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/**
* @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 side 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
*
* ===== Rotation =====
*
* Calibrating using model:
* accel_corr = accel_T_r * (rot * accel_raw - accel_offs_r)
*
* Actual correction:
* accel_corr = rot * accel_T * (accel_raw - accel_offs)
*
* Known: accel_T_r, accel_offs_r, rot
* Unknown: accel_T, accel_offs
*
* Solution:
* accel_T_r * (rot * accel_raw - accel_offs_r) = rot * accel_T * (accel_raw - accel_offs)
* rot^-1 * accel_T_r * (rot * accel_raw - accel_offs_r) = accel_T * (accel_raw - accel_offs)
* rot^-1 * accel_T_r * rot * accel_raw - rot^-1 * accel_T_r * accel_offs_r = accel_T * accel_raw - accel_T * accel_offs)
* => accel_T = rot^-1 * accel_T_r * rot
* => accel_offs = rot^-1 * accel_offs_r
*
* @author Anton Babushkin <anton.babushkin@me.com>
*/
// FIXME: Can some of these headers move out with detect_ move?
#include "accelerometer_calibration.h"
#include "calibration_messages.h"
#include "calibration_routines.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 <float.h>
#include <mathlib/mathlib.h>
#include <string.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_accel.h>
#include <geo/geo.h>
#include <conversion/rotation.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;
static const char *sensor_name = "accel";
int do_accel_calibration_measurements(int mavlink_fd, float (&accel_offs)[max_accel_sens][3], float (&accel_T)[max_accel_sens][3][3], unsigned *active_sensors);
int read_accelerometer_avg(int (&subs)[max_accel_sens], float (&accel_avg)[max_accel_sens][detect_orientation_side_count][3], unsigned orient, unsigned samples_num);
int mat_invert3(float src[3][3], float dst[3][3]);
int calculate_calibration_values(unsigned sensor, float (&accel_ref)[max_accel_sens][detect_orientation_side_count][3], float (&accel_T)[max_accel_sens][3][3], float (&accel_offs)[max_accel_sens][3], float g);
int accel_calibration_worker(detect_orientation_return orientation, void* worker_data);
/// Data passed to calibration worker routine
typedef struct {
int mavlink_fd;
unsigned done_count;
int subs[max_accel_sens];
float accel_ref[max_accel_sens][detect_orientation_side_count][3];
} accel_worker_data_t;
int do_accel_calibration(int mavlink_fd)
{
int fd;
int32_t device_id[max_accel_sens];
mavlink_and_console_log_info(mavlink_fd, CAL_STARTED_MSG, sensor_name);
struct accel_scale accel_scale = {
0.0f,
1.0f,
0.0f,
1.0f,
0.0f,
1.0f,
};
int res = OK;
char str[30];
/* reset all sensors */
for (unsigned s = 0; s < max_accel_sens; s++) {
sprintf(str, "%s%u", ACCEL_BASE_DEVICE_PATH, s);
/* reset all offsets to zero and all scales to one */
fd = open(str, 0);
if (fd < 0) {
continue;
}
device_id[s] = ioctl(fd, DEVIOCGDEVICEID, 0);
res = ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&accel_scale);
close(fd);
if (res != OK) {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_RESET_CAL_MSG, s);
}
}
float accel_offs[max_accel_sens][3];
float accel_T[max_accel_sens][3][3];
unsigned active_sensors;
if (res == OK) {
/* measure and calculate offsets & scales */
res = do_accel_calibration_measurements(mavlink_fd, accel_offs, accel_T, &active_sensors);
}
if (res != OK || active_sensors == 0) {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_SENSOR_MSG);
return ERROR;
}
/* measurements completed successfully, rotate calibration values */
param_t board_rotation_h = param_find("SENS_BOARD_ROT");
int32_t board_rotation_int;
param_get(board_rotation_h, &(board_rotation_int));
enum Rotation board_rotation_id = (enum Rotation)board_rotation_int;
math::Matrix<3, 3> board_rotation;
get_rot_matrix(board_rotation_id, &board_rotation);
math::Matrix<3, 3> board_rotation_t = board_rotation.transposed();
for (unsigned i = 0; i < active_sensors; i++) {
/* handle individual sensors, one by one */
math::Vector<3> accel_offs_vec(accel_offs[i]);
math::Vector<3> accel_offs_rotated = board_rotation_t * accel_offs_vec;
math::Matrix<3, 3> accel_T_mat(accel_T[i]);
math::Matrix<3, 3> accel_T_rotated = board_rotation_t * accel_T_mat * board_rotation;
accel_scale.x_offset = accel_offs_rotated(0);
accel_scale.x_scale = accel_T_rotated(0, 0);
accel_scale.y_offset = accel_offs_rotated(1);
accel_scale.y_scale = accel_T_rotated(1, 1);
accel_scale.z_offset = accel_offs_rotated(2);
accel_scale.z_scale = accel_T_rotated(2, 2);
bool failed = false;
/* set parameters */
(void)sprintf(str, "CAL_ACC%u_XOFF", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.x_offset)));
(void)sprintf(str, "CAL_ACC%u_YOFF", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.y_offset)));
(void)sprintf(str, "CAL_ACC%u_ZOFF", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.z_offset)));
(void)sprintf(str, "CAL_ACC%u_XSCALE", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.x_scale)));
(void)sprintf(str, "CAL_ACC%u_YSCALE", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.y_scale)));
(void)sprintf(str, "CAL_ACC%u_ZSCALE", i);
failed |= (OK != param_set_no_notification(param_find(str), &(accel_scale.z_scale)));
(void)sprintf(str, "CAL_ACC%u_ID", i);
failed |= (OK != param_set_no_notification(param_find(str), &(device_id[i])));
if (failed) {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_SET_PARAMS_MSG, i);
return ERROR;
}
sprintf(str, "%s%u", ACCEL_BASE_DEVICE_PATH, i);
fd = open(str, 0);
if (fd < 0) {
mavlink_and_console_log_critical(mavlink_fd, "sensor does not exist");
res = ERROR;
} else {
res = ioctl(fd, ACCELIOCSSCALE, (long unsigned int)&accel_scale);
close(fd);
}
if (res != OK) {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_APPLY_CAL_MSG, i);
}
}
if (res == OK) {
/* auto-save to EEPROM */
res = param_save_default();
if (res != OK) {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_SAVE_PARAMS_MSG);
}
mavlink_and_console_log_info(mavlink_fd, CAL_DONE_MSG, sensor_name);
} else {
mavlink_and_console_log_critical(mavlink_fd, CAL_FAILED_MSG, sensor_name);
}
return res;
}
int accel_calibration_worker(detect_orientation_return orientation, void* data)
{
const unsigned samples_num = 3000;
accel_worker_data_t* worker_data = (accel_worker_data_t*)(data);
mavlink_and_console_log_info(worker_data->mavlink_fd, "Hold still, starting to measure %s side", detect_orientation_str(orientation));
read_accelerometer_avg(worker_data->subs, worker_data->accel_ref, orientation, samples_num);
mavlink_and_console_log_info(worker_data->mavlink_fd, "%s side result: [ %8.4f %8.4f %8.4f ]", detect_orientation_str(orientation),
(double)worker_data->accel_ref[0][orientation][0],
(double)worker_data->accel_ref[0][orientation][1],
(double)worker_data->accel_ref[0][orientation][2]);
worker_data->done_count++;
mavlink_and_console_log_info(worker_data->mavlink_fd, CAL_PROGRESS_MSG, sensor_name, 17 * worker_data->done_count);
return OK;
}
int do_accel_calibration_measurements(int mavlink_fd, float (&accel_offs)[max_accel_sens][3], float (&accel_T)[max_accel_sens][3][3], unsigned *active_sensors)
{
int result = OK;
*active_sensors = 0;
accel_worker_data_t worker_data;
worker_data.mavlink_fd = mavlink_fd;
worker_data.done_count = 0;
bool data_collected[detect_orientation_side_count] = { false, false, false, false, false, false };
// Initialize subs to error condition so we know which ones are open and which are not
for (size_t i=0; i<max_accel_sens; i++) {
worker_data.subs[i] = -1;
}
uint64_t timestamps[max_accel_sens];
for (unsigned i = 0; i < max_accel_sens; i++) {
worker_data.subs[i] = orb_subscribe_multi(ORB_ID(sensor_accel), i);
if (worker_data.subs[i] < 0) {
result = ERROR;
break;
}
/* store initial timestamp - used to infer which sensors are active */
struct accel_report arp = {};
(void)orb_copy(ORB_ID(sensor_accel), worker_data.subs[i], &arp);
timestamps[i] = arp.timestamp;
}
if (result == OK) {
result = calibrate_from_orientation(mavlink_fd, data_collected, accel_calibration_worker, &worker_data);
}
/* close all subscriptions */
for (unsigned i = 0; i < max_accel_sens; i++) {
if (worker_data.subs[i] >= 0) {
/* figure out which sensors were active */
struct accel_report arp = {};
(void)orb_copy(ORB_ID(sensor_accel), worker_data.subs[i], &arp);
if (arp.timestamp != 0 && timestamps[i] != arp.timestamp) {
(*active_sensors)++;
}
close(worker_data.subs[i]);
}
}
if (result == OK) {
/* calculate offsets and transform matrix */
for (unsigned i = 0; i < (*active_sensors); i++) {
result = calculate_calibration_values(i, worker_data.accel_ref, accel_T, accel_offs, CONSTANTS_ONE_G);
if (result != OK) {
mavlink_and_console_log_critical(mavlink_fd, "ERROR: calibration values calculation error");
break;
}
}
}
return result;
}
/*
* Read specified number of accelerometer samples, calculate average and dispersion.
*/
int read_accelerometer_avg(int (&subs)[max_accel_sens], float (&accel_avg)[max_accel_sens][detect_orientation_side_count][3], unsigned orient, unsigned samples_num)
{
struct pollfd fds[max_accel_sens];
for (unsigned i = 0; i < max_accel_sens; i++) {
fds[i].fd = subs[i];
fds[i].events = POLLIN;
}
unsigned counts[max_accel_sens] = { 0 };
float accel_sum[max_accel_sens][3];
memset(accel_sum, 0, sizeof(accel_sum));
unsigned errcount = 0;
/* use the first sensor to pace the readout, but do per-sensor counts */
while (counts[0] < samples_num) {
int poll_ret = poll(&fds[0], max_accel_sens, 1000);
if (poll_ret > 0) {
for (unsigned s = 0; s < max_accel_sens; s++) {
bool changed;
orb_check(subs[s], &changed);
if (changed) {
struct accel_report arp;
orb_copy(ORB_ID(sensor_accel), subs[s], &arp);
accel_sum[s][0] += arp.x;
accel_sum[s][1] += arp.y;
accel_sum[s][2] += arp.z;
counts[s]++;
}
}
} else {
errcount++;
continue;
}
if (errcount > samples_num / 10) {
return ERROR;
}
}
for (unsigned s = 0; s < max_accel_sens; s++) {
for (unsigned i = 0; i < 3; i++) {
accel_avg[s][orient][i] = accel_sum[s][i] / counts[s];
}
}
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 (fabsf(det) < FLT_EPSILON) {
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(unsigned sensor, float (&accel_ref)[max_accel_sens][detect_orientation_side_count][3], float (&accel_T)[max_accel_sens][3][3], float (&accel_offs)[max_accel_sens][3], float g)
{
/* calculate offsets */
for (unsigned i = 0; i < 3; i++) {
accel_offs[sensor][i] = (accel_ref[sensor][i * 2][i] + accel_ref[sensor][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 (unsigned i = 0; i < 3; i++) {
for (unsigned j = 0; j < 3; j++) {
float a = accel_ref[sensor][i * 2][j] - accel_offs[sensor][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 (unsigned i = 0; i < 3; i++) {
for (unsigned j = 0; j < 3; j++) {
/* simplify matrices mult because b has only one non-zero element == g at index i */
accel_T[sensor][j][i] = mat_A_inv[j][i] * g;
}
}
return OK;
}