altb_pmic / AHRS

AHRS

Dependencies:   Eigen

Dependents:   IndNav_QK3_T265

EKF_RP.cpp@22:495a419e474c, 2019-10-28 (annotated)

Committer:
altb2
Date:
Mon Oct 28 07:52:43 2019 +0000
Revision:
22:495a419e474c
Parent:
21:31e01d3e0143
Child:
23:71996bfe68eb
EKF_RPY and EKF_RP from pmic

Who changed what in which revision?

UserRevisionLine numberNew contents of line
altb2 21:31e01d3e0143 1 #include "EKF_RP.h"
altb2 21:31e01d3e0143 2
altb2 21:31e01d3e0143 3 using namespace std;
altb2 21:31e01d3e0143 4 using namespace Eigen;
altb2 21:31e01d3e0143 5
altb2 21:31e01d3e0143 6 EKF_RP::EKF_RP(float Ts)
altb2 21:31e01d3e0143 7 {
altb2 21:31e01d3e0143 8 this->Ts = Ts;
altb2 21:31e01d3e0143 9 /* [n_gyro; n_b_g; n_v] */
altb2 22:495a419e474c 10 var_fx << 0.1f, 0.1f, 0.002f, 0.002f, 0.002f, 0.002f;
altb2 21:31e01d3e0143 11 /* [n_acc] */
altb2 22:495a419e474c 12 var_gy << 40.0f, 40.0f;
altb2 22:495a419e474c 13 rho = 1.0f;
altb2 21:31e01d3e0143 14 kv = 0.5f; /* k1/m */
altb2 21:31e01d3e0143 15 g = 9.81f;
altb2 21:31e01d3e0143 16 reset();
altb2 21:31e01d3e0143 17 }
altb2 21:31e01d3e0143 18
altb2 21:31e01d3e0143 19 EKF_RP::~EKF_RP() {}
altb2 21:31e01d3e0143 20
altb2 21:31e01d3e0143 21 void EKF_RP::reset()
altb2 21:31e01d3e0143 22 {
altb2 21:31e01d3e0143 23 u.setZero();
altb2 21:31e01d3e0143 24 y.setZero();
altb2 21:31e01d3e0143 25 x.setZero();
altb2 21:31e01d3e0143 26 update_angles();
altb2 21:31e01d3e0143 27 calc_F();
altb2 21:31e01d3e0143 28 calc_H();
altb2 21:31e01d3e0143 29 initialize_Q();
altb2 21:31e01d3e0143 30 initialize_R();
altb2 21:31e01d3e0143 31 P = Q;
altb2 21:31e01d3e0143 32 K.setZero();
altb2 21:31e01d3e0143 33 I.setIdentity();
altb2 22:495a419e474c 34 e.setZero();
altb2 21:31e01d3e0143 35 }
altb2 21:31e01d3e0143 36
altb2 21:31e01d3e0143 37 float EKF_RP::get_est_state(uint8_t i)
altb2 21:31e01d3e0143 38 {
altb2 21:31e01d3e0143 39 /* x = [ang; v; b_g] = [0: phi
altb2 21:31e01d3e0143 40 1: theta
altb2 21:31e01d3e0143 41 2: vx
altb2 21:31e01d3e0143 42 3: vy
altb2 21:31e01d3e0143 43 4: b_gx
altb2 21:31e01d3e0143 44 5: b_gy] */
altb2 21:31e01d3e0143 45 return x(i);
altb2 21:31e01d3e0143 46 }
altb2 21:31e01d3e0143 47
altb2 21:31e01d3e0143 48 void EKF_RP::update(float gyro_x, float gyro_y, float accel_x, float accel_y)
altb2 21:31e01d3e0143 49 {
altb2 21:31e01d3e0143 50 u << gyro_x, gyro_y;
altb2 21:31e01d3e0143 51 y << accel_x, accel_y;
altb2 21:31e01d3e0143 52 update_angles();
altb2 21:31e01d3e0143 53
altb2 21:31e01d3e0143 54 calc_F();
altb2 21:31e01d3e0143 55 // calc_H(); /* H remains constant */
altb2 21:31e01d3e0143 56 calc_Q();
altb2 21:31e01d3e0143 57
altb2 21:31e01d3e0143 58 x = fxd();
altb2 21:31e01d3e0143 59 P = F * P * F.transpose() + Q;
altb2 22:495a419e474c 60 e = y - gy();
altb2 21:31e01d3e0143 61
altb2 22:495a419e474c 62 /* inversion faster 184 mus < 207 mus recursion */
altb2 21:31e01d3e0143 63 K = P * H.transpose() * ( H * P * H.transpose() + R ).inverse();
altb2 22:495a419e474c 64 x = x + K * e;
altb2 22:495a419e474c 65 P = (I - K * H) * P;
altb2 21:31e01d3e0143 66
altb2 22:495a419e474c 67 /* only valid if R is diagonal (uncorrelated noise) */
altb2 22:495a419e474c 68 /*
altb2 22:495a419e474c 69 for(uint8_t i = 0; i < 2; i++) {
altb2 22:495a419e474c 70 K.col(i) = ( P * (H.row(i)).transpose() ) / ( H.row(i) * P * (H.row(i)).transpose() + R(i,i) );
altb2 22:495a419e474c 71 x = x + K.col(i) * e(i);
altb2 22:495a419e474c 72 P = (I - K.col(i)*H.row(i)) * P;
altb2 22:495a419e474c 73 }
altb2 22:495a419e474c 74 */
altb2 21:31e01d3e0143 75 }
altb2 21:31e01d3e0143 76
altb2 21:31e01d3e0143 77 void EKF_RP::update_angles()
altb2 21:31e01d3e0143 78 {
altb2 21:31e01d3e0143 79 s1 = sinf(x(0));
altb2 21:31e01d3e0143 80 c1 = cosf(x(0));
altb2 21:31e01d3e0143 81 s2 = sinf(x(1));
altb2 21:31e01d3e0143 82 c2 = cosf(x(1));
altb2 21:31e01d3e0143 83 }
altb2 21:31e01d3e0143 84
altb2 21:31e01d3e0143 85 void EKF_RP::calc_F()
altb2 21:31e01d3e0143 86 {
altb2 21:31e01d3e0143 87 F << Ts*c1*s2*(u(1) - x(3))/c2 + 1.0f, Ts*s1*(u(1) - x(3))/(c2*c2), -Ts, -Ts*s1*s2/c2, 0.0f, 0.0f,
altb2 21:31e01d3e0143 88 -Ts*s1*(u(1) - x(3)), 1.0f, 0.0f, -Ts*c1, 0.0f, 0.0f,
altb2 21:31e01d3e0143 89 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
altb2 21:31e01d3e0143 90 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
altb2 21:31e01d3e0143 91 0.0f, Ts*c2*g, 0.0f, 0.0f, 1.0f - Ts*kv, 0.0f,
altb2 21:31e01d3e0143 92 -Ts*c1*c2*g, Ts*g*s1*s2, 0.0f, 0.0f, 0.0f, 1.0f - Ts*kv;
altb2 21:31e01d3e0143 93 }
altb2 21:31e01d3e0143 94
altb2 21:31e01d3e0143 95 void EKF_RP::calc_H()
altb2 21:31e01d3e0143 96 {
altb2 21:31e01d3e0143 97 H << 0.0f, 0.0f, 0.0f, 0.0f, -kv, 0.0f,
altb2 21:31e01d3e0143 98 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -kv;
altb2 21:31e01d3e0143 99 }
altb2 21:31e01d3e0143 100
altb2 21:31e01d3e0143 101 void EKF_RP::initialize_R()
altb2 21:31e01d3e0143 102 {
altb2 21:31e01d3e0143 103 R << rho*var_gy(0)/Ts, 0.0f,
altb2 21:31e01d3e0143 104 0.0f, rho*var_gy(1)/Ts;
altb2 21:31e01d3e0143 105 }
altb2 21:31e01d3e0143 106
altb2 21:31e01d3e0143 107 void EKF_RP::initialize_Q()
altb2 21:31e01d3e0143 108 {
altb2 21:31e01d3e0143 109 Q << Ts*(var_fx(0) + s1*s1*s2*s2*var_fx(1)/(c2*c2)), Ts*c1*s1*s2*var_fx(1)/c2, 0.0f, 0.0f, 0.0f, 0.0f,
altb2 21:31e01d3e0143 110 Ts*c1*s1*s2*var_fx(1)/c2, Ts*c1*c1*var_fx(1), 0.0f, 0.0f, 0.0f, 0.0f,
altb2 21:31e01d3e0143 111 0.0f, 0.0f, Ts*var_fx(2), 0.0f, 0.0f, 0.0f,
altb2 21:31e01d3e0143 112 0.0f, 0.0f, 0.0f, Ts*var_fx(3), 0.0f, 0.0f,
altb2 21:31e01d3e0143 113 0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(4), 0.0f,
altb2 21:31e01d3e0143 114 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, Ts*var_fx(5);
altb2 21:31e01d3e0143 115 }
altb2 21:31e01d3e0143 116
altb2 21:31e01d3e0143 117 void EKF_RP::calc_Q()
altb2 21:31e01d3e0143 118 {
altb2 21:31e01d3e0143 119 Q(0,0) = Ts*(var_fx(0) + s1*s1*s2*s2*var_fx(1)/(c2*c2));
altb2 21:31e01d3e0143 120 Q(0,1) = Ts*c1*s1*s2*var_fx(1)/c2;
altb2 21:31e01d3e0143 121 Q(1,0) = Q(0,1);
altb2 21:31e01d3e0143 122 Q(1,1) = Ts*c1*c1*var_fx(1);
altb2 21:31e01d3e0143 123 }
altb2 21:31e01d3e0143 124
altb2 21:31e01d3e0143 125 Matrix <float, 6, 1> EKF_RP::fxd()
altb2 21:31e01d3e0143 126 {
altb2 21:31e01d3e0143 127 Matrix <float, 6, 1> retval;
altb2 21:31e01d3e0143 128 retval << x(0) + Ts*(u(0) - x(2) + (s1*s2*(u(1) - x(3)))/c2),
altb2 21:31e01d3e0143 129 x(1) + Ts*c1*(u(1) - x(3)),
altb2 21:31e01d3e0143 130 x(2),
altb2 21:31e01d3e0143 131 x(3),
altb2 21:31e01d3e0143 132 x(4) + Ts*(g*s2 - kv*x(4)),
altb2 21:31e01d3e0143 133 x(5) - Ts*(kv*x(5) + c2*g*s1);
altb2 21:31e01d3e0143 134 return retval;
altb2 21:31e01d3e0143 135 }
altb2 21:31e01d3e0143 136
altb2 21:31e01d3e0143 137 Matrix <float, 2, 1> EKF_RP::gy()
altb2 21:31e01d3e0143 138 {
altb2 21:31e01d3e0143 139 Matrix <float, 2, 1> retval;
altb2 21:31e01d3e0143 140 retval << -kv*x(4),
altb2 21:31e01d3e0143 141 -kv*x(5);
altb2 21:31e01d3e0143 142 return retval;
altb2 21:31e01d3e0143 143 }
altb2 21:31e01d3e0143 144