Referenced Large-Scale Airborne Measurement System

• Applicants: Privatdozent Dr.-Ing. Markus Kästner; Professorin Dr.-Ing. Annika Raatz
• Subject Area: Measurement Systems ; Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541021498

The rise of unmanned aerial vehicles (UAVs) holds significant promise for advancing remote sensing and surface reconstruction capabilities. These UAVs offer an extensive workspace, but the measurement accuracy of UAV-based metrology lags behind traditional methods like stationary laser trackers, which are currently used for digitizing large industrial objects or infrastructure. To address this quality gap, our project aims to develop a UAV-based Structured Light Scanning (SLS) system with high precision and an expansive measurement range. This system will be capable of creating detailed scans of machinery, buildings, and infrastructure with sub-millimeter precision, critical for applications such as engineering, maintenance, preservation, and design. To achieve the desired accuracy, we employ a combination of novel hardware-based sensor stabilization and computational phase deviation compensation. The active sensor stabilization counteracts unintended drone movements during the capture of structured light patterns, enabling longer exposure times and significantly improving measurement quality. The hardware stabilization is performed by a hexapod robot mounted on the UAV, receiving real-time pose measurements from a high-precision Laser Tracing System (LTS) through multilateration. Multilateration involves using distance measurements from several laser tracers, referred to as satellites, which track the sensor's movement by following fixed reflectors on the sensor platform. These tracking satellites are mounted on multiple Autonomous Mobile Robots (AMRs) that can reposition the satellites to adjust the measurement area. This feature allows the system to expand its measuring area by moving the measurement volume, enabling the capture of large scale, high-quality 3D point clouds. In this configuration, the UAV follows a series of pre-recorded poses connected by a predefined flight path alongside the building. At each pose, the SLS system takes a measurement and transmits it to a ground station, where all measurements are combined to create a complete 3D model of the building. Developing this high precision measurement system necessitates the creation of a novel measurement concept, calibration and referencing techniques, as well as the development of hardware and algorithms for active sensor stabilization. This proposal outlines our approach to achieving these objectives, while also assessing the error budget and optimizing the system in terms of energy consumption.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2433: Metrology on flying platforms