Sense and Avoid for Small Unmanned Aerial Systems

Aerotenna’s uSharp Sense-and-Avoid Radar is a commercially available sense and avoid solution for small Unmanned Aerial Systems (sUAS).  The uSharp radar utilizes microwave radar in the K-band (24 GHz) frequency range to detect objects in the horizontal plane within a full 360 degrees (Aerotenna Technology, n.d.).  The use of microwave radar as opposed to commonly utilized sensors such as electrooptical (EO) and infrared (IR) cameras or Light Detection and Ranging (LiDAR), enables a sUAS equipped with uSharp to sense and avoid other objects in all weather (heavy rain, fog, snow, clouds) and visibility conditions (night or low light levels) (Aerotenna Technology, n.d.).  The radar consists of eight antennas arranged in an octagonal formation and has a highly accurate range resolution of five centimeters and a response rate of 90 Hertz (Aerotenna, 2016).  It also has a range of 0.5 to 120 meters and can detect both moving and stationary objects (uSharp, 2017).  The ability to detect both moving and stationary objects is accomplished through the use of Frequency Modulation Continuous Wave (FMCW) technology.   This utilizes the frequency difference between transmission and reception signals to calculate range and the Doppler frequency shift of the return echo to calculate target velocity (Aerotenna Technology, n.d.).  Object location (azimuth angle) is determined by comparing “the phase difference between two or more [of the eight] receiving antennas” (Aerotenna Technology, n.d.).  The use of microwave radar also allows for the detection of water, vegetation, and power lines, which can be difficult to detect utilizing other sensor technologies (Aerotenna Technology, n.d.). 

Aerotenna. (2018). uSharp [digital image]. Retrieved from https://aerotenna.com/aerotenna-releases-360-sense-avoid-radar-advances-drones-closer-autonomous-flight/.

In addition to allowing for all weather flight, the use of a single radar sensor eliminates the need for multiple sensor systems, such as EO, LiDAR, and/or acoustic range sensors for sense and avoid in similar conditions.  This single sensor approach reduces weight and power consumption requirements associated with the use of multiple sensor systems on UAS.  In addition to its advanced detection capabilities, uSharp is ideal for sense and avoid on sUAS due to it’s small size and low power requirements.  The radar is “smaller than a baseball,” measuring 115 mm x 115 mm wide and 67 mm tall, and weighs 243 grams, or slightly over half a pound (uSharp, 2017).  This makes it ideal for installation on consumer sized quadcopter sUAS, such as the DJI Phantom series, or larger multirotor UAS.  Fixed wing UAS could also benefit from the use of uSharp as they would be able to detect and avoid objects approaching from behind (overtaking) or from the side of the sUAS.  Available flight time is maximized as uSharp consumes only 2.5 watts (5 volts DC) (uSharp, 2017).  The radar supports UART and CAN plug and play interfaces and can be utilized with “multiple open source flight controllers” (uSharp, 2017). 

The radar retails at $2499 (Microwave, 2018).  While this price may seem excessive, multirotor systems capable of integrating with the uSharp typically start around that price, not including onboard sensors for the task at hand (EO/IR cameras, LiDAR, etc).  Given the cost of these systems, the price of the uSharp isn’t excessive when one considers the safety factor, or investment protection against vehicle loss due to a collision, uSharp presents as well as the ability for the operator to more closely inspect obstacles than they would comfortably be able to without the system installed.

References: 

Aerotenna Releases 360 degree Sense-and-Avoid Radar, Advances Drones Closer to Autonomous Flight. (2016, October 3). Retrieved from https://aerotenna.com/aerotenna-releases-360-sense-avoid-radar-advances-drones-closer-autonomous-flight/.

Aerotenna Technology White Paper. (n.d.). Retrieved from https://aerotenna.com/datasheets/ Aerotenna_whitepaper.pdf.

Microwave Sensors. (2018). Retrieved from https://aerotenna.com/sensors/#usensing.

uSharp – 360 degree Sense-and-Avoid Radar. (2017, October 23). Retrieved from https://aerotenna.com/ datasheets/AerotennauSharp360Datasheet.pdf.