Downfacing lidar can be used for landing

Arducopter have lot of baro drift over long time flying about 10 to 15m (+ or -) altitude value .
Prevent this is there is any method available using downfacing lidar when copter come within lidar range it should take lidar value instead of barometer value by default.

It is the normal use of down facing lidarā€¦ Benewake TF02-Pro is fine below 30 meters, TFmini-Plus is 0K below 7 meters.

As soon as you reach working range of Lidar, it take control of height above ground.

So when detect lidar range reading Arducopter code automatically switch over to lidar altitude reading instead of baro altitude?.

I am using TF03 180m for terrain follwing and I want same lidar to be using landing also.

Nothing more to do. The same setting is used for both use.

To be clear it never ā€œswitchesā€ from baro to lidar. It weights them depending on the rangefinder gain value. It always looks at the baro, but will lean on the lidar more as it gets into range. You can set the rangefinder as your main alt source, but itā€™s not recommended as it will track even small changes in ground height like bushes, etc.

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Here is Alt Hold with a TF Mini Plus on Arducopterā€¦No complaints here, altitude is maintained very well.

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Hi Ricky your copter looks stable. May I know your setting of the lidar, like Scaling, max. range (during day time). Do you use 1 for scalling? Thank you

Hey Tony.

Here are all my parameters.
Please keep in mind that GNDCLEAR is specific to my quad. I have 4 TF miniā€™s in use on various machines. I find the alt hold and poshold for altitude is very solid as yo can see from the video.
TF Mini Plus on I2C.
Here is my hexa running lines down the field. Althold is AWESOME with the TF Mini. IT works super great.


Well done Ricky, so your range finder still good at 6 meter correct. I plan to use TF02 pro for altitudee (40 m according to and TF mini plus for object avoidanceā€¦Do you use I2C port for this Lidar?
Another question, do you have alert /error messages as you set RTL higher than max.range of the range finder1 ?

Hey Tony.
Yes Itā€™s pretty good to around 6 metersā€¦ Sorry I forget the max distance, but 6 meters is about max distance. Mine is I2C but I have them on machines in both formatsā€¦uart and i2c.
The 02 version will give yo a lot more rangeā€¦just rememberā€¦brochure numbers and reality are not the same. lol

Another question, do you have alert /error messages as you set RTL higher than max.range of the range finder1 ?

An alertā€¦no not that I have ever seen. I never noticed anything in the logs eitherā€¦it just comes back and lands.
I will run some rtl tests tomorrow if the weather is good and see if anything stands out.

Today I had a Lidar Failureā€¦not real failure but more a bad connection to the I2C buss for the lidar. So the rangefinder was not found. I will repair the loose wireā€¦But the reason I mention it is how poorly the quad held altitude with out it. Where I fly there is a slight slope up going to the west and as I was zooming down the field with that confidence I have with the lidar working. I suddenly realized I was about to strike the ground and had to throttle up to avoid the crash. I was struck by just how well the lidar keeps me out of trouble on this field.

I miss you Lidarā€¦I will fix you today.

Hi Ricky,
Sorry to hear that accident, I hope the damage is not seriousā€¦
Back to my question about the alert, I set my RTL altitude to be 20 m (or more), but my TF mini (temporary I use TF mini for testing) max. range is only 6 m. In this condition I got alert that avoid me from arming. The message is: "pre-arm, RTL altitude is higher than range finder max. range . (I set the ARMING parameter to : All (or 0 value), which mean all condition must be checked by the ardupilot.
Solution is, I ignore this precondition of ARMING. Then I can do arming. Do you experience this issue??? Basically my copter can fly well.

Hey Tony.
No worries there was no crash. I pulled up in time. I was just illustrating how comfortable I got with the TF mini working.
As for your error. I canā€™t say I have ever encountered this one.
My RTL Alt is set right now to the default 1500ā€¦or 15 meters which 9 meters higher then my Max Lidar height. I get no such error.
I wonder if @ppoirier Patrick might know what this is.

I would check on the logs, specifically to rangefinder distance to see if it generate ā€˜falseā€™ distance corresponding to Max Distance as you set to 15 Meters. If thatā€™s the case it is really bad for this use caseā€¦ and it require opening an issue

Well dang I think my TF Mini Plus has packed it in.

TF Mini Replacedā€¦damn thats the second one that has failed.

Weird , I have not experienced any failure of the Ā± 20 installed and tested

Ya I know its very odd indeed.