Diff: EKF_RP.cpp

Revision:

0:a0e9705be9c4

Child:

1:6b803652d032

diff -r 000000000000 -r a0e9705be9c4 EKF_RP.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/EKF_RP.cpp	Fri Oct 18 14:55:53 2019 +0000
@@ -0,0 +1,126 @@
+#include "EKF_RP.h"
+
+using namespace std;
+using namespace Eigen;
+
+EKF_RP::EKF_RP(float Ts)
+{
+    this->Ts = Ts;
+    /* [n_gyro; n_b_g; n_v] */
+    var_fx << 1000, 1000, 20, 20, 10, 10;
+    /* [n_acc] */
+    var_gy << 40, 40;
+    rho = 5000;
+    kv = 0.5;       /* k1/m */
+    g = 9.81;
+    reset();
+}
+
+EKF_RP::~EKF_RP() {}
+
+void EKF_RP::reset()
+{   
+    u.setZero();
+    y.setZero();
+    x.setZero();
+    update_F();
+    update_H();
+    initialize_Q();
+    initialize_R();
+    P = Q;
+    K.setZero();
+    I.setIdentity();
+}
+
+void EKF_RP::update(float gyro_x, float gyro_y, float accel_x, float accel_y)
+{
+    // u << gyro_x, gyro_y;
+    // y << accel_x, accel_y;
+    
+    // update_F();
+    // update_H(); /* H remains constant */
+    // update_Q();
+    
+    // x = fxd();
+    // P = F * P * F.transpose() + Q;
+    
+    // K = P * H.transpose() * ( H * P * H.transpose() + R ).inverse();
+    
+    // x = x + K * (y - gy());
+    // P = (I - K * H) * P;
+}
+
+float EKF_RP::get_est_state(uint8_t i)
+{   
+    /* x = [ang; b_g; v] */
+    return x(i);
+}
+
+void EKF_RP::update_angles()
+{
+    s1 = sinf(x(0));
+    c1 = cosf(x(0));
+    s2 = sinf(x(1));
+    c2 = cosf(x(1));   
+}
+
+void EKF_RP::update_F()
+{
+    F << (Ts*c1*s2*(u(1) - x(3)))/c2 + 1, -(Ts*s1*(u(1) - x(3)))/(s2*s2 - 1), -Ts, -(Ts*s1*s2)/c2,         0,         0,
+                    -Ts*s1*(u(1) - x(3)),                                  1,   0,         -Ts*c1,         0,         0,
+                                       0,                                  0,   1,              0,         0,         0,
+                                       0,                                  0,   0,              1,         0,         0,
+                                       0,                            Ts*c2*g,   0,              0, 1 - Ts*kv,         0,
+                             -Ts*c1*c2*g,                         Ts*g*s1*s2,   0,              0,         0, 1 - Ts*kv;
+}
+
+void EKF_RP::update_H()
+{
+    H << 0, 0, 0, 0, -kv,   0,
+         0, 0, 0, 0,   0, -kv;
+}
+
+void EKF_RP::initialize_R()
+{
+    R <<  rho*var_gy(0)/Ts,                0,
+                         0, rho*var_gy(1)/Ts;
+}
+
+void EKF_RP::initialize_Q()
+{   
+    Q << Ts*(var_fx(0) + (s1*s1*s2*s2*var_fx(1))/(c2*c2)), (Ts*c1*s1*s2*var_fx(1))/c2,            0,            0,            0,            0,
+                               (Ts*c1*s1*s2*var_fx(1))/c2,         Ts*c1*c1*var_fx(1),            0,            0,            0,            0,
+                                                        0,                          0, Ts*var_fx(3),            0,            0,            0,
+                                                        0,                          0,            0, Ts*var_fx(4),            0,            0,
+                                                        0,                          0,            0,            0, Ts*var_fx(5),            0,
+                                                        0,                          0,            0,            0,            0, Ts*var_fx(6);
+}
+
+void EKF_RP::update_Q()
+{   
+    Q(0,0) = Ts*(var_fx(0) + (s1*s1*s2*s2*var_fx(1))/(c2*c2));
+    Q(0,1) = Ts*c1*s1*s2*var_fx(1)/c2;
+    Q(1,0) = Q(0,1);
+    Q(1,1) = Ts*c1*c1*var_fx(1);
+}
+
+Matrix <float, 6, 1>  EKF_RP::fxd()
+{
+    Matrix <float, 6, 1> retval;
+    retval << x(0) + Ts*(u(0) - x(2) + (s1*s2*(u(1) - x(3)))/c2),
+                                      x(1) + Ts*c1*(u(1) - x(3)),
+                                                            x(2),
+                                                            x(3),
+                                      x(4) + Ts*(g*s2 - kv*x(4)),
+                                   x(5) - Ts*(kv*x(5) + c2*g*s1);
+    return retval;
+}
+
+Matrix <float, 2, 1> EKF_RP::gy()
+{
+    Matrix <float, 2, 1> retval;
+    retval << -kv*x(4),
+              -kv*x(5);
+    return retval;
+}
+