Is this behaviour normal?

[icedfusion]

I have a hexacopter with an APM2.0 on it with GPS/Sonar.

Whenever I use ';loiter'; at a low height I am expecting the sonar to keep the copter at the height i engage it at (yes, I have enabled it and I can see the reading of 20cm when it is on the desk as per the manual).

However, when I do engage, it never stays at the set height and there is also quite a noticeable delay between switching modes - so much so that I will set it, then it will suddenly shoot off upwards instead of staying where it is at.

Then if I bring the throttle down, it basically falls out of the sky and if you give it more throttle/height it takes so long to respond it ends up crashing.

Is this loiter behaviour normal in the APM? Maybe I am just too used to the immediate reaction to gyro only?

ice.

[rickp]

I have a hexacopter with an APM2.0 on it with GPS/Sonar.

What version are you running? I';ve never had much luck with sonar so I took mine off. I will play with it once 2.9.92 is out and stable.

Have you done the heater and filter mods?

[rickp]

And which sonar sensor do you have?

[icedfusion]

Thanks for the replies - I have not done the heater/filter mod. I did a search for the filter mod - this is just for power? I am not sure that this would be my issue as I don';t think I have brown outs.

What is the heater mod?

My sonar is quite expensive and is one of the recommended ones I believe - I would have to check the exact model number. I think I might just bite the bullet and get an rctimer apm2.5 as the one I have is a first generation apm2.0 and it sounds like there have been some hardware improvements since.

Cheers

ice.

[rickp]

The sonar do not work below 10degC according to the specs, so the heater mod is essential if you';re in the UK. Some are using a ring from those LED strips to provide heat (red works best).

The filter reduces noise on the power supply to the sonar, which helps reduce the noise on teh output.

Its an analogue device, so I don';t think changing the APM will help - I';d work to reduce the noise, get it up to working temperature and see what you get then. It don';t be as good as baro-hold on the latest code but will still be useful when hovering low down...