Actual and Potential Use of Drones in Precision Agriculture

Ed.: This is a guest blog by Alex Danovich of San Francisco Circuits.

Unmanned Aerial Vehicles (UAV), Unmanned Aerial Systems (UAS), Remotely Piloted Aircraft (RPA) or more commonly referred by mass media as drones are gaining popularity and often discussed for many new approaches to old applications. In the last couple years drones are rapidly gaining attention not only due to the traditional military applications but also civilian uses. This transition brings the drone industry closer into new commercial applications that literally pop up every day.

There are many directions of potential use but according to this economic report provided by the Association for Unmanned Vehicle Systems International (AUVSI) in 2013 more than 80% of civilian drone applications will be connected with precision agriculture (PA), creating many new jobs and billions in market value.

San Francisco Circuits took a look at the growing precision agriculture industry with a supplier and expert in this field, Michal Ruš of e-Dron. “We believe that a low-cost drone can be effective tool for precision agriculture. Our Skyhunter fixed wing configuration (under 2000 EUR) is able to map an area of 150 hectares in less than 30 minutes.”

A few hours after the drone’s flight and scan, an accurate orthophoto map and 3D surface model with RGB and NDVI imagery is created. Such models/images can be exported directly into farm management programs and variable rate prescription maps.

By providing a service-based operation instead of drone ownership, e-DRON believes it is able to remove the burden of operation, maintenance and certification of such drones by farmers. Farmers rely on timely and accurate data to make better decisions. They are focused on their crops and if drones are not bulletproof or easy to maneuver for anyone without proper training, it makes sense to leave its operation to service providers.

Skyhunter fixed wing with RGB and NIR camera dual configuration

Skyhunter fixed wing with RGB and NIR camera dual configuration

e-DRON is currently building such a bulletproof drone with the help of some consultation on custom PCB fabrication and PCB assembly from San Francisco Circuits.

Drone hardware and software. But what is the drone made of? The difference between a drone and a model aircraft/copter is the flight controller with autonomous features. In this case, the heart of the Skyhunter model consists of a Pixhawk autopilot developed jointly by the PX4 open hardware project and 3D Robotics.

The autopilot contains a six-layer PCB with isolated power nets for the main and safety processor. It’s a 1.6mm FR-4 board with 0402 standard components, minimum pitch of 0.2mm and 0.15mm spacing. Copper thickness and stackup are standard with 0.35um copper. The challenge in autopilot electronics is not the base technology, but to ensure highest quality throughout the complete production process from PCB manufacturing to assembly.

Pixhawk - advanced 32bit autopilot by 3D Robotics

Pixhawk – advanced 32bit autopilot by 3D Robotics

The payload itself consists of 2 consumer grade point-and-shoot cameras; one is the original RGB camera and the second is converted to NIR (near infrared).

The processing chain to obtain orthophoto/3D imaging of a desired piece of land has a pretty simple workflow. The mission starts with a drawing a polygon around the desired area in Mission Planner software. Once the mission is complete, the images are transferred to a powerful PC to process the remaining steps.

Depending on customer requirements, ground control points (GCPs) are measured with RTK GNSS (2cm accuracy) before the mission start. These points are then manually assigned together with images from the cameras on the software to produce an accurate geo-referenced orthophoto and 3D model. The NIR-produced orthophoto is then the most useful product for the farmers to spot the crop health immediately. Although more advanced sensors exist that would outrun the performance and accuracy of such a converted NIR camera, this is the lowest cost solution.

Applications in precision agriculture. Drone use in PA is all about saving inputs to farmers. Whether it’s an indication to use fewer pesticides, fertilizers or water for irrigation, PA will make billions of cost savings and greener food products.

The drones are good at monitoring crops for a very low relative price. When compared with satellites or manned planes/helicopters, low cost drones are cheaper and can be deployed every day, even in a cloudy day. The farmers have no other cost effective way to scout their large fields than by drones. Other than the RS detection of the crop health, drones are already able to effectively manage fields by crop dusting with variable rate technology.

Future of drones in PA. Multi-sensor drones with more advanced micro-sensors (like hyperspectral, thermal, LiDAR, etc.) and smart zonal auto-classification analytics are in development.

Swarm operations (multiple drones) with continuous remote sensing (day passive sensors and night active sensors) for larger fields and applications are all viable for scaling.

Powering the drones using solar energy with hydrogen fuel cell technology (unlimited endurance, 24/7 operation), making instant real-time cloud processing of acquired data streamed via high-bandwidth telemetry (no need for many SSD/HDDs onboard of multi-sensor drones) is also a very real application. Drones may eventually be programmed to automatically take actions of the whole lifecycle – from RS detection to immediate application of inputs. Harvest or seeding may be the next drone activity.

The future is in the sky!