Sense and Avoid Sensor Selection
The purpose of this activity is to select and discuss a sensor that is currently being developed, or is already commercially available, that would be a good option for a small unmanned aerial system (sUAS) sense and avoid solution. The technology should be able to fit on an be employed by an sUAS weighing less than 55 pounds. This discussion will include both operational details and technical specifications of the technology, and why it is ideal for an sUAS. I have selected the Aerotenna uSharp Patch Collision Avoidance Radar.
Aerotenna’s uSharp Patch is advertised as “The world’s most compact and cost-effective radar solution for collision avoidance” (μSharp Patch Collision Avoidance Radar, 2017). It became commercially available in November 2016, and is currently being sold for $499 through the company’s website. Weighing less than 150 g, and having a power consumption of less than 1.5 W and 5 V, it is ideally suited to fit onto virtually all sUAS (μSharp Patch Collision Avoidance Radar, 2017).
This system possesses several advantages over existing visual sensing systems such as stereo vision and Light Detection and Ranging (LiDAR) due in large part to its use of radio waves. One of the major disadvantages of LiDAR is the fact that its power output is limited in order to remain safe to human eyes. As an example, a Class 1 laser typically emits approximately 40 microwatts of power, and a Class 2 approximately 1 mW (Laser Standards and Classifications, 2016). One of the more popular LiDAR systems currently available, the Velodyne HDL-32E, uses a Class 1 laser, giving it a maximum range of 100 m (HDL-32E, 2017). The higher available power output of the Aerotenna radar gives it a range of up to 200 m, allowing for increased reaction time and space for the sUAS. The use of microwaves for its radar also gives it improved all weather capability over visual systems, in that it can easily see day or night through rain, snow, and clouds. Additionally, it is not susceptible to blind spots caused by the sUAS’s airframe itself, as the microwaves pass through it (Aerotenna Releases 360° Sense-and-Avoid Radar, Advances Drones Closer to Autonomous Flight, 2016). Its final major benefit is that it possesses an adaptive sensing range, meaning that as the sUAS’s speed increases, the power output and range of the radar increases, allowing the sUAS to detect obstacles at a greater distance. As the sUAS decelerates, the power output decreases, conserving battery power (μSharp Patch Collision Avoidance Radar, 2017).
The uSharp Patch does have some drawbacks compared to LiDAR, most notably in its resolution. The HDL-32E provides a resolution of up to 2 cm (HDL-32E, 2017), while the uSharp’s resolution is 5 cm (μSharp Patch Collision Avoidance Radar, 2017). This level of resolution, however, is more than adequate for the purpose of sense and avoid. The light weight of the system, combined with its low power requirements and ability to operate effectively day or night make it an optimal solution for airborne sense and avoid for sUAS.
References:
Aerotenna Releases 360° Sense-and-Avoid Radar, Advances Drones Closer to
Autonomous Flight. (2016, October 03). Retrieved May 06, 2017, from
http://aerotenna.com/aerotenna-releases-360-sense-avoid-radar-advances-drones-
closer-autonomous-flight/
HDL-32E. (2017). Retrieved May 06, 2017, from http://velodynelidar.com/hdl-32e.html
Laser Standards and Classifications. (2016). Retrieved May 06, 2017, from
https://www.rli.com/resources/articles/classification.aspx
Radar altimeter and collision avoidance sensors for UAVs. (2017). Retrieved May 06, 2017,
from http://aerotenna.com/sensors/#usharp
μSharp Patch Collision Avoidance Radar. (2017). Retrieved May 06, 2017, from http://aero
tenna.com/shop/%CE%BCsharp-patch/