7.4 Sense and Avoid Sensor Selection

            There are numerous small unmanned aerial systems (sUAS) available on the market for commercial applications to the average consumer.  Due to this there has been an increase in focus on developing a good sense and avoid sensor suite for sUAS applications.  Many are currently trying to develop better sense and avoidance technologies for sUAS.  The increase in commercial sUAS available to consumers has a created a need for an emphasis on safety to protect the public, national airspace, and infrastructure from sUAS accidents.  One company that has developed a system to help with this is DJI.  The system has several key features that make it an advanced sense and avoid system.  DJI has created the Guidance visual sensing system that has five sensor modules and one central processor, that integrates visual cameras, ultrasonic sensors and advanced computer vision algorithms (DJI, 2016c).  These sensors allow for it to perform several key functions for obstacle sensing and avoidance, along with precision accuracy when hovering.  The system continously scans the environment and detects obstacles in real time, and when used with a DJI flight controller it can tell the system to avoid collisions at high speeds (DJI, 2016c).  Along with this it also allows for the system to have precision positioning capabilities without the GPS.  When flying at high speeds high, stereo algorithms allow for positioning information over most terrains, and the system is effective at altitudes of up to 65 feet, which allows for hovering that is accurate to within centimeters (DJI, 2016c).  Figure 1 shows the hardware and sensors that come in the Guidance package.

Figure 1: (Source: DJI, 2016a)                

The Guidance system can be used on several DJI sUAS.  According to DJI (2016a), Guidance has the following specifications:   

• Core dimensions of 78.5 mm x 53.5 mm x 14 mm, with a weight of 64 grams.
• Sensor dimensions of 170 mm x 20 mm x 16.2 mm, with a weight of 43 grams per sensor.
• A 200 mm VBUS Cable, with a weight of 11.6 grams.  
• An effective sensor range of .20 m to approximately 20 meters, and must have good lighting with texture-rich surface and clear patterns.
• A velocity detection range of 0 to approximately 16 m/s, 2 m from the ground.
• A velocity detection accuracy of .04 m/s, 2 m from the ground.
• A positioning accuracy of .05 m, 2 m from the ground.
• A power consumption of 12 W with all five sensors, and an input voltage of 11.1 volts to approximately 25 volts.
•  An operating temperature range of -10^o Celsius to approximately 40^o Celsius.
• Is supplied with five VBUS cables and has UART level of 3.3. 

Of the items mentioned above, the following items are included in the Guidance box; one Guidance core, five Guidance sensors, five standard VBUS cables, one long spare VBUS cable, one CAN-Bus cable, one micro-USB cable, one micro-USB cable extender, one UART cable, and a package of 25 M2x5 screws (DJI, 2016b).  The technology incorporated into the DJI Guidance systems makes it a very capable sUAS sense and avoidance system. 

            If I were to have any recommendations it would be to improve it to be effective above 65 meters and to be able to be used with all sUAS flight controllers for systems under 55 pounds.  As previously mentioned the Guidance system can be used with several DJI sUAS.  The following video demonstrates the use of the Guidance system on a DJI Matrice (Drone Scan, 2015). Video link: https://www.youtube.com/watch?v=V94zsX3wh_I

The cost of the Guidance system is $999.00, with free shipping, through the DJI website (DJI, 2016b).

References:

DJI. (2016a). Buy Guidance DJI Store. Retrieved July 17, 2016, from DJI: http://store.dji.com/product/guidance?clickaid=DM97QXQIf8W2Xt3aEXs7niufIREJobPH&clickpid=418902&clicksid=0c04d98cae5b356f7ba3544b21a03074%23/overview#/spec

DJI. (2016b). Buy Guidance DJI Store. Retrieved July 18, 2016, from DJI: http://store.dji.com/product/guidance?clickaid=DM97QXQIf8W2Xt3aEXs7niufIREJobPH&clickpid=418902&clicksid=0c04d98cae5b356f7ba3544b21a03074#/overview

DJI. (2016c). Guidance: A revolutionary visual sensing system for aerial platforms. Retrieved July 18, 2016, from DJI: http://www.dji.com/product/guidance

Drone Scan. (2015, August 21). dji guidance optic flow testing in warehouse. Drone Scan. Retrieved from https://www.youtube.com/watch?v=V94zsX3wh_I

Control Station Analysis for an Unmanned Ground Vehicle

Activity 6-4 Research Assignment: Control Station Analysis

Technology is continuing to evolve and advance for unmanned systems.  Unmanned systems continue to increase the amount of data they can provide from their sensors.  Due to the advancement in technology for these systems it is important for the operator to invest in a reliable and universal control station.  It is advantageous for the end user to have a control station that can operate unmanned systems from several platforms, such as both unmanned aerial systems (UAS) and unmanned ground vehicles (UGV).  In researching products for UGV control stations that have this capability UAV Factory’s commercial-off the shelf (COTS) dual display mobile station (DDMS) fits this description.  It can control a multitude of unmanned vehicles, including UAS, UGV, remotely operated vehicles (ROV), and bomb disposal robots  (UAV Factory, 2016).  It is important to the end user that this system is capable of operating both aerial and ground vehicles, for cost savings, so an end user does not have to purchase a separate system later if they were to need one for operating a UAS.

UAV Factory’s COTS DDMS is a rugged system that has a multitude of features for UGV operations.  According to UAV Factory (2016), the hardware specifications include the following:

•        Its dimensions are 1000 x 420 x 170 mm, with a weight of 18.9 kg.
•          An operating temperature of -20^o to 60^o Celsius.
•          Electronics compartment dimensions of 320 x 270 x 80 mm.
•          A M4 threaded mounting grid, with a 45 mm pitch and an aluminum mounting kit for the electronics mounting base.
•          An included accessory bag with the dimensions of 220 x 160 x 70 mm.
•          A rugged plastic case with side and carry handles, wheels, pressure purge valve, and an optional shoulder strap.
•          A computer docking station for mounting a computer.
•          A 17 inch TFT 1280x1024 (SXGA) display that has a brightness of 1600 nits and an       optional VGA input, with an optional touch screen.

The control station has an impressive power distribution system, too.  It includes two 108 Wh hot-swappable lithium-ion batteries with a two hour battery life; can be powered by 10 to 32 volts of direct current with over-voltage and reverse polarity protection; two 50 Ohm antennas; and provides two 12 volts of direct current, 50 W power outputs for the electronics compartment and external devices (UAV Factory, 2016).  Last according to UAV Factory (2016), there are the following ports for connection to the computer:

•          2 serial RS-232
•          5 USB
•          2 Ethernet
•          1 Composite Video in
•          1 optional VGA
•          1 microphone in
•          1 audio out
•          PCMCIA slot
•          1 HDMI

As seen by the power distribution listed above and the connections available to the computer, the control station has a very sophisticated and advanced power distribution system. 

The ground control station has a lot of features available for UGV control operations and not many changes are needed to the system.  One disadvantage to the system is an end user must purchase a Panasonic Toughbook CF-31 to operate the control station, and it is currently the only computer that is compatible with the control station (UAV Factory, 2016).  According to UAV Factory (2016), the COTS DDMS must be used with a Panasonic Toughbook CF-31 that has the following specifications:

•          A 13.1 inch XGA touch screen LED 1024x768 display.
•          Durability of MIL-STD-810G & IP65 certified (6' drop).
•          A brightness of 1100 nits.

One recommendation I would have is for control station to be compatible with other computers besides the Panasonic Toughbook CF-31, or for it to come with its own compatible computer with data analyzing and tracking software.  It appears to the end user that they must purchase and download their own software, to the Panasonic Toughbook, for tracking flight operations and collecting data.  This could allow for even more cost savings for the end user, which in turn may also increase sales of the control station if it is compatible with more computers that end users may already be using.

References:

UAV Factory. (2016). Portable Ground Control Station. Retrieved July 10, 2016, from UAV Factory: http://www.uavfactory.com/product/16