Steps to build a DIY low-cost fixed-wing drone for biodiversity conservation

it is necessary to define the positioning of all components and possible modifications of the air- frame considering the drone balance from the center of gravity. The modifications we made to the airframe (hole at the bottom for passing the camera lens, hole at the top for passing the GNSS cable and elimination of some internal structures for positioning the battery and flight controller) were carried out taking into account the balance of the drone (See Item 2 in S2 Text). Some fixed-wing airframe models have markings that indicate the center of gravity where the drone can be balanced and are usually found below the wings. We recommend that the center of gravity of each airframe is found and the modifications and positioning of the components are carried out from there (See Item 13 in S5 Text). III. Setup flight controller. The mRo Pixhawk 2.4.6 flight controller is the command cen- ter of the drone that makes the link between the main components, the sensors and the GCS, so its configuration is one of the most important parts in the drone development. Initially we must make the connections on the Pixhawk of all the components necessary for its operation (See Item 1.2 in S2 Text). Then we must perform the installation of the GCS software to start the update, calibration and setup of the internal and external sensors of the flight controller (See Item 2 in S3 Text). Once the components are connected and the GCS software is installed, we start the follow- ing steps (Fig 3): Firmware update (See Item 3 in S3 Text); Airframe setup (See Item 4 in S3

Text); Sensor setup (See Item 5 in S3 Text); RC setup (See Item 6 in S3 Text); Flight modes configuration (See Item 7 in S3 Text); Power calibration (See Item 8 in S3 Text); Safety config- uration (See Item 9 in S3 Text); and Camera setup (See Item 10 in S3 Text) within the QGroundcontrol software. We recommend that the processes mentioned above are performed in the same order in which they appear, since in some test configurations some problems occurred when performed differently. During the execution of each of these processes, we may encounter some unusual situations concerning the configuration of the flight controller (See S4 Text). Fig 3. Steps for setup flight controller. https://doi.org/10.1371/journal.pone.0255559.g003 PLOS ONE Building a DIY low-cost fixed-wing drone for biodiversity conservation PLOS ONE | https://doi.org/10.1371/journal.pone.0255559 August 13, 2021 7 / 17