path: root/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_main.cpp

/*
 * @file attitude_estimator_so3_comp_main.c
 *
 * Nonlinear SO3 filter for Attitude Estimation.
 */

#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_status.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_comp_params.h"
#ifdef __cplusplus
}
#endif

extern "C" __EXPORT int attitude_estimator_so3_comp_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_comp_task;				/**< Handle of deamon task / thread */
static float q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f;					// quaternion of sensor frame relative to auxiliary frame
static float integralFBx = 0.0f,  integralFBy = 0.0f, integralFBz = 0.0f;	// integral error terms scaled by Ki

/**
 * Mainloop of attitude_estimator_so3_comp.
 */
int attitude_estimator_so3_comp_thread_main(int argc, char *argv[]);

/**
 * Print the correct usage.
 */
static void usage(const char *reason);

static void
usage(const char *reason)
{
	if (reason)
		fprintf(stderr, "%s\n", reason);

	fprintf(stderr, "usage: attitude_estimator_so3_comp {start|stop|status} [-p <additional params>]\n\n");
	exit(1);
}

/**
 * The attitude_estimator_so3_comp 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_create().
 */
int attitude_estimator_so3_comp_main(int argc, char *argv[])
{
	if (argc < 1)
		usage("missing command");

	if (!strcmp(argv[1], "start")) {

		if (thread_running) {
			printf("attitude_estimator_so3_comp already running\n");
			/* this is not an error */
			exit(0);
		}

		thread_should_exit = false;
		attitude_estimator_so3_comp_task = task_spawn("attitude_estimator_so3_comp",
					      SCHED_DEFAULT,
					      SCHED_PRIORITY_MAX - 5,
					      12400,
					      attitude_estimator_so3_comp_thread_main,
					      (argv) ? (const char **)&argv[2] : (const char **)NULL);
		exit(0);
	}

	if (!strcmp(argv[1], "stop")) {
		thread_should_exit = true;
		exit(0);
	}

	if (!strcmp(argv[1], "status")) {
		if (thread_running) {
			printf("\tattitude_estimator_so3_comp app is running\n");

		} else {
			printf("\tattitude_estimator_so3_comp app not started\n");
		}

		exit(0);
	}

	usage("unrecognized command");
	exit(1);
}

//---------------------------------------------------------------------------------------------------
// Fast inverse square-root
// See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
float invSqrt(float x) {
	float halfx = 0.5f * x;
	float y = x;
	long i = *(long*)&y;
	i = 0x5f3759df - (i>>1);
	y = *(float*)&i;
	y = y * (1.5f - (halfx * y * y));
	return y;
}

void MahonyAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, float az, float twoKp, float twoKi, float dt) {
	float recipNorm;
	float halfvx, halfvy, halfvz;
	float halfex, halfey, halfez;

	// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
	if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

		// Normalise accelerometer measurement
		recipNorm = invSqrt(ax * ax + ay * ay + az * az);
		ax *= recipNorm;
		ay *= recipNorm;
		az *= recipNorm;        

		// Estimated direction of gravity and vector perpendicular to magnetic flux
		halfvx = q1 * q3 - q0 * q2;
		halfvy = q0 * q1 + q2 * q3;
		halfvz = q0 * q0 - 0.5f + q3 * q3;
	
		// Error is sum of cross product between estimated and measured direction of gravity
		halfex = (ay * halfvz - az * halfvy);
		halfey = (az * halfvx - ax * halfvz);
		halfez = (ax * halfvy - ay * halfvx);

		// Compute and apply integral feedback if enabled
		if(twoKi > 0.0f) {
			integralFBx += twoKi * halfex * dt;	// integral error scaled by Ki
			integralFBy += twoKi * halfey * dt;
			integralFBz += twoKi * halfez * dt;
			gx += integralFBx;	// apply integral feedback
			gy += integralFBy;
			gz += integralFBz;
		}
		else {
			integralFBx = 0.0f;	// prevent integral windup
			integralFBy = 0.0f;
			integralFBz = 0.0f;
		}

		// Apply proportional feedback
		gx += twoKp * halfex;
		gy += twoKp * halfey;
		gz += twoKp * halfez;
	}
	
	// Integrate rate of change of quaternion
	gx *= (0.5f * dt);		// pre-multiply common factors
	gy *= (0.5f * dt);
	gz *= (0.5f * dt);
	q0 += (-q1 * gx - q2 * gy - q3 * gz);
	q1 += (q0 * gx + q2 * gz - q3 * gy);
	q2 += (q0 * gy - q1 * gz + q3 * gx);
	q3 += (q0 * gz + q1 * gy - q2 * gx); 
	
	// Normalise quaternion
	recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
	q0 *= recipNorm;
	q1 *= recipNorm;
	q2 *= recipNorm;
	q3 *= recipNorm;
}

void MahonyAHRSupdate(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 q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;  
	float hx, hy, bx, bz;
	float halfvx, halfvy, halfvz, halfwx, halfwy, halfwz;
	float halfex, halfey, halfez;

	// Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
	if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
		MahonyAHRSupdateIMU(gx, gy, gz, ax, ay, az, twoKp, twoKi, dt);
		return;
	}

	// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
	if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

		// Normalise accelerometer measurement
		recipNorm = invSqrt(ax * ax + ay * ay + az * az);
		ax *= recipNorm;
		ay *= recipNorm;
		az *= recipNorm;     

		// Normalise magnetometer measurement
		recipNorm = invSqrt(mx * mx + my * my + mz * mz);
		mx *= recipNorm;
		my *= recipNorm;
		mz *= 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;   

        // 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));
        bx = sqrt(hx * hx + hy * hy);
        bz = 2.0f * (mx * (q1q3 - q0q2) + my * (q2q3 + q0q1) + mz * (0.5f - q1q1 - q2q2));

		// Estimated direction of gravity and magnetic field
		halfvx = q1q3 - q0q2;
		halfvy = q0q1 + q2q3;
		halfvz = q0q0 - 0.5f + q3q3;
        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 = (ay * halfvz - az * halfvy) + (my * halfwz - mz * halfwy);
		halfey = (az * halfvx - ax * halfvz) + (mz * halfwx - mx * halfwz);
		halfez = (ax * halfvy - ay * halfvx) + (mx * halfwy - my * halfwx);

		// Compute and apply integral feedback if enabled
		if(twoKi > 0.0f) {
			integralFBx += twoKi * halfex * dt;	// integral error scaled by Ki
			integralFBy += twoKi * halfey * dt;
			integralFBz += twoKi * halfez * dt;
			gx += integralFBx;	// apply integral feedback
			gy += integralFBy;
			gz += integralFBz;
		}
		else {
			integralFBx = 0.0f;	// prevent integral windup
			integralFBy = 0.0f;
			integralFBz = 0.0f;
		}

		// Apply proportional feedback
		gx += twoKp * halfex;
		gy += twoKp * halfey;
		gz += twoKp * halfez;
	}
	
	// Integrate rate of change of quaternion
	gx *= (0.5f * dt);		// pre-multiply common factors
	gy *= (0.5f * dt);
	gz *= (0.5f * dt);
	q0 += (-q1 * gx - q2 * gy - q3 * gz);
	q1 += (q0 * gx + q2 * gz - q3 * gy);
	q2 += (q0 * gy - q1 * gz + q3 * gx);
	q3 += (q0 * gz + q1 * gy - q2 * gx); 
	
	// Normalise quaternion
	recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
	q0 *= recipNorm;
	q1 *= recipNorm;
	q2 *= recipNorm;
	q3 *= recipNorm;
}

/*
 * [Rot_matrix,x_aposteriori,P_aposteriori] = attitudeKalmanfilter(dt,z_k,x_aposteriori_k,P_aposteriori_k,knownConst)
 */

/*
 * EKF Attitude Estimator main function.
 *
 * Estimates the attitude recursively once started.
 *
 * @param argc number of commandline arguments (plus command name)
 * @param argv strings containing the arguments
 */
int attitude_estimator_so3_comp_thread_main(int argc, char *argv[])
{

const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds

	float dt = 0.005f;
	
	/* output euler angles */
	float euler[3] = {0.0f, 0.0f, 0.0f};

	float Rot_matrix[9] = {1.f,  0,  0,
			      0,  1.f,  0,
			      0,  0,  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};

	// print text
	printf("Nonlinear SO3 Attitude Estimator initialized..\n\n");
	fflush(stdout);

	int overloadcounter = 19;

	/* store start time to guard against too slow update rates */
	uint64_t last_run = hrt_absolute_time();

	struct sensor_combined_s raw;
	memset(&raw, 0, sizeof(raw));
	struct vehicle_attitude_s att;
	memset(&att, 0, sizeof(att));
	struct vehicle_status_s state;
	memset(&state, 0, sizeof(state));

	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 200Hz */
	orb_set_interval(sub_raw, 4);

	/* subscribe to param changes */
	int sub_params = orb_subscribe(ORB_ID(parameter_update));

	/* subscribe to system state*/
	int sub_state = orb_subscribe(ORB_ID(vehicle_status));

	/* advertise attitude */
	orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);

	int loopcounter = 0;
	int printcounter = 0;

	thread_running = true;

	/* advertise debug value */
	// struct debug_key_value_s dbg = { .key = "", .value = 0.0f };
	// orb_advert_t pub_dbg = -1;

	float sensor_update_hz[3] = {0.0f, 0.0f, 0.0f};
	// XXX write this out to perf regs

	/* keep track of sensor updates */
	uint32_t sensor_last_count[3] = {0, 0, 0};
	uint64_t sensor_last_timestamp[3] = {0, 0, 0};

	struct attitude_estimator_so3_comp_params so3_comp_params;
	struct attitude_estimator_so3_comp_param_handles so3_comp_param_handles;

	/* initialize parameter handles */
	parameters_init(&so3_comp_param_handles);

	uint64_t start_time = hrt_absolute_time();
	bool 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_comp");

	/* 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_status), sub_state, &state);

			if (!state.flag_hil_enabled) {
				fprintf(stderr,
					"[att so3_comp] WARNING: Not getting sensors - sensor app running?\n");
			}

		} 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 > 3000000LL) {
						initialized = true;
						gyro_offsets[0] /= offset_count;
						gyro_offsets[1] /= offset_count;
						gyro_offsets[2] /= offset_count;
					}

				} else {

					perf_begin(so3_comp_loop_perf);

					/* Calculate data time difference in seconds */
					dt = (raw.timestamp - last_measurement) / 1000000.0f;
					last_measurement = raw.timestamp;
					uint8_t update_vect[3] = {0, 0, 0};

					/* Fill in gyro measurements */
					if (sensor_last_count[0] != raw.gyro_counter) {
						update_vect[0] = 1;
						sensor_last_count[0] = raw.gyro_counter;
						sensor_update_hz[0] = 1e6f / (raw.timestamp - sensor_last_timestamp[0]);
						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_count[1] != raw.accelerometer_counter) {
						update_vect[1] = 1;
						sensor_last_count[1] = raw.accelerometer_counter;
						sensor_update_hz[1] = 1e6f / (raw.timestamp - sensor_last_timestamp[1]);
						sensor_last_timestamp[1] = raw.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_count[2] != raw.magnetometer_counter) {
						update_vect[2] = 1;
						sensor_last_count[2] = raw.magnetometer_counter;
						sensor_update_hz[2] = 1e6f / (raw.timestamp - sensor_last_timestamp[2]);
						sensor_last_timestamp[2] = raw.timestamp;
					}

					mag[0] = raw.magnetometer_ga[0];
					mag[1] = raw.magnetometer_ga[1];
					mag[2] = raw.magnetometer_ga[2];

					uint64_t now = hrt_absolute_time();
					unsigned int time_elapsed = now - last_run;
					last_run = now;

					if (time_elapsed > loop_interval_alarm) {
						//TODO: add warning, cpu overload here
						// if (overloadcounter == 20) {
						// 	printf("CPU OVERLOAD DETECTED IN ATTITUDE ESTIMATOR EKF (%lu > %lu)\n", time_elapsed, loop_interval_alarm);
						// 	overloadcounter = 0;
						// }

						overloadcounter++;
					}

					static bool const_initialized = false;

					/* initialize with good values once we have a reasonable dt estimate */
					if (!const_initialized && dt < 0.05f && dt > 0.005f) {
						dt = 0.005f;
						parameters_update(&so3_comp_param_handles, &so3_comp_params);
						const_initialized = true;
					}

					/* do not execute the filter if not initialized */
					if (!const_initialized) {
						continue;
					}

					uint64_t timing_start = hrt_absolute_time();

					MahonyAHRSupdate(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);

					float aSq = q0*q0;
					float bSq = q1*q1;
					float cSq = q2*q2;
					float dSq = q3*q3;
					float a = q0;
					float b = q1;
					float c = q2;
					float d = q3;

					Rot_matrix[0] = aSq + bSq - cSq - dSq;	// 11
        				Rot_matrix[1] = 2.0 * (b * c - a * d);	// 12
        				Rot_matrix[2] = 2.0 * (a * c + b * d);	// 13
        				Rot_matrix[3] = 2.0 * (b * c + a * d);	// 21
        				Rot_matrix[4] = aSq - bSq + cSq - dSq;	// 22
        				Rot_matrix[5] = 2.0 * (c * d - a * b);	// 23
        				Rot_matrix[6] = 2.0 * (b * d - a * c);	// 31
        				Rot_matrix[7] = 2.0 * (a * b + c * d);	// 32
        				Rot_matrix[8] = aSq - bSq - cSq + dSq;	// 33

					/* FIXME : Work around this later...
					float theta = asinf(-Rot_matrix[6]);	// -r_{31}
					euler[1] = theta;			// pitch angle

					if(fabsf(theta - M_PI_2_F) < 1.0e-3f){
						euler[0] = 0.0f;
						euler[2] = atan2f(Rot_matrix[5] - Rot_matrix[1], Rot_matrix[2] + Rot_matrix[4] - euler[0]);
					} else if (fabsf(theta + M_PI_2_F) < 1.0e-3f) {
						euler[0] = 0.0f;
						euler[2] = atan2f(Rot_matrix[5] - Rot_matrix[1], Rot_matrix[2] + Rot_matrix[4] - euler[0]);
					} else {
						euler[0] = atan2f(Rot_matrix[7], Rot_matrix[8]);
						euler[2] = atan2f(Rot_matrix[3], Rot_matrix[0]);
					}
					*/

					float q1q1 = q1*q1;
					float q2q2 = q2*q2;
					float q3q3 = q3*q3;

					euler[0] = atan2f(2*(q0*q1 + q2*q3),1-2*(q1q1+q2q2));	// roll
					euler[1] = asinf(2*(q0*q2 - q3*q1)); // pitch
					euler[2] = atan2f(2*(q0*q3 + q1*q2),1-2*(q2q2 + q3q3)); // yaw
					

					/* swap values for next iteration, check for fatal inputs */
					if (isfinite(euler[0]) && isfinite(euler[1]) && isfinite(euler[2])) {
						/* Do something */
					} else {
						/* due to inputs or numerical failure the output is invalid, skip it */
						continue;
					}

					if (last_data > 0 && raw.timestamp - last_data > 12000) printf("[attitude estimator so3_comp] sensor data missed! (%llu)\n", raw.timestamp - last_data);

					last_data = raw.timestamp;

					/* send out */
					att.timestamp = raw.timestamp;

					// XXX Apply the same transformation to the rotation matrix
					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;

					/* FIXME : This can be a problem for rate controller. Rate in body or inertial? */
					att.rollspeed = q1;
					att.pitchspeed = q2;
					att.yawspeed = q3;

					/*
					att.rollacc = x_aposteriori[3];
					att.pitchacc = x_aposteriori[4];
					att.yawacc = x_aposteriori[5];
					*/

					//att.yawspeed =z_k[2] ;
					/* copy offsets */
					//memcpy(&att.rate_offsets, &(x_aposteriori[3]), sizeof(att.rate_offsets));

					/* copy rotation matrix */
					memcpy(&att.R, Rot_matrix, sizeof(Rot_matrix));
					att.R_valid = true;

					if (isfinite(att.roll) && isfinite(att.pitch) && isfinite(att.yaw)) {
						// Broadcast
						orb_publish(ORB_ID(vehicle_attitude), pub_att, &att);

					} else {
						warnx("NaN in roll/pitch/yaw estimate!");
					}

					perf_end(so3_comp_loop_perf);
				}
			}
		}

		loopcounter++;
	}

	thread_running = false;

	return 0;
}