diff --git a/EKF/ekf_helper.cpp b/EKF/ekf_helper.cpp index 554796be26..12ec0a9d2e 100644 --- a/EKF/ekf_helper.cpp +++ b/EKF/ekf_helper.cpp @@ -792,6 +792,21 @@ void Ekf::get_ekf_vel_accuracy(float *ekf_evh, float *ekf_evv, bool *dead_reckon // report dead reckoning if it is more than a second since we fused in measurements that constrain velocity drift bool is_dead_reckoning = (_time_last_imu - _time_last_pos_fuse > 1e6) && (_time_last_imu - _time_last_vel_fuse > 1e6) && (_time_last_imu - _time_last_of_fuse > 1e6); + // If we are dead-reckoning, use the innovations as a conservative alternate measure of the horizontal velocity error + // The reason is that complete rejection of measurements is often be casued by heading misalignment or inertial sensing errors + // and using state variances for accuracy reporting provides an overly optimistic assessment in these situations + float vel_err_alt = 0.0f; + if (dead_reckoning) { + if (_control_status.flags.opt_flow) { + float gndclearance = math::max(_params.rng_gnd_clearance, 0.1f); + vel_err_alt = math::max((_terrain_vpos - _state.pos(2)), gndclearance) * sqrtf(_flow_innov[0]*_flow_innov[0] + _flow_innov[1]*_flow_innov[1]); + } + if (_control_status.flags.gps || _control_status.flags.ev_pos) { + vel_err_alt = math::max(vel_err_alt, sqrtf(_vel_pos_innov[0]*_vel_pos_innov[0] + _vel_pos_innov[1]*_vel_pos_innov[1])); + } + hvel_err = math::max(hvel_err, vel_err_alt); + } + memcpy(ekf_evh, &hvel_err, sizeof(float)); memcpy(ekf_evv, &vvel_err, sizeof(float)); memcpy(dead_reckoning, &is_dead_reckoning, sizeof(bool));