Is it possible to determine V speeds automatically for a given airframe? Vx, Vy, Vstall, Vmaxthrottle, etc? It would be helpful in its own right, but also for parameters that depend on these numbers, e.g.
ARSPD_FBW_MIN: Minimum airspeed demanded in automatic throttle modes. Should be set to 20% higher than level flight stall speed.
ARSPD_FBW_MAX: Maximum airspeed demanded in automatic throttle modes. Should be set slightly less than level flight speed at THR_MAX and also at least 50% above ARSPD_FBW_MIN to allow for accurate TECS altitude control.
If this auto-measuring functionality doesn’t exist yet, I wonder if it may make sense as a Lua script rather than a core part of the firmware, or if it could be a special type of mission, since you’d need to define a path along which you could do the measurement runs.
Certainly possible with scripting, we would definitely like a way to find them automatically. The high speed ones are slightly less risky, but bad things could potentially happen if you hit a stall and are not high enough and/or the aircraft its badly tuned.
Is there a straightforward way to detect a stall? I understand this isn’t something the autopilot really wants to deal with normally, that it would rather keep you from stalling in the first place. I see how adding a whole set of routines for stall detection and recovery would be a significant project.
But Vx, Vy, Vmaxthrottle should be easier, like you’re saying, plus a max endurance cruise and a max distance cruise.
Building up on the autotune function, I would continue the momentous calculation of the PID constants and check their error against the actual PID values. In the instance of a stall, I would expect the deviations between the two to grow rapidly. Then we would know there is a stall in progress because the aftermath of a stall is loss of control. Perhaps accelerometers could also supplement some of the information to minimize errors.