Chun Feng Huang / ATTITUDE_ESTIMATION_WIPV

Attitude estimation using IMU (3-DoF ver.)

Fork of ATTITUDE_ESTIMATION by LDSC_Robotics_TAs

ATTITUDE_ESTIMATION.cpp@10:166006e89252, 2017-01-04 (annotated)

Committer:
benson516
Date:
Wed Jan 04 10:50:27 2017 +0000
Revision:
10:166006e89252
Parent:
9:84fad91d3587
Child:
11:394a59f3b1f6
Remove the class LPF_vector and use the LPF_vector in FILTER_LIB instead

Who changed what in which revision?

UserRevisionLine numberNew contents of line
benson516 0:8126c86bac2a 1 #include "ATTITUDE_ESTIMATION.h"
benson516 0:8126c86bac2a 2
benson516 10:166006e89252 3 /*
benson516 6:c362ed165c39 4 //=====================LPF ====================//
benson516 6:c362ed165c39 5 LPF_vector::LPF_vector(size_t dimension, float samplingTime, float cutOff_freq_Hz_in)
benson516 6:c362ed165c39 6 {
benson516 6:c362ed165c39 7 n = dimension;
benson516 6:c362ed165c39 8 Ts = samplingTime;
benson516 6:c362ed165c39 9 cutOff_freq_Hz = cutOff_freq_Hz_in;
benson516 6:c362ed165c39 10 alpha_Ts = (2*3.1415926)*cutOff_freq_Hz*Ts;
benson516 6:c362ed165c39 11 One_alpha_Ts = 1.0 - alpha_Ts;
benson516 6:c362ed165c39 12
benson516 6:c362ed165c39 13 zeros.assign(n, 0.0);
benson516 6:c362ed165c39 14
benson516 6:c362ed165c39 15 output = zeros;
benson516 6:c362ed165c39 16
benson516 6:c362ed165c39 17 //
benson516 6:c362ed165c39 18 Flag_Init = false;
benson516 6:c362ed165c39 19 }
benson516 6:c362ed165c39 20
benson516 6:c362ed165c39 21 vector<float> LPF_vector::filter(const vector<float> &input)
benson516 6:c362ed165c39 22 {
benson516 6:c362ed165c39 23 // Initialization
benson516 6:c362ed165c39 24 if (!Flag_Init){
benson516 6:c362ed165c39 25 reset(input);
benson516 6:c362ed165c39 26 Flag_Init = true;
benson516 6:c362ed165c39 27 return output;
benson516 6:c362ed165c39 28 }
benson516 6:c362ed165c39 29
benson516 6:c362ed165c39 30 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 31 // output = One_alpha_Ts*output + alpha_Ts*input;
benson516 6:c362ed165c39 32 output[i] += alpha_Ts*(input[i] - output[i]);
benson516 6:c362ed165c39 33 }
benson516 6:c362ed165c39 34
benson516 6:c362ed165c39 35 return output;
benson516 6:c362ed165c39 36 }
benson516 6:c362ed165c39 37 void LPF_vector::reset(const vector<float> &input)
benson516 6:c362ed165c39 38 {
benson516 6:c362ed165c39 39 // output = (1.0 - alpha_Ts)*output + alpha_Ts*input;
benson516 6:c362ed165c39 40 output = input;
benson516 6:c362ed165c39 41 return;
benson516 6:c362ed165c39 42 }
benson516 10:166006e89252 43 */
benson516 6:c362ed165c39 44
benson516 6:c362ed165c39 45 //-------------------------------------------------------//
benson516 9:84fad91d3587 46 ATTITUDE::ATTITUDE(float alpha_in, float Ts_in):
benson516 6:c362ed165c39 47 alpha(alpha_in),
benson516 6:c362ed165c39 48 Ts(Ts_in),
benson516 8:3882cb4be9d3 49 lpfv_y_acce(3, Ts_in, 10.0), // Input filter for accelerometers
benson516 8:3882cb4be9d3 50 lpfv_y_mag(3, Ts_in, 200.0), // Input filter for magenetometers
benson516 8:3882cb4be9d3 51 lpfv_w(3, Ts_in, 200.0) // Input filter for gyroscope
benson516 0:8126c86bac2a 52 {
benson516 6:c362ed165c39 53 // Dimension
benson516 6:c362ed165c39 54 n = 3;
benson516 6:c362ed165c39 55 //
benson516 6:c362ed165c39 56 init_flag = 0; // Uninitialized
benson516 6:c362ed165c39 57
benson516 6:c362ed165c39 58 // Default: close the gyro-bias estimation
benson516 6:c362ed165c39 59 enable_biasEst = false;
benson516 9:84fad91d3587 60 one_over_gamma = 0.0;
benson516 9:84fad91d3587 61 // Default: close the estimation for magenetic field
benson516 8:3882cb4be9d3 62 enable_magEst = false;
benson516 6:c362ed165c39 63
benson516 6:c362ed165c39 64 // Unit transformation
benson516 6:c362ed165c39 65 pi = 3.1415926;
benson516 6:c362ed165c39 66 deg2rad = pi/180.0;
benson516 6:c362ed165c39 67 rad2deg = 180.0/pi;
benson516 7:6fc812e342e6 68 gravity = 9.81; // m/s^2
benson516 6:c362ed165c39 69
benson516 6:c362ed165c39 70 // The map from "real" coordinate to "here" coordinate
benson516 6:c362ed165c39 71 // eg. accMap_real2here = [3,-1,-2];
benson516 6:c362ed165c39 72 // means: real -> here
benson516 6:c362ed165c39 73 // 1 x z 3
benson516 6:c362ed165c39 74 // 2 y -x -1
benson516 6:c362ed165c39 75 // 3 z -y -2
benson516 6:c362ed165c39 76 // int accmap_temp[] = {3,-1,-2};
benson516 6:c362ed165c39 77 int accmap_temp[] = {-3,1,2}; // Reverse: The direction of accelerometer is defined based on the direction of the acceleration of the sensor, not the g-direction
benson516 6:c362ed165c39 78 // int accmap_temp[] = {1, 2, 3};
benson516 6:c362ed165c39 79 //
benson516 8:3882cb4be9d3 80 int magMap_temp[] = {3,-1, 2}; // real z-axis is in the reverse direction
benson516 6:c362ed165c39 81 int gyroMap_temp[] = {3,-1,-2};
benson516 6:c362ed165c39 82 accMap_real2here.assign(accmap_temp, accmap_temp+n);
benson516 8:3882cb4be9d3 83 magMap_real2here.assign(magMap_temp, magMap_temp+n);
benson516 6:c362ed165c39 84 gyroMap_real2here.assign(gyroMap_temp, gyroMap_temp+n);
benson516 6:c362ed165c39 85
benson516 6:c362ed165c39 86 // zeros
benson516 6:c362ed165c39 87 zeros.assign(n,0.0);
benson516 6:c362ed165c39 88 // unit_nz
benson516 6:c362ed165c39 89 unit_nx = zeros;
benson516 6:c362ed165c39 90 unit_ny = zeros;
benson516 6:c362ed165c39 91 unit_nz = zeros;
benson516 6:c362ed165c39 92 unit_nx[0] = -1; // negative x
benson516 6:c362ed165c39 93 unit_ny[1] = -1; // negative y
benson516 6:c362ed165c39 94 unit_nz[2] = -1; // negative z
benson516 6:c362ed165c39 95
benson516 6:c362ed165c39 96 // States
benson516 8:3882cb4be9d3 97 xg_est = unit_nx; // g is pointing downward
benson516 8:3882cb4be9d3 98 xm_est = Get_VectorScalarMultiply(unit_nz, -1.0); // m is pointing forward
benson516 6:c362ed165c39 99 gyroBias_est = zeros;
benson516 6:c362ed165c39 100 omega = zeros;
benson516 8:3882cb4be9d3 101 //
benson516 8:3882cb4be9d3 102 y_acce = zeros; // Accelerometer outputs
benson516 8:3882cb4be9d3 103 y_mag = zeros; // Magnetometer outputs
benson516 8:3882cb4be9d3 104 //
benson516 8:3882cb4be9d3 105 // w_cross_ys = zeros; // omega X ys
benson516 6:c362ed165c39 106 ys_cross_x_ys = zeros; // ys X (x_est - ys)
benson516 6:c362ed165c39 107
benson516 6:c362ed165c39 108 // Eular angles, in rad/s
benson516 6:c362ed165c39 109 pitch = 0.0;
benson516 6:c362ed165c39 110 roll = 0.0;
benson516 6:c362ed165c39 111 yaw = 0.0;
benson516 6:c362ed165c39 112
benson516 6:c362ed165c39 113
benson516 6:c362ed165c39 114 // Gain matrix
benson516 1:edc7ccfc5562 115 Set_L1_diag(alpha);
benson516 6:c362ed165c39 116
benson516 6:c362ed165c39 117 }
benson516 7:6fc812e342e6 118 // Public methods
benson516 8:3882cb4be9d3 119 void ATTITUDE::Vectors_to_EulerAngle(const vector<float> &vg_in, const vector<float> &vm_in){
benson516 7:6fc812e342e6 120 //
benson516 7:6fc812e342e6 121 // This function should be customized according to the definition of coordinate system
benson516 7:6fc812e342e6 122 //
benson516 6:c362ed165c39 123
benson516 7:6fc812e342e6 124 /*
benson516 7:6fc812e342e6 125 // Here we follow the definition in bicycle paper
benson516 7:6fc812e342e6 126 yaw = 0.0; // phi, yaw
benson516 8:3882cb4be9d3 127 roll = atan2(-vg_in[1],vg_in[0]); // theta, roll
benson516 8:3882cb4be9d3 128 pitch = atan2(cos(roll)*vg_in[2],vg_in[0]); // psi, pitch
benson516 7:6fc812e342e6 129 */
benson516 7:6fc812e342e6 130
benson516 9:84fad91d3587 131 // Eular angle: 1-3-2, zs is pointing forward
benson516 8:3882cb4be9d3 132 // yaw = 0.0; // phi, yaw
benson516 8:3882cb4be9d3 133 pitch = atan2(-vg_in[2],-vg_in[0]); // psi, pitch
benson516 7:6fc812e342e6 134 if (abs(pitch) < 0.7854){ // pi/4
benson516 8:3882cb4be9d3 135 roll = atan2(cos(pitch)*vg_in[1],-vg_in[0]); // theta, roll
benson516 7:6fc812e342e6 136 }else{
benson516 7:6fc812e342e6 137 if (pitch >= 0.0)
benson516 8:3882cb4be9d3 138 roll = atan2(sin(pitch)*vg_in[1],-vg_in[2]); // theta, roll
benson516 7:6fc812e342e6 139 else
benson516 8:3882cb4be9d3 140 roll = atan2(-sin(pitch)*vg_in[1],vg_in[2]); // theta, roll
benson516 7:6fc812e342e6 141 }
benson516 7:6fc812e342e6 142
benson516 8:3882cb4be9d3 143 // Calculate the yaw angle
benson516 8:3882cb4be9d3 144 if (enable_magEst){
benson516 8:3882cb4be9d3 145 float num = vm_in[1]*cos(pitch);
benson516 8:3882cb4be9d3 146 float den = (vm_in[2]*cos(roll) - vm_in[1]*sin(pitch)*sin(roll));
benson516 8:3882cb4be9d3 147 yaw = atan2(num, den);
benson516 8:3882cb4be9d3 148 }else{
benson516 8:3882cb4be9d3 149 yaw = 0.0; // phi, yaw
benson516 8:3882cb4be9d3 150 }
benson516 7:6fc812e342e6 151
benson516 7:6fc812e342e6 152 }
benson516 7:6fc812e342e6 153 // Setting parameters
benson516 7:6fc812e342e6 154 // Set L1, the diagonal matrix
benson516 7:6fc812e342e6 155 void ATTITUDE::Set_L1_diag(float alpha_in) // set diagnal element of gain matrix
benson516 7:6fc812e342e6 156 {
benson516 7:6fc812e342e6 157 alpha = alpha_in;
benson516 7:6fc812e342e6 158 L1_diag.assign(n,alpha_in);
benson516 7:6fc812e342e6 159 }
benson516 9:84fad91d3587 160 void ATTITUDE::enable_gyroBiasEst(float gamma_in){ // Enable the gyro-bias estimation
benson516 9:84fad91d3587 161 enable_biasEst = true;
benson516 9:84fad91d3587 162 one_over_gamma = 1/gamma_in;
benson516 9:84fad91d3587 163 }
benson516 7:6fc812e342e6 164 //
benson516 8:3882cb4be9d3 165 void ATTITUDE::Init(void) // Let x_est = ys
benson516 7:6fc812e342e6 166 {
benson516 8:3882cb4be9d3 167 // y_acce = y_in;
benson516 8:3882cb4be9d3 168 // Normolization(xg_est,y_in); // xg_est be set as normalized y_in
benson516 8:3882cb4be9d3 169 xg_est = y_acce;
benson516 8:3882cb4be9d3 170 xm_est = y_mag;
benson516 7:6fc812e342e6 171 ++init_flag;
benson516 7:6fc812e342e6 172 }
benson516 8:3882cb4be9d3 173 void ATTITUDE::iterateOnce(const vector<float> &y_acce_in, const vector<float> &omega_in) // Main alogorithm
benson516 7:6fc812e342e6 174 {
benson516 8:3882cb4be9d3 175 enable_magEst = false; // no magenetometers input
benson516 8:3882cb4be9d3 176 // Input mapping
benson516 8:3882cb4be9d3 177 InputMapping(y_acce, y_acce_in, accMap_real2here);
benson516 8:3882cb4be9d3 178 // InputMapping(y_mag, y_mag_in, magMap_real2here);
benson516 7:6fc812e342e6 179 InputMapping(omega, omega_in, gyroMap_real2here);
benson516 7:6fc812e342e6 180
benson516 7:6fc812e342e6 181 // Input filter
benson516 8:3882cb4be9d3 182 y_acce = lpfv_y_acce.filter(y_acce);
benson516 8:3882cb4be9d3 183 // y_mag = lpfv_y_mag.filter(y_mag);
benson516 7:6fc812e342e6 184 // omega = lpfv_w.filter(omega);
benson516 7:6fc812e342e6 185
benson516 7:6fc812e342e6 186 // gyro-bias estimation
benson516 7:6fc812e342e6 187 if (enable_biasEst){
benson516 8:3882cb4be9d3 188 omega = Get_VectorPlus(omega, gyroBias_est, true); // minus, omega - gyroBias_est
benson516 7:6fc812e342e6 189 }
benson516 7:6fc812e342e6 190
benson516 7:6fc812e342e6 191 //
benson516 7:6fc812e342e6 192 if(init_flag < 3){
benson516 8:3882cb4be9d3 193 Init();
benson516 7:6fc812e342e6 194 }
benson516 7:6fc812e342e6 195 else{
benson516 8:3882cb4be9d3 196 // Estimation kernel process
benson516 8:3882cb4be9d3 197 EstimationKernel(xg_est, y_acce, omega);
benson516 8:3882cb4be9d3 198 // EstimationKernel(xm_est, y_mag, omega);
benson516 7:6fc812e342e6 199
benson516 7:6fc812e342e6 200 // gyro-bias estimation
benson516 7:6fc812e342e6 201 if (enable_biasEst){
benson516 7:6fc812e342e6 202 updateGyroBiasEst();
benson516 7:6fc812e342e6 203 }
benson516 7:6fc812e342e6 204 }
benson516 7:6fc812e342e6 205 //
benson516 8:3882cb4be9d3 206 Vectors_to_EulerAngle(xg_est,xm_est);
benson516 8:3882cb4be9d3 207 }
benson516 8:3882cb4be9d3 208 void ATTITUDE::iterateOnce(const vector<float> &y_acce_in, const vector<float> &y_mag_in, const vector<float> &omega_in) // Main alogorithm
benson516 8:3882cb4be9d3 209 {
benson516 8:3882cb4be9d3 210 enable_magEst = true; // with magenetometers input
benson516 8:3882cb4be9d3 211 // Input mapping
benson516 8:3882cb4be9d3 212 InputMapping(y_acce, y_acce_in, accMap_real2here);
benson516 8:3882cb4be9d3 213 InputMapping(y_mag, y_mag_in, magMap_real2here);
benson516 8:3882cb4be9d3 214 InputMapping(omega, omega_in, gyroMap_real2here);
benson516 8:3882cb4be9d3 215
benson516 8:3882cb4be9d3 216 // Input filter
benson516 8:3882cb4be9d3 217 y_acce = lpfv_y_acce.filter(y_acce);
benson516 8:3882cb4be9d3 218 // y_mag = lpfv_y_mag.filter(y_mag);
benson516 8:3882cb4be9d3 219 // omega = lpfv_w.filter(omega);
benson516 8:3882cb4be9d3 220
benson516 8:3882cb4be9d3 221 // gyro-bias estimation
benson516 8:3882cb4be9d3 222 if (enable_biasEst){
benson516 8:3882cb4be9d3 223 omega = Get_VectorPlus(omega, gyroBias_est, true); // minus, omega - gyroBias_est
benson516 8:3882cb4be9d3 224 }
benson516 8:3882cb4be9d3 225
benson516 8:3882cb4be9d3 226 //
benson516 8:3882cb4be9d3 227 if(init_flag < 3){
benson516 8:3882cb4be9d3 228 Init();
benson516 8:3882cb4be9d3 229 }
benson516 8:3882cb4be9d3 230 else{
benson516 8:3882cb4be9d3 231 // Estimation kernel process
benson516 8:3882cb4be9d3 232 EstimationKernel(xg_est, y_acce, omega);
benson516 8:3882cb4be9d3 233 EstimationKernel(xm_est, y_mag, omega);
benson516 8:3882cb4be9d3 234
benson516 8:3882cb4be9d3 235 // gyro-bias estimation
benson516 8:3882cb4be9d3 236 if (enable_biasEst){
benson516 8:3882cb4be9d3 237 updateGyroBiasEst();
benson516 8:3882cb4be9d3 238 }
benson516 8:3882cb4be9d3 239 }
benson516 8:3882cb4be9d3 240 //
benson516 8:3882cb4be9d3 241 Vectors_to_EulerAngle(xg_est,xm_est);
benson516 7:6fc812e342e6 242 }
benson516 7:6fc812e342e6 243 // transform the x_est into "real" coordinate
benson516 7:6fc812e342e6 244 void ATTITUDE::getEstimation_realCoordinate(vector<float> &V_out){
benson516 8:3882cb4be9d3 245 OutputMapping(V_out,xg_est,accMap_real2here);
benson516 7:6fc812e342e6 246 }
benson516 7:6fc812e342e6 247 // Get Eular angles
benson516 7:6fc812e342e6 248 float ATTITUDE::pitch_deg(void){
benson516 7:6fc812e342e6 249 return (rad2deg*pitch);
benson516 7:6fc812e342e6 250 }
benson516 7:6fc812e342e6 251 float ATTITUDE::roll_deg(void){
benson516 7:6fc812e342e6 252 return (rad2deg*roll);
benson516 7:6fc812e342e6 253 }
benson516 7:6fc812e342e6 254 float ATTITUDE::yaw_deg(void){
benson516 7:6fc812e342e6 255 return (rad2deg*yaw);
benson516 7:6fc812e342e6 256 }
benson516 7:6fc812e342e6 257
benson516 7:6fc812e342e6 258 // Private methods
benson516 7:6fc812e342e6 259 ////////////////////////////////////
benson516 7:6fc812e342e6 260 // Input/output coordinate transformations within the different definitions between the "real" one and the "here" one
benson516 6:c362ed165c39 261 // real -> here
benson516 6:c362ed165c39 262 void ATTITUDE::InputMapping(vector<float> &v_hereDef, const vector<float> &v_realDef, const vector<int> &map_real2here){
benson516 6:c362ed165c39 263 // The map from "real" coordinate to "here" coordinate
benson516 6:c362ed165c39 264 // eg. accMap_real2here = [3,-1,-2];
benson516 6:c362ed165c39 265 // means: real -> here
benson516 6:c362ed165c39 266 // 1 x z 3
benson516 6:c362ed165c39 267 // 2 y -x -1
benson516 6:c362ed165c39 268 // 3 z -y -2
benson516 6:c362ed165c39 269 // vector<int> accMap_real2here = {3,-1,-2};
benson516 6:c362ed165c39 270 // vector<int> gyroMap_real2here = {3,-1,-2};
benson516 6:c362ed165c39 271
benson516 6:c362ed165c39 272 // Iterate through "real" coordinates
benson516 6:c362ed165c39 273 int idx_here = 1;
benson516 6:c362ed165c39 274 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 275 idx_here = map_real2here[i];
benson516 6:c362ed165c39 276 if (idx_here > 0){
benson516 6:c362ed165c39 277 v_hereDef[idx_here-1] = v_realDef[i];
benson516 6:c362ed165c39 278 }else{
benson516 6:c362ed165c39 279 v_hereDef[-idx_here-1] = -1*v_realDef[i];
benson516 6:c362ed165c39 280 }
benson516 6:c362ed165c39 281 }
benson516 0:8126c86bac2a 282 }
benson516 6:c362ed165c39 283 // here -> real
benson516 6:c362ed165c39 284 void ATTITUDE::OutputMapping(vector<float> &v_realDef, const vector<float> &v_hereDef, const vector<int> &map_real2here){
benson516 6:c362ed165c39 285 // This is the inverse mapping of the InputMapping
benson516 6:c362ed165c39 286
benson516 6:c362ed165c39 287 // The map from "real" coordinate to "here" coordinate
benson516 6:c362ed165c39 288 // eg. accMap_real2here = [3,-1,-2];
benson516 6:c362ed165c39 289 // means: real -> here
benson516 6:c362ed165c39 290 // 1 x z 3
benson516 6:c362ed165c39 291 // 2 y -x -1
benson516 6:c362ed165c39 292 // 3 z -y -2
benson516 6:c362ed165c39 293 // vector<int> accMap_real2here = {3,-1,-2};
benson516 6:c362ed165c39 294 // vector<int> gyroMap_real2here = {3,-1,-2};
benson516 6:c362ed165c39 295
benson516 6:c362ed165c39 296 // Iterate through "real" coordinates
benson516 6:c362ed165c39 297 int idx_here = 1;
benson516 6:c362ed165c39 298 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 299 idx_here = map_real2here[i];
benson516 6:c362ed165c39 300 if (idx_here > 0){
benson516 6:c362ed165c39 301 v_realDef[i] = v_hereDef[idx_here-1];
benson516 6:c362ed165c39 302 }else{
benson516 6:c362ed165c39 303 v_realDef[i] = -1*v_hereDef[-idx_here-1];
benson516 6:c362ed165c39 304 }
benson516 6:c362ed165c39 305 }
benson516 6:c362ed165c39 306 }
benson516 7:6fc812e342e6 307 // The kernel of the estimation process
benson516 7:6fc812e342e6 308 ////////////////////////////////////////
benson516 7:6fc812e342e6 309 void ATTITUDE::EstimationKernel(vector<float> &_x_est_, const vector<float> &_ys_, const vector<float> &_omega_){
benson516 7:6fc812e342e6 310 static vector<float> _w_cross_ys_;
benson516 7:6fc812e342e6 311 Get_CrossProduct3(_w_cross_ys_, _omega_, _ys_);
benson516 8:3882cb4be9d3 312 for(size_t i = 0; i < n; ++i){
benson516 7:6fc812e342e6 313 // x_est_plus[i] = x_est[i] + Ts*( L1_diag[i]*(ys[i] - x_est[i]) - w_cross_ys[i]);
benson516 7:6fc812e342e6 314 _x_est_[i] += Ts*( L1_diag[i]*(_ys_[i] - _x_est_[i]) - _w_cross_ys_[i]);
benson516 6:c362ed165c39 315 }
benson516 6:c362ed165c39 316
benson516 7:6fc812e342e6 317 }
benson516 7:6fc812e342e6 318 void ATTITUDE::updateGyroBiasEst(void){ // Update the gyro bias estimation
benson516 7:6fc812e342e6 319 if (one_over_gamma == 0.0){
benson516 7:6fc812e342e6 320 return;
benson516 7:6fc812e342e6 321 }
benson516 7:6fc812e342e6 322 //
benson516 8:3882cb4be9d3 323 Get_CrossProduct3(ys_cross_x_ys, y_acce, Get_VectorPlus(xg_est,y_acce,true));
benson516 7:6fc812e342e6 324 //
benson516 7:6fc812e342e6 325 gyroBias_est = Get_VectorPlus(gyroBias_est, Get_VectorScalarMultiply(ys_cross_x_ys, (one_over_gamma)), true);
benson516 7:6fc812e342e6 326 }
benson516 6:c362ed165c39 327
benson516 7:6fc812e342e6 328 //////////////////////////////////////// end The kernal of the estimation process
benson516 7:6fc812e342e6 329
benson516 7:6fc812e342e6 330 // Utilities
benson516 7:6fc812e342e6 331 // vector operation
benson516 6:c362ed165c39 332 void ATTITUDE::Get_CrossProduct3(vector<float> &v_c, const vector<float> &v_a, const vector<float> &v_b) // v_a X v_b
benson516 1:edc7ccfc5562 333 {
benson516 7:6fc812e342e6 334 // Check the size
benson516 7:6fc812e342e6 335 if (v_c.size() != n){
benson516 7:6fc812e342e6 336 v_c.resize(n);
benson516 7:6fc812e342e6 337 }
benson516 1:edc7ccfc5562 338 v_c[0] = (-v_a[2]*v_b[1]) + v_a[1]*v_b[2];
benson516 1:edc7ccfc5562 339 v_c[1] = v_a[2]*v_b[0] - v_a[0]*v_b[2];
benson516 6:c362ed165c39 340 v_c[2] = (-v_a[1]*v_b[0]) + v_a[0]*v_b[1];
benson516 1:edc7ccfc5562 341 }
benson516 6:c362ed165c39 342 vector<float> ATTITUDE::Get_VectorPlus(const vector<float> &v_a, const vector<float> &v_b, bool is_minus) // v_a + (or -) v_b
benson516 6:c362ed165c39 343 {
benson516 6:c362ed165c39 344 static vector<float> v_c(n);
benson516 6:c362ed165c39 345 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 346 if (is_minus){
benson516 6:c362ed165c39 347 v_c[i] = v_a[i] - v_b[i];
benson516 6:c362ed165c39 348 }else{
benson516 6:c362ed165c39 349 v_c[i] = v_a[i] + v_b[i];
benson516 6:c362ed165c39 350 }
benson516 6:c362ed165c39 351 }
benson516 6:c362ed165c39 352 return v_c;
benson516 6:c362ed165c39 353 }
benson516 6:c362ed165c39 354 vector<float> ATTITUDE::Get_VectorScalarMultiply(const vector<float> &v_a, float scale) // scale*v_a
benson516 6:c362ed165c39 355 {
benson516 6:c362ed165c39 356 static vector<float> v_c(n);
benson516 6:c362ed165c39 357 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 358 v_c[i] = scale*v_a[i];
benson516 6:c362ed165c39 359
benson516 6:c362ed165c39 360 }
benson516 6:c362ed165c39 361 return v_c;
benson516 6:c362ed165c39 362 }
benson516 6:c362ed165c39 363 float ATTITUDE::Get_Vector3Norm(const vector<float> &v_in)
benson516 1:edc7ccfc5562 364 {
benson516 1:edc7ccfc5562 365 float temp = 0.0;
benson516 6:c362ed165c39 366
benson516 6:c362ed165c39 367 for (size_t i = 0; i < n; ++i)
benson516 1:edc7ccfc5562 368 temp += v_in[i]*v_in[i];
benson516 6:c362ed165c39 369 return sqrt(temp); // <- Should check if this function is available (?)
benson516 1:edc7ccfc5562 370 }
benson516 6:c362ed165c39 371 void ATTITUDE::Normolization(vector<float> &V_out, const vector<float> &V_in){
benson516 6:c362ed165c39 372 float norm = Get_Vector3Norm(V_in);
benson516 6:c362ed165c39 373 for (size_t i = 0; i < n; ++i){
benson516 6:c362ed165c39 374 V_out[i] = V_in[i]/norm;
benson516 6:c362ed165c39 375 }
benson516 6:c362ed165c39 376 }