2 * Copyright (C) 2014 Intel Corporation.
8 #include <hardware/sensors.h>
11 #include <utils/Log.h>
12 #include "calibration.h"
13 #include "matrix-ops.h"
17 #define MAX_RAW_DATA_COUNT 2000
18 static FILE *raw_data = NULL;
19 static FILE *raw_data_selected = NULL;
20 static FILE *compensation_data = NULL;
21 static int raw_data_count = 0;
25 static float select_points[DS_SIZE][3];
26 static int select_point_count = 0;
28 static int calibrated = 0;
29 static calibration_data cal_data;
31 /* reset calibration algorithm */
32 static void reset_calibration ()
35 select_point_count = 0;
36 for (i = 0; i < DS_SIZE; i++)
38 select_points[i][j] = 0;
41 static double calc_square_err (calibration_data data)
44 double raw[3][1], result[3][1], mat_diff[3][1];
47 for (i = 0; i < DS_SIZE; i++) {
48 raw[0][0] = select_points[i][0];
49 raw[1][0] = select_points[i][1];
50 raw[2][0] = select_points[i][2];
52 substract (3, 1, raw, data.offset, mat_diff);
53 multiply(3, 3, 1, data.w_invert, mat_diff, result);
55 double diff = sqrt(result[0][0] * result[0][0] + result[1][0] * result[1][0]
56 + result[2][0] * result[2][0]) - data.bfield;
64 // Given an real symmetric 3x3 matrix A, compute the eigenvalues
65 static void compute_eigenvalues(double mat[3][3], double* eig1, double* eig2, double* eig3)
67 double p = mat[0][1] * mat[0][1] + mat[0][2] * mat[0][2] + mat[1][2] * mat[1][2];
76 double q = (mat[0][0] + mat[1][1] + mat[2][2]) / 3;
77 double temp1 = mat[0][0] - q;
78 double temp2 = mat[1][1] - q;
79 double temp3 = mat[2][2] - q;
81 p = temp1 * temp1 + temp2 * temp2 + temp3 * temp3 + 2 * p;
85 assign(3, 3, mat, mat2);
89 multiply_scalar_inplace(3, 3, mat2, 1/p);
91 double r = (mat2[0][0] * mat2[1][1] * mat2[2][2] + mat2[0][1] * mat2[1][2] * mat2[2][0]
92 + mat2[0][2] * mat2[1][0] * mat2[2][1] - mat2[0][2] * mat2[1][1] * mat2[2][0]
93 - mat2[0][0] * mat2[1][2] * mat2[2][1] - mat2[0][1] * mat2[1][0] * mat2[2][2]) / 2;
103 *eig3 = q + 2 * p * cos(phi);
104 *eig1 = q + 2 * p * cos(phi + 2 * M_PI / 3);
105 *eig2 = 3 * q - *eig1 - *eig3;
108 static void calc_evector(double mat[3][3], double eig, double vec[3][1])
112 assign(3, 3, mat, h);
123 assign(2, 2, x_tmp, x);
125 double temp1 = x[0][0] * (-h[1][0]) + x[0][1] * (-h[2][0]);
126 double temp2 = x[1][0] * (-h[1][0]) + x[1][1] * (-h[2][0]);
127 double norm = sqrt(1 + temp1 * temp1 + temp2 * temp2);
129 vec[0][0] = 1.0 / norm;
130 vec[1][0] = temp1 / norm;
131 vec[2][0] = temp2 / norm;
134 static int ellipsoid_fit (mat_input_t m, double offset[3][1], double w_invert[3][3], double* bfield)
137 double h[DS_SIZE][9];
138 double w[DS_SIZE][1];
139 double h_trans[9][DS_SIZE];
140 double p_temp1[9][9];
141 double p_temp2[9][DS_SIZE];
142 double temp1[3][3], temp[3][3];
143 double temp1_inv[3][3];
147 double a[3][3], sqrt_evals[3][3], evecs[3][3], evecs_trans[3][3];
148 double evec1[3][1], evec2[3][1], evec3[3][1];
150 for (i = 0; i < DS_SIZE; i++) {
151 w[i][0] = m[i][0] * m[i][0];
155 h[i][3] = -1 * m[i][0] * m[i][1];
156 h[i][4] = -1 * m[i][0] * m[i][2];
157 h[i][5] = -1 * m[i][1] * m[i][2];
158 h[i][6] = -1 * m[i][1] * m[i][1];
159 h[i][7] = -1 * m[i][2] * m[i][2];
162 transpose (DS_SIZE, 9, h, h_trans);
163 multiply (9, DS_SIZE, 9, h_trans, h, result);
164 invert (9, result, p_temp1);
165 multiply (9, 9, DS_SIZE, p_temp1, h_trans, p_temp2);
166 multiply (9, DS_SIZE, 1, p_temp2, w, p);
169 temp1[0][1] = p[3][0];
170 temp1[0][2] = p[4][0];
171 temp1[1][0] = p[3][0];
172 temp1[1][1] = 2 * p[6][0];
173 temp1[1][2] = p[5][0];
174 temp1[2][0] = p[4][0];
175 temp1[2][1] = p[5][0];
176 temp1[2][2] = 2 * p[7][0];
178 temp2[0][0] = p[0][0];
179 temp2[1][0] = p[1][0];
180 temp2[2][0] = p[2][0];
182 invert(3, temp1, temp1_inv);
183 multiply(3, 3, 1, temp1_inv, temp2, offset);
184 double off_x = offset[0][0];
185 double off_y = offset[1][0];
186 double off_z = offset[2][0];
189 a[0][0] = 1.0 / (p[8][0] + off_x * off_x + p[6][0] * off_y * off_y
190 + p[7][0] * off_z * off_z + p[3][0] * off_x * off_y
191 + p[4][0] * off_x * off_z + p[5][0] * off_y * off_z);
193 a[0][1] = p[3][0] * a[0][0] / 2;
194 a[0][2] = p[4][0] * a[0][0] / 2;
195 a[1][2] = p[5][0] * a[0][0] / 2;
196 a[1][1] = p[6][0] * a[0][0];
197 a[2][2] = p[7][0] * a[0][0];
202 double eig1 = 0, eig2 = 0, eig3 = 0;
203 compute_eigenvalues(a, &eig1, &eig2, &eig3);
205 sqrt_evals[0][0] = sqrt(eig1);
206 sqrt_evals[1][0] = 0;
207 sqrt_evals[2][0] = 0;
208 sqrt_evals[0][1] = 0;
209 sqrt_evals[1][1] = sqrt(eig2);
210 sqrt_evals[2][1] = 0;
211 sqrt_evals[0][2] = 0;
212 sqrt_evals[1][2] = 0;
213 sqrt_evals[2][2] = sqrt(eig3);
215 calc_evector(a, eig1, evec1);
216 calc_evector(a, eig2, evec2);
217 calc_evector(a, eig3, evec3);
219 evecs[0][0] = evec1[0][0];
220 evecs[1][0] = evec1[1][0];
221 evecs[2][0] = evec1[2][0];
222 evecs[0][1] = evec2[0][0];
223 evecs[1][1] = evec2[1][0];
224 evecs[2][1] = evec2[2][0];
225 evecs[0][2] = evec3[0][0];
226 evecs[1][2] = evec3[1][0];
227 evecs[2][2] = evec3[2][0];
229 multiply (3, 3, 3, evecs, sqrt_evals, temp1);
230 transpose(3, 3, evecs, evecs_trans);
231 multiply (3, 3, 3, temp1, evecs_trans, temp);
232 transpose (3, 3, temp, w_invert);
233 *bfield = pow(sqrt(1/eig1) * sqrt(1/eig2) * sqrt(1/eig3), 1.0/3.0);
234 multiply_scalar_inplace(3, 3, w_invert, *bfield);
239 static void compass_cal_init (FILE* data_file)
248 if (raw_data_selected) {
249 fclose(raw_data_selected);
250 raw_data_selected = NULL;
254 snprintf(path, 64, RAW_DATA_FULL_PATH, file_no);
255 raw_data = fopen(path,"w+");
256 snprintf(path, 64, RAW_DATA_SELECTED_PATH, file_no);
257 raw_data_selected = fopen(path,"w+");
266 if (data_file != NULL) {
267 int ret = fscanf(data_file, "%d %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf",
268 &calibrated, &cal_data.offset[0][0], &cal_data.offset[1][0], &cal_data.offset[2][0],
269 &cal_data.w_invert[0][0], &cal_data.w_invert[0][1], &cal_data.w_invert[0][2],
270 &cal_data.w_invert[1][0], &cal_data.w_invert[1][1], &cal_data.w_invert[1][2],
271 &cal_data.w_invert[2][0], &cal_data.w_invert[2][1], &cal_data.w_invert[2][2],
274 if (ret != data_count) {
280 ALOGI("CompassCalibration: load old data, caldata: %f %f %f %f %f %f %f %f %f %f %f %f %f",
281 cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0],
282 cal_data.w_invert[0][0], cal_data.w_invert[0][1],cal_data.w_invert[0][2],cal_data.w_invert[1][0],
283 cal_data.w_invert[1][1], cal_data.w_invert[1][2],cal_data.w_invert[2][0],cal_data.w_invert[2][1],
284 cal_data.w_invert[2][2], cal_data.bfield);
287 cal_data.offset[0][0] = 0;
288 cal_data.offset[1][0] = 0;
289 cal_data.offset[2][0] = 0;
291 cal_data.w_invert[0][0] = 1;
292 cal_data.w_invert[1][0] = 0;
293 cal_data.w_invert[2][0] = 0;
294 cal_data.w_invert[0][1] = 0;
295 cal_data.w_invert[1][1] = 1;
296 cal_data.w_invert[2][1] = 0;
297 cal_data.w_invert[0][2] = 0;
298 cal_data.w_invert[1][2] = 0;
299 cal_data.w_invert[2][2] = 1;
306 static void compass_store_result(FILE* data_file)
308 if (data_file == NULL)
310 int ret = fprintf(data_file, "%d %f %f %f %f %f %f %f %f %f %f %f %f %f\n",
311 calibrated, cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0],
312 cal_data.w_invert[0][0], cal_data.w_invert[0][1], cal_data.w_invert[0][2],
313 cal_data.w_invert[1][0], cal_data.w_invert[1][1], cal_data.w_invert[1][2],
314 cal_data.w_invert[2][0], cal_data.w_invert[2][1], cal_data.w_invert[2][2],
318 ALOGE ("compass calibration - store data failed!");
321 static int compass_collect (struct sensors_event_t* event, int64_t current_time)
323 float data[3] = {event->magnetic.x, event->magnetic.y, event->magnetic.z};
329 if (raw_data && raw_data_count < MAX_RAW_DATA_COUNT) {
330 fprintf(raw_data, "%f %f %f\n", (double)data[0], (double)data[1],
335 if (raw_data && raw_data_count >= MAX_RAW_DATA_COUNT) {
341 lookback_count = calibrated ? LOOKBACK_COUNT : FIRST_LOOKBACK_COUNT;
342 min_diff = calibrated ? MIN_DIFF : FIRST_MIN_DIFF;
344 // For the current point to be accepted, each x/y/z value must be different enough
345 // to the last several collected points
346 if (select_point_count > 0 && select_point_count < DS_SIZE) {
347 int lookback = lookback_count < select_point_count ? lookback_count : select_point_count;
348 for (index = 0; index < lookback; index++){
349 for (j = 0; j < 3; j++) {
350 if (fabsf(data[j] - select_points[select_point_count-1-index][j]) < min_diff) {
351 ALOGV("CompassCalibration:point reject: [%f,%f,%f], selected_count=%d",
352 data[0], data[1], data[2], select_point_count);
359 if (select_point_count < DS_SIZE) {
360 memcpy(select_points[select_point_count], data, sizeof(float) * 3);
361 select_point_count++;
362 ALOGV("CompassCalibration:point collected [%f,%f,%f], selected_count=%d",
363 (double)data[0], (double)data[1], (double)data[2], select_point_count);
365 if (raw_data_selected) {
366 fprintf(raw_data_selected, "%f %f %f\n", (double)data[0], (double)data[1], (double)data[2]);
373 static void compass_compute_cal (struct sensors_event_t* event)
378 double result[3][1], raw[3][1], diff[3][1];
380 raw[0][0] = event->magnetic.x;
381 raw[1][0] = event->magnetic.y;
382 raw[2][0] = event->magnetic.z;
384 substract(3, 1, raw, cal_data.offset, diff);
385 multiply (3, 3, 1, cal_data.w_invert, diff, result);
387 event->magnetic.x = event->data[0] = result[0][0];
388 event->magnetic.y = event->data[1] = result[1][0];
389 event->magnetic.z = event->data[2] = result[2][0];
392 static int compass_ready ()
398 if (select_point_count < DS_SIZE)
401 max_sqr_err = calibrated ? MAX_SQR_ERR : FIRST_MAX_SQR_ERR;
403 /* enough points have been collected, do the ellipsoid calibration */
404 for (i = 0; i < DS_SIZE; i++) {
405 mat[i][0] = select_points[i][0];
406 mat[i][1] = select_points[i][1];
407 mat[i][2] = select_points[i][2];
410 /* check if result is good */
411 calibration_data new_cal_data;
412 if (ellipsoid_fit(mat, new_cal_data.offset, new_cal_data.w_invert, &new_cal_data.bfield)) {
413 double new_err = calc_square_err (new_cal_data);
414 ALOGV("new err is %f, max sqr err id %f", new_err,max_sqr_err);
415 if (new_err < max_sqr_err) {
416 double err = calc_square_err(cal_data);
418 /* new cal data is better, so we switch to the new */
419 cal_data = new_cal_data;
421 ALOGV("CompassCalibration: ready check success, caldata: %f %f %f %f %f %f %f %f %f %f %f %f %f, err %f",
422 cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0], cal_data.w_invert[0][0],
423 cal_data.w_invert[0][1], cal_data.w_invert[0][2], cal_data.w_invert[1][0],cal_data.w_invert[1][1],
424 cal_data.w_invert[1][2], cal_data.w_invert[2][0], cal_data.w_invert[2][1], cal_data.w_invert[2][2],
425 cal_data.bfield, new_err);
433 void calibrate_compass (struct sensors_event_t* event, int64_t current_time)
435 long current_time_ms = current_time / 1000000;
436 compass_collect (event, current_time_ms);
437 if (compass_ready()) {
438 compass_compute_cal (event);
439 event->magnetic.status = SENSOR_STATUS_ACCURACY_HIGH;
441 event->magnetic.status = SENSOR_STATUS_ACCURACY_LOW;
445 void compass_read_data (const char* config_file)
447 FILE* data_file = fopen (config_file, "r");
449 compass_cal_init(data_file);
454 void compass_store_data (const char* config_file)
456 FILE* data_file = fopen (config_file, "w");
458 compass_store_result(data_file);