This blog post will discuss the data format,
protocols, and storage methods associated with the AR.Drone 2.0. The AR.Drone 2.0 is a hobby UAS built by the
Paris based Parrot Company. Parrot is a
public company whose revenues reached $272,691,500
USD in 2011. ARS Technica has reported that over half a million AR.Drone units
have been sold as of March 2013 (ARS
Technica, 2013). I specifically
chose the AR.Drone 2.0 for this activity because it was my introduction to the
hobby UAS world when I purchased one in 2012.
The AR.Drone 2.0 uses two cameras to
stream real-time video to smart devices.
The first camera is a forward-looking, wide angle, high definition 720p
camera with a frame rate of 30fps. The
second camera is a downward pointing Quarter Video Graphics Array (QVGA) with a
resolution of 320 x 240 pixels. The QVGA
camera has a frame rate of 60 fps and is used for groundspeed measurement. Both cameras stream to a H.264 encoding base
profile, and is transmitted to a smart device over a Wi-Fi b/g/n
connection.
H.264 is also known as MPEG-4 Part
10-Advanced Video Coding (MPEG-4 AVC).
This is currently one of the most popular video compression formats. However, the High Efficiency Video Codec
(HEVC) H.265 may soon be replacing H.264.
Benchmark tests comparing H.264 and H.265 show that H.265 is capable
of “improving upon current streaming by
cutting the required bitrate by up to 50 percent” (Tested, 2014). I would recommend that Parrot consider
upgrading their encoding base profile to H.265.
The AR.Drone 2.0 “can be controlled
from any client device supporting the Wi-Fi ad-hoc mode”, (AR.Drone Developer
Guide SDK 1.6). The AR.Drone creates a
Wi-Fi network allowing supported smart devices running flight control software
to connect. Wi-Fi 802.11b/g/n server has
bandwidths of 22/20/40Mhz respectively, with outdoor ranges of 460/460/820
feet. The 802.11n connection is ideal
due to both its bandwidth and range. The
only Wi-Fi connection with a longer range is the 802.11a at up to 16,000 feet;
however, its low data stream rate makes it impractical for streaming high
definition video.
Firmware data on the AR.Drone is the
only data normally stored onboard. The
firmware can be updated through a USB 2.0 port on the bottom of the
AR.Drone. The AR.Drone 2.0 currently
supports the connection of a USB 2.0 flash drive to store recorded video on the
UAS. AR.Drone users are encouraged to
record video streamed to their smart devices via Android and iOS flight control
applications. I would recommend that
Parrot consider using a small SD storage slot to record video onboard the AR.Drone. The SD slot will not add significant weight,
and it frees the USB for the possibility of adding aftermarket hardware.
The AR.Drone 2.0 uses 6 miniaturized
inertial measurement units to provide pitch, roll, and yaw measurements. The sensors provide data to the processor for
stabilization and tilt control. Additionally,
an ultrasound telemeter is used to determine altitude. The firmware in the AR.Drone controls exactly
how all of the sensory input is used.
References:
Cornish, David (2013). ESA Launches Drone App to Crowdsource
Flight Data. [ONLINE] Available at:
http://arstechnica.com/gadgets/2013/03/esa-launches-drone-app-to-crowdsource-flight-data/.
[Last Accessed 07 February, 2015].
Fenlon, Wesley (2013). What You Should Know about The H.265 Video
Codec. [ONLINE] Available at: http://www.tested.com/tech/web/453188-what-you-should-know-about-h265-video/.
[Last Accessed 07 February, 2015].
Intel (2013). Real-Time CPU Based H.265/HEVC Encoding Solution with Intel Platform
Technology. [ONLINE] Available at:
https://software.intel.com/sites/default/files/white_paper_real-time_HEVC_encodingSolution_IA_v1.0.pdf.
[Last Accessed 07 February, 2015].
Parrot (2011). AR.Drone Developer Guide SDK 1.6. [ONLINE] Available at:
https://abstract.cs.washington.edu/~shwetak/classes/ee472/notes/ARDrone_SDK_1_6_Developer_Guide.pdf.
[Last Accessed 07 February, 2015].
Parrot (2015). AR.Drone 2.0 Technical Specifications. [ONLINE]
Available at: http://ardrone2.parrot.com/. [Last Accessed 07 February, 2015].
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