Alt-Hold climbing, but can't find the sweet "P" spot

Are you sure that you don't just have your throttle set outside of the dead band when you enter alt-hold? I had a quick look at your log and it seems that you hover at a throttle position over 60% If you switch to alt-hold while hovering then your copter will immediately start to rise unless you lower the throttle back into the dead band near centre (40-60%). The down side of doing this is that you will have to remember to raise the throttle when you exit alt-hold mode otherwise you will loose altitude unexpectedly.

From the troubleshooting guide:

My copter slowly rises or descends when I enable Alt-Hold or Loiter

The throttle deadband when in alt-hold or loiter mode is from 40% ~ 60% of the throttle. If you have an overpowered or underpowered copter then when in stabilize mode the throttle required to maintain a hover may be outside this range. So when you engage alt-hold or loiter your throttle is outside of the deadband and arducopter thinks you want to climb or descend. The simple solution is to move your throttle back to center as you engage alt-hold. A permanent solution is to modify the THR_MID parameter through the mission planner's Adv Parameter List screen. If your copter hover at 40% of throttle stick when in stabilize mode, make THR_MID = 400. If it hovers at 60% of throttle make the parameter 600, etc.

Replies

Bruno Bedard May 20, 2013 at 8:09pm

Hi Tony,

In the "Standard Params" near the bottom of the list, it's called "Telemetry startup delay (TELEM_DELAY).

Bruno
James Overington May 20, 2013 at 7:07pm

Are you sure that you don't just have your throttle set outside of the dead band when you enter alt-hold? I had a quick look at your log and it seems that you hover at a throttle position over 60% If you switch to alt-hold while hovering then your copter will immediately start to rise unless you lower the throttle back into the dead band near centre (40-60%). The down side of doing this is that you will have to remember to raise the throttle when you exit alt-hold mode otherwise you will loose altitude unexpectedly.

From the troubleshooting guide:

My copter slowly rises or descends when I enable Alt-Hold or Loiter

The throttle deadband when in alt-hold or loiter mode is from 40% ~ 60% of the throttle. If you have an overpowered or underpowered copter then when in stabilize mode the throttle required to maintain a hover may be outside this range. So when you engage alt-hold or loiter your throttle is outside of the deadband and arducopter thinks you want to climb or descend. The simple solution is to move your throttle back to center as you engage alt-hold. A permanent solution is to modify the THR_MID parameter through the mission planner's Adv Parameter List screen. If your copter hover at 40% of throttle stick when in stabilize mode, make THR_MID = 400. If it hovers at 60% of throttle make the parameter 600, etc.

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