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Merge pull request #334 from PX4/pr-ekf_minor_flow_fix 

ekf: fix optical flow bugs
This commit is contained in:
Paul Riseborough 2017-10-12 09:14:29 +11:00 committed by GitHub
parent 68bad48598 4db23b7b2e
commit 9c65968c3d
3 changed files with 33 additions and 23 deletions
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34
EKF/control.cpp
View File

@ -300,6 +300,7 @@ void Ekf::controlOpticalFlowFusion()
// set the flag and reset the fusion timeout
_control_status.flags.opt_flow = true;
_time_last_of_fuse = _time_last_imu;
ECL_INFO("EKF Starting Optical Flow Use");
// if we are not using GPS then the velocity and position states and covariances need to be set
if (!_control_status.flags.gps) {
@ -365,26 +366,12 @@ void Ekf::controlOpticalFlowFusion()
}
// handle the case when we are relying on optical flow fusion and lose it
if (_control_status.flags.opt_flow && !_control_status.flags.gps && !_control_status.flags.ev_pos) {
// We are relying on flow aiding to constrain attitude drift so after 5s without aiding we need to do something
if ((_time_last_imu - _time_last_of_fuse > 5e6)) {
// Switch to the non-aiding mode, zero the velocity states
// and set the synthetic position to the current estimate
_control_status.flags.opt_flow = false;
_last_known_posNE(0) = _state.pos(0);
_last_known_posNE(1) = _state.pos(1);
_state.vel.setZero();
}
}
// Accumulate autopilot gyro data across the same time interval as the flow sensor
_imu_del_ang_of += _imu_sample_delayed.delta_ang - _state.gyro_bias;
_delta_time_of += _imu_sample_delayed.delta_ang_dt;
// fuse the data
if (_control_status.flags.opt_flow) {
// fuse the data if the terrain/distance to bottom is valid
if (_control_status.flags.opt_flow && get_terrain_valid()) {
// Update optical flow bias estimates
calcOptFlowBias();
@ -395,6 +382,21 @@ void Ekf::controlOpticalFlowFusion()
}
}
// handle the case when we are relying on optical flow fusion and lose it
if (_control_status.flags.opt_flow && !_control_status.flags.gps && !_control_status.flags.ev_pos) {
// We are relying on flow aiding to constrain attitude drift so after 5s without aiding we need to do something
if ((_time_last_imu - _time_last_of_fuse > 5e6)) {
// Switch to the non-aiding mode, zero the velocity states
// and set the synthetic position to the current estimate
_control_status.flags.opt_flow = false;
_last_known_posNE(0) = _state.pos(0);
_last_known_posNE(1) = _state.pos(1);
_state.vel.setZero();
ECL_WARN("EKF Stopping Optical Flow Use");
}
}
}
void Ekf::controlGpsFusion()

20
EKF/estimator_interface.cpp
View File

@ -278,11 +278,17 @@ void EstimatorInterface::setOpticalFlowData(uint64_t time_usec, flow_message *fl
// check if enough integration time and fail if integration time is less than 50%
// of min arrival interval because too much data is being lost
float delta_time = 1e-6f * (float)flow->dt;
bool delta_time_good = (delta_time >= 5e-7f * (float)_min_obs_interval_us);
float delta_time_min = 5e-7f * (float)_min_obs_interval_us;
bool delta_time_good = delta_time >= delta_time_min;
if (!delta_time_good) {
// protect against overflow casued by division with very small delta_time
delta_time = delta_time_min;
}
// check magnitude is within sensor limits
float flow_rate_magnitude;
bool flow_magnitude_good = false;
bool flow_magnitude_good = true;
if (delta_time_good) {
flow_rate_magnitude = flow->flowdata.norm() / delta_time;
@ -292,7 +298,9 @@ void EstimatorInterface::setOpticalFlowData(uint64_t time_usec, flow_message *fl
// check quality metric
bool flow_quality_good = (flow->quality >= _params.flow_qual_min);
if (delta_time_good && flow_magnitude_good && (flow_quality_good || !_control_status.flags.in_air)) {
// Always use data when on ground to allow for bad quality due to unfocussed sensors and operator handling
// If flow quality fails checks on ground, assume zero flow rate after body rate compensation
if ((delta_time_good && flow_quality_good && flow_magnitude_good) || !_control_status.flags.in_air) {
flowSample optflow_sample_new;
// calculate the system time-stamp for the mid point of the integration period
optflow_sample_new.time_us = time_usec - _params.flow_delay_ms * 1000 - flow->dt / 2;
@ -307,8 +315,8 @@ void EstimatorInterface::setOpticalFlowData(uint64_t time_usec, flow_message *fl
} else {
// when on the ground with poor flow quality, assume zero ground relative velocity
optflow_sample_new.flowRadXY(0) = + flow->gyrodata(0);
optflow_sample_new.flowRadXY(1) = + flow->gyrodata(1);
optflow_sample_new.flowRadXY(0) = - flow->gyrodata(0);
optflow_sample_new.flowRadXY(1) = - flow->gyrodata(1);
}
@ -316,7 +324,7 @@ void EstimatorInterface::setOpticalFlowData(uint64_t time_usec, flow_message *fl
optflow_sample_new.flowRadXYcomp(0) = optflow_sample_new.flowRadXY(0) - optflow_sample_new.gyroXYZ(0);
optflow_sample_new.flowRadXYcomp(1) = optflow_sample_new.flowRadXY(1) - optflow_sample_new.gyroXYZ(1);
// convert integration interval to seconds
optflow_sample_new.dt = 1e-6f * (float)flow->dt;
optflow_sample_new.dt = delta_time;
_time_last_optflow = time_usec;
// push to buffer
_flow_buffer.push(optflow_sample_new);

2
EKF/terrain_estimator.cpp
View File

@ -159,7 +159,7 @@ void Ekf::fuseHagl()
bool Ekf::get_terrain_valid()
{
if (_terrain_initialised && _range_data_continuous && !_rng_stuck &&
!_innov_check_fail_status.flags.reject_hagl) {
(_time_last_imu - _time_last_hagl_fuse < 5E6)) {
return true;
} else {