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terrain_est: Continuously reset terrain height on ground using known

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clearance. This is the best estimate as we should not rely on a distance
sensor while on the ground. This also helps when the drone is carried
over as it avoids starting with a crazy downward distance for optical
flow scaling.
This commit is contained in:
bresch 2019-10-03 18:01:02 +02:00 committed by Paul Riseborough
parent e09e3e17a1
commit 370e04ee60
1 changed files with 23 additions and 12 deletions
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35
EKF/terrain_estimator.cpp
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@ -45,33 +45,44 @@
bool Ekf::initHagl()
{
bool initialized = false;
// get most recent range measurement from buffer
const rangeSample &latest_measurement = _range_buffer.get_newest();
if (!_rng_hgt_faulty && (_time_last_imu - latest_measurement.time_us) < (uint64_t)2e5 && _R_rng_to_earth_2_2 > _params.range_cos_max_tilt) {
if (!_control_status.flags.in_air) {
// if on ground, do not trust the range sensor, but assume a ground clearance
_terrain_vpos = _state.pos(2) + _params.rng_gnd_clearance;
// use the ground clearance value as our uncertainty
_terrain_var = sq(_params.rng_gnd_clearance);
initialized = true;
} else if (!_rng_hgt_faulty
&& (_time_last_imu - latest_measurement.time_us) < (uint64_t)2e5
&& _R_rng_to_earth_2_2 > _params.range_cos_max_tilt) {
// if we have a fresh measurement, use it to initialise the terrain estimator
_terrain_vpos = _state.pos(2) + latest_measurement.rng * _R_rng_to_earth_2_2;
// initialise state variance to variance of measurement
_terrain_var = sq(_params.range_noise);
// success
return true;
initialized = true;
} else if (_flow_for_terrain_data_ready) {
// initialise terrain vertical position to origin as this is the best guess we have
_terrain_vpos = fmaxf(0.0f, _state.pos(2));
_terrain_var = 100.0f;
return true;
} else if (!_control_status.flags.in_air) {
// if on ground we assume a ground clearance
_terrain_vpos = _state.pos(2) + _params.rng_gnd_clearance;
// Use the ground clearance value as our uncertainty
_terrain_var = sq(_params.rng_gnd_clearance);
// this is a guess
return true;
initialized = true;
} else {
// no information - cannot initialise
return false;
initialized = false;
}
if (initialized) {
// has initialized with valid data
_time_last_hagl_fuse = _time_last_imu;
}
return initialized;
}
void Ekf::runTerrainEstimator()
@ -80,7 +91,7 @@ void Ekf::runTerrainEstimator()
checkRangeDataContinuity();
// Perform initialisation check
if (!_terrain_initialised) {
if (!_terrain_initialised || !_control_status.flags.in_air) {
_terrain_initialised = initHagl();
} else {