Thursday, 15 June 2017

Fly the drone above water - Floating base design for UAVs

Fly the drone above water - Floating base design for UAVs

Date: May 30, 2017
Location: Dublin

Using drones for photography and inspection have become more and more popular. In some situation,  such as recording the water sports or doing under bridge inspection, we have to fly the drone close to the water surface. It looks like an easy job,  but it is really a challenging for drone operators. The done should always keep a safe distance to the water surface, but the cross wind and waves will prevent the operator to do so. Even advanced drones are equipped with high-tech sensors, such as ultrasonic sensor, visual detector, barometer for altitude holding, they are not working well in an environment filled with random reflection and inconstant air flows.

Figure 1. Flying above the water

Figure 2. Floating base for UAVs

In our research, for under bridge inspection, we designed a cheap floating base to avoid water damage, shown in Figure 1 and Figure 2. The float base only includes a frame and four bottles and appropriate for different drones. In the field survey, it works well. If you are interested in it and want to make one for your ‘baby’, here are some tips:

1. Frame

The frame is used for connecting the drone and fixing bottles caps. You can use any light and solid materials (acrylic or aluminum) or any manufacturing method (machining or 3D printing), but remember to leave am empty areas below the camera and other sensors. In addition, make the angle between two front bottles bigger can further ensure the camera is unblocked. 

Figure 3. Frame design

2. Bottles

Theoretically, a 1L bottle can support 1kg's weight. Thus for a DJI Phantom 4 (about 2kg), 4x500ml bottles will be enough. But considering the momentum when the drone falls off and the possible deformation of plastic bottles, we used 4 1L bottles in our case.

Instead of installing the bottles vertical or horizontal,  we using a 30-degree angle to avoid the flip-over problem (vertical setting will have). It solved the inefficient aerodynamic problem and lower floating center problem (horizontal setting will have) as well.  If you are lucky to find some narrow neck bottles, the aerodynamic performance could be further improved.

Images of the test and field survey

Flight time and wind resistance test (20 min)

Weight and balance test (2.5 kg)

Under bridge survey

Siyuan Chen 
School of Civil, Structural and Environmental Engineering
University College Dublin, Ireland