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Re: [Paparazzi-devel] Question about throttle control for fixed-wing air

From: Loic Drumettaz
Subject: Re: [Paparazzi-devel] Question about throttle control for fixed-wing aircrafts
Date: Wed, 13 Aug 2014 19:20:53 +0200

First of all: ins_neutral must be set so the plane flies at nominal (cruise) speed in auto1 mode. Then nominal throttle can be tuned for that speed: if you need 50% throttle to fly level in auto1 mode, then nominal throttle = 0.5.
For throttle_increment, the best way to tune it is in auto2:
- Use a flight plan where the plane can climb and go down at a given vertical speed.
- Using real time plotter, plot desired.climb versus estimator.zdot (vz  = climb = zdot)
- First tune pitch_of_vz to follow the desired climb.
- Then tune throttle_inc.  If the plane horizontal speed rises during climb and reduce during descent= too much throttle_inc.
- Once throttle_inc tuned you will have to fine tune pitch of vz, then tune again throttle_inc.

It's hard to observe if speed rises or decreases without airspeed sensor. You can read gps speed but it's groundspeed, not airspeed. One tip: If the airspeed is too low, the pitch angle (attitude.theta) will not reach the pitch setpoint (desired.pitch). If the speed is too high the pitch measure will overshoot the setpoint.
This is true, of course, if attitude pitch loop is already well tuned, but that's another subject...

Good flights!

Le 13 août 2014 16:09, "Chris Gough" <address@hidden> a écrit :
For v_ctl_auto_throttle_cruise_throttle I'd just trim the plane out in manual flight then make a guess after looking at a plot of the throttle (vs climb) from the telemetry log.

For v_ctl_auto_throttle_climb_throttle_increment, try 0.1 for a typical model, more if it's overpowered/acrobatic (maybe 0.2) and less if it's overweight (maybe 0.5). Hopefully someone will explain a better method to both of us.

Chris Gough

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