Unmanned aerial vehicle payload development for aerial survey
Sargeant, Nick (2012) Unmanned aerial vehicle payload development for aerial survey. Other thesis, Murdoch University.
Aerial imaging is key part of remote sensing and surveying, however traditionalacquisition methods such as satellite imagery and manned aircraft suffer from some limitations, namely, “high capital, operational and personnel costs, slow and weather-dependent data collection, restricted manoeuvrability, limited availability, limited flying time, low ground resolution”.Unmanned Aerial Vehicle have gained increasing attention in recent years as technological advancements such as sensor minimization have made them a viable alternative for aerial photogrammetry applications.
This report outlines the design and development of an Unmanned Aerial Vehicle suited for aerial survey. The first stage of the project involved a comprehensive literature review of existing research and evaluation of existing commercial solutions.
Existing commercial solutions such as the Gatewing X100 have proved capable in industry, however a number of limitations were identified; the most prominent being that the optical payload they carry is rigidly coupled to the airframe. As weather conditions become more adverse and wind gusts buffet aircraft, the camera’s axisis no longer orthogonal relative to groundwhich ultimately reduces the quality of the data captured.
Research identified from the literature review showed that “payload stabilization increases useful data capture during banking and increases processing success rate thanks to overall more predictable photo properties.”  In addition, “even when ordered to ‘fly straight’ over ground, deviations in roll and pitch of a few degrees occur due to turbulence and require extra image overlap pre-planned. Such overlap is costly in terms of flight time and performance worsens significantly during windy weather” . As such, the primary focus of this project was to design an improved imaging payload design that actively stabilized the camera.
The project started by evaluating a sub $200, open source, autopilot called the Ardupilot in a fixed wing aircraft. An appropriate camera and airframe were selected and a stabilized gimbal designed. During the project, setbacks were encountered whenCyber Technology, a company that provides ‘UAV solutions for search and rescue operations, military support, high-end surveillance, law enforcement, environmental conservation, agricultural operations, oil & gas structural inspection operations, and cinematography/photography applications’ showed interest and suggested that the project should instead focus on designing a surveying payload for one of their flagship products, the CyberQuad MAXI. An imaging payload was designed that satisfied all design constraints and was successfully integrated onto the CyberQuad. A flight planning parameter calculator was created and trial flights were then conducted.
The planned test methodology to evaluate the gimbal was to collect imagery of a test site, flying repeated missions with a given overlap first with gimbal stabilization enabled and then again with the stabilization disabled such that the gimbal remained fixed.
By contracting licensed surveyors to conduct a conventional surveyof the test site, using their data as an absolute reference, it was planned that the imagery captured could be processed using photogrammetric software and any improvements due to stabilization be quantified.
Unfortunately the data from the ground control survey was not provided in time to be used forprocessing; however the gimbal did improve image acquisition. Further, in partnership with the aforementioned surveying company, a commercial test flight wasconducted at Kwinana Bulk Terminal surveying an iron-ore stockpile with industry grade models generated as a result.
Development of the project will continue beyond the submission of this thesis and it is hoped that the survey data can be obtained and used for processing. This should definitively prove one of the original hypotheses of the research; using a stabilized gimbal allows for more efficient flight plans as a lower level of overlap is required. Additionally, the data generated from processing should allow an estimated function of overlap vs. model accuracy to be determined allowing future flight plans to be optimized.
|Publication Type:||Thesis (Other)|
|Murdoch Affiliation:||School of Engineering and Energy|
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