/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- /** * * ekf_check.pde - detects failures of the ekf or inertial nav system * triggers an alert to the pilot and helps take countermeasures * */ #ifndef EKF_CHECK_ITERATIONS_MAX # define EKF_CHECK_ITERATIONS_MAX 10 // 1 second (ie. 10 iterations at 10hz) of bad variances signals a failure #endif #ifndef EKF_CHECK_COMPASS_INAV_CONVERSION # define EKF_CHECK_COMPASS_INAV_CONVERSION 0.01f // converts the inertial nav's acceleration corrections to a form that is comparable to the ekf variance #endif #ifndef EKF_CHECK_WARNING_TIME # define EKF_CHECK_WARNING_TIME (30*1000) // warning text messages are sent to ground no more than every 30 seconds #endif //////////////////////////////////////////////////////////////////////////////// // EKF_check strucutre //////////////////////////////////////////////////////////////////////////////// static struct { uint8_t fail_count_compass; // number of iterations ekf's compass variance has been out of tolerances uint8_t bad_compass : 1; // true if compass variance is bad uint32_t last_warn_time; // system time of last warning in milliseconds. Used to throttle text warnings sent to GCS } ekf_check_state; // ekf_check - detects ekf variances that are out of tolerance // should be called at 10hz void ekf_check() { // return immediately if motors are not armed, ekf check is disabled, no inertial-nav position yet or usb is connected if (!motors.armed() || g.ekfcheck_thresh == 0.0f || !inertial_nav.position_ok() || ap.usb_connected) { ekf_check_state.fail_count_compass = 0; ekf_check_state.bad_compass = 0; AP_Notify::flags.ekf_bad = ekf_check_state.bad_compass; failsafe_ekf_off_event(); // clear failsafe return; } // variances float compass_variance = 0; float vel_variance = 9.0; // default set high to enable failsafe trigger if not using EKF #if AP_AHRS_NAVEKF_AVAILABLE if (ahrs.have_inertial_nav()) { // use EKF to get variance float posVar, hgtVar, tasVar; Vector3f magVar; Vector2f offset; ahrs.get_NavEKF().getVariances(vel_variance, posVar, hgtVar, magVar, tasVar, offset); compass_variance = magVar.length(); } else { // use complementary filter's acceleration corrections multiplied by conversion factor to make them general in the same range as the EKF's variances compass_variance = safe_sqrt(inertial_nav.accel_correction_hbf.x * inertial_nav.accel_correction_hbf.x + inertial_nav.accel_correction_hbf.y * inertial_nav.accel_correction_hbf.y) * EKF_CHECK_COMPASS_INAV_CONVERSION; } #else // use complementary filter's acceleration corrections multiplied by conversion factor to make them general in the same range as the EKF's variances compass_variance = safe_sqrt(inertial_nav.accel_correction_hbf.x * inertial_nav.accel_correction_hbf.x + inertial_nav.accel_correction_hbf.y * inertial_nav.accel_correction_hbf.y) * EKF_CHECK_COMPASS_INAV_CONVERSION; #endif // compare compass and velocity variance vs threshold if (compass_variance >= g.ekfcheck_thresh && vel_variance > g.ekfcheck_thresh) { // if compass is not yet flagged as bad if (!ekf_check_state.bad_compass) { // increase counter ekf_check_state.fail_count_compass++; // if counter above max then trigger failsafe if (ekf_check_state.fail_count_compass >= EKF_CHECK_ITERATIONS_MAX) { // limit count from climbing too high ekf_check_state.fail_count_compass = EKF_CHECK_ITERATIONS_MAX; ekf_check_state.bad_compass = true; // log an error in the dataflash Log_Write_Error(ERROR_SUBSYSTEM_EKF_CHECK, ERROR_CODE_EKF_CHECK_BAD_COMPASS); // send message to gcs if ((hal.scheduler->millis() - ekf_check_state.last_warn_time) > EKF_CHECK_WARNING_TIME) { gcs_send_text_P(SEVERITY_HIGH,PSTR("EKF variance")); ekf_check_state.last_warn_time = hal.scheduler->millis(); } failsafe_ekf_event(); } } } else { // if compass is flagged as bad if (ekf_check_state.bad_compass) { // reduce counter ekf_check_state.fail_count_compass--; // if counter reaches zero then clear flag if (ekf_check_state.fail_count_compass == 0) { ekf_check_state.bad_compass = false; // log recovery in the dataflash Log_Write_Error(ERROR_SUBSYSTEM_EKF_CHECK, ERROR_CODE_EKF_CHECK_BAD_COMPASS_CLEARED); // clear failsafe failsafe_ekf_off_event(); } } } // set AP_Notify flags AP_Notify::flags.ekf_bad = ekf_check_state.bad_compass; // To-Do: add check for althold when vibrations are high // To-Do: add ekf variances to extended status // To-Do: add counter measures to try and recover from bad EKF // To-Do: add check into GPS position_ok() to return false if ekf xy not healthy? // To-Do: ensure it compiles for AVR } // failsafe_ekf_event - perform ekf failsafe static void failsafe_ekf_event() { // return immediately if ekf failsafe already triggered or disabled if (failsafe.ekf || g.ekfcheck_thresh <= 0.0f) { return; } // do nothing if motors disarmed or not in flight mode that requires GPS if (!motors.armed() || !mode_requires_GPS(control_mode)) { return; } // EKF failsafe event has occurred failsafe.ekf = true; Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_EKF, ERROR_CODE_FAILSAFE_OCCURRED); // take action based on flight mode if (mode_requires_GPS(control_mode)) { set_mode_land_with_pause(); } // if flight mode is LAND ensure it's not the GPS controlled LAND if (control_mode == LAND) { land_do_not_use_GPS(); } } // failsafe_ekf_off_event - actions to take when EKF failsafe is cleared static void failsafe_ekf_off_event(void) { // return immediately if not in ekf failsafe if (!failsafe.ekf) { return; } // clear flag and log recovery failsafe.ekf = false; Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_EKF, ERROR_CODE_FAILSAFE_RESOLVED); }