Large-Scale Particle Image Velocimetry From an Unmanned Aerial Vehicle

Large-scale particle image velocimetry (LSPIV) enables non-intrusive and continuous characterization of surface flow velocities in natural watersheds. However, current LSPIV implementations are based on fixed cameras that only allow for surface flow monitoring at a limited number of locations on the water stream. This paper seeks to leverage the growing field of unmanned aerial vehicles to transform LSPIV practice, by enabling rapid characterization of large water flow systems in areas that may be difficult to access by human operators. Toward this aim, a lightweight and low cost quadrotor is developed to host a digital acquisition system for LSPIV. A gimbal is realized in house to maintain the camera lens orthogonal with respect to the water surface, thus preventing image orthorectification. Field experiments demonstrate that the vehicle is able to stably hover above an area of 1 x 1 m(2) for 4 min with a payload of 532 g. The feasibility of quadrotor-based LSPIV is demonstrated through tests in an outdoor laboratory setting and over a natural stream.