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