Operations

How to operate the GRYFN Precision Tracking Module

Overview

A typical flight with the GRYFN Precision Tracking module will follow a simple workflow:

1. System power-on and APX-15 configuration

2. Takeoff

3. INS Alignment

4. Flight Mission

5. INS Alignment

6. Landing

7. APX-15 data download

APX-15 Configuration and Data Logging

Login

In order to access the APX web interface, a 10/100 BaseT Ethernet connection is provided. The APX is configured with a Static IP = 10.0.65.100 and the web interface can be accessed at that address. The network interface on the client machine should be set to a static IP of 10.0.65.2, for example.

Default Web UI login credentials are listed in the table below.

Username	Password
admin	password

INS Configuration

Because the Tracking Module and GNSS Antenna may be installed in different orientations on different UAVs, care should be taken to ensure the INS lever arms and mounting angles (Receiver Configuration -> INS) are correct for your system. Configurations for the Phantom 4 Pro and Mavic 2, as shown in the Installation section of this manual, are given below.

Parameter	DJI Phantom 4	DJI Mavic 2
Reference to IMU Angle X	-90	0
Reference to IMU Angle Y	90	0
Reference to IMU Angle Z	0	0
Reference to GNSS Lever Arm X	0.000	-0.075
Reference to GNSS Lever Arm Y	0.060	-0.015
Reference to GNSS Lever Arm Z	-0.035	-0.105
Reference to IMU Lever Arm X	0.000	-0.050
Reference to IMU Lever Arm Y	-0.100	0.000
Reference to IMU Lever Arm Z	0.080	-0.080

The APX-15 saves INS configuration, so it only needs to be changed if the nominal mounting angles or GNSS antenna positions have changed. This step can be skipped for subsequent flights with unchanged nominal sensor/antenna orientations.

Data Logging

The APX-15 in the GRYFN Tracking Module records data internally to a solid-state drive. Data logging parameters can be set in the Data Logging -> Summary -> DEFAULT "Data Logging Configuration" Page. The standard GRYFN logging configuration is shown below.

Data Logging Configuration for automatic logging with 2min duration files in the internal file system

The user may choose a different Schedule or Duration or choose to disable "Auto Log", which will require the user to enable data logging on the Data Logging -> Summary page before each mission.

Auto Logging

With "Auto Log" enabled, the APX will start recording raw navigation data as soon as GPS/GNSS lock is acquired. In most situations this is desirable. However, the user may want to manually control data logging if, for example, the system will be stationary on the ground for a long period of time before the mission. Long periods of static INS data may require trimming in post-processing.

The Data Logging -> Summary page will show the logging status and allow the user to manually stop logging after a mission.

Be sure to disable/stop logging before shutting down the APX or file corruption may occur.

APX-15 Data Logging Summary showing active internal logging

Takeoff

Due to the weight of the GRYFN Tracking UAV and the small UAVs it is employed on, special care should be taken for the UAV liftoff. Ensure the UAV is on a level, even surface and lifts off the ground quickly to avoid possible dragging and tip-overs.

Dynamic Alignment

In order to post-process navigation data from the INS, POSPac must align the accelerometer and GNSS measurements. This process necessitates a large horizontal motion of the INS in the beginning of the trajectory (before mission). Because post-processing is done forwards and backwards, a dynamic alignment after the mission is suggested as well, though not required.

An example of a dynamic alignment could be:

• Fly at max acceleration for ≈10seconds, then max deceleration to a stop, then turn 180 degrees and fly back to your start point.

• Fly a figure 8 pattern

Post-processed trajectory will not be exported until POSPac can align the INS

Flight Mission

Once a dynamic alignment has been performed the system can be flown to meet the mission requirements. Long periods of static motion may degrade the performance of the system, so it is recommended to keep the Tracking Module/UAV moving if possible.

Landing

Similarly to landing, care should be taken to ensure the UAV is on a level, even surface on landing to avoid possible dragging and tip-overs.

Data Download

Raw INS data can be downloaded via the Applanix Web UI Data Logging -> Data Files page. This page allows download and deletion of individual .T04 files. T04 files can be downloaded and processed directly in POSPac.

APX-15 Data Files