In this post we will explore a pair of UAVs in regards to suitability in their respective tasks and optimal placement. The first scenario requires high quality video and still images from an altitude of 400' AGL while the second scenario involves a racing UAV that must navigate a race course at high speeds.
The UAV chosen to represent the first scenario is the DJI S900
(DJI, 2016). This rather formidable platform is designed with professional
photography in mind. According to DJI (DJI, 2016), the S900’s specifications
are impressive. Built with a sturdy yet lightweight carbon-fiber frame (basic
weight 3.3 Kg) the S900 is capable of supporting added equipment nearly twice
the empty weight (maximum take-off weight 8.2 Kg). Powered by six brushless
motors with a maximum rating of 500 watts and electronic speed controllers with
a working current of 40 amps allows this aircraft to hoist payloads weighing up
to 4.9 Kg. A 6S 12000 mAh LiPo battery permits a hover time of approximately 18
minutes with a power consumption rate of 1000 – 3000 watts depending on how the
aircraft is flown.
A pair of design features incorporated into the S900 greatly
aid the professional photographer. The first is retractable landing gear which allows
a camera such as the Sony RX100 (Sony, 2016) or the Nikon D810 (Nikon, 2016), mounted
underneath the airframe, to have an unimpeded 360 degree view horizontally and
90 degrees down. The second design feature of this UAV is that the folding arms
incorporate and 8 degree inversion and a 3 degree inclination which enhances
platform stability in the pitch and roll axis (DJI, 2016).
Mounting the camera below the airframe and centered directly
beneath is a typical feature in multirotor UAVs which primarily record video or
still pictures from altitude to allow the maximum degree of field-of-view. Centering
the mass of the camera underneath improves stability and balance. Other UAVs
dedicated to aerial photography such as the widely popular DJI Phantom 3 (DJI,
2016) and the 3DR Solo (3DR, 2016) UAVs feature this camera placement in their
design along with the larger S900.
The second scenario involves a more aggressive class of UAVs
engaged in the sport of ‘Drone Racing’. Unlike their photography cousins which
rely on stability, wide field-of-view, and high-grade cameras to accomplish
their goal, the racing UAV relies on speed, acceleration, and agility to meet
the demands of competition (Nixon, 2016). These UAVs are flown by an operator
equipped with FPV (First Person View) goggles that receive video from a fixed
camera located at the nose of the racing platform. FPV racers typically fly a
few feet above the ground through a series of obstacles at maximum speed.
Forward mounting the camera permits the operator an unimpeded view directly
along the path of flight, a critical aspect when dodging obstacles at high
speeds.
The racing platform chosen to represent this class is the Inkonova
Tilt racer produced in Stockholm, Sweden. According to Inkonova’s website (Inkonova,
n.d.), the 3300mm (measured from motor
to motor) features computer controlled arms that angle the 1100 w flight
motors forward when accelerating which
allows the 800 gram Tilt UAV to accelerate from 0 to its top speed of
approximately 110 km/h in just 3.7 seconds.
Camera selection for racing UAVs is left up to the operator
based on personal preference. A guide posted by Drone Tech (Drone Tech, 2015)
recommends a CMOS 600TVL camera for a pair of important reasons. The 600TVL
camera is widely used in CCTV security cameras which makes it easily available
and more affordable than CCD equivalents, an important consideration given that
a forward mounted camera may suffer considerable damage when impacting an
object at high speed. The other important advantage that a 600TVL camera offers
over a higher definition camera is lower latency (Liang,
2016). At the velocities that racing UAVs travel, the operator simply cannot
afford to wait for FPV video to process while attempting to maneuver around a
race course.
Just as Mother Nature determined the placement of eyes on an
animal for survival purposes, proper placement of sensors on an unmanned
platform must also account for the environment in which it is meant to perform
for the best possible results. Whether sedately filming a scenic area or flying
at breakneck speed through an obstacle course, having the sensor in the best
possible position can make the difference between the success and failure of
the operator’s intent.
References:
References:
DJI.
(2016). Phantom 3 Professional.
Retrieved from http://www.dji.com/product/phantom-3-pro
DJI.
(2016). Spreading Wings S900 FAQs.
Retrieved from http://www.dji.com/product/spreading-wings-s900/info#specs
DJI.
(2016). Spreading Wings S900 Specs.
Retrieved from http://www.dji.com/product/spreading-wings-s900/info#specs
DJI.
(2016). Spreading Wings S900.
Retrieved from http://www.dji.com/product/spreading-wings-s900
Drone
Tech. (2015). FPV Cameras for your Drone.
Retrieved from
http://www.dronetrest.com/t/fpv-cameras-for-your-drone-what-you-need-to-know/1441/1
Inkonova.
(n.d.). Tilt Racing Drone. Retrieved
from http://www.tiltdrone.com/
Liang, O. (2016). Why use
a Dedicated Board Camera for FPV? Retrieved from
http://blog.oscarliang.net/gopro-mobius-fpv-camera-external-power/
Nikon. (2016). D810. Retrieved from
http://www.nikonusa.com/en/nikon-products/product/dslr-cameras/d810.html
Nixon,
A. (2016). Racing Drone Buyers Guide.
Retrieved from
http://bestdroneforthejob.com/drones-for-fun/racing-drone-buyers-guide-2/
Sony. (2016). RX100 Advanced
Camera with 1.0 inch Sensor. Retrieved from http://www.sony.com/electronics/cyber-shot-compact-cameras/dsc-rx100
Mark,
ReplyDeleteIn mounting a camera to the DJI S900, is it a gamble system, or does it not support image stabilization through the platform? That was one of the reasons I choose the DJI Inspire, it has a built in camera that accepts aftermarket lenses from a few popular manufactures. Nice informative blog post, Inkonova is new to me.
Don,
ReplyDeleteThanks for your comment. The S900 is meant to carry the Zenmuse Z15 series gimbals. The Z15 series has an IMU built in to the gimbal to provide image stabilization. The Inspire Pro uses the Zenmuse X5 gimbal which communicates with the aircraft's IMU for stabilization.
http://store.dji.com/accessories-others/aerial-gimbals
I too selected the Inspire for photography. The ability of the Inspire to transition the landing gear upward to alleviate any camera obstructions is phenomenal.
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