6.3 Safety Parameters

Safety section provides various configuration options for RPA safety.

Failsafe means including some mechanism for automatically mitigating the consequences of a potential source of failure. These ensure that if something goes wrong in the pathway, processes are in place to identify:

  1. What is going wrong?

  2. What action follows to ensure a safe outcome?

Failsafe should be a ‘closed loop’ process. Effective failsafe monitoring necessitates noting but the start and end points of essential activities (often via a systematic procedure and/or an IT system), as well as a mechanism to verify that all opened loops are closed within an adequate timeframe.

In the event that vehicle control is lost, Copter has a number of failsafe features in place to aid vehicle recovery and prevent wandering. These are the safety measures and therefore everyone should take utmost care of these failsafe. Failsafe which are to be considered are as follows:

6.3.1 Battery Failsafe Trigger

This section sets the Battery Failsafe parameters. You can set low and critical thresholds for voltage and/or remaining capacity and define the action if the failsafe value is breached. The thresholds can be disabled by setting them to zero. Following options are available for configuration.

  • Low action - Select one from

    • None,

    • Land,

    • RTL,

    • SmartRTL,

    • SmartRTL or Land,

    • Terminate.

  • Critical action - Select one from

    • None,

    • Land,

    • RTL,

    • SmartRTL,

    • SmartRTL or Land,

    • Terminate.

  • Low voltage threshold - Battery voltage that triggers the low action.

  • Critical voltage threshold - Battery voltage that triggers the critical action.

  • Low mAh threshold - Battery capacity that triggers the low action.

  • Critical mAh threshold - Battery capacity that triggers the critical action.

Note: The battery failsafe can only be reset if the device is rebooted after it has activated. Failsafe Trigger Ground Station Failsafe

The Ground Station Control (GCS) failsafe regulates how the Copter reacts if it loses contact with the GCS. When a GCS failsafe is triggered, the copter can be configured via parameters to do nothing, land immediately, RTL, or SmartRTL. It can also be configured to bypass the failsafe in an Auto Mode mission, bypass the failsafe in pilot controlled modes, or to continue landing if already in a landing phase. Throttle Failsafe

You can configure a software failsafe that is activated by setting on the throttle input channel using the throttle failsafe. PWM Threshold

Set the value of current as a PWM threshold ranging from 925 to 1100 Amps. RC Threshold

To set the RC threshold click on the "Set" button. Follow the instructions appearing on the screen to complete the process of setting RC threshold.

To set the PWM settings of RC follow the instructions that popped up on the screen as shown in the image below.

After adjusting all these threshold values, click on the "Update" button to update these values.

6.3.2 Return to Launch (RTL)

This section sets the RTL Mode behavior. The following configurations are available.

Select RTL return altitude:

  1. Return at Current Altitude - Return at the current altitude. Enable this option to return at the current altitude. If this option is enabled then the "return at specific altitude" option will be disabled.

  2. Return at Specific Altitude - Enable this option to set a specific altitude for returning the device. Ascend to a specified altitude to return if below the current altitude. Set the specific altitude value from 0 to 8000 cm.

  3. Loiter Above Home - Enable it to set a loiter time before landing from 0 to 60000 ms.

  4. Land Speed: Set the land speed with Descend speed from 30 to 200 cm/s.

  5. Final Land Altitude: After enabling this option, the user can set the final land Altitude from 0 to 1000 cm.

6.3.3 Geofence

This section sets the parameters for the cylindrical Simple Geofence. You can set whether the fence radius or height are enabled, the maximum values for causing a breach, and the action in the event of a breach. The configuration allows following settings.

  • Circle GeoFence enabled - Enable the circular geofence.

  • Altitude GeoFence enabled - Enable altitude geofence.

Fence Type:

Select the fence type from the given options such as:

  • Altitude: This allows to setup altitude fence so that RPA will be within defined altitude.

  • Circle: This defines circular type of fence.

  • Polygon: This defines polygon type of geo fence.

The user can select all or any one from the given options depends on the requirement of application.

Fence action may be any one from the following:

  • Report only - This option will provide the report of aa breach of the fence only. No action will be performed.

  • RTL or Land - On the breach of fence, the drone will enter into either Return To Home or Return to Land whichever is closer and safer to land.

  • Fence Maximum Altitude: This is the maximum altitude then RPA should go. If this limit is crossed, then fence action should get activated. The user can set the Fence altitude as minimum of 10 and maximum of 1000 m.



10 -1000


  • Fence Margin: Distance that autopilots should maintain from the fence to avoid a breach. This is the safety margin of fence. The minimum allowed value for fence margin is 1 m whereas the maximum of 10 m is allowed.

  • Circular Fence Radius: Circle fence radius which when breached will cause an RTL. Here you can define maximum radius of a circular fence. The radius for circular fence may vary between 30 to 10000 m.


30 – 10000


  • Fence Polygon Point Total: Here you can define maximum polygon points a fence should consider. Maximum of 20 polygon fence points are allowed.

Click on the Update button to update the settings done.

6.3.4 Arming Checks

The configuration options under this section are.

Arming Checks to perform (ARMING_CHECK) - Check all appropriate: Barometer, Compass, GPS lock, INS, Parameters, RC Channels, Board voltage, Battery Level, Airspeed, Logging Available, Hardware safety switch, GPS Configuration, System.

Barometer: the barometer sensor is reporting that it is unhealthy which is normally a sign of a hardware failure.

Compass: the compass sensor is reporting that it is unhealthy which is a sign of a hardware failure.

GPS Lock: the GPS is glitching and the vehicle is in a flight mode that requires GPS (i.e. Loiter, PosHold, etc) and/or the cylindrical fence is enabled.

INS: some or all of the accelerometer’s offsets are zero. The accelerometers need to be calibrated. Accels not healthy: one of the accelerometers is reporting it is not healthy which could be a hardware issue. This can also occur immediately after a firmware update before the board has been restarted. The accelerometers are reporting accelerations which are different by at least 1m/s/s.

One of the gyroscopes is reporting it is unhealthy which is likely a hardware issue. This can also occur immediately after a firmware update before the board has been restarted.

RC Channels:

Parameter: Auxiliary Function Switches are set to the same option which is not permitted because it could lead to confusion.

Board Voltage checks: The board’s internal voltage is below 4.3 Volts or above 5.8 Volts. If powered through a USB cable (i.e. while on the bench) this can be caused by the desktop computer being unable to provide sufficient current to the autopilot - try replacing the USB cable. If powered from a battery this is a serious problem and the power system (i.e. Power Module, battery, etc) should be carefully checked before flying.

Battery Level: If a power monitor voltage is below its failsafe low or critical voltages or failsafe remaining capacity low or critical set points, this check will fail and indicate which set point it is below. It will also fail if these set points are inverted, i.e. critical point is higher than low point.

Airspeed: If an airspeed sensor is configured, and it is not providing a reading or failed to calibrate, this check will fail.

Logging pre-armed was enabled but failed to write to the log.

Hardware safety switch: The Hardware safety switch has not been pushed.

GPS Configuration:

Note: When any Failsafe is activated and the failsafe action involves a mode change to the vehicle, it remains in that mode until the pilot changes the mode directly.

6.3.5 Parachute

This section sets the advanced safety i.e. parachute ejection. Under this setting there are parameters like parachute enabled, parachute type, parachute servo ON, parachute servo Off, parachute minimum altitude, parachute delay and parachute critical sink rate. By setting the values advanced safety feature can be used.

6.3.6 Terrain Settings

This feature allows the vehicle to climb or descend to maintain a specified distance above the terrain using SRTM data (aka terrain altitude data) provided by the GCS using a mapping service such as Google maps. To follow terrain data user, have to enable the parameters such as Enable Terrain and Terrain Follow switch. The Terrain enable parameter enable the terrain functionality and generate the Terrain folder in your Flight controller SD Card. Terrain follow parameter enables the terrain mode in RTL and Land mode. User can also set the radius using in Terrain Radius Text box and this radius is used to download the terrain file. When user enables the Follow Terrain Data switch, the GCS will generate and download the terrain file and that file is automatically get uploaded to the SD Card. The file is stored permanently into SD Card. To follow Terrain Data the Follow Terrain Data switch should be enabled, otherwise it won't follow Terrain functionality. Before enable Follow Terrain Data switch user have to select the location of Drone which used to download the terrain file. By enabling all these parameters, the vehicle will follow Terrain Data functionality.

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