Is Litchi mission information run by the controller or uploaded to the drone for self-execution?

[vindibona1]

Another thread piqued my interest in how instructions are executed in flight on various Litchi missions. While not legal to fly without VLOS, the question came up about flying up over a ridge of a mountain. Obviously in this instance you'd lose VLOS and probably lose signal from the controller. So my question, asked two ways is: If a programmed mission took the drone out of VLOS (i.e. on the other side of a large building) where you'd almost definitely lose signal, would the drone continue on the mission to completion? Or would the mission auto-cancel and throw it into the RTH mode? The second part of the question is: Are the Litchi mission instructions, once the mission has begun, stored on the controller and executed as the drone goes through the mission (from the controller) or is the entire mission uploaded to the drone itself somehow so the mission is excuted autonomously by the drone itself with the controller only being able to pause or stop the mission?

 

[slup]

The Litchi app store the waypoint mission on the AC ... but if you want it to proceed a mission when loosing the RC connection or if you want it to initiate the set failsafe RTH action is entirely your choice.

Go into the Litchi settings here ...



Then under the tab Aircraft choose the way you want it to behave here ...



Here what the manual says ...

 

[Mossiback]

Since the mission is uploaded to the AC, Litchi will try to complete the mission if connection to the RC is lost unless you use the exit option that @slup mentions above. Either way, many a Mavic have been lost due to this. Both Litchi or RTH can not compensate for a strong headwind on the return and will just fight it until a low battery forces a landing. Since there was no connection to the RC when lost and it could have been blown off the intended course, finding it without a Marco Polo type tracker would be difficult.

The likelihood of loss would be greater in your over the mountain scenario. You would need the RTH height set at higher than the ridge (you do not want to trust OA to protect your AC) and wind in the mountains can be highly variable.

 

[Dave Maine]

Note as well that neither Litchi or RTH work with GPS loss. GPS loss is relatively rare, but flying in canyons and other environments with narrow sky visibility situations Can happen.

 

[Facherty]

Also, whilst all the waypoints (heights and positions) are stored when the mission is uploaded, but two important things are not:

• the airspeed changes - if you slow down over the target area, and then lose contact with your drone, it will not receive the command to increase speed again. I try to set one speed for the entire mission, or at least ensure that its lowest speed will still allow it to return to home
• the gimbal movements - a result of your drone losing contact with the controller is that your film no longer looks at the object you wanted as it moves in the sky

That said, when I have lost contact on two longer missions, I was so happy to see the Third Twin return to me...

 

[vindibona1]

@Facherty Thank you. These things are so nuanced and even if documented are either buried or difficult to comprehend fully. Such a learning process this all it... Joyful- but consuming as well.