There are several scenarios where WingtraOne will take action by itself and engage a specific failsafe routine.
RTH is triggered automatically in these scenarios: geofence is violated; wind speed exceeds 12 m/s for 10 seconds; both telemetry and RC connection is lost for longer than holdout timer, or when the battery voltage drops below the threshold.
By default, RTH is triggered at 38% of battery, but an adaptive RTH can be triggered earlier at a value greater than 38% based on the time estimated for the drone to return to the home position. The factors that determine the adaptive RTH threshold are: absolute altitude of take-off location, distance to home position, the wind speed, wind direction, transition altitude, and RTH altitude.
Battery RTH is not triggered automatically when WingtraOne flies in assisted mode. A pop-up message warns the operator that action might be required.
Warnings are issued acoustically and visually on the tablet. The mission can still be continued, but caution is advised.
Emergency landing / hover down
This is the most extreme failsafe, as it forces WingtraOne to perform a back transition and land from the point the landing is triggered. It is triggered if the position of WingtraOne can not be defined. It can happen in the case of GPS loss or magnetometer failure. WingtraOne might drift, since the position is not controlled in this case. You can still take over manually by switching to assisted mode. If an accurate position estimation can be regained, emergency landing will be interrupted and RTH will be performed.
Last known WingtraOne location
The exact GPS coordinates of the last received position of WingtraOne can be displayed at any time. In the event of a crash, you can click on the "Last known WingtraOne location" option on the tablet to check the last known GPS location of WingtraOne.
From the cruise flight mode you can shift to a hover regime any time by pressing the assisted button and then the transition button on the remote control. When assisted-transition is triggered, WingtraOne will immediately change into its hover flight mode and stabilize itself in the air. Example situations when you should consider such a maneuver are:
- Unplanned approach of an object, e.g. helicopter, bird, etc.
- WingtraOne behaves abnormally or looks unstable in the air
- You simply need time to think about what the WingtraOne should do next
After you manage to get the WingtraOne into a safe situation, you can trigger the RTH function. The WingtraOne will then bring itself back to the home point and land safely autonomously. Note that once you enter assisted mode you can not resume the mission again until you return to home and re-power.
The emergency stop is a method of last resort used only in critical situations, because once activated there is no going back. The WingtraOne will cut power to both motors and activate one of the elevons to deflect at a high angle. This will cause a rapid descent with a tight spiral, which will crash land the drone. There is a high chance the drone will not be able to recover from an emergency landing. There are some extreme situations in which you might resort to using the emergency stop button to minimize risk, as follows:
- Prevent a motor burnout in the event of a tip over on the ground
- Failure of a single motor or part of the wing is damage— stopping the remaining motor will ensure the WingtraOne does not deviate into an unwanted direction
- A manned aircraft is approaching the WingtraOne at a very high speed—stopping the motor will prevent the WingtraOne from crashing into the manned aircraft and prevent any injury
- WingtraOne is very close to crashing into a building due to planning mistake or hardware failure— stopping the motor will prevent the WingtraOne from crashing into the building with the motor spinning and reduce the risk of injury