Unmanned System Data Protocol and Format - DJI Phantom 4

4.5 - Research Assignment: Unmanned System Data Protocol and Format

There are many commercial unmanned aerial systems (UAS) on the market that currently incorporate a multitude of sensors that require data systems, protocols, and storage methods to make them an effective and functional system.  One system currently on the market that incorporates this technology is the DJI Phantom 4 (P4).  The P4 officially went on sale March 15, 2016 (Martin, 2016).  The P4 has an impressive sensor suite that allows for it to handle a multitude of functions.  According to Jim Martin (2016), the P4 has the following capabilities based on the sensors on board:

•          An Obstacle Sensing System that uses ultrasonic sensors plus two front facing and two downward facing cameras allowing it to see and avoid people, buildings, or other obstacles.
•          An Active Track function that lets the system track a moving subject without GPS navigation.
•          A TapFly function that allows the user to fly the system with a smartphone by tapping where the user wants it to go, in a well-lighted environment, allowing the avoidance technology to handle the flight path.
•          A vision positioning system with an effective range of up to 10 meters.
•          A 4K camera that is attached to a gimbal that can record slow motion video capture of 120 frames per second at 1080 pixels.
•          An intelligent flight battery with a capacity of 5350mAh, and a flight time of 28 minutes.

The P4 allows the data collected by the sensors to be stored in several ways.  One way data can be collected and stored is by an onboard micro SD card, with a max capacity of 64 gigabytes (DJI, 2016b).  DJI has developed the DJI GO app for Apple iOS and Android devices that uses a real-time HD downlink to see what the camera sees (DJI, 2016a).  According to DJI (2016a), the following data from sensors can be downloaded the DJI GO app:

•          The aircraft’s position and heading.
•          Images and videos.
•          Fight log data through the Flight Record feature.

The DJI GO app has the following specifications:

•          Equivalent isotropically radiated power (EIRP) of 100mW
•          Power Spectral Density of 6.9mW/MHz and a live view working frequency of 2.4GHz ISM
•          A live view quality of 720p at 30 frames per second with a latency of 220ms, depending on the conditions and mobile device.
•         Required operating systems of iOS 8.0 or later and Android 4.1.2 or later (DJI, 2016b).

As mentioned previously the P4 is equipped with an obstacle sensing system, vision positioning system, and a 4K camera.  The Obstacle Sensing System has a sensory range of 2 to 49 feet and must have a surface with a clear pattern and adequate lighting of greater than 15 lux, for its operating environment (DJI, 2016b).  The vision positioning system has an altitude and operating range of 0 to 33 feet, along with the same lighting requirements as the Obstacle Sensing System (DJI, 2016b).  According to DJI (2016b), the 4K camera specifications are:

•          12 megapixels, attached to a gimbal with a 3-axis stabilization and pitch of -90^o to +30^o.
•          A lens with an operating field of view (FOV) of 94^o 20mm.
•          An ISO range of 100 to 3200 for video and 100 to 1600 for photos.
•          A shutter speed of 8s to 1/8000s with a maximum image size of 4000x3000 pixels.
•         A max video bitrate of 60 Mbps
•         JPEG and DNG photo files and MP4 and MOV (MPEG-4 AVC/H.264) movie files.
•          An operating temperature range of 32 to 104 degrees Fahrenheit.

In order to power the P4 it is incorporated with an intelligent flight battery system.  The intelligent flight battery weighs 462 grams; is a LiPo 4S battery with 15.2 volts; has energy of 81.3Wh; and has a maximum charging power of 100W with an operating temperature of 14 to 104 degrees Fahrenheit (DJI, 2016b).  

The P4 also has several other sensors that are built into the airframe to assist in flight operations.  In order to assist the global positioning system (GPS) the P4 has dual inertial measurement units (IMUs) and dual compass modules.  The data these sensors receive is run through algorithms to check for accuracy, any inaccurate data is then discarded without affecting the flight of the system (DJI, 2016c). 

The P4 is controlled by the DJI Phantom 4 remote control.  It has an operating frequency of 2.400 GHz to 2.483 GHz with an operating voltage of 7.4 volts at 1.2 amps; a maximum transmission distance of 3.1 miles; can operate in temperatures from 32^o to 104^o Fahrenheit with a 6000mAh LiPo 2S battery; and has a FCC transmitter EIRP of 23 dBm (DJI, 2016b).  Last, according to DJI (2016b), the P4 has the following specifications:

·         Weighs 1380 grams with a maximum speed of 20 meters per second.

•          An ascent speed of 6 meters per second with a descent speed of 4 meters per second.
•          Can operate at a maximum of 19,685 feet or 6,000 meters above sea level.

•          Has a vertical and horizontal hover accuracy of +/- .1 meters and +/- .3 meters respectively when vision positioning is active.

            The DJI Phantom 4 is an excellent commercial UAS for an end user who wants to use it for aerial videography and photography.  There are a couple of changes I would make to the system.  First, it appears that the camera cannot be switched out with the gimbal it is attached to.  I would make it so it can be used with several different brands of cameras, such as GoPro and Sony, and other thermal infrared, multispectral, and hyperspectral sensors.  I think it would be good for DJI to also find another means of data storage for the Phantom 4.  I think this would be an important feature to consider incase the micro SD card becomes damaged during flight, and if the DJI GO app becomes inoperable during an operation.  DJI might consider adding cloud storage solutions for data after flight operations, too.  DJI could try to incorporate other solid state drives (SSD) into the system for storage solutions, such as the Microsemi Corporation’s low power mSATA SSD that has 64GB single-level cell (SLC) flash capacity in a 50mm x 30mm compact size, designed for unmanned aerial vehicles (Unmanned Systems Technology, 2015).

References:

DJI. (2016a). DJI GO - Capture and Share Beautiful Content Using this New App. Retrieved June 26, 2016, from DJI: http://www.dji.com/product/goapp

DJI. (2016b). DJI Phantom 4 - Spec, FAQ, Tutorials and Downloads. Retrieved June 26, 2016, from DJI: http://www.dji.com/product/phantom-4/info#specs

DJI. (2016c). Phantom 4 - DJI's smartest flying camera ever. Retrieved June 26, 2016, from DJI: http://www.dji.com/product/phantom-4

Martin, J. (2016, April 20). DJI Phantom 4 release date, price, specs: the drone that can fly itself and avoid obstacles. Retrieved June 26, 2016, from PC Advisor: http://www.pcadvisor.co.uk/new-product/gadget/dji-phantom-4-release-date-price-specs-3636067/

Unmanned Systems Technology. (2015, August 13). Microsemi Introduces Secure Solid State Drive for High-Security Embedded Applications. Retrieved June 26, 2016, from Unmanned Systems Technology: http://www.unmannedsystemstechnology.com/2015/08/microsemi-introduces-secure-solid-state-drive-for-high-security-embedded-applications/

UAS Sensors related to an aerial photgraphy UAS and an FPV Racer

3.4 Research Assignment: UAS Sensor Placement

Recently aerial photography, from high definition videos to still photos, has become a big point of focus in the commercial UAS industry.  There are numerous UAS on the market that seem to be capable of these tasks, as this industry continues to grow.  One UAS that is very capable of performing these tasks and has a lot of options for the end users is the 3DR Solo.  3DR has designed and developed an UAS that has many functions and will be able to adapt to the evolving enhancements to the product.  According to 3DR (2016) the Solo has the following functions:

• ·       An orbit function that allows for GoPro camera to lock on to any object with the push of a button, allowing it to fly around in a circle keeping the camera focused on the subject.

• ·       A follow mode that allows the user to go completely hands free and focus on the user at all times, and it has the ability to enter “free look” mode to let the user take control of the camera.

• ·       A cable cam mode that acts as a virtual cable to keep it on a track to set unlimited key frames at any points in the air, which allows the user to pan and tilt the camera without piloting.

• ·       A selfie mode that allows recording clips directly to a user’s smartphone for saving and sharing.

• ·       A pano mode that allows for capturing an aerial panorama, allowing the Solo to automatically pan and snap photos.

In addition to the above functions 3DR has designed the Solo to adapt to future enhancements to the UAS.  Future enhancements include an accessory bay with a ballistic parachute system for safety in the event of system failure, wireless updates, swappable motor pods, LED lights and an optical flow sensor, which most of these attach to the bottom of the frame of 3DR Solo (3DR, 2016a).  Along with this the 3DR Solo can record live HD video and 12 megapixel photos from a GoPro camera attached to a gimbal on bottom of the frame, satellite view for location accuracy, one touch shot control, real-time safety information, and user-defined geofencing through the 3DR Solo iOS and Android App (3DR, 2016c).

Due the safety functions incorporated into the 3DR Solo, multiple video and photo recording modes, and evolving adaptability the 3DR Solo offers for the end user, I have chosen it as a UAS platform to record HD video and still photos below 400 feet.

In addition to aerial photography applications increasing lately in the UAS industry, FPV racing has grown exponentially worldwide.  Due to this there have been many commercial FPV racing UAS that have entered the market recently.  In not being very familiar with racing drones I researched top racing drones on the market.  In conducting my research one FPV racing UAS that I came across is the Vortex 250 Pro by Immersion RC.  It has been recommended through a drone buying guide as the top expert FPV racing drone (Nixon, 2016).  The Vortex 250 Pro seems to be a top of the line 250 size FPV racer due to sensors and other items that it comes with, and therefore I would chose this as an FPV racing UAS.  According to Immersion RC (2016) it includes the following items:

• ·       An approximate weight of 415 grams with no battery or HD camera

• ·       A power requirement of 3s-4s LiPo battery

• ·       State of the art F3 flight controller processor

• ·       2^nd Generation 20 Amp Ez electronic speed control, with custom 2204-2300kV motors

• ·       Built in 2 megabyte black box recorder

• ·       Carbon fiber frame

• ·       An Integrated 40 channel NexWaveRF 5.8GHz video transmitter

• ·       Tiltable, vibration-free camera mount

• ·       Includes a GoPro ¾ camera mount

There is one downfall to this FPV racer in that a few extra items need to be purchased initially.  A compatible receiver and display device must be purchased separately for operating and setting up the vehicle (Immersion RC, 2016). 

The above mentioned 3DR Solo and the Vortex 250 Pro are two UAS that are very capable of carrying out the intended tasks for the end user.  The 3DR Solo camera placement on the bottom of the frame allows for it to capture HD video and still images an end user would need.  In addition to this the accessory bay allows for flexibility and adaption to the systems for future applications.  The front positions of the cameras and the tiltable mounts on the Vortex 250 allow for it to be a very high performance racer, along with the placement of the flight control board within the carbon fiber frame (Immersion RC, 2016).  I would recommend these two UAS to an end user to accomplish their goals. 

References:

3DR. (2016a). Built to Evolve 3DR Drone & UAV Technology. Retrieved June 19, 2016, from 3DR: https://3dr.com/evolve/

3DR. (2016b). Smart Shots 3DR Drone & UAV Technology. Retrieved June 19, 2016, from 3DR: https://3dr.com/smart-shots/

3DR. (2016c). Solo Smart Drone 3DR Drone & UAV Technology. Retrieved June 19, 2016, from 3DR: https://3dr.com/solo-drone/

Immersion RC. (2016). Vortex 250 Pro. Retrieved June 20, 2016, from Immersion RC: http://www.immersionrc.com/fpv-products/vortex-250-pro/

Nixon, A. (2016, May 1). Racing Drone Buyers Guide. Retrieved June 20, 2016, from Best Drone for The Job: http://bestdroneforthejob.com/drones-for-fun/racing-drone-buyers-guide-2/

2.5 Blog Activity: Unmanned Systems Maritime Search and Rescue

Unmanned Systems Maritime Search and Rescue

In the past several years there have been a multitude of autonomous underwater vehicles (AUVs) that have been used for search and rescue operations.  These operations have ranged from searching for sunken ships to searching for aircraft that have gone missing in the ocean.  In conducting research on search and rescue AUVs, the Sentry AUV has shown to be very successful, and has the capable sensors, to handle these types of missions.  Several instances within the past few years where this has happened is the Sentry finding an ancient shipwreck off the coast of North Carolina in 2015, and being used to find the voyage data recorder of El Faro cargo ship in February of 2016 (Eggleston, Van Dover, & Delgado, 2015; MarEx, 2016).  The Sentry has a multitude of equipment and sensors it can be fitted with that allows it to be successful on missions in the maritime environment.  The specifications of the Sentry and sensors that allow it to operate in harsh maritime environments according to Woods Hole Oceanographic Institution (WHOI) (2015) include:

•          An operating depth of up to 6,000 meter (19,685 feet).
•          Dimensions of 9.7 feet in length by 7.2 feet in width, and a height of 5.8 feet weighing 2,750 pounds without extra equipment.
•          It has an operating range of 38 to 54 miles at a max speed of 2 knots.
•          For propulsion it uses 4 brushless DC electric thrusters on pivoting wings with lithium ion batteries with a bus power of 48 to 52 Volts.
•          It has an endurance time of 26 to 60 depending on its depth and mission type along with a descent and ascent speed of 50 meters per min for both descent and ascent.
•          The Navigation system is USBL Navigation with real-time acoustic communications, Doppler velocity log (DVL), and an inertial navigation system (INS).
•          It can be equipped with a vast array of sensors based on the mission.

The sensor suite includes several proprioceptive and exteroceptive sensors that are specifically designed for the maritime environment.  According to Woods Hole Oceanographic Institution (2015) Sentry specification sheet these sensors include the following:

•          Nortek Acoustic Doppler Velocimeter
•          IXSEA PHINS 1 inertial navigation systems (INS)
•          Blueview P900-90 forward looking imaging multibeam sonar
•          Reson SVP70 sound velocity probe
•          SBE FastCAT 49 conductivity, temperature, and depth sensor (CTD)
•          Edgetech 2200-M 120/410kHz side scan sonar, Edgetech 2200-M 4-24kHz sub bottom profiler, and an Edgetech 2205 - 850kHz DF sidescan sonar

In addition to this it can be fitted with other sensors that are not just specific to the maritime environment.  These sensors include a magnetometer, an 11 megapixel camera, and an inclinometer (Woods Hole Oceanographic Institution, 2015).

In order for the Sentry to be more successful in search and rescue operations several modifications could be made to the system.  In my opinion it has a long turnaround time to switch out the payload, sensors, or other equipment once it is on deck, as the turnaround time is 16 hours (Woods Hole Oceanographic Institution, 2015).  WHOI defines the turnaround time as, “vehicle on deck to vehicle launch.  Turn around time can include redeployment of the same vehicle” (Woods Hole Oceanographic Institution, 2015).  To me this seems like a long time if the payload would need to be switched out with different sensors quickly for a certain mission, especially if time is critical. 

In the beginning of search and rescue operations the Sentry could work in conjunction with an unmanned aerial system (UAS), and sensors deployed on them to help locate wreckage or debris of a downed aircraft.  This could be done to help identify areas more quickly where wreckage or survivors may be located, or areas for search and rescue teams to avoid.  UAS could be deployed with thermal imaging cameras to help search for people or debris that may be on the surface of the water.  Other camera and 3D imagery sensors on UAS could be used to take pictures and map the surrounding area.  One way this could be done with the Sentry is through an UAS that is being developed by researchers at John Hopkins University.  Recently researchers at John Hopkins University Applied Physics Laboratory (APL) have developed a corrosive resistant UAS, called the Corrosion Resistant Aerial Covert Unmanned Nautical System or CRACUNS, that can be launched from a UUV at a depth of several hundred feet under water, which can then provide surveillance from the air in the area the UUV is located (JHU Applied Physics Laboratory, 2016).  If systems like this continue to be developed, that can work in cooperation with unmanned maritime systems (UMS), to make search and rescue operations more efficient, then the opportunities are limitless. 

There are multiple advantages of using UMS over manned systems.  One major advantage I see is that UMS allow for operations to take place at greater depths with sensors that manned systems may not be able to operate at.  This in turn puts fewer lives at risk for underwater search and rescue operations that may happen in harsh underwater environments.  Sonars on unmanned systems allow for maps and imagery of the seafloor to be created at greater depths than manned vehicles.  In some situations, unmanned vehicles may allow for longer missions, too, since crews of manned vehicles may have to sleep or rest in the time frame that an unmanned vehicle can conduct a mission without having to surface.

References:

Eggleston, D., Van Dover, C., & Delgado, J. (2015, July 17). Centuries-Old Shipwreck Discovered Off North Carolina Coast. Retrieved June 11, 2016, from North Carolina State University: https://news.ncsu.edu/2015/07/shipwreck-2015/

JHU Applied Physics Laboratory. (2016, March 17). New UAV Can Launch from Underwater for Aerial Missions. Retrieved from https://www.youtube.com/watch?v=o17x3XTA-DM

MarEx. (2016, February 11). Search for El Faro VDR On Again. Retrieved June 11, 2016, from The Maritime Executive: http://www.maritime-executive.com/article/search-for-el-faro-vdr-on-again

Woods Hole Oceanographic Institution. (2015). Sentry [PDF File]. Retrieved June 11, 2016, from Woods Hole Oceanographic Institution: file:///C:/Users/sjean/Downloads/16G0099-Sentry_One-Pager_Edits1-screen_172424.pdf

Woods Hole Oceanographic Institution. (2015). Sentry Specifications & Sensors. Retrieved June 11, 2016, from Woods Hole Oceanographic Institution: https://www.whoi.edu/main/sentry/specifications-sensors

Woods Hole Oceanographic Institution. (2015). Standard Turnaround Time Between Vehicle Lowerings. Retrieved June 11, 2016, from Woods Hole Oceanographic Institution: https://www.whoi.edu/page.do?pid=11256