void WindEKF::RungeKutta(float U[NUMU], float dT)
{
float dT2 =
dT / 2, K1[NUMX], K2[NUMX], K3[NUMX], K4[NUMX], Xlast[NUMX];
uint8_t i;
for (i = 0; i < NUMX; i++)
Xlast[i] = X[i]; // make a working copy
StateEq(U, K1); // k1 = f(x,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT2 * K1[i];
StateEq(U, K2); // k2 = f(x+0.5*dT*k1,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT2 * K2[i];
StateEq(U, K3); // k3 = f(x+0.5*dT*k2,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT * K3[i];
StateEq(U, K4); // k4 = f(x+dT*k3,u)
// Xnew = X + dT*(k1+2*k2+2*k3+k4)/6
for (i = 0; i < NUMX; i++)
X[i] =
Xlast[i] + dT * (K1[i] + 2 * K2[i] + 2 * K3[i] +
K4[i]) / 6;
}
void
WindEKF::RungeKutta(float U[NUMU], float dT)
{
// Output, Xnew, is written over X
// NOTE the algorithm assumes time invariant state equations and
// constant inputs over integration step
float dT2 =
dT / 2, K1[NUMX], K2[NUMX], K3[NUMX], K4[NUMX], Xlast[NUMX];
uint8_t i;
for (i = 0; i < NUMX; i++)
Xlast[i] = X[i]; // make a working copy
StateEq(U, K1); // k1 = f(x,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT2 * K1[i];
StateEq(U, K2); // k2 = f(x+0.5*dT*k1,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT2 * K2[i];
StateEq(U, K3); // k3 = f(x+0.5*dT*k2,u)
for (i = 0; i < NUMX; i++)
X[i] = Xlast[i] + dT * K3[i];
StateEq(U, K4); // k4 = f(x+dT*k3,u)
// Xnew = X + dT*(k1+2*k2+2*k3+k4)/6
for (i = 0; i < NUMX; i++)
X[i] =
Xlast[i] + dT * (K1[i] + 2 * K2[i] + 2 * K3[i] +
K4[i]) / 6;
}
