position_estimator_inav: failsafe against NaN estimate

src/modules/position_estimator_inav/position_estimator_inav_main.c

@@ -708,6 +708,11 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 		inertial_filter_correct(corr_gps[2][0], dt, z_est, 0, w_z_gps_p);
 		inertial_filter_correct(corr_acc[2], dt, z_est, 2, params.w_z_acc);
 
+		float x_est_prev[3], y_est_prev[3];
+
+		memcpy(x_est_prev, x_est, sizeof(x_est));
+		memcpy(y_est_prev, y_est, sizeof(y_est));
+
 		if (can_estimate_xy) {
 			/* inertial filter prediction for position */
 			inertial_filter_predict(dt, x_est);
@@ -715,7 +720,8 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 			if (!isfinite(x_est[0]) || !isfinite(y_est[0])) {
 				write_debug_log("BAD ESTIMATE AFTER PREDICTION", dt, x_est, y_est, z_est, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
-				thread_should_exit = true;
+				memcpy(x_est, x_est_prev, sizeof(x_est));
+				memcpy(y_est, y_est_prev, sizeof(y_est));
 			}
 
 			/* inertial filter correction for position */
@@ -739,7 +745,11 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 			if (!isfinite(x_est[0]) || !isfinite(y_est[0])) {
 				write_debug_log("BAD ESTIMATE AFTER CORRECTION", dt, x_est, y_est, z_est, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
-				thread_should_exit = true;
+				memcpy(x_est, x_est_prev, sizeof(x_est));
+				memcpy(y_est, y_est_prev, sizeof(y_est));
+				memset(corr_acc, 0, sizeof(corr_acc));
+				memset(corr_gps, 0, sizeof(corr_gps));
+				memset(corr_flow, 0, sizeof(corr_flow));
 			}
 		}