UNSY 605, Assignment 7.5, Sense and Avoid Sensor Selection

     Unmanned aerial systems’ (UAS) sensor systems for sense-and avoid (SAA) functions present a formidable challenge.  The system must provide a level of safety at least equal to that provided by a human operator’s SAA capabilities.  This threshold must be met for the Federal Aviation Administration (FAA) to approve of UAS operations in the National Airspace (NAS) and, ultimately, for the public’s approval.  A Group 2 category UAS is relatively small and light, restricting a SAA system to compact, lightweight, and power-efficient components.
    The Advanced Scientific Concepts (ASC) Peregrine 3D Flash laser detection and ranging (LIDAR) system is a suitable sensor for SAA functions on a Group 2 category UAS.  The Peregrine weighs only one pound and measures only 2 inches by 3 inches by 6 inches.  The LIDAR requires 24 watts of starting power with 13 watts for continued operation and operates at 20 Hertz.  The Peregrine features a 60 degree field of view (FOV) lens and a Class I eye-safe laser.  Figure 1 presents a view of the exterior of the Peregrine.

Figure 1.  The Peregrine 3D Flash LIDAR.

The sensor also features widely compatible support equipment and operating software.  The Peregrine can withstand environmental conditions that make it suitable for an aerial platform.  The maximum detection range of the LIDAR varies depending on laser power and the reflectivity of the detected object (“ASC”, 2015).  Tests by LIDAR technology enthusiasts have produced detection ranges of approximately 1,200 feet (400 meters) (LIDAR News Staff, 2015).
    The Peregrine LIDAR uses a solid state three-dimensional staring array.  By comparison, a LIDAR using a scanning array usually contains an oscillating mirror to sweep the laser pulses through an arc and an inertial measurement unit to measure the aircraft’s orientation.  These components ensure the position of each pulse is recorded to ensure accuracy in the data collected (Anderson et al., 2006). 
Figure 2 provides an example of a scanning array (Glennie et al., 2013).

Figure 2.  A example of a mirror and prism in a LIDAR scanning array.

The Peregrine does not require these moving parts to achieve similar results.  These properties allow for a reduction in size and weight of the overall system.  The lack of requirement for an inertial system to record orientation also means the Peregrine would be more forgiving of a carrying UAS’ maneuvers or light turbulence.  ASC’s product page (2015) explains that their LIDAR illuminates an area incorporating the FOV with a single 5 nanosecond pulse per frame.  The reflected laser light is captured in the form of three-dimensional point clouds and co-registered intensity data.  Resolution of 128 x 32 pixels can be achieved with a 4:1 aspect ratio.  Standard Ethernet ports and power connectors ensure the Peregrine is easily integrated into UAS platforms.
    The Peregrine 3D Flash LIDAR presents a SAA capability for independent operation.  SAA systems such as Automated Dependent Surveillance-Broadcast (ADS-B) have been recommended for UAS operations in the NAS (Marshall, 2013, p. 1-2).  However ADS-B relies on cooperation among aircraft and ground stations.  An aircraft without ADS-B installed will not be detected by the system.  ADS-B would also not be of any help during an encounter with a flock of large birds such as Canada geese.  A LIDAR such as the Peregrine would provide a very useful, independent SAA system to supplement ADS-B coverage.

References

Advanced Scientific Concepts (ASC).  Peregrine 3D Flash LIDAR Vision System [Product Sheet].  Retrieved from http://www.advancedscientificconcepts.com/products/Peregrine.html

Anderson, H., McGaughey, R., Reutebuch, S., Schreuder, G., & Agee, J.  (2006, July 31).  Website of Report to U.S. Forest Service, Joint Fire Science Program: The Use of High-Resolution Remotely Sensed Data in Estimating Crown Fire Behavior Variables – LIDAR Overview.  Retrieved from http://forsys.cfr.washington.edu/JFSP06/index.htm


Glennie, C., Carter, W., Shrestha, R., & Dietrich, W.  (2013, July 5).  Geodetic Imaging With Airborne LiDAR: The Earth's Surface Revealed.  Reports on Progress in Physics, 76(8).


LIDAR News Staff.  (2015, January 26).  Lower Cost Flash LIDAR.  LIDAR News.  Retrieved from http://blog.lidarnews.com/lower-cost-flash-lidar/

Marshall, P.  (2013, July 12).  The Tech That Will Make Drones Safe for Civilian Skies.  GCN.  Retrieved from https://gcn.com/articles/2013/07/12/drone-uav-sense-and-avoid-technologies-civilian-airspace.aspx