Altitude hold

After adding a sonar I thought the altitude hold at lower altitudes would be good ( I wasn't even expecting perfect) but now the quad just starts descending at a slow rate (seems like as the battery drains it just settles-not sure if its related to the batteries) until touchdown in about 30 seconds. None of the posts I have seen are definitive on how to set up altitude hold for the non engineering types. If there was some kind of guide that directed me to the parameters etc. that are related to the altitude hold that would be a good start. Each post I have seen has a different attempted solution with very few saying they have solved the problem and have excellent altitude hold. It seems to me that the altitude hold is the basic most important feature that is required for most all other features. Until this works the other features are unusable. A simple step by step setup, defining the parameters that control the altitude hold would be a huge benefit. Maybe someone has got their altitude hold to work and has a list of parameters that were necessarily adjusted to make it stable.

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  • Hi Harley, I too have had this trouble. I have a quad and a hexa and both are doing the same as yours. I switch to Alt hold and the copter descends slowly until it touches the ground. I'm not sure if it is coincidence or not but it seemed to start doing it after I upgraded the firmware to 2.9.1. However is saying that I have reverted back to several different versions and have not been able to get it to work again. It is almost as if Alt Hold is doing a "land" maneuver  I know my alt hold gps/barometer are working as RTL works fine. 

    I have currently removed my sonar sensors and am relying on only the barometer. Until the problem arose altitude was quite stable. 

    I have uploaded my parameters for the quad if anyone is interested in having a look. 


    Quad Param bit slugish but good. alt issues.param

  • What firmware do you fly? Arducopter 2.9.1?

    Looks like there was a change in the Altitude Hold Mode for firmware 2.9.1.

    The limits for changing the altitude in Altitude hold mode are much narrower than in previous versions.

    Make sure your throttle stick is in center position!

    Try to add some altitude when the copter starts to descending.

    Try also to increase the alt hold gain.


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