6.4 Settings of Safety Parameters
Safety section provides various configuration options for RPA safety.
RPA Configuration -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. 1.
    What is going wrong?
  2. 2.
    What action follows to ensure a safe outcome?
Failsafe should be a ‘closed loop’ process. Effective failsafe monitoring necessitates noting 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:

Battery Failsafe

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.
Battery failsafe settings for Critical Actions
  • 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.

Return to Launch

This section sets the RTL Mode behavior. Following configurations are available.
Select RTL return altitude:
  1. 1.
    Return at current altitude - Return at current altitude.
  2. 2.
    Return at specified altitude - Ascend to specified altitude to return if below current altitude.
  3. 3.
    Loiter above home for - Check to set a loiter time before landing. Select any one from the following:
  • Land with descent speed - Select final descent speed.
  • Final loiter altitude - Select and set final altitude for landing after RTL or mission (set to 0 to land).
RTL Settings

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.
RPA Configuration - Geofence Setting
  • Circle GeoFence enabled - Enable the circular geofence.
  • Altitude GeoFence enabled - Enable altitude geofence.
Fence action may be any one from the following:
  • Report only - Report fence breach.
  • RTL or Land - RTL or land on fence breach.
  • Max radius - Circular fence radius that when broken causes RTL.
  • Max altitude Fence maximum altitude to trigger altitude geofence.

Failsafe Trigger

Any failsafe will display a message and prevent arming. The configuration options under this section are:
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.
Ground Station Failsafe
  • If the copter is disarmed, no failsafe will take place.
  • If the copter is armed but has landed, the copter will immediately disarm.
  • If the copter is armed in Stabilize or Acro modes, and the throttle input is at minimum, the copter will immediately disarm.
  • Otherwise, the copter will take the actions as configured in the parameters described below.
If the failsafe clears the copter will remain in its failsafe mode. It will not automatically return to the flight mode that was active before the failsafe was triggered.
RPA Configuration - Failsafe Setting

Throttle Failsafe

You can configure a software failsafe that is activated by setting on the throttle input channel using the throttle failsafe.
Throttle Failsafe
RPA Configuration - Failsafe Setting
RPA Configuration - Failsafe Setting
  • GCS Heartbeat - Select one from Disabled, Warn only, Disarm, Enter depth hold mode, Enter surface mode.
  • Leak - Select one from Disabled, Warn only, Enter surface mode.
  • Detector Pin - Select one from Disabled, Pixhawk Aux (1-6), Pixhawk 3.3ADC(1-2), Pixhawk 6.6ADC.
  • Logic when Dry - Select one from Low, High.
  • Battery – Configure batter options.
  • EKF - Select one from Disabled, Warn only, Disarm.
Based on rate gyroscopes, accelerometer, compass, GPS, airspeed, and barometric pressure measurements, an Extended Kalman Filter (EKF) algorithm is used to estimate vehicle position, velocity, and angular orientation. An EKF also enables measurements from optional sensors such as optical flow and laser range finders to be used to assist navigation.
  • Pilot Input - Select one from Disabled, Warn only, Disarm.
  • Internal Temperature - Select one from Disabled, Warn only.
  • Internal Pressure - Select one from Disabled, Warn only.

Arming Checks

The configuration options under this section are.
RPA Configuration - Arming Checks
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.
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: Hardware safety switch has not been pushed.
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.
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Battery Failsafe
Return to Launch
Geofence
Failsafe Trigger
Throttle Failsafe
Arming Checks