altb_pmic
Testing ekf implementation for Quadro_1.
EKF_RPY.cpp
- Committer:
- pmic
- Date:
- 2019-10-24
- Revision:
- 16:c39e084f05ed
- Parent:
- 15:53485bd1ff28
- Child:
- 17:1d98928f7681
File content as of revision 16:c39e084f05ed:
#include "EKF_RPY.h"
using namespace std;
using namespace Eigen;
EKF_RPY::EKF_RPY(float Ts, float mx0, float my0, float mz0)
{
this->Ts = Ts;
set_para();
m0 << mx0, my0, mz0;
reset();
}
EKF_RPY::EKF_RPY(float Ts)
{
this->Ts = Ts;
set_para();
reset();
}
EKF_RPY::~EKF_RPY() {}
void EKF_RPY::set_para()
{
/* [n_gyro; n_v; n_b_g] */
var_fx << 0.1f, 0.1f, 0.1f, 0.002f, 0.002f, 0.002f, 0.002f, 0.002f;
/* [n_acc; n_mag] */
var_gy << 40.0f, 40.0f, 1.0f, 1.0f;
rho = 1.0f;
kv = 0.5f; /* k1/m */
g = 9.81f;
}
void EKF_RPY::reset()
{
u.setZero();
y.setZero();
x.setZero();
update_angles();
calc_F();
calc_H();
initialize_Q();
initialize_R();
P = Q;
K.setZero();
I.setIdentity();
e.setZero();
}
void EKF_RPY::set_m0(float mx0, float my0, float mz0)
{
m0 << mx0, my0, mz0;
}
float EKF_RPY::get_est_state(uint8_t i)
{
/* x = [ang; v; b_g] = [0: phi
1: theta
2: psi
3: b_gx
4: b_gy
5: b_gz
6: vx
7: vy] */
return x(i);
}
void EKF_RPY::update(float gyro_x, float gyro_y, float gyro_z, float accel_x, float accel_y, float magnet_x, float magnet_y)
{
u << gyro_x, gyro_y, gyro_z;
y << accel_x, accel_y, magnet_x, magnet_y;
update_angles();
calc_F();
calc_H();
calc_Q();
x = fxd();
P = F * P * F.transpose() + Q;
e = y - gy();
// K = P * H.transpose() * ( H * P * H.transpose() + R ).inverse();
// x = x + K * e;
// P = (I - K * H) * P;
/* only valid if R is diagonal (uncorrelated noise) */
for(uint8_t i = 0; i < 4; i++) {
K.col(i) = ( P * (H.row(i)).transpose() ) / ( H.row(i) * P * (H.row(i)).transpose() + R(i,i) );
x = x + K.col(i) * e(i);
P = (I - K.col(i)*H.row(i)) * P;
}
}
void EKF_RPY::update_angles()
{
s1 = sinf(x(0));
c1 = cosf(x(0));
s2 = sinf(x(1));
c2 = cosf(x(1));
s3 = sinf(x(2));
c3 = cosf(x(2));
}
void EKF_RPY::calc_F()
{
F << Ts*(c1*s2*(u(1) - x(6)) - s1*s2*(u(2) - x(7)))/c2 + 1.0f, Ts*(c1*(u(2) - x(7)) + s1*(u(1) - x(6)))/(c2*c2), 0.0f, 0.0f, 0.0f, -Ts, -Ts*s1*s2/c2, -Ts*c1*s2/c2,
-Ts*(c1*(u(2) - x(7)) + s1*(u(1) - x(6))), 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, -Ts*c1, Ts*s1,
Ts*(c1*(u(1) - x(6)) - s1*(u(2) - x(7)))/c2, Ts*(c1*(u(2) - x(7)) + s1*(u(1) - x(6)))*s2/(c2*c2), 1.0f, 0.0f, 0.0f, 0.0f, -Ts*s1/c2, -Ts*c1/c2,
0.0f, Ts*c2*g, 0.0f, 1.0f - Ts*kv, Ts*(u(2) - x(7)), 0.0f, 0.0f, -Ts*x(4),
-Ts*c1*c2*g, Ts*g*s1*s2, 0.0f, -Ts*(u(2) - x(7)), 1.0f - Ts*kv, 0.0f, 0.0f, Ts*x(3),
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f;
}
void EKF_RPY::calc_H()
{
H << 0.0f, 0.0f, 0.0f, -kv, u(2) - x(7), 0.0f, 0.0f, -x(4),
0.0f, 0.0f, 0.0f, x(7) - u(2), -kv, 0.0f, 0.0f, x(3),
0.0f, - c2*m0(2) - c3*m0(0)*s2 - m0(1)*s2*s3, c2*(c3*m0(1) - m0(0)*s3), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
m0(0)*(s1*s3 + c1*c3*s2) - m0(1)*(c3*s1 - c1*s2*s3) + c1*c2*m0(2), s1*(c2*c3*m0(0) - m0(2)*s2 + c2*m0(1)*s3), - m0(0)*(c1*c3 + s1*s2*s3) - m0(1)*(c1*s3 - c3*s1*s2), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f;
}
void EKF_RPY::initialize_R()
{
R << rho*var_gy(0)/Ts, 0.0f, 0.0f, 0.0f,
0.0f, rho*var_gy(1)/Ts, 0.0f, 0.0f,
0.0f, 0.0f, rho*var_gy(2)/Ts, 0.0f,
0.0f, 0.0f, 0.0f, rho*var_gy(3)/Ts;
}
void EKF_RPY::initialize_Q()
{
Q << Ts*(var_fx(0) + (c1*c1*var_fx(2) + s1*s1*var_fx(1))*s2*s2/(c2*c2)), Ts*(var_fx(1) - var_fx(2))*c1*s1*s2/c2, Ts*(c1*c1*var_fx(2) + s1*s1*var_fx(1))*s2/(c2*c2), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
Ts*(var_fx(1) - var_fx(2))*c1*s1*s2/c2, Ts*(var_fx(1)*c1*c1 + var_fx(2)*s1*s1), Ts*(var_fx(1) - var_fx(2))*c1*s1/c2, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
Ts*(c1*c1*var_fx(2) + s1*s1*var_fx(1))*s2/(c2*c2), Ts*(var_fx(1) - var_fx(2))*c1*s1/c2, Ts*(c1*c1*var_fx(2) + s1*s1*var_fx(1))/(c2*c2), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, Ts*var_fx(3), 0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(4), 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(5), 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(6), 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(7);
}
void EKF_RPY::calc_Q()
{
Q(0,0) = Ts*(var_fx(0) + (c1*c1*var_fx(2) + s1*s1*var_fx(1))*s2*s2/(c2*c2));
Q(0,1) = Ts*(var_fx(1) - var_fx(2))*c1*s1*s2/c2;
Q(0,2) = Ts*(c1*c1*var_fx(2) + s1*s1*var_fx(1))*s2/(c2*c2);
Q(1,0) = Q(0,1);
Q(1,1) = Ts*(var_fx(1)*c1*c1 + var_fx(2)*s1*s1);
Q(1,2) = Ts*(var_fx(1) - var_fx(2))*c1*s1/c2;
Q(2,0) = Q(0,2);
Q(2,1) = Q(1,2);
Q(2,2) = Ts*(c1*c1*var_fx(2) + s1*s1*var_fx(1))/(c2*c2);
}
Matrix <float, 8, 1> EKF_RPY::fxd()
{
Matrix <float, 8, 1> retval;
retval << x(0) + Ts*(u(0) - x(5) + (c1*s2*(u(2) - x(7)))/c2 + (s1*s2*(u(1) - x(6)))/c2),
x(1) + Ts*(c1*(u(1) - x(6)) - s1*(u(2) - x(7))),
x(2) + Ts*((c1*(u(2) - x(7)))/c2 + (s1*(u(1) - x(6)))/c2),
x(3) + Ts*(g*s2 - kv*x(3) + x(4)*(u(2) - x(7))),
x(4) - Ts*(kv*x(4) + x(3)*(u(2) - x(7)) + c2*g*s1),
x(5),
x(6),
x(7);
return retval;
}
Matrix <float, 4, 1> EKF_RPY::gy()
{
Matrix <float, 4, 1> retval;
retval << x(4)*(u(2) - x(7)) - kv*x(3),
- kv*x(4) - x(3)*(u(2) - x(7)),
- m0(2)*s2 + c2*c3*m0(0) + c2*m0(1)*s3,
- m0(0)*(c1*s3 - c3*s1*s2) + m0(1)*(c1*c3 + s1*s2*s3) + c2*m0(2)*s1;
return retval;
}