term Evolution (LTE) network to provide coverage for UAV in such rural and urban area, in particular for the uplink video transmission. The system design takes into consideration the dependency of the large-scale path loss, shadowing and line-of-sight probability on the height of the UAV in the simulation environment, which is obtained from industrial measurements, and a real-world communication infrastructure layout and configuration. Results show that UAV height is a very critical factor in terms of delay and jitter performance for urban micro scenarios, and less effective in urban macro scenarios. Nevertheless, average throughput performance is less sensitive to the change in parameters and communication environments when the application type is set as a 1080p-quality video feed. Besides, mobility performance is explored for different system parameters such as hysteresis margin, time-to-trigger under various communications scenarios. Finally, the finding presented in this paper can be a roadmap to facilitate UAV-LTE integration in the near future.
  • Thumbnail Image
    ItemOpen Access
    Pulsed and Vibro Thermographic results
    (Cranfield University, 2020-01-20 08:58) Deane, Shakeb; Ibarra-Castanedo, Clemente; Avdelidis, Nico; Tsourdos, Antonios; Zhang, Hai; P. V. Maldague, Xavier; Williamson, Alex; MacKley, Timothy; Yazdani Nezhad, Hamed; Davis, Maxwell
    The CFRP specimens were manufactured and purposely damaged via impact, in the Cranfield composite centre. Sample A4 was manufactured via manual woven, and the other twosamples were unidirectional. The composites consist of laying up pre-pregpiles to form a laminate stack, the material is then autoclave processed at 180oCand 7 bars for a few hours suitable for the thermoset resin cure, this isaccording to the supplier’s specification (Hexcel). There were three specimens,one that was undamaged, and two that had been impacted with a force of 15 and20 J of energy. The infrared camera used in this experiment was a FLIR Phoenix,with inSb sensor material, 3-5 mm, 640x512 pixels and allows data acquisitionat 50Hz. Thesurface of the specimens were positioned parallel to the camera lens. The data was acquired for 40 seconds with a 1.5millisecond integration time, that includes 10 frames before the flashes, plus1990 frames during cooling a total of 2000 frames where recorded. The softwareused to acquire the data was RDac from FLIR. For signal processing MATLAB andIr_view from Visiooimage inc were employed. Two advanced processing techniqueswere used; PCT (principal component thermography) and PPT (pulsed phasethermography).