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   1 /*
   2  * Copyright © 2011 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #ifndef AO_FLIGHT_TEST
  20 #include "ao.h"
  21 #include "ao_flight.h"
  22 #endif
  23
  24 #include "ao_sample.h"
  25 #include "ao_kalman.h"
  26
  27 static __pdata ao_k_t           ao_k_height;
  28 static __pdata ao_k_t           ao_k_speed;
  29 static __pdata ao_k_t           ao_k_accel;
  30
  31 #define AO_K_STEP_100           to_fix_v(0.01)
  32 #define AO_K_STEP_2_2_100       to_fix_v(0.00005)
  33
  34 #define AO_K_STEP_10            to_fix_v(0.1)
  35 #define AO_K_STEP_2_2_10        to_fix_v(0.005)
  36
  37 #define AO_K_STEP_1             to_fix_v(1)
  38 #define AO_K_STEP_2_2_1         to_fix_v(0.5)
  39
  40 __pdata ao_v_t                  ao_height;
  41 __pdata ao_v_t                  ao_speed;
  42 __pdata ao_v_t                  ao_accel;
  43 __xdata ao_v_t                  ao_max_height;
  44 static __pdata ao_k_t           ao_avg_height_scaled;
  45 __xdata ao_v_t                  ao_avg_height;
  46
  47 __pdata ao_v_t                  ao_error_h;
  48 #if !HAS_ACCEL || AO_FLIGHT_TEST
  49 #define AO_ERROR_H_SQ_AVG       1
  50 #endif
  51
  52 #if AO_ERROR_H_SQ_AVG
  53 __pdata ao_v_t                  ao_error_h_sq_avg;
  54 #endif
  55
  56 #if HAS_ACCEL
  57 __pdata ao_v_t                  ao_error_a;
  58 #endif
  59
  60 static void
  61 ao_kalman_predict(void)
  62 {
  63 #ifdef AO_FLIGHT_TEST
  64         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 50) {
  65                 ao_k_height += ((ao_k_t) ao_speed * AO_K_STEP_1 +
  66                                 (ao_k_t) ao_accel * AO_K_STEP_2_2_1) >> 4;
  67                 ao_k_speed += (ao_k_t) ao_accel * AO_K_STEP_1;
  68
  69                 return;
  70         }
  71         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 5) {
  72                 ao_k_height += ((ao_k_t) ao_speed * AO_K_STEP_10 +
  73                                 (ao_k_t) ao_accel * AO_K_STEP_2_2_10) >> 4;
  74                 ao_k_speed += (ao_k_t) ao_accel * AO_K_STEP_10;
  75
  76                 return;
  77         }
  78         if (ao_flight_debug) {
  79                 printf ("predict speed %g + (%g * %g) = %g\n",
  80                         ao_k_speed / (65536.0 * 16.0), ao_accel / 16.0, AO_K_STEP_100 / 65536.0,
  81                         (ao_k_speed + (ao_k_t) ao_accel * AO_K_STEP_100) / (65536.0 * 16.0));
  82         }
  83 #endif
  84         ao_k_height += ((ao_k_t) ao_speed * AO_K_STEP_100 +
  85                         (ao_k_t) ao_accel * AO_K_STEP_2_2_100) >> 4;
  86         ao_k_speed += (ao_k_t) ao_accel * AO_K_STEP_100;
  87 }
  88
  89 static void
  90 ao_kalman_err_height(void)
  91 {
  92 #if AO_ERROR_H_SQ_AVG
  93         ao_v_t  e;
  94 #endif
  95         ao_v_t height_distrust;
  96 #if HAS_ACCEL
  97         ao_v_t  speed_distrust;
  98 #endif
  99
 100         ao_error_h = ao_sample_height - (ao_v_t) (ao_k_height >> 16);
 101
 102 #if AO_ERROR_H_SQ_AVG
 103         e = ao_error_h;
 104         if (e < 0)
 105                 e = -e;
 106         if (e > 127)
 107                 e = 127;
 108         ao_error_h_sq_avg -= ao_error_h_sq_avg >> 4;
 109         ao_error_h_sq_avg += (e * e) >> 4;
 110 #endif
 111
 112         if (ao_flight_state >= ao_flight_drogue)
 113                 return;
 114         height_distrust = ao_sample_alt - AO_MAX_BARO_HEIGHT;
 115 #if HAS_ACCEL
 116         /* speed is stored * 16, but we need to ramp between 248 and 328, so
 117          * we want to multiply by 2. The result is a shift by 3.
 118          */
 119         speed_distrust = (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) >> (4 - 1);
 120         if (speed_distrust > AO_MAX_SPEED_DISTRUST)
 121                 speed_distrust = AO_MAX_SPEED_DISTRUST;
 122         if (speed_distrust > height_distrust)
 123                 height_distrust = speed_distrust;
 124 #endif
 125         if (height_distrust > 0) {
 126 #ifdef AO_FLIGHT_TEST
 127                 int     old_ao_error_h = ao_error_h;
 128 #endif
 129                 if (height_distrust > 0x100)
 130                         height_distrust = 0x100;
 131                 ao_error_h = (ao_v_t) (((ao_k_t) ao_error_h * (0x100 - height_distrust)) >> 8);
 132 #ifdef AO_FLIGHT_TEST
 133                 if (ao_flight_debug) {
 134                         printf("over height %g over speed %g distrust: %g height: error %d -> %d\n",
 135                                (double) (ao_sample_alt - AO_MAX_BARO_HEIGHT),
 136                                (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) / 16.0,
 137                                height_distrust / 256.0,
 138                                old_ao_error_h, ao_error_h);
 139                 }
 140 #endif
 141         }
 142 }
 143
 144 static void
 145 ao_kalman_correct_baro(void)
 146 {
 147         ao_kalman_err_height();
 148 #ifdef AO_FLIGHT_TEST
 149         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 50) {
 150                 ao_k_height += (ao_k_t) AO_BARO_K0_1 * ao_error_h;
 151                 ao_k_speed  += (ao_k_t) AO_BARO_K1_1 * ao_error_h;
 152                 ao_k_accel  += (ao_k_t) AO_BARO_K2_1 * ao_error_h;
 153                 return;
 154         }
 155         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 5) {
 156                 ao_k_height += (ao_k_t) AO_BARO_K0_10 * ao_error_h;
 157                 ao_k_speed  += (ao_k_t) AO_BARO_K1_10 * ao_error_h;
 158                 ao_k_accel  += (ao_k_t) AO_BARO_K2_10 * ao_error_h;
 159                 return;
 160         }
 161 #endif
 162         ao_k_height += (ao_k_t) AO_BARO_K0_100 * ao_error_h;
 163         ao_k_speed  += (ao_k_t) AO_BARO_K1_100 * ao_error_h;
 164         ao_k_accel  += (ao_k_t) AO_BARO_K2_100 * ao_error_h;
 165 }
 166
 167 #if HAS_ACCEL
 168
 169 static void
 170 ao_kalman_err_accel(void)
 171 {
 172         ao_k_t  accel;
 173
 174         accel = (ao_config.accel_plus_g - ao_sample_accel) * ao_accel_scale;
 175
 176         /* Can't use ao_accel here as it is the pre-prediction value still */
 177         ao_error_a = (accel - ao_k_accel) >> 16;
 178 }
 179
 180 #ifndef FORCE_ACCEL
 181 static void
 182 ao_kalman_correct_both(void)
 183 {
 184         ao_kalman_err_height();
 185         ao_kalman_err_accel();
 186
 187 #ifdef AO_FLIGHT_TEST
 188         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 50) {
 189                 if (ao_flight_debug) {
 190                         printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
 191                                 ao_k_speed / (65536.0 * 16.0),
 192                                 (double) ao_error_h, AO_BOTH_K10_1 / 65536.0,
 193                                 (double) ao_error_a, AO_BOTH_K11_1 / 65536.0,
 194                                 (ao_k_speed +
 195                                  (ao_k_t) AO_BOTH_K10_1 * ao_error_h +
 196                                  (ao_k_t) AO_BOTH_K11_1 * ao_error_a) / (65536.0 * 16.0));
 197                 }
 198                 ao_k_height +=
 199                         (ao_k_t) AO_BOTH_K00_1 * ao_error_h +
 200                         (ao_k_t) AO_BOTH_K01_1 * ao_error_a;
 201                 ao_k_speed +=
 202                         (ao_k_t) AO_BOTH_K10_1 * ao_error_h +
 203                         (ao_k_t) AO_BOTH_K11_1 * ao_error_a;
 204                 ao_k_accel +=
 205                         (ao_k_t) AO_BOTH_K20_1 * ao_error_h +
 206                         (ao_k_t) AO_BOTH_K21_1 * ao_error_a;
 207                 return;
 208         }
 209         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 5) {
 210                 if (ao_flight_debug) {
 211                         printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
 212                                 ao_k_speed / (65536.0 * 16.0),
 213                                 (double) ao_error_h, AO_BOTH_K10_10 / 65536.0,
 214                                 (double) ao_error_a, AO_BOTH_K11_10 / 65536.0,
 215                                 (ao_k_speed +
 216                                  (ao_k_t) AO_BOTH_K10_10 * ao_error_h +
 217                                  (ao_k_t) AO_BOTH_K11_10 * ao_error_a) / (65536.0 * 16.0));
 218                 }
 219                 ao_k_height +=
 220                         (ao_k_t) AO_BOTH_K00_10 * ao_error_h +
 221                         (ao_k_t) AO_BOTH_K01_10 * ao_error_a;
 222                 ao_k_speed +=
 223                         (ao_k_t) AO_BOTH_K10_10 * ao_error_h +
 224                         (ao_k_t) AO_BOTH_K11_10 * ao_error_a;
 225                 ao_k_accel +=
 226                         (ao_k_t) AO_BOTH_K20_10 * ao_error_h +
 227                         (ao_k_t) AO_BOTH_K21_10 * ao_error_a;
 228                 return;
 229         }
 230         if (ao_flight_debug) {
 231                 printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
 232                         ao_k_speed / (65536.0 * 16.0),
 233                         (double) ao_error_h, AO_BOTH_K10_100 / 65536.0,
 234                         (double) ao_error_a, AO_BOTH_K11_100 / 65536.0,
 235                         (ao_k_speed +
 236                          (ao_k_t) AO_BOTH_K10_100 * ao_error_h +
 237                          (ao_k_t) AO_BOTH_K11_100 * ao_error_a) / (65536.0 * 16.0));
 238         }
 239 #endif
 240         ao_k_height +=
 241                 (ao_k_t) AO_BOTH_K00_100 * ao_error_h +
 242                 (ao_k_t) AO_BOTH_K01_100 * ao_error_a;
 243         ao_k_speed +=
 244                 (ao_k_t) AO_BOTH_K10_100 * ao_error_h +
 245                 (ao_k_t) AO_BOTH_K11_100 * ao_error_a;
 246         ao_k_accel +=
 247                 (ao_k_t) AO_BOTH_K20_100 * ao_error_h +
 248                 (ao_k_t) AO_BOTH_K21_100 * ao_error_a;
 249 }
 250
 251 #else
 252
 253 static void
 254 ao_kalman_correct_accel(void)
 255 {
 256         ao_kalman_err_accel();
 257
 258         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 5) {
 259                 ao_k_height +=(ao_k_t) AO_ACCEL_K0_10 * ao_error_a;
 260                 ao_k_speed  += (ao_k_t) AO_ACCEL_K1_10 * ao_error_a;
 261                 ao_k_accel  += (ao_k_t) AO_ACCEL_K2_10 * ao_error_a;
 262                 return;
 263         }
 264         ao_k_height += (ao_k_t) AO_ACCEL_K0_100 * ao_error_a;
 265         ao_k_speed  += (ao_k_t) AO_ACCEL_K1_100 * ao_error_a;
 266         ao_k_accel  += (ao_k_t) AO_ACCEL_K2_100 * ao_error_a;
 267 }
 268
 269 #endif /* else FORCE_ACCEL */
 270 #endif /* HAS_ACCEL */
 271
 272 void
 273 ao_kalman(void)
 274 {
 275         ao_kalman_predict();
 276 #if HAS_ACCEL
 277         if (ao_flight_state <= ao_flight_coast) {
 278 #ifdef FORCE_ACCEL
 279                 ao_kalman_correct_accel();
 280 #else
 281                 ao_kalman_correct_both();
 282 #endif
 283         } else
 284 #endif
 285                 ao_kalman_correct_baro();
 286         ao_height = from_fix(ao_k_height);
 287         ao_speed = from_fix(ao_k_speed);
 288         ao_accel = from_fix(ao_k_accel);
 289         if (ao_height > ao_max_height)
 290                 ao_max_height = ao_height;
 291         ao_avg_height_scaled = ao_avg_height_scaled - ao_avg_height + ao_sample_height;
 292 #ifdef AO_FLIGHT_TEST
 293         if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 50)
 294                 ao_avg_height = (ao_avg_height_scaled + 1) >> 1;
 295         else if ((int16_t) (ao_sample_tick - ao_sample_prev_tick) > 5)
 296                 ao_avg_height = (ao_avg_height_scaled + 7) >> 4;
 297         else
 298 #endif
 299                 ao_avg_height = (ao_avg_height_scaled + 63) >> 7;
 300 }