Payload refers to air vehicle (aircraft) cargo. It is also defined as the amount of cargo weight an air vehicle can safely carry. Carrying a payload on board is the sole purpose for most UASs. Payloads come in a variety of sizes, weights, and functions. In our business of geospatial remote sensing, we focus on remote sensing sensors and the necessary navigation systems accompanying them. A UAS dedicated to remote sensing and mapping missions is usually equipped with one or more of the following sensors.
Auxiliary sensors here mean the navigation sensors that are necessary to determine the location and the orientation of the UAS and its remote sensors that are mentioned earlier in this section. For the UAS and onboard sensor position determination, the Global Positioning System (GPS) is used, and for the attitudes or orientation of the UAS and the onboard sensors, the Inertial Measurement Unit (IMU) is used.
The GPS does not need introduction, as everyone is familiar with its definition. It is the same GPS that you might use to drive around town. However, GPS that is used to determine a remote sensor position usually undergoes a post-processing to enhance the accuracy of the position.
UAS are offered with two grades of GPS accuracies. The most common one is the single frequency GPS receivers as it is cheaper, and it does not require post-processing or real-time correction service. Such receivers provide location accuracy of around 1 to 2-meter. For more accurate geospatial products generation, the more accurate dual frequency receiver and precise services are need needed. The latter receivers offer two modes of operations, both of which yield positional accuracy of 1 to 3 cm with little or no ground controls required for the project. UAS vendors are fielding systems with two operational modes, those are:
In principle, both RTK and PPK promise positional accuracies at the 1-3cm level. The main purpose of RTK and PPK is to minimize or eliminate the need for ground control points, thereby reducing cost. For more details on GPS, please visit GPS Defined. [18]
An inertial measurement unit, or IMU [19], is an electronic device that measures and reports on aerial vehicle velocity, orientation, and gravitational forces using accelerometers and gyroscopes. IMUs are typically used to control and maneuver manned aircraft, unmanned aerial vehicles (UAVs), and satellites. Another important use for the IMU is that it helps IMU-enabled GPS devices to maintain positioning information when GPS-signals are unavailable, such as in tunnels, inside buildings, or when electronic interference is present.
The IMU is the main component of inertial navigation systems (INS) used in aircraft, spacecraft, watercraft, and guided missiles in Geo-spatial mapping activities. The data collected from the IMUs sensors allows us to determine the orientation of the sensor, which is an important aspect in geolocating on the ground each pixel of the sensor. The IMU, like other components necessary for the operation of UASs, is miniaturized in weight and size to make it fit on small UASs. An example of these small IMUs, which are mainly designed for UASs, is the SBG 500E, [20] illustrated in Figure 2.12.
For more details on the IMU, you can visit the IMU Wikipedia page [19].
Links
[1] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/B4842_16MP_CCDCamera_Specs.pdf
[2] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/IXA180_IXA160.pdf
[3] https://geospatial.phaseone.com/drone-payload/p3-payload-for-drones/?utm_source=referral&utm_medium=eblast&utm_campaign=GEO-2021-05-05-Geoconnection-eblast-P3_payload_for_drones&utm_content=CTA
[4] https://geospatial.phaseone.com/drone-payload/
[5] https://www.imperx.com/bobcat-2-0-ccd/
[6] https://www.phaseone.com/
[7] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/PH_Geospatial_Overview_Deck_v5.pdf
[8] https://www.parrot.com/en/support/documentation/sequoia
[9] https://en.wikipedia.org/wiki/Electromagnetic_spectrum
[10] https://www.parrot.com/assets/s3fs-public/2021-09/sequoia_integration_manual_en.pdf
[11] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/flir-a6700sc-mwir-series-infrared-camera-datasheet.pdf
[12] https://www.flir.com/
[13] http://en.wikipedia.org/wiki/LIDAR
[14] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/DataSheet_VUX-1_14-02-2014_PRELIMINARY_4pages.pdf
[15] https://youtu.be/YaGw-dzo9Mc
[16] http://www.riegl.com/nc/
[17] http://velodynelidar.com/
[18] http://en.wikipedia.org/wiki/Global_Positioning_System
[19] http://en.wikipedia.org/wiki/Inertial_Measurement_Unit
[20] https://www.e-education.psu.edu/geog892/sites/www.e-education.psu.edu.geog892/files/IG-500E-Leaflet-1.pdf
[21] http://www.sbg-systems.com/