diff options
Diffstat (limited to 'src/kernel/ao_microkalman.c')
| -rw-r--r-- | src/kernel/ao_microkalman.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/kernel/ao_microkalman.c b/src/kernel/ao_microkalman.c new file mode 100644 index 00000000..0684ea2b --- /dev/null +++ b/src/kernel/ao_microkalman.c @@ -0,0 +1,74 @@ +/* + * Copyright © 2013 Keith Packard <keithp@keithp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#ifndef AO_FLIGHT_TEST +#include <ao.h> +#endif +#include <ao_micropeak.h> + +#define FIX_BITS 16 + +#define to_fix16(x) ((int16_t) ((x) * 65536.0 + 0.5)) +#define to_fix32(x) ((int32_t) ((x) * 65536.0 + 0.5)) +#define from_fix8(x) ((x) >> 8) +#define from_fix(x) ((x) >> 16) +#define fix8_to_fix16(x) ((x) << 8) +#define fix16_to_fix8(x) ((x) >> 8) + +#include <ao_kalman.h> + +/* Basic time step (96ms) */ +#define AO_MK_STEP to_fix16(0.096) +/* step ** 2 / 2 */ +#define AO_MK_STEP_2_2 to_fix16(0.004608) + +uint32_t ao_k_pa; /* 24.8 fixed point */ +int32_t ao_k_pa_speed; /* 16.16 fixed point */ +int32_t ao_k_pa_accel; /* 16.16 fixed point */ + +uint32_t ao_pa; /* integer portion */ +int16_t ao_pa_speed; /* integer portion */ +int16_t ao_pa_accel; /* integer portion */ + +void +ao_microkalman_init(void) +{ + ao_pa = pa; + ao_k_pa = pa << 8; +} + +void +ao_microkalman_predict(void) +{ + ao_k_pa += fix16_to_fix8((int32_t) ao_pa_speed * AO_MK_STEP + (int32_t) ao_pa_accel * AO_MK_STEP_2_2); + ao_k_pa_speed += (int32_t) ao_pa_accel * AO_MK_STEP; +} + +void +ao_microkalman_correct(void) +{ + int16_t e; /* Height error in Pa */ + + e = pa - from_fix8(ao_k_pa); + + ao_k_pa += fix16_to_fix8((int32_t) e * AO_MK_BARO_K0_10); + ao_k_pa_speed += (int32_t) e * AO_MK_BARO_K1_10; + ao_k_pa_accel += (int32_t) e * AO_MK_BARO_K2_10; + ao_pa = from_fix8(ao_k_pa); + ao_pa_speed = from_fix(ao_k_pa_speed); + ao_pa_accel = from_fix(ao_k_pa_accel); +} |