I've been running the APM board in simulation mode with a HIL setup for about two weeks now and am consistenly seeing the altitude Error end up about 10 meters below the target.
It settles there just fine and seems to be happy knowning that it's low and doesn't try to correct itself.
I still have the default config parameters and was wondering what I should tweak to start addressing the problem.
I have the latest versions of APM and the Mission Planner as of this writing.
Thanks,
Andrew
Replies
Hi Andrew,
This is a tuning issue. There are two parts to consider. First, the cruise airspeed and the cruise throttle values chose must match for altitude hold to work well. If your cruise throttle value is too low for your chosen airspeed, then the throttle control loop is always having to work to raise the throttle. Also, the default gain values for the throttle control loop have P gain only. Wiith only P gain and a steady state disturbance (in this case the nominal throttle value being too low) you will have a steady state error.
1 - Tune your pitch loop for good airspeed hold first
2 - Adjust the cruise throttle value to be the correct throttle for your desired airspeed
3 - Tune the throttle control loop gains.
Those steps will get you a good altitude hold.