Merge pull request #256 from rk3dov/6point_accel_calibration

6point accel calibration

3 files changed, 434 insertions, 123 deletions

diff --git a/apps/commander/accelerometer_calibration.c b/apps/commander/accelerometer_calibration.c
new file mode 100644
index 000000000..991145d73
--- /dev/null
+++ b/apps/commander/accelerometer_calibration.c
@@ -0,0 +1,416 @@
+/*
+ * accelerometer_calibration.c
+ *
+ *   Copyright (C) 2013 Anton Babushkin. All rights reserved.
+ *   Author: 	Anton Babushkin	<rk3dov@gmail.com>
+ *
+ * Transform acceleration vector to true orientation and scale
+ *
+ * * * * Model * * *
+ * accel_corr = accel_T * (accel_raw - accel_offs)
+ *
+ * accel_corr[3] - fully corrected acceleration vector in body frame
+ * accel_T[3][3] - accelerometers transform matrix, rotation and scaling transform
+ * accel_raw[3]  - raw acceleration vector
+ * accel_offs[3] - acceleration offset vector
+ *
+ * * * * Calibration * * *
+ *
+ * Reference vectors
+ * accel_corr_ref[6][3] = [  g  0  0 ]     // nose up
+ *                        | -g  0  0 |     // nose down
+ *                        |  0  g  0 |     // left side down
+ *                        |  0 -g  0 |     // right side down
+ *                        |  0  0  g |     // on back
+ *                        [  0  0 -g ]     // level
+ * accel_raw_ref[6][3]
+ *
+ * accel_corr_ref[i] = accel_T * (accel_raw_ref[i] - accel_offs), i = 0...5
+ *
+ * 6 reference vectors * 3 axes = 18 equations
+ * 9 (accel_T) + 3 (accel_offs) = 12 unknown constants
+ *
+ * Find accel_offs
+ *
+ * accel_offs[i] = (accel_raw_ref[i*2][i] + accel_raw_ref[i*2+1][i]) / 2
+ *
+ *
+ * Find accel_T
+ *
+ * 9 unknown constants
+ * need 9 equations -> use 3 of 6 measurements -> 3 * 3 = 9 equations
+ *
+ * accel_corr_ref[i*2] = accel_T * (accel_raw_ref[i*2] - accel_offs), i = 0...2
+ *
+ * Solve separate system for each row of accel_T:
+ *
+ * accel_corr_ref[j*2][i] = accel_T[i] * (accel_raw_ref[j*2] - accel_offs), j = 0...2
+ *
+ * A * x = b
+ *
+ * x = [ accel_T[0][i] ]
+ *     | accel_T[1][i] |
+ *     [ accel_T[2][i] ]
+ *
+ * b = [ accel_corr_ref[0][i] ]	// One measurement per axis is enough
+ *     | accel_corr_ref[2][i] |
+ *     [ accel_corr_ref[4][i] ]
+ *
+ * a[i][j] = accel_raw_ref[i][j] - accel_offs[j], i = 0;2;4, j = 0...2
+ *
+ * Matrix A is common for all three systems:
+ * A = [ a[0][0]  a[0][1]  a[0][2] ]
+ *     | a[2][0]  a[2][1]  a[2][2] |
+ *     [ a[4][0]  a[4][1]  a[4][2] ]
+ *
+ * x = A^-1 * b
+ *
+ * accel_T = A^-1 * g
+ * g = 9.80665
+ */
+
+#include "accelerometer_calibration.h"
+
+#include <poll.h>
+#include <drivers/drv_hrt.h>
+#include <uORB/topics/sensor_combined.h>
+#include <drivers/drv_accel.h>
+#include <systemlib/conversions.h>
+#include <mavlink/mavlink_log.h>
+
+void do_accel_calibration(int status_pub, struct vehicle_status_s *status, int mavlink_fd);
+int do_accel_calibration_mesurements(int mavlink_fd, float accel_offs[3], float accel_scale[3]);
+int detect_orientation(int mavlink_fd, int sub_sensor_combined);
+int read_accelerometer_avg(int sensor_combined_sub, float accel_avg[3], int samples_num);
+int mat_invert3(float src[3][3], float dst[3][3]);
+int calculate_calibration_values(float accel_ref[6][3], float accel_T[3][3], float accel_offs[3], float g);
+
+void do_accel_calibration(int status_pub, struct vehicle_status_s *status, int mavlink_fd) {
+	/* announce change */
+	mavlink_log_info(mavlink_fd, "accel calibration started");
+	/* set to accel calibration mode */
+	status->flag_preflight_accel_calibration = true;
+	state_machine_publish(status_pub, status, mavlink_fd);
+
+	/* measure and calculate offsets & scales */
+	float accel_offs[3];
+	float accel_scale[3];
+	int res = do_accel_calibration_mesurements(mavlink_fd, accel_offs, accel_scale);
+
+	if (res == OK) {
+		/* measurements complete successfully, set parameters */
+		if (param_set(param_find("SENS_ACC_XOFF"), &(accel_offs[0]))
+			|| param_set(param_find("SENS_ACC_YOFF"), &(accel_offs[1]))
+			|| param_set(param_find("SENS_ACC_ZOFF"), &(accel_offs[2]))
+			|| param_set(param_find("SENS_ACC_XSCALE"), &(accel_scale[0]))
+			|| param_set(param_find("SENS_ACC_YSCALE"), &(accel_scale[1]))
+			|| param_set(param_find("SENS_ACC_ZSCALE"), &(accel_scale[2]))) {
+			mavlink_log_critical(mavlink_fd, "ERROR: setting offs or scale failed");
+		}
+
+		int fd = open(ACCEL_DEVICE_PATH, 0);
+		struct accel_scale ascale = {
+			accel_offs[0],
+			accel_scale[0],
+			accel_offs[1],
+			accel_scale[1],
+			accel_offs[2],
+			accel_scale[2],
+		};
+
+		if (OK != ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&ascale))
+			warn("WARNING: failed to set scale / offsets for accel");
+
+		close(fd);
+
+		/* auto-save to EEPROM */
+		int save_ret = param_save_default();
+
+		if (save_ret != 0) {
+			warn("WARNING: auto-save of params to storage failed");
+		}
+
+		mavlink_log_info(mavlink_fd, "accel calibration done");
+		tune_confirm();
+		sleep(2);
+		tune_confirm();
+		sleep(2);
+		/* third beep by cal end routine */
+	} else {
+		/* measurements error */
+		mavlink_log_info(mavlink_fd, "accel calibration aborted");
+		tune_error();
+		sleep(2);
+	}
+
+	/* exit accel calibration mode */
+	status->flag_preflight_accel_calibration = false;
+	state_machine_publish(status_pub, status, mavlink_fd);
+}
+
+int do_accel_calibration_mesurements(int mavlink_fd, float accel_offs[3], float accel_scale[3]) {
+	const int samples_num = 2500;
+	float accel_ref[6][3];
+	bool data_collected[6] = { false, false, false, false, false, false };
+	const char *orientation_strs[6] = { "x+", "x-", "y+", "y-", "z+", "z-" };
+
+	/* reset existing calibration */
+	int fd = open(ACCEL_DEVICE_PATH, 0);
+	struct accel_scale ascale_null = {
+		0.0f,
+		1.0f,
+		0.0f,
+		1.0f,
+		0.0f,
+		1.0f,
+	};
+	int ioctl_res = ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&ascale_null);
+	close(fd);
+
+	if (OK != ioctl_res) {
+		warn("ERROR: failed to set scale / offsets for accel");
+		return ERROR;
+	}
+
+	int sensor_combined_sub = orb_subscribe(ORB_ID(sensor_combined));
+	while (true) {
+		bool done = true;
+		char str[80];
+		int str_ptr;
+		str_ptr = sprintf(str, "keep vehicle still:");
+		for (int i = 0; i < 6; i++) {
+			if (!data_collected[i]) {
+				str_ptr += sprintf(&(str[str_ptr]), " %s", orientation_strs[i]);
+				done = false;
+			}
+		}
+		if (done)
+			break;
+		mavlink_log_info(mavlink_fd, str);
+
+		int orient = detect_orientation(mavlink_fd, sensor_combined_sub);
+		if (orient < 0)
+			return ERROR;
+
+		sprintf(str, "meas started: %s", orientation_strs[orient]);
+		mavlink_log_info(mavlink_fd, str);
+		read_accelerometer_avg(sensor_combined_sub, &(accel_ref[orient][0]), samples_num);
+		str_ptr = sprintf(str, "meas result for %s: [ %.2f %.2f %.2f ]", orientation_strs[orient], accel_ref[orient][0], accel_ref[orient][1], accel_ref[orient][2]);
+		mavlink_log_info(mavlink_fd, str);
+		data_collected[orient] = true;
+		tune_confirm();
+	}
+	close(sensor_combined_sub);
+
+	/* calculate offsets and rotation+scale matrix */
+	float accel_T[3][3];
+	int res = calculate_calibration_values(accel_ref, accel_T, accel_offs, CONSTANTS_ONE_G);
+	if (res != 0) {
+		mavlink_log_info(mavlink_fd, "ERROR: calibration values calc error");
+		return ERROR;
+	}
+
+	/* convert accel transform matrix to scales,
+	 * rotation part of transform matrix is not used by now
+	 */
+	for (int i = 0; i < 3; i++) {
+		accel_scale[i] = accel_T[i][i];
+	}
+
+	return OK;
+}
+
+/*
+ * Wait for vehicle become still and detect it's orientation.
+ *
+ * @return 0..5 according to orientation when vehicle is still and ready for measurements,
+ * ERROR if vehicle is not still after 30s or orientation error is more than 5m/s^2
+ */
+int detect_orientation(int mavlink_fd, int sub_sensor_combined) {
+	struct sensor_combined_s sensor;
+	/* exponential moving average of accel */
+	float accel_ema[3] = { 0.0f, 0.0f, 0.0f };
+	/* max-hold dispersion of accel */
+	float accel_disp[3] = { 0.0f, 0.0f, 0.0f };
+	float accel_len2 = 0.0f;
+	/* EMA time constant in seconds*/
+	float ema_len = 0.2f;
+	/* set "still" threshold to 0.1 m/s^2 */
+	float still_thr2 = pow(0.1f, 2);
+	/* set accel error threshold to 5m/s^2 */
+	float accel_err_thr = 5.0f;
+	/* still time required in us */
+	int64_t still_time = 2000000;
+	struct pollfd fds[1] = { { .fd = sub_sensor_combined, .events = POLLIN } };
+
+	hrt_abstime t_start = hrt_absolute_time();
+	/* set timeout to 30s */
+	hrt_abstime timeout = 30000000;
+	hrt_abstime t_timeout = t_start + timeout;
+	hrt_abstime t = t_start;
+	hrt_abstime t_prev = t_start;
+	hrt_abstime t_still = 0;
+	while (true) {
+		/* wait blocking for new data */
+		int poll_ret = poll(fds, 1, 1000);
+		if (poll_ret) {
+			orb_copy(ORB_ID(sensor_combined), sub_sensor_combined, &sensor);
+			t = hrt_absolute_time();
+			float dt = (t - t_prev) / 1000000.0f;
+			t_prev = t;
+			float w = dt / ema_len;
+			for (int i = 0; i < 3; i++) {
+				accel_ema[i] = accel_ema[i] * (1.0f - w) + sensor.accelerometer_m_s2[i] * w;
+				float d = (float) sensor.accelerometer_m_s2[i] - accel_ema[i];
+				d = d * d;
+				accel_disp[i] = accel_disp[i] * (1.0f - w);
+				if (d > accel_disp[i])
+					accel_disp[i] = d;
+			}
+			/* still detector with hysteresis */
+			if (  accel_disp[0] < still_thr2 &&
+				  accel_disp[1] < still_thr2 &&
+				  accel_disp[2] < still_thr2 ) {
+				/* is still now */
+				if (t_still == 0) {
+					/* first time */
+					mavlink_log_info(mavlink_fd, "still...");
+					t_still = t;
+					t_timeout = t + timeout;
+				} else {
+					/* still since t_still */
+					if ((int64_t) t - (int64_t) t_still > still_time) {
+						/* vehicle is still, exit from the loop to detection of its orientation */
+						break;
+					}
+				}
+			} else if ( accel_disp[0] > still_thr2 * 2.0f ||
+					    accel_disp[1] > still_thr2 * 2.0f ||
+					    accel_disp[2] > still_thr2 * 2.0f) {
+				/* not still, reset still start time */
+				if (t_still != 0) {
+					mavlink_log_info(mavlink_fd, "moving...");
+					t_still = 0;
+				}
+			}
+		} else if (poll_ret == 0) {
+			/* any poll failure for 1s is a reason to abort */
+			mavlink_log_info(mavlink_fd, "ERROR: poll failure");
+			return -3;
+		}
+		if (t > t_timeout) {
+			mavlink_log_info(mavlink_fd, "ERROR: timeout");
+			return -1;
+		}
+	}
+
+	float accel_len = sqrt(accel_len2);
+	if (  fabs(accel_ema[0] - accel_len) < accel_err_thr &&
+		  fabs(accel_ema[1]) < accel_err_thr &&
+		  fabs(accel_ema[2]) < accel_err_thr  )
+		return 0;	// [ g, 0, 0 ]
+	if (  fabs(accel_ema[0] + accel_len) < accel_err_thr &&
+		  fabs(accel_ema[1]) < accel_err_thr &&
+		  fabs(accel_ema[2]) < accel_err_thr  )
+		return 1;	// [ -g, 0, 0 ]
+	if (  fabs(accel_ema[0]) < accel_err_thr &&
+		  fabs(accel_ema[1] - accel_len) < accel_err_thr &&
+		  fabs(accel_ema[2]) < accel_err_thr  )
+		return 2;	// [ 0, g, 0 ]
+	if (  fabs(accel_ema[0]) < accel_err_thr &&
+		  fabs(accel_ema[1] + accel_len) < accel_err_thr &&
+		  fabs(accel_ema[2]) < accel_err_thr  )
+		return 3;	// [ 0, -g, 0 ]
+	if (  fabs(accel_ema[0]) < accel_err_thr &&
+		  fabs(accel_ema[1]) < accel_err_thr &&
+		  fabs(accel_ema[2] - accel_len) < accel_err_thr  )
+		return 4;	// [ 0, 0, g ]
+	if (  fabs(accel_ema[0]) < accel_err_thr &&
+		  fabs(accel_ema[1]) < accel_err_thr &&
+		  fabs(accel_ema[2] + accel_len) < accel_err_thr  )
+		return 5;	// [ 0, 0, -g ]
+
+	mavlink_log_info(mavlink_fd, "ERROR: invalid orientation");
+
+	return -2;	// Can't detect orientation
+}
+
+/*
+ * Read specified number of accelerometer samples, calculate average and dispersion.
+ */
+int read_accelerometer_avg(int sensor_combined_sub, float accel_avg[3], int samples_num) {
+	struct pollfd fds[1] = { { .fd = sensor_combined_sub, .events = POLLIN } };
+	int count = 0;
+	float accel_sum[3] = { 0.0f, 0.0f, 0.0f };
+
+	while (count < samples_num) {
+		int poll_ret = poll(fds, 1, 1000);
+		if (poll_ret == 1) {
+			struct sensor_combined_s sensor;
+			orb_copy(ORB_ID(sensor_combined), sensor_combined_sub, &sensor);
+			for (int i = 0; i < 3; i++)
+				accel_sum[i] += sensor.accelerometer_m_s2[i];
+			count++;
+		} else {
+			return ERROR;
+		}
+	}
+
+	for (int i = 0; i < 3; i++) {
+		accel_avg[i] = accel_sum[i] / count;
+	}
+
+	return OK;
+}
+
+int mat_invert3(float src[3][3], float dst[3][3]) {
+	float det = src[0][0] * (src[1][1] * src[2][2] - src[1][2] * src[2][1]) -
+			    src[0][1] * (src[1][0] * src[2][2] - src[1][2] * src[2][0]) +
+			    src[0][2] * (src[1][0] * src[2][1] - src[1][1] * src[2][0]);
+	if (det == 0.0)
+		return ERROR;	// Singular matrix
+
+	dst[0][0] = (src[1][1] * src[2][2] - src[1][2] * src[2][1]) / det;
+	dst[1][0] = (src[1][2] * src[2][0] - src[1][0] * src[2][2]) / det;
+	dst[2][0] = (src[1][0] * src[2][1] - src[1][1] * src[2][0]) / det;
+	dst[0][1] = (src[0][2] * src[2][1] - src[0][1] * src[2][2]) / det;
+	dst[1][1] = (src[0][0] * src[2][2] - src[0][2] * src[2][0]) / det;
+	dst[2][1] = (src[0][1] * src[2][0] - src[0][0] * src[2][1]) / det;
+	dst[0][2] = (src[0][1] * src[1][2] - src[0][2] * src[1][1]) / det;
+	dst[1][2] = (src[0][2] * src[1][0] - src[0][0] * src[1][2]) / det;
+	dst[2][2] = (src[0][0] * src[1][1] - src[0][1] * src[1][0]) / det;
+
+	return OK;
+}
+
+int calculate_calibration_values(float accel_ref[6][3], float accel_T[3][3], float accel_offs[3], float g) {
+	/* calculate offsets */
+	for (int i = 0; i < 3; i++) {
+		accel_offs[i] = (accel_ref[i * 2][i] + accel_ref[i * 2 + 1][i]) / 2;
+	}
+
+	/* fill matrix A for linear equations system*/
+	float mat_A[3][3];
+	memset(mat_A, 0, sizeof(mat_A));
+	for (int i = 0; i < 3; i++) {
+		for (int j = 0; j < 3; j++) {
+			float a = accel_ref[i * 2][j] - accel_offs[j];
+			mat_A[i][j] = a;
+		}
+	}
+
+	/* calculate inverse matrix for A */
+	float mat_A_inv[3][3];
+	if (mat_invert3(mat_A, mat_A_inv) != OK)
+		return ERROR;
+
+	/* copy results to accel_T */
+	for (int i = 0; i < 3; i++) {
+		for (int j = 0; j < 3; j++) {
+			/* simplify matrices mult because b has only one non-zero element == g at index i */
+			accel_T[j][i] = mat_A_inv[j][i] * g;
+		}
+	}
+
+	return OK;
+}
diff --git a/apps/commander/accelerometer_calibration.h b/apps/commander/accelerometer_calibration.h
new file mode 100644
index 000000000..c0169c2a1
--- /dev/null
+++ b/apps/commander/accelerometer_calibration.h
@@ -0,0 +1,16 @@
+/*
+ * accelerometer_calibration.h
+ *
+ *  Created on: 25.04.2013
+ *      Author: ton
+ */
+
+#ifndef ACCELEROMETER_CALIBRATION_H_
+#define ACCELEROMETER_CALIBRATION_H_
+
+#include <stdint.h>
+#include <uORB/topics/vehicle_status.h>
+
+void do_accel_calibration(int status_pub, struct vehicle_status_s *status, int mavlink_fd);
+
+#endif /* ACCELEROMETER_CALIBRATION_H_ */
diff --git a/apps/commander/commander.c b/apps/commander/commander.c
index 7c0a25f86..0f18d6cef 100644
--- a/apps/commander/commander.c
+++ b/apps/commander/commander.c
@@ -94,7 +94,7 @@
 #include <drivers/drv_baro.h>
 
 #include "calibration_routines.h"
-
+#include "accelerometer_calibration.h"
 
 PARAM_DEFINE_INT32(SYS_FAILSAVE_LL, 0);	/**< Go into low-level failsafe after 0 ms */
 //PARAM_DEFINE_INT32(SYS_FAILSAVE_HL, 0);	/**< Go into high-level failsafe after 0 ms */
@@ -158,7 +158,6 @@ static int led_off(int led);
 static void do_gyro_calibration(int status_pub, struct vehicle_status_s *status);
 static void do_mag_calibration(int status_pub, struct vehicle_status_s *status);
 static void do_rc_calibration(int status_pub, struct vehicle_status_s *status);
-static void do_accel_calibration(int status_pub, struct vehicle_status_s *status);
 static void handle_command(int status_pub, struct vehicle_status_s *current_status, struct vehicle_command_s *cmd);
 
 int trigger_audio_alarm(uint8_t old_mode, uint8_t old_state, uint8_t new_mode, uint8_t new_state);
@@ -666,126 +665,6 @@ void do_gyro_calibration(int status_pub, struct vehicle_status_s *status)
 	close(sub_sensor_combined);
 }
 
-void do_accel_calibration(int status_pub, struct vehicle_status_s *status)
-{
-	/* announce change */
-
-	mavlink_log_info(mavlink_fd, "keep it level and still");
-	/* set to accel calibration mode */
-	status->flag_preflight_accel_calibration = true;
-	state_machine_publish(status_pub, status, mavlink_fd);
-
-	const int calibration_count = 2500;
-
-	int sub_sensor_combined = orb_subscribe(ORB_ID(sensor_combined));
-	struct sensor_combined_s raw;
-
-	int calibration_counter = 0;
-	float accel_offset[3] = {0.0f, 0.0f, 0.0f};
-
-	int fd = open(ACCEL_DEVICE_PATH, 0);
-	struct accel_scale ascale_null = {
-		0.0f,
-		1.0f,
-		0.0f,
-		1.0f,
-		0.0f,
-		1.0f,
-	};
-
-	if (OK != ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&ascale_null))
-		warn("WARNING: failed to set scale / offsets for accel");
-
-	close(fd);
-
-	while (calibration_counter < calibration_count) {
-
-		/* wait blocking for new data */
-		struct pollfd fds[1] = { { .fd = sub_sensor_combined, .events = POLLIN } };
-
-		int poll_ret = poll(fds, 1, 1000);
-
-		if (poll_ret) {
-			orb_copy(ORB_ID(sensor_combined), sub_sensor_combined, &raw);
-			accel_offset[0] += raw.accelerometer_m_s2[0];
-			accel_offset[1] += raw.accelerometer_m_s2[1];
-			accel_offset[2] += raw.accelerometer_m_s2[2];
-			calibration_counter++;
-
-		} else if (poll_ret == 0) {
-			/* any poll failure for 1s is a reason to abort */
-			mavlink_log_info(mavlink_fd, "acceleration calibration aborted");
-			return;
-		}
-	}
-
-	accel_offset[0] = accel_offset[0] / calibration_count;
-	accel_offset[1] = accel_offset[1] / calibration_count;
-	accel_offset[2] = accel_offset[2] / calibration_count;
-
-	if (isfinite(accel_offset[0]) && isfinite(accel_offset[1]) && isfinite(accel_offset[2])) {
-
-		/* add the removed length from x / y to z, since we induce a scaling issue else */
-		float total_len = sqrtf(accel_offset[0] * accel_offset[0] + accel_offset[1] * accel_offset[1] + accel_offset[2] * accel_offset[2]);
-
-		/* if length is correct, zero results here */
-		accel_offset[2] = accel_offset[2] + total_len;
-
-		float scale = 9.80665f / total_len;
-
-		if (param_set(param_find("SENS_ACC_XOFF"), &(accel_offset[0]))
-			|| param_set(param_find("SENS_ACC_YOFF"), &(accel_offset[1]))
-			|| param_set(param_find("SENS_ACC_ZOFF"), &(accel_offset[2]))
-			|| param_set(param_find("SENS_ACC_XSCALE"), &(scale))
-			|| param_set(param_find("SENS_ACC_YSCALE"), &(scale))
-			|| param_set(param_find("SENS_ACC_ZSCALE"), &(scale))) {
-			mavlink_log_critical(mavlink_fd, "Setting offs or scale failed!");
-		}
-
-		fd = open(ACCEL_DEVICE_PATH, 0);
-		struct accel_scale ascale = {
-			accel_offset[0],
-			scale,
-			accel_offset[1],
-			scale,
-			accel_offset[2],
-			scale,
-		};
-
-		if (OK != ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&ascale))
-			warn("WARNING: failed to set scale / offsets for accel");
-
-		close(fd);
-
-		/* auto-save to EEPROM */
-		int save_ret = param_save_default();
-
-		if (save_ret != 0) {
-			warn("WARNING: auto-save of params to storage failed");
-		}
-
-		//char buf[50];
-		//sprintf(buf, "[cmd] accel cal: x:%8.4f y:%8.4f z:%8.4f\n", (double)accel_offset[0], (double)accel_offset[1], (double)accel_offset[2]);
-		//mavlink_log_info(mavlink_fd, buf);
-		mavlink_log_info(mavlink_fd, "accel calibration done");
-
-		tune_confirm();
-		sleep(2);
-		tune_confirm();
-		sleep(2);
-		/* third beep by cal end routine */
-
-	} else {
-		mavlink_log_info(mavlink_fd, "accel calibration FAILED (NaN)");
-	}
-
-	/* exit accel calibration mode */
-	status->flag_preflight_accel_calibration = false;
-	state_machine_publish(status_pub, status, mavlink_fd);
-
-	close(sub_sensor_combined);
-}
-
 void do_airspeed_calibration(int status_pub, struct vehicle_status_s *status)
 {
 	/* announce change */
@@ -1040,7 +919,7 @@ void handle_command(int status_pub, struct vehicle_status_s *current_vehicle_sta
 				if (current_status.state_machine == SYSTEM_STATE_PREFLIGHT) {
 					mavlink_log_info(mavlink_fd, "CMD starting accel cal");
 					tune_confirm();
-					do_accel_calibration(status_pub, &current_status);
+					do_accel_calibration(status_pub, &current_status, mavlink_fd);
 					tune_confirm();
 					mavlink_log_info(mavlink_fd, "CMD finished accel cal");
 					do_state_update(status_pub, &current_status, mavlink_fd, SYSTEM_STATE_STANDBY);