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SITL: avoid FPE when running fly.ArduPlane

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Program received signal SIGFPE, Arithmetic exception.
__expf_finite () at ../sysdeps/x86_64/fpu/e_expf.S:132
132     ../sysdeps/x86_64/fpu/e_expf.S: No such file or directory.
(gdb) u
This commit is contained in:
Peter Barker 2017-08-30 14:39:24 +10:00 committed by Andrew Tridgell
parent b5e206f72f
commit 85ebe923b6
1 changed files with 8 additions and 1 deletions
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9
libraries/SITL/SIM_Plane.cpp
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@ -90,7 +90,14 @@ float Plane::liftCoeff(float alpha) const
const float M = coefficient.mcoeff;
const float c_lift_0 = coefficient.c_lift_0;
const float c_lift_a0 = coefficient.c_lift_a;
// clamp the value of alpha to avoid exp(90) in calculation of sigmoid
const float max_alpha_delta = 0.8f;
if (alpha-alpha0 > max_alpha_delta) {
alpha = alpha0 + max_alpha_delta;
} else if (alpha0-alpha > max_alpha_delta) {
alpha = alpha0 - max_alpha_delta;
}
double sigmoid = ( 1+exp(-M*(alpha-alpha0))+exp(M*(alpha+alpha0)) ) / (1+exp(-M*(alpha-alpha0))) / (1+exp(M*(alpha+alpha0)));
double linear = (1.0-sigmoid) * (c_lift_0 + c_lift_a0*alpha); //Lift at small AoA
double flatPlate = sigmoid*(2*copysign(1,alpha)*pow(sin(alpha),2)*cos(alpha)); //Lift beyond stall