DJI Inspire 1 and STORM Racing Drone

Strategic sensor placement in unmanned systems is a critical part of the design process.  A well-designed unmanned system will utilize sensors in configurations that reduce interference/error, and provide overlap to improve accuracy/reliability.   For the purpose of this exercise, sensor placement in the DJI Inspire 1 and the STORM Racing Drone will be examined.

The DJI Inspire 1 is a high-end consumer UAS that is commonly used in the aerial photography and video industry.  The Inspire 1 is built around a carbon fiber body and features a high quality camera, smart device connectivity, dual operator controls, and automatic position holding.  The Inspire 1 weighs approximately 4.5 pounds, has a maximum altitude of 14,753 feet, and features a flight time of 18 minutes.

The CCD camera on the Inspire 1 is a 4K camera capable of shooting video at 30 frames per second.  According to DJI, “The lens consists of 9 separate elements, including an aspherical element, for extreme clarity, while Adobe DNG RAW support gives you the power to make every shot a masterpiece” (DJI, 2015).  The placement and control of the camera system is what sets the Inspire 1 apart from the competition.  The camera is attached to a 3-axis gimbal on the bottom of the frame and allows for 360 degrees of movement.  Using dual operator controls, the camera can be controlled by a secondary operator focused on photography allowing the primary operator to focus on flying.

The Inspire 1 utilizes an Inertial Measurement Unit (IMU) to report velocity and orientation.  The IMU contains accelerometers, a gyroscope, GPS, and a magnetometer to processes its position.  The magnetometer and GPS provide overlapping sensor data that allows the magnetometer to verify the GPSs directional accuracy.  The IMU is positioned to avoid the electric motors from interfering with the magnetometer. 

Additionally, the Inspire 1 features a proprietary Vision Positioning System (VPS).  The VPS combines a downward pointing CCD camera, a range finder, and a dedicated low power CPU to allow GPS-free position holds.  The VPS is located on the bottom rear of the airframe.  The VPS system was built to accommodate indoor photography in areas of poor GPS reception.

            The STORM Racing Drone Type A is a 250-class consumer First Person View (FPV) ready quad-copter.  The 250-class is defined as a quad-copter whose diagonally opposing propeller center points measure between 240 and 260 mm across the airframe.  The Type A aims to set itself apart from the competition by way of its responsive controls and low latency FPV. 

            The Type A mounts a camera to the very front of the airframe providing the FPV operator an optimum 110-degree view.  The FPV transmitter is a Team Blacksheep TBS UNIFY 5G8 200MW 32CH.  The transmitter is a 5.8 GHz, 200mW, 32 channel device that is positioned on the top center of the Type A.  The transmitter is the maximum distance from the electric motors and flight control receiver.

            The Type A does not feature many accessories as extra weight reduces speed.  The Type A features standard electronic speed controllers attached to all four motors and a CCD3 flight controller.  Helipal, manufacturer of the Type A, states that it “is a very stable small outdoor drone with powerful Real-time Video Feed system” (Helipal, 2015).

References

DJI (2015). Inspire 1. [ONLINE] Available at: http://www.dji.com/product/inspire-1. [Last Accessed 28 January, 2015].

Helipal (2015). STORM Racing Drone Type-A - User Manual. [ONLINE] Available at: http://image.helipal.com/helipal-storm-racing-drone-type-a-v1-1.pdf. [Last Accessed 28 January, 2015].

Maritime SAR: The Bluefin-21

The Bluefin-21 is an Autonomous Underwater Vehicle (AUV) that has been deployed to assist in several maritime Search and Rescue (SAR) operations.  On May 22nd, 2014, NBC News reported that a Bluefin-21 assisted in the search for the missing Malaysian Airlines Flight 370.  The Bluefin-21 is 16.2 feet long, has a diameter of 21 inches, and a dry weight of 1,650 pounds.  The AUV was built for a wide variety of applications ranging from offshore survey, search and salvage, archaeology, oceanography, to mine countermeasures.

The Bluefin-21 is built around the idea of payload flexibility and sensor integration.  According to the company, “Bluefin has integrated more than seventy different sensors from major suppliers throughout our AUV product line, building an extensive portfolio of payload flexibility” (Bluefin, 2015).  The standard Bluefin-21 sensors are divided into the categories of imaging, navigation, and scientific.

The Bluefin-21 has many Proprioceptive (PC) and Exteroceptive (EC) sensors designed for the maritime environment.  Imaging sensors include side scan sonar (EC), synthetic aperture sonar (EC), multi-beam echo-sounders (EC), imaging sonar (EC), sub-bottom profiler (EC), and a CCD camera (EC).  Navigation sensors include a USBL system (EC), an LBL system (EC), a Doppler velocity logger (PC), altimeter (PC), pressure sensor (PC), inertial navigation sensor (PC), inertial measurement unit (PC), acoustic tracking transponder (EC), and a compass GPS (EC).

The Bluefin-21 is an extremely capable remote sensing platform.  A major drawback with the Bluefin is a lack real-time data transmitting to the surface.  The Bluefin-21’s sensing data is recorded onboard and then downloaded after the craft surfaces.  In order to improve the SAR capabilities of the  Bluefin-21, better methods of transmitting data through water are needed.  Extremely Low Frequencies (ELFs) are known to be somewhat effective in water.  ELFs range from 3 to 30 hertz.  An ELF transmitter on the Bluefin-21 may be able to relay information to a buoy equipped with a receiver transmitter to rebroadcast the signal to a ship.        

A UAS can work in conjunction with a AUV during SAR operations to improve the search.  A UAS equipped with a bathymetric lidar system (mentioned last week) and a thermal camera can scan large areas quickly, and subsequently relay points of interest to the Bluefin-21 operators.  This type of collaboration can be valuable in time sensitive operations.    

The main advantage the Bluefin-21 has over a manned submarine is cost.  It is cheaper using an AUV over a manned submarine.  The unit price of a US Navy Los Angeles class submarine is $900 million.  The unit price of a manned NR-1 research submarine is approximately $67 million. The main advantage of using the Bluefin-21 over competing AUVs is depth; the Bluefin-21 has reached depths of over 4,695 meters.

Bathymeteric Lidar

For my first blog post, I am reviewing an article on a new Light Detection and Ranging (lidar) system.  Lidar has been used in all major unmanned systems, ranging from UGVs to satellites.  The article is titled, “Smaller Lidars Could Allow UAVs to Conduct Underwater Scans”, and was posted by Product Design and Development.   

The Georgia Technical Research Institute (GTRI) has designed a new bathymeteric lidar system that may allow unmanned aircraft to conduct improved underwater scans.  Bathymetric lidars transmit an infrared and green spectrum light wave.  The infrared band is quickly absorbed and detects the waters surface while the green band penetrates the water.  

The issue in current bathymetric systems is that the water causes refraction when computing the path of the light.  This makes bathymetric systems less accurate as water depth is increased.  To solve this problem, GTRI researchers have devised a new approach called total propagated uncertainty (TPU). 

The TPU implements rapid computing Field Programmable Gate Arrays (FPGAs) to propagate errors from the individual lidar measurements.  This provides better water penetration imagery.  Professor Grady Tuell, the projects principle research scientist stated,  “In our laboratory tests, we’re computing about 37 million points per second – which is exceptionally fast for a lidar system and gives us a great deal of information about the sea floor in a very short period of time”.  He further explains, “The key is we’re using FPGAs to do the necessary signal conditioning and signal processing, and we’re doing it at exactly the time that we convert from an analog signal to a digital signal.”  FPGAs are traditionally used for fixed-point digital signal processing.  TPU offers competing levels of floating-point processing thus improving imagery.

The lidar system weighs approximately 30 pounds, allowing it to be flown from small UASs.  The new bathymetric lidar will have many military applications, but it will also be a benefit to the civilian sector.  Mapping of the sea floor can assist in search and rescue operations, searching for oil, tracking whales, observing geological processes, and much more. 

Reference:

Product Design and Development (2014). Smaller Lidars Could Allow UAVs to Conduct Underwater Scans. [ONLINE] Available at: http://www.pddnet.com/news/2014/12/smaller-lidars-could-allow-uavs-conduct-underwater-scans. [Last Accessed 16 January 2014].