When I engage RTL, the plane descends (seems to be in order to reach set altitude of about 225 ft.) by cutting the throttle and then engages the throttle to compensate the altitude loss… It then flies for a short time before increasing throttle to full and increases altitude then repeats the throttle cut and loses altitude again (rinse and repeat)…
It is returning and loitering so it is technically doing its job, but I want it to specifically not use airspeed to adjust altitude. I would like it to use the elevator to adjust altitude. The airplane is very heavy and I need it to have full or close to full throttle (80-100%) during rtl at all times. Does anyone know specifically what parameters control throttle, alt., air/groundspeed and their relationships? It would be nice to set a specific airspeed or throttle percentage when rtl is engaged and not deviate with large throttle decreases and increases. When I engage the heading/altitude hold the airplane is solid as a rock! So i know the apm has the capability to be more accurate. Also, the airspeed sensor is installed mut disable. (I wanted to get rtl working properly without the pitot tube before I add any more complications to the mix.
Thanks very much!
P.S. I would send datalogs, but im also having problems with that so i will post that question separately (datalogs just show a long list of neverending scrolling code when i try to upload them to analyze… and my computer beeps loudly repetitively)…
[quote=“brandom79”]When I engage RTL, the plane descends (seems to be in order to reach set altitude of about 225 ft.) by cutting the throttle and then engages the throttle to compensate the altitude loss… It then flies for a short time before increasing throttle to full and increases altitude then repeats the throttle cut and loses altitude again (rinse and repeat)…
It is returning and loitering so it is technically doing its job, but I want it to specifically not use airspeed to adjust altitude. I would like it to use the elevator to adjust altitude. The airplane is very heavy and I need it to have full or close to full throttle (80-100%) during rtl at all times. Does anyone know specifically what parameters control throttle, alt., air/groundspeed and their relationships? It would be nice to set a specific airspeed or throttle percentage when rtl is engaged and not deviate with large throttle decreases and increases. When I engage the heading/altitude hold the airplane is solid as a rock! So i know the apm has the capability to be more accurate. Also, the airspeed sensor is installed mut disable. (I wanted to get rtl working properly without the pitot tube before I add any more complications to the mix.
Thanks very much!
P.S. I would send datalogs, but im also having problems with that so i will post that question separately (datalogs just show a long list of neverending scrolling code when i try to upload them to analyze… and my computer beeps loudly repetitively)…[/quote]
That’s exactly the way that all my airplanes fly with some of the default parameters.
First make sure you have good PID tuning (run autotune). If you have an airspeed probe make sure you have flown a calibration flight then turn off the calibration parameter (ARSPD_AUTOCAL back to 0)
Change TECS_SPDWEIGHT from the default of 1.0 to 0.1
That will make a huge improvement.
If you fly waypoint missions reduce GLIDE_SLOPE_MIN from the default (15) to a smaller number (usually 1 to 4 will do the trick).
Also activating the EKF will improve all flight modes. That filter is only available if you have a Pixhawk as the old APM does not have enough computing power. AHRS_EKF_USE = 1
Well, I tried changing the tecs_spdwght to .1, 0, 1.5, and 1.9… I think a higher number actually worked better. After engaging the RTL the plane still rollercoasters but smooths out within reason after a couple ups and downs. I believe this may be due to transitional lift. (When the plane speeds up it climbs and noses down when slowing) Perhaps this is why the rollercoaster is happening. Now I need to find the setting to trim the elevators up and down in relationship to the throttle/speed. (hmmm… would I be able to set the auto elevator trim in relationship to the speed and not throttle?)