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author | Mark Whitehorn <kd0aij@gmail.com> | 2014-12-22 13:47:20 -0700 |
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committer | Mark Whitehorn <kd0aij@gmail.com> | 2015-01-13 09:06:00 -0700 |
commit | 3c98c7119ebe956d1dc9c10379e9158567d16642 (patch) | |
tree | 91f45457740a6c19d2afbd46b48ed7823014cb21 /src/modules/ekf_att_pos_estimator | |
parent | 78b603bb3532e927e617fe1946a1090b509e72ad (diff) | |
download | px4-firmware-3c98c7119ebe956d1dc9c10379e9158567d16642.tar.gz px4-firmware-3c98c7119ebe956d1dc9c10379e9158567d16642.tar.bz2 px4-firmware-3c98c7119ebe956d1dc9c10379e9158567d16642.zip |
use non-uniform 1st order IIR lowpass filters for baro_gps_offset estimation
Diffstat (limited to 'src/modules/ekf_att_pos_estimator')
-rw-r--r-- | src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp | 59 |
1 files changed, 52 insertions, 7 deletions
diff --git a/src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp b/src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp index c41777968..1770a75e5 100644 --- a/src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp +++ b/src/modules/ekf_att_pos_estimator/ekf_att_pos_estimator_main.cpp @@ -82,12 +82,11 @@ #include <systemlib/perf_counter.h> #include <systemlib/systemlib.h> #include <mathlib/mathlib.h> +#include <mathlib/math/filter/LowPassFilter2p.hpp> #include <mavlink/mavlink_log.h> #include "estimator_23states.h" - - /** * estimator app start / stop handling function * @@ -101,7 +100,7 @@ __EXPORT uint64_t getMicros(); static uint64_t IMUmsec = 0; static uint64_t IMUusec = 0; -static const uint64_t FILTER_INIT_DELAY = 1 * 1000 * 1000; +static const uint64_t FILTER_INIT_DELAY = 1 * 1000 * 1000; // units: microseconds uint32_t millis() { @@ -222,8 +221,10 @@ private: float _baro_ref; /**< barometer reference altitude */ float _baro_ref_offset; /**< offset between initial baro reference and GPS init baro altitude */ float _baro_gps_offset; /**< offset between baro altitude (at GPS init time) and GPS altitude */ + hrt_abstime _last_debug_print = 0; perf_counter_t _loop_perf; ///< loop performance counter + perf_counter_t _loop_intvl; ///< loop rate counter perf_counter_t _perf_gyro; ///<local performance counter for gyro updates perf_counter_t _perf_mag; ///<local performance counter for mag updates perf_counter_t _perf_gps; ///<local performance counter for gps updates @@ -399,6 +400,7 @@ FixedwingEstimator::FixedwingEstimator() : /* performance counters */ _loop_perf(perf_alloc(PC_ELAPSED, "ekf_att_pos_estimator")), + _loop_intvl(perf_alloc(PC_INTERVAL, "ekf_att_pos_est_interval")), _perf_gyro(perf_alloc(PC_INTERVAL, "ekf_att_pos_gyro_upd")), _perf_mag(perf_alloc(PC_INTERVAL, "ekf_att_pos_mag_upd")), _perf_gps(perf_alloc(PC_INTERVAL, "ekf_att_pos_gps_upd")), @@ -782,6 +784,12 @@ FixedwingEstimator::task_main() _gps.vel_e_m_s = 0.0f; _gps.vel_d_m_s = 0.0f; + // init lowpass filters for baro and gps altitude + float _gps_alt_filt = 0, _baro_alt_filt = 0; + float _gps_last = 0, _baro_last = 0; + float rc = (1.0f/10); // actually 1/RC time constant of 1st order LPF + hrt_abstime baro_last = 0; + _task_running = true; while (!_task_should_exit) { @@ -800,6 +808,7 @@ FixedwingEstimator::task_main() } perf_begin(_loop_perf); + perf_count(_loop_intvl); /* only update parameters if they changed */ if (fds[0].revents & POLLIN) { @@ -1055,6 +1064,12 @@ FixedwingEstimator::task_main() _ekf->gpsLon = math::radians(_gps.lon / (double)1e7) - M_PI; _ekf->gpsHgt = _gps.alt / 1e3f; + // update LPF + _gps_alt_filt += (1 - expf(-gps_elapsed * rc)) * (_gps_last - _gps_alt_filt); + _gps_last = _ekf->gpsHgt; + + //warnx("gps alt: %6.1f, interval: %6.3f", (double)_ekf->gpsHgt, (double)gps_elapsed); + // if (_gps.s_variance_m_s > 0.25f && _gps.s_variance_m_s < 100.0f * 100.0f) { // _ekf->vneSigma = sqrtf(_gps.s_variance_m_s); // } else { @@ -1070,7 +1085,6 @@ FixedwingEstimator::task_main() // warnx("vel: %8.4f pos: %8.4f", _gps.s_variance_m_s, _gps.p_variance_m); newDataGps = true; - last_gps = _gps.timestamp_position; } @@ -1082,15 +1096,16 @@ FixedwingEstimator::task_main() if (baro_updated) { - hrt_abstime baro_last = _baro.timestamp; - orb_copy(ORB_ID(sensor_baro0), _baro_sub, &_baro); float baro_elapsed = (_baro.timestamp - baro_last) / 1e6f; + baro_last = _baro.timestamp; _ekf->updateDtHgtFilt(math::constrain(baro_elapsed, 0.001f, 0.1f)); _ekf->baroHgt = _baro.altitude; + _baro_alt_filt += (1 - expf(-baro_elapsed * rc)) * (_baro_last - _baro_alt_filt); + _baro_last = _baro.altitude; if (!_baro_init) { _baro_ref = _baro.altitude; @@ -1180,6 +1195,24 @@ FixedwingEstimator::task_main() float initVelNED[3]; + // maintain filtered baro and gps altitudes to calculate weather offset + // baro sample rate is ~70Hz and measurement bandwidth is high + // gps sample rate is 5Hz and altitude is assumed accurate when averaged over 30 seconds + // maintain heavily filtered values for both baro and gps altitude + // Assume the filtered output should be identical for both sensors + _baro_gps_offset = _baro_alt_filt - _gps_alt_filt; + if (hrt_elapsed_time(&_last_debug_print) >= 5e6) { + _last_debug_print = hrt_absolute_time(); + perf_print_counter(_perf_baro); + perf_reset(_perf_baro); + warnx("gpsoff: %5.1f, baro_alt_filt: %6.1f, gps_alt_filt: %6.1f, gpos.alt: %5.1f, lpos.z: %6.1f", + (double)_baro_gps_offset, + (double)_baro_alt_filt, + (double)_gps_alt_filt, + (double)_global_pos.alt, + (double)_local_pos.z); + } + /* Initialize the filter first */ if (!_gps_initialized && _gps.fix_type > 2 && _gps.eph < _parameters.pos_stddev_threshold && _gps.epv < _parameters.pos_stddev_threshold) { @@ -1195,7 +1228,13 @@ FixedwingEstimator::task_main() // Set up height correctly orb_copy(ORB_ID(sensor_baro0), _baro_sub, &_baro); _baro_ref_offset = _ekf->states[9]; // this should become zero in the local frame - _baro_gps_offset = _baro.altitude - gps_alt; + + // init filtered gps and baro altitudes + _gps_alt_filt = gps_alt; + _gps_last = gps_alt; + _baro_alt_filt = _baro.altitude; + _baro_last = _baro.altitude; + _ekf->baroHgt = _baro.altitude; _ekf->hgtMea = 1.0f * (_ekf->baroHgt - (_baro_ref)); @@ -1502,6 +1541,12 @@ FixedwingEstimator::task_main() _global_pos.timestamp = _local_pos.timestamp; + // FIXME: usurp terrain alt field for baro_gps_offset + _global_pos.terrain_alt = _baro_gps_offset; + _global_pos.terrain_alt_valid = true; + _global_pos.eph = _baro_alt_filt; + _global_pos.epv = _gps_alt_filt; + /* lazily publish the global position only once available */ if (_global_pos_pub > 0) { /* publish the global position */ |