4 #include <hardware/sensors.h>
8 #include "calibration.h"
9 #include "matrix-ops.h"
13 #define MAX_RAW_DATA_COUNT 2000
14 static FILE *raw_data = NULL;
15 static FILE *raw_data_selected = NULL;
16 static FILE *compensation_data = NULL;
17 static int raw_data_count = 0;
21 static float select_points[DS_SIZE][3];
22 static int select_point_count = 0;
24 static int calibrated = 0;
25 static calibration_data cal_data;
27 /* reset calibration algorithm */
28 static void reset_calibration ()
31 select_point_count = 0;
32 for (i = 0; i < DS_SIZE; i++)
34 select_points[i][j] = 0;
37 static double calc_square_err (calibration_data data)
40 double raw[3][1], result[3][1], mat_diff[3][1];
43 for (i = 0; i < DS_SIZE; i++) {
44 raw[0][0] = select_points[i][0];
45 raw[1][0] = select_points[i][1];
46 raw[2][0] = select_points[i][2];
48 substract (3, 1, raw, data.offset, mat_diff);
49 multiply(3, 3, 1, data.w_invert, mat_diff, result);
51 double diff = sqrt(result[0][0] * result[0][0] + result[1][0] * result[1][0]
52 + result[2][0] * result[2][0]) - data.bfield;
60 // Given an real symmetric 3x3 matrix A, compute the eigenvalues
61 static void compute_eigenvalues(double mat[3][3], double* eig1, double* eig2, double* eig3)
63 double p = mat[0][1] * mat[0][1] + mat[0][2] * mat[0][2] + mat[1][2] * mat[1][2];
72 double q = (mat[0][0] + mat[1][1] + mat[2][2]) / 3;
73 double temp1 = mat[0][0] - q;
74 double temp2 = mat[1][1] - q;
75 double temp3 = mat[2][2] - q;
77 p = temp1 * temp1 + temp2 * temp2 + temp3 * temp3 + 2 * p;
81 assign(3, 3, mat, mat2);
85 multiply_scalar_inplace(3, 3, mat2, 1/p);
87 double r = (mat2[0][0] * mat2[1][1] * mat2[2][2] + mat2[0][1] * mat2[1][2] * mat2[2][0]
88 + mat2[0][2] * mat2[1][0] * mat2[2][1] - mat2[0][2] * mat2[1][1] * mat2[2][0]
89 - mat2[0][0] * mat2[1][2] * mat2[2][1] - mat2[0][1] * mat2[1][0] * mat2[2][2]) / 2;
99 *eig3 = q + 2 * p * cos(phi);
100 *eig1 = q + 2 * p * cos(phi + 2 * M_PI / 3);
101 *eig2 = 3 * q - *eig1 - *eig3;
104 static void calc_evector(double mat[3][3], double eig, double vec[3][1])
108 assign(3, 3, mat, h);
119 assign(2, 2, x_tmp, x);
121 double temp1 = x[0][0] * (-h[1][0]) + x[0][1] * (-h[2][0]);
122 double temp2 = x[1][0] * (-h[1][0]) + x[1][1] * (-h[2][0]);
123 double norm = sqrt(1 + temp1 * temp1 + temp2 * temp2);
125 vec[0][0] = 1.0 / norm;
126 vec[1][0] = temp1 / norm;
127 vec[2][0] = temp2 / norm;
130 static int ellipsoid_fit (mat_input_t m, double offset[3][1], double w_invert[3][3], double* bfield)
133 double h[DS_SIZE][9];
134 double w[DS_SIZE][1];
135 double h_trans[9][DS_SIZE];
136 double p_temp1[9][9];
137 double p_temp2[9][DS_SIZE];
138 double temp1[3][3], temp[3][3];
139 double temp1_inv[3][3];
143 double a[3][3], sqrt_evals[3][3], evecs[3][3], evecs_trans[3][3];
144 double evec1[3][1], evec2[3][1], evec3[3][1];
146 for (i = 0; i < DS_SIZE; i++) {
147 w[i][0] = m[i][0] * m[i][0];
151 h[i][3] = -1 * m[i][0] * m[i][1];
152 h[i][4] = -1 * m[i][0] * m[i][2];
153 h[i][5] = -1 * m[i][1] * m[i][2];
154 h[i][6] = -1 * m[i][1] * m[i][1];
155 h[i][7] = -1 * m[i][2] * m[i][2];
158 transpose (DS_SIZE, 9, h, h_trans);
159 multiply (9, DS_SIZE, 9, h_trans, h, result);
160 invert (9, result, p_temp1);
161 multiply (9, 9, DS_SIZE, p_temp1, h_trans, p_temp2);
162 multiply (9, DS_SIZE, 1, p_temp2, w, p);
165 temp1[0][1] = p[3][0];
166 temp1[0][2] = p[4][0];
167 temp1[1][0] = p[3][0];
168 temp1[1][1] = 2 * p[6][0];
169 temp1[1][2] = p[5][0];
170 temp1[2][0] = p[4][0];
171 temp1[2][1] = p[5][0];
172 temp1[2][2] = 2 * p[7][0];
174 temp2[0][0] = p[0][0];
175 temp2[1][0] = p[1][0];
176 temp2[2][0] = p[2][0];
178 invert(3, temp1, temp1_inv);
179 multiply(3, 3, 1, temp1_inv, temp2, offset);
180 double off_x = offset[0][0];
181 double off_y = offset[1][0];
182 double off_z = offset[2][0];
185 a[0][0] = 1.0 / (p[8][0] + off_x * off_x + p[6][0] * off_y * off_y
186 + p[7][0] * off_z * off_z + p[3][0] * off_x * off_y
187 + p[4][0] * off_x * off_z + p[5][0] * off_y * off_z);
189 a[0][1] = p[3][0] * a[0][0] / 2;
190 a[0][2] = p[4][0] * a[0][0] / 2;
191 a[1][2] = p[5][0] * a[0][0] / 2;
192 a[1][1] = p[6][0] * a[0][0];
193 a[2][2] = p[7][0] * a[0][0];
198 double eig1 = 0, eig2 = 0, eig3 = 0;
199 compute_eigenvalues(a, &eig1, &eig2, &eig3);
201 sqrt_evals[0][0] = sqrt(eig1);
202 sqrt_evals[1][0] = 0;
203 sqrt_evals[2][0] = 0;
204 sqrt_evals[0][1] = 0;
205 sqrt_evals[1][1] = sqrt(eig2);
206 sqrt_evals[2][1] = 0;
207 sqrt_evals[0][2] = 0;
208 sqrt_evals[1][2] = 0;
209 sqrt_evals[2][2] = sqrt(eig3);
211 calc_evector(a, eig1, evec1);
212 calc_evector(a, eig2, evec2);
213 calc_evector(a, eig3, evec3);
215 evecs[0][0] = evec1[0][0];
216 evecs[1][0] = evec1[1][0];
217 evecs[2][0] = evec1[2][0];
218 evecs[0][1] = evec2[0][0];
219 evecs[1][1] = evec2[1][0];
220 evecs[2][1] = evec2[2][0];
221 evecs[0][2] = evec3[0][0];
222 evecs[1][2] = evec3[1][0];
223 evecs[2][2] = evec3[2][0];
225 multiply (3, 3, 3, evecs, sqrt_evals, temp1);
226 transpose(3, 3, evecs, evecs_trans);
227 multiply (3, 3, 3, temp1, evecs_trans, temp);
228 transpose (3, 3, temp, w_invert);
229 *bfield = pow(sqrt(1/eig1) * sqrt(1/eig2) * sqrt(1/eig3), 1.0/3.0);
230 multiply_scalar_inplace(3, 3, w_invert, *bfield);
235 static void compass_cal_init (FILE* data_file)
244 if (raw_data_selected) {
245 fclose(raw_data_selected);
246 raw_data_selected = NULL;
250 snprintf(path, 64, RAW_DATA_FULL_PATH, file_no);
251 raw_data = fopen(path,"w+");
252 snprintf(path, 64, RAW_DATA_SELECTED_PATH, file_no);
253 raw_data_selected = fopen(path,"w+");
262 if (data_file != NULL) {
263 int ret = fscanf(data_file, "%d %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf %lf",
264 &calibrated, &cal_data.offset[0][0], &cal_data.offset[1][0], &cal_data.offset[2][0],
265 &cal_data.w_invert[0][0], &cal_data.w_invert[0][1], &cal_data.w_invert[0][2],
266 &cal_data.w_invert[1][0], &cal_data.w_invert[1][1], &cal_data.w_invert[1][2],
267 &cal_data.w_invert[2][0], &cal_data.w_invert[2][1], &cal_data.w_invert[2][2],
270 if (ret != data_count) {
276 ALOGI("CompassCalibration: load old data, caldata: %f %f %f %f %f %f %f %f %f %f %f %f %f",
277 cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0],
278 cal_data.w_invert[0][0], cal_data.w_invert[0][1],cal_data.w_invert[0][2],cal_data.w_invert[1][0],
279 cal_data.w_invert[1][1], cal_data.w_invert[1][2],cal_data.w_invert[2][0],cal_data.w_invert[2][1],
280 cal_data.w_invert[2][2], cal_data.bfield);
283 cal_data.offset[0][0] = 0;
284 cal_data.offset[1][0] = 0;
285 cal_data.offset[2][0] = 0;
287 cal_data.w_invert[0][0] = 1;
288 cal_data.w_invert[1][0] = 0;
289 cal_data.w_invert[2][0] = 0;
290 cal_data.w_invert[0][1] = 0;
291 cal_data.w_invert[1][1] = 1;
292 cal_data.w_invert[2][1] = 0;
293 cal_data.w_invert[0][2] = 0;
294 cal_data.w_invert[1][2] = 0;
295 cal_data.w_invert[2][2] = 1;
302 static void compass_store_result(FILE* data_file)
304 if (data_file == NULL)
306 int ret = fprintf(data_file, "%d %f %f %f %f %f %f %f %f %f %f %f %f %f\n",
307 calibrated, cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0],
308 cal_data.w_invert[0][0], cal_data.w_invert[0][1], cal_data.w_invert[0][2],
309 cal_data.w_invert[1][0], cal_data.w_invert[1][1], cal_data.w_invert[1][2],
310 cal_data.w_invert[2][0], cal_data.w_invert[2][1], cal_data.w_invert[2][2],
314 ALOGE ("compass calibration - store data failed!");
317 static int compass_collect (struct sensors_event_t* event, int64_t current_time)
319 float data[3] = {event->magnetic.x, event->magnetic.y, event->magnetic.z};
325 if (raw_data && raw_data_count < MAX_RAW_DATA_COUNT) {
326 fprintf(raw_data, "%f %f %f\n", (double)data[0], (double)data[1],
331 if (raw_data && raw_data_count >= MAX_RAW_DATA_COUNT) {
337 lookback_count = calibrated ? LOOKBACK_COUNT : FIRST_LOOKBACK_COUNT;
338 min_diff = calibrated ? MIN_DIFF : FIRST_MIN_DIFF;
340 // For the current point to be accepted, each x/y/z value must be different enough
341 // to the last several collected points
342 if (select_point_count > 0 && select_point_count < DS_SIZE) {
343 int lookback = lookback_count < select_point_count ? lookback_count : select_point_count;
344 for (index = 0; index < lookback; index++){
345 for (j = 0; j < 3; j++) {
346 if (fabsf(data[j] - select_points[select_point_count-1-index][j]) < min_diff) {
347 ALOGV("CompassCalibration:point reject: [%f,%f,%f], selected_count=%d",
348 data[0], data[1], data[2], select_point_count);
355 if (select_point_count < DS_SIZE) {
356 memcpy(select_points[select_point_count], data, sizeof(float) * 3);
357 select_point_count++;
358 ALOGV("CompassCalibration:point collected [%f,%f,%f], selected_count=%d",
359 (double)data[0], (double)data[1], (double)data[2], select_point_count);
361 if (raw_data_selected) {
362 fprintf(raw_data_selected, "%f %f %f\n", (double)data[0], (double)data[1], (double)data[2]);
369 static void compass_compute_cal (struct sensors_event_t* event)
374 double result[3][1], raw[3][1], diff[3][1];
376 raw[0][0] = event->magnetic.x;
377 raw[1][0] = event->magnetic.y;
378 raw[2][0] = event->magnetic.z;
380 substract(3, 1, raw, cal_data.offset, diff);
381 multiply (3, 3, 1, cal_data.w_invert, diff, result);
383 event->magnetic.x = event->data[0] = result[0][0];
384 event->magnetic.y = event->data[1] = result[1][0];
385 event->magnetic.z = event->data[2] = result[2][0];
388 static int compass_ready ()
394 if (select_point_count < DS_SIZE)
397 max_sqr_err = calibrated ? MAX_SQR_ERR : FIRST_MAX_SQR_ERR;
399 /* enough points have been collected, do the ellipsoid calibration */
400 for (i = 0; i < DS_SIZE; i++) {
401 mat[i][0] = select_points[i][0];
402 mat[i][1] = select_points[i][1];
403 mat[i][2] = select_points[i][2];
406 /* check if result is good */
407 calibration_data new_cal_data;
408 if (ellipsoid_fit(mat, new_cal_data.offset, new_cal_data.w_invert, &new_cal_data.bfield)) {
409 double new_err = calc_square_err (new_cal_data);
410 ALOGV("new err is %f, max sqr err id %f", new_err,max_sqr_err);
411 if (new_err < max_sqr_err) {
412 double err = calc_square_err(cal_data);
414 /* new cal data is better, so we switch to the new */
415 cal_data = new_cal_data;
417 ALOGV("CompassCalibration: ready check success, caldata: %f %f %f %f %f %f %f %f %f %f %f %f %f, err %f",
418 cal_data.offset[0][0], cal_data.offset[1][0], cal_data.offset[2][0], cal_data.w_invert[0][0],
419 cal_data.w_invert[0][1], cal_data.w_invert[0][2], cal_data.w_invert[1][0],cal_data.w_invert[1][1],
420 cal_data.w_invert[1][2], cal_data.w_invert[2][0], cal_data.w_invert[2][1], cal_data.w_invert[2][2],
421 cal_data.bfield, new_err);
429 void calibrate_compass (struct sensors_event_t* event, int64_t current_time)
431 long current_time_ms = current_time / 1000000;
432 compass_collect (event, current_time_ms);
433 if (compass_ready()) {
434 compass_compute_cal (event);
435 event->magnetic.status = SENSOR_STATUS_ACCURACY_HIGH;
437 event->magnetic.status = SENSOR_STATUS_ACCURACY_LOW;
441 void compass_read_data (const char* config_file)
443 FILE* data_file = fopen (config_file, "r");
445 compass_cal_init(data_file);
450 void compass_store_data (const char* config_file)
452 FILE* data_file = fopen (config_file, "w");
454 compass_store_result(data_file);