Inertial Navigation System (INS) for UAVs is a fully autonomous system that determines the location, speed, and orientation of a drone without using external signals such as GPS, radio beacons, or ground stations.

How It Works The system is based on the laws of inertia and consists of two main types of sensors, which are typically combined into an IMU (Inertial Measurement Unit) block:

• Accelerometers: measure linear acceleration along three axes.
• Gyroscopes: measure angular velocity (rotation around axes).

The system's computer continuously integrates this data: knowing the starting point and measuring every acceleration and turn, it "calculates" the current path of the object.

Setting the Starting Point Procedure

For the INS to work correctly, the operator must manually set the UAV's starting point. If the starting point has not been set, the system displays the message:

Please specify starting point to see UAV

Without performing this operation, launching the aircraft is impossible.

Setting the starting point allows the system to:

• determine the initial UAV position;
• activate inertial navigation;
• display the aircraft on the SkyHunter system map.

Open the map in the SkyHunter interface and click on the expected UAV launch point.

In the context menu, select the Set starting point command.

The system will automatically:

• set the point coordinates;
• determine the launch altitude.

If an active elevation map is enabled, the altitude is determined automatically. If the elevation map is inactive, the altitude must be set manually.

After confirmation, the UAV will be placed at the specified point on the map.

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UAV Position Correction

The main disadvantage of the Inertial Navigation System is error accumulation (drift). Over time, small sensor inaccuracies add up, and the drone's actual position begins to differ from the calculated one. Therefore, in modern UAVs, the INS typically works in conjunction with other systems for periodic coordinate correction.

Possible correction sources:

• radar data;
• visual orientation by map.

Changing UAV Position Based on Radar Data

If we have received data on the UAV's actual position from the radar and it differs from the INS data, we can correct the current position.

Click on the actual position location (received from the radar) and select the "I'm here" option in the context menu.

After this, the system will automatically correct the UAV position according to the new coordinates.

Correcting UAV Position Based on Radar Track

Binding to a radar track allows:

• improving positioning accuracy;
• compensating for inertial system drift.

To bind the UAV (marked in green) to a radar track, click on the blue aircraft (our position according to radar data) and click on the small aircraft icon located between the green and blue aircraft.

If everything went successfully and the track has been bound to the UAV, you will see the message "Target bind to UAV successfully" and the icon of our UAV will change.

After this, the radar track position is used as more accurate.

IMPORTANT! The inertial system is not recalibrated in this case, because frequent interference with INS operation can lead to unstable system behavior in the future. If at this moment our aircraft was executing a mission and flying toward a target, it will not immediately change its position according to the radar track: we calculate the error and account for it until reaching the target. Please note that for automatic coordinate refinement using the bound radar track, you must select the Radar navigation mode.