After the drone lands the props all spin up to 50% for about 0.5 sec just before dropping the props to idle speed. I am using a radio in Pos Hold mode and allowing the copter to land by reducing height till its landed. It lands perfectly and sits level with the props spinning at about 20% for a second or 2 then suddenly increases to 50% and lifts off just a few mm then drops the speed to about 10% as if in armed but not flying mode. Then it disarms after a few seconds. Does anyone know why it gives a sudden burst of thrust after it has landed. In the logs graph I see the landed_state status change from 2 to 1 at the same time as the sudden spin up. I am running Copter 4.6 on Speedybee mini. I had the same issue on Copter 4.5. I also see the same behaviour when I use the Land command in a Waypoint Mission.
Do others see this same issue. What is the cause?
I have just noticed that it does not happen in Stabilize mode. I can see the Landed_state transition from 2 to 1 and there is no sudden change in speed, the props just slows to idle speed. It must be a function of the position control.
Hi @TrevorTighe,
Thanks for the report. The issue is really that the position has likely drifted a little horizontally after the vehicle has physically touched the ground but before the landing detector has confirmed the vehicle has landed. During this period the vehicle will try and move horizontally but because it is physically unable to (because the legs are touching the ground) we get “I-term buildup” which just means the position controller tries harder and harder to move the vehicle. In very bad cases the vehicle can flip over so it’s good that in this case that is not happening.
Instead of Position Control mode, could you perhaps try Loiter mode? They’re very similar but Loiter gets more love.
Also ensuring the vehicle lands gently and/or using a better GPS may help.
Thanks for looking at this issue.
My final implementation is to use the RTL command in a mission. I can not see how I can use Loiter and RTL at the same time in a mission. I agree that there may be some integrator build up or similar but that should not be allowed to playout just at the moment that the mode changes from flying to landed. It should be a clean shutdown once Landed has been detected. This is not a case of slowly increasing in prop speed after landing but instead a jump increase in speed after its been stable for a couple of seconds and just when the Landed_state goes to 1. Integrator build up would cause it to increase speed slowly.
On a side note, is InternalError 0x100000 a possible cause of this issue or unrelated? It is always flashing on the Mission Planner screen.
Hi @TrevorTighe,
Detecting the landing is quite difficult but 4.6 includes extra logging to help get to the cause of the issue. The motors should definitely not speed up after it detects the landing and I don’t think is what’s happening. Instead it is before the landing is detected when the vehicle still thinks it’s flying but is actually touching the ground.
Internal Errors are never normal. InternalError 0x100000 is a “flow of control” error which means the code got into a place that it thinks it should not have. We’d definitely like to look into this if you’ve got an onboard log from AP-4.6 or 4.7
Thanks again for the reports!
I am having trouble down loading the logs from the controller. The green bar increases quickly at the beginning of the download but then slows to near no progress. I can get the tlog files from Mission planner but they are not as detailed. The Error 0x100000 happens as soon as I take-off in position hold mode.
The status screen shows errors_count2 jumps to 16 at the same time. I can upload my Params file if you think it maybe useful.
Hi @TrevorTighe,
Maybe take the SD card out of the autopilot, use an adapter to plug into your PC and then directly copy the logs from the card to your PC and upload the relevant one here?
Txs again for the report
You can also try updating Mission Planner to the latest Beta version form the Help Screen.