I’m trying to tune my Ranger 2000 for auto and FBWB and the problem I experience is with pretty big turn radius. When flying manually, it’s possible to do a pretty sharp turns, almost on spot, by adding elevator, and not lose altitude, but all FBWB and Auto do is rev up the throttle. Is there any way to force them to use elevator?
I set roll angle to 65 degrees and wp_radius to 20m and the plane still behaves like a pregnant cow.
Have you tuned your aircraft completely? have a look at the navigation tuning - http://ardupilot.org/plane/docs/navigation-tuning.html
This might help.
I have followed the instructions and tuned the plane. I dropped NAVL1_PERIOD to 16 which did help a bit, but it still tries to keep the altitude by revving the throttle and does not use elevator at all from what I can see.
Take a look at your TECS parameters. If you feel your roll tuning is sluggish,try increasing your P value and proportionately increasing your D value to remove any oscillations you may encounter.
#1 thing to check is if your ATT.rll and ATT.desrll (desired and actual roll) are aligned. If they’re not, fix that first. If your plane is not demanding 65 degrees during turns, then focus on the steps below. I do NOT recommend changing P and D values maually. Leave that up to autotune. It does a really good job if you follow the procedure.
#2 You need more bank to make the turn radius lower. Turn down your L1 nav period. That will likely make the turns more aggressive. My very-well tuned airframe uses 9. The WP_rad is not the diameter of your turns; it’s the distance from the waypoint at which point the plane will switch to the next flight line. I use roughly 35 on my plane that crusises at 18m/s.
#3 Watch out for the stall prevention code. If your airspeed is not high enough, that will limit the bank no matter what the navigation controller demands. Consider turning it off briefly if you think it may be limiting the bank angle.
#3 PTCH2SRV_RLL is probably the parameter you’re looking for when you say “Is there any way to force them to use elevator?” The parameter is really used to keep the plane from falling nose-down during turns though. It sounds like you really need more bank. 65 degrees is a lot of bank though… 60 pulls 2g’s if you stay level, and it goes up exponentially from there.