Currently, under FAA rules, drones can only be operated during day-time hours, and within "civil twilight" hours, typcially 30 minutes before or after the sun sets.
For commercial companies operating drones, this can be especially restrictive. Drones are used for search and rescue operations, filming events, capturing news footage, or for security purposes. The good news is that it is possible to receive a "night waiver" (§ 107.29) from the FAA if you can prove that your drone, in addition to adhering to all the other normal regulations, has at least a three nautical mile radius of visibility.
There are many ways to approach how to overcome this requirement. Here are a few methods that are being used or are currently under development.
The most obvious solution for night visibility is to use a lighting system—sort of the same way headlights are used on cars. There are many different approaches to this method: many commercial solutions are already available to add spotlights onto your drone, and there are also ways to develop your own DIY solution as well.
Interestingly, there are companies who are pushing the boundary by adding 1000 Watt lighting systems to their drones. This apparently can achieve 0.25 million Lumens! Intense lightning like this could be useful for security, filming, and search and rescue.
Others, taking the direct and less complicated approach, are just attaching flashlights to their drones.
The most important part of this approach is that the three nautical mile radius limitation is still met in varied conditions in worst-case scenarios.
In 2015, drone company DJI and infrared imaging company FLIR partnered together to develop a thermal camera imaging solution for drone vision and navigation. Thermal cameras detect infrared waves being emitted by objects—warming objects will appear red while cold objects will appear black. So, even in the absence of visible light, objects can be detected. While these cameras are quite expensive for the hobbyist, they can be excellent solutions for commercial operators.
However, it’s also possible to build your own camera to take images in the infrared light spectrum using an inexpensive digital camera, an infrared spotlight, and some time. By taking the camera apart, removing the IR filter, adding a visible light filter, and installing it onto your drone with an IR spotlight (keeping in mind any payload weight limitations your drone might have), you can make an IR vision-capable drone. The best part is that the IR spotlight isn’t visible to human eyes.
A Novel Approach
Reseachers in Switzerland have published a paper on a navigation system that can operate in low-light conditions with high-dynamic range and without motion-blur problems. This is achieved by combining the best attributes of traditional cameras and dynamic vision sensors (DVS).
Cameras operate by sending frame-by-frame images, where a DVS only detects and transmits the changes that occur in a scene at the pixel-level. If using only a traditional camera, issues arise with blurring if a scene is moving too quickly. With a DVS, not enough information is provided if the scene isn’t moving at all. The team combined the traditional camera’s intensity frames with the DVS’s inertial frames, which resulted in a hybrid solution that can operate in daylight conditions or low-light conditions at fast speeds—or when not in motion at all.
Being able to operate drones 24-hours is a huge advantage and can open up even more novel uses for them. What other solutions
Feature image courtesy of Droneality.