ins_alt_float.c

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/*
 * Copyright (C) 2004-2012 The Paparazzi Team
 *
 * This file is part of paparazzi.
 *
 * paparazzi 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; either version 2, or (at your option)
 * any later version.
 *
 * paparazzi 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 paparazzi; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */
 
#include "modules/ins/ins_alt_float.h"
 
#include "modules/core/abi.h"
#include "state.h"
 
#include <inttypes.h>
#include <math.h>
 
#include "state.h"
#include "mcu_periph/sys_time.h"
#include "modules/gps/gps.h"
#include "firmwares/fixedwing/nav.h"
 
#include "generated/airframe.h"
#include "generated/modules.h"
 
#ifdef DEBUG_ALT_KALMAN
#include "mcu_periph/uart.h"
#include "modules/datalink/downlink.h"
#endif
 
#ifndef USE_INS_NAV_INIT
#define USE_INS_NAV_INIT TRUE
PRINT_CONFIG_MSG("USE_INS_NAV_INIT defaulting to TRUE")
#endif
 
struct InsAltFloat ins_altf;
 
#if USE_BAROMETER
#include "modules/sensors/baro.h"
#include "math/pprz_isa.h"
 
PRINT_CONFIG_MSG("USE_BAROMETER is TRUE: Using baro for altitude estimation.")
 
// Baro event on ABI
#ifndef INS_ALT_BARO_ID
#if USE_BARO_BOARD
#define INS_ALT_BARO_ID BARO_BOARD_SENDER_ID
#else
#define INS_ALT_BARO_ID ABI_BROADCAST
#endif
#endif
PRINT_CONFIG_VAR(INS_ALT_BARO_ID)
 
abi_event baro_ev;
static void baro_cb(uint8_t sender_id, uint32_t stamp, float pressure);
#endif /* USE_BAROMETER */
 
#ifndef INS_ALT_GPS_ID
#define INS_ALT_GPS_ID GPS_MULTI_ID
#endif
PRINT_CONFIG_VAR(INS_ALT_GPS_ID)
static abi_event gps_ev;
static void gps_cb(uint8_t sender_id, uint32_t stamp, struct GpsState *gps_s);
 
#ifndef INS_ALT_IMU_ID
#define INS_ALT_IMU_ID ABI_BROADCAST
#endif
static abi_event accel_ev;
static void accel_cb(uint8_t sender_id, uint32_t stamp, struct Int32Vect3 *accel);
 
static void alt_kalman_reset(void);
static void alt_kalman_init(void);
static void alt_kalman(float z_meas, float dt);
 
void ins_alt_float_update_gps(struct GpsState *gps_s);
 
void ins_alt_float_init(void)
{
#if USE_INS_NAV_INIT
  struct UtmCoor_f utm0 = { nav_utm_north0, nav_utm_east0, ground_alt, nav_utm_zone0 };
  stateSetLocalUtmOrigin_f(&utm0);
  ins_altf.origin_initialized = true;
 
  stateSetPositionUtm_f(&utm0);
#else
  ins_altf.origin_initialized = false;
#endif
 
  alt_kalman_init();
 
#if USE_BAROMETER
  ins_altf.qfe = 0.0f;
  ins_altf.baro_initialized = false;
  ins_altf.baro_alt = 0.0f;
#endif
  ins_altf.reset_alt_ref = false;
 
  // why do we have this here?
  alt_kalman(0.0f, 0.1);
 
#if USE_BAROMETER
  // Bind to BARO_ABS message
  AbiBindMsgBARO_ABS(INS_ALT_BARO_ID, &baro_ev, baro_cb);
#endif
  AbiBindMsgGPS(INS_ALT_GPS_ID, &gps_ev, gps_cb);
  AbiBindMsgIMU_ACCEL(INS_ALT_IMU_ID, &accel_ev, accel_cb);
}
 
void ins_reset_local_origin(void)
{
  // get utm pos
  struct UtmCoor_f utm = utm_float_from_gps(&gps, 0);
 
  // reset state UTM ref
  stateSetLocalUtmOrigin_f(&utm);
 
  ins_altf.origin_initialized = true;
 
  // reset filter flag
  ins_altf.reset_alt_ref = true;
}
 
void ins_reset_altitude_ref(void)
{
  struct UtmCoor_f utm = state.utm_origin_f;
  // ground_alt
  utm.alt = gps.hmsl / 1000.0f;
  // reset state UTM ref
  stateSetLocalUtmOrigin_f(&utm);
  // reset filter flag
  ins_altf.reset_alt_ref = true;
}
 
#if USE_BAROMETER
void ins_alt_float_update_baro(float pressure)
{
  // timestamp in usec when last callback was received
  static uint32_t last_ts = 0;
  // current timestamp
  uint32_t now_ts = get_sys_time_usec();
  // dt between this and last callback in seconds
  float dt = (float)(now_ts - last_ts) / 1e6;
  last_ts = now_ts;
 
  // bound dt (assume baro freq 1Hz-500Hz
  Bound(dt, 0.002, 1.0)
 
  if (!ins_altf.baro_initialized) {
    ins_altf.qfe = pressure;
    ins_altf.baro_initialized = true;
  }
  if (ins_altf.reset_alt_ref) {
    ins_altf.reset_alt_ref = false;
    ins_altf.alt = ground_alt;
    ins_altf.alt_dot = 0.0f;
    ins_altf.qfe = pressure;
    alt_kalman_reset();
  } else { /* not realigning, so normal update with baro measurement */
    ins_altf.baro_alt = ground_alt + pprz_isa_height_of_pressure(pressure, ins_altf.qfe);
    /* run the filter */
    alt_kalman(ins_altf.baro_alt, dt);
    /* set new altitude, just copy old horizontal position */
    struct UtmCoor_f utm;
    UTM_COPY(utm, *stateGetPositionUtm_f());
    utm.alt = ins_altf.alt;
    stateSetPositionUtm_f(&utm);
    struct NedCoor_f ned_vel;
    ned_vel = *stateGetSpeedNed_f();
    ned_vel.z = -ins_altf.alt_dot;
    stateSetSpeedNed_f(&ned_vel);
  }
}
#else
void ins_alt_float_update_baro(float pressure __attribute__((unused)))
{
}
#endif
 
 
void ins_alt_float_update_gps(struct GpsState *gps_s __attribute__((unused)))
{
#if USE_GPS
  if (gps_s->fix < GPS_FIX_3D) {
    return;
  }
 
  if (!ins_altf.origin_initialized) {
    ins_reset_local_origin();
  }
 
  struct UtmCoor_f utm = utm_float_from_gps(gps_s, nav_utm_zone0);
  struct NedCoor_f ned_vel = ned_vel_float_from_gps(gps_s);
 
#if !USE_BAROMETER
#ifdef GPS_DT
  const float dt = GPS_DT;
#else
  // timestamp in usec when last callback was received
  static uint32_t last_ts = 0;
  // current timestamp
  uint32_t now_ts = get_sys_time_usec();
  // dt between this and last callback in seconds
  float dt = (float)(now_ts - last_ts) / 1e6;
  last_ts = now_ts;
 
  // bound dt (assume GPS freq between 0.5Hz and 50Hz)
  Bound(dt, 0.02, 2)
#endif
 
  if (ins_altf.reset_alt_ref) {
    ins_altf.reset_alt_ref = false;
    ins_altf.alt = utm.alt;
    ins_altf.alt_dot = 0.0f;
    alt_kalman_reset();
  } else {
    alt_kalman(utm.alt, dt);
    ins_altf.alt_dot = -ned_vel.z;
  }
#endif // !USE_BAROMETER
 
  utm.alt = ins_altf.alt;
  // set position
  stateSetPositionUtm_f(&utm);
 
  ned_vel.z = -ins_altf.alt_dot; // vz (down) from filter
  // set velocity
  stateSetSpeedNed_f(&ned_vel);
 
#endif
}
 
 
#define GPS_SIGMA2 1.
#define GPS_R 2.
 
static float p[2][2];
 
static void alt_kalman_reset(void)
{
  p[0][0] = 1.0f;
  p[0][1] = 0.0f;
  p[1][0] = 0.0f;
  p[1][1] = 1.0f;
}
 
static void alt_kalman_init(void)
{
  alt_kalman_reset();
}
 
static void alt_kalman(float z_meas, float dt)
{
  float R = GPS_R;
  float SIGMA2 = GPS_SIGMA2;
 
#if USE_BAROMETER
#ifdef SITL
  R = 0.5;
  SIGMA2 = 0.1;
#elif USE_BARO_MS5534A
  if (alt_baro_enabled) {
    R = baro_MS5534A_r;
    SIGMA2 = baro_MS5534A_sigma2;
  }
#elif USE_BARO_ETS
  if (baro_ets_enabled) {
    R = baro_ets_r;
    SIGMA2 = baro_ets_sigma2;
  }
#elif USE_BARO_MS5611
  if (baro_ms5611_enabled) {
    R = baro_ms5611_r;
    SIGMA2 = baro_ms5611_sigma2;
  }
#elif USE_BARO_AMSYS
  if (baro_amsys_enabled) {
    R = baro_amsys_r;
    SIGMA2 = baro_amsys_sigma2;
  }
#elif USE_BARO_BMP
  if (baro_bmp_enabled) {
    R = baro_bmp_r;
    SIGMA2 = baro_bmp_sigma2;
  }
#endif
#endif // USE_BAROMETER
 
  float q[2][2];
  q[0][0] = dt * dt * dt * dt / 4.;
  q[0][1] = dt * dt * dt / 2.;
  q[1][0] = dt * dt * dt / 2.;
  q[1][1] = dt * dt;
 
 
  /* predict */
  ins_altf.alt += ins_altf.alt_dot * dt;
  p[0][0] = p[0][0] + p[1][0] * dt + dt * (p[0][1] + p[1][1] * dt) + SIGMA2 * q[0][0];
  p[0][1] = p[0][1] + p[1][1] * dt + SIGMA2 * q[0][1];
  p[1][0] = p[1][0] + p[1][1] * dt + SIGMA2 * q[1][0];
  p[1][1] = p[1][1] + SIGMA2 * q[1][1];
 
  /* error estimate */
  float e = p[0][0] + R;
 
  if (fabs(e) > 1e-5) {
    float k_0 = p[0][0] / e;
    float k_1 =  p[1][0] / e;
    e = z_meas - ins_altf.alt;
 
    /* correction */
    ins_altf.alt += k_0 * e;
    ins_altf.alt_dot += k_1 * e;
 
    p[1][0] = -p[0][0] * k_1 + p[1][0];
    p[1][1] = -p[0][1] * k_1 + p[1][1];
    p[0][0] = p[0][0] * (1 - k_0);
    p[0][1] = p[0][1] * (1 - k_0);
  }
 
#ifdef DEBUG_ALT_KALMAN
  DOWNLINK_SEND_ALT_KALMAN(DefaultChannel, DefaultDevice, &(p[0][0]), &(p[0][1]), &(p[1][0]), &(p[1][1]));
#endif
}
 
#if USE_BAROMETER
static void baro_cb(uint8_t __attribute__((unused)) sender_id, __attribute__((unused)) uint32_t stamp, float pressure)
{
  ins_alt_float_update_baro(pressure);
}
#endif
 
static void gps_cb(uint8_t sender_id __attribute__((unused)),
                   uint32_t stamp __attribute__((unused)),
                   struct GpsState *gps_s)
{
  ins_alt_float_update_gps(gps_s);
}
 
static void accel_cb(uint8_t sender_id __attribute__((unused)),
                     uint32_t stamp __attribute__((unused)),
                     struct Int32Vect3 *accel)
{
  // untilt accel and remove gravity
  struct Int32Vect3 accel_ned;
  stateSetAccelBody_i(accel);
  struct Int32RMat *ned_to_body_rmat = stateGetNedToBodyRMat_i();
  int32_rmat_transp_vmult(&accel_ned, ned_to_body_rmat, accel);
  accel_ned.z += ACCEL_BFP_OF_REAL(9.81);
  stateSetAccelNed_i((struct NedCoor_i *)&accel_ned);
}