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diff --git a/src/modules/commander/accelerometer_calibration.cpp b/src/modules/commander/accelerometer_calibration.cpp
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+/****************************************************************************
+ *
+ * Copyright (C) 2013 PX4 Development Team. All rights reserved.
+ * Author: Anton Babushkin <anton.babushkin@me.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ * used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file accelerometer_calibration.cpp
+ *
+ * Implementation of accelerometer calibration.
+ *
+ * Transform acceleration vector to true orientation, scale and offset
+ *
+ * ===== 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
+ *
+ * @author Anton Babushkin <anton.babushkin@me.com>
+ */
+
+#include "accelerometer_calibration.h"
+#include "commander_helper.h"
+
+#include <unistd.h>
+#include <stdio.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <sys/prctl.h>
+#include <math.h>
+#include <string.h>
+#include <drivers/drv_hrt.h>
+#include <uORB/topics/sensor_combined.h>
+#include <drivers/drv_accel.h>
+#include <systemlib/conversions.h>
+#include <systemlib/param/param.h>
+#include <systemlib/err.h>
+#include <mavlink/mavlink_log.h>
+
+/* oddly, ERROR is not defined for c++ */
+#ifdef ERROR
+# undef ERROR
+#endif
+static const int ERROR = -1;
+
+int do_accel_calibration_measurements(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 mavlink_fd) {
+ /* announce change */
+ mavlink_log_info(mavlink_fd, "accel calibration started");
+
+ /* measure and calculate offsets & scales */
+ float accel_offs[3];
+ float accel_scale[3];
+ int res = do_accel_calibration_measurements(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_positive();
+ } else {
+ /* measurements error */
+ mavlink_log_info(mavlink_fd, "accel calibration aborted");
+ tune_negative();
+ }
+
+ /* exit accel calibration mode */
+}
+
+int do_accel_calibration_measurements(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],
+ (double)accel_ref[orient][0],
+ (double)accel_ref[orient][1],
+ (double)accel_ref[orient][2]);
+ mavlink_log_info(mavlink_fd, str);
+ data_collected[orient] = true;
+ tune_neutral();
+ }
+ 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 };
+ /* EMA time constant in seconds*/
+ float ema_len = 0.2f;
+ /* set "still" threshold to 0.25 m/s^2 */
+ float still_thr2 = pow(0.25f, 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];
+ fds[0].fd = sub_sensor_combined;
+ fds[0].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;
+
+ unsigned poll_errcount = 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) {
+ poll_errcount++;
+ }
+ if (t > t_timeout) {
+ poll_errcount++;
+ }
+
+ if (poll_errcount > 1000) {
+ mavlink_log_info(mavlink_fd, "ERROR: failed reading accel");
+ return -1;
+ }
+ }
+
+ if ( fabsf(accel_ema[0] - CONSTANTS_ONE_G) < accel_err_thr &&
+ fabsf(accel_ema[1]) < accel_err_thr &&
+ fabsf(accel_ema[2]) < accel_err_thr )
+ return 0; // [ g, 0, 0 ]
+ if ( fabsf(accel_ema[0] + CONSTANTS_ONE_G) < accel_err_thr &&
+ fabsf(accel_ema[1]) < accel_err_thr &&
+ fabsf(accel_ema[2]) < accel_err_thr )
+ return 1; // [ -g, 0, 0 ]
+ if ( fabsf(accel_ema[0]) < accel_err_thr &&
+ fabsf(accel_ema[1] - CONSTANTS_ONE_G) < accel_err_thr &&
+ fabsf(accel_ema[2]) < accel_err_thr )
+ return 2; // [ 0, g, 0 ]
+ if ( fabsf(accel_ema[0]) < accel_err_thr &&
+ fabsf(accel_ema[1] + CONSTANTS_ONE_G) < accel_err_thr &&
+ fabsf(accel_ema[2]) < accel_err_thr )
+ return 3; // [ 0, -g, 0 ]
+ if ( fabsf(accel_ema[0]) < accel_err_thr &&
+ fabsf(accel_ema[1]) < accel_err_thr &&
+ fabsf(accel_ema[2] - CONSTANTS_ONE_G) < accel_err_thr )
+ return 4; // [ 0, 0, g ]
+ if ( fabsf(accel_ema[0]) < accel_err_thr &&
+ fabsf(accel_ema[1]) < accel_err_thr &&
+ fabsf(accel_ema[2] + CONSTANTS_ONE_G) < 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];
+ fds[0].fd = sensor_combined_sub;
+ fds[0].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 == 0.0f)
+ 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;
+}
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