How can I performed a valid Health Check flight?

• Purpose

The YellowScan systems are integrated in a way that the IMU and the scanner are maintained aligned even when dismantled from the UAV platform. Nevertheless, we recommend a yearly check to validate that the calibration angles remained stable.

If the unit has experienced a brutal shock during a crash or a hard landing, the system will likely need to be re-calibrated as the shock might have introduce a shift to the existing alignment. Depending on the intensity of the crash it might be essential to return the unit back for repairs where it will undergo a thorough check and calibration process. To complete the yearly health check calibration process, you will be required to fly over an area, adopting a certain flight plan as described below and transferring the data back to YellowScan support team who will be checking the calibration angles.

• Flight route

The calibration process produces the 3 attitude angles required to correct the alignment of the IMU relative to the scanner: roll, pitch and yaw. These angles are measured by comparing how 3D features display from one flight line to another. The calibration process therefore requires that:

1. the site contains 3D objects such as buildings (ideally with double pitched roofs)
2. the flight plan needs to be conducted according to a certain pattern (please see below the example)
3. 1 flight at several altitude, please see the table below depending on your system.
4. Flight speed will need to be set at 5m/s.
5. Several control points on flat surfaces, ideally intensity targets should be picked-up over the flown area with cm level accuracy method (RTK rod or theodolite). This will help the calibration process.

To complete the calibration flight plan, adopt the LiDAR Standard Operative Procedure as per a normal flight. This should include the IMU initialization method.

Best calibration angles are generated from flying over a double pitched roof building (see image below) following the flight plan described next.

Ideally, please send us the flight pattern by .kml/.kmz beforehand.

• Data Transfer

Once the flight has been completed, please gather the following data:

1. Raw LiDAR data and camera module photos if any.
2. Base station RINEX file (.YYO) with processed coordinates (Latitude, Longitude, Frame, Epoch)
3. Control Points (.csv or .txt) with EPSG code used
4. UAV and mounting used
5. Lever arms between the Antenna phase center and the Optical phase center of the scanner
6. Logfile (.txt, on the USB)
7. Configuration file (.txt, on the USB)

It is recommended to zip the files and use the below file transfer site to submit the data to the YellowScan support team. Select the email transfer and direct it to support@yellowscan.com

https://yellowscan.fromsmash.com/

Please send the request via our online form and we will handle the processing and compare to previous values. The calibration angles should be provided to you a couple of days later for a better usage of your unit.