1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
|
/****************************************************************************
*
* Copyright (c) 2013 PX4 Development Team. All rights reserved.
*
* 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 attitude_estimator_so3_main.cpp
*
* @author Hyon Lim <limhyon@gmail.com>
* @author Anton Babushkin <anton.babushkin@me.com>
*
* Implementation of nonlinear complementary filters on the SO(3).
* This code performs attitude estimation by using accelerometer, gyroscopes and magnetometer.
* Result is provided as quaternion, 1-2-3 Euler angle and rotation matrix.
*
* Theory of nonlinear complementary filters on the SO(3) is based on [1].
* Quaternion realization of [1] is based on [2].
* Optmized quaternion update code is based on Sebastian Madgwick's implementation.
*
* References
* [1] Mahony, R.; Hamel, T.; Pflimlin, Jean-Michel, "Nonlinear Complementary Filters on the Special Orthogonal Group," Automatic Control, IEEE Transactions on , vol.53, no.5, pp.1203,1218, June 2008
* [2] Euston, M.; Coote, P.; Mahony, R.; Jonghyuk Kim; Hamel, T., "A complementary filter for attitude estimation of a fixed-wing UAV," Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on , vol., no., pp.340,345, 22-26 Sept. 2008
*/
#include <nuttx/config.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdbool.h>
#include <poll.h>
#include <fcntl.h>
#include <float.h>
#include <nuttx/sched.h>
#include <sys/prctl.h>
#include <termios.h>
#include <errno.h>
#include <limits.h>
#include <math.h>
#include <uORB/uORB.h>
#include <uORB/topics/debug_key_value.h>
#include <uORB/topics/sensor_combined.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/vehicle_control_mode.h>
#include <uORB/topics/parameter_update.h>
#include <drivers/drv_hrt.h>
#include <systemlib/systemlib.h>
#include <systemlib/perf_counter.h>
#include <systemlib/err.h>
#ifdef __cplusplus
extern "C" {
#endif
#include "attitude_estimator_so3_params.h"
#ifdef __cplusplus
}
#endif
extern "C" __EXPORT int attitude_estimator_so3_main(int argc, char *argv[]);
static bool thread_should_exit = false; /**< Deamon exit flag */
static bool thread_running = false; /**< Deamon status flag */
static int attitude_estimator_so3_task; /**< Handle of deamon task / thread */
//! Auxiliary variables to reduce number of repeated operations
static float q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f; /** quaternion of sensor frame relative to auxiliary frame */
static float dq0 = 0.0f, dq1 = 0.0f, dq2 = 0.0f, dq3 = 0.0f; /** quaternion of sensor frame relative to auxiliary frame */
static float gyro_bias[3] = {0.0f, 0.0f, 0.0f}; /** bias estimation */
static float q0q0, q0q1, q0q2, q0q3;
static float q1q1, q1q2, q1q3;
static float q2q2, q2q3;
static float q3q3;
static bool bFilterInit = false;
/**
* Mainloop of attitude_estimator_so3.
*/
int attitude_estimator_so3_thread_main(int argc, char *argv[]);
/**
* Print the correct usage.
*/
static void usage(const char *reason);
/* Function prototypes */
float invSqrt(float number);
void NonlinearSO3AHRSinit(float ax, float ay, float az, float mx, float my, float mz);
void NonlinearSO3AHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz, float twoKp, float twoKi, float dt);
static void
usage(const char *reason)
{
if (reason)
fprintf(stderr, "%s\n", reason);
fprintf(stderr, "usage: attitude_estimator_so3 {start|stop|status}\n");
exit(1);
}
/**
* The attitude_estimator_so3 app only briefly exists to start
* the background job. The stack size assigned in the
* Makefile does only apply to this management task.
*
* The actual stack size should be set in the call
* to task_spawn_cmd().
*/
int attitude_estimator_so3_main(int argc, char *argv[])
{
if (argc < 2) {
usage("missing command");
}
if (!strcmp(argv[1], "start")) {
if (thread_running) {
warnx("already running\n");
/* this is not an error */
exit(0);
}
thread_should_exit = false;
attitude_estimator_so3_task = task_spawn_cmd("attitude_estimator_so3",
SCHED_DEFAULT,
SCHED_PRIORITY_MAX - 5,
14000,
attitude_estimator_so3_thread_main,
(argv) ? (char * const *)&argv[2] : (char * const *)NULL);
exit(0);
}
if (!strcmp(argv[1], "stop")) {
thread_should_exit = true;
while (thread_running){
usleep(200000);
}
warnx("stopped");
exit(0);
}
if (!strcmp(argv[1], "status")) {
if (thread_running) {
warnx("running");
exit(0);
} else {
warnx("not started");
exit(1);
}
exit(0);
}
usage("unrecognized command");
exit(1);
}
//---------------------------------------------------------------------------------------------------
// Fast inverse square-root
// See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
float invSqrt(float number)
{
volatile long i;
volatile float x, y;
volatile const float f = 1.5F;
x = number * 0.5F;
y = number;
i = * (( long * ) &y);
i = 0x5f375a86 - ( i >> 1 );
y = * (( float * ) &i);
y = y * ( f - ( x * y * y ) );
return y;
}
//! Using accelerometer, sense the gravity vector.
//! Using magnetometer, sense yaw.
void NonlinearSO3AHRSinit(float ax, float ay, float az, float mx, float my, float mz)
{
float initialRoll, initialPitch;
float cosRoll, sinRoll, cosPitch, sinPitch;
float magX, magY;
float initialHdg, cosHeading, sinHeading;
initialRoll = atan2(-ay, -az);
initialPitch = atan2(ax, -az);
cosRoll = cosf(initialRoll);
sinRoll = sinf(initialRoll);
cosPitch = cosf(initialPitch);
sinPitch = sinf(initialPitch);
magX = mx * cosPitch + my * sinRoll * sinPitch + mz * cosRoll * sinPitch;
magY = my * cosRoll - mz * sinRoll;
initialHdg = atan2f(-magY, magX);
cosRoll = cosf(initialRoll * 0.5f);
sinRoll = sinf(initialRoll * 0.5f);
cosPitch = cosf(initialPitch * 0.5f);
sinPitch = sinf(initialPitch * 0.5f);
cosHeading = cosf(initialHdg * 0.5f);
sinHeading = sinf(initialHdg * 0.5f);
q0 = cosRoll * cosPitch * cosHeading + sinRoll * sinPitch * sinHeading;
q1 = sinRoll * cosPitch * cosHeading - cosRoll * sinPitch * sinHeading;
q2 = cosRoll * sinPitch * cosHeading + sinRoll * cosPitch * sinHeading;
q3 = cosRoll * cosPitch * sinHeading - sinRoll * sinPitch * cosHeading;
// auxillary variables to reduce number of repeated operations, for 1st pass
q0q0 = q0 * q0;
q0q1 = q0 * q1;
q0q2 = q0 * q2;
q0q3 = q0 * q3;
q1q1 = q1 * q1;
q1q2 = q1 * q2;
q1q3 = q1 * q3;
q2q2 = q2 * q2;
q2q3 = q2 * q3;
q3q3 = q3 * q3;
}
void NonlinearSO3AHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz, float twoKp, float twoKi, float dt)
{
float recipNorm;
float halfex = 0.0f, halfey = 0.0f, halfez = 0.0f;
// Make filter converge to initial solution faster
// This function assumes you are in static position.
// WARNING : in case air reboot, this can cause problem. But this is very unlikely happen.
if(bFilterInit == false) {
NonlinearSO3AHRSinit(ax,ay,az,mx,my,mz);
bFilterInit = true;
}
//! If magnetometer measurement is available, use it.
if(!((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f))) {
float hx, hy, hz, bx, bz;
float halfwx, halfwy, halfwz;
// Normalise magnetometer measurement
// Will sqrt work better? PX4 system is powerful enough?
recipNorm = invSqrt(mx * mx + my * my + mz * mz);
mx *= recipNorm;
my *= recipNorm;
mz *= recipNorm;
// Reference direction of Earth's magnetic field
hx = 2.0f * (mx * (0.5f - q2q2 - q3q3) + my * (q1q2 - q0q3) + mz * (q1q3 + q0q2));
hy = 2.0f * (mx * (q1q2 + q0q3) + my * (0.5f - q1q1 - q3q3) + mz * (q2q3 - q0q1));
hz = 2.0f * mx * (q1q3 - q0q2) + 2.0f * my * (q2q3 + q0q1) + 2.0f * mz * (0.5f - q1q1 - q2q2);
bx = sqrt(hx * hx + hy * hy);
bz = hz;
// Estimated direction of magnetic field
halfwx = bx * (0.5f - q2q2 - q3q3) + bz * (q1q3 - q0q2);
halfwy = bx * (q1q2 - q0q3) + bz * (q0q1 + q2q3);
halfwz = bx * (q0q2 + q1q3) + bz * (0.5f - q1q1 - q2q2);
// Error is sum of cross product between estimated direction and measured direction of field vectors
halfex += (my * halfwz - mz * halfwy);
halfey += (mz * halfwx - mx * halfwz);
halfez += (mx * halfwy - my * halfwx);
}
// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
float halfvx, halfvy, halfvz;
// Normalise accelerometer measurement
recipNorm = invSqrt(ax * ax + ay * ay + az * az);
ax *= recipNorm;
ay *= recipNorm;
az *= recipNorm;
// Estimated direction of gravity and magnetic field
halfvx = q1q3 - q0q2;
halfvy = q0q1 + q2q3;
halfvz = q0q0 - 0.5f + q3q3;
// Error is sum of cross product between estimated direction and measured direction of field vectors
halfex += ay * halfvz - az * halfvy;
halfey += az * halfvx - ax * halfvz;
halfez += ax * halfvy - ay * halfvx;
}
// Apply feedback only when valid data has been gathered from the accelerometer or magnetometer
if(halfex != 0.0f && halfey != 0.0f && halfez != 0.0f) {
// Compute and apply integral feedback if enabled
if(twoKi > 0.0f) {
gyro_bias[0] += twoKi * halfex * dt; // integral error scaled by Ki
gyro_bias[1] += twoKi * halfey * dt;
gyro_bias[2] += twoKi * halfez * dt;
// apply integral feedback
gx += gyro_bias[0];
gy += gyro_bias[1];
gz += gyro_bias[2];
}
else {
gyro_bias[0] = 0.0f; // prevent integral windup
gyro_bias[1] = 0.0f;
gyro_bias[2] = 0.0f;
}
// Apply proportional feedback
gx += twoKp * halfex;
gy += twoKp * halfey;
gz += twoKp * halfez;
}
//! Integrate rate of change of quaternion
#if 0
gx *= (0.5f * dt); // pre-multiply common factors
gy *= (0.5f * dt);
gz *= (0.5f * dt);
#endif
// Time derivative of quaternion. q_dot = 0.5*q\otimes omega.
//! q_k = q_{k-1} + dt*\dot{q}
//! \dot{q} = 0.5*q \otimes P(\omega)
dq0 = 0.5f*(-q1 * gx - q2 * gy - q3 * gz);
dq1 = 0.5f*(q0 * gx + q2 * gz - q3 * gy);
dq2 = 0.5f*(q0 * gy - q1 * gz + q3 * gx);
dq3 = 0.5f*(q0 * gz + q1 * gy - q2 * gx);
q0 += dt*dq0;
q1 += dt*dq1;
q2 += dt*dq2;
q3 += dt*dq3;
// Normalise quaternion
recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
q0 *= recipNorm;
q1 *= recipNorm;
q2 *= recipNorm;
q3 *= recipNorm;
// Auxiliary variables to avoid repeated arithmetic
q0q0 = q0 * q0;
q0q1 = q0 * q1;
q0q2 = q0 * q2;
q0q3 = q0 * q3;
q1q1 = q1 * q1;
q1q2 = q1 * q2;
q1q3 = q1 * q3;
q2q2 = q2 * q2;
q2q3 = q2 * q3;
q3q3 = q3 * q3;
}
/*
* Nonliner complementary filter on SO(3), attitude estimator main function.
*
* Estimates the attitude once started.
*
* @param argc number of commandline arguments (plus command name)
* @param argv strings containing the arguments
*/
int attitude_estimator_so3_thread_main(int argc, char *argv[])
{
//! Time constant
float dt = 0.005f;
/* output euler angles */
float euler[3] = {0.0f, 0.0f, 0.0f};
/* Initialization */
float Rot_matrix[9] = {1.f, 0.0f, 0.0f, 0.0f, 1.f, 0.0f, 0.0f, 0.0f, 1.f }; /**< init: identity matrix */
float acc[3] = {0.0f, 0.0f, 0.0f};
float gyro[3] = {0.0f, 0.0f, 0.0f};
float mag[3] = {0.0f, 0.0f, 0.0f};
warnx("main thread started");
struct sensor_combined_s raw;
memset(&raw, 0, sizeof(raw));
//! Initialize attitude vehicle uORB message.
struct vehicle_attitude_s att;
memset(&att, 0, sizeof(att));
struct vehicle_control_mode_s control_mode;
memset(&control_mode, 0, sizeof(control_mode));
uint64_t last_data = 0;
uint64_t last_measurement = 0;
/* subscribe to raw data */
int sub_raw = orb_subscribe(ORB_ID(sensor_combined));
/* rate-limit raw data updates to 333 Hz (sensors app publishes at 200, so this is just paranoid) */
orb_set_interval(sub_raw, 3);
/* subscribe to param changes */
int sub_params = orb_subscribe(ORB_ID(parameter_update));
/* subscribe to control mode */
int sub_control_mode = orb_subscribe(ORB_ID(vehicle_control_mode));
/* advertise attitude */
//orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
//orb_advert_t att_pub = -1;
orb_advert_t att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);
int loopcounter = 0;
thread_running = true;
// XXX write this out to perf regs
/* keep track of sensor updates */
uint64_t sensor_last_timestamp[3] = {0, 0, 0};
struct attitude_estimator_so3_params so3_comp_params;
struct attitude_estimator_so3_param_handles so3_comp_param_handles;
/* initialize parameter handles */
parameters_init(&so3_comp_param_handles);
parameters_update(&so3_comp_param_handles, &so3_comp_params);
uint64_t start_time = hrt_absolute_time();
bool initialized = false;
bool state_initialized = false;
float gyro_offsets[3] = { 0.0f, 0.0f, 0.0f };
unsigned offset_count = 0;
/* register the perf counter */
perf_counter_t so3_comp_loop_perf = perf_alloc(PC_ELAPSED, "attitude_estimator_so3");
/* Main loop*/
while (!thread_should_exit) {
struct pollfd fds[2];
fds[0].fd = sub_raw;
fds[0].events = POLLIN;
fds[1].fd = sub_params;
fds[1].events = POLLIN;
int ret = poll(fds, 2, 1000);
if (ret < 0) {
/* XXX this is seriously bad - should be an emergency */
} else if (ret == 0) {
/* check if we're in HIL - not getting sensor data is fine then */
orb_copy(ORB_ID(vehicle_control_mode), sub_control_mode, &control_mode);
if (!control_mode.flag_system_hil_enabled) {
warnx("WARNING: Not getting sensors - sensor app running?");
}
} else {
/* only update parameters if they changed */
if (fds[1].revents & POLLIN) {
/* read from param to clear updated flag */
struct parameter_update_s update;
orb_copy(ORB_ID(parameter_update), sub_params, &update);
/* update parameters */
parameters_update(&so3_comp_param_handles, &so3_comp_params);
}
/* only run filter if sensor values changed */
if (fds[0].revents & POLLIN) {
/* get latest measurements */
orb_copy(ORB_ID(sensor_combined), sub_raw, &raw);
if (!initialized) {
gyro_offsets[0] += raw.gyro_rad_s[0];
gyro_offsets[1] += raw.gyro_rad_s[1];
gyro_offsets[2] += raw.gyro_rad_s[2];
offset_count++;
if (hrt_absolute_time() > start_time + 3000000l) {
initialized = true;
gyro_offsets[0] /= offset_count;
gyro_offsets[1] /= offset_count;
gyro_offsets[2] /= offset_count;
warnx("gyro initialized, offsets: %.5f %.5f %.5f", (double)gyro_offsets[0], (double)gyro_offsets[1], (double)gyro_offsets[2]);
}
} else {
perf_begin(so3_comp_loop_perf);
/* Calculate data time difference in seconds */
dt = (raw.timestamp - last_measurement) / 1000000.0f;
last_measurement = raw.timestamp;
/* Fill in gyro measurements */
if (sensor_last_timestamp[0] != raw.timestamp) {
sensor_last_timestamp[0] = raw.timestamp;
}
gyro[0] = raw.gyro_rad_s[0] - gyro_offsets[0];
gyro[1] = raw.gyro_rad_s[1] - gyro_offsets[1];
gyro[2] = raw.gyro_rad_s[2] - gyro_offsets[2];
/* update accelerometer measurements */
if (sensor_last_timestamp[1] != raw.accelerometer_timestamp) {
sensor_last_timestamp[1] = raw.accelerometer_timestamp;
}
acc[0] = raw.accelerometer_m_s2[0];
acc[1] = raw.accelerometer_m_s2[1];
acc[2] = raw.accelerometer_m_s2[2];
/* update magnetometer measurements */
if (sensor_last_timestamp[2] != raw.magnetometer_timestamp) {
sensor_last_timestamp[2] = raw.magnetometer_timestamp;
}
mag[0] = raw.magnetometer_ga[0];
mag[1] = raw.magnetometer_ga[1];
mag[2] = raw.magnetometer_ga[2];
/* initialize with good values once we have a reasonable dt estimate */
if (!state_initialized && dt < 0.05f && dt > 0.001f) {
state_initialized = true;
warnx("state initialized");
}
/* do not execute the filter if not initialized */
if (!state_initialized) {
continue;
}
// NOTE : Accelerometer is reversed.
// Because proper mount of PX4 will give you a reversed accelerometer readings.
NonlinearSO3AHRSupdate(gyro[0], gyro[1], gyro[2],
-acc[0], -acc[1], -acc[2],
mag[0], mag[1], mag[2],
so3_comp_params.Kp,
so3_comp_params.Ki,
dt);
// Convert q->R, This R converts inertial frame to body frame.
Rot_matrix[0] = q0q0 + q1q1 - q2q2 - q3q3;// 11
Rot_matrix[1] = 2.f * (q1*q2 + q0*q3); // 12
Rot_matrix[2] = 2.f * (q1*q3 - q0*q2); // 13
Rot_matrix[3] = 2.f * (q1*q2 - q0*q3); // 21
Rot_matrix[4] = q0q0 - q1q1 + q2q2 - q3q3;// 22
Rot_matrix[5] = 2.f * (q2*q3 + q0*q1); // 23
Rot_matrix[6] = 2.f * (q1*q3 + q0*q2); // 31
Rot_matrix[7] = 2.f * (q2*q3 - q0*q1); // 32
Rot_matrix[8] = q0q0 - q1q1 - q2q2 + q3q3;// 33
//1-2-3 Representation.
//Equation (290)
//Representing Attitude: Euler Angles, Unit Quaternions, and Rotation Vectors, James Diebel.
// Existing PX4 EKF code was generated by MATLAB which uses coloum major order matrix.
euler[0] = atan2f(Rot_matrix[5], Rot_matrix[8]); //! Roll
euler[1] = -asinf(Rot_matrix[2]); //! Pitch
euler[2] = atan2f(Rot_matrix[1], Rot_matrix[0]); //! Yaw
/* swap values for next iteration, check for fatal inputs */
if (isfinite(euler[0]) && isfinite(euler[1]) && isfinite(euler[2])) {
// Publish only finite euler angles
att.roll = euler[0] - so3_comp_params.roll_off;
att.pitch = euler[1] - so3_comp_params.pitch_off;
att.yaw = euler[2] - so3_comp_params.yaw_off;
} else {
/* due to inputs or numerical failure the output is invalid, skip it */
// Due to inputs or numerical failure the output is invalid
warnx("infinite euler angles, rotation matrix:");
warnx("%.3f %.3f %.3f", (double)Rot_matrix[0], (double)Rot_matrix[1], (double)Rot_matrix[2]);
warnx("%.3f %.3f %.3f", (double)Rot_matrix[3], (double)Rot_matrix[4], (double)Rot_matrix[5]);
warnx("%.3f %.3f %.3f", (double)Rot_matrix[6], (double)Rot_matrix[7], (double)Rot_matrix[8]);
// Don't publish anything
continue;
}
if (last_data > 0 && raw.timestamp > last_data + 12000) {
warnx("sensor data missed");
}
last_data = raw.timestamp;
/* send out */
att.timestamp = raw.timestamp;
// Quaternion
att.q[0] = q0;
att.q[1] = q1;
att.q[2] = q2;
att.q[3] = q3;
att.q_valid = true;
// Euler angle rate. But it needs to be investigated again.
/*
att.rollspeed = 2.0f*(-q1*dq0 + q0*dq1 - q3*dq2 + q2*dq3);
att.pitchspeed = 2.0f*(-q2*dq0 + q3*dq1 + q0*dq2 - q1*dq3);
att.yawspeed = 2.0f*(-q3*dq0 -q2*dq1 + q1*dq2 + q0*dq3);
*/
att.rollspeed = gyro[0];
att.pitchspeed = gyro[1];
att.yawspeed = gyro[2];
att.rollacc = 0;
att.pitchacc = 0;
att.yawacc = 0;
/* TODO: Bias estimation required */
memcpy(&att.rate_offsets, &(gyro_bias), sizeof(att.rate_offsets));
/* copy rotation matrix */
memcpy(&att.R, Rot_matrix, sizeof(float)*9);
att.R_valid = true;
// Publish
if (att_pub > 0) {
orb_publish(ORB_ID(vehicle_attitude), att_pub, &att);
} else {
warnx("NaN in roll/pitch/yaw estimate!");
orb_advertise(ORB_ID(vehicle_attitude), &att);
}
perf_end(so3_comp_loop_perf);
}
}
}
loopcounter++;
}
thread_running = false;
return 0;
}
|